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The electromagnetic valve actuator (EMVA) is considered a technological solution for decoupling between crankshaft and camshaft to improve engine performance, emissions, and fuel efficiency. Conventional EMVA consists of two electromagnets, an armature, and two springs has been proved to have the drawbacks of fixed lift, impact noise, complex control method and large power consumption. This paper proposes a new type of EMVA that uses voice coil motor (VCM) as electromagnetic valve actuator. This new camless valvetrain (VEMA) is characterized by simple structure, flexible controllable and low actuating power. VCM provides an almost flat force versus stroke curve that is very useful for high precision trajectory control to achieve soft landing within simple control algorithm.

In vehicle application, most of time gasoline engines are part load operated, especially in city traffic, part load operation covers most common operation situations, however part load performances deteriorate due to pumping losses and low thermal efficiency. Many different technologies have been applied to improve part load performances. One of them is to adopt over-expanded (Atkinson/Miller) cycle, which uses late/early intake valve closing (LIVC/EIVC) to reduce pumping losses in part load operation. But over-expanded cycle has an intrinsic drawback in that combustion performance deteriorates due to the decline in the effective compression ratio (CR). Combining with high geometry CR may be an ideal solution, however there is a trade-off between maintaining a high CR for good part load fuel consumption and maintaining optimal combustion phasing at higher load.