The camshaft is continuously adjusted in a closed control loop. Typical phasing ranges are between 40 and 60° crank angle. The angle to be set is stored in a data map in the engine management system. Adjustment is carried out hydraulically using the engine oil system by means of an electrically activated solenoid. The angular position of the camshaft is measured and fed back to the control unit by means of a trigger disc arranged on the camshaft or the phasing unit.
Camshaft phasing units can, depending on the engine design, be mounted on both the intake and the exhaust camshaft. In SOHC engines, all timings are adjusted together.
The camshaft phasing unit allows optimum setting of valve timings based on the parameters of engine load and speed. Depending on the engine concept and number of phasing units, a significant reduction in fuel consumption and exhaust emissions as well as an increase in power and torque can be achieved.