A Study on the New Numerical Calculation Method of Dynamic Characteristics and Simulation Model for Internal Combustion Engine Valve Train System : Especially, Cam Lift, Acceleration and Jerk Curves of New Designed Cam Profiles

Runge-Kutta-Gill’s method has been widely used for the dynamic motion numerical calculation of the internal combustion engine valve train system. This paper refers to a new simulation method of the valve train dynamic motion using the transition matrix method. This is a kind of step by step numerical calculation method, making indirect use of Taylor series. As the numerical calculation in this method are made, taking into consideration the constant coefficients in the equation of motion, it has the advantage that the time required for making numerical calculations can be so much reduced. And, to evaluate the new simulation method, we compare the simulated results with the measured data. The numerical calculated results is shown to agree sufficiently with the measured results. Next, to investigate the valve train dynamic characteristics, we change the shape of the cam profile, especially the shape of the cam lift-acceleration (jerk) curve as the numerical calculation conditions, and simulate the dynamic motion of each cam profile using both Runge-Kutta-Gill’s method and the transition matrix method in the same equivalent model of the valve train system. The numerical calculated results by the two method almost agree. Also, it is shown that the abnormal behavior of the valve train dynamic motion can be sufficiently reduced. As the conclusion, it is shown that the transition matrix method can be used such a useful tool as Runge-Kutta-Gill’s method to numerical calculate the valve train dynamic motion, and that the suitable change of the cam lift-acceleration (jerk) curve of the cam profile can effectively reduce the abnormal behavior of the dynamic motion in the internal combustion engine valve train system from the analytical viewpoints. The validity of this method was confirmed by comparing and examining the measurement results and the simulation numerical calculation