Design Of The Variable Valve System Based On 468Q Engine

As the current hot in engine valve system, variable valve technology has excellent performance the fuel economy and the power. From a worldwide perspective, the development of this technology includes camshaft polarization phase shifting mechanism, mechanism of change cam profile and ultimately to achieve the full variable valve system. According to the problems of slow response in electromagnetic and electro-hydraulic control systems, a new variable valve mechanism with mechanics, hydraulics and electromagnetics has been designed based on 468 Q engine in this paper.Firstly, the typical variable valve systems of various countries is classified and studied. Combined with some companies’ design concept, the institution gets the design guide and the reference. Finally, the paper ensured the structure of this body. Among them, tappet is responsible for the control of valve seating buffer and small lift profile, and the plunge is responsible for the control of valve lift which is greater than the original.For tappet/tappet guide and tappet/plunger two systems, their working principles are the same. The calculation follows the design principle of the hydraulic cylinder. Procedure that will be implemented by the agency can be divided into the following two functions:(1) For the tappet, the oil should start flow into the tappet guide’s cavity at 20°CA before cam buffer to rise the tappet, and reach the specified location latest in the buffer period of 10°CA; before the valve seating 20°CA complete drainage work in order to sit steadily.(2) For the piston, variable valve lift adjustment should be finished 60°CA before the valve open; free oil drainage controlled by ECU starts from the top of lift, but forced oil spill must be started in 20°CA in front of the seated. According to the achievement of the effect, this paper designed the structure of EHMVA, and calculated the parameters of the hydraulic cylinders, the diameter of each hole, the size of the plunger and the selection of hydraulic pump depending on specific requirements.Finally, AVE EXCITE Timing Drive model and AMESim model are established according to the design of structure. The AMESim model is used to simulate the hydraulic control system. Based on the design, two sets of the hydraulic cylinder system has the same work principle, so this paper just build one model and the other one is only has different parameters. The AVL model is mainly used to optimize the cam profile in order to satisfy the design requirements in kinematics and dynamics. In front of the simulation of the EHMVA system, the paper reverses to fit the original cam profile and simulate it. It uses as a standard to debug the new one for the sake of overcoming the shortcomings of the institutions.In this paper, the EHMVA system is designed and simulated based on the 468 Q engine. From the conclusion, the variable valve system designed in this paper achieves the goals which are set at the very beginning.