Study On Valve Train Simulation Analysis And Cam Profile Design Of JYM154FMI Engine

The valve train system is one of the most important mechanisms of internal-combustion engine, whether it's performance is good or bad, that affects the working performance and the reliability of the whole engine directly. Along with the request of the engine's high power, it demands a higher index about the valve train. The kinematics and dynamics research on valve train is one of the main active research fields about internal-combustion engine. The valve train is drived by the camshaft, so the cam design is crucial to the valve train's performance.In this paper, by taking the valve train of JYM154FMI engine as research object, the kinematics and dynamics performance are researched and the method of cam profile improvement design is discussed. In the course of studying, the kinematics model on valve train is established in professional software AVL-TYCON and multi-body system analysis software ADAMS respectively, and the kinematics performances of the valve train are calculated. The model is verified by contrasting the calculate results and test results of valve lift and valve timing (1mm valve lift). The other kinematics characteristic index such as fullness ratios and cam curvature radius are also investigated.The dynamics calculation about the valve train is made by AVL-TYCON using parametric model. The results show that the valve train run smoothly under rated speed , and the seating velocity and force are normal; There is no flying-away and valve rebound; The valve springs work normally and are not blocked. Based on the simulation and analyses of the valve train, the method of cam profile improvement design according to new valve timing is discussed; Then the valve train and engine working performance with new cam profile is simulated, and the results show that the valve train can work stably and engine high-speed performance are somewhat increased.There has been a lot of research on cam profile of the valve train at present. At the aspect of acquiring the original cam profile's approximation value through test data, most researchers use smoothing-fitting method, which is complex and may not effective sometimes. Based on research, this paper put forward a obverse and reverse unite calculation of valve train kinematics , which can reversely obtain the cam profile data more accurately according to the basic principles of poly-dynamic cam design. It has been approved that this method provides a new and effective way to obtain the original cam profile's approximation values through measurement.