Hydraulic valve actuation systems and methods

Abstract

Hydraulic engine valve actuation systems and methods for internal combustion engines. The systems utilize a proportional valve to regulate the flow of a working fluid to and from a hydraulic actuator controlling the engine valve position. The position of the proportional valve is controlled by high speed valves to control various engine valve parameters, including engine valve takeoff and landing velocities. Returning all valves to a known starting position between engine valve events avoids accumulation of errors in proportional valve positioning. Embodiments using spool valves for the high speed valves and the proportional valve, and spring return and hydraulic return for the engine valve, are disclosed. A specially shaped spool in the proportional valve provides enhanced control over the engine valve operation. Various further alternate embodiments are disclosed.

What is claimed is:  
     
         1 . Apparatus for opening an engine valve comprising: 
 a hydraulic actuator disposed with respect to the valve to encourage the valve toward a valve open position by the pressure of a fluid in the hydraulic actuator;    a proportional spool valve having a spool hydraulically moveable between a first position coupling a source of fluid under a first pressure to the hydraulic actuator and a second position coupling the hydraulic actuator to a reservoir of fluid under a second pressure, the second pressure being less than the first pressure;    electrically controlled valving hydraulically controlling the position of the spool between the first and second positions; and,    a valve return returning the valve to a closed position.    
     
     
         2 . The apparatus of  claim 1  wherein the spool valve has a third position between the first and second positions blocking the source of fluid under a first pressure from the hydraulic actuator blocking the hydraulic actuator from the reservoir of fluid under the second pressure.  
     
     
         3 . The apparatus of  claim 1  wherein the second pressure is atmospheric pressure.  
     
     
         4 . The apparatus of  claim 1  wherein the spool is stepped in diameter to shape the area versus spool position for flow between the source of fluid under the first pressure and the hydraulic actuator, and the hydraulic actuator to the reservoir of fluid under the second pressure.  
     
     
         5 . The apparatus of  claim 1  wherein the valving comprises double solenoid latching spool valves.  
     
     
         6 . A method of opening an engine valve comprising: 
 providing a hydraulic actuator disposed with respect to the valve to encourage the valve toward a valve open position by the pressure of a fluid in the hydraulic actuator;    coupling the hydraulic actuator to a proportional spool valve having a spool hydraulically moveable between a first position coupling a source of fluid under a first pressure to the hydraulic actuator and a second position coupling the hydraulic actuator to a reservoir of fluid under a second pressure, the second pressure being less than the first pressure; and,    hydraulically controlling the position of the spool between the first and second positions by electrically controlled valving.