Research On Moving Magnet Type Electromagnetic Valve Actuation Used In Internal Combustion Engine

At present, energy saving, high efficiency and low emission are becoming the direction of vehicle internal combustion engine. Valve phase directly relate to the engine performance. The traditional internal combustion engine is subject to mechanical cam and can not achieve high freedom adjustment of valve phase. Valves are derived directly by electromagnetic actuations (EMVA). Camshafts and subsidiary structures are eliminated, capable controlling valve in maximum degree of freedom.In this paper, traditional electromagnetic valves were analyzed in detail and the inherent shortcomings were recognized. A novel moving magnet type electromagnetic valve actuation with internally placed permanent magnets was proposed in the paper. New EMVA mover could be held in the limit positions on the magnetic force generated by permanent magnets, so energy consumption is reduced. Because of its structural characteristics, new EMVA is equivalent to permanent magnet DC linear motor when moving, and control the valve movement quickly by changing current. This method overcomes the shortcomings of large energy consumption in traditional EMVA. The weak point that traditional EMVA could not be controlled effectively with large air gap after the armature away from the solenoid was solved.Engine electronic control unit, containing electromagnetic valve control unit was described and the role of electromagnetic valve control unit was highlighted. The design principles of new EMVA were analyzed and designs of the key parts were given. The complicated magnetic fields were co-produced by the moving permanent and the coil. The magnetic circuit was analyzed qualitatively in operating cycle. By using the professional software of finite element analysis, the static magnetic field of new EMVA was analyzed. The electromagnetic field, the electromagnetic force and the inductance were calculated. The three important parameters were analyzed to provide basis for control strategy.The subsystem models, including machine model, circuit model and magnetic model, were analyzed in depth and the mathematical model of new EMVA was built. According to the operation characteristics of the permanent magnet DC linear motor, the hardware of main circuit and controller circuit were designed. When solenoid valve was unlocked, double-loop control strategy was adopted, which contains inner current loop and outer energy loop. The control systems were simulated in Simulink. The results showed the reasonable of moving magnet type EMVA with built-in permanent magnets and the practical of control strategy.