Two plus two stroke opposed piston heat engine

• US 4,996,953 A
• Filed: 04/02/1990
• Issued: 03/05/1991
• Est. Priority Date: 04/02/1990
• Status: Expired due to Fees

• Current Assignee: Erik S. Buck
• Original Assignee: Erik S. Buck
• Inventors: Buck, Erik S.
• Primary Examiner(s): Wolfe, Willis R.
• Assistant Examiner(s): Moulis, Thomas N.
• Application Number:
  US07/503,406
• Time in Patent Office: 337 Days
• Field of Search: 123/58 AM, 123/58 AB, 123/58 BC, 123/51 A, 123/51 B, 123/51 BD, 123/48 D, 123/48 A, 123/48 AA, 123/78 R, 123/78 D, 123/254, 123/255, 123/268, 123/292
• US Class Current: 123/51.00A
• CPC Class Codes: F01B 3/0035 having two or more sets of cylinders or pistons
• CPC Class Codes: F01B 3/045 by two or more curved surfaces, e.g. for two or more pistons in one cylinder
• CPC Class Codes: F02B 1/04 with fuel-air mixture admission into cylinder
• CPC Class Codes: F02B 2075/025 two
• CPC Class Codes: F02B 2075/027 four
• CPC Class Codes: F02B 2075/028 five
• CPC Class Codes: F02B 2075/125 Direct injection in the combustion chamber for spark ignition engines, i.e. not in pre-combustion chamber
• CPC Class Codes: F02B 2275/36 Modified dwell of piston in TDC
• CPC Class Codes: F02B 3/06 with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: F02B 75/26 Engines with cylinder axes coaxial with, or parallel or inclined to, main-shaft axis; Engines with cylinder axes arranged substantially tangentially to a circle centred on main-shaft axis
• CPC Class Codes: F02B 75/282 the pistons having equal strokes
• CPC Class Codes: F02F 2007/0092 Transparent materials
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

Combustion engines have opposed pistons in one or more cylinders, with the piston motion determined by cams. Ports, for intake and exhaust, are at one end of the cylinder, opened or closed by one piston, with the combustion chamber at the other end, and the engine being well suited to the optional use of a combustion chamber separate from the cylinder and with the communicating passages controlled by the other piston. That arrangement makes the engine particularly suitable for using heavy or unconventional fuels. The cam profile provides for a four-stroke cycle; one piston moves during the intake and exhaust strokes, while the second piston moves for compression and power strokes. Thus the advantages of a four-stroke engine are obtained while retaining the simplicity of a two-stroke engine. The cam profile may be tailored to the burning characteristics of the fuel, as by providing a period of dwell between the end of the compression stroke and the beginning of the power stroke. The engine is well suited to the use of compression ignition, but spark ignition is feasible. The isolated combustion chamber may also be replaced by a heat exchanger, to use an external heat source.

Claims

1. An engine, comprising at least one cylinder, a pair of opposed pistons in said cylinder including a power piston and an intake piston and defining a variable space therebetween,

means interconnecting said pistons to convert axial movement of said pistons in said cylinder into rotary motion,

means for delivering combustion fuel into said space between said pistons,

means in said cylinder defining an exhaust port and an air intake port,

said ports being positioned in said cylinder so that they are covered and uncovered by said power piston,

said intake piston being movable from a retracted position spaced from said power piston providing for the entrance of fuel into said space to an extended position in proximity to said air intake and exhaust ports,

said power piston being movable between a retracted position in which said air intake and exhaust ports are uncovered to an extended position toward said intake piston in proximity to intake piston,

said rotary connecting means causing said intake piston to move in a cycle from said extended position toward said retracted position, and causing said power piston to move from its said retracted position toward said intake piston to compress and heat gasses trapped therebetween, and causing said intake piston to move to said retracted position,

said power piston being movable in a power stroke toward said retracted position until said exhaust port is uncovered for exhaust of burnt gasses from within said cylinder,

said rotary connecting means then causing intake piston to move from its retracted toward said power piston onto purge the cylinder of burnt fuel.

2. The engine of claim 1 in which said means for delivering combustion fuel into said cylinder includes a combustion chamber external to said cylinder, and a combustion fuel inlet port in said cylinder wall connecting said combustion chamber to said cylinder.

3. The engine of claim 1 in which said means for delivering combustion fuel into said cylinder includes a carburetor and gas conduit means connecting said carburetor to said cylinder.

4. The engine of claim 1 in which said means for delivering combustion fuel into said cylinder includes a fuel injector positioned on said cylinder to inject fuel into said space between said pistons.

5. In a heat engine suitable for multiple fuel operation, having a cylinder, first and second opposed pistons in said cylinder including a power piston and an intake piston, and cam means interconnecting said pistons to convert axial movement of said pistons in said cylinder into rotary motion, the improvement comprising:

an external combustion chamber,

one-way fuel valve means for admitting fuel from a source of fuel into said chamber,

a fuel inlet port leading from said chamber and opening into said cylinder so it is covered and uncovered by axial movement of said intake piston,

means in said cylinder defining an exhaust port and an air intake port spaced from fuel inlet port and located so that they are covered and uncovered by said power piston,

said intake piston being movable from a retracted position in which said fuel inlet port is uncovered to an extended position in proximity to said air intake and exhaust ports,

said power piston being movable between a retracted position in which said air intake and exhaust ports are uncovered to an extended position toward said intake piston in proximity to said fuel inlet port,

said rotary connecting means causing said intake piston to move in a cycle from said extended position toward said retracted position, and causing said power piston to move from its said retracted position toward said intake piston to compress and heat gasses trapped therebetween, and causing said intake piston to move to said retracted position so as to uncover said fuel inlet port and admit said hot compressed gasses into said external chamber for combustion of said fuel,

said power piston being movable in a power stroke toward said retracted position until said exhaust port is uncovered for exhaust of burnt gasses from within said cylinder, said rotary connecting means then causing intake piston to move from its retracted position to recover said inlet port toward said power piston to purge the cylinder of burnt fuel.

6. The engine of claim 5 in which fuel is admitted into said chamber only during times when said inlet port is covered by said intake piston.

7. The engine of claim 5 in which said interconnecting means causes said intake piston to pause while said power piston is moving, and said power piston is caused to pause while said intake piston is moving.

8. The engine of claim 5 further comprising cam means for delaying the opening of said inlet port by said intake piston until the air between said pistons is compressed in said compression stroke.

9. The engine of claim 5 further comprising means for adding heat energy to said external chamber.

10. The engine of claim 5 further comprising means for varying the volume of said external chamber.

11. The engine of claim 5 further comprising duct means in said power piston communicating with said exhaust and intake ports in the retracted position thereof and opening into the interior of said cylinder between said pistons.

12. In an opposed piston engine including at least one cylinder and a pair of opposed pistons in said cylinder to compress a working gas and provide a power stroke with means for converting the movement of the pistons into useful rotary motion, the improvement comprising:

means in a wall of said cylinder defining an intake port and an exhaust port,

one of said pistons being movable in a compression stroke to accomplish compression of the working gas in the space between said pistons, and in a power stroke providing form the expansion of said gasses, and being movable with respect to said outlet and intake ports for selectively covering and uncovering said ports for exhaust of burnt fuel through said outlet port and for the admission of combustion air through said intake port,

the other said piston being moveable with respect to said one piston in an intake stroke away from said one piston and an exhaust stroke toward said one piston,

means for delivering fuel into said cylinder during said intake stroke,

and means for igniting said fuel during said compression stroke.

13. The engine of claim 12 in which said pistons operate in a four-stroke cycle.

14. The engine of claim 12 in which said means for admitting fuel includes a combustion chamber external to said cylinder, a combustion chamber port opening into said cylinder, and one-way fuel inlet valve means connected to admit fuel under relatively low pressure into the interior of said external chamber.

15. The engine of claim 14 further comprising means for varying the volume of said chamber.

16. The engine of claim 14 in which said chamber contains a catalyst.

17. The engine of claim 14 in which said combustion chamber port is uncovered by said one piston after gasses between said piston pair has been heated by compression by movement of said other piston toward said one piston.

18. The engine of claim 12 in which said cylinder is a first cylinder, and a second said cylinder positioned alongside said first cylinder and having a pair of pistons therein identical to the pistons in said first cylinder and reversed in relative position, a first cam means connected to operate the intake piston of said first cylinder and the power piston of said second cylinder, and a second complimentary cam connected to operate the power piston of said first cylinder and the intake piston of said second piston.

19. An improved cam-operated barrel type engine in which a plurality of generally axially extending cylinders are arranged in angularly spaced relation and each have pair of opposed pistons which are operated by drive cams common to all of said cylinders, the improvement comprising a separate external combustion chamber for each of said cylinders, port means connected each said chamber to its associated said cylinder, fuel inlet means for admitting fuel into the interior of each said chamber, said fuel inlet means effective to admit said fuel when the pressure in the associated said chamber is lower than the fuel pressure, and valve means for preventing fuel or vapor flow out of a said chamber and into a fuel supply line.

20. The method of operating a heat engine having a pair of opposed pistons in a common cylinder, in which said opposed pistons are caused to operate in a cycle of operation including at least an intake, a compression, a power and an exhaust stroke, and in which an external combustion chamber communicates with said cylinder through a port controlled by one of said pistons, comprising the steps of admitting fuel to be burned into said external chamber while said port is covered by said one piston, and causing gasses trapped between said pistons to be compressed and heated to a combustion temperature by relative movement of the other piston in the cylinder toward said first piston prior to the opening of said port by said first piston, and causing said first piston to open said port to admit the highly compressed and heated gasses into said chamber for combustion.

21. The method of claim 20 further comprising the step of moving the first piston during combustion in a direction to yield an expansion ratio greater than the compression ratio.

22. The method of claim 20 including the further step of causing the first piston to pause in its cycle of operation with the inlet port open to provide an extended time for the heat to be communicated to said chamber.

23. The method of claim 20 including the further step of supplying heat to said chamber from a source of heat external to said cylinder.

24. The method of claim 23 including the step of supplying fuel to said chamber under pressure, and in which the quantity of fuel admitted into said chamber is dependent upon said fuel pressure.

25. The method of claim 20 including the step of delaying the opening of said external combustion chamber port to said one piston until the gas between said pistons is substantially compressed by a compression stroke of said second piston.

26. The method of operating a heat engine having a pair of opposed pistons in a common cylinder, in which said opposed pistons are caused to operate in a cycle of operation including at least a compression, a power and an exhaust and an intake stroke, and in which an external combustion chamber communicates with said cylinder through a port controlled by one of said pistons, comprising the steps of admitting fuel to be burned into said external chamber during said intake stroke, causing gasses trapped between said pistons to be compressed and heated to a combustion temperature by relative movement of the other piston in the cylinder toward said first piston during said compression stroke, and moving said first piston relative to said port during said compression stroke to admit compressed and heated gasses into said chamber for combustion, maintaining said port open during said power stroke.

27. The method of claim 26 in which fuel applied to said chamber from a fuel supply line of relatively constant pressure through a check valve, and in which fuel is admitted from said line into said chamber when the pressure in said chamber is less than the pressure of the fuel in said supply line.

28. The method of operating an opposed piston fuel burning engine in which a combustion cylinder has an opposed pair of pistons defining an intake piston and a power piston, in which the movements of the pistons are controlled by profiled cams, and the cylinder has intake and exhaust ports controlled the movement of the power piston and including a means for admitting fuel into the space between the pistons for combustion and expansion, comprising the steps of causing the intake piston to move in an intake stroke away from the power piston during the time that the power piston has uncovered an intake port and causing air to be drawn into the cylinder, causing the power piston to move toward the intake piston to close the intake and exhaust ports in a compression stroke, causing fuel to be admitted into the space between the pistons to form a fuel/air mixture in the cylinder for combustion, causing combustion of such mixture at or near the end of said compression stroke, causing said power piston to move away from said intake piston in a power stroke to open at least said exhaust port, and causing said intake piston to move toward said power piston to purge the space therebetween of burnt fuel gasses.

29. The method of claim 28 further including the step of moving said intake piston away from said power piston during said power stroke to effect an expansion of the compression ratio of the engine.

30. The method of claim 28 in which said exhaust port is opening during said power stroke before the intake port is opened.

31. The method of claim 28 in which the cylinder is formed with a fuel inlet port controlled by the movement of said intake piston, and which said inlet port is caused to be opened by said intake piston during said intake stroke thereof.