Engine valve actuation system

• US 20050034691A1
• Filed: 08/15/2003
• Published: 02/17/2005
• Est. Priority Date: 08/15/2003
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Chang, David Yu-Zhang
• Granted Patent: US 7,318,398 B2
• Time in Patent Office: Days
• US Class Current: 123/90.120
• CPC Class Codes: F01L 9/10 by fluid means, e.g. hydraulic

Abstract

An engine valve actuation system includes an engine valve moveable between a first position that blocks a flow of fluid and a second position that allows a flow of fluid. The system also includes a valve actuation assembly connected to move the engine valve between the first position and the second position and a fluid actuator configured to selectively modify a timing of the engine valve in moving from the second position to the first position. The fluid actuator includes a first piston. The system further includes an accumulator including a second piston, wherein the second piston is slidably movable in the first piston.

Claims

1. An engine valve actuation system, comprising:

an engine valve moveable between a first position that blocks a flow of fluid and a second position that allows a flow of fluid;

a valve actuation assembly connected to move the engine valve between the first position and the second position;

a fluid actuator configured to selectively modify a timing of the engine valve in moving from the second position to the first position, the fluid actuator including a first piston; and

an accumulator including a second piston, the second piston being slidably movable in the first piston.

2. The engine valve actuation system of claim 1, further including a snubbing valve configured to restrict a flow of fluid from the fluid actuator.

3. The engine valve actuation system of claim 2, wherein the fluid actuator includes the first piston slidably movable in an actuator cylinder.

4. The engine valve actuation system of claim 3, wherein the snubbing valve includes a snubber slidably movable in the actuator cylinder.

5. The engine valve actuation system of claim 3, further including a stop member cooperating with the actuator cylinder to retain at least a portion of the first piston in the actuator cylinder.

6. The engine valve actuation system of claim 5, further including a flow path configured to prevent hydraulic lock of the first piston.

7. The engine valve actuation system of claim 6, wherein the flow path includes at least one flow passage in the first piston and at least one flow passage in the stop member in fluid communication with a tank.

8. The engine valve actuation system of claim 1, further including a restrictive orifice associated with the accumulator.

9. The engine valve actuation system of claim 1, further including a source of fluid in selective fluid communication with the fluid actuator.

10. The engine valve actuation system of claim 9, further including:

a fluid rail having a first end and a second end, the fluid rail being configured to supply fluid to the fluid actuator; and

a fluid tank in selective fluid communication with the fluid rail.

11. The engine valve actuation system of claim 10, further including a control valve configured to control a flow of fluid from the fluid rail to the fluid tank, the control valve being moveable between a first position that blocks a flow of fluid from the fluid rail to the fluid tank and a second position that allows a flow of fluid from the fluid rail to the fluid tank.

12. The engine valve actuation system of claim 10, further including a restrictive orifice disposed between the source of fluid and the fluid rail.

13. The engine valve actuation system of claim 9, further including a directional control valve configured to control a flow of fluid between the source of fluid and the fluid actuator.

14. The engine valve actuation system of claim 13, further including a check valve, wherein the check valve and the directional control valve are disposed in parallel between the fluid actuator and the source of fluid.

15. The engine valve actuation system of claim 14, further including an air bleed valve disposed between the check valve and the fluid actuator.

16. The engine valve actuation system of claim 9, wherein the source of fluid provides fluid having a pressure of between about 210 KPa and 620 KPa to the fluid rail.

17. A method of assembling an engine valve actuation system, comprising:

operably coupling a valve actuation assembly with an engine valve such that the valve actuation assembly is configured to move the engine valve between a first position that blocks a flow of fluid and a second position that allows a flow of fluid;

inserting an accumulator including an accumulator piston at least partially in an actuator piston such that the accumulator piston is slidably movable in the actuator piston;

inserting a fluid actuator including the actuator piston at least partially in an actuator cylinder such that the actuator piston is slidably movable in the actuator cylinder; and

operably coupling the fluid actuator with the engine valve such that the fluid actuator is configured to selectively modify a timing of the engine valve in moving from the second position to the first position, the fluid actuator including a first piston.

18. The method of claim 17, further including inserting a snubbing valve including a snubber in the actuator cylinder such that the snubber is slidably movable in the actuator cylinder.

19. The method of claim 17, further including coupling a stop member with the actuator cylinder to retain at least a portion of actuator piston in the actuator cylinder, the stop member defining at least a portion of a flow path configured to prevent hydraulic lock of the actuator piston.

20. An engine, comprising:

an engine having a block defining at least one cylinder and a cylinder head having at least one passageway leading to the at least one cylinder;

at least one engine valve moveable between a first position to prevent a flow of fluid through the at least one passageway and a second position to allow a flow of fluid through the at least one passageway;

a valve actuation assembly connected to the engine valve to move the engine valve between the first position and the second position;

a fluid actuator configured to selectively prevent the engine valve from moving to the first position, the fluid actuator including a first piston operatively associated with the engine valve;

an accumulator including a second piston, the second piston being slidably movable in the first piston;

a source of fluid in fluid communication with the fluid actuator;

a directional control valve configured to control a flow of fluid between the source of fluid and the fluid actuator; and

a snubbing valve configured to restrict a flow of fluid from the fluid actuator.

21. An engine valve actuation system, comprising:

an engine valve moveable between a first position that blocks a flow of fluid and a second position that allows a flow of fluid;

a fluid actuator having a housing, a longitudinal axis, and an actuator piston slidably disposed in the housing and movable substantially along the longitudinal axis to selectively modify a timing of the engine valve in moving from the second position to the first position;

a snubber slidably disposed in the housing and movable substantially along the longitudinal axis; and

an accumulator piston slidably disposed in the housing and movable substantially along the longitudinal axis.

22. The engine valve actuation system of claim 21, further including an adjustment member configured to variably adjust a distance between a free end of the first piston and the engine valve.

23. The engine valve actuation system of claim 21, further including a flow path configured to prevent hydraulic lock of the first piston.

24. The engine valve actuation system of claim 21, wherein the accumulator piston delimits a variable volume chamber in a bore of the actuator piston.

25. An engine valve actuation system, comprising:

an engine valve moveable between a first position that blocks a flow of fluid and a second position that allows a flow of fluid;

a valve actuation assembly connected to move the engine valve between the first position and the second position;

a fluid actuator configured to selectively modify a timing of the engine valve in moving from the second position to the first position, the fluid actuator including a first piston; and

an accumulator configured to dissipate energy from the engine valve actuation system, wherein the accumulator changes location during actuation of the fluid actuator.

26. The engine valve actuation system of claim 25, further including a snubbing valve configured to restrict a flow of fluid from the fluid actuator.

27. The engine valve actuation system of claim 26, wherein the fluid actuator includes the first piston slidably movable in an actuator cylinder.

28. The engine valve actuation system of claim 27, wherein the snubbing valve includes a snubber slidably movable in the actuator cylinder.

29. The engine valve actuation system of claim 27, further including a stop member cooperating with the actuator cylinder to retain at least a portion of the first piston in the actuator cylinder.

30. The engine valve actuation system of claim 29, further including a flow path configured to prevent hydraulic lock of the first piston.

31. The engine valve actuation system of claim 30, wherein the flow path includes at least one flow passage in the first piston and at least one flow passage in the stop member in fluid communication with a tank.

32. The engine valve actuation system of claim 25, further including a restrictive orifice associated with the accumulator.

33. The engine valve actuation system of claim 25, further including a source of fluid in selective fluid communication with the fluid actuator.

34. The engine valve actuation system of claim 33, further including:

a fluid rail having a first end and a second end, the fluid rail being configured to supply fluid to the fluid actuator; and

a fluid tank in selective fluid communication with the fluid rail.

35. The engine valve actuation system of claim 34, further including a control valve configured to control a flow of fluid from the fluid rail to the fluid tank, the control valve being moveable between a first position that blocks a flow of fluid from the fluid rail to the fluid tank and a second position that allows a flow of fluid from the fluid rail to the fluid tank.

36. The engine valve actuation system of claim 34, further including a restrictive orifice disposed between the source of fluid and the fluid rail.

37. The engine valve actuation system of claim 33, further including a directional control valve configured to control a flow of fluid between the source of fluid and the fluid actuator.

38. The engine valve actuation system of claim 37, further including a check valve, wherein the check valve and the directional control valve are disposed in parallel between the fluid actuator and the source of fluid.

39. The engine valve actuation system of claim 38, further including an air bleed valve disposed between the check valve and the fluid actuator.

40. The engine valve actuation system of claim 33, wherein the source of fluid provides fluid having a pressure of between about 210 KPa and 620 KPa to the fluid rail.

41. An engine valve actuation system, comprising:

an engine valve moveable between a first position that blocks a flow of fluid and a second position that allows a flow of fluid;

a valve actuation assembly connected to move the engine valve between the first position and the second position;

a fluid actuator configured to selectively modify a timing of the engine valve in moving from the second position to the first position, the fluid actuator including a first piston; and

an accumulator having an accumulator piston, a spring, and a variable volume chamber, the accumulator piston, spring, and variable volume chamber being disposed within the first piston.

42. The engine valve actuation system of claim 41, further including a snubbing valve configured to restrict a flow of fluid from the fluid actuator.

43. The engine valve actuation system of claim 42, wherein the fluid actuator includes the first piston slidably movable in an actuator cylinder.

44. The engine valve actuation system of claim 43, wherein the snubbing valve includes a snubber slidably movable in the actuator cylinder.

45. The engine valve actuation system of claim 43, further including a stop member cooperating with the actuator cylinder to retain at least a portion of the first piston in the actuator cylinder.

46. The engine valve actuation system of claim 45, further including a flow path configured to prevent hydraulic lock of the first piston.

47. The engine valve actuation system of claim 46, wherein the flow path includes at least one flow passage in the first piston and at least one flow passage in the stop member in fluid communication with a tank.

48. The engine valve actuation system of claim 41, further including a restrictive orifice associated with the accumulator.

49. The engine valve actuation system of claim 41, further including a source of fluid in selective fluid communication with the fluid actuator.

50. The engine valve actuation system of claim 49, further including:

a fluid rail having a first end and a second end, the fluid rail being configured to supply fluid to the fluid actuator; and

a fluid tank in selective fluid communication with the fluid rail.

51. The engine valve actuation system of claim 50, further including a control valve configured to control a flow of fluid from the fluid rail to the fluid tank, the control valve being moveable between a first position that blocks a flow of fluid from the fluid rail to the fluid tank and a second position that allows a flow of fluid from the fluid rail to the fluid tank.

52. The engine valve actuation system of claim 50, further including a restrictive orifice disposed between the source of fluid and the fluid rail.

53. The engine valve actuation system of claim 49, further including a directional control valve configured to control a flow of fluid between the source of fluid and the fluid actuator.

54. The engine valve actuation system of claim 53, further including a check valve, wherein the check valve and the directional control valve are disposed in parallel between the fluid actuator and the source of fluid.

55. The engine valve actuation system of claim 54, further including an air bleed valve disposed between the check valve and the fluid actuator.

56. The engine valve actuation system of claim 49, wherein the source of fluid provides fluid having a pressure of between about 210 KPa and 620 KPa to the fluid rail.