Study On 4-Valve Engine Valve-Train System

Valve-train not only influences the reliability of engine directly, but also does the performance of it. With the development of engine technology, there are more questions and deeply study on valve-train. Many dynamics test method and dynamics model have been applied to the research of valve-train。When we towards various dynamics model at present ,how to compare and comprehend the specialty and the serviceable range of these models, it needs farther development in the future.Based on the geometrical relation between tappet and cam, according to kinematics and dynamics basic principle, uniform formulas for mutual lift-range transition between flat based tappet, roller (or sphere) tappet and cone tappet are presented.Build the geometric model according to blueprint and topology structure of the valve-train system, then add joints, motions and loads, multi rigid body dynamics model is established by software MSC.Adams/view.Finish simulation and calculation in MSC.Adams, get dynamic parameter of the valve-train, the force status of each connection, the velocity and acceleration of all components. introduce the influence of unbalanced valves, different valve gap. Have proposed some reduction movement different methods Structural analysis of valve train has been done for the basement of dynamics evaluation. Meanwhile, also discussed the impact on valve acceleration of the bent axle rotational speed.According to the results from ADAMS, we have established several components'models in ANSYS for further analysis and calculation. We focused on the stiffness of the pushrod as well as the whole system, the stress between cam and tappet and the valve's structural analysis for the reliability proof of the system. Then measured valve system stiffness and movement of the valve, and compare the actual measurement results with the simulation results, the reliability of the system has been verified.Finally, Valve-Train system design has been optimized to reduce the imbalance and to improve the friction and wear conditions between rocker arm and valve-bridge. Some conclusion was drawn from the above analysis, providing suggestion for the design of valve-train system.