Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02410392 2002-11-22
Reversible pump
This invention relates to mechanical engineering and may be used in high-
pressure reversible
pulseless pumps capable of operating both as motor and pump (hereafter
referred to as pump).
Gaseous and liquid working fluids are applicable.
The well-known high-pressure pulseless pump (RU 2123602) comprises housing
with inlet
and outlet ports, the rotor being mounted in the housing. Channels are
provided in the rotor,
wherein the slide valves are situated, which reciprocate along the rotor in an
axial direction.
Further, the general term displacer will be used instead of the slide valve.
The pump
comprises a mechanism being a plurality of members installed inside the
housing, which sets
an axial mutual position of the displacers in the channels of the rotor, a
working chamber, a
partition, which separates suction and injection spaces, thus preventing
backstreaming of the
working fluid between them. The partition is a special case of one of the
insulating members,
which insulating members imply any of the pump elements that prevent fluid
leaking out of
the pump cavities.
In this particular embodiment of the pump, from one side the working chamber
is restricted
along the axis of rotation of the rotor by the surface of one of the rotor's
ends, which is in a
sliding contact with the partition and which is hereafter referred to as the
first end of the rotor,
and from the other side, by a regulating member which is, in fact, an axially
movable
insulating member. In the radial direction the working chamber is restricted
by the shaft
surfaces and the inner surface of a hollow cylinder, which is mounted inside
the housing and
is not able to rotate with the rotor. The pump also comprises means connecting
cavities at
both sides behind the longitudinally opposite ends of the displacers.
In this particular embodiment of the pump, the means are implemented as a
supporting and
distributing member, which is mounted inside the housing and whose surface is
in a sliding
contact with the second end of the rotor. Furthermore, two disconnected
cavities are provided
in the said end of the supporting and distributing member, to which the
channels in the rotor
accommodating the displacers open. One of the cavities is connected by a
channel with the
inlet port, and another one - with the outlet port. The cavities are located
so that one of the
them is opposite the suction space and communicates via a channel with the
inlet port;
another one is opposite the injection space and is connected by a channel with
the outlet port.
Thus the cavities at both sides behind the longitudinally opposite ends of the
displacers are
_ connected, and thereby the displacer is balanced against the hydraulic
forces of the working
fluid, and the effect of the displacer volume on the stability of the flow and
the capacity of the
pump is avoided. One more widely known practical embodiment of said means may
be an
implementation of channels in each of the displacers so that the channels
connect the cavities
at both sides behind the longitudinally opposite ends of the displacers.
As the closest prior-art a high-pressure reversible pulseless pump (RU 2I
15807) was chosen,
which, as in the above example, comprises housing with inlet and outlet ports,
the rotor being
mounted in the housing. The channels are provided in the rotor, accommodating
the
displacers, which are capable of reciprocating along the rotor's axis of
rotation
(longitudinally). The pump comprises a mechanism installed inside the housing,
which sets a
relative axial position of the displacers in the channels inside the rotor, a
working chamber, a
partition, which separates suction and injection spaces, thus preventing
backstreaming of the
working fluid between them. The partition is, in essence, a particular case of
one of the
insulating members, which members imply and will imply hereafter any of the
pump
members that prevents working fluid leaking out of the pump cavities. In this
particular
CA 02410392 2002-11-22
_2_
embodiment of the pump, from one side the working chamber is restricted in the
axial
direction by the end face of the rotor, which is in a sliding contact with the
partition and is
called here the first end of the rotor, and from the other side, by the inner
surfaces of the
housing facing this end of the rotor. In the radial direction, the working
chamber is restricted
by the surfaces of the shaft and inner surface of the housing. The pump also
comprises means
connecting the cavities at both sides behind the longitudinally opposite ends
of the displacers.
In this particular embodiment of the pump, the above means are implemented as
the
supporting and distributing member mounted inside the housing, whose end is in
a sliding
contact with the second end of the rotor. Furthermore, two disconnected
cavities are provided
in the said end of the supporting and distributing member, to which the
channels in the rotor
accommodating the displacers open. One of the cavities is connected by a
channel with the
inlet port, and another one - with the outlet port. They are located so that
one of the cavities is
opposite the suction space and communicates via a channel with the inlet port,
and another
one is opposite the injection area and is connected by a channel with the
outlet port. Thus, the
cavities at both sides behind the longitudinally opposite ends of the
displaces are connected,
and thereby the displaces is balanced against the hydraulic forces of the
working fluid and the
effect of the displaces volume on the stability of the flow and the capacity
of the pump is
ruled out. One more widely known practical embodiment of aforesaid means may
be the
implementation of channels in each of the displacers so that the channels
connect the cavities
at both sides behind the longitudinally opposite ends of the displacers.
It is an object of the invention to improve the operating parameters of such
pumps and
simplify the manufacturability.
These problems have been solved by a design of the pump, which comprises
housing with
inlet and outlet ports, a rotor with channels, wherein at least two displacers
movable along the
25, rotor axis of rotation (longitudinally), a working chamber, a partition,
separating suction and
injection spaces, insulating members, a member setting relative axial position
of the
displacers, and a mechanism connecting the cavities at both sides behind the
longitudinally
opposite ends of the displacers. According to the invention, the working
chamber is formed
by the surfaces of an annular slot, which is made in the end of the rotor so
that its inner
surfaces restrict the working chamber in the radial direction and are in a
sliding contact with-
the surfaces of the partition. Furthermore, the displacers are located in the
channels provided
in the rotor. The channels are oriented longitudinally and extend in an axial
direction, opening
to the annular slot so that the prolongations of the said channels form
recesses in the inner
surfaces of the annular slot, which restricts the working chamber in the
radial direction (i.e.,
normal to the axis of rotation of the rotor).
The abovementioned features included into the design of the pump provide
technical results,
which improve the operating parameters of the pumps of this type due to the
damping effect,
which appears when the displacers approach the insulating member that
restricts the working
chamber in axial direction. The damping effect prevents destruction and
reduces wear of both
40. the insulating member and the displacers being in contact with each other
which enables the
rotating speed of the pump to be increased.
Furthermore, the vibrations of the displacers caused by the hydraulic forces
of the fluid in the
working chamber are reduced; the noise generated by the displacers is also
reduced and it
becomes possible to reduce the consumption of materials, making the displacers
less elastic
and having lower bending strength for the same working pressure. One more
useful result is
the reduction of internal fluid backstreaming in the working chamber and the
improvement of
., the conditions for the formation of the oil-film wedge between the surfaces
of the partition
and the annular slot.
CA 02410392 2002-11-22
Moreover, due to the radial restriction of the working chamber by the surfaces
of the annular
slot, provided in the end of the rotor, the rotor is relieved from the radial
forces of the working
fluid (unlike that in other types of pumps, e. g. vane pumps, in which the
double-acting pump
operation has to be used to this effect). Consequently, radial vibrations of
the rotor and the
noise arising thereby, as well as the fluid friction on the walls restricting
the working chamber
in the radial direction, are reduced.
All the aforementioned features implemented in the pump's design result in an
increase of the
efficiency and the service life of the pump, making it possible to use self
tightening end seals
and to simplify manufacturing technology with specified tolerances and sizes.
This also leads
to essential enhancement of the resistance to hydraulic hammer and abrupt
pressure jumps.
In common with the other types of pumps, this pump may have a mufti-chamber
design with
several working cycles of the displacers per one rotor revolution and also may
have a number
of annular slots on both sides of the rotor ends accomodating the working
chambers which
may properly communicate with each other according to the pump operating
conditions.
The entity of the invention is apparently described by the accompanying
drawings in the
following figures:
Figure 1 depicts a longitudinal sectional view of the pump
Figure 2 depicts a cutaway perspective view of the rotor showing a displacer
and a push rod.
The pump (Fig. I ) comprises housing 1 with end plates 2 and 3 . Rotor 5 is
mounted inside
housing 1 on shaft 4. Channels b are provided in the rotor 5, wherein the
axially movable
displacers 7 are located. The pump may comprise at least two and more
displacers 7. Annular
cylindrical slot ( 18 in Fig. 2) is provided in the end of rotor 5, which is
located opposite the
end plate 2. Channels 6 accommodating displacers 7 are made in rotor 5 so that
they open to
annular cylindrical slot 18 and form recesses 8 in its inner cylindrical
surfaces. In other
25, words, annular slot 18 is provided in the end of rotor 5 so that it passes
through channels 6 in
rotor 5, wherein displacers 7 are located, the radial width of annular
cylindrical slot 18 being
less than that of displacers 7. In the drawings of the present embodiment of
the pump,
channels 6 reach the end of rotor 5 and form recesses 8 in the inner
cylindrical surfaces of
annular slot 18 throughout its depth. However, in other embodiments of the
pump, channels 6
may not reach the end of rotor 5 at some distance.
The pump comprises partition 9, which separates the injection and suction
spaces. (The
suction space is connected with the inlet port and the injection space is
connected with the
port; these are not shown for the simplicity's sake). The surfaces of
partition 9 are in a sliding
contact with the inner surfaces of annular cylindrical slot 18. Partition 9 is
mounted on end
plate 2 and may form a whole with the end plate. (In some embodiments of the
pump,
partition 9 may be fixed, being axially movable, and may interact with the
means which
clamp the partition to rotor 5). Therefore, the working chamber is restricted
by the inner
surfaces of annular slot 18 and the inner surface of end plate 2.
_, The pump comprises a mechanism setting displacers 7 in relative axial
position in channels 6
of rotor 5. In this embodiment of the pump, the mechanism is made as a closed
cam slot 10 in
the inner cylindrical surface of housing 1. Furthermore, each displaces 7 is
equipped with
push rod 11, which enters in a sliding contact with cam slot lOCam slot 10 is
made so that
displacers 7 located opposite the end of partition 9, are moved into rotor 5
at an equal
distance, and a part of displacers 7 at a distance from partition 9 is pulled
out of rotor 5 and is
in a sliding contact with the inner surface of end plate 2.
CA 02410392 2002-11-22
_ y_
The pump also comprises means connecting the cavities at both sides behind the
longitudinally opposite ends of displacers 7. In this particular embodiment of
the pump, the
means are implemented as a set of channels provided in each displacer 7 in
such a way that
said channels connect the cavities at both sides behind the longitudinally
opposite ends of the
displacers 7. The above-mentioned channels are not shown on the drawing for
simplicity.
However, in general, the means connecting the cavities at both sides behind
the longitudinally
opposite ends of displacers 7, may be implemented in a variety of ways as
well, for example,
using a supporting and distributing disk, which is described in the closest
prior-art of the
invention (or using a plurality of said means). This supporting and
distributing disk may be
installed to be movable along the longitudinal direction of rotor 5.
Furthermore, the pump is designed so that the surfaces of the end of rotor S,
wherein annular
cylindrical slot 18 is provided, which are located at dii~erent sides of
annular cylindrical slot
18, are in a sliding contact with the opposite end faces of seals 12, which
are located on the
inner surface of end plate 2 and may be integral with it. This makes it
possible to reduce fluid
leaking out of the working chamber, because the working chamber becomes sealed
over the
end faces, and to reduce wear of the partition end face, which is in a sliding
contact with the
rotor, due to an enlargement of the contact area between the rotor and
insulating members of
the Bump.
In this embodiment of the pump, seals 12 are implemented as two hollow
cylinders, mounted
in annular slots 13, which are made concentric in the inner wall of end plate
2. These hollow
cylinders are mounted so that their cylindrical surfaces facing each other are
in a contact with
the surfaces of partition 9, which are located outside of annular cylindrical
slot ( 18 in Fig.2)
made in the end face of rotor 5.
This substantially simplifies the manufacturability of partition 9 and its
mounting guides
(especially, in the embodiment with an axially movable partition and with a
variable
displacement).
The hollow cylinders are maunted in annular slots 13 and are movable along the
axial
direction of rotor 5. This enables the hollow cylinders to follow the axial
movement of rotor 5
(if the pump is equipped with proper means for the axial movement of the
cylinders), being
permanently in contact with it. This consequently enables stable sealing of
the working
chamber to be obtained during vibrations and the axial shifts of the rotor,
and the thermal
expansion and wear caused by friction of the pump components to be
compensated. The
means of the axial cylinder movement are implemented as follows: at least one
pass-through
channel 14 is made in these hollow cylinders, which extends from the cylinder
end facing the
rotor up to annular slot 13, wherein the cylinder is mounted. By varying the
cross-sectional
area and the position of channels 14 at the cylinder ends, the optimal force
clamping said
cylinders to rotor 5 can be chosen, thus optimizing the backlash and leaking,
thereby reducing
the friction wear of the contacting surfaces.
The second end of rotor 5 is in contact with end plate 3. Slot 15 is made in
the inner surface of
end plate 3, wherein at least one seal 16 movable along the axis of rotor 5 is
mounted. In this
particular embodiment of the pump, two seals 16 are mounted in end plate 3,
both having
pass-through channel 17, which extends from the end of the seal 16 facing the
end of rotor 5
up to annular slot 1 S, wherein seals 16 are located.
Figure 2 depicts a cutaway perspective view of rotor 5 with one displacer 7
and push rod 11 to
demonstrate annular slot 18 and recesses 8 on the inner surface of the rotor.
The pump operates as follows.
CA 02410392 2002-11-22
After starting the pump, while rotor 5 is rotating, push rods 11 start to
slide within closed cam
slot 10 and to reciprocate along the axis of rotation of rotor 5, thereby
moving displacers 7.
Cam slot 10 is made so that the movement of displacers 7 per one revolution of
rotor S is
characterized by the following cycle: displaces 7, which is opposite the end
of partition 9, is
pulled into rotor 5 and does not move along its axis of rotation. As displaces
7 moves away
from partition 9, it starts being drawn out of channel 6 in rotor 5 to the
cylindrical annular
slot's cavity 18, and then sliding along the surfaces of recesses 8 (which are
the additional
guides for the displaces), and then, at some instant displaces 7 touches the
inner surface of end
plate 2. After that, displaces 7 slides with its end along the inner surface
of end plate 2 without
axial movement relative to rotor 5. As displaces 7 approaches partition 9, it
starts being
gradually pushed into rotor 5, until it passes partition 9 being pushed into
rotor 5 up to the
end. While sliding on the inner surface of end plate 2, displaces 7 separates
the injection and
suction spaces in the cylindrical annular slot 18.
In a general embodiment of the pump, a segment of end plate 2 over which
displacers ? slide
may be implemented as an axially movable insulating member (variable
displacement pump
embodiment).
The working fluid, confined between two neighboring displacers land also found
in channels
6, wherein the displacers 7 are located, starts to be transported from the
suction to the
injection space, wherein the low and high working pressure areas are produced,
which are
respectively connected with the inlet and outlet ports (the process is
described in more detail
the prior art patent).
The working fluid tends to stream through the backlashes between the
insulating members
from the injection to the suction space. In cylindrical annular slot l8the
injection space is
separated from the suction space by partition 9 and displaces ? whose end is
in a sliding
contact with the inner surface of end plate 2.
The pressure of the working fluid, which is in the injection space, tends to
move a part of
displaces 7 pulled into cylindrical annular slot 18 towards the suction space,
thus tending to
bend and deform said displaces ?. However, recesses 8 accomodating the part of
displaces ?
pulled into cylindrical annular slot 18 prevent the deformation and bending of
displaces 7.
Recesses 8 act as additional guides for displacers 7, preventing bending and
vibration of
displacers 7 by the fluid pressure in the working chamber (with especial
strength the effect is
exhibited in the embodiment with cylindrical displacers 7). Accordingly,
aforementioned
effect reduces the noise generated by displacers ? and enables the manufacture
of displacers
7with lower material consumption, shorter in length, less elastic and stiff,
for the same
3S working pressure. Furthermore, it allows reducing the dimensions and the
weight of the pump
.. in comparison with the prior-art.
On more useful result of the presence of recesses 8 in the inner surfaces of
cylindrical annular
slot 18 is the reduction of the backstreaming and the relaxed requirements for
the tolerance of
displacers ? for fitting the shape of channels 6; displacers 7 are clamped to
the surfaces of
recesses 8 by the fluid pressure, thereby providing better sealing between the
surfaces of
displacers 7 and recesses 8. Furthermore, since the fluid passes through the
segments with
different cross-sectional areas, the sealing produced by partition 9 between
the suction and
.. injection spaces is improved as well as for the oil-film wedge formation
between surfaces of
partition 9 and annular slot 18 accommodating partition 9.
Besides, due to the radial restriction of the working chamber by the surfaces
of annular slot
18, provided in the end face of rotor 5, rotor 5 is relieved from the radial
forces of the
CA 02410392 2002-11-22
working fluid (in contrast to many other kinds of pumps, e.g. vane pumps, in
which the
double-acting pump operation is used to this effect). Consequently, radial
vibrations of the
rotor, and the noise and instability of the rotation of rotor 5 arising
thereby, as well as the
fluid friction on the walls restricting the working chamber in the radial
direction and losses
due to the friction of displacers 7 on these walls, are reduced.
Recesses 8 on the surfaces of cylindrical annular slot 18 produce the damping
effect and
allow it to be controlled (which is adjusted by selecting appropriate
dimensions and a depth of
recesses 8). The damping effect is observed while displacers 7 approach the
inner surface of
end plate 2restricting the working chamber in the axial direction. The damping
effect arises
due to prevailing backstreaming of the working fluid along recesses 8 (while
they are
connected with the low-pressure areas in the pumping chamber) from the high-
pressure areas
in the pumping chamber, while the displacer approaches the inner surface of
end plate 2 and
shuts aforementioned recesses 8. At that moment, the working fluid is
compressed and tends
to move displacer 7 away, thereby preventing its end from an abrupt impact on
the inner
surface of end plate 2. (This effect is exhibited especially strongly in the
embodiment of the
pump, in which displacers 7 are provided with the protrusions at their ends
(not shown for the
simplicity's sake), facing end plate 2 and located in the recesses. In this
case, the protrusions
primarily shut recess 8, producing a closed space inside it; hence the damping
effect depends
on the dimensions and shape of the protrusions).
The damping effect prevents destruction and reduces wear of both the inner
surface of end
plate 2 and displacers 7 which are in a contact with the end plate; this
allows the rotating
speed of the pump rotor 5 to be increased.
Seals 12 are implemented as two hollow cylinders, mounted in annular slots 13
and axially
'' movable along the axis of rotor 5, following possible axial shifts of rotor
5, being
permanently clamped to the rotor. The clamping is due to the fact that the
working fluid,
flowing from the injection space of the pump into the backlash under the end
faces of seals 12
clamped to rotor 5, tends to force out seals 12 from the rotor. In this case,
the working fluid
flows under pressure from the backlash, through channels 14, into annular
slots 13, thus
balancing the fluid pressure in channel 14 and annular slot 13. Since the
whole area of seal 12
is under the working fluid pressure from annular slot 13, whereas from the
rotor side the
pressure acts near the injection space of the pump only, the optimal force,
clamping the rotor
S to seals 12 implemented as cylinders, is obtained by a proper selection of
the cross-sectional
area and the location of channels 14 at the ends of seals 12. Furthermore, by
connecting
annular slots 13 with a throttle (not shown on the drawings for the
simplicity's sake) and by
adjusting the working fluid flow through the throttle, it is possible to
optimize the backlash
between seals 12 and end faces of rotor 5 contacting with them.
The operation of seals 16 is similar to that of seals 12.
w It should be noted, that the pump is generally manufactured so that all the
members,
contacting with end faces of rotor 5 (as well as partition 9) may be designed
axially movable
~0 and comprising means of self tightening to the end faces of rotor 5,
similar to the means of
the axial movement of seals 12.
It should be also clarified that the rotation of the rotor is always
referenced relative to the
housing of the pump, no matter on which device the housing may be mounted to
provide
rotation of the rotor relative to the housing. In many practical cases of the
pump usage, the
pump's member referred to as housing may be mounted on the rotating shaft of
the given
device, whereas the pump's member called the rotor may be mounted on a frame
or other
rotating shaft of the same device.
