针对某单缸柴油机在标定工况下正面产生异响问题，融合近场声压阵面法、同步压缩交叉小波变换法及模态分析法的优势，识别其异响特性。首先，在标定工况下采用近场声压阵面法定位了导致异响的铸铁后盖板总成辐射部件；然后，采用同步压缩-交叉小波变换法提取了后盖板总成异响与其激励响应的时频相关特征，结合频响函数法获得了铸铁后盖板总成结构共振是导致异响的关键结论；在此基础上，再基于有限元计算模态分析法比较了铸铁与铸铝后盖板总成的约束模态特性，找到了导致铸铁后盖板结构共振异响的薄弱环节；最后，采取托架板与加强筋设计措施提高了薄弱结构刚度，避开了共振频率区间。

For the abnormal noise from the front of a single cylinder diesel engine at the rated point，the abnormal noise characteristics were analyzed and identified by combining the advantages of near-field acoustic pressure front method, synchrosqueezed-cross wavelet transform method and modal analysis method. Firstly, the radiated parts of rear cast-iron cover plate assembly that produced abnormal noise were located by the near-field acoustic pressure front method at rated point. Then the synchrosqueezedcross wavelet transform method was proposed to extract the time-frequency correlated characteristics of abnormal noise and excitation response. The further application of frequency response function method led to the conclusion that the structural resonance of rear cast-iron cover plate assembly was the key factor of abnormal noise. Based on the finite element calculation modal method, the constrained modal characteristics of rear castiron and cast-aluminum cover plate assembly were analyzed and compared, and the weakness that led to abnormal resonance sound was found. Finally, the stiffness of weak structures improved by adopting the design of bracket plate and reinforcing rib, which avoided the resonance.