Analysis of advantages and of problems of electromechanical valve actuators

The electromechanical devices proposed in technical literature are very flexible. However, their working principle (fixed lift, fixed lifting time and variable valve events) imposes the use of different strategies, such as cylinder or port deactivation to enable work at partial loads. This happens in particular at low loads. The present paper aims to evaluate the effect of the design and of the strategies adopted to vary the load (cylinder or port deactivation etc) on performance and on pollutant formation of a stoichiometric DISI engine. The calculations were performed by a commercial one-dimensional code (Wave produced by Ricardo). This tool was also used to give inputs to the design of the electromechanical actuator. The electromechanical design of the actuator was carried out with the aid of the code Flux2D produced by Cedrat. This code allows the complete simulation of transients and of the electrical losses of the actuator. The system requirements of performing the first lift at engine start up and catching in normal operation were analyzed. In this way a fairly realistic picture of the main advantages and of the typical problems of Electromechanical Valve Actuators was outlined.