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An alternative approach to a camless SI engine with a fully variable valve train is a topology where the intake side of the valve train is equipped with electromagnetic actuators and the exhaust side is driven by a camshaft. This approach is reasonable since the most advantages of a variable valve train, like fuel efficiency, lower emissions and higher torque at low rpm, result from the variable valve timing on the intake side only. Furthermore, the most serious obstacles for electromagnetic actuators arise on the exhaust side. For instance, exhaust valve opening requires a higher actuator force to overcome combustion pressure. This becomes even worse for turbocharged engines. An electromagnetic intake valve train (EIVT) approach with a camshaft on the exhaust side is detached from the severe constraints resulting from the high gas forces on the exhaust side. In this paper the design of a dedicated intake actuator for electromagnetic valve trains will be presented.

Engine efficiency and environmental issues have increased the need for high performance engine parts. Of significant importance is the moving mass of the valve train components. Lower masses reduce inertia and this reduces friction losses. New technology inquiries from customers, market competition, possible weight reductions of 20-50%, and the ability to withstand increased operating temperatures by 100-150°C, have increased the need to develop high performance automotive engine valves at competitive costs. Lightweight hollow valves could be mentioned as one of the major targets for the development work. Achieved goals can directly be translated into lower engine working temperature or higher compression ratios for conventional engines. Also, there is a close cooperation between TRW's development and design teams of the lightweight valve project and the electromagnetic valve actuation programs (EMVA).

Electromagnetic actuators for electromechanical valve trains are highly nonlinear devices. The understanding and knowledge of their dynamics are essential for a proper use in such application. In this paper, a simple, yet comprehensive model is used to examine the effect of eddy currents on system dynamics. Furthermore, a voltage driven finite element model is established, which implements the nonlinear magnetic material properties with a modified Weibull distribution. Switch-off experiments with an electromagnetic actuator are carried out and the results are compared with the finite element simulations.

This paper describes a new way to locate the position of the combustion process in a spark-ignited engine. This method uses a characteristic value which is calculated from indicated high pressure (Pmax). This calculation requires much less time than traditional methods and allows the on-board-management (OBM) system to predict misfire cycles, and therefore, to avoid them. The new characteristic value correlates closely to given percentages of the rate of converted energy, and has been tested using high relative air/fuel ratios (λ), high rates of exhaust gas recirculation (EGR), and different fuels. Use of this method in the OBM system allows extremely sensitive adjustments of ignition timing (αIG), which maximize efficiency and minimize pollutant emissions.