2.4L汽油机噪声及其频谱特性的影响因素分析

摘要

The noise levels of two sample engines A and B with the same structures but different materials are analyzed and compared.The main factors that affect the noise spectrum of engine A are analyzed, and the main noise source and the measure to reduce engine noise are investigated.It is found that the fundamental vibration related to the ignition frequency and the radiation noise from the surface of the inlet and exhaust sides of the engine are the main noise sources.The concentration of gasoline mixture and ignition timing influence the combustion noise in the medium and high frequency range, but do not affect the fundamental frequency.The higher the engine speed is and the heavier the load is, the higher the peak value of fundamental frequency is.Thus, improving the structural stiffness, synchronous control of the cylinders and reducing the crank’s vibration are the effective measures for reducing the noise level of the entire engine.%在对结构相同但材质及工艺不同的A、B两台样机进行噪声水平对比分析的基础上,着重分析影响样机A噪声频谱特性的主要因素.结果表明:与着火频率相关的发动机基频振动和进排气侧表面的辐射噪声是主要噪声源;而混合气浓度以及点火时刻虽影响中高频范围的燃烧噪声,但对基频成分无影响.转速越高、负荷越大,基频峰值越高.因此,改善进排气系统的结构刚度、各缸均匀化的控制策略以及曲轴的减振是降低整机噪声水平的有效措施.