通过各种噪声源识别方法，得出ZH1130单缸柴油机齿轮室罩的辐射噪声是其主要噪声源之一。通过频谱分析和模态分析获得其噪声辐射的关键模态，然后利用拓扑优化的方法对其内部的加强筋进行了重新设计及布置。优化目标是第1阶约束模态频率最大化，约束函数为整体质量约束，设计变量为室罩内部可设计区域。重新设计后，部件的第1阶约束模态频率提高了241Hz。最后，测量安装有新室罩的整机九点声压及表面振动速度，结果表明，表面振动速度曲线在关键模态频段上有明显降低，齿轮室罩侧第七点的声压级与原设计相比降低了1.2 dBA。

The gears-cover was the main noise source of the ZH1130 single cylinder diesel. The critical modal was got using the modal analysis method combined with the frequency signal analysis, and then the ribs redesign was carried on using the topology method. The objective was the frequency maximum of the 1st modal; the constraint was the mass, and the variable was the design area. After the optimization, the 1st modal frequency increases by 241Hz. Finally, the experiment on the new gears-cover was operated, and the results show that the vibration velocity of the new design reduces in several critical frequency ranges and the SPL on 7th point reduces by 1.2dBA.