Prediction and validation of dynamic characteristics of a valve train system with flexible components and gyroscopic effect

Abstract

Flexibility and inner stress of transmission components are main considerations in the development of high-precision and lightweight engines. Gyroscopic effect of rotary shaft and rotor should also be considered in high-speed engines. Therefore, an elastic dynamic model of a valve train system is proposed. The model includes multiaxial flexibilities of camshaft and linkages, gyroscopic effect of the camshaft and cam rotor, centrifugal force of cams and friction force and moment of the cam–tappet pair. Then, the natural frequency, mode shape, pushrod stress and housing vibration are predicted using the proposed model. Results show that the gyroscopic effect of the rotors and camshaft apparently affects the natural frequency of the system by changing the camshaft stiffness. The proposed model can effectively predict the dynamic stress, as proven by a stress experiment. In addition, idling and maximum working speeds are recommended using the predicted model and verified by a vibration experiment. Thus, the proposed model can be an important reference in engine adjustment, improvement of component durability and determination of idling and maximum speeds.