关键词: 前端轮系；空压机支架模态；拍击异响

Abstract: During the noise, vibration, harshness development of a pickup truck, there is an obvious slap abnormal noise when accelerating. Through the measure of the driver's right-ear noise and air compressor vibration, as well as the sound source location test, it is locked that the abnormal noise is mainly the air compressor. The belt between the pulley and the crankshaft vibration damping pulley slapped the pulley to produce abnormal noise. The test found that the amplitude of the belt vibration was more than 50%～100% higher than that of the normal car, and reached to 47 mm. The source and path of the abnormal noise were analyzed, and the acoustic treatments such as reducing the torsional vibration of the crankshaft, improving the installation rigidity of the air compressor bracket, increasing the modal frequency of the air compressor, improving the vibration isolation of the air conditioning pipeline and the sound package of the front wall were tested respectively. Finally, the abnormal noise is eliminated and the sound quality of the whole vehicle is effectively improved. The sound pressure level in the car is equal to that of competing vehicles.The abnormal noise is a typical front-end gear belt slap noise. Through the analysis and solution of the fault, the control parameters of the front-end gear train matching are proposed.

Key words: Front end accessory drive; Air compressor bracket constraint modal frequency; Slap abnormal noise