Camshaft Position Actuator

Consisting of two major elements, the camshaft position actuator provides continuously variable camshaft-to-crankshaft timing (phasing) within a limited range of angular degrees. The sprocket housing is driven by the engine timing belt or chain. Inside the sprocket housing is the second element of the actuator, the rotor. Featuring three to four lobes, the rotor fits inside a similarly shaped cavity within the sprocket housing, creating oil chambers on either side of each lobe. At the center, the rotor is fastened in a fixed position to the camshaft.

Oil passages from the center of the camshaft provide filling or venting of the apply and return chambers. Balanced filling and venting of these opposing chambers produces a torque between the sprocket housing and the rotor. Torque on the actuator rotor changes the relative angular position (timing) between the camshaft and camshaft drive sprocket. With no oil pressure in either chamber, a torsional spring returns the rotor to base timing.