Engine valve actuation system

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.

What is claimed is:  
     
         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.