Valve-Train Dynamics Calculation, Model Simulation and Actual Testing for Friction Reduction to Improve FE

Valve train system is one major contributor to engine overall friction loss and is approximately 30% of total engine friction at lower speed and approximately 20 % at higher engine speed. Valve spring loads (preload and working) are proportional to friction loss of valve train. To optimizing the valve spring design main requirement is valve train perform it function safely at maximum engine cutoff RPM with minimum preload and working load. Robustness and frictional power loss are contradicting requirement, robustness demand high stiffness spring for better valve jump and bounce performance with dynamic safe valve spring design, on the other hand low frictional power loss demand for use of low stiffness spring. To optimize the valve spring stiffness for meeting both the requirement we need accurate prediction of valve spring in design stage and good correlation with testing data to reduce the number of iterations. For achieving robust valve spring design with low friction in current work valve Jump, valve bounce, valve spring dynamic stress and valve surging phenomena of valve train predicted from Multi body dynamic analysis is correlated with testing. Testing measurement methodology explained with test rig setup procedure. Good correlation is achieved in analysis and testing. Major evaluation parameters considered for valve spring analysis verification are valve jump, valve bounce, dynamic stresses and fatigue life performance.