关键词: 蠕行轰鸣；二阶振动；排气系统；主客观评价

Abstract: In the performance verification stage of a certain sport utility vehicle (SUV), the subjective evaluation D gear the air conditioner creeping car in the front row of the car booming obviously, and the floor is accompanied by obvious vibration, and the engine speed is about 930 r/min. Through the analysis of the measured data, it is found that there is a significant peak at the spectral curve of 31 Hz, and the playback filter listener confirms that the frequency is a problem frequency. By increasing the muffler at the exhaust tail or disconnecting the exhaust hook, the exhaust system is confirmed to be the root cause of the creeping booming. Combined with the transfer path investigation and computer aided engineering (CAE) analysis, it is finally determined that the problem is caused by the coupling of the engine's second order vibration to the 31.5 Hz vertical bending mode of the exhaust system. According to the principle of source-path-response, the scheme of adding 31 Hz absorber to the passive end of the hook at the sub-elimination place is formulated, or the engine speed of the D gear air conditioner creeping condition is increased to 1 050 r/min, and the subjective and objective evaluation of both schemes is acceptable. However, considering the performance, cost and economy of the whole vehicle, the latter is determined to be the final implementation plan.

Key words: Creeping Booming; Second order vibration; Exhaust system; Subjective and objective evaluation