Note: Descriptions are shown in the official language in which they were submitted.
1~658;~3
~his invention relates in general to rotary en-
gines and in particular xelates to rotary engines which
operate as either a motor powared fxom a source of
pressurized 1uidj such as a gas, or as a pump for devel-
~pin~ fluid pressure,
Vaxious types of rotary engines have been sug-
gested or designed and built for operation as either fluid
moto~s or pumps. Positive displacement rotary engines
employ the use o~ pistons, vanes or other elements which
`~ move in fluid-tight sealing relationship with a housing
or chamber wall for confining the working fluid. Engines
of this type possess inherent limitations in their speed
and efficiency of operation, complexity and cost of ~on-
struction and maintenance, high starting friction, and
wear on the moving parts, particularly the seal elements.
Many of these engines also cannot be dynamically balanc;ed
and this further increases the problems of design, engine
life, maintenance and opexating power requirements. Pre-
vious air motors have an effective power limit because
large rotors cannot run at the higher speeds.
It is recognized that turbine engines solve many
of the foregoing problems in that the tuxbine engine i9
d~namically balanced, ~an xun at very high speeds, and has
a ~elatively long life and low maintenance requir~ments.
~Iowever, turbine engines posse5s certain limitations, in-
aludin~ greater design and construction costs, such as for
fabricating the turbine blades. In addition, turbine en-
gines are inherently "leaky fluid" engines and therefore
must be operated at relatively high speeds to attain
acceptable efficiencies. The simple turbine engine a~so
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~ ;S~23
is not readily reversible in operation.
It is a general object of the invention to provide a low-friction, -
controlled leakage rotary engine which is a hybrid form of positive displace-
ment and turbine engine designs.
The invention provides a rotary engine comprising the combination
of a housing formed with an annular chamber concentric with a first longitu- ~
dinal axis, means forming inlet and outlet ports in the housing for directing -
a working fluid into and from the chamber, a piston support member mounted
within the housing for rotation about the first axis and with one end of the -~,
chamber being exposed to the support member, three circumferentially spaced-
apart pistons carried by the support member, each piston projecting longitu-
dinally from the support member into the chamber and being spaced from the
chamber walls with a minimal clearance which is sufficient to direct controlled
leakage of fluid therethrough to the volume ahead of a pressure-active piston
which is exposed to the inlet port whereby the pressure differential across
such piston is insubstantial so as to minimize further fluid leakage past
said clearance, a blocking valve positioned across the chamber between said
inlet and outlet ports, said valve being mounted for rotation about a second
axis parallel with said first axis, said valve being formed with a recess of
a size sufficient to substantially envelope the pistons, and means for
rotating the valve about the second axis in timed relationship with rotation
of the support membcr whereby the pistons carried thereby move through the
recess in the valv~ while the latter blocks substantial communication of
fluid therethrough between the inlet and outlet ports.
The engine does not employ sliding surfaces between the piston,
roto~ and housing so that friction, heat generation, and wear are reduced
whereas lubrication of these parts is not required. Lubrication however is ~not undesirable and in some cases can improve the efficiency o~ the controlled ;
leakage. The engine preferably achieves an overlap in the effective pres-
sure strokes of the pistons as a result of the size and interrelationship
of the blocking valve and inlet port. The pistons are adapted to rotate
~036S8Z3
through the annular chamber by positive displacement of the working fluid
and with dynamically balancing of the moving elements. Fluid leakage
between the pistons and chamber is controlled to the extent that fluid-tight
seals are not required for sealing the chamber, but at the same time operat-
ing efficiency is maintained over a relatively wide speed range. Tha effect-
iveness of the gas or fluid seals between the pistons and chamber increases
with increased rotor speed.
The rotary engine may be of relatively simple design employing a
relatively small number of parts for which close tolerance, and fluid-tight
seals, are not required so that costs are reduced. The engine has self-
cleaning characteristics to prevent jamming in that any small particles
entrained in the working fluid can easily pass through the operating piston
and valve passageways.
Ihe engine can be operated over a wide range of speeds but yet
maintalns efficiency at low speed operation, can be rapidly reversed in its
direction of rotation, has a low starting friction, and can start at any
rotor angle. The engine can be constructed in a wide range of overall sizes,
in which high operating efficiency is achieved with greater engine size,
and in which a relatively high horsepower-to-weight ratio is obtainable.
From another aspect, the invention provides a rotary engine for
use as a gas engine comprising the combination of a housing formed with a
circular chamber having chamber walls, a rotor mounted for rotation within
the housing, a plurality Oe at least three Oe circumforentially spaced-
apart pistons mounted on the rotor for movement about a circular path within
the chamber, each of said pistons having radially spaced inner and outer ;
surfaces with curvatures conEorming generally to the chamber walls and
being spaced therefrom a clearance distance which permits controlled leakage ;
of gas therebetween, each piston further being formed with a flat end face
which is spaced from the bottom wall of the chamber another clearance distance
which permits controlled leakage of gas therebetween, means forming inlet
and outlet ports in the housing for directing a gas into and from the chamber,
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5823
blocking valve means positioned in the chamber between the inlet and outlet .
ports for blocking gas flow therebetween across the valve while permitting `;
movement of the pistons across the position of the valve, means for rotating ..
the valve in timed relationship with rotation of the rotor and pistons
responsive to gas under pressure being directed into the inlet port, with . .
said pressurized gas imparting at torque force on successive pressure-active ~ ~:
pistons which are exposed to the inlet port within the chamber simultaneous
with leakage of gas through said clearances to create a pressure in the
volume of the chamber on the opposite side of said pressure-active piston :
whereby the pressure differential across the pressure-active piston is
insubstantial so that further leakage past such piston is minimized.
Features of the invention will appear from the following description
in which the preferred embodiment has been set forth in detail in con-
junction with the accompanying drawings.
Brief Description of the Drawings
Figure 1 is an axial section view of a rotary engine incorporating
the invention;
Figure 2 is a cross-sectional view taken along the line 2-2 of
Figure 1 illustrating the elements in one operative position;
Figure 3 is another cross-sectional view similar to Figure 2
illustrating the elements in another operative position;
Figure ~ is another cross-secitonal view similar to Figure 2
illustrating the elements in a further operative position;
Figure S is a partial end velw to a gr~atly
r ~ ;
~ ~ 5
. . ~ ..
1065~3Z3
enlarged scale illustrating the configuration of one of
the pistons shown in Figures 2-4; and
~igure 6 is a partial cross-sectional view of
' another embodiment of the invention which incorporates an
enlarged exhaust port.
ln the drawings Figure 1 illustrates generally
at 10 a rotary engine constructed in accordance with the
invention and which i5 espacially adapted for use as a
motor driven by pressurized gas. When used as a motor the
engine's drive shaft 11 is coupled through a suitable
drive train arrangement, not shown, with the particular
mechanism which is to be operated. Fo,r example, rotary
engine 10 can be coupled wl~h a flow control valve in a ''!''
gas transmission pipeline, with pressurized gas being bled
from the pipeline and supplied to the engine as the work-
ing fluid. As will become apparent from the disclosure
herein, the invention will also find application as a
motor with other working media or fluids, and also as a
; pump in which shaft 11 is powered for pumping a fluid
under pressure.
Rotary engine 10 includes a three-element hous-
ing assembly which comprises a central cylinder block 1~,
a bell cover 13 at one end o~ the block and a mounting
co~er 14 at the other end. The three housing elements are
secured together to ~orm a pressuxe sealed chamber by
means of a plurality of circumferentially spaced elongate
bolts 16 which extend through holes drilled about the
peripheries of the two covers, with threaded nuts 17 being
mounted on the bolt ends.
The outer end face 18 of cylinder block 12 is
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1. ~
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~L~65~;~3
machined to form a circular recess or chamber 19 concen-
tric with the longitudinal axis 21 of the block. The
chamber i9 defined by radially spaced side walls 22, 23
and a bottom wall 24.
Drive shaft 11 is mounted for rotation about
axis 21 by means of sui~able bearings 26, 27 which are
secured within a bore formed through the cylinder block.
When used as a motor the drive shaft is coupled through a
suitable drive train to the desired end use application,
and when used as a pump the drive shaft i5 powered by a
~, suitable prime mover such as an electric motor. The hous-
- ing is pressure sealed around the drive shaft by means ofa ~onical member 25, the inner diameter of which is
grooved to seat O-ring seals 15. A plurality of springs
25a are seated in the rim of member 25 to hold the latter
in close contact with a stationary bushing 30 which is
secured within a circular recess formed in cover 14. The
outer flat end of member 25 thus sealably rotates against
the inner shoulder of the bushing 30. A rotor 28 which
provides a circular piston support member or plate is
mounted on one end of the drive shaft. This rotor also
serves a~ a flywheel for absorbin~ force impulses on the
xotating elements. The inner face 29 of the rotor extends
radially outwardly beyond the outer wall 23 of chamber
19. The clearance between the inner face of the rotor
and the end face 18 oE the block is maintained at an opti-
mum dimension so that movement is frictionless but at the
same time leakage of fluid from the chamber around the
rotor is controlled. The required clearance depends upon
the particular desi~n specifications such as surface
--7--
5~1z3
character and/or .inish..and type of fluid medium employed,
and where engine 10 is utilized as a motor operating from
pressurized gas this clearance preferably, but not neces-
sarily, would be in the range of 0.002" to 0.005".
The spacing between bell cover 18 and rotor 28
- ............. ..defines a chamber 31. The fluid which leaks through the
clearance between the xotor and cylinder block escapes
into this ch~nber so that the contained pressure within
the housing builds up to the point that it approaches the
~ input pressure to the engine. This serves to reduce the
v l~eakage which would otherwi~e occur so-.that enyine effi-
ciency is maintained, and at the same time the clearance
between the block and engine permits relative mover.~cnt .
without frictional contact and without the requ.irement for
sealing members.
Three pistons 32, 33 and 34 are mounted on the
rotor at equally spaced-apart circumferential positions
with each of the pistons projecting into circular chamber
. 19. The circular bases 20 of the piston are seated tight
ly within recesses that are formed about the rotor, and
each piston is secured in position by means o.f a bolt 21
mounted in an open.ing extending through the opposit~ :Eac~
o.f the rotor.
Figure 5 S}10WS the configuration for piston 34
which is typical in construction for the three pistons.
The piston is formed with a generally cylindrical cross
. section of a dic~neter somewhat greatex than the radial
distance between the inner and outer side walls 22, 23 of
chambex 19. The inner and outer surfaces 36, 37 of each
piston are machined with a curvature conforming generally
. -8-
1~J!65~;~3
to the inner and outer chamber walls. The clearances be-
tween the piston surfaces and chamber walls are preferably
maintained within the range ~f 0.002" to 0.005", and this
same clearance is provided between the flat end face 38
of each piston and the 1at bottom wall 24 of the chamber.
The clearance between the piston surfaces and the chamber
walls permits frictionless relative movement, and also
controls leakage of fluid around the pistons in a manner
presently to be described. The inner flank sides of each
piston are also machin~ed with flat, outwardly diverging
surfdces 39, 41.
An inlet port 42 is formed through one side of
tlle housing to direct inlet fluid into communication with
chamber 19, and an outlet port ~3 is formed on the oppo-
site side of the housing to exhaust outlet fluid from the
. chamber. The inlet port is sized and positioned in rela-
- tion to the size and phasing o~ blocking valve 44 so thatpressurized fluid communicates into recess 50 as each
piston sweeps across the inlet, as shown in Figure 4.
This permits pressure to build up behind such piston ba-
fore pressure drops o~ on the leading piston, with the
result that the e~fective pressure stroke, ~or a three-
piston engine, is approximately 130, i.e., 10 ~reater
than the 120 spacing between pistons. In other words
there is substantially at least a-10 overlap of the pres-
sure strokes or the pistons. This precludes engine stal-
li.ng and eliminates deadspots in the engine's operation so
that it can be started at any rotational angle. The inlet
and outlet ports are positioned syl~metrically on either
side of the blocking valve and are designed with the same
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1ai6S~23
flow areas so that the operating characteristics of the
engine are idçntical in either direction of rotation.
Figure 6 shows an embodiment of the invention
for use in unidirectional rotation applications in which
an elongate outlet port 45a and tapped opening 45b are
formed through cylinder block 12'. Outlet port 45a ex-
tends along an arc which is substantially longer in rela-
tion to the diameter of the outlet port of the preceding
embodiment~ Preferably this outlet port extends along an
~ arc of at least one-half, or 6~, of the exhaust stroke,
which,is equal to the 120 arc between adjacent pistons.
This permits outlet gas to exhaust earlier in the exhaust
stroke of each piston whereby backpressure is redu~qd for
improved operating efficiency.
A blocking valve 44 is mounted between the two
ports to block direct fluid communication between the
ports so the fluid is directed in a circular path around
the length of chamber 19. The blocking valve comprises a
semi cylinder 46 having a diameter greater than the radial
width of the chamber. The base of the cylinder is carried
on a shaft 47 which is mounted OII suitable bearings ~8 for
rotation about an axi,s 49 which is parallel with the axis
21 of the drive shaft~ The base of cylinder 46 adjacent
the shaft is circular and is rotatably carried within a
circular seat formed about the housing opening through
which shaft ~7 projects. The opposite end of the cylinder
is machined flat for close-spaced relative movement with
respect to the inner face 29 of the rotor. A concaval
recess 50 is formed in cylinder 46 with a boundary wall
siæed in width sufficiently larger than the outer diameter
. --10--
,
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.. . , . , . . ~ , .... .. .
1065BZ3
of the pistons so as to su~stantially envelope the pistons
as the latter move across the valve location. The portion
of the cylinder on the opposite side of the recess is
formed with a hollow cavity of a sufficient size to dyna-
mically balance the valve for high speed operation.
~ Means is provided to drive blocking valve 44 at
a 3:1 speed ratio, and in counter rotation, with respect
to rotor 28. Preferably this means includes a large dia-
meter gear 52 secured by suitable means such as keying to
drive shaft 11, together with a small diameter gear 53
having one third the number o~ teeth of gear 52 and
secured by suitable means such as keying to shaft 47. The
two gears are in meshing e,.gagement so that the blocking
valve undergoes three revolutions for each revolution of
the rotor. The gearing is arranged such that rotation of
the blocking valve is in precise timed relationship with
movement of successive pistons 32-34 to permit the latter
to move across the valve location without contacting the
blocking va~ve and without losing any appreciable inlet
pressure across the valve.
As portrayed in the step-wise positional illus-
trations of Figures 2-4 it is the cooperation o~ the con-
figuration of valve r~cess ~9 with the con~iguration of
the pistons which permits the pistons to be enveloped by
the valve without contact while at the same time permit-
tiny only a minimum of fluid transfer between the inlet
and outlet ports. Thus, as shown in Figure 3, assuming
that rotor 28 is turning clockwise, the piston has just
entered khe cross-sectional area of rotation of the block-
ing valve with recess 50 turned to accept entry o~ the
.. ~ --11--
~L~6S132~
piston. At the same time leading edge 56 of the recess
has moved close to but out of contact with the leading
surface of the piston.
Continued movement of the rotor carries piston
34 into the twelve o'clock position of Figure 2 at which
' the valve-has rotated with its recess~facing downwardly.
At this position the circular outer surface of the piston
is moving in close-spaced but non-contacting relationship
with the inner circular portlon of the recess. In addi-
~ tion it will be seen that the two recess edges 56, 57 in
this' position are below the,inner wall 22 of chamber 19
for precluding fluid communication between the inle~ and
outlet ports.
Further movement of the rotor carries piston 34
to the exit position of Figure 4. In this position the
inner surface 36 of the piston has cleared the valve loca-
tion and trailing edge 57 of the valve recess is free to
move upwardly in close-spaced but non-contacting relation-
ship with the trailing surface of the piston. Continued
rotation through a complete cycle carries the next two
succeéding pistons'33, 32 through the blocking valve in
a similar manner. It will also be realiz~d that the en-
gine is reversible in operation and that the blocking
valve will envelope the pistons in a similar manner with
counter~clockwise rotor rotation and cl~ockwise valve ro-
tation.
' In operation of the invention, it will be
- assumed that rotary engine lO is to be used as a motor '
' driven from a source of pressurized gas. Inlet port 42 is
connec~ed through suitable conduit means and flow control
-12-
~65~323
. .
valve means, hot shown, with the source of gas. Assuming
that rotor 28 is initially in the position shown in Fig-
ure 3 the gas is directed under pressure through the inlet
port and into the upper righthand portion of chamber 19
where it reacts against piston 32. The force of the gas
acting on this piston imparts a torque to the rotor for
clockwise rotation, and this drives the blocking valve
counter-clockwise by means of the gears 52, 53. The rotor
and pistons have no sliding surfaces and are free to move
frictionlessly within chamber 19. The result is that
~tar_ing friction is very low, lubrication is not required
for these elements, heat generation and wear are low, and
a.l overspeed condition will not char the surfaces as could
occur with existing air motors. At the same time the
close-spaced clearance between the piston and chamber
wall~ controls leakage around piston 32 into the volume 58
behind second piston 33. This trapped volume serves as a
gas seal by forming a backpressure against the pressurized
voiume behind piston 32. The effectiveness of this air
seal increases with increased rotor speeds because there
is less time for gas to leak from the chambers on each
stroke. The close-spaced clearance between the outer
periphery o~ the rotor and ~he housing also controls the
leakage of gas into chamber 31, and the housing, and the
pressure in the chambér and housing builds up to a value
appro~ching the inlet pressure for effectively precluding
further leakage from around the rotor. In addition end
thrust on the bearings is reduced, and therefore bearing
life is increased, as a result of the equalization of
pressure forces in the housing which act on the rotor.
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IOG5823
Continued rotation of the rotor carries the
elements to the serial positions illustxated in Figures
2 and 4 where the blocking valve 44 envelopes the piston
34 in non-contacting relationship Eor permitting it to
pass through the valve location while maintaining fluid
isolation between the inlet and outlet ports. As trailing
piston 34 sweeps by the inlet port pressure builds up to
act on its trailing side while pressure continues to act
against next leading piston 32. This condition exists for
approximately 10 of rotation until trailing piston 34
move~,across the leading edge of the port to the position
of Figure 4, thereby providing an effective pressure
stroke of 130. The press~re of the gases isolated in the
volume 58 between the pistons 32 and 33 serves as a back
pressure to control and limit the degree of fluid leakage
around piston 32. This condition is substantially main-
.. . .
tained until piston 33 registers with outlet port 43 for
exhausting the trapped gas volume 58.
It will be realized that rotary engine 10 per-
20 mits high rotational speeds because the elements, includ-
ing the rotor and blocking valve, are dynamically balanced
and, in addition, the pistons move without Eric~.i.onal COIl-
tact with the walls o~ the circular chamber and blocking
valve. The Erictionless feature results in the engine
having a very low starting torque, in comparison to Eric-
tion contact type engine where starting torques are great~
er than running torques. The engine can also be quickly
reversed in directional rotation, even whi.le operating at
high speed,, by directing the inlet gas into port 43 with
port 42 acting as the exhaust. This reversibility feature
l~GSS Z3
is important in applications of the invention which in-
volve differential response, e.g., for differential valve
closing. The operating characteristics of the engine are
identical in either direction of rotation.
While being capable of running at high speed in
the manner of a turbine, engine 10 may also be operated
throughout a full speed range while maintaining operating
efficiency. Thus, good efficiency is obtained at low
speeds in the manner of a positive displacement engine as
a result of controlling the leakage from around the pis-
tons. At hlgher rotational speeds efficiency increases as
a result of the`reduced le~kage factor. Operating effi-
ciency is also increased where the engine is scaled up-
wardly in size while main~aining substantially the same
clearance dimensions because the ratio of the piston
dimensions to leakage gap becomes greater. In addition
the larger size engines of the inventio~ can run at high
speeds because of the low friction, dynamically balanced
features so that a much higher power can be achieved. For
~0 example, doubling the scale of the motor increases the
power by a factor of eight.
Rotary engine 10 may be relatively inexpensively
con~txucted as a result o`f eliminatin~ the requirement for
maintaining close ~olerances between the piston, chamber
and valve elements. Because sliding surfaces are not
employed, the ~urface finish is not limited to any par-
ticular finish. In addition, the engine elements may be
fabricated from materials selected for their compatibility
with the working medium. For example, stainless steel
could be used where the working medium is a noxious gas,
, .
- -15-
~ ;S8~3
or a ceramic material could be used for high temperature
gases. The inventlon ~acilitates the use of materials,
which would otherwise be infeas~ble in conventional rotary
engines, such as refactory materialsp as a result of the
finite clearance between the moving elements as well as
gas sealing due to the backpressure effect. These fea-
tures also result in permitting the engine to be scaled
much larger than friction contact type engines and conven-
tional turbine engines.
The provision of maintaining a controlled clear-
ance between the piston, valve and chamber walls prevents
the binding or jamming which could otherwise occur with
c:!ose tolerances, especially where small foreign particles
may become between the elements, or where the elements may
change dimension due to wear or temperature variations.
The engine has a self-cleaning effect due to the relative-
ly open operating passages because small foreign particles
which could otherwise lodge between the elements are
ca/rried throuyh by the mainstream fluid flow. ~urther-
more, no lubrication i.s required between the pistons,
valve and chamber walls because o~ the elimination of
close tolerances and sliding sur~accs~
The ro~ary engine oE the invention will find
application as a motor design over a wide power size range
from fractional horsepower up to large power station size
with substantially the same design configuration. Be-
cause of the relatively few number of small parts the
engine achieves a relatively low horsepower-to-weight
ratio.
In the engine of the present invention driving
-16-
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lOGSB%3
torque is applied to the pistons without any substantial
gas expansion effect of the type that would occur in ex-
panding chamber type engines. This means that the engine
operates with substantially continuous full force on the
pistons without pressure surges.
The volumetric fuel consumption of this engine
is largely a function of speed and inlet pressure and is
relatively independent of power. This is in comparison to
conventional air motors in which pressure is lost in work-
ing against the on-coming vanes moving through the cham-
b~r~.
The invention also can be advantageously adapted
a~ a compound engine wherein the exhaust from one con-
~rolled leakage rotary engine is directed into the inlet
of a second similar engine for increasing the overall
, efficiency. In addition, operating borque variations can
be reduced by coupling two or more of the rotary engines
for out-of--phase operation on a common drive shaft.
While the foregoing embodiments are at present
considered to be preferred it is understood that numerous
variations and modifications may be made therein b~ those
skilled in the a~t and it is intended to cover in the
append~d claims all such variations and modi~ications as
~all within the true spirit and scope of the invention.
-17 !,
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