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

摘要： 某运动型多用途汽车（SUV）在整车性能验证阶段，主观评价 D 挡开空调蠕行行驶车 内前排轰鸣明显，且地板伴有明显振动，发动机转速约 930 r/min。通过分析实测数据发现， 频谱曲线 31 Hz 处存在明显峰值，回放滤波听音确认该频率为问题频率。通过排气尾口加大消 声器或断开排气吊钩，确认排气系统为引起蠕行轰鸣的根本原因。结合传递路径排查和计算 机辅助工程（CAE）分析，最终确定该问题是由发动机二阶振动与排气系统 31.5 Hz 垂向弯曲 模态耦合引起的。根据源-路径-响应原理，分别验证在副消处吊钩被动端加 31 Hz 吸振器方案， 或将 D 挡开空调蠕行工况发动机转速提升至 1 050 r/min 方案，主客观评价两种方案均可接受。 但综合考虑整车性能、成本和经济性等，确定后者为最终实施方案。

关键词: 蠕行轰鸣；二阶振动；排气系统；主客观评价