Application to Engine Development of Friction Analysis by Piston Secondary Motion Simulation in Consideration of Cylinder Block Bore Distortion

Piston skirt friction has been considered to be related to cylinder block bore distortion and piston secondary motion, but it has been studied almost exclusively in isolation, and its detailed relationship to the functioning of an actual engine has not been clarified. In an attempt to improve correlation with actual engine behavior this study evaluated piston skirt performance using computer simulation of piston secondary motion that include the effects of cylinder bore distortion, skirt stiffness and skirt form. First, calculation results of cylinder block bore distortion and piston secondary motion was compared with measurement value respectively by amount of deformation and amount of secondary motion, and that validity was confirmed. Next, the technique was applied to the development of an actual engine, and the engine performance was studied along with the establishment of a method to predict friction. The application of the new simulation technique in engine development reduced friction approximately 2%, demonstrating the effectiveness of the method. Moreover, seizing was evaluated by wear load parameter at the same time, and increase in the reliability was attained.