Abstract:

The vehicle will generate an abnormal noise problem under the condition that the air conditioning is turned on and the engine speed is about 2400r/min. The possibility that compressor body generates excessive vibration or transfers excessive vibration through tube was ruled out by experiment. Then, through the transfer function test and the modal analysis of the engine suspension bracket, it is found that the working frequency of the air compressor is close to the first natural frequency of the engine bracket. Their resonance is the fundamental reason leading to the problem. By improving the structure of the bracket, its first natural frequency keeps away from the working frequency of the compressor. The improved scheme is tested and the result shows that the abnormal noise reduces obviously. This study method may be significant to improve the abnormal noise of the same kind.

摘要：

某车型空调开启后，发动机转速升至2 400 r/min附近时车内产生明显的异响声。试验排除了压缩机本体振动过大、压缩机振动经空调管路放大的可能性后，通过传递函数测试及发动机悬置支架模态测试，确定右悬置支架的一阶固有频率与压缩机在该工况下的工作频率耦合产生共振，是导致车内产生异响声的根本原因。通过改进支架结构提高其一阶固有频率，避开了常用转速下压缩机的工作频率范围。将改进后的悬置支架装车验证，结果表明车内异响得以明显改善。这种研究方法对改善同类汽车异响问题具有重要的实际意义。

关键词: 声学, 车内噪声, 压缩机, 传递函数, 耦合共振