某大功率柴油机结构振动辐射噪声源探究

某公司研发的大功率柴油机装车后，用户反映怠速时发动机后端噪声大，并伴有“格拉拉”的异响。为确定发动机的噪声源，本文分别在台架和整车上对发动机做了振动噪声试验，试验结果显示发动机的噪声主要来自齿轮室、高压油泵和空压机以及缸盖罩壳，发动机“格拉拉”的异响是齿轮室的齿轮撞击声，造成齿轮撞击的主要原因是齿轮啮合间隙过大。对此本文提出了两种降噪方案：第一在齿轮室、高压油泵和空压机等处加装遮蔽罩；第二改进齿轮和缸盖罩壳设计，减小齿轮啮合间隙和缸盖罩壳耦合振动，降低噪声。

Study on the radiated noise source from structure vibration of a large power diesel engine

Big noise and rattle was annoyed at idling work by vehicle users when a new type large power diesel engine which was researched and developed by a domestic company was assembled to vehicle. Vibration and noise tests were performed in test-room and on vehicle separately in order to locate the noise source. The results of tests show that the noise mainly stem from the gear-housing, high pressure oil pump, air compressor and valve cover. The rattle from the gear-housing was the knocks which were because of the over-big clearance between two gears when gears mesh. At last two ways of reducing noise were proposed, one is that shield were assembled around the gear-housing, high pressure oil pump and air compressor, the other is to redesign and optimize the stepped-gear and the bolts of the valve cover to reduce the knocks of gears and the couple vibration of the valve cover and reduce the noise.