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

摘要： 在某皮卡整车噪声、振动与声振粗糙度开发过程中，带挡加速时存在较为明显的拍击 共振异响，通过对主驾右噪声和空压机振动测试以及声源定位测试，锁定了该异响主要是由 空压机带轮-曲轴减振皮带轮之间的皮带股拍击带轮产生的，测试发现该皮带股振幅较正常轮 系超出 50%～100%以上，最大达到了 47 mm。分析了该异响的源头、传递路径，分别制定了 降低曲轴扭振、提高空压机支架安装刚度、提高空压机模态频率、提高空调管路隔振以及前 围板等声学包处理对策，最终消除了该异响并有效提升了整车声品质，车内噪声水平与竞品 车辆相当。该异响是比较典型的前端轮系皮带拍击噪声，通过该故障的分析解决，提出了前 端轮系匹配的控制参数。

关键词: 前端轮系；空压机支架模态；拍击异响