Engine valve actuation system

• US 20030213444A1
• Filed: 12/04/2002
• Published: 11/20/2003
• Est. Priority Date: 05/14/2002
• Status: Abandoned Application

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Cornell, Sean O., Leman, Scott Alan
• Application Number:
  US10/309,312
• Publication Number:
  US 20030213444A1
• Time in Patent Office: Days
• US Class Current: 123/90.12
• CPC Class Codes: F01L 13/06 for braking
• CPC Class Codes: F01L 2001/34446 Fluid accumulators for the feeding circuit
• CPC Class Codes: F01L 9/12 with a liquid chamber between a piston actuated by a cam and a piston acting on a valve stem
• CPC Class Codes: F02B 2275/32 Miller cycle
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

An engine valve actuation system that includes an intake 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 cam assembly connected to move the intake valve between the first position and the second position and a fluid actuator configured to selectively modify a timing of the intake valve in moving from the second position to the first position. A snubbing valve is configured to restrict a flow of fluid from the fluid actuator so as to reduce a rate of movement of the intake valve to the first position.

Claims

1. An engine valve actuation system, comprising:

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

a cam assembly connected to move the intake valve between the first position and the second position;

a fluid actuator configured to selectively modify a timing of the intake valve in moving from the second position to the first position; and

a snubbing valve configured to restrict a flow of fluid from the fluid actuator so as to reduce a rate of movement of the intake valve to the first position.

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

3. The engine valve actuation system of claim 2, 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.

4. The engine valve actuation system of claim 3, 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.

5. The engine valve actuation system of claim 4, further including a controller configured to move the control valve between the first position and the second position.

6. The engine valve actuation system of claim 3, further including a restrictive orifice disposed between the source of fluid and the fluid rail.

7. The engine valve actuation system of claim 2, further including a directional control valve configured to control a flow of fluid between the source of fluid and the fluid actuator.

8. The engine valve actuation system of claim 7, 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.

9. The engine valve actuation system of claim 8, further including an air bleed valve disposed between the check valve and the fluid actuator.

10. The engine valve actuation system of claim 7, wherein the directional control valve includes a spring urging the directional control valve into a first position that blocks a flow of fluid from the source of fluid to the fluid actuator.

11. The engine valve actuation system of claim 7, wherein the directional control valve includes a spring urging the directional control valve into a second position that allows a flow of fluid from the source of fluid to the fluid actuator.

12. The engine valve actuation system of claim 2, wherein the source of fluid provides fluid having a pressure of between about 210 KPa and 620 KPa to the fluid rail.

13. The engine valve actuation system of claim 1, further including an accumulator and a restricted orifice, the restricted orifice being disposed between the fluid actuator and the accumulator.

14. The engine valve actuation system of claim 1, wherein the fluid actuator includes a piston operatively associated with the intake valve.

15. A method of controlling an engine having a piston moveable through an intake stroke followed by a compression stroke, comprising:

cammingly moving an intake valve between a first position that blocks a flow of fluid and a second position that allows a flow of fluid during the intake stroke of the piston;

directing fluid to a fluid actuator associated with the intake valve when the intake valve is away from the first position; and

restricting a flow of fluid from the fluid actuator during at least a portion of the compression stroke to reduce a velocity of the intake valve movement to the first position.

16. The method of claim 15, further including blocking fluid from flowing from the fluid actuator to modify a timing of movement of the intake valve to the first position during at least a portion of the compression stroke of the piston.

17. The method of claim 16, wherein said restricting occurs after said blocking.

18. The method of claim 15, further including allowing fluid to flow from the fluid actuator to allow the intake valve to move to the first position.

19. An engine, comprising:

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

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

a cam assembly connected to the intake valve to move the intake valve between the first position and the second position;

a fluid actuator configured to selectively prevent the intake valve from moving to the first position;

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 so as to reduce a rate of movement of the intake valve to the first position.

20. The engine of claim 19, wherein the fluid actuator includes a piston operatively associated with the intake valve.