货车怠速工况下噪声源识别及其控制

为了消除货车怠速工况下出现的异常噪声，利用声强法和消去法进行了噪声源识别，结果表明：噪声主要频率范围为288～344 Hz，进气口空气辐射噪声和空气滤清器壳体表面辐射噪声是其主要噪声源，空气压缩机是其根本来源。在此基础上，提出了在空气压缩机进气管道中增加扩张式进气消声器的改进措施，基于有限元方法的进气系统传声损失分析结果和消声器样件的实际装车试验结果均表明：消声器具有良好的降噪性能，增加消声器后，典型测点的噪声在25～1 600 Hz频带范围由77.48 dBA降低至73.21 dBA。异常噪声被有效消除，声品质得到明显改善。

Noise source identification and noise abatement of truck under idle speed condition

In order to eliminate the obviously abnormal noise of truck under idle speed condition, the noise source was identified based on sound intensity method and source separation method. The results showed that intake orifice and shell surface of air cleaner were dominant radiation sources whose frequency range from 288 Hz to 344 Hz, and root of noise source was the air compressor. The modification that expansion muffler was added into air compressor intake system was put forward. The analysis results of transmission loss of air compressor intake system based on finite elements method showed that the muffler could fulfill the requirement. Furthermore, experiment results of modified vehicle showed that the noise range from 25 Hz to 1 600 Hz at the typical measurement point had been reduced from 77.48 dBA to 73.21 dBA. The abnormal noise is eliminated and the sound quality is improved obviously.