内燃机整机结构修改的声学评价

Evaluation on the Structural-Acoustic Modification of Internal Combustion Engines

为准确预测内燃机结构声辐射,并为设计提供对比研究方案,采用有限元法和边界元法(FEM/BEM)联合求解数值仿真技术,建立了一种四缸柴油机结构声辐射模型,得到了整机模态、表面振动速度、辐射声功率、声辐射比和测点声压的结果.在此基础上,探讨了4种结构修改方案的声辐射情况.主要声学量的对比表明,油底壳侧板波浪型设计、主轴承座横向螺钉连接及平衡架对噪声的减低有显著作用.

To improve the accuracy of prediction in the simulation of the dynamic and acoustic behavior of engines, and offer selective projects, an approach based on the coupled FEM/BEM method is proposed. Prediction models of a certain 4 cylinder diesel engine were established. Results of prediction including vibration modes, surface vibration velocity, radiation power, radiation ratio and field pressure were obtained. Based on these results, four projects were investigated and the effect of modified engine structures was analyzed. Comparison between the original model and several modified models showed that the wavy-ribs in the oil sump, the main bearing cap connected by transverse bolts, and the bracket of balance structure proved to be excellent in reducing the engine＇s structural noise.