Systems and methods for lash adjustment and cylinder deactivation for internal combustion engines

Abstract

Valve actuation mechanisms are provided for hydraulically controlling cylinder deactivation and variable valve lift operations. The valve actuation mechanisms include a hydraulic circuit that is selectively pressurized to secure a reciprocating member in an extended position to transfer motion from the camshaft lobe to the intake valves or exhaust valves, and vented to allow the reciprocating member to reciprocate.

What is claimed is: 
     
         1 . A system for valve actuation for an internal combustion engine, the system comprising:
 at least one rocker assembly linking at least one valve for opening and closing an associated cylinder of the internal combustion engine to one or more camshaft lobes;   a reciprocating member connected with the rocker assembly, the reciprocating member including an extended configuration transferring motion from the one or more camshaft lobes to the at least one valve, and the reciprocating member including a movable configuration in which the reciprocating member reciprocates relative to the rocker assembly; and   a hydraulic circuit associated with the rocker assembly, the hydraulic circuit being closed in the extended configuration of the reciprocating member, and the hydraulic circuit is opened to allow reciprocation of the reciprocating member in the movable configuration.   
     
     
         2 . The system of  claim 1 , wherein the reciprocating member connects the at least one valve to a rocker lever. 
     
     
         3 . The system of  claim 1 , wherein the reciprocating member is connected to one end of a rocker lever and the at least one valve is connected to an opposite end of the rocker lever. 
     
     
         4 . The system of  claim 1 , wherein the hydraulic circuit is located at least partially within the rocker assembly. 
     
     
         5 . The system of  claim 1 , wherein the hydraulic circuit includes a first valve for admitting hydraulic fluid into the hydraulic circuit to pressurize the hydraulic circuit, and in the extended configuration of the reciprocating member the first valve is forced closed by the hydraulic fluid in response to a force acting on the reciprocating member. 
     
     
         6 . The system of  claim 5 , wherein the hydraulic circuit includes a hydraulically actuated second valve for opening the hydraulic circuit to vent the hydraulic fluid while the first valve is closed. 
     
     
         7 . The system of  claim 6 , wherein the hydraulic circuit includes an outlet downstream of the second valve for receiving the hydraulic fluid vented from the hydraulic circuit. 
     
     
         8 . The system of  claim 7 , wherein the outlet is connected to an accumulator, and the accumulator includes a plunger that is normally biased toward the outlet for leak down of the hydraulic fluid in the accumulator. 
     
     
         9 . The system of  claim 6 , wherein the second valve is normally biased to a closed position, and the second valve is hydraulically actuated from the closed position to an open position to vent the hydraulic circuit. 
     
     
         10 . The system of  claim 1 , wherein the hydraulic circuit includes a hydraulically actuated valve that is positionable to open the hydraulic circuit and vent hydraulic fluid through an outlet in response to a force acting on the reciprocating member in the movable configuration. 
     
     
         11 . The system of  claim 10 , wherein the hydraulically actuated valve includes a blocking portion for normally closing the outlet of the hydraulic circuit, and the blocking portion is movable out of the hydraulic circuit to open the outlet to vent hydraulic fluid. 
     
     
         12 . The system of  claim 1 , wherein the reciprocating member is normally biased toward an extended position and moves reciprocally relative to the rocker assembly in response to resistance from the at least one valve while the reciprocating member is in the movable configuration. 
     
     
         13 . A method for operating a valve actuation mechanism of an internal combustion engine, the method comprising:
 hydraulically securing a reciprocating member connected with a rocker assembly in an extended position to transfer motion from one or more camshaft lobes to at least one valve via the rocker assembly, the at least one valve being movable to open an close an associated cylinder of the internal combustion engine; and   allowing the reciprocating member to reciprocate from the extended position so that motion from the one or more camshaft lobes is lost to the at least one valve, wherein allowing the reciprocating member to reciprocate includes relieving the hydraulic fluid that hydraulically secures the reciprocating member in response to reciprocation of the reciprocating member.   
     
     
         14 . The method of  claim 13 , wherein hydraulically securing, the reciprocating member includes pressurizing a hydraulic circuit in fluid communication with the reciprocating member through a first valve. 
     
     
         15 . The method of  claim 14 , wherein hydraulically securing the reciprocating member includes closing the first valve in response to a force acting to displace the reciprocating member. 
     
     
         16 . The method of  claim 13 , wherein relieving the hydraulic fluid includes pressurizing a control fluid to displace a control valve that blocks the outlet for the hydraulic fluid. 
     
     
         17 . The method of  claim 13 , further comprising closing a first valve in a hydraulic fluid feed before hydraulically securing the reciprocating member. 
     
     
         18 . The method of  claim 17 , further comprising biasing the first valve to a closed position. 
     
     
         19 . The method of  claim 13 , wherein allowing the reciprocating member to reciprocate includes venting the hydraulic fluid into an accumulator, the accumulator including a plunger for leak down of the hydraulic fluid in the accumulator. 
     
     
         20 . The method of  claim 13 , wherein hydraulically securing the reciprocating member includes:
 pressurizing the hydraulic fluid through a first valve in a hydraulic circuit in fluid communication with the reciprocating member; and   closing the first valve in response to a force acting on the reciprocating member by the at least one valve.