Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02890480 2015-05-07
WO 2014/083364
PCT/GB2014/050035
ROTARY MACHINE
BACKGROUND OF THE INVENTION
Many different kinds of rotary engines and compressors are known. It has long
been the goal to replace reciprocating compressors and engines with rotary
machines, however certainly in the case of engines, very few have become
successful and widely used today.
In the field of rotary engines, the design which has had most development and
use is the well-known Wankel engine. However this suffers from a number of
problems, one of which is wear issues with the internal rotor seals, and
another is
that it is not a true rotary machine, in that there are still eccentrically
moving parts
which generally requires there to be two counterbalanced rotors, or use made
of
rotating counterweights. Furthermore, the location of the tip seals on the
inner rotor
means that these cannot be replaced without stripping the entire engine down.
It is possible to use a Wankel design and to spin both the inner rotor and the
outer casing axially, thus having no eccentric components, as in the very
first
version, the DKM engine. However with this design the sealing points are on
the
inner rotor, which means that the sliding surface containing the inlet and
exhaust
ports must be in the shell or casing. This means that the ports and ducts
which the
sealing points sweep past to control the fluid transfer must be located in the
shell. It
is difficult to make the sealing arrangements necessary to get the gases from
the
ducts on the rotating shell to the outside of the engine.
Various designs of rotary engines and compressors have been disclosed, which
have two rotors spinning on offset parallel axes. Examples of these are
GB764719,
DE2916858, FR1124310 and DE3209807. Taking first GB764719, this design
discloses ducts to transfer fluid to and from the working chambers, with the
ducts
located within a shaft of the machine. However the ducts extend from the
working
chambers through the rotor, and then into the substantially stationary shaft,
which
requires a sealing arrangement between these two components. In this
SUBSTITUTE SHEET (RULE 26)
CA 02890480 2015-05-07
WO 2014/083364
PCT/GB2014/050035
2
arrangement the control of the fluid to and from the working chambers is by
means
of the rotor rotating about this shaft, meaning that this machine requires
seals both to
create the working chambers (the spaces between the inner and outer rotors)
and
seals to control the flow of fluid to/from the working chambers. In addition,
the ports
and ducts in the inner rotor are bidirectional which can slow the fluid
progress, and
they are also permanently connected to the working chambers thus increasing
the
effective chamber volume and reducing the possible compression ration of the
machine. The other documents mentioned here, DE2916858, FR1124310 and
DE3209807, are all similar with regards to the transfer of fluid to the
working
chambers.
Cooley proposed an engine (US 724994) very similar to the invention here,
using
two axially spinning rotors. In his design the inlet and outlet routes were
via sliding
seals between the shell and the casing which would make this design
problematic
and prone to leakage.
Many other rotary engine designs disclose methods of getting the gases into
and
out of the working chambers, however most have relatively complex ducts
containing
several moving parts, which causes problems with sealing and heat transfer
from hot
exhaust gases.
It is the aim of this invention to overcome some of the problems that
previously
known rotary machines suffer from, that is the difficulty of getting the gases
or
working fluids into and out of the working chambers from the outside of the
machine,
the balancing and mechanical problems of eccentric and reciprocating
components,
seal replacement, insulation of hot gases from component parts and these other
designs' general overall complexity.
SUMMARY OF THE INVENTION
This invention concerns a rotary machine designed to be used as an engine or a
compressor. More specifically, it concerns a machine where the sliding sealing
points are located in the outer casing or shell, and the surface which the
sealing
points slide against forms part of the central rotor, causing the fluid to be
transferred
SUBSTITUTE SHEET (RULE 26)
CA 02890480 2015-05-07
WO 2014/083364
PCT/GB2014/050035
3
via one or more ports on the inner rotor. Thus the control of the fluid to and
from the
working chambers located between the rotor and the shell is by means of these
sealing points moving across the ports, and at least one of these ports is
connected
to a duct in the rotor and rotor shaft which duct is made continuous and
unitary with
the port and is extended to the outside of the machine. In this way the duct
is
unidirectional, meaning that the duct is always either transferring fluid into
the
working chambers, or out of the working chambers, depending on the direction
of
rotation of the machine.
A principal advantage of this arrangement is that the fluid can be transferred
between the port and the outside of the machine via a simple duct in the rotor
and
shaft without the complication of additional control measures, seals or
additional
moving parts. This enables both the rotor and shell to spin axially so making
a true
rotary machine. In instances when this machine is used with hot gases, for
instance
as an internal combustion engine, the simple rotary nature of the rotor shaft,
and the
duct it encompasses, around a stationary axis, means that sealing to a further
duct
or pipe is easy to achieve with a concentric rotary seal, and in addition it
is easy to
insulate the duct against heat transfer into engine components.
Another advantage is that the sealing points can be accessed from outside the
machine enabling easy replacement and opening up the possibility of using
cheaper
or faster wearing materials.
It may be seen that there are several advantages in providing the fluid
control
means directly adjacent to the port and duct, including that the duct is
unidirectional
and therefore the fluid flow can be continuous in one direction rather than
oscillating
back and forth, and that the volume of the duct does not become part of the
working
chamber, which would reduce the maximum compression of the machine.
Thus according to the invention there is a rotary machine comprising:
an inner rotor and an outer shell,
the rotor rotating on a first axis and the shell rotating on a second axis
parallel to
and offset from the first axis,
1 SUBSTITUTE SHEET (RULE 26)
CA 02890480 2015-05-07
WO 2014/083364
PCT/GB2014/050035
4
an external support structure which holds the first and second axes in
alignment to
each other, and wherein the said axes are substantially stationary relative to
the
support structure,
the shell having two or more sealing points on its inner surface which
interact with
the outer surface of the rotor to define two or more working chambers between
the
rotor and the shell,
said outer surface including a fluid transfer port,
a shaft attached to the rotor and concentric with the first axis of rotation,
the shaft containing a duct substantially parallel to the first axis of
rotation, which
duct is connected to a further duct in the rotor and said further duct
connected to
the port,
the duct and further duct together forming a continuous passageway for fluid
from
the port to a point where the shaft interacts with the support structure,
wherein the passageway is continuously open and substantially unobstructed and
rotates about an axis which is substantially stationary relative to the
support
structure,
such that in use the relative rotation of the rotor to the shell causes the
working
chambers to change in size, and whereby the relative movement of the sealing
points across the port controls the transfer of fluid between the port and the
working chambers, and wherein for a given direction of rotation of the rotor
the
fluid is transferred unidirectionally through the passageway between the
working
chambers and the point where the shaft interacts with the support structure
The rotor preferably has an outer surface substantially parallel to the axis
of
rotation of the rotor, and the shell preferably has an inner surface
substantially
parallel to the axis of rotation of the shell
SUBSTITUTE SHEET (RULE 26)
CA 02890480 2015-05-07
WO 2014/083364
PCT/GB2014/050035
The outer surface of the inner rotor is preferably substantially in the form
of an
epitrochoid with one or more lobes, however other suitable shapes may be used
for
the outer surface of the rotor, providing of course that in use the sealing
points of the
shell maintain contact or very close proximity to the surface of the rotor.
Preferably
the inside surface of the shell is also substantially epitrochoidal in shape.
The rotor shaft may be attached to one side of the rotor, or it may extend
right
through the rotor from one side to the other. In another arrangement two
shafts may
be used, one on either side of the rotor.
The rotor and shell are preferably mounted in a frame, structure or casing to
locate the axes of the shell and rotor accurately in relation to each other.
The rotor surface may typically have two lobes and the shell have three
sealing
points, but other arrangements are possible for instance a rotor with three
lobes and
a shell with four sealing points. Many other combinations are possible
generally
using a rotor with one less lobe than there are sealing points on the shell.
The rotor may comprise a second port, second duct, and second further duct
wherein the second duct is preferably located in the opposite end of the shaft
to the
first duct so that in use fluid will enter the machine at one end of the rotor
shaft and
exit at the other.
Alternatively the rotor may have a second fluid transfer port which connects
to a
void within the rotor, which further connects to the outside of the machine
via a duct
within the shell, such that in use the fluid will enter the machine through
the shell
shaft and exit through the rotor shaft, or fluid will enter through the rotor
shaft and
exit through the shell shaft.
The duct in the rotor shaft may connect to a stationary duct, pipe or manifold
attached to the exterior of the machine via a rotary seal.
The duct and further duct forming the passageway may be made to be unitary,
that is to be of one piece and not composed of separately moving parts.
SUBSTITUTE SHEET (RULE 26)
CA 02890480 2015-05-07
WO 2014/083364
PCT/GB2014/050035
6
The shell preferably includes an internal gear wheel, which meshes with an
outer
gear wheel attached to the rotor so as to keep these two parts moving in
correct
relationship with each other and therefore minimising internal wear of the
sealing
points and surfaces.
The sealing points may be comprised movable strips, which may conveniently be
accessed from the outside of the shell, enabling their easy replacement.
With a design using a two lobed rotor, there are preferably provided one inlet
port
and one outlet port at suitable locations on the rotor to enable the machine
to
operate as a four stroke internal combustion engine, or alternatively a
similar two
lobed design may be used as a pump or compressor by providing two inlet ports
and
two outlet ports at suitable locations on the rotor.
When the machine is being used as an engine, spark plugs may be provided
around the periphery of the shell. There may be provided means to add fuel to
and
regulate the air flow into the engine, e.g. an injection system or carburettor
which
may conveniently be attached to the frame holding the rotor and shell, and the
outlet
fluid transfer port and ducts may be connected to an exhaust system.
When in use as an engine the exhaust gases preferably exit the machine via the
passageway in the rotor shaft. The inside surface the passageway may be
provided
with thermal insulation to prevent the hot exhaust gases from heating the
rotor
and/or shaft excessively. The unitary nature of the passageway facilitates the
provision of this insulation.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a cross section of components of an engine perpendicular to the
axes of rotation
Figure 2 shows the engine components as in Figure 1, after an anticlockwise
rotation of the rotor of 90 degrees
SUBSTITUTE SHEET (RULE 26)
CA 02890480 2015-05-07
WO 2014/083364
PCT/GB2014/050035
7
Figure 3 shows a cross section of the engine in Figure 2 in line with the axes
of
rotation
Figure 4 shows a modification of the sealing points
Figure 5 shows a compressor with four ports
Figure 6 shows an engine comprising a rotor with four lobes and a shell with
five
sealing points
Figure 7 shows a modification of a rotor shaft
DETAILED DESCRIPTION
The invention will now be described, by way of example only, with reference to
the accompanying drawings.
Referring first to figure 1, this shows the main moving components 19 of a
four
stroke internal combustion engine according to the invention, for ease of
viewing
shown without the structure which holds these components in place. In this
engine
an inner rotor 1 rotates around an axis 2 within an outer shell 3 which
rotates around
an axis 4 offset from axis 2, the direction of rotation being by the arrows 2r
and 3r.
The rotor in this embodiment has two lobes 40 and the shell has three sealing
points
5. The sealing points are comprised moveable sealing strips 6 with spring
arrangements 7 and retaining plates 8. Both the shell 3 and the rotor 1 rotate
in the
same direction at different speeds in the ratio 2:3 respectively. Due to the
epitrochoidal geometry of the rotor surface and the relative speeds of the
rotor and
shell, the sealing points maintain a sliding gas tight seal with the rotor
surface. The
rotor shaft 9 is cylindrical and encompasses a duct 10 in the centre. The duct
in the
rotor shaft nearest the observer extends to a further duct 11 through the
rotor
terminating at a port 12 (inlet port) in the external surface of the rotor,
this duct,
further duct and port forming a passageway 17. A duct in the shaft which is
furthest
from the observer (not shown) extends to a duct 13 through the rotor and
terminates
at the port 14 (outlet port). This second duct, second further duct and second
port
SUBSTITUTE SHEET (RULE 26)
CA 02890480 2015-05-07
WO 2014/083364
PCT/GB2014/050035
8
forms a second passageway 18. Three working chambers A,B,C are formed by the
interaction of the sealing points in the shell and the rotor surface. One
skilled in the
art will see that in use the rotation of the rotor and the shell causes the
working
chambers to vary in size, which in conjunction with the position of the inlet
and outlet
ports causes gas to be drawn in, compressed, combusted and expanded and then
expelled as in a standard four stroke engine. In this diagram the chamber A
between the rotor and the shell is in the process of expelling gas through the
outlet
port 14, the direction of flow shown by the arrow, and chamber B is drawing in
gas
through the inlet port 12, again the gas flow is shown by the arrow. Chamber C
is at
the fully compressed position for firing. The outer shell may include one or
more
combustion cavities 15 to hold the bulk of the compressed gas. Spark plugs 16
ignite the compressed gases at the point of maximum compression.
Figure 2 shows the rotor and shell as in Figure 1 after the rotor has passed
through 90 degrees of anticlockwise rotation, with a corresponding 60 degrees
of
rotation of the shell. Chamber A has decreased in volume, B has reached
maximum
volume and C is just starting to expand. Thus it can be seen that the rotation
causes
gas flow compatible with a four stroke engine cycle.
Note the location of the two meshing gear wheels on the shell 50 and the rotor
51. These gears ensure that the rotor moves in the correct relationship to the
shell,
preventing contact between the rotor surface and the shell surface (except at
the
sealing points) and reducing the stress and wear to the shell, sealing points
and rotor
surface.
Figure 3 shows a cross section in line with the axes of rotation of an engine
37
with the same relative position of rotor and shell as in Figure 2, and
including
additional components not shown in Figure 2. A support structure 20 locates
the
rotor 21 and the shell 22 in position by means of bearings 23. The rotor is
equipped
with side seals around its periphery 24 which seal against the inside of the
shell 22
(the sealing points of the shell are not shown in this diagram). A port in the
rotor 28
is connected to the duct 27 in the rotor, which extends to the duct 26 in the
shaft 25
and which is parallel to and concentric with the axis of rotation 43 of the
shaft and
the rotor. The duct 26 extends to a point 41 where the shaft interacts with
the
SUBSTITUTE SHEET (RULE 26)
CA 02890480 2015-05-07
WO 2014/083364
PCT/GB2014/050035
9
support structure via a bearing 23, this arrangement of ducts comprising a
passageway e-f for the transfer of fluid between the working chamber A and the
point 41. It may be seen that the passageway is unitary, in that it is bounded
by
parts joined together, and not made of parts moving relative to each other.
The shaft
25 and a continuation of the duct 26 within it extend beyond the point 41 to
where
the shaft terminates at 42. A rotary seal 35 seals the shaft to the support
structure
allowing the duct to further extend to a stationary duct 44 attached to the
support
structure. It may be seen that at points beyond 41 towards 42 the shaft with
its
integral duct is rotating on a stationary axis 43 in relation to, and is
adjacent to, the
support structure, which means that from point 41 onwards away from the rotor
the
transfer of gases to or from the engine may be easily arranged.
A second port 29 is connected to duct 30 in the rotor and duct 31 in the shaft
36,
this arrangement comprising a second passageway for the transfer of fluid
between
chamber B and the point 45 where the shaft 36 interacts with the support
structure,
in this case through being in close proximity to it. The shaft extends beyond
point 45
and the duct is sealed against the support structure with the seal 34.
Thermal insulation 38 is fitted to the shaft 36 to protect it from the hot
exhaust
gases. Additional insulation 39 is fitted to the duct 30 in the rotor. It may
be seen
that as the ducts forming the passageway g-h are unitary and move together it
makes the installation of this insulation around the passageway much easier to
achieve.
A high voltage electrical current is supplied to an electrode 32 which is in
close
proximity to the spark plug 33 at the point when the engine is at the position
of
maximum compression, thus initiating combustion.
Figure 4 shows a variation of the sealing points of the embodiment in Figure
1, in
which the sealing points 60 are contiguous with the shell 61 and achieve the
gas
tight sealing by being maintained in very close proximity to the rotor 62.
Figure 5 shows a compressor which has two inlet ports 70 and two outlet ports
71. This uses the same principal of variable size chambers as the engine in
Figure
SUBSTITUTE SHEET (RULE 26)
CA 02890480 2015-05-07
WO 2014/083364
PCT/GB2014/050035
1, but omits the combustion / expansion cycle and instead performs two
compression cycles for every 360 degree rotation of the rotor.
Figure 6 shows an engine 100 comprising a shell 101 with five sealing points
102,
and a rotor 103 with four lobes 104. In this arrangement it is necessary to
have two
pairs of ports 110, 111. It may be seen that this arrangement creates a well-
balanced rotor both mechanically and in terms of thermal expansion due to the
symmetrical arrangement of the rotor.
Figure 7 shows a modification to the engine shown in Figure 3. The rotor shaft
80
is extended to the outside of the engine. The exhaust gases are expelled
through
this shaft which includes insulation 82 to protect the engine components from
the
heat of the gases. A silencer 81 is fitted to the shaft, and it can be seen
that this
rotates with the shaft.
Figure 8 shows a modification to the engine shown in Figure 3. The rotor 90
includes a port 91 that opens into a void 92. A passageway for fluid extends
from
the port, through the void, and through a series of holes 93 into the shaft of
the shell
94 which is concentric with the axis of rotation of the shell, to the point
where the
shell shaft interacts with the support structure 127. The passageway further
extends
through a duct 95 in the support structure 96, and is sealed by means of seals
97
and 126. A shaft 98 supporting the rotor may be made solid in this embodiment
of
the invention, or may contain a duct as in previous embodiments. On the other
side
of the rotor 90 a second port 120 connects to a duct 121 in the rotor with
thermal
insulation 124, which further extends to a duct in a second rotor shaft 99
also with
thermal insulation 125. This forms a continuous passageway m-n from the port
120
to the point 122 where the shaft interacts with the support structure, and
further
extends to the outlet duct 123. The benefits of this arrangement of the
passageway
m-n, especially when used for the hot exhaust side of an engine, have been set
out
above. The inlet passageway is not continuous and unitary and therefore
requires
more seals to function efficiently, and is in addition more difficult to
insulate, however
it has the benefit of being of larger cross section than m-n and therefore
transfers
gases more efficiently. This passageway p-q is used here to admit cold inlet
gases
into the engine.
SUBSTITUTE SHEET (RULE 26)
CA 02890480 2015-05-07
WO 2014/083364
PCT/GB2014/050035
11
Figure 9 shows a modification to the engine shown in Figure 3. The engine 130
has a shell 131 which has a number of fins 132 formed in its external surface.
These
act as a fan when the shell rotates, drawing air through the vents 133 in the
support
structure, and blowing the air out through the vents 134. The passage of air
across
the shell cools the shell, helped by the increased surface area which the fins
provide.
It can be seen that this is a benefit of rotating the shell of the engine as
it removes
the need for an external cooling system. Also shown is a modification to the
design
whereby the air exiting through vents 134 is passed through the duct 135-136
and
into the air intake passageway of the engine 137. One skilled in the art will
appreciate that this will increase the pressure of the intake air and
therefore give the
engine a higher power output.
Figure 10 shows a view of the shell 131 of Figure 9 viewed along the axis of
rotation, and shows the arrangement of curved radial fins 141. There may be
provided additional fins formed in the support structure (not shown here)
which may
interact with the shell fins 141 to provide additional compression of the air.
SUBSTITUTE SHEET (RULE 26)
