Internal combustion engine with rankine bottoming cycle

A barrel-type internal combustion engine 1 has double-ended pistons 10 reciprocally movable within cylinders 2 disposed in a ring about a central axis 3. The pistons 10 are interconnected with a central drive member 16, by means of a cam 17 carried by the drive member 16, whereby reciprocatory movement of the pistons causes the drive member to rotate. A closed circuit pressurized vapor system which makes use of waste engine heat, includes an expander 110, enabling mechanical energy obtained from expansion to be applied to the rotary member 16, to augment the power generated by the pistons 10. The expander 110 is formed by a hollow interior 31 in the rotary member 16, which houses a shaft 37, the shaft 37 defining with the member 16 an annular chamber 42. The rotary member 16 and shaft 37 rotate eccentrically relative to each other and in the same direction. Sealing components 32, 35 cooperate so as to divide the chamber 42 into relatively high and low pressurized vapor zones as the drive member 16 and shaft 37 rotate eccentrically.

BACKGROUND TO THE INVENTION 
This invention relates to engines. 
The invention is primarily concerned with internal combustion engines. 
However, it will be clear from the present disclosures that the internal 
combustion engine described and illustrated herein may be adapted for use 
as a compressor. Accordingly, as used herein, the term "engine" is not 
necessarily confined to internal combustion engines and may, on occasions, 
include compressors. 
SUMMARIES OF THE INVENTION 
According to one aspect of the invention, an internal combustion engine has 
at least one piston reciprocally movable within a cylinder, and provided 
with means for causing the piston to dwell at one end of its stroke. The 
piston may be caused to dwell at both ends of its stroke, where the 
periods of dwell may be equal or non-equal. 
According to another aspect of the invention, an internal combustion engine 
comprises a stationary cylinder, a piston reciprocally movable within the 
cylinder, and means for introducing a metered supply of combustible fluid 
into the cylinder, so that combustion can take place, said means 
comprising a fuel-supply member movable relative to the cylinder and in a 
plane disposed substantially normal to the path of piston movement, 
whereby the combustible fluid is introduced into the cylinder in a 
controlled manner as the member traverses said cylinder. 
The piston may comprise a double-acting piston, and two such movable 
members may then be provided, one at each end of the cylinder. 
According to yet another aspect of the invention, an internal combustion 
engine comprises at least one piston reciprocally movable within a 
cylinder and interconnected with a rotary member of hollow form by cam 
means carried by the rotary member, whereby reciprocatory movement of the 
piston causes rotation of the rotary member, and auxiliary means for 
augmenting rotation of the rotary member, said auxiliary means comprising 
a closed circuit pressurised vapour system including an expander disposed 
within the hollow rotary member and interconnected therewith, whereby 
mechanical energy obtained from expansion of the vapour in the expander is 
applied to the rotary member. 
The interior of the hollow rotary member preferably comprises part of the 
vapour expander. 
The hollow rotary member may house a shaft which defines with the rotary 
member a chamber of annular form, means whereby the hollow rotary member 
and the shaft disposed therein rotate eccentrically relative to each other 
about substantially parallel axes, and in the same direction, and sealing 
means cooperating with the rotary member and the shaft so as to divide the 
chamber into relatively high and low pressure zones as the rotary member 
and the shaft rotate eccentrically. 
According to a further aspect of the invention, a compressor form of the 
engine comprises a stationary cylinder, a piston reciprocally movable 
within the cylinder, and air control means for controlling a flow of air 
to be compressed into one end of the cylinder, said means comprising a 
member, movable in a plane disposed substantially normal to the path of 
piston movement, and having a port which, when aligned with said cylinder 
end, allows air to flow through the port and into the cylinder. The piston 
may comprise a double-acting piston and two such ported members may be 
provided, one at each end of the cylinder. The piston may be 
interconnected with a rotary member by cam means carried by the rotary 
member, whereby rotation of the rotary member causes the piston to 
reciprocate, the ported members being carried by the rotary member, so as 
to rotate therewith.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference first to FIGS. 1 to 10, particularly FIG. 1, an internal 
combustion engine 1 of the compression-ignition type, is illustrated 
thereby. 
The engine 1 is a 2-cycle engine, operating on a constant volume, heat 
addition cycle. The engine 1 also includes means whereby Rankine bottoming 
compound cycle operation takes place. 
As used herein, "constant volume, heat addition" means that a substantial 
amount of heat is released to the combustion air whilst that air is held 
at substantially constant volume. 
The engine 1 is also of the barrel type, provided with twelve equi-spaced 
cylinders 2 disposed in a circle, around a central, longitudinal, axis 3. 
The longitudinal axes of the cylinders 2 are substantially parallel to the 
axis 3. 
The engine body, or block 4, is formed in two sections, namely 4a and 4b, 
demountably secured together by nut 5 and bolt 6 assemblies as best seen 
in FIG. 4. The bolts 6 are secured in body section 4a and extend through 
holes 7 formed in body section 4b. Upper and lower rings of exhaust ports 
8 are formed in the body sections 4a and 4b. 
The cylinders 2 are formed in the body 4; six cylinders in each body 
section. Each cylinder 2 locates a piston 10 movble within the cylinder in 
a reciprocatory manner. The pistons 10 are double-ended; a combustion 
space 11 being formed in each end. As best seen in FIG. 4, the combustion 
spaces 11, which are of elongated form in plan view, i.e. when viewed 
along the path of piston movement, are also arcuate; the common centre of 
the arcs being disposed on the central axis 3 of the engine 1. The pistons 
10 are provided with piston rings 12. 
The engine 1 has a central power output shaft 15, the longitudinal axis of 
which is common with axis 3. The shaft 15 is an integral extension of a 
rotary drive member 16 of hollow form, best illustrated by FIG. 8. 
The rotary member 16 carries an actuating cam 17, disposed between upper 
and lower cylinder cover plates 18. The rotary member 16 is rotatable 
within the engine body 4; labyrinth seals are provided by circumferential 
slots 19, 20 formed in the body 4 and covers 18 respectively. Further 
labyrinth seals are provided by circumferential slots 21, 22 formed in the 
body 4 and rotary member 16 respectively. Radially disposed seals 23 
(FIGS. 2 and 3) are also provided at opposite ends of the cylinders 2. The 
arrangement is such that the cylinder cover plates 18 rotate in planes 
disposed substantially normal to the paths of piston 10 movement. 
Each piston 10 is formed with a central, cut-away portion 25 within which 
is disposed a pair of axially-spaced rollers 26. The rollers 26 of all the 
pistons 10 bear on the upper and lower surfaces of the cam 17 so that as 
the pistons 10 reciprocate within their cylinders 2, the cam 17 and hence 
the rotary member 16 is made to rotate, in order to produce torque at the 
drive shaft 15. 
The cam 17 has a particular profile, described hereinafter, which causes 
each piston 10 to dwell at opposite ends of its stroke. The dwell is 
substantially equal at both ends of the stroke. The period of dwell is 
between 10.degree. and 20.degree. of rotary member 16 rotation. 
An annular channel 30 is formed in the rotary member 16. The channel 30 
extends around, and is radially spaced from, a central, blind-ended recess 
31 of circular cross-section, when viewed in plan. The recess 31 and 
channel 30 are divided from each other by a sleeve 29 co-axial (and 
integral) with the rotary member 16. (See also FIG. 18). A rib or vane 32 
extends radially inwards, from the wall of the sleeve 29, and also extends 
longitudinally downwards, for the full depth of the recess 31. A slot 33 
is formed in the wall of the sleeve 29, immediately adjacent the vane 32. 
The slot 33 extends longitudinally alongside the vane 32 and serves as a 
port providing communication between the recess 31 and channel 30. 
The vane 32 extends into a cooperating slot 34 formed in a rod-like seal 
member 35, which is located, so as to rotate relative thereto, by a slot 
36 (FIG. 4) formed in an intermediate shaft 37 which is disposed within 
the hollow rotary member 16. The shaft 37 has a central, axial, bore 38 
which locates a central or inner shaft 39. A longitudinal slot 40 formed 
in the shaft 37 forms a port allowing communication between the bore 38 
and the recess 31. The lower end of the inner shaft 39 is supported by the 
rotary member 16, through a bearing 41. The intermediate shaft 37 and the 
sleeve 29 together define an annular chamber 42 (FIGS. 12 to 15). It will 
be appreciated that, as used herein, the term "annular" is not to be 
construed in a strict geometrical sense, as the width of the annular 
chamber 42 is not uniform. 
The interfitting elongate vane 32 and associated elongate seal member 35 
carried by shaft 37 together form sealing means cooperating with the 
rotary member 16 and shaft 37 to divide the chamber 42 into relatively 
high and low pressure zones, as described more fully hereinafter. 
The longitudinal axis of the inner shaft 39 is shown at 45. The 
interfitting vane 32 and seal member 35 extend substantially parallel to 
the axis 45 and rotate thereabout. The upper end of the inner shaft 39 
carries a cover plate 46. The inner shaft 39 is stationary. Intermediate 
shaft 37 is rotatable about the inner shaft 39, and is driven by the 
rotary member 16, through the interfitting vane 32 and seal member 35. The 
axes 3 and 45 are off-set and substantially parallel to each other. As the 
axis 45 is also the longitudinal axis of the intermediate shaft 37, the 
shaft 37 is rotatable eccentrically relative to the rotary member 16. 
A hollow 50 is formed within the inner shaft 39. An axial slot 51 is formed 
in the "wall" defined by the hollow 50 and the outer surface of the inner 
shaft 39. 
The outer surface of the intermediate shaft 37 carries radially extending 
strips 52 (see FIG. 4) located in slots formed in said outer surface. The 
strips 52, which are free to move radially, within their locating slots, 
are provided so as to form gas seals between adjacent parts of the 
intermediate shaft 37 and the wall of the recess 31, as the intermediate 
shaft 37 rotates. 
The cover plate 46 is provided with holes 60 (FIG. 7) alignable with 
screw-threaded holes 61 (FIGS. 2 and 3) whereby the cover plate 46 can be 
demountably secured to the engine body 4, using bolts. (Not shown). 
Arcuate slots 62, 63 formed in the cover plate 46 provide, respectively, 
air inlet and vapour outlet openings. The vapour outlet openings 63 
provide communication with the annular channel 30 formed in the rotary 
member 16. 
The upper and lower cylinder cover plates 18 each carry a pair of fuel 
injectors 65, (FIG. 1), disposed in screw-threaded holes 66. (FIGS. 5 and 
8). It will be noted that only the fuel injectors 65 of the upper cover 18 
are shown in the drawings. The cover plates 18 thus serve as fuel-supply 
members. 
A metered supply of liquid fuel is fed to all four injectors 65 
simultaneously by a fuel pump 67 (FIG. 5) comprising a piston 68 
reciprocable in a cylinder space 69 formed in the lower cylinder cover 
plate 18 and operable by a cam 70, which bears on a roller 71 carried by 
the piston 68. 
The cam 70 is stationary, and is carried on the upper face of a lower cover 
plate 75. (FIG. 9). The cover plate 75 is releasably secured to the engine 
body 4, using bolts, in the same way as cover plate 46 is held in place, 
holes 76 being formed in the cover plate 75 for this purpose. A central 
hole 77 is formed in the cover plate 75 to allow free rotation of the 
drive shaft 15 therein. 
Pairs of arcuate ports formed in the periphery of the lower cover plate 75 
connect with arcuate slots formed in the upper surface of that plate so as 
to provide air inlet openings 80. The openings 80 are alignable with air 
induction ports 81 (FIG. 1) formed in the lower cylinder cover plate 18. 
The ports 81, (similar ports 81 (FIG. 8) are formed in the upper cylinder 
cover plate 18) are shaped to impart swirl to air flowing through the 
ports 81. 
Fuel is supplied to the injection pump 67 by way of a radially-disposed 
passageway 85 (FIG. 9) formed in the lower cover plate 75. A metered 
supply of fuel passes from the pump 67 to the fuel injectors 65 by way of 
internal passageways, (not shown), formed in the rotary member 16. 
The lower cover plate 75 houses a feed pump 90 comprising a piston 91 
reciprocable in a cylinder space 92. The piston 91 carries a roller 93 
which bears against a cam 94 carried by the drive shaft 15, so as to 
rotate therewith. Non-return inlet (95) and outlet (96) valves (FIG. 1) 
control flow of fluid to and from the cylinder space 92. The drive shaft 
15 is located by a hole 97 formed in the cam 94. 
The drive shaft 15 also carries the rotor 100 of a starter-motor 
alternator. (FIGS. 1 and 10). The stator (101) of the alternator is 
secured at its periphery to the lower cover plate 75 and is provided with 
a central hole 102 to allow free rotation of the drive shaft 15 therein. A 
central hole 103 formed in the rotor 100 locates the drive shaft 15. 
With reference now to FIGS. 17 and 18, the engine 1 is provided with a 
Rankine Bottoming Compound Cycle Operation System. (The intermediate shaft 
37 has been omitted from FIG. 18 for clarity). The cycle enables heat 
energy present in the engine exhaust gases issuing from the outlet ports 8 
(FIG. 1) to be transferred, as mechanical energy, to the rotary member 16. 
The system, which in this example employs "FREON" (Registered Trade Mark) 
as the working fluid, makes use of the feed pump 90, to convey the fluid 
when in liquid form, an expander, generally indicated by reference numeral 
110 and illustrated more particularly in FIGS. 12 to 15, a condenser 111, 
a regenerator 112, and a vapour generator 113. An annular manifold 114 
(FIG. 18) collects exhaust gases issuing from the rings of upper and lower 
exhaust ports 8. A fan unit 115 is used to blow air over the heat-exchange 
surfaces of the condenser 111, as indicated by arrows 116. The fan 115 is 
driven by the engine 1, by way of a shaft 117. 
OPERATION OF THE ENGINE 
For simplicity the following description is confined to a single 
piston/cylinder assembly. With first reference to FIG. 11, at stage A, 
combustion of the air/fuel mixture has been completed and the piston 10 is 
about to commence its downward, i.e. expansion stroke. The piston 10 is 
thus at top dead centre. (T.D.C.). 
At stage B, expansion has been completed. Continued downward motion of the 
piston 10 results in the associated exhaust port 8 being uncovered. 
At stage C, the piston 10 continues to move downwards. Most of the exhaust 
port 8 has now been uncovered, and high velocity exhaust gases escaping 
through the exhaust port create a depression in the cylinder 2. (The 
Kadency effect). 
As mentioned above, reciprocating movement of all twelve pistons 10 cause 
the rotary member 16 to resolve, by applying rotary forces to the cam 17. 
As the rotary member 16 revolves, the unitary upper cylinder cover plate 18 
is rotated correspondingly, in the same direction, at the same speed and 
about a common axis 3. This rotation causes the air inlet port 81 in the 
plate 18, to begin to expose the top of the cylinder 2 and thus admit 
combustion air thereto. The cylinder cover plates 18 thus form rotary 
"shutters". 
At stage D, the piston 10 has reached bottom dead centre. (B.D.C.). Exhaust 
gases continue to flow out of the cylinder 2 by way of the exhaust port 8, 
drawing fresh air through the air inlet port 81, which has now uncovered a 
larger portion of the a upper end of the cylinder 2. The piston 10 remains 
at B.D.C. for substantial period with the exhaust port 8 fully open while 
scavenging of the exhaust gases takes place. The delay, or dwell, is of 
the order of 15.degree. of driveshaft 15 rotation. 
At stage E, the piston 10 has completed its delay period and begins to move 
upwards. The air inlet port 81 is now fully open and the top of the 
cylinder 2 is fully exposed to inflowing air. The exhaust port 8 is still 
open. 
At stage F, the piston 10 continues its upward stroke. The exhaust port 8 
has been closed by piston movement but the air inlet port 81 has not yet 
moved away from the top of the cylinder 2. 
At stage G, the rotary cylinder cover plate 18 has now completely covered 
the top of the cylinder 2. The continuing upward movement of the piston 10 
begins to compress air trapped in the cylinder 2. 
At stage H, the piston 10 is at T.D.C. Air trapped within the cylinder 2 is 
compressed to the volume of the combustion chamber 11. (FIG. 1). Another 
substantial delay, again of the order of 15.degree. of driveshaft 
rotation, occurs. 
The injector 65, which rotates with the cylinder cover plate 18, now begins 
to inject a metered supply of fuel into the volume of compressed air, as 
the injector traverses the combustion chamber 11. Injection continues 
during passage of the injector 65 over the combustion chamber 11. 
At stage I, the piston 10 has completed its delay period at T.D.C. 
Combustion of the air/fuel mixture has taken place, at constant volume, 
and to a substantial degree. The piston 10 is about to commence its 
downward, power-generating stroke. 
It will be appreciated that the cycle of operation of each cylinder/piston, 
and at each end of each piston 10, is as described above. The pistons 10 
in adjacent cylinders 2 reach T.D.C. in succession as the cam 17 rotates; 
when a piston 10 is at T.D.C. as regards one end of the cylinder 2, it is 
at B.D.C. as regards the opposite end of the cylinder 2. It will be 
understood that the motion of each piston 10 is governed by the profile of 
the cam 17, which as shown in FIG. 8 is shaped so that each piston 10 
undergoes two oscillations for each complete revolution of the cam 17, and 
so that the dwell period is about 15.degree. (0.52 rad) of cam 17 rotation 
both at T.D.C. and at B.D.C. 
The displacement "S" of a piston is shown in FIG. 16 in relation to the 
angle of rotation ".phi." of the cam, in the case where the dwell period 
is ".alpha." at T.D.C. and B.D.C. The piston displacement "S"is given by 
the equation: 
EQU S=(d/2)[1-Cos .omega.] 1 
where 
.alpha.=piston stroke 
.lambda.=the number of oscillations of the piston in one revolution of the 
cam (i.e. the number of lobes on the cam) 
##EQU1## 
The more general case where the dwell period is not the same at each end of 
the piston stroke is represented graphically in FIG. 19. The above 
equation 1 may again be used to describe the piston displacement, with the 
following values of ".omega.": 
##EQU2## 
where .alpha.=dwell period (radians) at one end of the piston stroke 
.beta.=dwell period (radians) at the other end of the piston stroke 
##EQU3## 
It will be appreciated that if desired the shape of the cam 17 could be 
changed so as to provide non-equal dwells at opposite ends of the 
cylinders. 
The invention provides an engine with the following advantages: 
(1) Causing substantial dwell of the pistons 10 at T.D.C. while combustion 
of air/fuel mixture is taking place, enables the engine 1 to operate on a 
constant volume heat addition cycle. This cycle is more efficient than the 
thermodynamic cycle of conventional engines, which only approximate to the 
constant volume heat addition cycle. 
(2) Delaying the pistons 10 substantially at B.D.C., during which period 
exhaust ports 8 remain fully open, results in efficient scavenging of the 
exhaust gases out of the cylinders 2. 
(3) Since the pistons 10 are delayed at B.D.C. at maximum exhaust ports (8) 
area, the exhaust port height is reduced. This allows a substantially 
complete expansion of the gas in the cylinder which imparts extra effort 
to the drive shaft 15. Since the flow of exhaust gases out of the cylinder 
requires a finite time, conventional engines uncover the exhaust ports too 
early, resulting in incomplete expansion of gases in the cylinders and 
therefore reduction in power output, with an increase in specific fuel 
consumption. 
As mentioned above, the engine 1 operates as a constant volume, heat 
addition cycle. That is, a thermodynamic cycle in which a substantial 
amount of heat is added to the combustion air whilst that air is held at 
substantially at constant volume. Conventional engines approximate the 
constant volume heat addition cycle and employ a piston kinetically 
connected to a crankshaft in such a way that the volume of burning gas 
changes during combustion. In the case of the present invention, the 
volume of the compressed air stays substantially constant during 
combustion. This results from piston dwell. 
Use of the invention is not confined to compression-ignition engines. 
Engine 1 may alternatively be provided with ignitors and used as a 
spark-ignition engine. In this case the arcuate combustion chamber 11 of a 
piston 10 is best replaced by a hemi-spherical form of combustion chamber 
formed in the piston top. Fuel injection is then caused to take place when 
the modified piston 10 travels between stages G and H (FIG. 11). As the 
piston 10 reaches T.D.C., the associated ignitor will have reached the 
centre of the hemi-spherical combustion chamber 11. A spark is then 
generated which ignites the air/fuel mixture. 
In the case of the present embodiment, the ends of the pistons 10 have 
minimal clearance with the inner surfaces of the cylinder heads 18, 
combustion taking place within the chambers 11 formed within the pistons. 
In a modification, the piston/cylinder head 10/18 clearances are increased 
and the volumes of the combustion chambers 11 reduced (to nil if 
necessary) to provide combustion spaces. 
Since the pistons 10 are delayed at T.D.C. and B.D.C. for sufficient time 
to allow combustion to procede, the ignition advance mechanisms of 
conventional spark-ignition engines are not needed. This means a simple, 
reliable and cheap spark-ignition system, since the electronic transducers 
and microprocessors needed for modern engines of this type, in order to 
determine the desired ignition advance curve, are no longer needed. 
A suitable form of spark-ignition system, using the rotary member 16 as a 
distributor, can be provided. 
Such a system may comprise an insulated ring of pick-up pegs (not shown) 
disposed around the drive shaft 15. Insulated leads disposed within the 
rotary member 16 are used to carry the high voltage current to the 
spark-ignitors. 
The pegs mounted on the drive shaft 15 cooperate with stationary magnets 
(not shown) whereby a trigger system as used in conventional electronic 
ignition devices is formed. 
The rotary cylinder cover plates 18 provide means for admitting fresh air 
and fuel into each cylinder and igniting the resulting air-fuel mixture. 
The admission of air, the injection of fuel, and in the case of a 
spark-ignition version of the engine 1, ignitor, take place in cyclic 
order, i.e. the induction ports 81 on the cylinder cover plate 18 admit 
air to each cylinder 2 in turn. Similarly the fuel injectors 65 operate 
with respect to each cylinder 2 in turn. The induction ports 81, injectors 
65 and, in the case of a spark-ignition version of the engine, the 
ignitor, on each rotary cylinder cover plate 18 are independent of the 
number of cylinders 2. That is to say, an injector and an induction port 
are not required for each cylinder. 
The rotary cylinder cover plates 18 provide the engine with an elegant 
solution to a complex problem in engine design, namely the induction of 
fresh air into the cylinders. 
The rotary cylinder cover plates 18 may be provided with means for 
accelerating the flow of air through the induction ports 81. For example, 
flow-accelerating blades or vanes disposed in the ports 81. 
The engine 1 avoids the need for a camshaft, as well as tappets and valves 
for each cylinder, as in conventional engines. The number of induction 
ports 81 formed in each rotary cylinder cover plate 18 is independent of 
the number of cylinders 2. This results in a more simple, reliable and 
cheap induction system. Each cylinder 2 achieves the same volumetric 
efficiency as the others, as fresh air is admitted to each cylinder on 
exactly the same conditions, Furthermore, a high volumetric efficiency can 
be achieved due to the unrestricted flow of air into the cylinders 2 and 
to the large induction port area which exposes the whole of a cylinder to 
incoming air. Rotation of the induction ports 81 as the associated cover 
plate 18 rotates, results in supercharging of the cylinders 2. A high 
volumetric efficiency results as the induction process occurs in a short 
period of time. Most of the incoming air does not ome into contact with 
the hot cylinder walls, and there is also no tendency for mixing of the 
exhaust gases and the incoming air. 
Since all the injectors 65 operate simultaneously, each cylinder 2 receives 
precisely the same amount of fuel. The resulting symmetrical distribution 
of combustion forces as sequential combustion takes place results in a 
well balanced engine. Since the fuel is injected into each cylinder 2 
while the associated injector 65 traverses the top of that cylinder, there 
is excellent mixing between the atomized fuel droplets and the air trapped 
with the cylinder 2. This results in efficient combustion. 
By providing each piston 10 with a hemispherical combustion chamber, an 
even higher combustion efficiency should be achieved. 
The rotary member 16, with the two rotary cylinder cover plates 18 at 
opposed ends is a self-equilibriating unit. This means that the stress 
path within the member 16 balances out the forces applied thereto, whereby 
substantially no significant forces are transmitted to the engine body 4. 
This results in a significant reduction in the stress levels to an engine 
body 4, making it possible to construct the engine body 4 out of materials 
such as ceramics which cannot be expected to withstand high stresses, 
particularly in tension, but nevertheless possess a number of desirable 
properties such as low weight, high operating temperatures and thermal 
insulation capabilities. This makes the concept of an Adiabatic engine 
feasible. In such an engine the rotary cylinder cover plates 18 can easily 
be thermally insulated by two semi-circular ceramic plates on each cover 
plate 18. The rotary member 16, which itself experiences much higher 
stresses than the engine body 4, can be constructed out of a single piece 
of high strength material to withstand these stresses. For example, forged 
steel machined to final tolerances. The engine 1 is substantially free 
from vibration, is aerodymanically clean and has only a small frontal 
area. Thus advantage can be taken of its low stress level body to change 
ways of constructing aircraft structures. Hitherto, an airframe has been 
built to support an engine. Now an engine can become part of the load 
bearing structure. 
The rotary cylinder head arrangement provided by the cover plates 18 also 
enables the construction, assembly and maintenance of the engine 1 to be 
greatly simplified. This is because the engine body 4 can be split 
longitudinally in two halves as shown In FIGS. 2 and 3. From the 
construction point of view, higher tolerances of piston 10 clearance can 
be achieved since the bores of cylinders 2 can be drilled right through 
from one end, resulting in fewer construction operations and therefore 
lower costs. 
Furthermore, the engine 1 comprises a small number of identical components. 
It will be appreciated also that the engine can be scaled up in size and/or 
horsepower without any significant increase in comlexity. 
With reference now to FIGS. 12 to 15, which illustrate an expander 110 
formed within the hollow rotary member 16, and intermediate therewith, the 
member 16 forming part of the expander, it will be appreciated that the 
rotary member 16 and the intermediate shaft member 37 rotate 
simultaneously in the same direction, (arrow 125) but not about the same 
centre. It will also be appreciated that the vane 32 and the cooperating 
seal member 35 together form gas seal means which divide the annular 
chamber 42 into two zones, referred to below. 
The rotary member 16 rotates about the axis 3, whereas the intermediate 
shaft member 37 rotates about the axis 45. As a result of this kinematic 
arrangement, the intermediate shaft 37 rotates slightly out of phase with 
respect to the rotary member 16. Thus as the member 16 rotates with 
constant angular velocity, the angular velocity of the intermediate shaft 
37 varies slightly around (.+-.) the constant angular velocity of the 
member 16. The slight discrepancy in the angular velocities of the member 
16 and the intermediate shaft 37 is accommodated by a small angular 
rotation of the cylindrical seal 35 about its own geometric centre, as the 
vane 32 moves (relatively) in and out of the cylindrical seal 35 at the 
same time. Each of the radial seals 52 carried by the shaft member 37 
comes into contact with the adjacent inner surface of the rotary member 16 
.+-.30.degree. from the line of eccentricity and moves only a small 
distance in and out of its locating slot in the intermediate shaft 37 
during the period of contact. That portion of the chamber 42 to the left 
of the vane 32 (as viewed in FIG. 12) progressively increases with 
rotation of the member 16 whereby expansion of the high pressure vapour 
occurs. That portion of the chamber 42 to the right of the vane 32 (as 
viewed in FIG. 12) progressively decreases, expelling the low pressure 
vapour left from the previous revolution, towards slot 33 and thus into 
the exhaust collector channel 30. The two portions of the chamber 42 
comprise high and low pressure zones which are seperated by the vane 32 
and cooperating seal member 35. The central shaft 39, which remains 
stationary, serves two purposes. Firstly, it locates the intermediate 
shaft 37. Secondly, it acts as a "rotary" valve by admitting high pressure 
vapour into the expansion chamber 42 formed between the intermediate shaft 
37 and rotary member 16. 
As shown in FIG. 12, the slot 40 in the intermediate shaft member 37 begins 
to traverse the slot 51 in the central shaft 39. This allows an outward 
flow of high pressure vapour to take place from the hollow 50 of the shaft 
39 towards the expansion volume or high pressure zone on the left hand 
side of the vane 32. The volume on the right hand side of the vane 32 
comprises the low pressure zone as it contains low pressure vapour from 
the expansion process which took place during the previous revolution of 
the shaft member 37. 
In FIG. 13, the slot 40 has completely traversed the slot 51 and the flow 
of vapour into the high pressure zone of the chamber 42, i.e. to the left 
of the vane 32, is complete. Between the stages illustrated by FIGS. 12 
and 13, the outward flow of high pressure vapour causes a constant 
pressure expansion, creating torque applied, by way of vane 32, to the 
rotary member 16. 
Between the stages, illustrated by FIGS. 13 and 14, the vapour trapped in 
that portion of the chamber 42 on the left hand side of the vane 32 
undergoes a polytropic expansion, continuing to apply torque onto the 
member 16. At the stage illustrated by FIG. 14, both the polytropic 
expansion and the expulsion of the low pressure vapour from the previous 
revolution have been completed. 
With reference to FIG. 15, the vane 32 has traversed the line of 
eccentricity. Expulsion of the low pressure vapour is about to take place 
through the slot 33. Further rotation of the vane 32 causes a high 
pressure zone to be formed on the left hand side of the vane 32. Vapour 
then expands, at constant high pressure, when slots 40 and 51 again come 
into register with each other. 
The vapour cycle illustrated by FIGS. 12 to 15 utilizes the heat energy 
present in the engine exhaust gases, converts this heat energy into 
mechanical energy through the expander 110, and applies this mechanical 
energy to the rotary member 16. Thus the extra power gained by the 
expander 110 is transferred to the rotary member 16. The engine 1 is 
therefore provided with auxiliary means for augmenting rotatin of the 
rotary member 16. 
With reference to FIGS. 17 and 18, the engine exhaust gases pass from the 
exhaust collecting manifold 114, and then through the vapour generator 113 
to the atmosphere, transferring heat energy to the working fluid (FREON), 
which flows through the vapour generator 113 in counterflow. The high 
pressure vapour leaving the vapour generator 113 is then expanded through 
the expander 110 of FIGS. 12 to 15 in order to create extra torque on the 
shaft 15. Low pressure vapor flows from the expander 110 to the 
regenerator 112 to the condenser 111. In the regenerator 112, heat from 
the low pressure vapour is reversibly transferred to the condensed fluid 
which is pumped by the feed pump 90, back to the vapour generator 113. The 
cycle is then repeated. 
The cylindrical shape of the engine 1 allows the various components of the 
Rankine bottoming cycle to be made compact. (A bottoming cycle is a 
thermodynamic cycle which utilises heat energy in the exhaust stream as a 
heat source). Thus the vapour generator surrounds the engine 1, and the 
space within the hollow rotary member 16 is utilized to house the vapour 
expander 110. 
Forming the vapour generator 113 so that it surrounds the exhaust gas 
outlet ports 8 makes it possible to extract the maximum heat capacity out 
of the exhaust gases. As the gases do not have far to travel before 
entering the vapour generator 113, they retain their high temperature. The 
vapour generator 113, by surrounding the engine 1, not only acts as a 
muffler but also as an effective noise suppressor as well. It also serves 
to utilize the pressure waves issuing from the exhaust ports 8, so as to 
prolong initial depressions caused by the Kadency effect, referred to 
above. 
By constructing the vapour expander 110 so as to take advantage of rotary 
movement of the member 16, an ideal coupling of the primary and secondary 
thermodynamic cycles is achieved with only a small number of components. 
No gearbox is needed to transfer the work of the expander 110 to the 
rotary member 16, so higher efficiency and reliability can therefore be 
achieved than if a gearbox had been used. 
The expander 110 of the engine 1 could be used as a starter motor, by using 
a compressed air supply. 
The engine 1 may be modified for use as a compressor. In this mode, the 
engine 1 is devoid of such unwanted features as exhaust ports 8, fuel 
injectors 65 and expander 110, and the rotary member 16 may be used as the 
rotor of an electric motor. 
The air ports 81 will need to be doubled--one set to allow atmospheric air 
to enter and the other in the place of the fuel injectors 65 to allow 
compressed air to be discharged. 
Movement of the pistons 10 need not be confined to paths substantially 
parallel to the central axis 3. In a (non-illustrated) modification, the 
cylinders 2 may be disposed so that they extend radially outwards from the 
axis 3. The piston actuating cam may then comprise an annular member, the 
central axis of which coincides with the axis 3. 
The engine 1 is expected to provide high torque at low R.P.M., allowing it 
to drive, for example, a propeller or propeller-fan without the need for a 
gearbox. 
Calculations indicate that the engine 1 should be able to burn 
substantially less fuel than conventional turboshaft engines. The 
estimated high fuel efficiency of the engine 1 is attributed to the 
following factors: 
1. Low frictional loses within the engine itself. 
2. Delay of the pistons (10) at TDC while combustion is taking place, 
allowing operation of the engine on a constant volume, heat addition 
cycle. 
3. Delay of the pistons (10) at BDC while the exhaust ports 8 are fully 
uncovered. 
4. Higher combustion efficiency of the air-fuel mixture, due to good mixing 
of atomized fuel droplets and air as the fuel injectors 65 traverse the 
arcuate combustion chambers 11. 
5. Selective actuation of the fuel injectors 65, enabling fuel to be 
delivered to particular cylinders 2. The engine output power can therefore 
be digitized and its part-load efficiency increased. By selectively 
switching off any cylinder 2, the engine 1 can be made to simulate the 
variable displacement concept. Furthermore, the great number of cylinders 
in the engine (24 in all) ensures a greater degree of power 
discretization. 
6. Efficient utilization of exhaust heat energy.--By use of the compact 
expander 110, disposed within the rotary member 16. The arrangement also 
avoids the need for a gearbox. 
The force exerted by a pair of rollers 26 on the surface of the cam 17 is 
the difference between the pressure forces in the top and bottom ends of 
the cylinders. This means that in a two-cycle form of the engine, the 
inertia forces due to the reciprocating motion of the piston mass are not 
transferred to the rotary member 16 because they are cushioned by the 
compression of air at either end of the piston. This leads to low 
frictional losses and a relatively long engine life. 
One of the main reasons for the short life of many engine parts in a 
conventional engine is due to the tremendous stresses the engine 
encounters during combustion, This large stress is also transmitted right 
down the crankshaft to all other parts and extreme vibration and eventual 
failure may result. In the engine according to the invention, the stress 
pattern is completely different from that in conventional engines. 
The two rotary cylinder cover plates 18 at opposite ends of the rotary 
member 16 transfer high combustion forces axially through the rotary 
member 16, not through the engine body 4. This results in a 
self-equilibriating stress pattern within the rotary member 16, i.e. a 
stress pattern which exactly balances out the forces applied to it. 
Therefore substantially no stresses are transferred to the engine body 4. 
The rotary member 16 "floats" on its bearings which do not experience any 
significant loadings. 
In conventional engine a piston is provided with a large skirt area which 
absorbs side thrust imposed on the piston by the connecting cylinder. This 
large skirt area is also responsible for high frictional losses of the 
pistion due to the viscous forces in the fluid film lubrication mechanism. 
In the engine 1, a doubleacting pistion is supported by a belt of fluid 
film lubrication disposed between the exhaust ports 8, and thus in a 
cooler region of the engine. This arrangement allows air film lubrication, 
and/or use of linear motion bearings in this region. 
A single-cylinder version of the engine may be provided.