Mechanical Simulation Research On Variable Compression Ratio Piston

VCR (Variable Compression Ratio) technology can improve the low load's performance of engine effectively. Using dynamic simulation software ADAMS combined with finite element analysis software ANSYS, this paper establishes the simulation model for a technical solution of VCR piston, and determines the boundary conditions of the VCR piston model. The VCR piston dynamics simulation model has been validated against the static simulation experiments and dynamic response simulation experiments of the real VCR piston. Many projects of VCR piston dynamics simulation analysis have been completed, and the simulation results show the technology solution of The VCR piston, which has been researched by this paper, is feasible.In the processing of the dynamic simulation model of VCR piston, the rigid body displacement among the various parts is simulated by means of ADAMS, and a flexible disk spring of the 3D body model is built by using the finite element software ANSYS in order to simulate the contact between the disc spring and the ball with considering the influence of the contact point on the stiffness of the disc spring. Coupling ADAMS with ANSYS, the simulation model of VCR piston can reflect the actual situation of VCR piston more truly. This paper also presents a new modeling method for the solution of symmetric problems when coupling ADAMS with ANSYS.According to the actual assembly of various components and the room of the VCR piston mechanisms, the overall structure of the constraints and the contact relationships among the various components in the ADAMS are defined. The contact parameters are set up based on material properties and the condition of contact. In order to verify the correctness of the piston VCR simulation model, the corresponding mechanical boundary conditions have been established according to the experimental conditions of both static simulation tests and dynamic simulation test. The mechanical boundary conditions of engine have also been set up to simulated VCR mechanism at engine working conditions. Static loads were exerted on various structural concepts of the actual VCR mechanism and the elastic elements by using a hydraulic universal tester during static simulation experiments. Dynamic simulating loads were exerted on actual VCR pistons by MTS tester. The simulating model of VCR piston has been validated feasibility against the test results.With the dynamic simulation model of the VCR piston, Schemes of VCR piston of 135 non-supercharged diesel engine dynamics simulation have been calculated. The pressure in cylinder exerted on the piston is provided by the simulation of the engine performance. The influence of the speeds, loads, the moving mass and structure parameters on the mechanical property and dynamic response of the VCR piston have been analyzed. The results show that the proposed VCR piston has well dynamic response, which can meets the requirements of the anticipant design.