Note: Descriptions are shown in the official language in which they were submitted.
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Rotor sliding-vane machine
The invention refers to mechanical engineering and can be used as a high
pressure rotor sliding-vane machine with surgeless delivery that can work both
in
the mode of a pump and hydromotor of higher efficiency and reliability.
Background of the Invention
To achieve a surgeless delivery and high efficiency a sliding-vane pump
should have a constant cross-sectional area of the working chamber in the
transfer
area, low losses for leakages and friction, and no cavitation. The mentioned
characteristics should be kept for all the operational range of the
displacement
alteration, pumping pressure and rotor rotational speed, and should little
depend on
the working fluid contamination and wear of the pump elements.
Allocation of the working chamber at the face of the rotor as, for example, in
the pump US570584, provides for the desired constant cross-sectional area of
the
working chamber, combined well with pump displacement adjustment in
US2581160, RU2123602 and US6547546.
Allocation of the working chamber in the annular groove at the face of the
rotor of pumps US1096804, US3348494, US894391 and US2341710 provides for
rotor radial unloading and rigid fixing of the vanes in the working chamber.
The main
sealings between reciprocally rotating parts in such a pump are transposed to
the
face surfaces of that part of the rotor where the annular groove is made and
hereinafter referred to as the working part of the rotor, and to the
corresponding face
surfaces of the cover plate of the housing abutting to the mentioned annular
groove
and hereinafter referred to as the working cover plate of the housing. The
mentioned
sealing face surfaces of the rotor and of the housing can be made flat.
Therefore,
technological, thermal and other clearances between flat sealing surfaces can
be
easily taken up by forward oncoming movement of one sealing surface towards
the
other due to the pressing of the working part of the rotor to the working
cover plate
of the housing.
To provide the mentioned sealing it is required to overcome great pressure
forces of the working fluid contained in the working chamber between the face
of the
rotor and the working cover plate of the housing in pumping and transfer areas
tending to deform the working part of the rotor and the working cover plate of
the
housing and to force them out from each other.
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Application of mechanical means of pressing without hydrostatical balancing
in the pumps intended for generating high pressure in the pressure line is not
efficient because of huge friction losses.
Patent EP0269474 describes a hydrostatic component (without specifying the
ways of its installation into a pump) characterized by lower influence of
axial rotor
deformations on the quality of the sealings and by using the working fluid
pressure
for reciprocal pressing of the sealing surfaces of the rotor and housing. The
rotor of
hydrostatical component consists of two parts the authors call "vanes' holder"
and
"supporting flange". On the back face of the vanes' holder, opposite to the
face with
the annular groove, in the force chambers connected to the working chamber
there
are mounted piston-like elements sliding in axial direction and abutting the
supporting flange. Thereby, the clearances between the housing the authors
call
"guideway carrier" and vanes' holder are taken up by axial movement of the
mentioned piston-like elements out of force chambers of the vanes' holder.
Working
fluid pressure forces exerted against the vanes' holder from the side of the
working
chamber are transmitted via mentioned force chambers and piston-like elements
to
the mentioned supporting flange. But the described hydrostatical component
does
not provide for any means of hydrostatical balancing from the opposite side of
the
supporting flange. The authors point out that according to the essence of the
invention the mentioned fluid pressure forces are compensated by flexible
deformation of the mentioned flange making the vanes' holder free from axial
deformations but the rotor as a whole remains hydraulically imbalanced.
According to the essence of the described by the authors of EP0269474
invention providing for unloading of the sealing pair of friction of the
vanes' holder
with the guideway carrier and transference of the forces to the static contact
of the
piston-like element with the deformable supporting flange, the mentioned
static
contact seals the force chamber and the vane chamber connected to it. When the
vane axially moves out of the rotor the fluid goes to the vane chamber through
the
channels in the vane. Increase of rotor rotational speed and axial speed of
the
moving forward vane results in increasing of the pressure drop in the
mentioned
vane channels. If the pump is operated in a self-suction mode, i.e. inlet
pressure is
equal to the atmospheric pressure, at the certain speed of the rotor rotation
hereinafter called the maximum speed of self-suction there appears cavitation
in the
vane chambers. Besides the increase of noise and pulsations the cavitation
leads to
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significant losses of useful power and efficiency of the pump. Therefore
cavitation
effects are considered here in one line with the losses on friction at the
face seals of
the rotor and of the vanes as the factors of dissipative losses decreasing the
efficiency of the pump. High tendency to cavitation and therefore low value of
the
maximum speed of self-suction is a significant disadvantage of the said
hydrostatical component.
Patent EP0265333 describes an embodiment of hydrostatical differential gear
with hydrostatical rotatory thrust block mounted between the back face of the
vanes'
holder and supporting flange rotating at different speeds. The mentioned
hydrostatical rotatory thrust block is a simple thin ring rigidly fixed to the
vanes'
holder at rotation and provided with chambers located opposite the supporting
flange. Each of the mentioned chambers is hydraulically connected via the
calibrated orifice to the opposite force chamber on the basis of hydrostatical
bearing
principle the authors call "oil thrust block". Due to that pressure forces are
transmitted to the supporting flange, and its deformation influences the
leakages
less than the similar deformation of the vanes' holder. The authors point out
that
deformations of the mentioned rotatory thrust block replicates deformations of
the
supporting flange. It means that pressure forces of the fluid acting on the
rotatory
thrust block from the side of the vanes' holder exceed the sum of pressure
forces of
the fluid from the side of the flange and elastic forces of the rotatory
thrust block and
cause an increase of deformation of the rotatory thrust block as long as
deformation
of the rotatory thrust block is sufficient for abutment to the supporting
flange. In fact,
principle of operation of the oil thrust block as a hydrostatical bearing
assumes a
dependence of the pressure in the rotatory thrust block chambers on
correlation of
the pressure drop on the calibrated orifice and pressure drop in the
clearances
between the supporting flange and rotatory thrust block. Therefore, as long as
the
mentioned clearances are large the pressure in the rotatory thrust block
chambers is
significantly lower than that in the force chambers, and due to this
difference in the
pressure forces the rotatory thrust block shifts closer to the supporting
flange. With
the decrease of the clearances the pressure in the rotatory thrust block
chamber
increases and becomes equal to the pressure in the force chamber which the
rotatory thrust block chamber is connected to via a calibrated orifice at a
complete
absence of leakages from the oil thrust blocks only i.e. when the rotatory
thrust
block entirely abuts to the supporting flange. To achieve the mentioned
abutment it
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is required to deform the rotatory thrust block in conformity with the flange
deformation. For that it is required to provide significant hydrostatical
imbalance of
the rotatory thrust block.
The mentioned elastic deformation of the rotatory thrust block required for
it's
tight abutment to the supporting flange causes increasing of friction losses.
When
the flange is deformed by pressure forces of the fluid and the thrust block is
abutted
to the flange at first a partial reciprocal contact of the deformed flange and
non-
deformed thrust block appears followed by thrust block deformation. In this
case
elastic forces of the thrust block being overcome for its deformation cause
proportionate friction losses between the rotatory thrust block and the
supporting
flange in the spots of partial contact. The mentioned thrust block is forced
out from
the flange by pressure forces of the fluid continuously distributed in
insulating
clearances, and it is pressed to the flange from the side of the force
chambers by
pressure forces distributed discretely, i.e. dropping to zero in the intervals
between
the force chambers. To provide good insulation when such method of pressing
from
the side of the force chambers is used the rotatory thrust block should be
rigid
enough. Therefore at significant pressures the said elastic forces of the
deformed
thrust block are great and the corresponding friction losses are significant.
To provide small leakages at zero or small clearances of micrometers order
hydraulic resistance of the mentioned calibrated orifices should be comparable
to
the resistance of such microscopic clearances. It does not allow using the
back face
of the rotor for intake the fluid into the vane chambers via the cavities in
hydrostatical thrust and the cavity in the housing. This, in its turn, does
not allow to
get rid of the above mentioned disadvantage of such machines, namely increased
tendency to cavitation.
Besides, such use of hydrostatical bearing with calibrated orifices for
decreasing friction forces results in lower reliability of the machines.
Firstly, when
suspended particles get into the fluid the mentioned microscopic calibrated
orifices
may become blocked up resulting in great increase of pressing forces of the
thrust
block and of the friction losses and speeding-up of wear. Secondly, in case of
local
defects on the sealing surfaces the leakages from the mentioned chambers of
the
rotatory thrust block increase and the pressure in the rotatory thrust block
chambers
drops. Tighter pressing due to the increasing difference of the pressures in
this case
does not reduce the leakages and result in balancing but rather causes greater
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losses on friction and quicker wear of the sealing surfaces. Volumetric
efficiency can
change insignificantly due to such an additional leakage from the chamber of
the oil
thrust block while the losses on friction can increase significantly.
For hydraulic balancing of the rotor of hydrostatical differential gear
described
5 in patents EP0269474 and EP0265333 the authors provide for a possibility to
use a
pair of hydrostatic components of the mentioned type in two embodiments.
The first embodiment has two guideway carriers mounted at the both sides of
one central vanes' holder. The mentioned force chambers are made in the back
part
of the guideway carrier performing the function of the sliding seal fastened
to the
housing. In this case there is formed one whole rotor with two working
chambers in
two annular grooves on the opposite faces of the rotor similar to that
described in
details in the patent US3348494.
The second embodiment has two vanes' holders mounted at the both sides
of one central guideway carrier. Vanes' holder via the force chambers bears
against
the supporting flanges that rigidly joint each other by means of a hollow
cylindrical
body forming a uniform rigid element the authors of patent EP0265333 call a
"sealed crankcase".
In both embodiments of double machine the unit formed by two guideway
carriers hereinafter shall be called stator unit or housing as the location of
suction
and pumping ports relative to it is not changed during the rotor rotation. The
first of
the described embodiments of double symmetrical machine hereinafter shall be
called a machine with internal rotor or with force closure to the housing,
while the
second embodiment shall be called a machine with internal stator or with force
closure to the rotor.
In both mentioned embodiments pressure forces of the working fluid exerted
between the rotor and housing in pumping area in one working chamber are
balanced in the second working chamber by reflection symmetric forces provided
that both working chambers are made reflection symmetric relative to the plane
perpendicular to the axis of rotor rotation.
In transfer areas axial balancing of the fluid pressure forces acting upon the
rotor does not depend on working chambers symmetry only and requires special
consideration.
In forward transfer zone at rotor rotation there arise and move closed
transferred volumes separated from suction and pumping areas by sliding
insulating
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contact of vanes with a forward transfer limiter, of vanes with vane chambers,
of
insulating surfaces of the rotor with the corresponding surfaces of the
housing and
by other clearances between the rotor, the vanes and the housing. Local
pressure in
each of the transferred volumes at other things being defined depends on the
difference of the leakages entering this transferred volume and leaving it,
depending
in their turn on the character of abutment of the surfaces of all sliding
contacts
insulating the mentioned transferred volume for different rotation angles
during its
rotation. The character of abutment of the surfaces of the sliding insulating
contact
here and hereinafter means forms and hydraulic resistance of the clearances
between such surfaces as functions of two parameters: rotation angle of the
rotor
and angular coordinate of the contact point relative to the chosen point of
the
housing. Individual character of abutment of each pair of surfaces in each
machine
is caused by technological inaccuracy during manufacturing and local defects
appearing on the mentioned surfaces as a result of wear and resulting in
spread of
insulating clearances resistance in different areas of the housing and for
different
rotation angles of the rotor. The spread of resistance of clearances can lead
to
significant spread of local pressures arising in different transferred
volumes. Similar
statements are also true for backward transfer area.
The double symmetric machine described above with internal stator has no
means of local pressures balancing in transfer areas, and transferred volumes
in
transfer areas of both symmetric working chambers are not connected to each
other. Double symmetric machine with internal rotor US3348494 has channels in
the
rotor connecting symmetric vane chambers. But symmetric cavities formed in
both
annular grooves in transfer areas between the vanes are not connected to each
other. Therefore, due to individual character of abutment of the surfaces of
insulating contacts each working chamber has different local pressures in
transfer
areas and rotor balancing is not achieved. The mentioned variable difference
of the
pressure forces acting upon the rotor in two symmetric chambers results in
proportional losses on friction in face seals. Arising local defects on
sealing surfaces
of the vanes, rotor or housing as a result of wear, for example, leads to
greater
spread of hydraulic resistance influencing local pressures in the transferred
volumes. Even in case of minor change in total leakages insignificant for
volumetric
efficiency it results in greater amplitude of the mentioned variable
difference of
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pressure forces, greater friction from the side of the smaller local pressure,
i.e. from
the side of larger wear, and speeding up of the further wear.
In the pump under patent US3348494 axial movement of the vanes in the
rotor is provided by a special vanes drive mechanism rather than by springs.
It
consists of a cam slot mounted on the housing along which the side lobes of
the
vanes going through special driving windows in the rotor slide. One skilled in
the art
can find that such vanes drive mechanism should be hydraulically insulated
from the
working chambers.
Such embodiment of the vanes drive mechanism outside the working
chamber reduces the losses on vanes friction against the surfaces of the
housing
but increases dependence of local pressures on the character of abutment of
the
surfaces of sliding insulating contact of the vanes with the walls of vane
chambers
providing hydraulic insulation of the vanes drive mechanism. Change of the
mentioned character of abutment due to wear results in the increase of
leakages
between the cavities of the working chamber and the cavity where the mentioned
drive mechanism is installed that leads to the spread of local pressures.
In both embodiments of double symmetric machines the vane moving out of
the vane chamber in axial direction is substituted by the fluid coming through
the
channels in the vane itself. Therefore cavitation losses remain a significant
disadvantage of such design.
Embodiment of the pump providing for hydraulic means of rotor balancing
and being not a subject to cavitation in vane chambers is described in patent
RU2215903. It describes reversible rotor machine containing two annular
grooves
forming working chambers at both faces of the rotor. Through openings for the
vanes pierce both annular grooves. Each cover plate of the housing has axially
movable forward transfer limiter the authors call "adjusting element" and
backward
transfer limiter the authors call "partition". The feature of the reversible
machine is
mutual antisymmetry of the two mentioned working chambers, and namely, that
-. there is an adjusting element of the second working chamber mounted
opposite the
partition of the first working chamber, and a partition of the second working
chamber
mounted opposite the adjusting element of the first working chamber. "Working
cavities" here understood by the authors as suction and pumping cavities of
both
chambers located in axial direction opposite each other are connected to each
other
by channels. Thus, the suction cavity of the first working chamber is
connected to
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the pumping cavity of the second working chamber located opposite to it, and
the
pumping cavity of the first working chamber is correspondingly connected to
the
suction cavity of the second working chamber.
When the vane is moving out of the rotor into the suction cavity of the
working chamber the fluid from the opposite pumping cavity of the other
working
chamber fills up the vacated volume in the vane chamber through the vane
chamber
of big cross-sectional area. So tendency for cavitation in the vane chambers
is not
characteristic for such a design.
When such machine is in operation there is high pressure set in one of the
connected pairs of working cavities and low pressure in the second pair
correspondingly. A possibility of hydrostatical rotor balancing in the zones
of suction
and pumping cavities location in such machine is evident.
In transfer areas due to antisymmetry of the working chambers there are
different means of insulation and different configuration of the transferred
volumes
for opposite rotor faces. Between the rotor and the adjusting element there
are
formed confined in the annular groove transferred volumes insulated by the
faces of
the vanes sliding along the adjusting element. Between the rotor and partition
located opposite the mentioned adjusting element there are formed confined in
the
vane chambers transferred volumes insulated by the sections of the bottom of
the
annular groove sliding along the mentioned partition. Distribution of the
transferred
volumes pressures and pressures in the clearances of the mentioned sliding
insulating contacts depend on form and size of the mentioned clearances, i.e.
on
character of abutment of surfaces of the mentioned sliding insulating contacts
of the
sections of the annular groove bottom with a partition and of vanes with an
adjusting
element. Non-identity of pressure distribution at the opposite faces of the
rotor
generates variable differential forces acting upon the rotor in each transfer
area
even if the mentioned contacting surface is ideally flat.
Appearance, for example, as a result of wear, of local deflections from flat
form, scratches and other local defects on the sealing surfaces of the
adjusting
elements, partitions, bottom of the annular groove, and vanes faces changes
the
character of abutment of the surfaces of the mentioned sliding insulating
contacts
thus changing the mentioned distribution of pressures and correlations of
local
pressures. That in its turn even in case of insignificant change of total
leakages
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leads to significant increase of the amplitude of the mentioned variable
differential
pressures, increase of friction and quicker wear.
Provision of face sealing between the rotor and cover plates of the housing
for both faces of the rotor by means of precise manufacturing only as in
US3348494, for example, is not reasonable, as change of clearances resulting
from
thermal expansion, deformations and wear as a rule exceed permissible
clearances
in the seals operated at high pressures. So the structure of a rotor machine
shall
also include sealing elements movable in axial direction, for example, such as
a
guideway carrier with force chambers at the side opposite the guideway
described
in EP0269474. Their imbalance also leads to the corresponding losses on
friction.
Such movable sealing is described in more details below.
The means reducing the influence of the character of abutment of the
surfaces of sliding insulating contacts in the working chamber on rotor
balancing, a
solution for overcoming the described tendency of such pumps to cavitation in
vane
chambers, and movable in axial direction sealing elements described in RU
2175731 taken by us for the closest analogue.
The mentioned patent describes a pump with a housing including working
and supporting cover plates called "housing cover plates" in the patent. The
face of
the rotor located opposite the working cover plate of the housing has a
cylindrical
annular groove going through vane chambers called in the patent "openings in
the
rotor" with the vanes called in the patent "displacers". The surfaces of the
rotor's
face that has a cylindrical annular groove located at the both sides from this
groove
contact with a possibility of sliding along the faces of the sealing elements
located
opposite them and mounted in the slots on the working cover plate of the
housing.
The pump includes a backward transfer limiter, the patent calls a "partition"
separating suction cavity from pumping cavity. Suction cavity is connected to
inlet
port the patent calls "inlet opening", while the pumping cavity is connected
to outlet
port the patent calls "outlet opening". The surfaces of the backward transfer
limiter
are in sliding contact with the rotor means of backward transfer insulation
the patent
calls "internal surfaces of cylindrical annular groove". Backward transfer
limiter is
fastened to the working cover plate of the housing and can form a single
integral
unit with it, but it is provided that in some embodiments of the pump backward
transfer limiter can be mounted with a possibility to move in axial direction
and
interact with the means of its pressing to the rotor. The pump contains a
vanes drive
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mechanism the patent calls "a mechanism setting axial arrangement of the
displacers relative each other". Forward transfer limiter is formed by part of
the
internal surface of the working cover plate. For an adjustable embodiment of
the
machine the patent calls forward transfer limiter "movable in axial direction
5 insulating element". The second face of the rotor contacts the supporting
cover plate
of the housing. The supporting cover plate of the housing of the pump provides
for a
possibility to mount a supporting-distributing member called in the invention
"supporting-distributing disc". Supporting-distributing member can be mounted
with
a possibility to move along rotor's axis.
10 The mentioned supporting-distributing member contains supporting cavities
also performing distributing functions and called in the patent "supporting-
distributing cavities". Supporting-distributing cavities are located opposite
suction
and pumping cavities of the working chamber and the means of their insulation
(insulating partitions) - opposite transfer areas providing insulation of
these
supporting cavities by means of the sliding contact with the adjacent back
face
surface of the rotor. Each supporting-distributing cavity is connected via
channels
made either in the housing or in the rotor including the vanes to the opposite
suction
or pumping area correspondingly. The dimensions and forms of the supporting-
distributing cavities are similar to those of pumping and suction cavities in
the
working chamber correspondingly. Vane chambers in the rotor are made as
through
channels connecting in suction and pumping areas to the mentioned supporting-
distributing cavities.
The mentioned through channels in the vanes or in the rotor simultaneously
connected to the suction cavity of the working chamber in this case are
parallel-
connected to each other and to the channel in the housing via the mentioned
supporting-distributing cavity. It provides for significant decrease of the
pump's
tendency to cavitation and for significant increase of the maximal self-
suction speed.
Introduction of supporting-distributing member also contributes to a certain
hydraulic balancing of the rotor. A possibility of balancing in pumping and
suction
areas is evident.
In transfer areas the similarity of distribution of pressures at the both
faces of
the rotor caused by the presence of the mentioned through channels in the
rotor or
in the vanes makes it possible to reduce the influence of the spread of
insulating
clearances in the working chamber and connected local pressures on the
difference
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of counter pressure forces acting upon both faces of the rotor. But complete
balancing of the rotor is not achieved due to different configuration of the
rotor
faces. Incomplete balancing of the rotor results in variable difference of
pressure
forces acting upon opposite faces of the rotor and causing proportional losses
on
friction in face seals.
Pressure distribution on the back side of the rotor in transfer areas is
determined by the character of abutment of the surfaces of sliding insulating
contact
between the insulating dams of the supporting-distributing member and the
rotor.
Therefore, change of the mentioned character of abutment due to appearance of
any deflections from the flat form or scratches on the sealing surfaces
resulting, for
example, from wear leads to significant disturbance of the mentioned
similarity of
pressure distribution. This in its turn even in case of insignificant change
of total
leakages leads to significant increase of the amplitude of the mentioned
variable
difference of pressure forces, greater friction and quicker wear.
Let us consider other components of loss on friction in face seals.
The internal surface of the supporting cover plate of the housing has a slot
with at least one sealing element mounted in it with a possibility to move
along the
axis of the rotor rotation. The authors point out that supporting-distributing
member
the patent calls supporting-distributing disc can be used as such an element.
Two
sealing elements are mounted in the slots on the internal surface of the
working
cover plate of the housing with a possibility to move along the axis of the
rotor
rotation.
The mentioned sealing elements are made as hollow cylinders located in the
annular slots on the internal surfaces of cover plates of the housing with a
possibility
to move along the axis of the rotor rotation. To provide the required pressing
of the
movable sealing elements to the surface of the rotor the mentioned elements
are
supported by special force chambers made inside the housing where an increased
pressure is formed. In the described machine the role of such force chambers
is
performed by the mentioned annular slots. To create increased pressure in the
mentioned annular force chambers the mentioned hollow cylinders have through
channels connecting the annular force chamber to the area of leakages in the
clearance of face sealing. The value of the increased pressure in the annular
force
chamber is determined by the form, dimensions and location of the mentioned
channels.
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The mentioned movable sealing element mounted on the housing in one
cylindrical slot with the same pressure in the whole volume is subject to
significant
over pressing to the rotor in suction area and partially in transfer areas
that causes
excessive looses on friction.
The patent EP0269474 points out a possibility to make several force
chambers insulated from each other in the housing. Different pressures are
created
in these chambers, therefore movable sealing element represented by a guideway
carrier supported by these chambers can be well balanced hydrostatically in
the
pumping and suction areas. And because of two reasons in the forward and
backward transfer zones the movable sealing element is acted upon from the
side of
the rotor by variable forces. Firstly, the area of the transfer zones at the
edges of
transfer zones connected to pumping or suction areas cyclically change.
Secondly,
the pressure in the transferred volumes of the working fluid in the process of
their
forward or backward transfer between the suction and pumping zones
continuously
changes and their position relative to the housing also continuously changes.
As a
result in the transfer zones there is formed complex, continuously changing
pressure distribution acting from the side of the rotor upon the movable
sealing
element. To create symmetrical, continuously changing pressure distribution
between movable sealing element and the housing it would be required to place
infinite quantity of insulated from each other infinitely small force chambers
each of
them connected to the corresponding point in transfer zone and isolated from
the
adjacent force chamber. As practically realizable number of force chambers in
the
housing in transfer zone is limited to rather small numbers complete
compensation
of the variable forces acting upon movable sealing is not achieved. It leads
to
variable force of pressing of the surfaces of sliding insulating contacts of
the rotor to
the mentioned sealing elements of the housing.
Change of the character of abutment of surfaces of sliding insulating contact
of the movable sealing element to the rotor because of occurrence of local
defects
of the sealing surfaces, for example, due to wear, leads to greater spread of
hydraulic resistances determining local pressures in transferred volumes.
This, in its
turn, even in case of small change of total leakages leads to greater
amplitude of
the mentioned pressing force, increased friction and speeding up further wear.
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The amplitude of this variable component achieving significant values
determines the level of losses on friction inherent in the described above
pumps
with movable sealing fastened to the housing.
So all the solutions for hydrostatical balancing of the rotor and movable
sealing considered above do not provide for complete balancing of the rotor
and
movable sealing. If the character of abutment of surfaces of sliding
insulating
contacts is not ideal, for example, when there appear local defects of sealing
surfaces due to wear, there arise great forces of pressing in friction pairs
between
sealing elements of the rotor and housing. A need to provide for such great
pressing
forces determines relatively large width of the sliding insulating contact of
the
sealing shoulders of face seals and in its turn further increases the
influence of local
defects of sealing surfaces on disbalance of the pressure forces.
All the structures described above are characterized by increased dissipative
losses decreasing their efficiency. The described means of decreasing friction
by
means of hydraulic balancing of the rotor and movable sealing do not lead to
complete balance and are not resistant to the change of character of abutment
of
sealing surfaces of sliding insulating contacts due to appearance of local
defects
and contamination of the working fluid. Even the changes of leakages
insignificant
from the point of view of the influence on volumetric efficiency can cause
significant
decrease of mechanical and total efficiency.
Essence of the Invention
The objective of the present invention is to create the means of hydrostatic
balancing of the rotor and moving seal resistant to the wear of the elements
of the
machine and working fluid contamination and compatible with the means of
overcoming cavitation in vane chambers and to increase the efficiency and
reliability
of rotor machines with the vanes in the groove.
To solve the formulated task the rotor is made adaptive, i.e. comprises two
main parts: working and supporting performing the function of the moving seal.
The
working part of the rotor has vane chambers, and on its working face surface
there
is made an annular groove connected to the vane chambers with the vanes that
are
kinematically connected to the vanes drive mechanism mounted on the housing.
The housing with inlet and outlet ports, containing supporting cover plate and
working cover plate with a forward transfer limiter and a backward transfer
limiter is
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connected to the rotor with a possibility of reciprocal rotation. Working
cover plate of
the housing is in sliding insulating contact with the working face surface of
the
working part of the rotor and forms a working chamber in the annular groove,
the
former being divided by the backward transfer limiter being in sliding
insulating
contact with the rotor means of backward transfer insulation and forward
transfer
limiter being in the sliding insulating contact with vanes into a suction
cavity of the
working chamber hydraulically connected to the inlet port and a pumping cavity
of
the working chamber hydraulically connected to the outlet port. Forward
transfer
limiter and vanes drive mechanism are made with a possibility to separate by
vanes
at least one inter-vane cavity of the working chamber from pumping and suction
cavities.
The supporting cover plate of the housing is in sliding insulating contact
with
the supporting surface of the supporting part of the rotor lying opposite the
working
surface of the working part of the rotor. The supporting part of the rotor is
kinematically connected to the working part of the rotor by an assemblage of
rotor
elements including force chambers of variable length so that to rotate
synchronously
with the working part of the rotor with a possibility to make axial travels
and tilts at
least sufficient to provide a sliding insulating contact of both said parts of
the rotor
with the corresponding cover plates of the housing. There are supporting
cavities
with insulating means made between the supporting cover plate of the housing
and
supporting part of the rotor. Each of the formed inter-vane cavities, as well
as
pumping cavity and suction cavity are hydraulically connected to at least one
force
chamber of variable length and to at least one supporting cavity via the means
of
local pressures balancing. Forms, dimensions and location of the supporting
cavities
and means of insulation are chosen so that the working fluid pressure forces
repelling the working part of the rotor from the working cover plate of the
housing
are substantially equal and directed opposite to the pressure forces of the
working
fluid repelling the supporting part of the rotor from the supporting cover
plate of the
housing. Force chambers of the variable length are made so that at any angle
of the
rotor rotation the pressure forces of the working fluid contained in the force
chambers of variable length substantially balance the said pressure forces of
the
working fluid repelling the said parts of the rotor from the corresponding
cover plates
of the housing providing just a small pressing required for insulation.
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List of Drawings
The essence of the present invention is explained by the drawings
representing the following:
5 Fig.1a - rotor sliding-vane machine with an adaptive rotor and force closure
to
the housing - cut-out quarter of the rotor - view from the side of the working
part of
the rotor, working cover plate of the housing, vanes drive mechanism and
housing
linking element are not shown;
Fig.1 b - rotor sliding-vane machine with an adaptive rotor and force closure
to
10 the housing - cut-out quarter of the rotor - view from the side of the
supporting part
of the rotor, the supporting cover plate of the housing, vanes drive mechanism
and
housing linking element are not shown;
Fig.2a - rotor sliding-vane machine with an adaptive rotor and force closure
to
the housing with the cover plates linked by a linking element located outside
the
15 rotor (housing in the form of a hollow cylinder) - axial section with the
plane passing
through the forward and backward transfer limiters;
Fig.2b - rotor sliding-vane machine with an adaptive rotor and force closure
to
the housing with the cover plates linked by a linking element located outside
the
rotor (housing in the form of a hollow cylinder) - axial section with the
plane passing
through the input and output ports;
Fig.2c - rotor sliding-vane machine with an adaptive rotor and force closure
to
the housing with the cover plates linked by a linking element located inside
the rotor
(housing in the form of a "bobbin") - axial section with the plane passing
through the
input and output ports;
Fig.2d - rotor sliding-vane machine with an adaptive rotor, force closure to
the
rotor and supporting part of the rotor coupled with the rotor linking element
made in
a form of a "bobbin" - axial section with the plane passing through the input
and
output ports;
Fig.2e - rotor sliding-vane machine with an adaptive rotor, force closure to
the
rotor and the working part of the rotor coupled with the rotor linking element
made in
the form of a "bobbin", with two working chambers in both parts of the rotor
and two
sets of vanes - axial section with the plane passing through the forward and
backward transfer limiters;
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16
Fig.2f - rotor sliding-vane machine with an adaptive rotor, force closure to
the
rotor and a rotor linking element made in the form of a "bobbin" - axial
sections: with
the plane passing through the forward and backward transfer limiters (view 1)
and
with the plane passing through the input and output ports (view 2);
Fig.2g - rotor sliding-vane machine with an adaptive rotor, force closure to
the
rotor, pivoted character of the vanes movement and the working part of the
rotor
coupled with the rotor linking element made in the form of a "bobbin" - axial
section
with the plane passing through the forward and backward transfer limiters and
section with the plane perpendicular to the axis of the rotor rotation and
passing
through the annular groove;
Fig.2h - rotor sliding-vane machine with an adaptive rotor, force closure to
the
rotor and the working part of the rotor coupled with the rotor linking element
made in
the form of a hollow cylinder - axial section with the plane passing through
the input
and output ports;
Fig.2i - rotor sliding-vane machine with an adaptive rotor, force closure to
the
rotor without rotor linking element and with working and supporting parts of
the rotor
connected by the force chambers of variable length working to attract the
parts of
the rotor to each other - axial section with the plane passing through the
input and
output ports;
Fig.2j - rotor sliding-vane machine with an adaptive rotor and force closure
to
the housing, radial character of the vanes movement and force chambers of
variable
length connected directly to the annular groove and directly to the supporting
cavities;
Fig.3a - embodiment of the force chamber of variable length: one force cavity
and one embedded element in the form of a piston with a spherical face;
Fig.3b - embodiment of the force chamber of variable length: one force ledge
and one containing element in the form of a cylinder with spherical face and
through
channel supported by the supporting part of the rotor comprising supporting
cavity
and through channel;
Fig.3c - embodiment of the force chamber of variable length: two force
cavities and one cannular connector;
Fig.3d - embodiment of the force chamber of variable length: two force
ledges and one cannular connector;
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17
Fig.3e - embodiment of the force chamber of variable length: containing
element in the supporting part of the rotor, force ledge in the working part
of the
rotor and a connector comprising containing element and embedded element;
Fig.3f - embodiment of the force chamber of variable length working to attract
the parts of the rotor to each other;
Fig.3g - embodiment of the force chamber of variable length: one containing
element is made in the working part of the rotor, the second containing
element
comprising the supporting cavity and through channel flatly slides along the
supporting part of the rotor, a connector in the form of cylinder with
spherical face
and a through channel, is supported by the second containing element;
Fig.4a - forward transfer area - fragment of circular development of the
annular groove;
Fig.4b - backward transfer area - fragment of circular development of the
annular groove;
Fig.5a - embodiment of the means of local pressures balancing: annular
groove - channel in the working part of the rotor - vane chamber - channel in
the
force chamber - channel in the supporting part of the rotor - supporting
cavity;
Fig.5b - embodiment of the means of local pressures balancing: annular
groove - channel in the vane - vane chamber - channel in the force chamber -
channel in the supporting part of the rotor - supporting cavity;
Fig.5c - embodiment of the means of local pressures balancing: force
chamber - vane chamber - channel in the vane - annular groove - channel in the
operational unit of the housing - supporting cavity in the operational unit of
the
housing;
Fig.5d - embodiment of the means of local pressures balancing: vane
chamber - channel in the vane - annular groove - channel in the operational
unit of
the housing - supporting cavity in the supporting part of the rotor - channel
in the
supporting part of the rotor - force chamber of variable length;
Fig.5e - fragment of the means of local pressures balancing: supporting
cavities in the form of a radial slots in the housing connected to the
channels in the
form of longitudinal arc slots in the supporting part of the rotor;
Fig.5f - embodiment of the means of local pressures balancing: force
chamber of variable length - annular groove - channel in the operational unit
of the
housing - supporting cavity in the operational unit of the housing;
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18
Fig.6 - embodiment of hydro-tightening of the vanes: vane chamber
connected to both adjacent inter-vane cavities via the channels with valves;
Fig.7 - embodiment of the bottom unloading cavities and bottom sealing
ledges: bottom cavity separated by two bottom ledges from both adjacent vane
chambers and connected via the channel to the force chamber of variable length
-
fragment of circular development of the annular groove;
Fig.8a - embodiment of the supporting cavities: supporting cavities in the
rotor are connected to the channels in the rotor - fragment of circular
development
of the annular groove;
Fig.8b - embodiment of the supporting cavities: supporting cavities in the
rotor are connected to the channels in the housing - fragment of circular
development of the annular groove;
Fig.9 - rotor sliding-vane machine with an adaptive rotor and force closure to
the housing - transferred volume in the suction, forward transfer, pumping and
backward transfer areas - circular development of the annular groove;
Fig.10 - cover plates of the housing comprising anti-deformation chambers
made between the functional elements and load-bearing elements of the cover
plates;
The basic idea of the present invention provides for numerous embodiments
of a rotor sliding-vane machine suitable for use as a pump or as a hydro motor
both
reversible and with fixed direction of the rotor rotation, and also as a
pumping-motor
unit of hydromechanical transmission. In some embodiments of the invention the
housing is fixed to the rack of the aggregate and the rotor rotates relative
the
housing and the rack of the aggregate. In other embodiments of the invention
the
rotor can be fixed to the rack of the aggregate and the housing rotates
relative it. It
is also possible to have an embodiment with the rotor and the housing rotating
relative to the rack of the aggregate, for example, if the rotor machine is a
unit of a
hydromechanical transmission. Hereafter we shall consider relative rotation of
the
rotor and housing irrespective of the type of installation of the rotor
machine in the
aggregate. In any case the rotor will mean a unit having an annular groove in
the
face element and having the vanes making cyclical movements relative the rotor
at
every turn of the rotor, changing the degree of their sliding into the annular
groove.
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19
The housing is a unit relative to which the location of inlet and outlet ports
does not
change at reciprocal rotation of the rotor and the housing.
Hereinafter the preferred embodiments of all essential elements of the rotor
machine are described. There is also a detailed description of the structure
and the
operation of the preferred embodiment of machine working as a multi-purpose
pump.
An adaptive rotor depicted in Fig.1 a, lb is divided into two parts, working
part
1 with face annular groove 2 made in it's working face forming the working
chamber
and being in sliding contact with insulating surfaces of working cover plate 3
of the
housing Fig.2a, 2b, and supporting part 4 with the supporting face being in
sliding
contact with the insulating surfaces of supporting cover plate 5 of the
housing.
These two parts of the rotor are connected to each other by an assemblage of
rotor
elements so that they can rotate synchronously but having a possibility to
make
small axial movements and tilts relative each other in order to keep sliding
insulating
contact with both cover plates of the housing at rotor rotation. The mentioned
assemblage of rotor elements 'includes known from the prior art means of the
rotation synchronization made, for example, in the form of a joint of equal
angular
velocities and also includes rotor force chambers of variable length 6 Fig.3a,
3b, 3c,
3d, 3e, 3f, made so that the pressure forces acting upon working part of the
rotor 1
from the side of the working chamber in annular groove 2 and from the side of
force
chambers 6 change synchronously in transfer areas. For this purpose the number
of
such force chambers 6 shall be equal or divisible by the number of vane
chambers 7
and each force chamber of variable length 6 is hydraulically connected to
annular
groove 2 of working part of the rotor 1, so that each cavity being formed
during the
rotation of the rotor in annular groove 2 of working part of the rotor 1 in
forward
transfer area between two adjacent vanes 8 and characterized by its individual
character of local pressure changing is hydraulically connected to its force
chamber
of variable length 6 so that local pressures in the mentioned cavity and in
the force
chamber 6 connected to it are substantially equal. In the preferred embodiment
of
the invention each force chamber of variable length is connected to the
nearest
cavity in the annular groove.
Force chambers of variable length are made so that the change of their
length leads to the mentioned reciprocal movements of the working and
supporting
parts of the rotor required for insulation. According to the essence of the
invention
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pressure forces of the working fluid in the mentioned force chambers applied
to the
working and supporting parts of the rotor do not depend at given pressure on
the
change of the force chamber length.
The said force chambers of variable length can be made differently, for
5 example, using bellows or elastic side walls. The preferred embodiment of
the
invention has a force chamber of variable length formed by containing elements
and
embedded elements mounted with a possibility of reciprocal movement, with
outer
walls of the embedded elements being in sliding insulating contact with the
inner
walls of the containing elements so that they seal the force chamber at the
10 mentioned reciprocal movements of the working and supporting part of the
rotor
required for insulation.
Embedded and containing elements can be made as elements separate from
the parts of the rotor but kinematically connected to them. The preferred
embodiments of the invention provide for that the mentioned containing or
15 embedded elements are made directly on the parts of the rotor. The first
embodiment has a containing element that can be made as force cavity 14
Fig.3a,
like a cylinder, in the working or supporting part of the rotor, and if the
rotor contains
a linking element as, for example, described below for the machines with force
closure to the rotor, the mentioned force cavities can be made in the linking
element
20 of the rotor. The second embodiment has embedded element 10 Fig.3b that can
be
made as a force ledge, like a piston, on the working or supporting part of the
rotor
and on the linking element of the rotor as well.
If the amplitudes of the mentioned reciprocal movements of the working and
supporting parts of the rotor are little the force chamber can be made by one
pair of
containing and embedded element, for example, as a hydro cylinder Fig.3a, 3b.
If there are expected big amplitudes of the mentioned reciprocal movements
of the parts of the rotor, especially reciprocal tilts, the present invention
provides for
an embodiment of the force chamber of variable length as two pairs of
containing
and embedded elements, for example, when force chamber of variable length is
formed by two containing elements 11 Fig.3c mounted with a possibility of
reciprocal
movements and by one embedded element in the form of connector 12 with
external
walls being in sliding insulating contact with the internal walls of both
containing
elements.
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21
In Fig.3g one containing element is made as a cylindrical cavity in working
part of the rotor 1, and second containing element 11 with internal spherical
insulating surface and external flat insulating surface is mounted so that its
flat
surface is in sliding contact with the flat surface of supporting part of the
rotor 4.
Embedded element in the form of connector 12 has external cylindrical and
spherical insulating surfaces being in sliding insulating contact with
internal
cylindrical and spherical surfaces of the containing elements correspondingly.
In other embodiments the force chamber is formed by two embedded
elements 10 Fig.3d mounted with a possibility of reciprocal movement and by
one
containing element in the form of connector 12 with internal walls being in
sliding
insulating contact with external walls of both embedded elements, or force
chamber
is formed by first containing element 11 Fig.3e and the first embedded element
mounted with a possibility of reciprocal movement and by the second containing
element combined with the first embedded element into one connector 12 with
external walls being in sliding insulating contact with internal walls of the
first
containing element and internal walls being in sliding insulating contact with
external
walls of the second embedded element.
The mentioned sealing of the sliding contact at axial movements and tilts can
be made in accordance with the nowadays state of arts, for example, using
spherical sealing shoulders 13 Fig.3a, 3b, 3c, 3d, 3e on external surface of
the
embedded elements.
The preferred embodiment of the invention provides for force chambers of
variable length made so that reciprocal movement of the mentioned containing
and
embedded elements of the force chamber when its length is changed is directed
significantly parallel to the axis of the rotor rotation. There is provided
such an
embodiment of the mentioned force chambers that pressure forces of the working
fluid contained in the force chamber tend to increase total length between the
ends
of its elements, for example, by displacing the embedded element from the
containing element or by pushing apart the pair of the elements connected by
sliding
contact to the connector and to move the working and supporting parts of the
rotor
closer to the corresponding cover plates of the housing. For the embodiments
of the
machine with force closure to the rotor described below the invention also
provides
for such an embodiment of force chambers of variable length that pressure
forces of
the working fluid contained in the force chamber tend to decrease total length
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22
between the ends of its elements, for example, by pushing embedded element 10
into containing element 11 Fig.3f, and so moving the working and supporting
parts
of the rotor closer to each other and to the corresponding cover plates of the
housing combined into the operational unit of the housing located between the
working and supporting parts of the rotor.
If required force chambers can be made so that the mentioned reciprocal
movement of the elements forming these chambers is directed significantly
unparaliel to the axis of rotor rotation. In this case it is assumed that the
mentioned
assemblage of rotor elements providing kinematical connection of the working
and
supporting parts of the rotor includes the means of transforming the forces
direction
in order to transfer the movements of the force chamber elements to the
working
and supporting parts of the rotor. The mentioned means of transforming the
forces
direction can include leverage, cam or other elements known from the prior art
used
for similar purposes.
Fig.1 a, 1 b, 3c present force chambers 6 connected to vane chambers 7 and
including force cavities 14 in the supporting and working parts of the rotor
and
cannular connectors 12 with sealing shoulders 13 mounted with their ends in
the
mentioned force cavities so that to seal force chambers at reciprocal axial
movements and tilts of the working and supporting parts of the rotor.
According to the invention force chambers of variable length have elastic
elements, for example, springs, to provide sealing pressing of the parts of
the rotor
to the cover plates of the housing at zero or low pumping pressure.
Generally, inter-vane cavities of the working chamber formed in transfer area
in annular groove 2 can be unconnected to the cavities formed in transfer area
in
vane chambers 7 and inside vanes 8. In this case the pressure in these
cavities
shall change differently and for complete balancing it will be required to
juxtapose
each of that cavities with the corresponding force chamber of variable length
6.
Their number will be divisible by the number of vane chambers. But to provide
self-
sealing of the face surfaces of vanes 8 sliding along forward transfer limiter
15
Fig.4a it is convenient to connect the cavity located in vane chamber 7 from
the side
of the vane's face opposite the sealing face to that cavity in annular groove
2
between the mentioned vane and the adjacent vane from which the mentioned vane
displaces the fluid to the pumping cavity. In case of a hydromotor the fluid,
on the
contrary, displaces the vane. Therefore, in general case to provide
hydrostatical
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23
tightening of vane 8 to the surface of forward transfer limiter 15 the
mentioned cavity
in vane chamber 7 should be connected to that of two cavities in the annular
groove
between the said vane and the adjacent vanes that has higher pressure. In this
case
the opposite face of the vane shall be acted upon with greater force than the
sealing
face and vane 8 shall be pressed to forward transfer limiter 15 with a force
proportional to the pressure difference between the inlet and the outlet. In
order to
prevent excessive losses on friction between the surface of vane 8 and forward
transfer limiter 15, the mentioned surface of the vane shall have vane
unloading
cavity 16 hydraulically connected to the cavity in the vane chamber adjacent
to the
opposite surface of the vane and vane sealing ledge 17. Form and area of vane
unloading cavity and vane sealing ledge should be determined by means of
optimization of proportion between the leakages rate in the clearance of
sliding
insulating contact of vane's surface with the transfer limiter and amount of
friction
losses of the face of the vane on the forward transfer limiter.
One of the preferred embodiments of the invention provides for axially
movable vane 8 containing through channel 18 connecting the mentioned cavity
in
the vane chamber to vane unloading cavity 16 on the surface of the vane
sliding on
the forward transfer limiter, and vane sealing ledge 17 made so that the
mentioned
vane unloading cavity 16 is connected to the inter-vane cavity described
above.
Another embodiment of the invention provides for channels 19 Fig.5a made in
the
working part of the rotor connecting the mentioned cavities in the vane
chambers to
the corresponding inter-vane cavities in annular groove 2.
In case of such connection of the cavities the number of the insulated
transferred volumes is equal to the number of vane chambers of the working
part of
the rotor. Accordingly, the number of force chambers can be the same.
If the machine is made convertible, i.e. intended for use as a pump or as a
motor and if the machine is made reversible, i.e. capable of changing the
direction
of working fluid flow without changing the direction of the rotor rotation,
location of
the higher pressure cavities relative to the chosen vane chamber in forward
transfer
area changes when the working mode is changed. In this case to provide the
described hydro tightening of the vanes the channels of the mentioned
hydraulic
connection of vane chambers to the annular groove are provided with valve
elements 69 so that the vane chamber is connected to that cavity in the
annular
groove between the said and the adjacent vanes where the pressure is higher
Fig.6.
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In such an embodiment it is reasonable to make some force chambers of variable
length connected via the channels to the cavities in the annular groove
between the
vanes directly, and the other force chambers of variable length connected to
the
vane chambers. In case of such a connection the number of force chambers of
variable length should be reasonably chosen equal to doubled number of the
vane
chambers of the working part of the rotor. In this case vane sealing ledges 17
sliding
on forward transfer limiter 15 separate vane unloading cavities 16 from both
adjacent inter-vane cavities in annular groove 2. There is also provided such
an
embodiment of through channels in a vane that vane unloading cavities are
bound
by the walls of the mentioned channels.
The pressure in the mentioned force chambers of variable length is always
equal to the pressure in the corresponding cavities in the annular groove. To
balance pressure forces of the fluid acting upon the working part of the rotor
from
the side of the working cover plate of the housing with pressure forces of the
fluid
from the side of the force chambers, size, form and location of the force
chambers
shall be chosen on the basis of configuration of pressure forces distribution
between
the working part of the rotor and working cover plate of the housing. The
mentioned
pressure forces are formed both by the fluid located in the cavities of the
working
chamber and fluid flowing between adjacent cavities of the working chambers
with
different pressures and the fluid flowing out of the cavities of the working
chamber
through clearances of face seals.
The invention provides for two embodiments of rotor means of backward
transfer insulation.
In the first embodiment in backward transfer area as well as in forward
transfer area the insulation is provided by sliding contact of spots of the
face
surfaces of the vanes with the surface of the corresponding transfer limiter.
In this
case configuration of the cavities and corresponding seals between the working
part
of the rotor and working cover plate of the housing determining geometrical
distribution of pressure forces of the working fluid repelling the working
part of the
rotor from the working cover plate of the housing are similar in both transfer
areas
and allow for easy determining of the required characteristics of the force
chambers.
But it should be taken into consideration that in this case the location of
the nearest
inter-vane cavity with a higher pressure relative to the chosen vane chamber
shall
differ for forward transfer area and backward transfer area as described above
for
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forward transfer area of reversible or convertible machines. Therefore
embodiment
of hydraulic connection of the vane chambers with the annular groove for hydro
tightening of the vanes and embodiment of force chambers shall be similar to
that
described above for such machines.
5 In the second embodiment of design the insulation in the working chamber in
forward transfer area B Fig.4a is provided by sliding contact of vane 8 with
the
surface of forward transfer limiter 15 and the insulation in the working
chamber in
backward transfer area D Fig.4b is provided by sliding contact of a spot of
the
bottom of the annular groove in the face of the rotor with the surface of
backward
10 transfer limiter 21. In this case configuration of the cavities in the
annular groove
connected to the corresponding force chambers and of the corresponding seals
generally is not identical for forward and backward transfer areas. As a
result
pressure forces of the fluid acting upon the working part of the rotor from
the side of
the working cover plate of the housing may differ in value at the same
pressure in
15 the transferred volumes in forward and backward transfer areas. Besides,
the
centers of these forces application to the working part of the rotor are
shifted if put
on the same fragment of the rotor. The shift value of the center of the fluid
pressure
forces application to the working part of the rotor depends on the dimensions
and
location of the sealing surfaces of the vane face and the spot of the annular
groove
20 bottom relative to each other.
In order to the force chamber of constant configuration could provide
balancing of the effects on the working part of the rotor from the side of the
working
chamber in both areas there is offered a method of minimizing the change of
geometrical characteristics of the cavities in the annular groove by
minimizing the
25 areas of the sealing spot on the surface of the bottom of the groove in the
rotor and
maximum approaching of these parts to the sealing spots of the face surfaces
of the
vanes. For this purpose the surface of the annular groove bottom between the
vanes has bottom unloading cavities 22 and sealing ledges 23 Fig.4b. The
mentioned bottom sealing ledges are in sliding insulating contact with the
backward
transfer limiter and divide adjacent transferred volumes in backward transfer
area D.
For reversible or convertible machines the preferred embodiment of the
invention Fig.7 provides for such an embodiment of bottom unloading cavities
and
sealing ledges where every spot of the annular groove bottom between two
adjacent
vane chambers 7 has at least two sealing ledges 23 and one unloading cavity 22
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26
between them so that in backward transfer area the mentioned bottom unloading
cavity is separated by sliding insulating contact of two mentioned bottom
sealing
ledges with backward transfer limiter 21 from both nearest vane chambers 7. In
this
case the means of local pressures balancing include channels 24 in the working
part
of the rotor via which every bottom unloading cavity 22 is connected to its
force
chamber of variable length 6, nearest with regard to closest angular distance.
There
is also provided such an embodiment of the mentioned channels 24 where their
cross dimensions are close or even equal to the dimensions of the bottom
unloading
cavities. In the latter case the mentioned bottom unloading cavities are
bounded by
the walls of the mentioned channels.
For the machines with the fixed location of high pressure cavities relative to
the inlet and outlet port it is provided that every spot of the annular groove
bottom
between two neighboring vane chambers has one unloading cavity and one sealing
ledge adjacent to the first of the two mentioned vane chambers with a vane
separating the mentioned bottom unloading cavity in forward transfer area from
high
pressure cavity and the unloading cavity is connected to the second mentioned
vane chamber. Fig.7 presents vane sealing ledge 17 and neighboring bottom
sealing ledge 23 located as close to each other as possible, i.e. on the
adjacent
spots of the corresponding surfaces.
In case of the described embodiments of bottom unloading cavities and
sealing ledges choosing the dimensions of force chambers allows for axial
balancing of the working part of the rotor in both transfer areas. Shift of
the centers
of pressure force application to the working part of the rotor from the side
of the
working cover plate of the housing will lead to the appearance of variable
moments
of forces tending to turn the working part of the rotor around the axis
perpendicular
to the axis of the rotor rotation. Therefore the force chambers are located
with a shift
so that the moments of the forces arising in forward and backward transfer
areas
compensate each other.
To provide sealing between face surfaces of the working part of the rotor and
the corresponding surfaces of the working cover plate of the housing it is
reasonable
to choose the form and dimensions of the force chambers inside the rotor so
that to
provide a small pressing of the working part of the rotor to the sealing
elements of
the working cover plate of the housing. To provide the required pressing the
sum of
cross-sectional areas of all force chambers of variable length shall exceed
the area
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of the projection of the annular groove to the plane perpendicular to the axis
of
rotation of the working part of the rotor for a value depending on the area
and
character of abutment of the surfaces of sliding insulating contact of the
working part
of the rotor with the working cover plate of the housing.
For example, in case of flat clearances between the surfaces of the
mentioned sliding insulating contact to calculate the balance of pressure
forces it is
required to add at least 50% of the area of the mentioned sliding insulating
contact
to the mentioned area of projection of the annular groove. In case of non-flat
insulating surfaces and clearances between them the corresponding coefficient
by
which the area of the sliding insulating contact of the working part of the
rotor with
the working cover plate of the housing is multiplied while summing up with the
area
of the mentioned projection of the annular groove can be determined
empirically.
Minimum required value of the mentioned area excess is determined taking
into account the elasticity of elastic elements of force chambers of variable
length
and friction forces that have to be overcome to provide the required
reciprocal
movements of the working and the supporting parts of the rotor. The mentioned
friction forces include friction forces in sliding insulating contacts between
the
embedded and containing elements of the force chambers and rotor elements
transmitting the torque, for example, joints of equal angular velocities.
Balancing the supporting part of the rotor: supporting cavities and means of
local pressures balancing.
Supporting part 4 Fig.1 b of the rotor is exposed to the symmetrical forces
from the side of force chambers of variable axial length 6 towards the
corresponding
surface of supporting cover plate 5 of the housing. Thus, the working and
supporting
parts of the rotor move apart to abut against the corresponding sealing
surfaces of
the housing.
Each of the force chambers of variable axial length 6, including those located
opposite forward 15 or backward transfer limiter 21, is hydraulically
connected via
the means of local pressures balancing to the nearest cavity of the working
chamber
(2) of working part of the rotor 1 and the nearest supporting cavity 25
confined
between the surfaces of the supporting end of supporting part of the rotor 4
and the
surfaces of supporting cover plate of the housing 5.
The means of local pressures balancing are meant hereinafter to be a set of
channels and cavities that being intercommunicated form a manifold of
hydraulic
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28
circuits through which each of the force chambers of variable axial length is
hydraulically connected to the cavity of said location in the working chamber
and
supporting cavity of said location. Thereby, from the point of view of
hydraulic
balancing of the working and supporting parts of rotor the pressure in the
force
chamber is substantially equal to the corresponding pressure in the cavities
hydraulically connected to it at any angle of the rotor rotation and at any
leaks from
any cavity or force chamber that are admissible in terms of the volumetric
efficiency
of the hydraulic machine. Said channels and cavities can be made both in the
rotor
and in the housing. In the latter case the channels and the cavities of the
housing
are connected to the channels and cavities of the rotor during rotation of the
rotor.
For the various embodiments of the machine with force closure to the
housing described below the preferred embodiment of the invention provides for
the
means of local pressures balancing realized by the channels and cavities in
the
rotor Fig. 5b. In this case hydraulic circuit of the means of local pressures
balancing
includes channels in the working part of the rotor connecting annular groove 2
of
working part of the rotor 1 with force chambers of variable axial length 6,
for
example, channels 18 in vanes 8, and vane chambers 7, directly connected to
said
force chambers 6, includes through channels 26 in force chambers 6 and also
includes channels in supporting part of rotor 27 connecting force chambers 6
to
supporting cavities 25.
For the various embodiments of the machine with force closure to the rotor
described below the preferred embodiment of the invention provides for the
means
of local pressures balancing Fig.5c, 5d, 5e made as a combination of channels
and
cavities in the rotor with channels 27-1 and cavities 25 in the housing in
this case
connecting the annular groove of the working part of the rotor to the
supporting
cavities between supporting cover plate of the housing 5 and supporting part
of the
rotor 4.
In the preferred embodiment of the invention the mentioned supporting
cavities 25 are made in supporting part of the rotor 4. In Fig.5b, 8a, 8b
supporting
cavities of the supporting part of the rotor are connected by means of
channels 27
or 27-1 to force chambers 6 inside the rotor with channels 26 in connectors
12.
Thus, the pressure in every supporting cavity is always equal to the pressure
in the
corresponding force chambers of variable axial length and to the pressure in
the
corresponding cavity of the working chamber of the working part of the rotor
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29
independently of the sealing surfaces defects, size of clearances in the end
sealings
and corresponding leakages from the supporting cavities and between them. Said
leakages depend on the character of abutment of the surfaces of sliding
insulating
contact of the supporting cover plate of the housing to insulating means of
the
supporting cavities of the supporting part of the rotor. These insulation
means of the
supporting cavities include insulating dams 57 between the cavities; the
character of
their abutment to the supporting plate of the housing determines the leakages
between supporting cavities, and peripheral end sealings 58; the character of
their
abutment to the supporting plate of the housing determines the leakages from
the
supporting cavities to the drainage Fig.1 b.
Location, form and area of supporting cavities 25 on the outer end of the
supporting part of the rotor taking into account the area of the sliding
insulating
contact of the means of insulating supporting cavities with the supporting
cover plate
of the housing and pressure distribution in it are chosen so that the pressure
forces
acting on the supporting part of the rotor from force chamber of variable
length are
substantially balanced by the pressure from the supporting cavities leaving
just a
small pressing of the supporting part of the rotor to the corresponding
sealing
elements of the housing required for insulation. Thus, supporting cavities
actually
perform the role of unloading the supporting part of the rotor. The invention
also
provides for an embodiment with supporting cavities directly connected to the
force
chambers of variable length.
To provide the required for insulation pressing of the supporting part of the
rotor to the supporting cover plate of the housing the total cross-section
area of the
force chambers of variable length exceeds the total area of the supporting
cavities
projection on the plane perpendicular to the axis of rotation of the
supporting part of
the rotor summed up with the total area of the insulation means of supporting
cavities multiplied by the corresponding weight ratio determined by the
average for
rotor rotation angles area and character of abutment of the surfaces of
sliding
insulating contact of the supporting part of the rotor to the supporting plate
of the
housing equal, for example, to 50% in case of flat surfaces, like described
above for
the working part of the rotor. Minimum required area excess also depends on
elasticity of the elastic elements of force chambers and described above
friction
forces that have to be overcome for necessary mutual movements of working and
supporting parts of rotor.
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For the embodiments of the machine as a hydromotor or a pump operating in
a range of rotation speed and suction pressure generating no cavitation in
vane
chambers at the chosen type of vanes movement supporting cover plate can have
no cavities. A variant of cover plate of the housing with distributing
cavities to reduce
5 a possibility of cavitation is described below.
The number of the supporting cavities in the supporting part of the rotor is
equal or multiple of the number of vane chambers in the working part of the
rotor.
In preferred embodiment the number of supporting cavities equal to the
number of force chambers of variable length and to the number of vane chambers
in
10 the working part of the rotor, and the sum of the supporting cavity area
and half of
the area of the sliding insulating contact of the corresponding means of
insulation
with the supporting cover plate of the housing equal to the sum of the area of
the
opposite cavity formed in the annular groove of the working part of rotor in
backward
transfer zone and half of the area of the sliding insulating contact of the
15 corresponding means of insulation with the working plate of the housing.
In particular case supporting part of the rotor has an annular groove and
vanes located in vane chambers. The vanes closing the annular groove divide it
into
separate supporting cavities with local pressures balanced with local
pressures in
the corresponding cavities of the working chamber and force chambers of
variable
20 length by means of local pressures balancing.
In this case the surface of the supporting cover plate can include forward and
backward transfer limiters. Then there is formed a second working chamber in
the
annular groove between the supporting part of the rotor and supporting cover
plate
of the housing. The mentioned second working chamber can be made either
25 symmetrical to the first one as described in US3348494, or asymmetrically
as
described in RU2215903. In the latter case rotor machine has an opportunity of
a
reverse work, i.e. it can change the direction of the fluid flow without
changing the
direction of the input shaft rotation. The term symmetrically shall be
considered with
regard to the symmetry of the pressure forces at all the rotor positions. The
second
30 annular groove can differ in size from the first one provided the balance
of the
supporting part of the rotor described above. Means of insulation of
supporting
cavities include vanes with the surfaces sliding along the forward transfer
limiter of
the supporting cover plate of the housing and rotor means of insulation of
backward
transfer sliding along the backward transfer limiter of the supporting cover
plate of
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the housing. Similar to the described above variants of the working part of
the rotor
the vanes of the supporting part of the rotor can have vane unloading cavities
and
vane sealing ledges while rotor means of backward transfer insulation can
include
either vanes or parts of annular groove bottom of the supporting part of the
rotor
with similar bottom unloading cavities and bottom sealing ledges.
For a machine with annular grooves and vane chambers in both parts of the
rotor and with transfer limiters on the both cover plates of the housing the
definitions
"working" and "supporting" part with regard to the parts of the rotor are
conventional
and used for the unity of the terminology.
The invention also provides for an embodiment with more than one pair of the
forward and backward transfer limiters on the working cover plate of the
housing.
Each pair of the limiters forms an additional pair of suction and pumping
cavities in
the annular groove connected to the input and output ports correspondingly.
The
vanes drive mechanism in such multicycle machine is made so that every vane
performs as many relocation cycles relative to the annular groove during one
rotation of the rotor as many pairs of the limiters on the working cover plate
of the
housing are made.
Multicycle embodiment is applicable to the machines described above with
two annular grooves (in the working and supporting parts of rotor). In such
machines
the working and supporting cover plates of the housing have the same number of
backward and forward transfer limiters. The invention provides for both
symmetric
and antisymmetric location of suction and pumping cavities formed in annular
grooves of the working and supporting parts of rotor.
Thus for any character of abutment of the surfaces of the said sliding
insulating contacts independent of the leakages determined by the said
character of
the sealing surfaces abutment, variable pressure forces of the working fluid
acting
on the working and supporting parts of rotor from the corresponding cover
plates of
the housing are substantially balanced by the same variable pressure forces of
the
working fluid acting from the force chambers. Minor pressing required for end
sealing can be reasonably made very small.
Means of local pressures balancing implicate channels 27 with large flow
area and small hydraulic resistance, which makes their obstructing with
suspended
particulate matters practically impossible and eliminates the influence of
suspended
particulate matters in the working fluid on the described balance of the
pressure
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32
forces. In particular embodiment of the invention cross sectional dimensions
of
channels 27 are close to cross sectional dimensions of supporting cavities 25
or
even equal to them.
Due to the mentioned properties of the means of local pressures balancing
no matter how large is dispersion of the local pressures in different
transferred
volumes caused by local defects on the insulating surfaces resulting, for
example,
from wear, balancing of the rotor parts is not significantly disturbed.
One skilled in the art can find that removing the causes of significant
imbalance results in significant reduction of the sliding insulating contacts
area. In
the preferable embodiment of the invention the total area of projection of the
sliding
insulating contact of insulating means of supporting cavities of the
supporting part of
the rotor with the supporting cover plate to the plane perpendicular to the
rotor
rotation axis is significantly smaller than the sum of the areas of the
supporting
cavities; and total area of projection of sliding insulating contact of the
working part
of the rotor with the working cover plate of the housing to the plane
perpendicular to
the rotor rotation axis is significantly smaller than the area of projection
of the
annular groove of the working part of rotor to the same plane. So, no matter
how
distribution of pressure changes in clearances of sliding sealing contacts of
the parts
of rotor with cover plates of the housing in case of local defects the
influence of
these changes on the balance of pressure forces acting upon every part of the
rotor
becomes insignificant.
Implementation of a distribution suction cavity in the supporting cover plate
opposite the suction cavity lowers the tendency for cavitation as the
mentioned
distribution suction cavity provides hydraulic connection to the corresponding
vane
chamber with suction cavity 28 of the working chamber through other vane
chambers or through channels in the rotor or in the housing. In suction cavity
several vanes are at the same time at different stages of acceleration or
slowdown
Fig. 9. Vane chambers 7 in suction cavity are connected to the mentioned
distribution suction cavity 28-1 through force chambers 6, that in their turn
are
connected by channels 27 to supporting cavities 25 of the supporting part of
the
rotor making a through hydraulic circuit. Hydraulic resistance of channels 27
and
other components of the mentioned hydraulic circuit is low. So by means of the
distribution suction cavity, channels 18 in these vanes in this case are
connected in
parallel. The fluid flows into the vane chamber of the vane with large axial
speed not
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through the channels in that vane itself but through the channels in the vanes
with
low axial speed thus reducing pressure drop in the mentioned vane chamber. The
degree of increasing of the maximum speed of self-suction in this case depends
on
the number of the vanes that are simultaneously in the suction cavity. If the
channels are made in the rotor between the vanes rather than in vanes the
effect of
fluid redistribution flowing to vane chambers to replace protruding vanes
through
parallel channels and distributing cavity is the same. Increasing of the
maximum
self-suction speed by several times is an important advantage of the pumps
with
distributing cavity. Connection of the distributing cavity to the suction port
by means
of a channel in the housing further increases ultimate rotor rotation speed
without
cavitation. In case distributing pumping cavity is made opposite the pumping
cavity
and is connected by the channel in the housing to the pumping port hydraulic
losses
of the pump are decreased.
Another way to overcome tendency for cavitation and to increase ultimate
self-suction speed is to change the type of vanes movement. If axial movement
of
the vane is replaced by vane rotation around some axis, for example, an axis
parallel to the rotor rotation axis, this removes any need for vane channels
or
parallel channels as to inplace the turning vane the fluid flows round it in
the vane
chamber of large flow area without any significant pressure drop. To implement
such a means it is more convenient to use hydromachines with force closure to
the
rotor rather than to the housing. More detailed description of the differences
between these two types of architecture and a sample of implementing such
vanes
movement can be found below.
Force closure to the housing and anti-deformation chambers.
The above description refers to the embodiments of rotor machine with the
rotor made between the working and supporting face cover plates of the housing
and the working chamber and supporting cavities made on external face surfaces
of
the rotor. Axial pressure forces of the working fluid acting upon the rotor
and each
part of the rotor, working and supporting, balance each other and compress
each
part of the rotor. Compression deformation can be ignored for steel works.
Axial
component of stretching pressure forces of the fluid in such machines is
applied to
the housing. Hereinafter such structures shall be called rotor machines with
force
closure to the housing.
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Pressure forces acting upon each cover plate from inside the rotor machine
are not balanced from outside by counter forces. At higher pumping pressures
deformation of the cover plates and elements of the housing linking the cover
plates
starts to influence on the quality of face seals. To work with high pressures
the
invention provides for the hydrostatic means of preventing deformation of
insulating
surfaces of the cover plates of the housing.
In one embodiment of the mentioned hydrostatic means Fig.10 face cover
plates of the housing are made of two elements: external load-bearing element
29
taking upon itself pressure forces of the working fluid and internal
functional element
30 being in sliding insulating contact with the corresponding part of the
rotor. Anti-
deformation chamber 31 connected to the pumping cavity via channel 32 is made
between these elements opposite the pumping cavity. Form, dimensions and
location of the anti-deformation chamber are chosen so that to compensate
pressure forces of the fluid on internal functional element 29 of the cover
plates of
the housing from the side of the rotor by pressure forces of the fluid from
the side of
anti-deformation chamber 31. As a result external load-bearing element 29 of
the
cover plate takes upon the pressure forces and deformations caused by them.
While
internal functional element unloaded from pressure forces of the working fluid
is not
a subject to any deformations and keeps the form of the sealing surfaces and
quality
of the seals. Anti-deformation chamber 31 is sealed along the perimeter so
that
deformation of the load-bearing element 29 of the cover plate does not lead to
leakages from this chamber.
The elements linking the cover plates of the housing in rotor machines with
force closure to the housing can be made in two embodiments. The first
embodiment provides for a linking element as a hollow body like a barrel with
a
space between the cover plate that contains a rotor inside Fig.2a, 2b. The
invention
also provides for a housing like a bobbin Fig.2c where linking element 33 of
the
housing passes inside the rotor mounted on bearings 34 and located between
face
cover plates 3 and 5 of the housing, connected via tighten nuts 35 to linking
element
33 of the housing.
Force closure to the rotor.
There is also another embodiment of the hydrostatic means for preventing
deformations of the housing surfaces of the mentioned sliding insulating
contacts for
rotor machines with force closure to the rotor. As the rotor takes radial
components
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of pressure forces of the working fluid in the annular groove it is made with
sufficient
solidity and rigidity.
Machines with force closure to the rotor provide for combination of the
working and supporting cover plates of the housing into an operational unit of
the
5 housing located between the working and supporting parts of the rotor so
that the
working face surface of the working part of the rotor is in sliding insulating
contact
with the surface of the working cover plate of the operational unit of the
housing and
the surface of the supporting face of the supporting part of the rotor is in
sliding
insulating contact with the surface of the supporting cover plate of the
operational
10 unit of the housing.
Operational unit of the housing can be made as an integral part. In such an
embodiment the function of the working cover plate is performed by that face
surface of the operational unit that is in sliding insulating contact with the
working
face surface of the working part of the rotor, and the function of the
supporting cover
15 plate is performed by the opposite face surface of the operational unit
being in
sliding insulating contact with the surface of the supporting face of the
supporting
part of the rotor. Corresponding parts of such operational unit of the housing
hereinafter shall be considered as working and supporting cover plates of the
housing.
20 The invention provides that the assemblage of the rotor elements described
above providing kinematical connection of the working and supporting parts of
the
rotor in such an embodiment includes a rotor linking element to which the
stretching
pressure forces of the working fluid tending to force out working and
supporting
parts of the rotor from the cover plates of the operational unit of the
housing and
25 from each other are transferred. The mentioned linking element may be
connected
to both parts of the rotor via force chambers of variable length or it can be
connected via the mentioned force chambers to one of the parts of the rotor
and
rigidly coupled with the other part of the rotor.
In one of the embodiments of the invention the rotor has a form similar to a
30 bobbin Fig.2d, 2e, 2f, 2g with two separated parts of larger diameter 36
connected
by the medium part of smaller diameter of rotor linking element 37. The
working
chamber is located on the internal face surface of one or both parts of larger
diameter.
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36
Pumping and suction of the working fluid is realized through the channels in
operational unit of the housing 38. There can be no suction channel for
submersible
embodiments of the pumps. External face surfaces of the operational unit
perform
the same functions as the internal functional elements of the working and
supporting
cover plates of the housing in the pumps with force closure to the housing. At
least
one of them carries a backward transfer limiter and forward transfer limiter
on it.
In such an embodiment of the invention the rotor can be similarly made of
two movable relative to each other parts: working part 1 containing vane
chambers
7 with vanes 8 and annular groove 2, and supporting part 4 containing either
supporting cavities 25 or also an annular groove and vanes for an embodiment
with
two working chambers. First of the mentioned parts of the rotor is rigidly
coupled
with the rotor linking element, for example, it is made as a rigid bobbin, and
the
second one is made as an annular element put on the medium part of the rotor
linking element and connected via force chambers of variable length to the
first one.
Fig.2d presents a machine with the working part of the rotor made as an
annular
element and Fig.2g - with the supporting part of the rotor made as an annular
element.
Fig.2e presents an embodiment of the rotor with two working chambers in
both parts of the rotor and two sets of vanes, one of the parts of the rotor
made as
an annular element. Both cover plates of the housing, that are both face
surfaces of
operational unit of the housing 38 have forward 15 and backward 21 transfer
limiters. In this case the definitions "working" and "supporting" with regard
to the
parts of the rotor and cover plates of the housing are also relative and used
to
preserve common terminology.
Fig.2f presents an embodiment of the rotor with separate carrying element 39
of the rotor made as a bobbin. Working 1 and supporting 4 parts of the rotor
are
mounted on the middle linking part of such carrying element. In this case
force
chambers of variable length 6 can be made between the internal faces of this
third
carrying element and both or one part of the rotor, either working or
supporting.
Stretching components of the pressure forces of the working fluid in such
machines are taken upon either by those parts of the rotor that are rigid
enough or
by those parts of the rotor which deformation do not influence on the
leakages.
For the machines with force closure to the rotor it is difficult to use the
supporting part of the rotor to exchange the working fluid between the working
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37
chamber and the vane chamber due to large length and complicated form of the
inter-rotor channels required for that. Therefore it is convenient to overcome
the
tendency to cavitation in such machines by means of changing the character of
vanes' movement and their form.
Fig.2g presents an embodiment of the machine with the working part of the
rotor made as a bobbin. To locate vanes drive mechanism in such a structure
there
may be used rear face of working part of the rotor 1 and adjacent part of the
housing
40. Vanes 8 are located in vane chambers 7 of working part of the rotor 1 with
a
possibility to rotate around axis 41 parallel to axis 9 of the rotor rotation.
Each vane
has axial ledge 42 passing through the rear face of working part of the rotor
1. Axial
ledge 42 has pivoted arm 43 sliding at the rotor rotation on cam guiding slot
44 and
turning the vane so that in forward transfer area the vane shuts off annular
groove 2,
and in backward transfer area the vane is moved from the annular groove into
vane
chamber 7. Flow of the fluid generated by the turn of the vane does not induce
any
significant pressure drop capable of causing cavitation. The depth of the
working
chamber in such a structure can be increased that will lead to the increase of
the
displacement at the same dimensions. Increasing the ratio of the working
chamber
depth to the diameters of the sealing surfaces of the rotor and of the housing
in its
turn leads to the decrease of the share of the friction losses in total power
and as a
result to higher efficiency of hydro machine.
Operational unit of the housing of the machines with force closure to the
rotor
is under symmetrical compressing pressure forces of the fluid and is balanced
in
general that is an efficient means to prevent deformation of its surfaces of
sliding
insulating contacts. The type of its mounting on the housing should provide
for a
possibility of input-output of the fluid from the working chamber of the pump
and it
should prevent rotation of the operational unit relative to the housing around
the axis
of the rotor rotation (the housing itself can rotate relative to the rack of
complete
hydromechanical system).
To balance the pressure in the cavities between the operational unit of the
housing and the parts of the rotor the machine shall have the channels
connecting
supporting cavities 25 of supporting part of the rotor 4, force chambers 6
inside the
rotor, vane chambers 7 and cavities in the working chamber. These channels can
be made in the rotor passing through the middle rotor linking part. The
preferred
embodiment of the machines with force closure to the rotor provides for
channels
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38
27-1 in operational unit of the housing 38, including forward transfer limiter
and
backward transfer limiter Fig. 5c - 5f. In this case through channels 27-1 in
operational unit of the housing 38 in transfer areas should be made so that to
prevent the flow of the working fluid between the adjacent transferred volumes
and
suction and pumping cavities. It means that vane sealing ledges 17 or bottom
sealing ledges 23 being in sliding insulating contact with the insulating
surface of the
corresponding transfer limiter should fully shut off the mentioned through
channels
27-1 of operational unit 38 passing the corresponding spot, while the channel
in
forward 15 or backward 21 transfer limiter shut off by the surface of the vane
8 or of
the bottom of annular groove 2 from the side of the working part of the rotor
1 is at
the same time shut off by the sliding insulating contact of the surface of
supporting
part of the rotor 4 with supporting cover plate 5 of operational unit of the
housing 38.
The invention also provides for such an embodiment of the machine with the
force closure to the rotor where supporting cavities 25 are made not in the
supporting face of supporting part 4 of the rotor but in the supporting cover
plate of
operational unit of the housing 38 Fig.5c, 5e, 5f. Means of the supporting
cavities
insulation in such an embodiment include partitions between the cavities in
the
housing the character of abutment of which to the supporting part of the rotor
determines leakages between the supporting cavities, and also include
peripheral
insulating surfaces the character of abutment of which to the supporting part
of the
rotor determines the leakages from the supporting cavities to the drainage.
Location, form and area of these supporting cavities on the supporting cover
plate of the operational unit of the housing taking into account the area of
the sliding
insulating contact of the means of insulation of the supporting cavities with
the
supporting part of the rotor and pressure distribution in it are chosen so
that the
pressure forces of the working fluid contained in force chambers of variable
length
tending to press the supporting part of the rotor to the supporting cover
plate of the
operational unit of the housing are substantially balanced by pressure forces
from
the side of the supporting cavities providing just a small pressing of the
supporting
part of the rotor to the corresponding sealing elements of the housing
required for
insulation.
Radial dimension of these cavities are chosen so that to provide the
described substantial balancing of the supporting part of the rotor, and their
arc
dimensions are chosen so that to prevent leakages of the working fluid between
the
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39
neighboring transferred volumes and suction and pumping cavities. It means
that
insulating surfaces of supporting part of the rotor 4 including dams between
channels 27 (Fig.5e) being in sliding insulating contact with the insulating
surface of
operational unit of the housing 38 should fully shut off the mentioned
supporting
cavities 25 of operational unit 38 passing the corresponding spot. In such an
embodiment as presented in Fig.5c, 5f, the surface of the supporting face of
supporting part of the rotor 4 can have no cavities. Mentioned supporting
cavities 25
in the supporting cover plate of the operational unit of the housing are
hydraulically
connected via mentioned channels 27-1 to the adjacent by the angular distance
cavities in the working chamber of working part of the rotor 1 so that each
channel
27-1 made in forward 15 or backward 21 transfer limiter and shut off by the
surface
of vane 8 or of the bottom of annular groove 2 from the side of working part
of the
rotor 1 is connected to supporting cavity 25 that is at the same time shut off
by
sliding insulating contact of the surface of supporting part of the rotor 4
with
supporting cover plate 5 of operational unit of the housing 38.
In a particular embodiment of the invention cross dimensions of channels 27-
1 are close to cross dimensions of supporting cavities 25 or even equal to
them
Fig.5e.
There is another possible embodiment of the machine with force closure to
the rotor made not as a bobbin but as a hollow body (barrel) Fig.2h with rotor
linking
element 37 containing the middle part made as hollow cylinder 45 connecting
separate face parts 46 of the rotor so that inside the rotor there is formed a
space
with operational unit 38 of the housing mounted in it. In this case
operational unit of
the housing is mounted on the housing by means of shaft 47 with the axis
passing
through one of separate face parts 46 of the rotor. The offered solutions for
such
rotor are similar to those for rotor as a bobbin.
It is also possible to connect the supporting and working parts of the rotor
directly by the set of force chambers of variable length 6 Fig.2i made so that
pressure forces of the working fluid contained in them tend to move working I
and
supporting 4 parts of the rotor closer to each other and to balance pressure
forces
forcing them out of operational unit 38 of the housing and from each other.
Due to described possibility of the force chambers of variable length to keep
hermiticity at reciprocal movements of the parts of the rotor including the
tilts, force
chambers in the rotor of such machines, when it is mounted on the working or
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supporting part on the side opposite the operational unit of the housing,
besides it's
main functions also performs a function of preventing deformation of
insulating
surfaces of the corresponding part of the rotor under the influence of axial
components of the pressure forces of the working fluid, similarly to anti-
deformation
5 chambers in the machines with force closure to the housing. So the pressure
forces
deform the external part of the rotor linking element which the force chambers
are
supported by, and which deformation is not significant for insulation.
Structures with force closure to the rotor result in the rotor complication
but
allow for significant simplifying and lightening of the housing structure. It
can be of
10 importance if such a structure is used, for example, as a pumping-motor
unit in two-
engine or multi-engine hydromechanical transmission where both the rotor and
housing should rotate relative to the rack of the aggregate. The location of
the vanes
drive mechanism on the external face of the rotor and changing the character
of
vanes movement makes it possible to increase relative depth of the working
15 chamber and efficiency of the machine and to remove the origins of
cavitation in
vane chambers.
The means of local pressures balancing in the described embodiments of the
invention include a set of the channels in the rotor and in some embodiments
they
also include the channels in the housing, in particular, in the operational
unit of the
20 housing. Depending on the arrangement of the particular embodiment of the
invention the mentioned set of the channels in the rotor includes either
channels
connecting force chambers of variable length to the annular groove of the
working
part of the rotor, or the channels connecting force chambers of variable
length to the
supporting cavities, or the channels connecting the supporting cavities to the
25 annular groove of the working part of the rotor, or a combination of the
listed
channels. The mentioned channels in the rotor can include vane chambers,
channels in the vanes and also channels in the force chambers.
The invention also provides for embodiments with the force chambers of
variable length directly connected to the annular groove Fig.5f or to the
supporting
30 cavities Fig.2j. In the latter case there is provided an embodiment of the
machine
with force chambers of variable length 6 consisting of the containing elements
in the
form of force cavities 14 of working part of the rotor 1 directly connected to
annular
groove 2 of working part of the rotor 1, force cavities 14 of supporting part
of the
rotor 4 directly connected to supporting cavities 25 between supporting part
of the
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41
rotor 4 and supporting cover plate 5 and embedded elements in the form of
connectors 12 placed into the mentioned force cavities. In such an embodiment
means of local pressures balancing include openings 48 Fig.2j in the rotor
formed at
the mentioned direct connection of force chambers 6 to annular groove 2,
channels
26 in connectors 12 and openings 48-1 formed at direct connection of force
chambers 6 to supporting cavities 25. The means of local pressures balancing
in the
embodiment of such a machine with force closure to the rotor include openings
48 in
the rotor formed at the mentioned direct connection of force chambers 6 to
annular
groove 2 and channels 27-1 in operational unit of the housing 38 connecting
annular
groove 2 to supporting cavities 25.
Summary of the offered solution.
Thereby, the essence of the described solutions removing the causes of
dissipative energy losses on friction in face seals and on cavitation and
making the
pumps more reliable is as follows:
The rotor is made of two parts: working and supporting connected via force
chambers of variable length so that the changing length of the force chambers
results in little reciprocal axial movements and tilts of the working and
supporting
parts of the rotor required to provide their sliding insulating contact with
the
corresponding sealing surfaces of the working and supporting cover plates of
the
housing. There are supporting cavities made between the supporting part of the
rotor and supporting cover plate of the housing.
Means of local pressures balancing provide for pressures in all force
chambers equal to the pressures in the corresponding supporting cavities and
cavities of the working chamber independently of the character of abutment of
the
surfaces of all sliding insulating contacts and leakages connected with it.
Due to the
choice of forms, dimensions and location of the force chambers and supporting
cavities there is formed a close to reflection symmetric distribution of
pressure
forces acting upon the opposite faces of both parts of the rotor and thereby
balancing each of the parts separately. The pressing of the parts of the rotor
to the
cover plates of the housing required to provide insulation in face seals and
friction
losses proportional to this pressing can be arbitrary small within a
reasonable range.
The mentioned equality of pressures determining this pressing is not disturbed
by
changing the character of abutment of the surfaces of sliding insulating
contacts, in
particular, by appearance of local defects of the sealing surfaces.
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42
In this case one of the units, either rotor or stator (here mostly called the
housing) is made so that to take upon itself stretching pressure forces of the
working
fluid, at the same time another unit takes upon itself compression pressure
forces of
the working fluid. The elements being deformed under the influence of axial
pressure forces in the unit taking upon itself stretching pressure forces of
the
working fluid are separated by means of passing the pressure from the elements
with flat surfaces providing a sliding insulating contact.
In the pumps with force closure to the housing suction of the fluid into the
vane chambers and force chambers is provided via the channels in the
supporting
part of the rotor and distributing cavity in the supporting cover plate of the
housing.
The mentioned channels have big flow section, cause no significant pressure
drops with the fluid flow and are not subject to the influence of suspended
particles.
External face of the rotor of the pump with force closure to the rotor can be
used to allocate a vanes drive mechanism with rotating type of the vanes
movement
causing no significant pressure drops in the vane chamber.
Detailed description of one embodiment of the offered Invention.
To describe in details the structure and operation of one of the embodiments
of the offered invention we shall consider an embodiment of a rotor sliding-
vane
machine with force closure to the housing in the form of a hollow cylinder (
barrel )
and with one working annular groove.
Rotor sliding-vane machine in the present embodiment of the invention
Fig.1 a, 1 b, 2a, 2b, 9 and 10 comprises two main units: the housing and the
rotor
installed inside the housing with a possibility of rotation.
The rotor contains working part 1 with vane chambers 7 with annular groove
2 of constant rectangular cross-section made on the working face surface of
the
said part and connected to vane chambers 7 holding vanes 8 with through
channels
18.
Housing 40 is made with inlet 49 and outlet 50 ports and with face working 3
and supporting 5 cover plates each consisting of load-bearing element 29 and
internal functional element 30, there are also anti-deformation chambers 31
connected to outlet port 50 and made between the mentioned load-bearing and
functional elements, and suction 28-1 and pumping 51-1 distributing cavities
divided
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by insulating dams (57) made on the functional element of the supporting cover
plate.
The working chamber of the machine is bounded in radial direction by the
internal surfaces of annular groove 2, and in axial direction by the internal
surface of
working cover plate 3 of the housing and by bottom of annular groove 20. In
the
working chamber there are forward transfer limiter 15, backward transfer
limiter 21,
and there are formed suction cavity 28 connected to inlet port 49, and pumping
cavity 51 connected to outlet port 50. Suction and pumping cavities are
connected
to the inlet and outlet ports correspondingly via channels 52, 53 in working
cover
plate 3 of the housing.
To consider the processes occurring in the machine during the transfer of the
working fluid there are recognized four areas: suction area A, forward
transfer area
B, pumping area C and backward transfer area D.
Suction area A corresponds to the location of suction cavity 28, and pumping
area C corresponds to the location of pumping cavity 51. Forward transfer area
B is
located between suction A and pumping C areas. In this area the fluid
contained in
the working chamber between vanes 8 and in the rotor cavities connected to the
working chamber is transferred from suction area A to pumping area C. In
backward
transfer area D part of the fluid from pumping area C is transferred back to
suction
area A.
Forward transfer limiter 15 is mounted on the working cover plate of the
housing, located in the working chamber in forward transfer area B and is in
sliding
contact with the face surfaces of vanes 8 moving into annular groove 2,
thereby
providing a possibility of separating at least one inter-vane cavity 62 by the
vanes
from suction cavity 28 and from pumping cavity 51.
In other embodiments of the present invention the mentioned limiter can be
made movable in axial direction. In case of its axial movement the area of the
cross-
section of the working chamber in forward transfer area changes and therefore
changes the displacement of the machine. To control its axial movement the
machine should have a drive mechanism of the forward transfer limiter. In the
machine of the fixed displacement the mentioned forward transfer limiter can
be
made as flat insulating spot on the working cover plate of the housing.
Backward transfer limiter 21 is mounted on working cover plate 3 of the
housing, located in the working chamber in backward transfer area D, contacts
with
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44
sliding with the rotor means of insulation of the backward transfer, namely
with the
internal surfaces of annular groove 2, and thereby separates suction cavity 28
and
pumping cavity 51 of the working chamber.
Vanes drive mechanism 54 is made as a cam mechanism including mounted
on housing 40 carrier 55 of guide cam slot 44 in which side lobes 56 of vanes
8
slide. Profile of the cam slot determines the character of the axial movement
of the
vanes at the rotation of the rotor. Vanes drive mechanism controls cyclical
movement of vanes 8 relative to working part 1 of the rotor at its rotation so
that
vanes 8 in suction area A axially move out of vane chambers 7 into annular
groove
2 and in forward transfer area B shut off cross section of the working
chamber, and
in pumping area C move out of annular groove 2 into vane chambers 7 and open
cross section of the working chamber in backward transfer area D.
Forward transfer limiter 15 is provided with an unlocking section with slot 63
Fig.1 b. Dimensions and location of the slot are chosen so that to provide
pressure
balancing at the faces of the vane by the beginning of its axial movement out
of the
annular groove into the vane chamber.
Other embodiments of the present invention can have a different character of
the vanes' movement. Any kinds of the vanes' movement relative to the rotor
leading to cyclical change of the degree of shutting off the cross section of
the
annular groove by the vane are admissible. For example, besides structures
with
axial movement there may be structures with radial movement of the vanes, with
rotary movement and with their combination. In the pumps with variable
displacement the mentioned mechanism should be kinematically connected to
axially movable forward transfer limiter in order to provide the change of the
degree
of the vanes moving out of the vane chambers to the annular groove
corresponding
to the change of the area of cross section of the working chamber in forward
transfer area.
The rotor also comprises supporting part 4 Fig.1 b with supporting cavities 25
on the external face. The mentioned supporting cavities are insulated by flat
surfaces of means of the supporting cavities insulation, namely, insulating
dams 57
and peripheral face seals 58, due to the sliding insulating contact of the
mentioned
flat surfaces with flat insulating surfaces of functional element 30 of
supporting cover
plate of the housing 5.
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The mentioned working and supporting parts of the rotor are mounted on
bearings 34 on working 3 and supporting 5 cover plates of the housing
correspondingly and connected to inlet shaft 60 by means of joints 61 so that
they
rotate synchronously but have a possibility to make little axial movements and
tilts
5 relative to each other at least sufficient for providing sliding insulating
contact of the
both mentioned parts of the rotor with the corresponding cover plates of the
housing.
The rotor also comprises force chambers of variable length 6 located
between working part of the rotor 1 and supporting part of the rotor 4. The
10 mentioned force chambers in the present embodiment of the machine are
formed by
force cavities 14 made on the surfaces of working 1 and supporting 4 parts of
the
rotor looking at each other and cannular connectors 12 mounted with
possibility of
sliding in the mentioned force cavities. Cannular connectors have sealing
shoulders
13. Their form, location and dimensions are chosen so that to provide
insulation of
15 force chambers within the whole range of axial movements and tilts of the
supporting part of the rotor relative to the working part of the rotor. There
are springs
59 installed in force chambers of variable length to provide sealing in case
of no
pressure. The same change of the length of all force chambers 6 leads to
forward
reciprocal movement of working 1 and supporting 4 parts of the rotor while
different
20 change of the length of different force chambers 6 leads to reciprocal
tilts of working
1 and supporting 4 parts of the rotor.
Means of local pressures balancing in the present embodiment of the
machine include vane chambers 7 and channels 18 in the vanes via which each of
the mentioned cavities of the working chamber 28, 51 and 62 is connected to
force
25 cavities 14 of working part of the rotor, channels 27 via which force
cavities 14 of the
supporting part of the rotor are connected to supporting cavities 25, and
channels
26 in connectors 12. The mentioned channels have small hydraulic resistance so
that at flow rate of the working fluid through any of the mentioned channels
corresponding to maximum admissible leakage from the working chamber the
30 pressure drop in this channel is substantially, i.e. hundreds times less
than nominal
pumping pressure. So from the point of view of the balance of pressure forces
acting upon the parts of the rotor at any angle of the rotor rotation the
local
pressures in the supporting cavity and in the force chamber and cavity in the
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46
working chamber connected to it are substantially equal at any admissible
level of
the leakages from any mentioned cavity.
The faces of the vanes moving into the annular groove have vane sealing
ledges 17 shutting off inter-vane cavities of forward transfer 62 at sliding
contact
with the forward transfer limiter.
The bottom 20 of annular groove 2 has bottom sealing ledges 23 that at
sliding contact with the backward transfer limiter are shutting off bottom
unloading
cavities 22 connected to force chambers 6 via channels 18 in the vanes and
vane
chambers 7. The area of the sliding surface of bottom sealing ledge 23 in the
present embodiment of the machine is equal to the area of the sliding surface
of
vane sealing ledge 17.
The number of supporting cavities 25 is equal to the number of vane
chambers 7. Supporting cavities 25 are oval, their radial width is equal to
the radial
width of annular groove 2. Sum of the areas of supporting cavities 25 and dams
57
is equal to the area of the bottom of annular groove 2. At that the areas of
the sliding
surfaces of dams 57 are equal to the areas of sliding surfaces of bottom
sealing
ledges 23, and the areas of sliding insulating contacts of peripheral face
seals 58
with insulating surfaces of supporting cover plate of the housing 5 are equal
to the
corresponding areas of sliding insulating contacts of working part of the
rotor 1 with
working cover plate of the housing 3. Supporting cavities 25 are located
opposite
annular groove 2, and dams 57 are located opposite bottom sealing ledges 23.
The number of force chambers of variable length 6 is equal to the number of
vane chambers 7. Cross section of force chambers of variable length 6 has
round
shape. The sum of cross sections of force chambers 6 exceeds the sum of the
area
of the bottom of annular groove 2 and half of the area of the sliding
insulating
contact of the working part of the rotor with the working cover plate of the
housing
by the value sufficient for small, enough for insulation, pressing of working
1 and
supporting 4 parts of the rotor to the corresponding cover plates of the
housing 3
and 5.
Operation of the described embodiment of the machine.
Let us consider the operation of the rotor sliding-vane machine described
above operating as a pump and the balance of pressure forces of the working
fluid
acting upon the working and supporting parts of the rotor. The same arguments
are
valid for a hydromotor amended for the difference in hydro tightening of the
vanes
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47
described above. To consider a complete cycle consisting of suction, forward
transfer, pumping and backward transfer we shall consider single transferred
volume formed by the cavities connected at the transference to the vane
chamber of
one chosen vane. The initial moment of consideration corresponds to the
position of
the chosen vane at the beginning of the suction area. Balance of the forces
acting
upon the parts of the rotor shall be considered based on the steady-state
local
pressures in the cavities of the transferred volume and in the sealing
clearances
adjacent to it. The present pump operates as follows:
At the initial moment of the cycle equal to one turn of the rotor the chosen
vane is located on the border of the backward transfer area and suction area.
When input shaft 60 Fig.2a is rotating the torque is transferred via joints 61
to
working 1 and supporting 4 parts of the rotor causing their rotation relative
to
housing 40.
At the rotation of the rotor Fig.1 a, 2b, 9 side lobe 56 of vane 8 slides
along
the guide cam slot 44 of such a form that in suction area A the vane moves out
of
vane chamber 7 into annular groove 2. The working fluid via channel 52 and
suction
distributing cavity 28-1 in supporting cover plate 5, supporting cavity 25 and
channel
27 in the supporting part of the rotor, and via cannular connector 12 in force
chamber 6 fills up the space in vane chamber 7 vacated by the moving vane 8.
Besides that, part of the fluid goes to the vacated volume in the vane chamber
via
channel 18 Fig.9 in vane 8 and via similar channels in other vanes connected
to the
suction distributing cavity. The mentioned fluid filling up the space in the
vane
chamber 7 vacated by the vane 8 moving out of the vane chamber compensates the
volume replaced by the part of the vane 8 in annular groove 2. Presence of
distributing cavity 28-1 in supporting cover plate 5 of the housing and of
channels 52
and 27 decreases hydraulic resistance of the duct via which the fluid fills up
the
vane chamber 7 at the vane 8 moving out, decreasing in that way the tendency
of
the pump to cavitation and makes it possible to increase maximum self-suction
speed.
While the working fluid in the force chamber is under low or zero pressure the
force cavities of the force chamber are slided apart by the springs 59 Fig.2a.
Protruded vane in forward transfer area B contacts with sliding by its sealing
ledge
17 to forward transfer limiter 15 and closes from behind inter-vane cavity 62
Fig.9 of
forward transfer that is shut off by the sealing ledge of the previous vane 8'
from the
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front in the direction of the rotor rotation. Insulating dam 57 of the
supporting part of
the rotor in forward transfer area has a sliding contact with flat insulating
dam 64 of
the supporting cover plates of the housing and closes from behind the
supporting
cavity 25 that is shut off by the previous dam 57' from the front in the
direction of the
rotor rotation. The insulation of force chamber of variable length 6 is
provided by
sealing shoulders 13 of cannular connector 12. So current transferred volume
65
including the volumes of inter-vane cavity 62, channel 18 in vane 8, vane
chamber
7, cavities 14 and channel 26 of force chamber 6, channel 27 and supporting
cavity
25 in supporting part of the rotor 4 becomes closed in the forward transfer
area.
At the rotor rotation this current transferred volume 65 travels in forward
transfer area B from suction area A to pumping area C. Due to the inter-
leakage of
the working fluid between the adjacent transferred volumes as the mentioned
transferred volume travels towards the pumping area the pressure in it
increases.
The character of the pressure increase depends on the speed of rotor rotation,
outlet pressure, character of abutment of the surfaces of insulating contacts,
i.e.
clearances between all sealing surfaces in the forward transfer area and
presence
of local defects on them and can be different for different transferred
volumes. But
due to the means of local pressures balancing as a manifold of channel 18 in
vane
8, channel 27 in the supporting part of the rotor and channel 26 in cannular
connector 12 the pressure in all the mentioned cavities 62, 18, 7, 14, 27 and
25
forming the chosen transferred volume, is the same. As the pressure of the
fluid in
force chamber 6 included into the considered transferred volume increases the
forces of hydrostatical pressure of the fluid become more important in the
balance of
the forces acting upon the working and supporting parts of the rotor and the
role of
springs 59 Fig.2a becomes less significant. Dimensions of annular groove 2,
area of
the sliding insulating contact of the working part of the rotor with the
working cover
plate of the housing determined in this case by the width of sealing shoulders
66
Fig.1 b of the working cover plate of the housing, and dimensions of force
chambers
6 are chosen so that pressure forces of the fluid acting upon the working part
of the
rotor from the side of inter-vane cavities 62 are smaller than the pressure
forces
from the side of force chambers 6 by a small chosen value in order to provide
minimum required pressing of working part of the rotor 1 to working cover
plate of
the housing 3. The mentioned value of the pressure forces difference is chosen
taking into account friction forces in the force chambers and in the joint
couplings of
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the parts of the rotor with the shaft. Similarly, dimensions and form of
supporting
cavities 25 of supporting part of the rotor 4 and dimensions of sealing
shoulders 67
Fig.1 a of supporting cover plate of the housing 5 are chosen so that pressure
forces
of the fluid acting upon the supporting part of the rotor from the side of
supporting
cavities 25 are smaller than the pressure forces from the side of force
chambers 6
by a small chosen value in order to provide minimum required pressing of
supporting part of the rotor 4 to supporting cover plate of the housing 5.
Mutual
location of inter-vane cavities 62, force cavities 14 and supporting cavities
25 is
chosen so that the moments of the counter pressure forces of the working fluid
acting upon the working and supporting parts of the rotor are minimized.
Therefore
pressure forces acting upon the working part of the rotor from the side of
inter-vane
cavities and from the side of the force chambers are substantially balanced,
i.e.
mutually balance each other except a small pressing required for duly face
sealing
from the side of the force chambers to the working cover plate of the housing.
Pressure forces acting upon the supporting part of the rotor from the side of
the
supporting cavities and from the side of the force chambers are substantially
balanced in a similar way.
At the end of the forward transfer area sealing ledge 17 of the previous vane
8' moves to the unlocking section of forward transfer limiter 15. At the same
time
the previous partition 57' of supporting cavity 25 of the chosen transfer
volume is
shifted from insulating dam 64 to the zone of pumping distributing cavity 51-1
of
supporting cover plate of the housing 5. Here the chosen transferred volume is
connected to the pumping area.
Passing pumping area C all the cavities of the chosen transferred volume
and insulating dams between supporting cavities 25 of supporting part of the
rotor 4
are under pumping pressure. Due to the aforesaid properties of force chambers
6
and supporting cavities 25 and sealing shoulders 67 and 66 Fig.1 a, lb on
supporting 5 and working 3 cover plates of the housing, pressure forces acting
upon
the working part of the rotor from the side of inter-vane cavities 62 and from
the side
of force chambers 6 as well as pressure forces acting upon supporting part of
the
rotor 4 from the side of supporting cavities 25 and from the side of force
chambers 6
in pumping area C also mutually balance each other except for a minimum
required
pressing of the parts of the rotor to the corresponding cover plates of the
housing.
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Due to such mutual balancing the working and supporting parts of the rotor
are not subject to axial deformations and keep flat form of the sealing
surfaces.
Pressure forces of the fluid are transferred via anti-deformation chambers 31
to external load-bearing elements 29 of the working and supporting cover
plates of
5 the housing as their deformation influences the leakages less than the
deformation
of the corresponding functional elements 30. Such functional elements take
just a
minor part of pressure forces required for pressing to the load-bearing
element.
Their sealing surfaces remain flat and provide for insulation.
As the chosen vane passes pumping area side lobe 56 of the vane slides
10 along guide cam slot 44 of such a form that the vane in pumping area C
moves out
from annular groove 2 into vane chambers 7. At this time the working fluid via
channels 18 in vanes 8 and via channels 26 in cannular connectors 12 is
displaced
to outlet port 50 from the space in vane chamber 7 occupied by the moving out
vane
8 compensating the volume vacated by the vane in the annular groove.
Therefore,
15 the pump displacement does not depend on the vane size.
Coming to backward transfer area D the chosen vane moves into the vane
chamber completely. Bottom sealing ledges 23 in annular groove 2 adjacent the
chosen vane from the front and from behind relative to the direction of the
rotor
rotation move from the pumping area to the backward transfer area and form a
20 sliding contact with the surface of the backward transfer limiter there,
thus closing
bottom cavity in the annular groove. Insulating dam 57 of supporting part of
the rotor
4 is in sliding contact with flat insulating dam 64 of the supporting cover
plate of the
housing in the backward transfer area and closes from behind supporting cavity
25
closed from the front at the direction of the rotor rotation by the previous
insulating
25 dam 57'. The insulation of force chamber of variable length 6 is provided
by sealing
shoulders 13 of cannular connector 12. Thereby, recurrent backward transfer
volume 68 including the volumes of bottom unloading cavity 22, channel 18 in
vane
8, vane chamber 7, cavities 14 and channel 26 of force chamber 6, channel 27
and
supporting cavity 25 in supporting part of the rotor 4 is closed in the
backward
30 transfer area.
At the rotation of the rotor this current backward transfer volume 68 moves in
backward transfer area D from pumping area C to suction area A. Due to the
inter-
leakage of the working fluid between adjacent transferred volumes as the
mentioned
transferred volume travels towards the suction area the pressure in it
decreases.
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The character of the pressure drop depends on the speed of the rotor rotation,
difference of the pumping and suction pressure, character of abutment of the
surfaces of insulating contacts, i.e. clearances between all sealing surfaces
in the
backward transfer area and presence of local defects on them, and it can be
different for different transferred volumes. But due to the means of local
pressures
balancing as a manifold of channel 18 in vane 8, channel 27 in the supporting
part
of the rotor and channel 26 in cannular connector 12, the pressure in all the
mentioned cavities 22, 18, 7, 14, 27 and 25 forming the transferred volume is
the
same.
Due to the aforesaid properties of force chambers 6 and supporting cavities
25 in supporting part of the rotor 4, and sealing shoulders 67 on supporting
cover
plate of the housing 5, pressure forces acting upon supporting part of the
rotor 4
from the side of supporting cavities 25 and from the side of force chambers 6
in
backward transfer area D also mutually balance each other except for a minimum
required pressing of the supporting part of the rotor to the supporting caver
plate of
the housing.
Sizes of bottom sealing ledges 23, sealing shoulders 66 of the working cover
plate of the housing and force chambers 6 are chosen so that pressure forces
of the
fluid acting upon the working part of the rotor from the side of bottom
unloading
cavities 22 are smaller than the pressure forces from the side of force
chambers 6
by a small chosen value in order to provide minimum required pressing of the
working part of the rotor to working cover plate of the housing 3. Mutual
location of
bottom unloading cavities 22 and of force cavities 14 is chosen so that the
moments
of the said counter pressure forces of the working fluid acting upon the
working part
of the rotor are minimized.
Therefore, no matter in which area of the working chamber the chosen vane
is, the pressures in its vane chamber and in the force chamber and the
supporting
cavity of the supporting part of the rotor connected to its vane chamber are
equal to
the pressure in that cavity of the working chamber which they are connected to
via
the channel in the vane.
Forms, size and location of force cavities of the force chamber and
supporting cavity taking into account the means of insulation of the
supporting cavity
are chosen so that at the mentioned equality of pressures the forces acting
upon
each part of the rotor from the side of the force chambers exceed the forces
acting
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upon it from the side of the corresponding cover plate of the housing by a
value
required for pressing of the sealing surfaces of this part of the rotor to the
sealing
surfaces of the functional element of the corresponding cover plate of the
housing.
Friction losses of power in the face sealings are determined by the mentioned
value of the force of pressing of the parts of the rotor to the functional
elements of
the corresponding cover plates of the housing that can be chosen small.
Appearance of local defects on the sealing surfaces due to wear, for example,
and
contamination of the working fluid with the suspended particles do not lead to
increase of the mentioned force of pressing. Hydraulic resistance of the
channels
determining pressure drop in the vane chamber and maximum self-suction speed
can be chosen on the basis of the required working speed of the rotor
rotation.
