Method for valve seating control for an electro-hydraulic engine valve
Valve lift in an internal combustion engine is controlled by an electro-hydraulic actuation mechanism including a selectively actuable hydraulic feedback circuit.
1. A method for operating an electro-hydraulic actuation mechanism operative to urge a moveable engine valve to a lift, comprising:
commanding the engine valve to a desired lift;
activating a first spool valve to permit flow of pressurized hydraulic fluid through a second spool valve to a main hydraulic chamber, the main hydraulic chamber configured to urge the engine valve to the desired lift;
monitoring lift of the engine valve; and
commanding an on/off valve to a closed position when the monitored lift of the engine valve approaches the desired lift to effect flow of pressurized hydraulic fluid from one of a second and a third hydraulic chamber to a fluid chamber of the second spool valve, the second spool valve configured to terminate the flow of pressurized hydraulic flow from the first spool valve to the main hydraulic chamber to stop opening of the engine valve at the desired lift.
2. The method of claim 1 , wherein commanding the on/off valve to the closed position when the monitored lift of the engine valve approaches the desired lift to effect flow of pressurized hydraulic fluid from one of the second and the third hydraulic chamber to the fluid chamber of the second spool valve comprises commanding the on/off valve to the closed position when the monitored lift is a predetermined distance from the desired lift.
3. The method of claim 1 , wherein commanding the engine valve to the desired lift comprises commanding the engine valve to an open position.
4. The method of claim 1 , wherein commanding the engine valve to the desired lift comprises commanding the engine valve to a closed position.
5. The method of claim 1 , wherein activating the first spool valve to permit flow of pressurized hydraulic fluid through the second spool valve to the main hydraulic chamber to urge the engine valve to the desired lift further comprises exhausting pressurized hydraulic fluid from the second hydraulic chamber.
6. The method of claim 1 , wherein the second spool valve is configured to terminate the flow of pressurized hydraulic flow from the first spool valve to the main hydraulic chamber to stop opening of the engine valve at the desired lift when there is sufficient flow of pressurized hydraulic fluid from one of the second and the third hydraulic chambers to the fluid chamber of the second spool valve.
7. A method for controlling a moveable engine valve to a desired lift, comprising:
equipping the moveable engine valve with an electro-hydraulic valve actuator assembly including a main hydraulic chamber, a second hydraulic chamber, first and second spool valves, and first and second on/off flow control valves, the electro-hydraulic valve actuator assembly operable to urge the engine valve to a lift;
commanding the engine valve to a desired lift, the desired lift corresponding to an open position;
controlling the first spool valve to permit flow of pressurized hydraulic fluid through the second spool valve to the main hydraulic chamber to urge the moveable engine valve to the desired lift;
monitoring lift of the engine valve; and
commanding one of the first and second on/off flow control valves to a closed position when the monitored lift of the engine valve approaches the desired lift to effect flow of pressurized hydraulic fluid from the second hydraulic chamber to a fluid chamber of the second spool valve, the second spool valve configured to terminate the flow of pressurized hydraulic flow from the first spool valve to the main hydraulic chamber to stop opening of the engine valve at the desired lift.
8. The method of claim 7 , wherein commanding one of the first and second on/off flow control valves to a closed position when the monitored lift of the engine valve approaches the desired lift to effect flow of pressurized hydraulic fluid from the second hydraulic chamber to a fluid chamber of the second spool valve comprises commanding the one of the first and second on/off flow control valves to the closed position when the monitored lift of the engine valve achieves a position-certain a predetermined distance from the desired lift.
9. The method of claim 7 , wherein the second spool valve is configured to terminate the flow of pressurized hydraulic flow from the first spool valve to the main hydraulic chamber to stop opening of the engine valve at the desired lift corresponding to the closed position when there is a sufficient flow of pressurized hydraulic fluid from the second hydraulic chamber to the fluid chamber of the second spool valve.
10. A method for controlling closing of an open moveable engine valve, comprising:
equipping the moveable engine valve with an electro-hydraulic valve actuator assembly including a main hydraulic chamber, a second hydraulic chamber, a third hydraulic chamber, first and second spool valves, and first and second on/off flow control valves, the electro-hydraulic valve actuator assembly operable to urge the engine valve to an open position;
commanding the engine valve to a desired lift, the desired lift corresponding to the closed position;
controlling the first spool valve to permit flow of pressurized hydraulic fluid from the main hydraulic chamber through the second spool valve to a drain;
commanding the first on/off flow control valve to an open position to initiate closing of the engine valve;
monitoring lift of the engine valve; and
commanding the second on/off flow control valve to a closed position when the monitored lift of the engine valve approaches the desired lift corresponding to the closed position to effect flow of pressurized hydraulic fluid from the third hydraulic chamber to a fluid chamber of the second spool valve, the second spool valve configured to terminate the flow of pressurized hydraulic flow from the first spool valve to the main hydraulic chamber to stop closing of the engine valve at the desired lift corresponding to the closed position.
11. The method of claim 10 , wherein commanding the second on/off flow control valve to the closed position when the monitored lift of the engine valve approaches the desired lift corresponding to the closed position to effect flow of pressurized hydraulic fluid from the third hydraulic chamber to the fluid chamber of the second spool valve comprises commanding the second on/off flow control valve to the closed position when the monitored lift of the engine valve is a predetermined distance from the closed position.
12. The method of claim 10 , wherein the second spool valve is configured to terminate the flow of pressurized hydraulic flow from the first spool valve to the main hydraulic chamber to stop opening of the engine valve at the desired lift corresponding to the closed position when there is a sufficient flow of pressurized hydraulic fluid from the third hydraulic chamber to the fluid chamber of the second spool valve.