Heat engine

A heat engine with a compressor, an external combustion chamber from which combustion gases pass through suitable valving to an expander, an air compressor, a heat exchanger where exhaust gases from the expander preheat compressed air which then flows to the combustion chamber, and an accumulator for storing unneeded compressed air from the compressor. The system also has the capability of regenerative braking, i.e. slowing of the engine by employing it as a compressor to compress air which is passed to the accumulator.

BACKGROUND OF THE INVENTION 
The present invention relates to heat engines and more particularly, to a 
novel engine in which the combustion chamber is separated from the 
expander which receives hot gases from the combustion chamber. 
The engines of the invention are thermodynamically similar to the gas 
turbine, and can utilize one or more pistons or other displacement devices 
for compression and expansion. Combustion is external of the displacement 
devices, thereby providing many advantages. The use of a combustion 
chamber separated from the displacement devices provides greater 
flexibility as to fuels used. Thus, solid, liquid or gaseous fuel may be 
utilized. The combustion temperature may be lower and the combustion time 
longer, resulting in more complete combustion, to thereby substantially 
reduce the level of pollutants in the exhaust. In addition, no critical 
ignition timing is necessary in such an arrangement. 
One or more devices, or a portion of the operating cycle of the device, is 
utilized to compress air which is passed through a heat exchanger to be 
preheated while cooling exhaust gases and which is then introduced into 
the combustion chamber. Excess compressed air may be stored in an 
accumulator for subsequent use when necessary, for example, during periods 
of peak power demand or when the engine is cold. 
During braking, regenerative braking may be achieved whereby the engine is 
slowed while compressing air in the compressor which is passed to an 
accumulator for storage and subsequent use when needed. The compressor may 
be disconnected on start-up so that there is very low starting load. The 
stored compressed air is also available for powering auxiliary equipment 
as well as for meeting peak power demands and for engine start-up. The 
availability of compressed air for start-up provides easy cold weather 
starting and if desired enables the fuel to be cut off completely on idle 
since the engine can be restarted immediately on demand in view of the 
availability of compressed air which can be passed through the system to 
the expanders. 
The engines of the invention may in appropriate sizes be employed in a wide 
variety of applications. For example, when employed to power an 
automobile, the engines of the invention would have increased efficiency, 
reduced exhaust levels of pollutants and heat, fast starting capability, 
compressed air availability, dynamic braking, and instant power 
availability. For buses and trucks, the saving of braking energy would be 
a particularly significant factor. The engines of the invention would also 
find application in locomotives, stationary power plants, marine engines 
and airplanes. A primary advantage of use in aviation would be high 
horsepower availability for the size of the engine during take-off because 
of the availability of the stored compressed air for use as a take-off 
assist. 
Another advantage of the invention resides in its great versatility, 
engines can be made with virtually any number (even or odd) of cylinders, 
and a wide range of compressor/expander ratios (from 1:1.5 to 1:10 or 
about 5) can be used. The invention can also be embodied in a turbine 
form. 
The above and other objects, features and advantages of the invention will 
become more apparent as this description proceeds.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to FIG. 1, where a preferred embodiment of the invention is 
illustrated, the system of the invention includes an air compressor 
comprising a pair of cylinders 10 in which there are pistons 12. Air is 
drawn into the cylinders from an air inlet duct 14 into a cylinder in 
which the piston is in the retracted position which in the illustrated 
embodiment is the right hand cylinder 10. On the upstroke, air is 
compressed and forced into air supply duct 16. Suitable reed or poppet 
valves 13 are provided both at the intake and exhaust openings of 
cylinders 10 to permit the extrance of fresh air and the discharge of 
compressed air at the appropriate times in the cycle of movement of 
pistons 12. The compressed air is then passed through a valve 18 which has 
a sliding spool member 20 which permits the compressed air to be passed: 
(a) through duct 22 into an accumulator tank 24 where compressed air is 
stored and (b) into a duct 26 which leads to an air preheater 28. Valve 18 
controls the diversion of the comressed air into a portion of the air 
which flows to accumulator 24 and the remainder to the air preheater 28. 
In the preheater 28 the air is heated by the heat in the exhaust gases by a 
heat exchanger coil 30. Heated air leaves the preheater through line 32 
and enters into the upper end of an external combustion chamber 34. In the 
illustrated embodiment, a fuel pump 36 pumps any suitable fuel such as a 
liquid fuel, gaseous or a solid fuel through fuel inlet line 38 into the 
combustion chamber where the fuel is ignited by a conventional suitable 
ignition means 40. By relatively simple modifications, any liquid or 
gaseous fuel may be burned in the combustion chamber. The resulting hot 
combustion gases, which may be at a temperature on the order of 
2000.degree. F. and are now at elevated pressure, pass out duct 42 at the 
lower end of the combustion chamber through cam operated valves 46. The 
valves are designed to be opened approximately 40.degree. of rotation of 
the crank for running in the cases of valve 46 and valve 130 in FIG. 2, to 
allow the high pressure gases into piston chamber 44 and to force one of 
the pistons 48 downwardly on the power stroke. When the piston reaches the 
bottom of its stroke, an exhaust valve 50 opens to allow the spent gas to 
exit via passageway 52, around heat exchange coil 30 in the air preheater, 
and then out exhaust duct 54. 
In the embodiment shown, and as illustrated in FIG. 3 and described more in 
detail below, the cams provide for one amount of dwell for running, and 
another different amount of dwell for starting. In order to be 
self-starting, the invention requires three power pistons at the minimum, 
but any larger number is also possible for different specific embodiments 
of the invention. In order to determine the amount of dwell necessary for 
differing numbers of power pistons, one divides 360 by the number of 
pistons, and then adds a small number of degress, two degrees presently 
being preferred, in order to assure that the valves will overlap in 
operation. Further, as mentioned above, about 40 degrees of dwell for the 
running mode is required for each cylinder regardless of the number of 
cylinders in the engine. However, this amount can be varied if needed, as 
is known to those skilled in the engine arts. 
Pistons 48 are mounted on piston rods 56 which are connected to a 
crankshaft 58. The crankshaft is connected to the vehicle or other 
transmission or other power take-off means schematically indicated by 
reference numeral 60 via a suitable gearing system including pairs of 
gears 62, 63, pneumatic clutches 64 and a clutch 68 in engagement via a 
shaft 66 connected to transmission 60. Pistons 12 of the air compressor 
are also connected to the crankshaft 58. By disengagement of the 
appropriate one of the clutches 64, it is possible to inactivate the 
expansion cylinders 44, for example, during braking or idling, or 
alternatively, to deactivate the air compressor, for example, at times of 
peak power output such as when accelerating. 
Operation of the engine is regulated by suitable control means 
diagrammatically illustrated as including a control monitor 70 which 
receives input signals such as a signal indicative of the pressure in the 
combustion chamber via line 72 and an indication of the temperature of the 
gases going to the expansion cylinders from the combustion chamber via 
temperature sensor line 74. In addition, monitor 70 receives an input 73 
from the action of the driver or operator, for example, when depressing 
the accelerator pedal or brake pedal. Monitor 70 is also connected to the 
fuel pump 36 to appropriately adjust the flow of fuel to the combustion 
chamber, and to the spool valve 20. The monitor 70 could include a small 
computer for the control operations. 
The monitor also controls the pneumatic clutches 64 as a function of engine 
operating temperature and pressure, as well as the valve 18. 
In operation, there are three primary operating modes: (1) steady state 
mode, (2) a regenerative braking mode, and (3) a peak power mode. In the 
steady state mode, which the description has been primarily directed to up 
to this point, air is drawn into the compressor 10 and compressed air is 
forced by pistons 12 through duct 16, valve 18, and air preheater 28 into 
combustion chamber 34. In combustion chamber 34, fuel is ignited and the 
resulting hot combustion gases develop the operating pressure of the 
engine. The high pressure gases now pass into expansion cylinders 44 and 
give up energy which is transmitted via crankshaft 58 and the associated 
structure to transmission 60 to drive a vehicle, or other end use. After 
the expansion stroke, the spent combustion gases pass through the air 
preheater 28 where additional energy in the form of heat is reclaimed to 
preheat the air going to the combustion chamber. 
In the regenerative braking mode, each revolution of the engine driven by 
inertia, for example, of a fly wheel, delivers one volume of compressed 
air from compressor 10 through valve 18 whose spool member 20 is now in a 
position blocking flow of air into duct 26 and permitting the air to flow 
only through duct 22 into the accumulator 24. At this time, the right side 
clutch 64 is disengaged due to a lowering of pressure in the combustion 
chamber whereby the expansion cylinders are mechanically and pneumatically 
disconnected from the compressor. The compressed air which is being stored 
in the accumulator 24 is then available for future use. 
As the vehicle comes to a stop, if desired, the pneumatic clutch may be 
re-engaged rather than stall the engine and spool valve 20 shifted to a 
position which will permit a low level of compressed air to pass through 
the system to cylinders 44 in an amount sufficient to keep the engine 
turning over. When the operator starts the car up from a stop, or when the 
peak power mode is otherwise demanded, as for example for passing, 
depression of the accelerator pedal will further shift valve 20 to permit 
the flow of a greater amount of compressed air to the combustion chamber. 
In the event that the operator desires peak power mode operation, for 
example, when quickly starting after a stop or in passing another vehicle, 
the left side clutch 64 may be disengaged thereby disengaging the 
compressor 10 from the expansion cylinders. The absence of the compressor 
torque drain during this mode provides a large power output even for a 
small bore engine for a short duration. In this mode, the valve 20 shifts 
to a middle position which permits free passage of stored compressed air 
in accumulator 24 through air preheater 28 and into combustion chamber 34. 
FIG. 2 illustrates another embodiment of the invention in which air 
compression takes place in the displacement chambers during one stroke of 
the pistons and the remaining strokes of the cycle are expansion strokes 
in which high pressure combustion gases drive the pistons. To simplify the 
illustration, a single piston cylinder 80 is disclosed and it will be 
understood that for most applications, such as in vehicles, a plurality of 
such cylinders will be employed, as is customary. 
A piston 82 reciprocates within cylinder 80 and has a piston rod 84 which 
is connected to a crankshaft 86 which has a fly wheel 88 at one end. A 
housing 90 encloses the crankshaft and the bottom of the housing may 
function as an oil sump. 
During the air compression stage, fresh air enters the cylinder through 
intake 92 and a suitable valve such as a reed valve 94 due to the 
descending piston lowering the cylinder pressure and opening valve 94. On 
its return stroke, piston 82 compresses the air, closes inlet valve 94 and 
forces the compressed air out through a spring biased discharge valve 96 
to a surge tank 98 and then into a three-way valve 100 which has a sliding 
spool 102. Valve 100 is comparable to the valve 18 of the FIG. 1 
embodiment and performs in the same fashion. With spool member 102 in the 
middle position, air passes through valve 100 into line 104 to the air 
preheater 106 for indirect heat exchange with spent gases going to 
exhaust. When the spool member 102 is moved to its extreme left position, 
the air passes solely through line 108 to an accumulator 110. This would 
be the position of the valve during regenerative braking. In this 
embodiment there is an additional accumulator or air reserve tank 112 in 
communication with accumulator 110 through a one-way check valve 114. When 
the pressure in accumulator 110 reaches a given level, valve 114 opens and 
the pressurized air flows into reserve tank 112 which has a relief valve 
116 for safety purposes. Air from reserve tank 112 may be passed through 
line 118 and a valve 120 into the surge tank 98 when needed. In this 
fashion, the system would always have sufficient air to start the engine 
when it is cold. 
When valve 100 is in a middle position, the flow of air from the surge tank 
is divided into two streams, part of the air flowing to accumulator 110 
and the remainder to the air preheater 106. 
The preheated air from air preheater 106 passes through conduit 122 into 
the upper end of a combustion chamber 124 which is comparable to the 
combustion chamber 34 of the FIG. 1 embodiment. The air enters the 
combustion chamber concentrically around a fuel nozzle 126 which 
discharges fuel into the combustion chamber 124 for ignition by an igniter 
128. The high temperature and pressure combustion gases enter the cylinder 
80 upon the opening of an expander intake valve 130 which receives the 
combustion gases from discharge conduit 132 of the combustion chamber. The 
high pressure gases push piston 82 downwardly,rotating the crankshaft to 
provide useful output power, such as for propelling a vehicle. When 
crankshaft 86 has rotated about 40.degree. from the top dead center, valve 
130 closes and at the bottom dead center exhaust valve 134 is opened so 
that the spent gases are discharged through line 136 through the air 
preheater to exhaust duct 138. 
A timing belt 140 or other suitable control mechanism is used to turn an 
actuating cam 142 at, for example, about 5:1 or other selected engine 
compression/expansion ratio. This cam and related valves 100, 130 and 134 
operating via suitable control means, will place the engine into normal 
operation, regenerative braking or peak power mode in a manner analogous 
to that explained above as to FIG. 1. 
The invention is capable of a large variety of compression/expansion 
ratios, the 5:1 ratio described above is by way of example only. As is 
well known in thermo-dynamics and the engine arts, changing the ratio will 
have an effect on the operating temperatures, the materials used, and the 
efficiency of the engine. By simply changing all of the suitable gears, 
pulleys, belts or other control means, the invention teaching can be 
accommodated in any of the kinds of engines in which it is useful (piston, 
turbine, screw or other types) and depending upon materials, fuel used, 
ambient temperature, operating temperature, and the like, different ratios 
can be used. Overall,in all of these different combinations, ratios in the 
range of 1:1.5 to 1:10 could be used. It is thought that, at the present 
state of the art, ratios higher than 1:10 are not practical since the 
operating temperatures would be too demanding of the materials and of the 
engine itself. 
The opening and closing of expansion inlet valve 130 is regulated by a 
two-armed lever 144, a rod 146 which has its lower end disposed in a 
recess in block 148 connected to a cam follower 150 associated with a cam 
152 on crankshaft 86. When cam 152 is in the position as shown, rod 146 is 
depressed and via the two-armed lever 144, valve 130 is closed. When a 
high point on the cam 152 is in contact with cam follower 150, rod 146 is 
elevated causing the valve 130 to open. 
Actuation of the discharge valve 134 is accomplished in a similar fashion 
via a two-armed lever 154, rod 156, lifter 158, cam follower 160, and cam 
162 on the crankshaft. 
In order for the engine shown in FIG. 2 to be self-starting, as explained 
above, three such cylinders will be needed. In such an engine having three 
cylinders of the type shown in FIG. 2, only some of the components need be 
duplicated for each cylinder, and many of the components will be in common 
to serve all of the cylinders in the engine. Among the common components 
may be the combustion chamber 124, the accumulator means, the heat 
exchanger, the controller 165, and much of the valving and other secondary 
pieces of apparatus, all as will be evident to those skilled in the engine 
arts. This will include any manifolding of different flows through the 
engine as is common with multi-cylinder engines. 
During a regenerative braking cycle of operation, in addition to the flow 
of fuel being interrupted, valves 130 and 134 are inactivated. This 
inactivation is accomplished via a solenoid valve 164 which, when in a 
down position, permits high pressure air to pass through line 166 (see 
FIG. 3) from a suitable source, for example, the accumulator, and elevates 
piston 168 in an air cylinder 170. Elevation of the piston 168 of a 
control rod 172 attached thereto cancels the action of cams 152 and 162 by 
inactivating the pneumatic system associated with the cams since elevation 
of rod 172 opens a return passage to oil reservoir 174. Thus, elevation of 
cam followers 150 and 160 by cams 152 and 162 is not effective to elevate 
the valve lifters for rod 146 leading to inlet valve 130 or for 156 
leading to exhaust valve 134. 
At the same time, by a suitable control mechanism, which might include the 
air cylinder 170, spool member 102 of valve 100 is shifted to the extreme 
right position so that the surge tank 98 communicates only with 
accumulator 110. Now on the down stroke of the piston, air is sucked 
through intake 92 and valve 94, compressed as the piston moves up, and the 
compressed air is forced through valve 96 and surge tank 98 into 
accumulator 110 and, if necessary, into reserve tank 112. 
At the conclusion of the braking mode, when the engine is restarted, the 
stored compressed air leaves accumulator 110 through valve 100 which has 
now moved to a position permitting this flow, and eventually into cylinder 
80 through power inlet valve 130. Thus, the engine may be restarted 
although it was not idling. If the engine had three cylinders or more, 
there would not be a dead spot in the engine and therefore this high 
pressure air would cause the engine to function as an air motor and start 
up without idling. The present engine is a very low emission engine since 
fuel loss during idling is substantially reduced and may be completely 
eliminated if the flow of fuel ceases completely when fuel is not needed. 
Such fuel cut-off can be readily accomplished as needed by those skilled 
in the engine arts. 
The starting apparatus is shown in the lower portion of FIG. 3. High 
pressure air is inlet through conduit 159, and acts on the movable part 
152 of the two level cam. The left hand side 153 is fixed to the shaft 
155, by means not shown, and the high pressure air from conduit 159 enters 
into a space 163 between the two cam portions 152 and 153 via an orifice 
161 formed through the shaft. A compression spring 157 normally urges the 
movable cam portion 152 to the left, towards the fixed cam portion 153. 
Suitable rotating seals, sliding seals, and the like are provided wherever 
needed, as is well known to those skilled in the engine arts. Thus, for 
starting, no air is provided through the conduit 159, and the spring 157 
will urge the starting 122.degree. degree dwell time cam 152 under the cam 
follower 150. After starting is accomplished, the control means will 
provide air through the conduit 159, and the sliding cam portion 152 will 
be forced to the right against the pressure of the spring 157. This will 
bring the left hand part of the outer cam shell, the part marked 
40.degree. in the drawing, under the cam follower 150, and the engine will 
be in the "run" mode, as opposed to the starting mode. 
In the full power mode of operation, a solenoid valve 176 is employed to 
cancel the action of cam 142 so that there is no compression. This may be 
accomplished in various ways, for example, depression of the solenoid 
valve 176 may cause flow of air against the face of an air cylinder 178 
moving valve 180 to an open position so that oil in chamber 182 may return 
to oil reservoir 184. Since hydraulic pressure is not maintained in 
chamber 182, depression of cam follower 186 associated with cam 142 does 
not result in hydraulic pressure being applied against piston 188 
associated with rod 172. 
In normal operation, for a one cylinder engine or for each cylinder of a 
multi-cylinder engine, cam 142 rotating at about one-fifth or other 
selected ratio with respect to engine expander/compressor ratio is 
effective through depression of cam follower 186 and the hydraulic fluid 
acting upon the piston to cancel the action of the valve lifters 
associated with rods 146 and 156 in time as needed with respect to 
operation of the cams since elevation of the rod 172 permits oil to return 
to reservoir 174. 
Referring now to FIG. 4, there is shown an embodiment wherein the invention 
teaching has been applied to an engine operating using turbines. Parts the 
same as or closely similar to parts already described above in regards to 
FIG. 1 are indicated by the same reference numeral and an "a". The basic 
difference is that a turbine compressor 190 is the displacement device, 
and another turbine 192 is used as the power or expander device. The full 
teaching of the invention including the accumulator 24a, the valving 18a, 
the heat exchanger 30a, the external combustion chamber 34a, and 
especially the clutches 64a, are used in this turbine based embodiment of 
FIG. 4, in common with the other embodiments described above in regard to 
FIGS. 1, 2 and 3. 
The turbine form of the invention is deemed to have particular advantages 
and utility in automotive use, since by suitable operation of the clutches 
64, the expander or power turbine 192 can be isolated from the load 
imposed by the compressor turbine, which is particularly advantageous when 
the invention is used in the power mode, as described above. This provides 
a significant step forward for the present invention in its turbine mode, 
as compared to conventional turbine engines used in automobiles. Such 
conventional turbine engines are chronically sluggish in automotive use. 
By disconnecting the compressor 190 for power operation, this sluggish 
performance disadvantage of the prior art is overcome. 
In addition to turbines, as is now clear , other sorts of fluid 
displacement devices could be used in place of turbines or pistons as 
illustrated, for example, gears, screws, vanes, bellows, diaphragms, and 
the like, and combination of such devices in one engine, are all deemed 
possible, as can be engineered by those skilled in the engine arts using 
the teachings of the invention. 
As another embodiment,the combustion may be external of the power fluid 
circuit. In such a case, a combustion chamber could be located in the 
bottom of the air heater in lieu of where it is illustrated in FIGS. 1 and 
2. The power fluid would be pressurized air, and the spent power fluid 
would be the oxidizer for the combustion chamber. The power fluid would be 
heated and pressurized by indirect rather than direct heat exchange. 
In similar fashion, the air from the air heater could be further heated and 
pressurized to obtain the power fluid by radiant heat from the sun acting 
on the air while in line 32 of FIG. 1 or conduit 122 of FIG. 2, as 
schematically indicated thereon. 
Thus, it will be observed that this engine can be operated either as an 
I.C. (internal combustion--internal to the power fluid circuit) or E.C. 
(external). If the engine is operated as an E.C., the exhaust from the 
power cylinder(s) is free from the products of combustion and may be used 
as the oxidizer for combustion of the fuel (solid, liquid or gas--any fuel 
that would leave a residue or harmful ash inside the engine will be burned 
externally). A shutter or throttle valve 107 would direct the hot exhaust 
air through or around the burning fuel as needed, using a by-pass pipe 
109, as needed. For solid fuel, particle size would determine fire 
response time, as is known. 
The ability to burn solid fuel particles (saw dust, pulverized straw, hay 
etc.) makes engines of the invention attractive as a power plant for farm 
tractors, etc. Solar radiation heating, as a source or in addition for 
preheating, is another available option for these engines and could be 
directed at the conduit between the preheater and power cylinder (FIGS. 1 
and 2). 
While the invention has been described in detail above, it is to be 
understood that this detailed description is by way of example only, and 
the protection granted is to be limited only within the spirit of the 
invention and the scope of the following claims.