柴油机缸盖罩动态特性分析与改进

Dynamic Characteristics Analysis and Modification of the Engine Cylinder Cover

以某四缸柴油机铸铝缸盖罩为研究对象,融合频谱分析法、近场声压法及模态分析法的识别优势,分析缸盖罩的动态特性。首先在标定工况下采用时频谱结合频响函数分析了缸盖罩的振动响应特性,然后基于近场声压法定位分析了缸盖罩结构噪声的辐射特性,在建立缸盖罩有限元仿真模型基础上,再结合试验模态法与计算模态法获取了缸盖罩在柴油机约束状态下的模态特性,找到了导致结构动态特性变差的薄弱环节,最后采取薄弱结构加强筋设计与隔声措施优化了缸盖罩的动态特性,并进行了降噪试验验证。

Taking the cast aluminum engine cylinder cover of a four-cylinder diesel engine as the research object,the dynamic characteristics of the engine cylinder cover were analyzed by combining the identification advantages of spectrum analysis method,near-field acoustic pressure method and modal analysis method.Firstly,the vibration response characteristics of the engine cylinder cover were analyzed by using the time-frequency spectrum and frequency response function under a rating condition.Secondly,the radiation characteristics of structure noise for the engine cylinder cover were analyzed by the near-field acoustic pressure method.On the basis of the finite element simulation model of engine cylinder cover,the modal characteristics of the engine cylinder cover under the constraint condition of the diesel engine were obtained by combining the testing and computational modals,and the weak link leading to the deterioration of the dynamic characteristics of the structure was found.Finally,the dynamic characteristics of the engine cylinder cover were optimized by adopting the design of weak structural reinforcement and sound insulation measures,and the noise reduction test was verified.