Compound displacement mechanism for simplified motors and compressors

A rotating and reciprocating positive displacement mechanism which draws in a metered volume of gas and then expands or compresses that quantity of gas before expelling it. The mechanism has useful application as a compressor, a compressed gas motor, an expanding vapor engine, or a hot gas engine, where generation of heat by combustion can be either internal or external to the expansion mechanism. The primary advantages of the mechanism over conventional mechanisms used in these applications include (1) few moving parts, (2) easily constructed parts of simple geometry, (3) feasibility of compound operation (i.e. two-stage expansion or compression), (4) relatively constant input or output torque throughout the operating cycle, and (5) relative absence of high pressure peaks during the operating cycle (even when used as an internal combustion engine).

The invention herein disclosed relates generally to rotating displacement 
mechanisms. 
BACKGROUND 
Hot gas engines in general utilize the approximately ideal relationship 
between the pressure, volume, and temperature of gases (i.e. PV=nRT) to 
control conversion of heat to mechanical power. Internal combustion 
engines in particular take in a given volume of air at ambient 
temperature, raise the temperature of that air very rapidly by igniting a 
small quantity of fuel evaporated or dispersed in it, and provide for a 
certain amount of mechanical expansion of the hot combustion products to 
recover some pressure-volume work before the hot gases are expelled from 
the engine. 
An ideal engine/transmission system will recover the maximum amount of work 
from fuel consumes, at any rate dictated by the need for power, using a 
simple and easily constructed mechanism of minimum weight. Conventional 
internal combustion engines, based upon the piston-and-bellcrank 
displacement mechanism in common use since the time of James Watt, fall 
far short of the ideal performance largely because of a limited number of 
practical considerations: 
Combustion Kinetics: Because fuel droplets or particles evaporate and burn 
at finite rates, the temperature of exhaust gases must be somewhat less 
than the value calculated from thermodynamic properties of the fuel and 
the air/fuel ratio; the discrepancy increases as engine speed is increased 
because less time is available for completion of combustion within the 
engine. 
Mechanical Constraints: Because the intake and power stroke displacements 
of a typical piston-and-bellcrank engine are exactly the same, the 
combustion gases are still at a high pressure at the end of a power 
stroke. Escape of this high pressure gas when an exhaust valve opens 
generates considerable noise and forfeits a significant portion of the 
pressure-volume work which could have been recovered if the power stroke 
displacement were sufficiently larger than intake displacement to exhaust 
the hot combustion gases at ambient pressure. 
Load Characteristics: Because the displacement of an engine is specified 
primarily on the basis of its peak power requirement, any effective means 
of averaging the load requirements will permit use of a smaller engine, 
with corresponding reductions in weight and fuel consumption. Furthermore, 
complex multicylinder engines with flywheels of relatively low rotational 
inertia are commonly used whenever the engine is expected to change speed 
rapidly under load, whereas a much simpler and more efficient one-cylinder 
engine of comparable displacement driving a large heavy flywheel at 
constant speed could be used to supply the same amount of power if speed 
variations could be accomplished by a transmission instead of by the 
engine. Load averaging depends on the ability of a power transmission 
system to store or withdraw energy from a storage device (e.g. battery, 
compressed air tank, flywheel, etc.) while continuing to transmit the 
precise amount of power needed to satisfy the load requirements. 
Material Limitations: Because common metallic materials require cooling and 
lubrication to prevent galling and oxidation of sliding surfaces in an 
engine, approximately 30% of available combustion heat must be wasted 
through conduction to a cooling system simply to prevent a conventional 
engine from destroying itself. 
SUMMARY OF THE INVENTION 
The invention described here is a rotating and reciprocating mechanism for 
expanding or compressing gas. This invention has useful application as a 
compressor, a compressed gas motor, an expanding vapor engine, or a hot 
gas engine, where generation of heat by combustion can be either internal 
or external to the engine. 
The rotating and reciprocating mechanism of the subject invention is an 
adaptation of the Tri-Rotor pump (Tri-Rotor, Inc., 36 E. Lawton St., 
Torrington, Conn. 06790), the use of which pump appears to date back to 
the Second World War era. More particularly, the eccentric shuttle of the 
present invention is an adaptation of that pump's shuttle and can be 
compounded with the piston displacement by porting and channels through 
the rotor and the block as hereinafter described. 
The structural components of the subject mechanism are generally similar to 
those shown in U.S. Pat. No. 3,279,445, issued to Robert Karol on Oct. 18, 
1966. Karol, however, made no use of the relative reciprocation of his 
shuttle within the slot in the piston as a second displacement mechanism; 
the only function of his shuttle was to provide a suitable bearing surface 
for guiding the motion of his piston within the rotor slot. His mechanism 
with just three moving parts consequently had only one double-acting 
piston and was capable only of two-cycle, but not four-cycle, operation 
without the use of valves. When he added a second piston, the Karol engine 
with four moving parts could have been adapted to four cycle operation 
without valves, but no means for the required transfer of gases between 
displacement spaces was described. 
Although the detailed description of the operation of this mechanism here 
is related primarily to application as a heat engine, it is understood 
that the minor modifications in porting necessary for its use in the other 
applications could be effected by one skilled in the art. 
In the mechanism employed for use as a hot gas engine according to the 
invention, a fuel/air mixture is admitted to a space displaced by the 
eccentric shuttle on its intake stroke, then compressed on its compression 
stroke. The compressed mixture is then discharged with considerable 
turbulence through a port on the transfer plate pilot boss to a passageway 
containing a continuous ignition source (e.g. a glowing filament or a 
catalytic matrix) so that combustion is much smoother than if it were 
initiated by an instantaneous spark. The burning gas is then led to a 
space displaced by the piston to produce useful work, and it is finally 
exhausted at relatively low pressure because piston displacement is much 
larger than displacement of the eccentric shuttle.

DETAILED DESCRIPTION 
Referring to FIG. 1, an exploded view showing the relationships between 
parts, one can observe that the rotor/shaft 20, the piston 22, and the 
shuttle 24 are the only parts which move during operation of the 
mechanism. One will also notice that there are no valves and no valve 
actuation mechanisms; the flow of gas through the mechanism is controlled 
entirely by displacements and intermittent alignment of ports resulting 
from relative motions of the rotor 20, piston 22, and shuttle 24 with 
respect to each other and to adjoining stationary parts. 
Referring now to FIG. 2, a sequential series of drawings showing the 
relative positions of the rotor face, piston face, and shuttle face at 
15.degree. increments of rotor rotation. It is readily seen that both the 
piston 22 and the shuttle 24 function as double-acting pistons, each 
90.degree. out of phase with the other, and widely differing in their 
displacement volume. The 90.degree. difference in phase provides time for 
transfer of gas from one displacing body to the other, without 
compromising the double-acting characteristic of either body, thereby 
permitting expansion or compression of gas in two stages with a minimum 
number of moving parts; comparable compound expansion or compression of 
two volumes of gas per revolution in a conventional bellcrank-and-piston 
mechanism, by contrast, would require four pistons, four connecting rods 
and a crank, or a total of nine moving parts, plus any additional parts 
which might be required to perform the valving function. 
OPERATION AS A HOT GAS ENGINE 
Although the detailed description of the operation of this mechanism here 
is related primarily to application as a heat engine, it is understood 
that the minor modifications in porting necessary for its use in the other 
applications could be effected by one skilled in the art. 
SHUTTLE INTAKE STROKE 
An air/fuel mixture is supplied from a carburetor or other suitable mixing 
device to an engine intake port connection 28, which penetrates the block 
30 and intersects the rotor bore 32 at a point which is isolated at all 
times from the space displaced by the piston 22, but which corresponds to 
the surface of the rotor 20 near its shoulder. Two diametrically opposed 
rotor intake notches 34 are cut into the cylindrical surface of the rotor 
20 near the rotor shoulder at an axial position such that each notch 34 
and the engine intake port connection 28 in the block constitute the first 
set of intermittently aligned ports. The engine intake port connection 28 
and the two rotor intake notches 34 are sized and positioned such that 
their intermittent alignment allows the fuel/air mixture to flow through 
to one of two shuttle intake passages 36 in the rotor 20 only during the 
half rotation when that shuttle intake passage 36 is required to supply a 
quantity of the fuel/air mixture to an intake stroke of its respective end 
of the shuttle 24. 
When either end of the shuttle 24 approaches completion of an intake 
stroke, the piston 22 is simultaneously moving at its maximum rate and 
approaching the midpoint of its travel. A second set of intermittently 
aligned shuttle intake ports including ports 40 on the floor 42 of the 
rotor cross-slot and ports 44 on the piston bottom 46 are shaped and 
positioned such as to present a large alignment cross-section throughout 
the intake stroke of the corresponding end of the shuttle 24; the loss of 
port alignment at the midpoint of piston travel abruptly and precisely 
terminates the flow of fuel/air mixture from the shuttle intake passage 36 
in the rotor to one end of the shuttle 24 at the completion of the 
corresponding shuttle intake stroke. At this point the rotor has rotated 
180.degree. since the beginning of the shuttle intake stroke. 
SHUTTLE COMPRESSION/TRANSFER STROKE 
At 180.degree. of rotation of the rotor 20, the shuttle 24 reverses 
direction and begins to compress the recently acquired volume of fuel/air 
mixture. At some point between 180.degree. and 360.degree. of rotor 
rotation, a third set of intermittently aligned ports including port 50 in 
the face of the shuttle and port 52 in the transfer plate pilot boss 54 
become aligned and allow the compressed mixture to escape into a 
passageway 56 in the transfer plate 58. By the time the rotor has rotated 
360.degree., the third set of intermittently aligned ports 50, 52 will 
have already closed, so that the compressed gas in the transfer plate 
intake port 52 cannot escape through the shuttle and reduce the volumetric 
efficiency of the succeeding shuttle intake stroke, which is just 
beginning. 
IGNITION 
At 360.degree. of rotor rotation, intake and compression of the fuel/air 
mixture have already occurred, and the mixture has entered a transfer 
passage 56 in the transfer plate 58, which then leads to a space 60 
displaced by the piston. It can be seen from the incremental sequence 
diagram (FIG. 6--360.degree. Rotation), however, that the piston 22 is 
already at midstroke and has already displaced a volume several times 
greater than the entire volume displaced by the shuttle on its 
compression/transfer stroke. If one wishes to avoid rotational 
deceleration of the engine resulting from development of a partial vacuum 
at any time during the piston's power stroke, the fuel/air mixture must be 
ignited and the buring mixture allowed to enter, through a fourth set of 
intermittently aligned ports (described below), the space 60 displaced by 
the piston at or near the very beginning of its power stroke. 
The ignition process need not be precisely timed, because the mixture 
cannot ignite until the third set of intermittently aligned ports 50, 52 
allows it to approach an ignition source provided in the transfer passage 
56, and because the large receding piston face is increasing the available 
expansion volume many times faster than the small advancing shuttle face 
is decreasing it. It is possible, indeed very desirable, to provide a 
continuous source of ignition in the transfer passage 56 in order to avoid 
the extremely high peak pressures typically encountered in conventional 
engines, while simultaneously permitting both the structural requirements 
and the weight of the engine to be reduced. 
Such a continuous source of ignition can include an incandescent coil of 
wire operating at relatively low voltage, suitable for starting the engine 
when it is cold; this arrangement is much simpler, much cheaper, and 
probably more reliable than the coil, contact points, distributor, and 
high voltage wiring commonly used as the spark ignition system for a 
conventional gasoline engine. 
A porous matrix of heat resistant material, impregnated with a catalyst 
which lowers the activation energy for oxidation of the fuel, can be a 
suitable source of continuous ignition when the engine is hot and has been 
operating for some time; this arrangement not only ignites the fuel/air 
mixture, but it improves the fuel efficiency of the engine by reducing the 
amount of unburned fuel entrained in the hot gases exhausted from it. 
COMBUSTION 
If the fuel/air mixture is ignited by a continuous ignition source as it 
first enters the transfer plate intake port 52, combustion is free to 
occur at a rate determined by the volatility and heat content of the fuel 
as the burning mixture passes through the transfer passage 56. If the 
transfer plate intake port 52 is sufficiently small in diameter so that 
the velocity of the fuel/air mixture within it exceeds the rate of 
propagation of the flame front, continuous combustion is forced to occur 
within the transfer passage 56 without danger of damage to the engine 
because of premature detonation and high pressure transients. 
It can be readily seen from the exploded view of the engine that the volume 
of any transfer passage 56 within the transfer plate 58 is independent of 
the operating geometry of the shuttle 24 or the piston 22. The engine 
designer can make this volume as large or as small as he wishes, in order 
to provide adequate time to achieve complete combustion of practically any 
fuel. For example, a low speed engine burning natural gas in air will run 
quite well with essentially no residence time in the transfer passage 56, 
whereas a high-speed engine burning fuel oil or an engine burning 
micronized coal dust in air might require connection of an adiabatic 
labyrinth of considerable size to the transfer passage 56 in order to 
provide a residence time long enough to achieve complete combustion of the 
slower burning fuels. 
It should be noted that, as the residence time is increased by increasing 
the volume of the transfer passage 56, the engine will become 
progressively less tolerant to changes in load. Furthermore, the engine 
designer must provide some positive means for limiting the amount of hot 
pressurized gas escaping from the transfer passage 56 with each piston 
power stroke, so that each piston power stroke receives no more gas than 
piston displacement can expand to near ambient pressure. This is the 
function of the fourth set of intermittently aligned ports, to be 
described below. The elevated pressure within the transfer passage 56 can 
thereby be maintained within narrow limits during most operating 
conditions, and control of engine speed can be controlled by varying the 
fuel/air ratio admitted to the engine intake port connection 28. 
PISTON POWER STROKE 
The power stroke of the piston 22 begins at 270.degree., when the shuttle 
24 is at the midpoint of its compression/transfer stroke and when the 
third set of intermittently aligned ports 50, 52 is just beginning to 
allow the compressed mixture to escape past an ignition source in the 
transfer passage 56 toward a space 60 displaced by the piston. The fourth 
set of intermittently aligned ports including a port 62 at the edge of the 
transfer plate pilot boss 54 and the periphery 64 of the rotor face allows 
the hot pressurized gases in the transfer passage 56 to escape into the 
space 60 displaced by the piston only during the rotation interval from 
270.degree. to some point equal to or prior to 450.degree.; the engine 
designer can design the fourth set of ports in such a manner that any 
average pressure at or above ambient can be maintained within the transfer 
passage while still allowing the piston to expand the hot gas to a 
pressure at or near ambient at the end of the power stroke. 
Since the displacement during the power stroke of the piston 22 may exceed 
the volume required to expand the gaseous combustion products to ambient 
pressure under a number of circumstances (such as starting, idling, or 
operation under very cold conditions or with contaminated fuel), the 
engine designer may wish to connect a check valve at some point along the 
rotor bore 32 in the block 30 between the transfer plate exhaust port 62 
and the engine exhaust port connection 66, in order to minimize rotational 
deceleration and prevent stalling of the engine by admitting cool ambient 
air to the space 60 displaced by the piston during a power stroke whenever 
pressure there drops below ambient. 
PISTON EXHAUST STROKE 
When the piston 22 completes its power stroke at 450.degree. of rotor 
rotation after the beginning of the corresponding shuttle intake stroke, 
the hot gases have expanded to a pressure relatively close to ambient. As 
the piston reverses direction in order to begin its exhaust stroke, a 
fifth set of intermittently aligned ports allows the hot gases to escape 
from the rotor cross slot into the engine exhaust port connection 66. 
Because the pressure of the hot gases is relatively close to ambient, the 
gases escape slowly and generate so little noise that no additional 
muffling device need be provided in the exhaust duct. The fifth set of 
intermittently aligned ports (consisting of the open side of the cross 
slot and a port at the inside wall of the rotor bore 32) continues to 
permit escape of hot exhaust gases throughout the exhaust stroke until the 
piston again reverses direction and is ready to begin another power stroke 
at 630.degree. of rotor rotation. 
OPPORTUNITIES FOR COMBINED CYCLE OPERATION 
Since the efficient operation of an internal combustion engine depends upon 
maintaining the gaseous combustion products at as high a temperature as 
possible until the end of the power stroke, it follows that a more 
efficient engine will improve the opportunity to operate some sort of 
combined cycle, increasing efficiency still further by using the rejected 
heat in the engine exhaust. 
For example, if the temperature of combustion products as they are 
exhausted from the engine can be raised 100.degree. C. by constructing the 
engine of materials with low thermal conductivity and by eliminating the 
engine's cooling system, the temperature differential across a heat 
exchanger to recover waste heat from the exhaust gases also rises by 
100.degree. C. If the heat exchanger is used to boil water or some other 
liquid in order to provide vapor to supplement the pressure against the 
piston during its power stroke, one can expect a net improvement in engine 
efficiency, because only waste heat need be utilized to generate the vapor 
with only a minimal increase in back pressure. Opportunity for the vapor 
to moderate the combustion processes and prevent accumulations of carbon 
deposits within the combustion spaces can be expected to provide 
additional benefits as well. 
SUMMARY OF INTERMITTENTLY ALIGNED PORTS 
Since the displacement motion of the piston within the rotor, constrained 
by bearing surfaces on a rotating shuttle, is described by prior art, and 
since the present invention primarily is directed to the use of the 
relative motion of the shuttle within the piston for displacing gas, it is 
particularly important to understand the operating details and functions 
of the five sets of intermittently aligned ports. 
TABLE I 
______________________________________ 
Summary of Operation of Intermittently Aligned Ports 
Mating 
Set Surfaces Interval Function 
______________________________________ 
1st Engine intake 
0-180.degree. 
Maintain a volume of fuel/air 
connection mixture at nearly ambient 
and rotor pressure at a point convenient 
shoulder for intake by shuttle with 
minimum viscous drag. 
2nd Rotor floor 
0-180.degree. 
Provide quick opening and 
and piston quick closing of a passage of 
bottom minimum restriction for 
shuttle intake strokes. 
3rd Shuttle face 
ca. 270.degree. 
Permit escape of compressed 
and transfer 
to 360.degree. 
fuel/air mixture from shuttle 
plate pilot past an ignition source to 
boss piston expansion space. 
4th Rotor face ca. 270.degree. 
Admit controlled amount of 
and transfer 
to ca. 315.degree. 
hot gas to piston expansion 
plate pilot space. 
boss 
5th Rotor peri- 
450-630.degree. 
Permit piston exhaust stroke 
phery and to expel entire volume of hot 
engine ex- combustion products. 
haust con- 
nection 
______________________________________ 
FIG. 2 is a sequence of diagrams showing the positions of the rotor 20, 
piston 22, and shuttle 24 relative to the block 30 in 15.degree. 
increments of rotor rotation. The engine intake port connection 28 is 
shown by a hidden line extending across the top of the rotor bore 32 and 
subtending a 90.degree. arc at the rotor circumference. The two rotor 
intake notches 34 are shown by hidden lines on the rotor cross slot floor, 
which also subtend 90.degree. arcs about the rotor axis. The combination 
of these two details constitutes the first set of intermittently aligned 
ports. It can be seen from the sequence of diagrams that the rotor intake 
notch 34a which is about to make connection with the engine intake port at 
0.degree. rotation will remain in connection with it until 180.degree. 
rotation. One or the other of the rotor notches is positioned to receive 
the intake gas mixture from the engine intake port connection at all times 
during rotation of the rotor. 
FIG. 3 is an exploded drawing of the rotor 20 and piston 22, showing the 
shape and relative positions of the mating surfaces of the second set of 
intermittently aligned ports. 
FIG. 4 shows the operation of the second set of intermittently aligned 
ports, as seen from a vantage point within the transfer plate, at 
90.degree. increments of rotor rotation; for purposes of illustration, the 
rotor 20 is held fixed and the rotor block 30 and eccentric pin 70 are 
caused to rotate relative to it. The mating portions of the second set of 
intermittently aligned ports are shown superimposed as hidden lines upon 
the faces of the piston and shuttle. The approximately triangular holes 40 
penetrate the floor of the rotor cross slot and connect with the engine 
intake port connection 28 via the corresponding shuttle intake passages 36 
and rotor intake notches 34; the approximately flag-shaped holes 44 are 
recessed into the bottom of the piston and connected to their respective 
shuttle intake strokes by grooves 72 at the ends of the piston cross slot. 
It can be seen that the two mating cavities near the bottom of the 
0.degree. diagram are just approaching conjunction and that this 
conjunction will occur rapidly because the piston 22 is at the midpoint of 
its stroke and moving at the maximum rate permitted by its sinusoidal 
motion relative to the rotor 20. The cross-hatched area in the 90.degree. 
diagram shows the large cross sectional area and minimal viscous drag 
through the port conjunction at a time when the shuttle is drawing in gas 
at its maximum rate at the midpoint of its sinusoidal motion within the 
piston cross slot. The 180.degree. diagram shows the abrupt termination of 
this conjunction at precisely the time when conjunction of the opposite 
set of ports is just beginning. The 270.degree. diagram shows that the 
quantity of gas being compressed by the shuttle in preparation for its 
transfer past an ignition source cannot escape back into the shuttle 
intake passage at any time during the interval from 180.degree. to 
360.degree.; the engine intake port connection continues to supply gas for 
an intake stroke of the opposite end of the shuttle throughout this 
interval, however. 
FIG. 5 shows the operation of the third set of intermittently aligned 
ports, as seen from a vantage point within the transfer plate, in 
45.degree. increments of rotor rotation. The two small holes 50 on the 
face of the shuttle 24 penetrate the body of the shuttle and their 
respective shuttle crowns (ends) and provide auxiliary passageways to 
increase the effective cross section for flow of the fuel/air mixture 
during conjunction of the mating cavities. The large hole 52 to the lower 
right (FIG. 5--180.degree.) of the eccentric pin penetrates the surface of 
the transfer plate and provides a passage for gas to reach a source of 
ignition within a stationary combustion chamber 56. It can be easily seen 
that (1) conjunction does not occur until some time after 270.degree. of 
rotor rotation past the beginning of the corresponding shuttle intake 
stroke, and (2) that conjunction has already been terminated by the time 
the rotor reaches the 360.degree. point. The large flow cross section 
during conjunction is illustrated by the cross-hatched area on the diagram 
corresponding to 315.degree. of rotor rotation. 
FIG. 6 shows the operation of the fourth set of intermittently aligned 
ports, as seen from a vantage point within the transfer plate cover, in 
45.degree. increments of rotor rotation. A given volume of gas, 
illustrated by the cross-hatched area on each diagram, is shown being 
compressed between 180.degree. and approximately 270.degree. of rotor 
rotation, then being transferred past an ignition source and through the 
transfer plate passage 56 between approximately 270.degree. and 
360.degree. of rotor rotation, while expanding against the piston crown 
throughout the interval from somewhat after 270.degree. until 450.degree. 
of rotor rotation. The large hole 62 connecting with the horizontal 
transfer passage 56 and penetrating the transfer plate in the lower left 
quadrant of each diagram comprises one half of the fourth set of ports, 
and the piston expansion space 60 itself constitutes the other half. It 
can be seen from FIG. 6 that the conjunction of these two mating cavities 
occurs soon after 270.degree. (the approximate point at which the fuel/air 
mixture enters the transfer passage and is ignited), and continues until 
some point after 360.degree. of rotor rotation. Both the limits and the 
duration of the conjunction of the fourth set of ports are determined by 
the size, shape and location of the large hole penetrating the transfer 
plate. An engine designer can specify these parameters so that the amount 
of hot pressurized gas admitted to the piston expansion space does not 
greatly exceed the quantity which can be expanded to ambient pressure 
after conjunction of the fourth set of ports has ended. 
FIG. 2 shows the operation of the fifth set of intermittently aligned ports 
in permitting the fully expanded hot combustion products to be expelled 
from the engine at more or less ambient pressure. The 90.degree. diagram 
illustrates the situation at 450.degree. after shuttle intake, wherein 
conjunction of the rotor cross slot and the engine exhaust port connection 
66 is just beginning. Conjunction involves little noise because the hot 
gases at 450.degree. after shuttle intake are not at elevated pressure. 
Since the rotor cross slot and the engine exhaust port connection both 
subtend 90.degree. arcs along the rotor periphery, their conjunction 
extends through 180.degree. of rotor rotation to 630.degree. after shuttle 
intake (also illustrated by the 90.degree. diagram in FIG. 2), when all 
the hot gas has been expelled. 
The interval from 0.degree. (the beginning of shuttle intake) to 
630.degree. (the end of the piston exhaust stroke) is 90.degree. less than 
two full revolutions of the rotor, because reciprocations of the shuttle 
and piston are 90.degree. out of phase, and the gas mixture is therefore 
only compressed for 90.degree. of rotation before the beginning of the 
piston power stroke. 
ADVANTAGES OF THE INVENTION 
For application as a hot gas engine, wherein the pressure of hot gaseous 
combustion products is applied directly to the expansion mechanism without 
substantial exchange of heat to another working fluid, or for application 
as a pneumatic power transmission system, or for a combination of these 
two applications, the invention addresses each of the shortcomings cited 
in the background section (above) for conventional internal combustion 
engines and their transmissions in the following ways: 
INSENSITIVITY TO BURNING CHARACTERISTICS OF FUEL 
Whereas slow-speed low-compression spark-ignition engines in heavy 
equipment in years past commonly ran quite efficiently on low octane 
gasoline or even kerosene, the demand for lighter, more powerful 
high-speed engines in automotive applications forced the development of 
high octane motor fuels which could evaporate and burn quickly enough to 
approach complete combustion during a power stroke of extremely short 
duration. These high octane fuels are more difficult to produce, more 
dangerous to store, and more expensive than their low-octane ancestors, 
and yet their use in conventional automotive engines has still resulted in 
the dispersal of huge quantities of unburned hydrocarbons and carbon 
monoxide, as well as toxic heavy metals along roadsides, parking lots, and 
garages throughout the world. There is sufficient latitude in design of 
the displacement sequence for the invention described here to permit 
temporary removal of the burning mixture from the displacement mechanism 
until combustion is complete and gas temperature is maximized, so that 
usefulness of the invention as a combustion engine is substantially 
independent of the burning characteristics of practically any available 
solid, liquid, or gaseous fuel. 
EXPANSION TO AMBIENT PRESSURE DURING POWER STROKE 
The idea of compounding the expansion of hot gas between a high-pressure 
cylinder of small displacement and a low-pressure cylinder of much larger 
displacement in order to minimize the unrecovered mechanical energy 
equivalent in the hot gas or vapor that is finally exhausted from an 
engine found common use in railroad steam locomotives of the previous 
century. Although such a compound engine is obviously more efficient than 
its uncompounded cousin, the increased weight, complexity, cost, and 
opportunity for heat loss during transfer, limit use of this approach to 
compressors and an occasional large stationary engine. The present 
invention, when used as the expansion mechanism for a hot gas engine 
comprising as few as three moving parts, approximates the benefits of 
compound operation for a four-cylinder four cycle engine of conventional 
design. 
A LOAD-AVERAGING PNEUMATIC TRANSMISSION SYSTEM 
Since any significant simplification of a conventional heat engine is 
likely to interfere with the engine's ability to adapt to sudden changes 
in speed and/or load, complete disclosure of a simplified heat engine, 
sized according to the average demand for power in a typical application, 
will require disclosure of a useful load-leveling transmission system as 
well. Since the invention described herein has straightforward application 
as a compressor or compressed gas motor, the combination of a compressor, 
a reservoir for storage of compressed gas, and one or more compressed gas 
motors constitutes such a load-leveling power transmission system. For 
example, the advantage of driving a vehicle by supply of compressed air 
through a flexible hose to an efficient air motor at each wheel, 
regardless of suspension motions or steering action of that wheel, will be 
particularly apparent to designers of lightweight and low-cost vehicles 
for either highway or off-the-road use. 
USE OF CERAMIC MATERIALS IN COMBUSTION ENGINES 
Processes for fabrication of extremely hard ceramic materials (e.g. silicon 
carbide, silicon nitride, alumina, zirconia, etc.) are being developed for 
the manufacture of parts for "adiabatic" high-temperature engines without 
cooling systems and with little or no lubrication. These materials can 
withstand much higher surface temperatures without galling or oxidation 
than any commonly used metal or alloy can endure. More or less 
conventional engine designs, fitted with ceramic cylinder liners, piston 
caps, and valves, are reportedly delivering efficiency improvements up to 
50% by reducing heat conduction away from burning gases and by reducing 
viscous drag associated with movement of lubricating and cooling fluids. 
Most of this development has been done by people who aspire to supply 
these ceramic materials or parts in large quantity to engine 
manufacturers. 
Ceramic materials, however, suffer from two serious deficiencies in engine 
part applications: 
(1) They are difficult and expensive to fabricate to close tolerances, 
which discourages their use in multicylinder engines with hundreds of 
complex and accurately fitted moving parts, and 
(2) They tend to be shock sensitive, so that the possibility of 
uncontrolled detonation of fuel at any time during the life of an engine 
is likely to result in its catastrophic failure and a substantial risk of 
product liability claims against its manufacturer. 
The extreme simplicity of the mechanism of this invention, the simple 
geometry of its parts, and the gradual nature of changes in displaced 
volume, serve to reduce the importance of these disadvantages of ceramic 
materials when applied to a low-cost lightweight adiabatic internal 
combustion engine.