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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.

Even though air compressors for traditional vehicles and fuel cell vehicles (FCVs) share many similarities, a fuel cell vehicle cannot directly employ the effective and mass-produced traditional vehicles' air compressors. This is because the fuel cell vehicles have special requirements, such as oil free, low flow rate with high pressure ratio, high efficiency, and low weight and volume. In order to find suitable air compressors to match the fuel cell system (FCS)'s requirements, different air compressors' performance and physical characteristics are compared. These air compressors include screw compressor with expander, roots compressor with expander, turbocompressor, and scroll compressor with expander. The comparison and analysis is both theoretical and practical. Results show that the turbocompressor and the roots compressor/expander have higher performance compared to the others in the aspects of input power, system efficiency, weight, and volume.