Engine valve actuation system

• US 20030213443A1
• Filed: 10/30/2002
• Published: 11/20/2003
• Est. Priority Date: 05/14/2002
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Cornell, Sean O., Leman, Scott Alan
• Granted Patent: US 7,004,122 B2
• Time in Patent Office: Days
• US Class Current: 123/90.12
• CPC Class Codes: F01L 1/146 Push-rods
• CPC Class Codes: F01L 1/26 characterised by the provision of two or more valves operated simultaneously by same transmitting-gear; peculiar to machines or engines with more than two lift-valves per cylinder with coaxial valves F01L1/28
• CPC Class Codes: F01L 13/0015 for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
• CPC Class Codes: F01L 13/06 for braking
• CPC Class Codes: F01L 13/065 Compression release engine retarders of the "Jacobs Manufacturing" type
• CPC Class Codes: F01L 2001/34446 Fluid accumulators for the feeding circuit
• CPC Class Codes: F01L 2013/0089 with means for delaying valve closing
• CPC Class Codes: F01L 2305/00 Valve arrangements comprising rollers
• CPC Class Codes: F01L 2800/00 Methods of operation using a variable valve timing mechanism
• CPC Class Codes: F01L 9/10 by fluid means, e.g. hydraulic
• 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: F02D 13/0269 Controlling the valves to perform a Miller-Atkinson cycle
• CPC Class Codes: F02D 15/04 by alteration of volume of compression space without changing piston stroke
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

An engine valve actuation system is provided. The engine valve actuation system includes an intake valve that is moveable between a first position to prevent a flow of fluid and a second position to allow a flow of fluid. A cam assembly is configured to move the intake valve between the first position and the second position. A fluid actuator is configured to selectively prevent the intake valve from moving to the first position. A source of fluid is in fluid communication with the fluid actuator. A directional control valve is configured to control a flow of fluid between the source of fluid and the fluid actuator. A fluid passageway connects the directional control valve with the fluid actuator. An accumulator is in fluid communication with the fluid passageway. A restricted orifice is disposed between the accumulator and the fluid passageway to restrict a flow of fluid between the accumulator and the fluid passageway.

Claims

1. An engine valve actuation system, comprising:

an intake valve moveable between a first position to prevent a flow of fluid and a second position to allow a flow of fluid;

a cam assembly configured 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;

a fluid passageway connecting the directional control valve with the fluid actuator;

an accumulator in fluid communication with the fluid passageway; and

a restricted orifice disposed between the accumulator and the fluid passageway to restrict a flow of fluid between the accumulator and the fluid passageway.

2. The engine valve actuation system of claim 1, further including a control valve disposed between the source of fluid and the directional control valve and moveable between a first position to prevent a flow of fluid between the source of fluid and the directional control valve and a second position to allow the flow of fluid from the source of fluid to the directional control valve.

3. The engine valve actuation system of claim 2, further including a controller configured to move the control valve between the first position and the second position.

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

5. The engine valve actuation system of claim 1, further including a check valve, wherein the check valve and the directional control valve are disposed in parallel between the fluid actuator and the control valve.

6. The engine valve actuation system of claim 5, wherein the check valve includes a seat, a poppet, and a spring acting on the poppet to engage the poppet with the seat.

7. The engine valve actuation system of claim 1, wherein the directional control valve includes a spring acting to bias the directional control valve into a first position where directional control valve allows the flow of fluid between the source of fluid and the fluid actuator.

8. The engine valve actuation system of claim 1, further including a hydraulic snubbing valve configured to control the rate of fluid flow from the fluid actuator.

9. The engine valve actuation system of claim 1, wherein the accumulator includes a chamber, a piston moveable between a first position where the volume of the chamber is minimized and a second position where the volume of the chamber is maximized, and a spring acting on the piston to bias the piston towards the first position.

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

rotating a cam to move an intake valve between a first position to prevent a flow of fluid and a second position to allow a flow of fluid during the intake stroke of the piston;

directing fluid through a directional control valve and a fluid passageway to a fluid actuator associated with the intake valve when the intake valve is moved from the first position;

actuating the directional control valve to selectively prevent fluid from flowing through the fluid passageway from the fluid actuator to thereby prevent the intake valve from moving to the first position during at least a portion of the compression stroke of the piston; and

directing fluid from the fluid passageway through a restricted orifice to an accumulator to inhibit oscillations in the fluid actuator.

11. The method of claim 10, further including:

directing fluid through a control valve to the directional control valve;

sensing at least one operating parameter of the engine; and

moving the control valve to a closed position to prevent fluid from flowing to the directional control valve and the fluid actuator based on the sensed operating parameter of the engine.

12. The method of claim 11, wherein the at least one operating parameter is at least one of a coolant temperature, an oil temperature, an engine temperature, an ambient air temperature, an engine speed, an engine load, and an intake air pressure.

13. The method of claim 10, further including closing the directional control valve to prevent fluid from releasing from the fluid actuator to thereby prevent the intake valve from moving to the first position.

14. A fluid actuator for selectively preventing an engine valve from closing, comprising:

a housing having an inlet, a snubbing valve chamber, an actuator chamber, a first fluid passageway connecting the inlet with the snubbing valve chamber, a second fluid passageway connecting the inlet with the snubbing valve chamber, and a third fluid passageway connecting the snubbing valve chamber with the actuator chamber;

a snubbing valve disposed in the snubbing valve chamber and adapted to control a flow rate of fluid through the fluid passageway;

a check valve disposed in the first fluid passageway and adapted to allow a flow of fluid from the inlet through the first fluid passageway to the snubbing valve chamber and to prevent a flow of fluid from the snubbing valve chamber through the first fluid passageway to the inlet;

an accumulator in fluid communication with the first and second fluid passageways;

a restricted orifice disposed between the first and second fluid passageways and the accumulator; and

a piston having an actuator rod and being disposed in the actuator chamber, the piston adapted to move the actuator rod into an engine valve actuation position in response to an introduction of fluid to the actuator chamber.

15. The actuator of claim 14, wherein the inlet includes a first opening for the first fluid passageway and a second opening for the second fluid passageway.

16. The actuator of claim 14, further including a spring acting on the piston to move the actuator rod away from the engine valve actuation position.

17. The actuator of claim 14, wherein the accumulator includes a chamber, a piston moveable between a first position where the volume of the chamber is minimized and a second position where the volume of the chamber is maximized, and a spring acting on the piston to bias the piston towards the first position.

18. The actuator of claim 14, wherein the check valve includes a seat, a poppet, and a spring acting on the poppet to engage the poppet with the seat.

19. The actuator of claim 14, further including a piston stop adapted to stop the piston when the actuator rod reaches the engine valve actuation position.

20. 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;

a fluid passageway connecting the directional control valve with the fluid actuator;

an accumulator in fluid communication with the fluid passageway; and

a restricted orifice disposed between the accumulator and the fluid passageway to restrict a flow of fluid between the accumulator and the fluid passageway.

21. The engine of claim 20, further including a control valve disposed between the source of fluid and the directional control valve and moveable between a first position to prevent a flow of fluid between the source of fluid and the directional control valve and a second position to allow the flow of fluid from the source of fluid to the directional control valve.

22. The engine of claim 21, further including a controller configured to move the control valve between the first position and the second position.

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

24. The engine of claim 20, further including a check valve, wherein the check valve and the directional control valve are disposed in parallel between the fluid actuator and the control valve.

25. The engine of claim 24, wherein the check valve includes a seat, a poppet, and a spring acting on the poppet to engage the poppet with the seat.

26. The engine of claim 20, wherein the directional control valve includes a spring acting to bias the directional control valve into a first position where directional control valve allows the flow of fluid between the source of fluid and the fluid actuator.

27. The engine of claim 20, further including a hydraulic snubbing valve configured to control the rate of fluid flow from the fluid actuator.

28. The engine of claim 20, wherein the accumulator includes a chamber, a piston moveable between a first position where the volume of the chamber is minimized and a second position where the volume of the chamber is maximized, and a spring acting on the piston to bias the piston towards the first position.