Analysis of Structural Strength in Diesel Engine Electro-hydraulic Variable Valve Timing System

Finite element method was used to analyze and compare the components and parts structural strength of initial valve system and variable valve timing system. In addition, nominal tension stress method was used to calculate the life of components and parts. The result shows that the part and components' stress of variable valve timing system increases a little compared with initial valve system when the load is maximum steady pressure, and the maximum stress is in tappet component, which increases 20.2% compared to the initial system. When the load is maximum fluctuation pressure, the maximum pressure in tappet component increases 127.4% compared to the initial system but is still much smaller than yield strength, which means the design satisfies the requirement of static stress. Additionally, Goodman and Gerber equation were used respectively to describe the relation of stress amplitude and average stress. The result shows that the stress amplitude for all components and parts is smaller than the relative materials' fatigue strength and the life of components and parts satisfies the requirement of infinite life.