Abstract: The apparatus of the present invention provides a lash adjuster feed channel for an engine assembly. The engine assembly includes first and second sets of hydraulic lash adjusters responsive to a variation in hydraulic fluid pressure to cause a variation in lift of first and second sets of engine valves respectively operatively connected thereto. The cylinder head defines a first feed passage in fluid communication with the first set of hydraulic lash adjusters, and a second feed passage in fluid communication with the second set of hydraulic lash adjusters. The valve lift of the first set of engine valves is independently variable by controlling the transfer of hydraulic pressure in the first feed passage, and the valve lift of the second set of engine valves is independently variable by controlling the transfer of hydraulic pressure in the second feed passage. A corresponding method is also provided.

Abstract: A method for diagnosing malfunctions of switching valve lifters includes sensing variations in pressure of trapped oil in a drive chamber of a hydraulic camshaft drive, such as a cam phaser, comparing peak oil pressure readings in the drive chamber resulting from the increased torque of opening the valves of various cylinders of an engine and identifying cylinders having lower than normal valve opening pressure readings, indicating failure of an associated valve lifter to properly actuate a valve of the cylinder. Apparatus for indicating such malfunctions could include a cam phaser with pressure chamber, a pressure sensor connected to indicate pressure variations in the chamber; and a pressure indicator connected to the sensor and adapted to indicate actual pressure variations for comparison with normal variations to identify low pressure peaks indicating malfunction of a switching lifter. A computer could be used to receive and act upon the malfunction indications.

Abstract: The invention provides a valvetrain configuration in an internal combustion engine in which a plurality of two-step rockers enable the engine poppet valves to switch between two lift profiles. In addition, a lost-motion stationary lash adjuster enables the deactivation of the engine poppet valve. The integration of a two-step rocker with a deactivating stationary lash adjuster yields a better control of the combustion process, under different engine operating conditions than what is achievable with either one of these actuators acting alone. Preferably, the locking and unlocking of the two-step rocker arm and deactivating stationary lash adjuster is controlled by two on/off hydraulic valves in a hydraulic circuit, and a piloted check valve prevents hard landings between stationary and moving components within the stationary hydraulic lash adjuster.