某商用车怠速油底壳异响问题分析研究*

针对产品开发过程中某柴油车型发动机油底壳怠速时“呜呜”异响问题,通过噪声与振动的测试及仿真分析,对油底壳异响原因进行分析。结果表明,怠速时机油泵的工作激励频率与油底壳模态频率耦合,形成“呜呜”声,并通过油底壳表面辐射出来。进一步实验研究表明,随着机油温度的升高,机油泵功率、工作激励幅值会逐步减小,异响逐步减小。同时实验研究表明,机油量对油底壳模态频率有影响,油底壳内机油加注量越多,油底壳模态频率越低,油底壳表面振动幅值及异响均逐步减小。针对该异响问题,明确该发动机机油加注上限及下限时油底壳对应频率范围后,通过优化怠速转速,提高油底壳模态频率等使机油泵激励频率与油底壳模态频率避频,解决了该异响问题。

Analysis and research on abnormal noise of idle oil pan of a commercial vehicle

In order to solve the problem of "whine" abnormal noise of the engine oil pan at idle speed of a diesel model in the process of product development, the cause of abnormal noise of the oil pan was analyzed through noise and vibration test and simulation analysis. The results show that the working excitation frequency of the oil pump at idle speed is coupled with the modal frequency of the oil pan, forming a "whine" sound, which radiates through the surface of the oil pan. Further experimental research shows that with the increase of oil temperature, the power and working excitation amplitude of oil pump will gradually decrease, and the abnormal sound will gradually decrease. At the same time, the experimental research shows that the oil quantity has an influence on the oil pan mode. The more oil filling in the oil pan, the lower the oil pan mode, and the vibration amplitude and abnormal sound of the oil pan surface gradually decrease. In view of the abnormal sound problem, the corresponding frequency range of the oil pan when the upper and lower limits of the engine oil filling are defined, and the frequency avoidance of the oil pump excitation frequency and the oil pan mode frequency is solved by optimizing the idle speed and improving the oil pan mode.