针对某车型(开空调)在发动机怠速、冷却风扇高速运转时,方向盘产生振动和噪声的问题,经试验找到了方向盘怠速振动的主要原因.运用锤击法,测量整车状态下方向盘的固有频率,对于主要的激励源冷却风扇则采用扫频法,测量出冷却风扇的固有频率.分析得出发动机怠速时,方向盘振动的主要原因首先是发动机二阶点火频率引起的共振,其次是冷却风扇固有频率与冷却风扇壳体的固有频率以及冷却风扇激励耦合产生的共振.在保证风扇冷却性能和成本因素的前提下,采用提升冷却风扇固有频率和锁定冷却风扇最高转速的改进方案,取得了良好效果. Aiming at the problem that a certain type of vehicle (open air conditioner) produces vibration and noise of the steering wheel when the engine idling and the cooling fan runs at high speed, the main reason of the steering wheel idling vibration is found through the test. Using the hammering method, the natural frequency of the steering wheel , The main excitation source cooling fan sweep frequency method was used to measure the natural frequency of cooling fan analysis of the engine idling, the main reason for the steering wheel vibration is the resonance caused by the second-order ignition frequency of the engine, followed by the cooling fan inherent Frequency and the natural frequency of the cooling fan housing and cooling fan excitation coupling resonance in ensuring the fan cooling performance and cost factors under the premise of using the cooling fan to enhance the natural frequency and cooling fan maximum speed of the improved solution and achieved good results .