Study of Piston Slap Induced Noise and Vibration of Internal Combustion Engine (1st Report, Theoretical Analysis and Simulation)

This paper presents a calculation method of the impact force and the vibratory response of a cylinder liner induced by the piston slap in internal combustion engines. In this method, the following dynamic conditions in the collision of the piston with the cylinder liner are assumed; (a) four points of collision at upper and lower parts of the piston, (b) employment of springs and dash-pots equivalent to the dynamic stiffness of the piston and the damping effect of the oil film. Also, the equation of motion for the coupled system of piston and cylinder liner is derived, taking account of several resonant modes of the cylinder liner to simulate accurately time histories of the impact force and the response. As a practical example, the piston slap phenomenon in an actual diesel engine is analyzed, and it is confirmed that calculated time histories of the vibratory acceleration of the cylinder liner agree well with measured data.