Abstract:Piston slap is a major noise source of internal combustion engine. Reduce piston slap is one of the most important countermeasures to improve the noise and vibration ability of internal combustion engine. The influence of the coupled vibration of piston, connecting rod, crankshaft and engine block on piston slap is taken into consideration, and an analytical model of piston slap is developed in this paper. The piston slap induced impact force and vibration response of engine block is investigated based on present model. The effect of piston skirt profile and piston pin offset on piston slap and radiated noise of engine block is discussed. The calculate results and experiment data shown that the profile of piston skirt has a significant influence on high frequency component of piston slap induced impact force and engine noise quality, that piston pin offset to major thrust side can decrease the maximum value of piston slap force and sound pressure level of radiated noise.