Camshaft Position Actuator System

The camshaft position actuator system is an electronically controlled and hydraulically actuated system. The camshaft position actuator system enables the engine control module (ECM) to change camshaft timing of all four camshafts hydraulically while the engine is operating.

Two camshaft position actuator magnets, one for each camshaft position actuator oil control valve, are mounted to a camshaft position actuator housing on the front of each cylinder head. The ECM energizes the camshaft position actuator magnet in order to create a magnetic field. The magnetic field created by the camshaft position actuator magnet pulls, from the home position, the spring loaded spool valve in the center of the camshaft position actuator oil control valve. The camshaft position actuator oil control valve is incorporated into the fastener that bolts the camshaft position actuator to the camshaft. Alignment between the camshaft position actuator magnet and the camshaft position actuator oil control valve is crucial. An air gap must be maintained between both components.

Oil under pressure is supplied to the front camshaft bearing cap and flows through passages into the camshaft front journal. The camshaft front journal passages supply oil to the camshaft position actuator oil control valve. The camshaft position actuator oil control valve supplies oil to the camshaft position actuator. The camshaft position actuator oil control valve incorporates a return spring in order to return the internal spool valve to the home position.

The camshaft position actuator contains an inner rotor with vanes bolted to the camshaft and an outer housing incorporating the timing drive chain sprocket and camshaft position sensor trigger wheel. Internally the camshaft position actuator contains a spring loaded locking pin that prevents movement between the inner rotor and outer housing and keeps the camshaft position actuator in the home position. The locking pin releases when proper oil pressure reaches the camshaft position actuator. The exhaust camshaft position actuators also incorporates return springs in order to return the exhaust camshaft position actuators to the home position when the engine is turned off. Due to rotation direction of the intake camshaft position actuators return springs are not necessary.

Oil directed by the camshaft position actuator oil control valve's position is used to vary the advance or return of the camshaft position actuator's vanes from the home position.