US3610215A

US3610215A - Gas generator

Info

Publication number: US3610215A
Application number: US878787A
Authority: US
Inventors: James S Carter
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-11-21
Filing date: 1969-11-21
Publication date: 1971-10-05
Anticipated expiration: 1988-10-05

Abstract

A gas generator in the form of a self-starting two cycle free piston internal combustion engine which generates hot exhaust gases and steam as required by the load. A reciprocating piston assembly comprised of three-coupled pistons compresses air in a combustion cylinder to the point of fuel ignition, pumps scavenging air, and compresses and stores a volume of air for recycling the generator. A novel valve arrangement responsive to gas consumption activates the cycling of the piston assembly.

Description

United States Patent [72] Inventor James S. Carter 1937 Grace Ave. Apt. #4, Hollywood, Calif. 90028 [21] Appl. No. 878,787

[22] Filed Nov. 21, 1969 [45] Patented Oct. 5, 1971 [54] GAS GENERATOR 13 Claims, 4 Drawing Figs.

52 US. Cl 123/46 R, 60/13,123/46 SC [51] lnt.Cl F02b 71/00 [50] Field of Search 123/46 R,

46 SC, 46 B; 60/13 [56] References Cited UNITED STATES PATENTS 2,462,745 2/1949 Horgen... 123/46 2,849,995 9/1958 Lewis 123/46 2,933,884 4/1960 Foster 60/13 F 3,024,591 3/1962 Ehrat et al. 123/46 X 3,188,805 6/1965 Gahagen 123/46 X 3,314,403 4/1967 Bouvier et al...; 123/46 FOREIGN PATENTS 840,047 7/1960 Great Britain 123/46 754,168 9/1952 Germany 123/46 Primary ExaminerWendell E. Burns Att0rneySpensley, Horn & Lubitz ABSTRACT: A gas generator in the form of a self-starting two cycle free piston internal combustion engine which generates hot exhaust gases and steam as required by the load. A reciprocating piston assembly comprised of three-coupled pistons compresses air in a combustion cylinder to the point of fuel ignition, pumps scavenging air, and compresses and stores a volume of air for recycling the generator. A novel valve arrangement responsive to gas consumption activates the cycling of the piston assembly.

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BY M% GAS GENERATOR BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to generator of power gas and, more particularly, to a self-starting free piston reciprocating engine in which a mixture of steam and power gas is produced by the combustion of fuel.

2. Prior Art Hot compressed gas, hereinafter referred to as power gas, is commonly used to power such devices as gas turbines and steam engines. One common method of generating power gas is by the combustion of fuel in an internal combustion engine.

The exhaust gases of the engine are piped to the gas turbine or other load instead of being allowed to escape to atmosphere as is done with mechanically loaded internal combustion engines.

Some loads are relatively constant, that is, exhibit a constant or only moderately varying rate of power gas consumption. Gas generators disclosed by the prior art can be designed to satisfactorily supply the relatively constant demand of this type load.

Other loads present widely fluctuating requirements for power gas to the generator. Such demands have heretofore been very difficult to supply since the speed range of internal combustion engines is limited. For example, when the demand falls to a small fraction of full output or to zero for some period of time, the generators disclosed by the prior art must be stopped and restarted on some schedule depending on the load requirements or if left running continually must have their output stored or vented to the atmosphere. Such procedures are bothersome, expensive and wasteful.

The present invention overcomes this problem by utilizing a novel valve arrangement which makes each generator engine cycle independent of every other engine cycle. Engine speed, that is, the number of cycles per unit time is dependent wholly on the requirements of the load since each generator cycle is independently initiated based on the sensing of a predetermined quantity of power gas consumption. Thus, a smooth and automatic accommodation to the load is made by the present invention from zero consumption to full output. Each cycle of operation is substantially identical to every other cycle in terms of duration, fuel consumption, air consumption, etc. The net speed changes because of the change in the number of cycles per unit time rather than the character of the cycle itself.

Prior art gas generators do not have constant cycle characteristics but instead achieve output variations by varying the character of the cycle itself as, for example, by varying the quantity of fuel injected per cycle. Such methods result in richer fuel mixtures at some speed settings than at others with the result that an excessive amount of harmful smog producing pollutants is present in the power gas and eventually may find its way to the atmosphere. This invention, because of its constant cycle characteristics, can be set for most complete combustion (minimum pollutants) at all rates of consumption.

SUMMARY OF THE INVENTION The present invention is basically a two-cycle internal combustion engine in which the hot exhaust gases constitute the entire useable output. In accordance with the presently preferred embodiment of the invention, a piston assembly, comprised of three pistons, reciprocates in response to the demand of the load. The assembly is propelled in one direction by the expansion of a burning fuel-air mixture and in the other by compressed air. The cycle is initiated by the release of energy stored in the form of compressed air. The air, compressed and stored during the burning phase of a revious cycle, is brought to bear on one of the pistons of the piston assembly thereby causing the piston assembly to move. Piston assembly motion compresses the air contained in a combustion cylinder causing its temperature to rise to a temperature sufficient to cause fuel ignition. Fuel is injected into the combustion cylinder after the compression stroke, and due to the high temperature of compression, ignition takes place driving the piston assembly back. The recycling air is recompressed and returned to its storage chamber and is thus available for the next cycle. At the same time, a third piston compresses atmospheric air to be stored in a second storage chamber for use in scavenging the combustion cylinder.

So long as there is no demand for gas, the pressure in the combustion chamber remains relatively high and a master control valve prevents the stored air in the first chamber from initiating another cycle. Gas demand reduces the pressure in the combustion cylinder and allows scavenging air to enter the cylinder. Flow of scavenging air out of its storage chamber causes a reduction in scavenging air pressure which in turn causes the master control valve controlling the recycling air to open, thus initiating a new cycle. This novel method of controlling the recycling air allows the generator to supply a wide range of gas demand extending from zero to the maximum capability of the unit, automatically adjusting to the load. Waste heat from the combustion cylinder is utilized to generate steam which is mixed with the exhaust gases increasing the net efficiency of the unit.

It is a primary object of this invention to provide a power gas generator which is self-starting.

Another object of this invention is to provide a power gas generator which can efficiently supply power gas to steam engines and turbines designed to operate over a wide range of speeds and loads.

Still another object of this invention is to provide a power gas generator in which the speed of operation is controlled by the demand of the steam engine or turbine being powered by it.

Still another object of this invention is to provide a power gas generator in which the heat of combustion conducted through the cylinder walls of the combustion chamber is used to make steam which is mixed with the power gas.

The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawings in which a presently preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross section of a side view of the presently preferred embodiment of the invention.

FIG. 2 is a cross section taken through plane 22 of FIG. 1.

FIG. 3 is a cross section taken through plane 33 of FIG. 1.

FIG. 4 is a cross section taken through plane 4-4 of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is comprised of three basic portions, a motor section, a scavenging air pump, and a recycling section.

Referring to FIG. 1, the motor section contains piston 13 disposed within combustion cylinder 3, check valve 5, passageways 4, and fuel injection nozzle 19. The scavenging air pump is represented by piston 17, cylinder I4, and

check valves

24, 16, and 22. Finally, the recycling section comprises cylinder 11, piston 12, chamber 10, check valve 23. and master control valve 9.

Free piston gas generators disclosed in the prior art, such as the Bouvier et al. US. Pat. No. 3,3l4,403, disclose the same general sections as are in this invention, but as will hereinafter become evident, the novel arrangement of the recycling section and the improved scavenging air pump leads to the substantial performance and other advantages of the present invention over the prior art as previously discussed.

Power gas, ready for consumption, is stored in chamber 2 and, flows to the load through conduit 34. Throttle 1 controls the flow. Passageways 4 connect chamber 2 to the combustion cylinder 3 when piston 13 is in its lowest position, the quiescent state of the generator.

If, when the generator is in its quiescent state, throttle l is opened, stored power gas will flow from chamber 2 and cylinder 3 to supply the load and as a consequence the pressure therein will drop. When the pressure drops to below the pressure of the air contained in scavenging air reservoir 6 (a pressure which may, for example, be about 170 p.s.i.) check valves 5 open allowing scavenging air to enter combustion cylinder 3. As gas continues to flow through conduit 34, the pressure continues to drop until the pressure in chamber 8, connected to reservoir 6 through pipe 7, falls from the above mentioned higher pressure to a predetermined value, for example 150 p.s.i. Master control valve 9 now has 150 p.s.i. on one side of its actuator 37 and the pressure in chamber on the other. Chamber 10 contains stored recycling air which, in the example being used, is at 170 p.s.i. as is discussed later. The greater pressure in chamber 10 as compared to chamber 8 causes master control valve 9 to open. Recycling air pressure from chamber 10 applied to piston 12 causes the piston assembly consisting of

pistons

12, 17, and 13 to move upward compressing the air in combustion cylinder 3. At the same time air in chamber 14 is transferred to chamber 15 through check valve 16.

As air in cylinder 3 is compressed it, of course, heats in accordance with the well known gas laws and near the top of its travel, piston 17 engages fuel injection control rod 18 causing fuel to be injected into cylinder 3 through fuel nozzle 19. Fuel, such as diesel fuel, from a tank, not shown, is supplied through tube 20. Heat from the compressed gas ignites the fuel causing the pressure in cylinder 3 to increase and the piston assembly to move downward.

Prior to combustion, when the piston is at the top of its travel, passageway 36 is uncovered allowing air in tube 7 to enter cylinder ll and equalizing the pressure in chambers 8 and 10. The master control valve 9 then closes. As the piston assembly moves downward, air is compressed in cylinder 11 and flows into chamber 10 through check valve 23 until, at the bottom of the stroke, chamber 10 contains air at a pressure depending on the geometry of the pistons, cylinders, and chambers. In the example being cited, this pressure is 170 p.s.i.

At the same time air in chamber 15 flows through check valve 22 and tube 7 into chambers 6 and 8 replenishing the scavenging air supply, building its pressure back to 170 p.s.i.; this pressure also being a function of the geometry of the parts.

The prior art, such as Bouvier et al. U.S. Pat. No. 3,314,403 discloses a single stage scavenging air pump compressing the scavenging air on the compression stroke of the motor piston. The present invention, in the preferred embodiment, uses a two stage scavenging air compressor which presents a lighter load to the recycling section since the major portion of scavenging air compression takes place on the power stroke rather than the compression stroke of the motor section piston.

When the passageways 4 are uncovered, burned gas flows into chamber 2 and thence out through conduit 34.

When the pressure in chamber 2 falls due to gas flow through conduit 34, the cycle is repeated providing a continuous flow of gas as required. If the throttle is closed removing the demand, the generator stops automatically, since the cycle is activated by a drop in pressure of the power gas.

Master control valve 9, which has no counterpart in the prior art, prevents the recycling air stored in chamber 10 from acting on recycling piston 12 until sufficient power gas has been consumed by the load to require replenishment.

When there is no demand and the unit remains idle for some time the small amount of gas which can leak past piston 13 is prevented from entering chamber 14 by

seals

30, 31 and 32. Any leakage past seals 30 and 31 is exhausted to atmosphere through opening 33.

Water jacket 25 is filled with water through tube 28 to a level determined by float valve 27. Heat from combustion in cylinder 3 causes the water in jacket 25 to boil and when sufficient pressure is built up the steam enters chamber 2 through check valve 26. If a source of high pressure water is not available, a small steam engine pump can be driven from tube 29 to supply tube 28.

Initial startup of the generator may be accomplished by pressurizing

chambers

2, 6 and 10 to, in the example cited, p.s.i. or to whatever is the design quiescent scavenging air pressure of the particular unit, which may be more or less than 170 p.s.i. After initial pressurization,.opening of throttle 1 will initiate operation and maintain the proper pressures as described.

For convenience, the invention has been described using a piston and cylinder as a force summing device, however, it will be evident to those skilled in the art that other force summing devices such as diaphragms or bellows would be as suitable. Reference to pistons and cylinders herein should be understood, therefore, to include other force summing devices.

What has been described is a novel and improved power gas generator. The preferred embodiment has been shown with a single piston assembly for convenience and ease of presentation but it will be obvious to those skilled in the art that this invention lends itself to the configuration of two opposed piston assemblies, common in the free piston engine art as a vibration reducing measure. Various other modifications will be apparent to those skilled in the art and are considered to be within the spirit of this invention as set forth in the appended claims.

lclaim:

l. A gas generator comprising:

a. A combustion cylinder having inlet and exhaust ports;

b. means for introducing fuel into said combustion cylinder;

c. a first piston slidable within said combustion cylinder;

d. a scavenging air pump for supplying compressed air to said combustion cylinder;

e. a first air storage chamber in communication with said scavenging air pump and with said combustion cylinder for storing the compressed air provided by said scavenging air pump;

f. a first valve controlling the flow of air between said first air storage chamber and said combustion cylinder;

g. a second cylinder spaced from said combustion cylinder;

h. a second piston coupled to said first piston and positioned within said second cylinder:

i. a second air storage chamber adapted to store air compressed by the motion of said second piston in said second cylinder whereby substantially all of the air from said second cylinder is stored in said second air storage chamber during a portion of each cycle of operation; and

j. a second valve controlling the flow of air between said second storage chamber and said second piston, whereby actuation of said second valve allows compressed air from said second storage chamber to act on and move said second piston thereby causing said first piston to compress the gas in said combustion cylinder.

2. A gas generator as defined in claim 1 wherein said second valve is responsive to a drop in pressure in said first air storage chamber.

3. A gas generator comprising:

a. first, second and third concentric cylinders spaced axially;

b. first, second and third pistons slidable within said first, second and third cylinders respectively, said pistons being coupled;

c. a first air storage chamber;

d. first and second check valves connecting said first and second cylinders respectively to said first air storage chamber, whereby air may flow from said second cylinder into said first air storage chamber, and from said first air storage chamber into said first cylinder;

e. a second air storage chamber;

f. a pressure responsive valve connecting said second air storage chamber with said third cylinder, said pressure responsive valve being responsive to the pressure in said first air storage chamber, whereby air in said second air storage chamber is allowed to flow into said third cylinder when pressure in said first air storage chamber drops;

. a third check valve connecting said second air storage chamber with said third cylinder whereby air may flow from said third cylinder into said second air storage chamber;

h. a fourth check valve opening into said second cylinder allowing air from the atmosphere to enter said second cylinder;

. a fuel injector opening into said first cylinder, said fuel injector operating in response to motion of said pistons; and,

j. a gas output conduit connected to said first cylinder.

4. A gas generator as in claim 2 and further including a water jacket surrounding said first cylinder, said water jacket communicating with said gas output conduit, whereby steam generated in said water jacket will flow out through said gas output conduit.

5. In a free piston combustion gas generator:

a. a recycling air storage chamber;

b. a cylinder connected to said recycling air storage chamber;

c. a piston slidable in said cylinder for recycling the generator, said piston being attached to the combustion cylinder piston of the generator said piston being positioned in said cylinder such that substantially all of the air from said cylinder is stored in said recycling air storage chamber during some portion of each gas generator cycle; and

d. a valve controlling the flow ,of recycling air from said storage chamber to said cylinder whereby recycling air will be brought to bear on said piston upon actuation of said valve.

6. The combination as recited in claim 5 wherein said valve is responsive to gas consumption.

7. A gas generator comprising:

a. a motor section, said motor section including a free piston;

b. a scavenging air pump coupled to said free piston; and,

c. a recycling section, said recycling section comprising:

i. a cylinder;

ii. a second piston slidable in said cylinder, said second piston and said cylinder defining a closed variable volume and said second piston being coupled to said free piston;

iii. an air storage chamber communicating with the variable volume defined by said cylinder and said second piston, said air storage chamber being proportioned with respect to said variable volume that substantially all of the air from said variable volume is stored in said air storage chamber during a portion of each gas generator cycle; and

iv. a valve controlling the flow of air between said air storage chamber and the variable volume defined by said cylinder and said second piston.

8. A gas generator as defined in claim 7 wherein said valve is responsive to the pressure of air pumped by said scavenging air pump.

9. A gas generator as defined in claim 8 wherein said scavenging air pump is a two stage pump.

10. A gas generator comprising:

. a. a motor section, said motor section including a first force summing means;

b. a scavenging air pump coupled to said first force summing means; and,

c. a recycling section, said recycling section comprising:

i. second force summing means coupled to said first force summing means;

an air storage chamber; lll. means for allowing air In said air storage chamber to communicate with said force summing means said air storage chamber and said force summing means being so proportioned that substantially all of the air bearing on said force summing means is stored in said air storage chamber during a portion of each gas generator cycle; and

iv. a valve controlling the flow of air between said air storage chamber and said force summing means.

11. A gas generator as in claim 10 wherein said valve is responsive to the pressure of air pumped by said scavenging air pump.

12. A gas generator comprising:

a. A combustion cylinder having inlet and exhaust ports;

b. means for introducing fuel into said combustion cylinder;

c. a first piston slidable within said combustion cylinder;

g. a second cylinder spaced from said combustion cylinder;

h. a second piston coupled to said first piston and positioned within said second cylinder;

i. a second air storage chamber adapted to store compressed air pumped by said second piston;

j. a second valve controlling the flow of air between said second storage chamber and said second piston, whereby actuation of said second valve allows compressed air from said second storage chamber to act on and move said second piston thereby causing said first piston to compress the gas in said combustion cylinder; and

k. means for actuating said second valve to start each gas generator cycle.

13. A gas generator as defined in claim 12 wherein said means for actuating said second valve is responsive to a drop in pressure in said first air storage chamber.

Claims

1. A gas generator comprising: a. A combustion cylinder having inlet and exhaust ports; b. means for introducing fuel into said combustion cylinder; c. a first piston slidable within said combustion cylinder; d. a scavenging air pump for supplying compressed air to said combustion cylinder; e. a first air storage chamber in communication with said scavenging air pump and with said combustion cylinder for storing the compressed air provided by said scavenging air pump; f. a first valve controlling the flow of air between said first air storage chamber and said combustion cylinder; g. a second cylinder spaced from said combustion cylinder; h. a second piston coupled to said first piston and positioned within said second cylinder: i. a second air storage chamber adapted to store air compressed by the motion of said second piston in said second cylinder whereby substantially all Of the air from said second cylinder is stored in said second air storage chamber during a portion of each cycle of operation; and j. a second valve controlling the flow of air between said second storage chamber and said second piston, whereby actuation of said second valve allows compressed air from said second storage chamber to act on and move said second piston thereby causing said first piston to compress the gas in said combustion cylinder.

3. A gas generator comprising: a. first, second and third concentric cylinders spaced axially; b. first, second and third pistons slidable within said first, second and third cylinders respectively, said pistons being coupled; c. a first air storage chamber; d. first and second check valves connecting said first and second cylinders respectively to said first air storage chamber, whereby air may flow from said second cylinder into said first air storage chamber, and from said first air storage chamber into said first cylinder; e. a second air storage chamber; f. a pressure responsive valve connecting said second air storage chamber with said third cylinder, said pressure responsive valve being responsive to the pressure in said first air storage chamber, whereby air in said second air storage chamber is allowed to flow into said third cylinder when pressure in said first air storage chamber drops; g. a third check valve connecting said second air storage chamber with said third cylinder whereby air may flow from said third cylinder into said second air storage chamber; h. a fourth check valve opening into said second cylinder allowing air from the atmosphere to enter said second cylinder; i. a fuel injector opening into said first cylinder, said fuel injector operating in response to motion of said pistons; and, j. a gas output conduit connected to said first cylinder.

5. In a free piston combustion gas generator: a. a recycling air storage chamber; b. a cylinder connected to said recycling air storage chamber; c. a piston slidable in said cylinder for recycling the generator, said piston being attached to the combustion cylinder piston of the generator said piston being positioned in said cylinder such that substantially all of the air from said cylinder is stored in said recycling air storage chamber during some portion of each gas generator cycle; and d. a valve controlling the flow of recycling air from said storage chamber to said cylinder whereby recycling air will be brought to bear on said piston upon actuation of said valve.

7. A gas generator comprising: a. a motor section, said motor section including a free piston; b. a scavenging air pump coupled to said free piston; and, c. a recycling section, said recycling section comprising: i. a cylinder; ii. a second piston slidable in said cylinder, said second piston and said cylinder defining a closed variable volume and said second piston being coupled to said free piston; iii. an air storage chamber communicating with the variable volume defined by said cylinder and said second piston, said air storage chamber being proportioned with respect to said variable volume that substantially all of the air from said variable volume is stored in said air storage chamber during a portion of each gas generator cycle; and iv. a valve controlling the flow of air between said air storage chamber and the variable volume defined by said cylinder and said second piston.

10. A gas generator comprising: a. a motor section, said motor section including a first force summing means; b. a scavenging air pump coupled to said first force summing means; and, c. a recycling section, said recycling section comprising: i. second force summing means coupled to said first force summing means; ii. an air storage chamber; iii. means for allowing air in said air storage chamber to communicate with said force summing means said air storage chamber and said force summing means being so proportioned that substantially all of the air bearing on said force summing means is stored in said air storage chamber during a portion of each gas generator cycle; and iv. a valve controlling the flow of air between said air storage chamber and said force summing means.

12. A gas generator comprising: a. A combustion cylinder having inlet and exhaust ports; b. means for introducing fuel into said combustion cylinder; c. a first piston slidable within said combustion cylinder; d. a scavenging air pump for supplying compressed air to said combustion cylinder; e. a first air storage chamber in communication with said scavenging air pump and with said combustion cylinder for storing the compressed air provided by said scavenging air pump; f. a first valve controlling the flow of air between said first air storage chamber and said combustion cylinder; g. a second cylinder spaced from said combustion cylinder; h. a second piston coupled to said first piston and positioned within said second cylinder; i. a second air storage chamber adapted to store compressed air pumped by said second piston; j. a second valve controlling the flow of air between said second storage chamber and said second piston, whereby actuation of said second valve allows compressed air from said second storage chamber to act on and move said second piston thereby causing said first piston to compress the gas in said combustion cylinder; and k. means for actuating said second valve to start each gas generator cycle.