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本文介绍的是五十铃汽车公司在一台声响有改善的柴油机上对辐射噪声的机理研究所完成的最新结果。该发动机总噪声级与按传统设计者相比是相当低的。这是由于结构的改进在声学重要区域的800～1200Hz内的噪声已经充分减小,但目前在315Hz和1600Hz的1/3倍频程处出现两个主要波峰,对总噪声起着支配作用。为进一步降低发动机的噪声,这两个波峰值必须予以充分减小。因此对在315Hz处噪声发生的机理,既要在运行的发动机上、也要在实验发动机上,采用模态分析程序以及理论分析的方法详细地研究。上述研究揭示了曲轴箱振动特性和曲轴扭转振动之间的关系。此外还介绍了减小噪声波峰值方法的研究结果。
This article presents the latest results from Isuzu Motors’ study of the mechanism of radiated noise on a sound-improving diesel engine. The total noise level of the engine is quite low compared to conventional designers. This is due to structural improvements that have substantially reduced the noise in the 800-1200 Hz region of acoustical importance, but at present there are two main peaks at 1/3 octave of 315 Hz and 1600 Hz, which dominate the overall noise. To further reduce the engine noise, these two peaks must be sufficiently reduced. Therefore, the mechanism of noise occurring at 315 Hz should be studied in detail on both the running engine and the experimental engine using the modal analysis program and the theoretical analysis. The above study reveals the relationship between the crankcase vibration characteristics and crankshaft torsional vibration. In addition, the research results of the method of reducing the noise peak are also introduced.