LINEAR FREE PISTON COMBUSTION ENGINE WITH INDIRECT WORK EXTRACTION VIA GAS LINKAGE

• US 20120204836A1
• Filed: 02/15/2011
• Published: 08/16/2012
• Est. Priority Date: 02/15/2011
• Status: Active Grant

• Current Assignee: Mainspring Energy, Inc.
• Original Assignee: Etagen, Inc.
• Inventors: Roelle, Matthew J., Simpson, Adam P.
• Granted Patent: US 8,997,699 B2
• Time in Patent Office: Days
• US Class Current: 123/46.R
• CPC Class Codes: F02B 71/04 Adaptations of such engines for special use; Combinations of such engines with apparatus driven thereby
• CPC Class Codes: F02B 75/285 comprising a free auxiliary piston

Abstract

Various embodiments of the present invention are directed toward a linear free piston combustion engine with indirect work extraction via gas linkage, comprising: a cylinder with two opposed free pistons disposed therein that form a combustion section in a center of the cylinder, each free piston comprising a front face facing the combustion section and a back face facing the opposite direction: two opposed extractor pistons disposed in their own cylinders at opposite ends of the free piston cylinder, each extractor piston comprising a front face facing the combustion section and a back face facing the opposite direction; and two gas linkages, each gas linkage comprising a volume sealed between the back face of a free piston and the front face of an extractor piston; wherein each extractor piston is connected to a rotary electromagnetic machine.

Claims

1. A linear free piston combustion engine with indirect work extraction via gas linkage, comprising:

a cylinder with two opposed free pistons disposed therein that form a combustion section in a center of the cylinder, each free piston comprising a front face facing the combustion section and a back face facing the opposite direction;

two opposed extractor pistons disposed in their own cylinders at opposite ends of the free piston cylinder, each extractor piston comprising a front face facing the combustion section and a back face facing the opposite direction; and

two gas linkages, each gas linkage comprising a volume sealed between the back face of a free piston and the front face of an extractor piston;

wherein each extractor piston is connected to a rotary electromagnetic machine.

2. The engine of claim 1, wherein the gas linkage acts a gas spring translating forces between two moving pistons without dictating a specific axial separation or a specific volumetric separation.

3. The engine of claim 1, wherein the force on the front face of an extractor piston is directly converted into rotary motion, which is then converted to electrical energy through the rotary electromagnetic machine.

4. The engine of claim 1, wherein the rotary electromagnetic machine comprises a permanent magnet machine, induction machine, switched reluctance machine, or a combination thereof.

5. The engine of claim 1, further comprising a device for directly or indirectly applying a force to the free pistons in order to adjust piston velocity and phasing to selected values.

6. The engine of claim 1, wherein the engine operates using a two-stroke piston cycle including a power stroke and a compression stroke, with an expansion ratio greater than a compression ratio, wherein combustion occurs after the compression stroke when the velocities of the free pistons are at or near zero.

7. The engine of claim 1, wherein the engine operates using a four-stroke piston cycle including a power stroke, an exhaust stroke, an intake stroke, and a compression stroke, with an expansion ratio greater the compression ratio, wherein combustion occurs after a compression stroke when the velocities of the free pistons are at or near zero.

8. The engine of claim 1, wherein:

fuel is directly injected into the combustion section via fuel injectors or is mixed with air prior to or during air intake; and

the engine is capable of operation with lean, stoichiometric, or rich combustion using liquid or gaseous fuels.

9. The engine of claim 1, further comprising:

one or more exhaust/injector ports that allow exhaust gases and fluids to enter and leave the free piston cylinder;

one or more intake ports that allow the intake of air or air/fuel mixtures or air/fuel/combustion product mixtures;

one or more driver gas removal ports that allow for the removal of driver gas; and

one or more driver gas make-up ports that allow for the intake of make-up gas for the driver section.

10. The engine in claim 1, wherein combustion products from a previous cycle can be mixed with intake air and/or an intake air/fuel mixture prior to or during a compression stroke.

11. The engine of claim 1, wherein:

engine ignition is achieved via compression ignition; and

optimal combustion is achieved by moderating the gas temperature such that it auto ignites at its optimal volume.

12. The engine of claim 1, wherein:

engine ignition is achieved via spark ignition; and

optimal combustion is achieved by moderating the gas temperature such that it does not auto-ignite before a spark fires at its optimal volume.

13. A free piston combustion engine with indirect work extraction via gas linkage, comprising:

a cylinder with curved ends with two opposed free pistons disposed therein that form a combustion section in a center of the cylinder, each free piston comprising a front face facing the combustion section and a back face facing the opposite direction;

two opposed extractor pistons, each extractor piston disposed in its own cylinder at opposite ends of the free piston cylinder, each extractor piston comprising a front face facing the combustion section and a back face facing the opposite direction; and

two gas linkages, each gas linkage comprising a volume sealed between the hack face of a free piston and the front face of an extractor piston;

wherein each extractor piston is connected to a single rotary electromagnetic machine.

14. The engine of claim 13, wherein the gas linkage acts a gas spring translating forces between two moving pistons without dictating a specific axial separation or a specific volumetric separation.

15. The engine of claim 13, wherein the force on the front face of an extractor piston is directly converted into rotary motion, which is then converted to electrical energy through the rotary electromagnetic machine.

16. The engine of claim 13, wherein the rotary electromagnetic machine comprises a permanent magnet machine, induction machine, switched reluctance machine, or a combination thereof.

17. The engine of claim 13, further comprising a device for directly or indirectly applying a force to the free pistons in order to adjust piston velocity and phasing to selected values.

18. The engine of claim 13, wherein the engine operates using a two-stroke piston cycle including a power stroke and a compression stroke, with an expansion ratio greater than a compression ratio, wherein combustion occurs after the compression stroke when the velocities of the free pistons arc at or near zero.

19. The engine of claim 13, wherein the engine operates using a four-stroke piston cycle including a power stroke, an exhaust stroke, an intake stroke, and a compression stroke, with an expansion ratio greater the compression ratio, wherein combustion occurs after a compression stroke when the velocities of the free pistons are at or near zero.

20. The engine of claim 13, wherein:

fuel is directly injected into the combustion section via fuel injectors or is mixed with air prior to or during air intake; and

the engine is capable of operation with lean, stoichiometric, or rich combustion using liquid or gaseous fuels.

21. The engine of claim 13, further comprising:

one or more exhaust/injector ports that allow exhaust gases and fluids to enter and leave the free piston cylinder;

one or more intake ports that allow the intake of air or air/fuel mixtures or air/fuel/combustion product mixtures;

one or more driver gas removal ports that allow for the removal of driver gas; and

one or more driver gas make-up ports that allow for the intake of make-up gas for the driver section.

22. The engine in claim 13, wherein combustion products from a previous cycle can be mixed with intake air and/or an intake air/fuel mixture prior to or during a compression stroke.

23. The engine of claim 13, wherein:

engine ignition is achieved via compression ignition; and

optimal combustion is achieved by moderating the gas temperature such that it auto ignites at its optimal volume.

24. The engine of claim 13, wherein:

engine ignition is achieved via spark ignition; and

optimal combustion is achieved by moderating the gas temperature such that it does not auto-ignite before a spark fires at its optimal volume.

25. A linear free piston combustion engine with indirect work extraction via gas linkage, comprising:

a cylinder with two opposed free pistons disposed therein that form a combustion section in a center of the cylinder, each free piston comprising a front face facing the combustion section and a back face facing the opposite direction;

two opposed extractor pistons disposed in their own cylinders at opposite ends of the free piston cylinder, each extractor piston comprising a front face facing the combustion section and a back face facing the opposite direction; and

two gas linkages, each gas linkage comprising a volume sealed between the back face of a free piston and the front face of an extractor piston;

wherein each extractor piston is connected to a linear electromagnetic machine that convert kinetic energy of the extractor piston to electrical energy.

26. The engine of claim 25, wherein the linear electromagnetic machine comprises a stator and a translator.

27. The engine of claim 26, wherein the extractor piston includes a piston rod that is attached to the translator.

28. The engine of claim 25, wherein the linear electromagnetic machine is configured to directly convert kinetic energy of extractor piston into electrical energy during an expansion stroke.

29. The engine of claim 25, wherein the linear electromagnetic machine comprises a permanent magnet machine, induction machine, switched reluctance machine, or a combination thereof.

30. The engine of claim 25, wherein the force on the front face of an extractor piston is directly converted into rotary motion, which is then converted to electrical energy through the rotary electromagnetic machine.

31. The engine of claim 25, wherein the gas linkage acts a gas spring translating forces between two moving pistons without dictating a specific axial separation or a specific volumetric separation.

32. The engine of claim 25, further comprising a device for directly or indirectly applying a force to the free pistons in order to adjust piston velocity and phasing to selected values.

33. The engine of claim 25, wherein the engine operates using a two-stroke piston cycle including a power stroke and a compression stroke, with an expansion ratio greater than a compression ratio, wherein combustion occurs after the compression stroke when the velocities of the free pistons are at or near zero.

34. The engine of claim 25, wherein the engine operates using a four-stroke piston cycle including a power stroke, an exhaust stroke, an intake stroke, and a compression stroke, with an expansion ratio greater the compression ratio, wherein combustion occurs after a compression stroke when the velocities of the free pistons are at or near zero.

35. The engine of claim 25, wherein:

fuel is directly injected into the combustion section via fuel injectors or is mixed with air prior to or during air intake; and

the engine is capable of operation with lean, stoichiometric, or rich combustion using liquid or gaseous fuels.

36. The engine of claim 25, further comprising:

one or more exhaust/injector ports that allow exhaust gases and fluids to enter and leave the free piston cylinder;

one or more intake ports that allow the intake of air or air/fuel mixtures or air/fuel/combustion product mixtures;

one or more driver gas removal ports that allow for the removal of driver gas; and

one or more driver gas make-up ports that allow for the intake of make-up gas for the driver section.

37. The engine in claim 25, wherein combustion products from a previous cycle can be mixed with intake air and/or an intake air/fuel mixture prior to or during a compression stroke.

38. The engine of claim 25, wherein:

engine ignition is achieved via compression ignition; and

optimal combustion is achieved by moderating the gas temperature such that it auto ignites at its optimal volume.

39. The engine of claim 25, wherein:

engine ignition is achieved via spark ignition; and

optimal combustion is achieved by moderating the gas temperature such that it does not auto-ignite before a spark fires at its optimal volume.

40. A linear free piston combustion engine with indirect work extraction via gas linkage, comprising:

a cylinder having a combustion section located at a closed end of the cylinder;

a free piston disposed within the cylinder, the free piston comprising a front face facing the combustion section and a back face facing the opposite direction;

an extractor piston disposed in its own cylinder at an end of the cylinder opposite the closed end, the extractor piston comprising a front face facing the combustion section and a back face facing the opposite direction; and

a gas linkage comprising a volume sealed between the back face of the free piston and the front face of the extractor piston;

wherein the extractor piston is connected to a rotary electromagnetic machine.

41. The engine of claim 40, wherein the force on the front face of the extractor piston is directly converted into rotary motion, which is then converted to electrical energy through the rotary electromagnetic machine.

42. The engine of claim 40, wherein the rotary electromagnetic machine comprises a permanent magnet machine, induction machine, switched reluctance machine, or a combination thereof.

43. The engine of claim 40, wherein the engine operates using a four-stroke piston cycle including a power stroke, an exhaust stroke, an intake stroke, and a compression stroke.

44. The engine of claim 40, wherein the force on the front face of an extractor piston is directly converted into rotary motion, which is then converted to electrical energy through the rotary electromagnetic machine.

45. The engine of claim 40, wherein the rotary electromagnetic machine comprises a permanent magnet machine, induction machine, switched reluctance machine, or a combination thereof.

46. The engine of claim 40, wherein the gas linkage acts a gas spring translating forces between two moving pistons without dictating a specific axial separation or a specific volumetric separation.

47. The engine of claim 40, further comprising a device for directly or indirectly applying a force to the free pistons in order to adjust piston velocity and phasing to selected values.

48. The engine of claim 40, wherein the engine operates using a two-stroke piston cycle including a power stroke and a compression stroke, with an expansion ratio greater than a compression ratio, wherein combustion occurs after the compression stroke when the velocities of the free pistons are at or near zero.

49. The engine of claim 40, wherein the engine operates using a four-stroke piston cycle including a power stroke, an exhaust stroke, an intake stroke, and a compression stroke, with an expansion ratio greater the compression ratio, wherein combustion occurs after a compression stroke when the velocities of the free pistons are at or near zero.

50. The engine of claim 40, wherein:

fuel is directly injected into the combustion section via fuel injectors or is mixed with air prior to or during air intake; and

the engine is capable of operation with lean, stoichiometric, or rich combustion using liquid or gaseous fuels.

51. The engine of claim 40, further comprising:

one or more exhaust/injector ports that allow exhaust gases and fluids to enter and leave the free piston cylinder;

one or more intake ports that allow the intake of air or air/fuel mixtures or air/fuel/combustion product mixtures;

one or more driver gas removal ports that allow for the removal of driver gas; and

one or more driver gas make-up ports that allow for the intake of make-up gas for the driver section.

52. The engine in claim 40, wherein combustion products from a previous cycle can be mixed with intake air and/or an intake air/fuel mixture prior to or during a compression stroke.

53. The engine of claim 40, wherein:

engine ignition is achieved via compression ignition; and

optimal combustion is achieved by moderating the gas temperature such that it auto ignites at its optimal volume.

54. The engine of claim 40, wherein:

engine ignition is achieved via spark ignition; and

optimal combustion is achieved by moderating the gas temperature such that it does not auto-ignite before a spark fires at its optimal volume.

55. A linear free piston combustion engine with indirect work extraction via gas linkage, comprising:

a cylinder having a combustion section located at a closed end of the cylinder;

a free piston disposed within the cylinder, the free piston comprising a front face facing the combustion section and a back face facing the opposite direction;

an extractor piston disposed in its own cylinder at an end of the cylinder opposite the closed end, the extractor piston comprising a front face facing the combustion section and a back face facing the opposite direction; and

a gas linkage comprising a volume sealed between the back face of the free piston and the front face of the extractor piston;

wherein the extractor piston is connected to a linear electromagnetic machine.

56. The engine of claim 55, wherein the linear electromagnetic machine comprises a stator and a translator.

57. The engine of claim 56, wherein the extractor piston includes a piston rod that is attached to the translator.

58. The engine of claim 55, wherein the linear electromagnetic machine is configured to directly convert electrical energy into kinetic energy of the piston assembly for providing compression work during a compression stroke.

59. The engine of claim 55, wherein the linear electromagnetic machine comprises a permanent magnet machine, induction machine, switched reluctance machine, or a combination thereof.

60. The engine of claim 55, wherein the force on the front face of an extractor piston is directly converted into rotary motion, which is then converted to electrical energy through the rotary electromagnetic machine.

61. The engine of claim 55, wherein the gas linkage acts a gas spring translating forces between two moving pistons without dictating a specific axial separation or a specific volumetric separation.

62. The engine of claim 55, further comprising a device for directly or indirectly applying a force to the free pistons in order to adjust piston velocity and phasing to selected values.

63. The engine of claim 55, wherein the engine operates using a two-stroke piston cycle including a power stroke and a compression stroke, with an expansion ratio greater than a compression ratio, wherein combustion occurs after the compression stroke when the velocities of the free pistons are at or near zero.

64. The engine of claim 55, wherein the engine operates using a four-stroke piston cycle including a power stroke, an exhaust stroke, an intake stroke, and a compression stroke, with an expansion ratio greater the compression ratio, wherein combustion occurs after a compression stroke when the velocities of the free pistons are at or near zero.

65. The engine of claim 55, wherein:

fuel is directly injected into the combustion section via fuel injectors or is mixed with air prior to or during air intake; and

the engine is capable of operation with lean, stoichiometric, or rich combustion using liquid or gaseous fuels.

66. The engine of claim 55, further comprising:

one or more exhaust/injector ports that allow exhaust gases and fluids to enter and leave the free piston cylinder;

one or more intake ports that allow the intake of air or air/fuel mixtures or air/fuel/combustion product mixtures;

one or more driver gas removal ports that allow for the removal of driver gas; and

one or more driver gas make-up ports that allow for the intake of make-up gas for the driver section.

67. The engine in claim 55, wherein combustion products from a previous cycle can be mixed with intake air and/or an intake air/fuel mixture prior to or during a compression stroke.

68. The engine of claim 55, wherein:

engine ignition is achieved via compression ignition; and

optimal combustion is achieved by moderating the gas temperature such that it auto ignites at its optimal volume.

69. The engine of claim 55, wherein:

engine ignition is achieved via spark ignition; and

optimal combustion is achieved by moderating the gas temperature such that it does not auto-ignite before a spark fires at its optimal volume.