Two-cycle, opposed-piston internal combustion engine

• US 20050274332A1
• Filed: 06/10/2004
• Published: 12/15/2005
• Est. Priority Date: 06/10/2004
• Status: Active Grant

• Current Assignee: Achates Power, Inc.
• Original Assignee: Achates Power, Inc.
• Inventors: Lemke, James U., McHargue, William B.
• Granted Patent: US 7,156,056 B2
• Time in Patent Office: Days
• US Class Current: 123/41.350
• CPC Class Codes: F01P 2003/005 the liquid being fuel
• CPC Class Codes: F01P 2003/006 the liquid being oil
• CPC Class Codes: F01P 2003/021 Cooling cylinders
• CPC Class Codes: F01P 2003/027 Cooling cylinders and cylinder heads in parallel
• CPC Class Codes: F01P 2003/028 Cooling cylinders and cylinder heads in series
• CPC Class Codes: F01P 3/06 Arrangements for cooling pistons
• CPC Class Codes: F02B 75/28 Engines with two or more pistons reciprocating within same cylinder or within essentially coaxial cylinders arranged oppositely relative to main shaft F02B75/24
• CPC Class Codes: F02B 75/282 the pistons having equal strokes
• CPC Class Codes: F02B 75/32 Engines characterised by connections between pistons and main shafts and not specific to preceding main groups
• CPC Class Codes: F02F 1/186 for use in engines with two or more pistons reciprocating within same cylinder
• CPC Class Codes: F16H 1/22 with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts

Abstract

In a two-cycle, opposed-piston internal combustion engine with optimized cooling and no engine block, the opposed pistons are coupled to a pair of crankshafts by connecting rods that are subject to substantially tensile forces acting between the pistons and the crankshafts.

Claims

1. An internal combustion engine, comprising:

a cylinder with an internal bore;

first and second opposed pistons adapted to reciprocate in the bore so as to protrude from the bore during at least a portion of an operating cycle of the engine; and

a supply system adapted to apply a liquid coolant to an external portion of each piston that protrudes from the bore.

2. The engine of claim 1, wherein the pistons each have an axial length and the external portion of each piston forms at least 25% of the of the axial length of the piston.

3. The engine of claim 1, wherein the pistons each have an axial length and the external portion of each piston forms at least 50% of the of the axial length of the piston.

4. The engine of claim 1, wherein the pistons each have an axial length and the external portion of each piston forms at least 75% of the of the axial length of the piston.

5. The engine of claim 1, wherein the liquid coolant comprises diesel fuel.

6. The engine of claim 1, wherein the liquid coolant comprises a lubricant.

7. The engine of claim 1, wherein the cylinder includes an exhaust manifold at a first end and an inlet manifold at a second end and the supply system includes dispensers outboard of the exhaust and intake manifolds.

8. The engine of claim 7, wherein the supply system further includes dispensers between the exhaust and intake manifolds.

9. The engine of claim 8, wherein the supply system further includes a low-pressure, high-volume pump to supply liquid coolant to the dispensers.

10. The engine of claim 7, wherein the engine includes roller bearings and the pump supplies lubricant for the bearings.

11. The engine of claim 1, wherein each piston has a crown and a skirt and wherein the external portion includes substantially all of the skirt.

12. The engine of claim 11, wherein the liquid coolant comprises a fuel.

13. The engine of claim 12, wherein the engine is a two-cycle compression-ignition engine and the fuel comprises diesel fuel.

14. The engine of claim 1, wherein the supply system is also adapted to apply the liquid coolant to the interior of each piston.

15. The engine of claim 14, wherein each piston is a hollow piston lacking a wristpin and having a crown, and wherein the supply system is also adapted to apply the liquid coolant to an interior surface of the crown of each piston.

16. The engine of claim 15, wherein the supply system includes dispensers aimed at the crowns of the pistons.

17. The engine of claim 16, wherein the pistons are ringless pistons.

18. The engine of claim 1, wherein the pistons are ringless pistons.

19. The engine of claim 18, wherein the cylinder has inlet and exhaust ports.

20. The engine of claim 19, wherein the cylinder lacks bridges spanning the ports.

21. The engine of claim 18, wherein the inlet and exhaust ports are formed from open annular galleries disposed adjacent opposite ends of the cylinder.

22. The engine of claim 1, wherein the supply system is also adapted to apply the liquid coolant to the cylinder.

23. The engine of claim 22, wherein the supply system comprises galleries which are configured to apply a coolant to the cylinder.

24. The engine of claim 1, wherein the cylinder does not constitute a structural component of the engine.

25. The engine of claim 1, further comprising:

first and second side-mounted crankshafts; and

rods which connect the pistons to the crankshafts.

26. The engine of claim 25, wherein the rods are subjected primarily to tensile forces during operation of the engine.

27. The engine of claim 25, wherein the cylinder has inlet and exhaust ports, and wherein the crankshafts, the rods, and the intake and exhaust ports are arranged such that the pistons are in phase in their top dead center positions and offset in phase in their bottom dead center positions.

28. The engine of claim 25, further comprising a frame adapted to support the crankshafts for rotation.

29. The engine of claim 28, wherein the frame supports compressive forces between the crankshafts.

30. The engine of claim 25, wherein the engine is a two-cycle compression-ignition engine.

31. The engine of claim 1, the cylinder including inlet and exhaust ports.

32. The engine of claim 31, the cylinder further including manifolds, wherein the inlet and exhaust ports open into respective manifolds, and each manifold has a shape that induces swirl.

33. The engine of claim 1, the cylinder including inlet and exhaust ports.

34. The engine of claim 1, wherein the engine operates at a power-to-weight ratio of at least 0.50 HP/lb.

35. The engine of claim 34, wherein the engine operates at a power-to-weight ratio of at least 0.67 HP/lb.

36. The engine of claim 35, wherein the engine operates at a power-to-weight ratio of at least 1.00 HP/lb.

37. A machine powered by the engine of claim 1.

38. A vehicle powered by the engine of claim 1.

39. The vehicle of claim 38, wherein the vehicle is a water craft.

40. The vehicle of claim 38, wherein the vehicle is an aircraft.

41. The vehicle of claim 38, wherein the vehicle is a surface vehicle.

42. A power tool powered by the engine of claim 1.

43. The engine of claim 1, further comprising first and second counter rotating crankshafts, the engine further including:

a first gear on the first crankshaft;

a second gear on the second crankshaft; and

,

a third gear supported on the frame, the third gear having an annulus with an outside circumference engaging the first gear at a first location and an inside circumference engaging the second gear at a second location opposite the first location.

44. An internal combustion engine, comprising:

a cylinder with an internal bore;

first and second opposed pistons adapted to reciprocate in the bore so as to be substantially withdrawn from the bore during at least a portion of an operating cycle;

each piston including crown and a skirt; and

a supply system adapted to apply a liquid coolant to an external portion of each piston that protrudes from the bore;

the external portion including substantially all of the skirt.

45. An internal combustion engine, comprising:

a cylinder with an internal bore;

wherein the cylinder does not constitute a structural component of the engine;

first and second opposed pistons adapted to reciprocate in the bore so as to be substantially withdrawn from the bore during at least a portion of an operating cycle; and

a supply system adapted to apply a liquid coolant to an external portion of each piston that protrudes from the bore.

46. An internal combustion engine, comprising:

a cylinder with an internal bore and two ends;

first and second opposed pistons adapted to reciprocate in the bore so as to be substantially withdrawn from the bore during at least a portion of an operating cycle; and

a supply system adapted to apply a liquid coolant to an external portion of each piston that protrudes from the bore;

the supply system including galleries outboard of the ends of the cylinder.

47. An internal combustion engine, comprising:

a cylinder with an internal bore;

first and second opposed pistons adapted to reciprocate in the bore so as to be substantially withdrawn from the bore during at least a portion of an operating cycle; and

means for applying a liquid coolant to an external portion of each piston that protrudes from the bore.

48. An internal combustion engine, including:

a frame;

a cylinder;

a pair of opposed pistons in the cylinder;

first and second side-mounted crankshafts supported for rotation on the frame and having axes in a common plane normal to the axis of the cylinder;

rods connecting each piston to the first crankshaft and to the second crankshaft; and

,

wherein the cylinder does not constitute a support component of the engine.

49. The engine of claim 48, further including:

a pair of ports in the cylinder adapted to conduct airflow through the cylinder; and

each piston adapted to modulate a respective port during engine operation.

50. The engine of claim 48, each piston adapted to be at least partially withdrawn from the cylinder to receive liquid coolant on its external surface during engine operation.

51. The engine of claim 50, further including dispensers disposed near the cylinder and adapted to apply the liquid coolant to portions of the external surfaces of the pistons outside of the cylinder.

52. The engine of claim 51, wherein the dispensers are disposed outboard of the cylinder.

53. The engine of claim 50, further including a plurality of dispensers disposed near each cylinder and adapted to apply a liquid coolant to portions of the external surfaces of pistons outside of the cylinder and to the external surface of the cylinder.

54. The engine of claim 53, further including a dispenser to apply a liquid coolant to the interior of each piston.

55. The engine of claim 54, further including means for supplying the liquid coolant to the dispensers.

56. The engine of claim 48, wherein the pistons are ringless.

57. The engine of claim 49, wherein the ports are continuously open galleries near ends of the cylinder and the pistons are ringless.

58. The engine of claim 49, further including at least one ring mounted to each piston.

59. The engine of claim 49, wherein the ports include at least one bridge.

60. The engine of claim 59, wherein the pistons are ringless.

61. The engine of claim 59, further including at least one ring mounted to each piston.

62. The engine of claim 48, characterized by an engine operation cycle in which each piston is withdrawn from a cylinder during a power stroke far enough to expose substantially the entire skirt region of the piston.

63. The engine of claim 48, wherein the crankshafts are adapted to rotate in opposite directions, the engine further including:

a first gear on the first crankshaft;

a second gear on the second crankshaft; and

,

a third gear supported on the frame, the third gear having an annulus with an outside circumference engaging the first gear at a first location and an inside circumference engaging the second gear at a second location opposite the first location.

64. An internal combustion engine, comprising:

at least one cylinder;

a pair of opposed pistons in the at least one cylinder;

a pair of side-mounted crankshafts;

a plurality of rods linking each piston to both crankshafts and adapted to move in response to primarily tensile forces acting between the pistons and the crankshafts;

the engine characterized by an engine cycle in which each piston is substantially withdrawn from the cylinder and then driven back into the cylinder; and

a system to apply a liquid coolant to the external surface of each piston that is withdrawn from the at least one cylinder.

65. The engine of claim 64, further including a frame adapted to support the crankshafts for rotation.

66. The engine of claim 64, the at least one cylinder including:

a radially symmetric tube with two ends;

a first manifold mounted to the tube at a first end;

a second manifold mounted to the tube at a second end;

an exhaust port in the first manifold;

an inlet port in the second manifold; and

at least one fuel injection element in the tube.

67. The engine of claim 66, the exhaust port including an annular gallery in the first manifold and the inlet port including an annular gallery in the second manifold.

68. The engine of claim 66, the system including first dispensers adapted to apply the liquid coolant to the external surfaces of the skirts of the pistons which are outside the cylinder during the engine cycle.

69. The engine of claim 68, further including second dispensers adapted to apply the liquid coolant to internal surfaces of the pistons.

70. The engine of claim 65, wherein the crankshafts are adapted to rotate in opposite directions, the engine further including:

a first gear on the first crankshaft;

a second gear on the second crankshaft; and

,

a third gear supported on the frame, the third gear having an annulus with an outside circumference engaging the first gear at a first location and an inside circumference engaging the second gear at a second location opposite the first location.

71. A combination for an internal combustion engine, including:

a radially symmetric cylinder;

a pair of opposed pistons disposed in the cylinder and adapted to be at least partially withdrawn from the cylinder to receive externally-applied liquid coolant during engine operation; and

a dispenser apparatus adapted to apply the liquid coolant to an external portion of each piston withdrawn from the cylinder.

72. The combination of claim 71, the cylinder including:

a tube with two ends;

a first manifold mounted to the tube at a first end;

a second manifold mounted to the tube at a second end;

an exhaust port in the first manifold;

an inlet port in the second manifold; and

,

a fuel injection element mounted to the tube.

73. The combination of claim 72, the exhaust port including an annular gallery in the first manifold and the inlet port including an annular gallery in the second manifold.

74. The combination of claim 73, wherein each gallery comprises a continuous annular opening.

75. The combination of claim 73, wherein each gallery includes one or more bridges.

76. The combination of claim 75, wherein the pistons are ringless.

77. The combination of claim 75, further including at least one ring mounted to each piston.

78. The combination of claim 71, further including dispensers adapted to apply coolant to the external surface of the cylinder.

79. The combination of claim 71, further including two ports adapted to provide airflow through the cylinder, each piston disposed against a port and having a length such that the port is opened by the piston being substantially withdrawn from the cylinder.

80. The combination of claim 79, further including:

a saddle mounted to the top of each piston;

a plurality of connecting rods; and

needle bearings coupling at least three connecting rods to each saddle.

81. A method for operating an internal combustion engine including at least one cylinder with at least two ports and a pair of opposed pistons disposed therein, including:

causing the pistons to be at least partially withdrawn from the at least one cylinder during engine operation; and

applying a liquid coolant to an external surface portion of each piston which is outside the cylinder.

82. The method of claim 81, further including applying the liquid coolant to an internal surface portion of each piston during engine operation.

83. The method of claim 82, further including applying the liquid coolant to the external surface of the cylinder.

84. The method of claim 83, wherein applying a liquid coolant to an external surface portion of each piston, applying a liquid coolant to an internal surface portion of each piston, and applying a liquid coolant to the external surface of the cylinder all comprise applying a fuel.

85. The method of claim 84, wherein the engine is a diesel engine and the fuel is diesel fuel.

86. A two-cycle, opposed piston, internal combustion engine, comprising:

at least one cylinder module, wherein the at least one cylinder module does not constitute a structural component of the engine;

a pair of opposed pistons in each cylinder module and adapted to be substantially withdrawn from the at least one cylinder module during engine operation;

each piston including a skirt and a crown;

each pair of pistons adapted to be coupled to the engine so as to exert no side force on a cylinder module during engine operation; and

means for applying a liquid coolant to an external portion of each piston that is substantially withdrawn from a cylinder module.

87. The engine of claim 86, the cylinder module comprising:

a tube with two open ends, a longitudinal center, and an outside surface;

a first manifold mounted to a first end of the tube;

a piston-modulated exhaust port in the first manifold;

a second manifold mounted to a second end of the tube;

a piston-modulated inlet port in the second manifold; and

a fuel injection element mounted to the tube near the longitudinal center.

88. The engine of claim 87, the means including dispensers adapted to apply the liquid coolant to the outside surface of the tube.

89. The engine of claim 86, the means including dispensers adapted to apply the liquid coolant to external surfaces of the skirts of the pistons outside of the cylinder module.

90. The engine of claim 89, the means further including dispensers adapted to apply the liquid coolant to inside surfaces of the crowns.

91. The engine of claim 86, wherein the pistons are ringless.

92. The engine of claim 91, the exhaust port and the inlet port having no bridges.

93. The engine of claim 88, further comprising:

a pair of side-mounted crankshafts; and

a least three rods linking each piston to the crankshafts to move the piston in response to substantially tensile forces between the piston and the respective crankshaft without exerting side force on a cylinder module.

94. The engine of claim 90, further comprising a frame to support the pair of crankshafts for rotation.

95. The engine of claim 94, wherein the crankshafts are adapted to rotate in opposite directions, the engine further including:

a first gear on the first crankshaft;

a second gear on the second crankshaft; and

,

a third gear supported on the frame, the third gear having an annulus with an outside circumference engaging the first gear at a first location and an inside circumference engaging the second gear at a second location opposite the first location.

96. A gear train for an internal combustion engine, comprising:

first and second gears adapted to be coupled to counter-rotating crankshafts; and

a third gear having an annulus with an outside circumference engaging the first gear at a first location and an inside circumference engaging the second gear at a second location opposite the first location.

97. An internal combustion engine, including:

a frame;

a cylinder;

a pair of opposed ringless pistons in the cylinder;

first and second side-mounted crankshafts supported for rotation on the frame and having axes in a common plane normal to the axis of the cylinder;

rods connecting each piston to the first crankshaft and to the second crankshaft; and

,

the cylinder adapted to be substantially radially symmetric along at least the entire length thereof during engine operation and not constituting a support component of the engine.

98. An internal combustion engine, comprising:

a cylinder with an internal bore;

first and second opposed pistons adapted to reciprocate in the bore so as to be substantially withdrawn from the bore during at least a portion of an operating cycle;

each piston including a skirt; and

a supply system adapted to provide a single liquid to cool an external portion of the skirt of each piston that protrudes from the bore, to lubricate the pistons, and to fuel the engine.

99. A method for operating an internal combustion engine having a cylinder with an internal bore, first and second opposed pistons adapted to reciprocate in the bore, and a system adapted to supply liquid coolant, the method comprising:

substantially withdrawing each piston from the bore during at least a portion of an operating cycle;

applying a liquid coolant to substantially all of an external surface of a skirt of each piston that protrudes from the bore; and

combusting fuel in the cylinder during the operating cycle to produce an engine brake mean effective pressure of at least 200 psi.

100. The method of claim 99, wherein combusting produces an engine brake mean effective pressure of at least 250 psi.

101. The method of claim 99, wherein combusting produces an engine brake mean effective pressure of at least 300 psi.

102. A method for operating an internal combustion engine having a cylinder with an internal bore, first and second opposed pistons adapted to reciprocate in the bore, and a system adapted to supply liquid coolant, the method comprising:

combusting fuel in the cylinder during an operating cycle of the engine to produce an engine brake mean effective pressure of at least 300 psi.

103. The method of claim 102, further comprising:

substantially withdrawing each piston from the bore during at least a portion of the operating cycle; and

applying a liquid coolant to substantially all of an external surface of a skirt of each piston that protrudes from the bore.

104. An internal combustion engine, comprising:

a cylinder with an internal bore;

first and second opposed pistons adapted to reciprocate in the bore so as to be substantially withdrawn from the bore during at least a portion of an operating cycle of the engine;

each piston including a skirt;

a supply system adapted to provide a liquid to cool substantially all of the external surface of the skirt of each piston that protrudes from the bore; and

a specific power density of at least 13.0 HP/in².

105. An internal combustion engine, comprising:

a cylinder with an internal bore;

first and second opposed pistons adapted to reciprocate in the bore so as to be substantially withdrawn from the bore during at least a portion of an operating cycle of the engine; and

a specific power density of at least 11.0 HP/in².

106. The internal combustion engine of claim 105, the engine having a specific power density of at least 12.0 HP/in².

107. The internal combustion engine of claim 105, the engine having a specific power density of at least 13.0 HP/in².

108. The internal combustion engine of claim 105, wherein each piston includes a skirt, and further comprising a supply system adapted to provide a liquid to cool substantially all of the external surface of the skirt of each piston that protrudes from the bore.

109. An internal combustion engine, comprising:

a cylinder with an internal bore;

first and second opposed pistons adapted to reciprocate in the bore so as to be substantially withdrawn from the bore during at least a portion of an operating cycle;

each piston including a skirt;

a supply system adapted to provide a liquid to cool substantially all of the external surface of the skirt of each piston that protrudes from the bore; and

a power to weight ratio of at least 1.0 HP/lb.

110. A gear train for an internal combustion engine, comprising:

first and second counter rotating gears adapted to be coupled to respective counter rotating crankshafts; and

an odd number of intermediate gears that are adapted to transfer torque from said crankshafts to a common output shaft without employing any intermediate torque transfer mechanisms.

111. The gear train of claim 110, wherein the odd number of intermediate gears comprise a single gear having an annulus with an outside circumference engaging the first gear at a first location and an inside circumference engaging the second gear at a second location opposite the first location.

112. An internal combustion engine, comprising:

a cylinder with an internal bore;

first and second opposed pistons adapted to reciprocate in the bore;

first and second side mounted crankshafts;

connectors connecting the pistons to the crankshafts;

roller bearings supporting the crankshafts and coupling points of the connectors to the pistons and the crankshafts; and

a supply system adapted to apply a liquid to the bearings to lubricate the bearings.

113. The internal combustion engine of claim 112, wherein the pistons adapted to protrude from the bore during at least a portion of an operating cycle of the engine, and wherein the supply system is adapted to apply the liquid to an external portion of each piston that protrudes from the bore to cool the piston.

114. The internal combustion engine of claim 113, wherein the engine is a compression ignition engine and the liquid is diesel fuel.

115. An internal combustion engine that is cooled, fueled and lubricated by a common liquid.

116. The internal combustion engine of claim 115, including a single source of the common liquid.

117. A method comprising cooling, fueling and lubricating an internal combustion engine with a common liquid.

118. The method of claim 117, further including obtaining the common liquid from a single source.