Opposed piston, homogeneous charge pilot ignition engine

• US 20060219213A1
• Filed: 03/31/2005
• Published: 10/05/2006
• Est. Priority Date: 03/31/2005
• Status: Active Grant

• Current Assignee: Achates Power, Inc.
• Original Assignee: Achates Power, Inc.
• Inventors: Lemke, James U.
• Granted Patent: US 7,270,108 B2
• Time in Patent Office: Days
• US Class Current: 123/299
• CPC Class Codes: F01B 7/14 acting on different main shafts
• CPC Class Codes: F02B 1/12 with compression ignition with fuel-air charge ignited by compression ignition of an additional fuel F02B7/00
• CPC Class Codes: F02B 2075/025 two
• CPC Class Codes: F02B 2275/14 Direct injection into combustion chamber
• CPC Class Codes: F02B 25/08 Engines with oppositely-moving reciprocating working pistons
• 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 7/02 the fuel in the charge being liquid
• CPC Class Codes: F02B 75/282 the pistons having equal strokes
• CPC Class Codes: F02D 41/3047 said means being a secondary injection of fuel
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

An engine of the opposed piston, two-stroke, compression ignition type includes provision for injection of a main charge of liquid fuel into the bore of a cylinder between opposed pistons early in a compression stroke to permit the fuel to evaporate and mix with air during the remainder of the compression stroke to the point where the stoichiometric components of the mixture are insufficient for autoignition. Further provision is made for injection of a pilot charge of liquid fuel into the compressed air/fuel mixture later in the compression stroke. The pilot charge provides a stoichiometric component which autoignites, thereby activating ignition of the compressed air/fuel mixture.

Claims

1. A method of operating an opposed piston compression ignition engine including a cylinder, a pair of opposed pistons in the bore of the cylinder and spaced-apart inlet and exhaust ports controlled by the pistons, comprising:

introducing air into the cylinder between the pistons;

moving the pistons toward each other;

injecting a lean main charge of liquid fuel into the cylinder between the pistons through at least one main injection site on the cylinder between the inlet port and the exhaust port;

in response to movement of the pistons, the main charge fully evaporating before an autoignition temperature is reached; and

then

injecting a pilot charge of liquid fuel through at least one pilot injection site;

the pilot charge igniting the evaporated main charge.

2. The method of claim 1, wherein the mass of the pilot charge is less than the mass of the main charge required to idle the engine.

3. The method of claim 2, further including modulating the mass of the main charge in response to at least one engine operating condition.

4. The method of claim 1, wherein injecting a main charge includes injecting a first portion of the main charge through a main injection site on the cylinder near the inlet port and injecting a second portion of the main charge through a main injection site on the cylinder near the exhaust port.

5. The method of claim 4, wherein the pistons cover the main injection sites while moving toward each other.

6. The method of claim 1, wherein injecting a main charge includes injecting a first portion of the main charge through a main injection site on the cylinder near the inlet port in a direction away from the inlet port along a longitudinal centerline of the cylinder and injecting a second portion of the main charge through a main injection site on the cylinder near the exhaust port in a direction away from the exhaust port and along the longitudinal centerline.

7. The method of claim 6, wherein the pistons cover the main injection sites while moving toward each other.

8. The method of claim 1, wherein injecting a main charge includes injecting at least a portion of the main charge through at least one main injection site on the cylinder near top dead center of the pistons.

9. The method of claim 1, further including swirling the air introduced into the cylinder.

10. The method of claim 1, further including electrically augmenting ignition of the main charge.

11. The method of claim 1, wherein the main charge includes diesel fuel.

12. The method of claim 11, wherein the pilot charge includes diesel fuel.

13. A method of operating an opposed piston compression ignition engine including a cylinder with opposing pistons disposed in the cylinder and spaced apart inlet and exhaust ports, comprising:

introducing air into the cylinder between the pistons;

moving the pistons toward each other;

injecting a lean main charge of liquid fuel into the cylinder between the pistons through at least one main injection site on the cylinder between the inlet port and the exhaust port;

in response to movement of the pistons, the main charge fully evaporating before an autoignition temperature is reached; and

then

injecting a pilot charge of liquid fuel through at least one pilot injection site near the longitudinal midpoint of the cylinder;

the pilot charge igniting the evaporated main charge.

14. The method of claim 13, wherein the mass of the pilot charge is less than the mass of the main charge required to idle the engine.

15. The method of claim 13, wherein injecting the main charge includes injecting a first portion of the main charge through a main injection site on the cylinder near the inlet port and injecting a second portion of the main charge through a main injection site on the cylinder near the exhaust port.

16. The method of claim 15, wherein the pistons cover the main injection sites while moving toward each other to compress the air/fuel mixture.

17. The method of claim 13, wherein injecting a main charge includes injecting a first portion of the main charge through a main injection site on the cylinder near the inlet port in a direction away from the inlet port along a longitudinal centerline of the cylinder and injecting a second portion of the main charge through a main injection site on the cylinder near the exhaust port in a direction away from the exhaust port and along the longitudinal centerline.

18. The method of claim 17, wherein the pistons cover the main injection sites while moving toward each other to compress the air/fuel mixture.

19. The method of claim 13, wherein injecting a main charge includes injecting at least a portion of the main charge through at least one main injection site on the cylinder near the longitudinal midpoint of the cylinder in directions toward the inlet and exhaust ports.

20. The method of claim 13, wherein the main charge and the pilot charge include diesel fuel.

21. A compression ignition engine, comprising:

a cylinder;

a pair of opposing pistons slidably disposed in the cylinder;

spaced-apart inlet and exhaust ports near respective ends of the cylinder;

at least one main fuel injector communicating with the bore of the cylinder through an injector site in the cylinder between the inlet port and the exhaust port;

at least one pilot fuel injector communicating with the bore through an injector site in the cylinder near a longitudinal midpoint of the cylinder; and

a fuel injection system coupled to the at least one main fuel injector and to the at least one pilot fuel injector for operating the at least one main fuel injector when the pistons are near bottom dead center positions and then operating the at least one pilot fuel injector when the pistons are near top dead center positions.

22. The engine of claim 21, wherein the at least one main fuel injector includes a first main fuel injector for injecting a first portion of the main charge through a main injection site on the cylinder near the inlet port and a second main fuel injector for injecting a second portion of the main charge through a main injection site on the cylinder near the exhaust port.

23. The engine of claim 21, wherein the at least one main fuel injector includes a first main fuel injector for injecting a first portion of the main charge through a main injection site on the cylinder near the inlet port in a direction toward the longitudinal midpoint and a second main fuel injector for injecting a second portion of the main charge through a main injection site on the cylinder near the exhaust port in a direction toward the longitudinal midpoint.

24. The engine of claim 21, wherein the at least one main fuel injector includes a main fuel injector for injecting at least a portion of the main charge through at least one main injection site on the cylinder near top dead center locations of the pistons in directions toward the inlet and outlet ports.

25. The engine of claim 21, wherein the fuel injection system controls the mass of the main charge in response to at least one engine operating condition and maintains the mass of the pilot charge at a magnitude less than the magnitude of the mass of the main charge required to idle the engine.

26. An internal combustion engine, comprising:

a cylinder with spaced-apart inlet and exhaust ports;

opposing pistons disposed in a central bore of the cylinder;

a first main fuel injector positioned at an injection site on the cylinder near the inlet port;

a second main fuel injector positioned at an injection site on the cylinder near the exhaust port;

a main fuel injection system connected to the main fuel injectors;

a pilot fuel injector positioned at an injection site between respective top dead center positions of the pistons; and

a pilot fuel injection system connected to the pilot fuel injector.

27. The engine of claim 26, wherein the first main fuel injector is for injecting a first portion of a main charge of liquid fuel in a direction away from the inlet port and the second main fuel injector is for injecting a second portion of the main charge of liquid fuel in a direction away from the exhaust port.

28. The engine of claim 27, wherein the main fuel injection system is for providing diesel fuel to the first and second main fuel injectors.

29. The engine of claim 28, wherein the pilot fuel injection system is for providing diesel fuel the pilot fuel injector.

30. An internal combustion engine, comprising:

a cylinder with spaced-apart inlet and exhaust ports;

opposing pistons disposed in the bore of the cylinder;

at least one main fuel injector communicating with the bore through at least one injection site on the cylinder between the inlet port and the exhaust port;

a main fuel injection system connected to the at least one main fuel injector for operating the at least one main fuel injector when the pistons are near bottom dead center positions;

a pilot fuel injector communicating with the bore through at least one injection site near a longitudinal midpoint of the cylinder;

a pilot fuel injection system connected to the pilot fuel injector for operating the pilot fuel injector when the pistons are near top dead center positions; and

an electrical ignition element mounted to the cylinder.

31. The internal combustion engine of claim 30, further including a scroll in the inlet port.

32. A fuel injection combination for an opposed piston compression ignition engine, comprising:

a cylinder with spaced-apart inlet and exhaust ports;

opposing pistons disposed in a bore of the cylinder for moving between bottom dead center and top dead center positions;

at least one main fuel injector communicating with the bore through at least one injection site on the cylinder between the inlet port and the exhaust port;

at least one pilot fuel injector communicating with the bore through at least one injection site near a longitudinal midpoint of the cylinder; and

control means for operating the least one main fuel injector when the pistons are near their bottom dead center positions and operating the at least one pilot fuel injector when the pistons are near their top dead center positions.

33-35. -35. (canceled)

36. A fuel injection combination for an opposed piston compression ignition engine, comprising:

a cylinder with spaced-apart inlet and exhaust ports;

opposing pistons disposed in a bore of the cylinder;

a first main fuel injector communicating with the bore through a first main injection site on the cylinder near the inlet port, the first main fuel injector for injecting a first portion of a main charge of liquid fuel through the first main injection site in a direction toward the longitudinal midpoint; and

a second main fuel injector communicating with the bore through a second main injection site on the cylinder near the exhaust port, the second main fuel injector for injecting a second portion of the main charge of liquid fuel through the second main injection site in a direction toward the longitudinal midpoint.

37. (canceled)

38. An opposed piston compression ignition engine, comprising:

at least one cylinder with spaced-apart inlet and exhaust ports, a bore and a longitudinal midpoint;

opposed pistons disposed in the bore for moving between top dead center and bottom dead center positions;

at least one main fuel injector communicating with the bore through at least one main injection site on the cylinder between the inlet and exhaust ports;

at least one pilot fuel injector communicating with the bore through a pilot injection site on the cylinder near the longitudinal midpoint; and

control means for operating the at least one main fuel injector when the pistons are near their bottom dead center positions and operating the at least one pilot fuel injector when the pistons are near their top dead center positions.

39. The opposed piston compression ignition engine of claim 38, wherein the at least one main injection site includes a main injection site near the exhaust port.

40. The opposed piston compression ignition engine of claim 38, wherein the at least one main injection site includes a main injection site near the inlet port.

41. The opposed piston compression ignition engine of claim 38, the at least one main fuel injector including a first main fuel injector communicating with the bore through a main injection site on the cylinder near the exhaust port and a second main fuel injector communicating with the bore through a main injection site on the cylinder near the inlet port.