Valve Cam Design And Optimization Of Chery 473F Gasoline Engine

The power performance, economic performance and emission performance of the engine is determined by the valve-train system. And so does the reliability and durability of the engine. At present, it is a trend that the power and speed of the engine becomes higher and higher. And requiring them working smoothly and reliable in high-speed operation conditions. So that it makes higher requirement to the valve-train system. The contour is the core part of valve-train system. It is usually optimize the contour to improve the performance of valve-train. In this way, the performance requirement of the engine is satisfied. So that, the simulation calculation way of the matching relationship between the contour and the engine performance becomes an important method to optimize the valve-train system.In this paper, with looking up a lot of information in home and abroad, a comprehensive technology of the engine valve-train system is summarized. And detailed analysis of kinematics and dynamics are made out. And so does the evaluation index of the valve-train system. With the application of AVL EXCITE Timing Drive software, the kinematics and dynamics model of the gasoline engine valve-train system is established for this project. And a calculation and analysis is carried out. In this way, the original valve-train system problems are found out. Based on the company's requirement to the engine, the contour of the valve-train system is optimized. Finally, with the help of the GT-POWER software, the performance of the engine is calculated again. And find that the nominal power and maximum torque of the engine are improved and reach the target requirements. The mainly work in this paper include:(1) With the application of AVL EXCITE Timing Drive software, the kinematics and dynamics model of the gasoline engine valve-train system is established. Through the simulation of the original, we find that the opening and closing of the intake and exhaust valve is not quick enough. And the lift plump coefficient and time section modulus is low. It is bad to improve the charging efficiency. The jump value of the intake and exhaust valve is too large. So the valve-train system is not working smoothly enough. The contact stress between the camshaft and rocker roller is too large. So the wear is improved. The lubrication coefficient is too small. So the liquid dynamics lubrication condition is not ideal. From this point, the measures and approaches of the design of gas cam contour is put out.(2) The simulation analysis of the valve-train system, according to specific problem, puts the cam contour optimal design scheme forward. And redesigned the intake and exhaust cam contour. Adopt new design of cam contour, the characteristics of kinematics and dynamics of the valve-train system is improved. And the problems in the original engine are solved.(3) With the help of the GT-POWER software, the performance of the engine is calculated again. And find that the nominal power and maximum torque of the engine are improved and reach the target requirements.