Establishment and Application of Dynamic Characteristics Prediction Model for Variable Valve Timing System

To predict the dynamic characteristics of variable valve timing system at early stage of engine development, the cam phaser working process has been analyzed and a model which is used to predict system dynamic characteristics has been established by software AMESim in this paper. Using this model, we can calculate system response speed and phase precision under different engine speed, oil temperature, and oil pressure, as well as the effects of different structures and operating parameters. The conclusions are 1. system response speed and phase precision are affected significantly by the characteristics of coil spring, structural parameters, and air content in oil. 2. Within a certain range of leakage clearance, the influence of oil leakage on dynamic characteristics can be neglected. 3. Simulation data are verified by measured results. The prediction model is effective to develop and optimize the variable valve timing systems for various engines.