Variable Valve Timing Actuator: Description and Operation

Camshaft Control With Valve-lift Adjustment (VarioCam Plus)

The requirements imposed on engine design with regard to customer requests for higher performance combined with improved driving comfort, compliance with emission regulations and reduced fuel consumption give rise to conflicting design criteria. The development of VarioCam Plus was therefore based on the idea of producing a variable engine, which can be optimized for maximum performance and also for regular driving in city traffic or on secondary roads. A control system for the intake camshaft to vary the opening and closing times in combination with a valve lift system is necessary.







Camshaft actuator

The camshaft control principle is based on the principle of a vane controller. The adjustment range is 40° crank angle. The control unit determines the current position of the camshaft in relation to the crankshaft (actual angle) on the basis of the speed sensor signal and the Hall sender signal. The position control in the control unit receives the desired nominal angle via the programmed map values (speed, load, engine temperature). A regulator in the Motronic unit activates the 4-way proportional valve according to the desired adjustment when there is a difference between the nominal angle and actual angle.