发动机正时链传动的调制现象与声品质研究及优化

Research and Optimization on Modulation Phenomenon and Sound Quality of Engine Timing Chain Drive

发动机正时链条系统在低负荷升速工况较容易出现啸叫等噪声问题。升速时正时激励噪声通过空气辐射及悬置等结构振动传入驾驶室,引起用户抱怨,问题频率与链系统啮合阶次相关。采用仿真与试验结合的方法分析链系噪声产生机理及优化措施,由仿真分析优化并降低了曲轴低阶次的调制特征,降低了缸体缸盖传递力。试验验证静音链及降低摩擦损失方案减小了链条啮合阶次能量,使得声音更加安静和纯净。提高了产品的主观感知质量达到了可接受的NVH特性。

The engine timing chain system is prone to squeal and other noise problems under low load and speed up conditions.The noise of timing excitation is transmitted into the cab by air radiation and structural vibration of mounting,which causes users to complain.The frequency of the problem is related to the meshing order of the chain system.This paper introduces the method of combining simulation and experiment to analyze the mechanism of chain noise and optimization measures.The simulation analysis optimizes and reduces the low order modulation characteristics of crankshaft,and reduces the response and transmission force of cylinder block,cylinder head.It is verified by experiments that the silent chain and the scheme of reducing friction loss can reduce the chain meshing order energy and make the sound more quiet and pure.It improves the perceived quality of the product and achieves acceptable NVH characteristics.