Optimization of timing drive system design parameters for reduced engine friction

A timing drive model was developed based on computer-aided simulation methods and used to calculate the contribution of each system component to the overall timing drive friction loss at various engine operating conditions. Combining the analytical results and statistical methods, an optimization study was performed to calculate the ideal system design parameters such as hydraulic tensioner spring force and flow rate, sprocket tooth profiles and circularity, and oil supply pressure. The simulation results revealed that while the plastic guide - timing chain friction is responsible for the most part of the frictional losses, the contribution of timing chain friction increases with increasing speed. It was found that the tensioner guide is the key element in the guiding system that causes friction losses. Furthermore, tensioner spring force and engine oil pressure were identified as major design parameters that influence the efficiency of the timing drive. Consequently, the simulation results showed that 20 % improvement in friction loss could be obtained in the overall timing drive by simply optimizing the design parameters.