Smart Actuator for Sensorless Electromagnetic Variable Valve Actuation

Replacing the traditional camshaft of spark ignition engines by a variable valve actuation (EVA) system promises noticeable fuel savings and substantial improvement of the motor torque [1]. Up to now, all known electromagnetic EVA systems apply one bulky central electronic control unit (ECU) together with complex wiring harness. A mechatronic approach for such system, where each actuator is joint together with its own control electronics, offers substantial performance and cost benefits. Extraordinary environmental conditions arise for such mechatronic system which is directly mounted on the cylinder head of the engine. Ambient temperatures up to 125°C together with vibrations, which are generated by the impact of the armature of the electromagnetic actuator, ask for a new assembly technique of the electronic. This paper describes the systematic approach for the design of such complex mechatronic system. Simulation methods for the different mechanical, electrical and thermal aspects and their interaction will be discussed. Measured data for the different subjects and comparisons with the simulations will be presented.