降低柴油机噪声的措施及评价

对一台多缸柴油机进行噪声源识别及各种降噪措施和降噪效果的评价．通过表面振动识别,找到了噪声辐射的主要部件,并通过近场扫描加以验证．针对现有柴油机的燃烧状况,对供油提前角进行了调整,降低了燃烧噪声．通过加装扭振减振器,使得曲轴扭振明显减小,整机噪声下降了1．5 dB(A)．改进油底壳和加装橡胶减振垫使柴油机辐射噪声分别降低了0．85 dB(A)和0．4 dB(A)．综合以上各种方法,使得柴油机整机噪声水平降低了 2 dB(A),低于国家标准要求,说明所采取的降噪措施切实可行．

Noise Reduction Measures and Evaluation of Diesel Engine

Some methods were adopted to reduce the noise of diesel engine, and the effects of them were evaluated. Firstly, the main part of surface radiated noise was found with surface vibration technique,and it was verified by the experiment of near-field scanning. By modifying the advance angle of fuel supply, combustion noise was reduced. In order to reduce torsional vibration of the crankshaft, some newly-designed torsional vibration dampers were applied to the free-end of crankshaft and engine noise was reduced by 1. 5 dB( A) . By setting rubber damping pad and altering shape of oil pan, radiation noise was also reduced by 0. 85 and 0. 4 dB( A) respectively. The results indicate that sound power level (PWL) of the engine is reduced by 2 dB(A)with the proposed measures, which makes it lower than the value of the national standard. So the measures are effective and available.