Research on variable valve system based on electro-hydraulic drive

Abstract

Variable valve technique can significantly improve the performance of the automobile engine and reduce pollution emission by varying valve timing, valve duration and valve lift. Variable valve system which is based on electro-hydraulic drive has the advantages of better stability, low noise and simple structure. In this paper, a variable valve system which is based on electro-hydraulic drive is introduced. In this system, a fast response proportional pressure reducing valve is used to throttle the high-pressure and low-pressure fluid. The fluid discharged from the proportional pressure reducing valve drives the piston of the single-acting cylinder and the piston drives the valve. One valve spring is used to close the valve. Valve timing and valve lift can be controlled by varying the input signal of the proportional pressure reducing valve. The component, structure and working principle of electro-hydraulic control system are discussed in this paper respectively. The key system parameters are studied through the simulation. Finally, we carried out some experiments on the established test rig. The results of the experiment show that the system can meet the need of the engine whose maximal speed is 1500 rpm.