Abstract: Aiming at the vibration problem of the fuel tank of agricultural single cylinder diesel engine caused by multi source excitation under the calibration condition, the structural dynamic characteristics of the fuel tank were identified by combining the Fourier Decomposition Method(FDM), the Synchronous Compression Wavelet Transform(SWT) method and the modal analysis technology. Firstly, the fuel tank vibration signal was adaptively decomposed and its timefrequency characteristics were extracted under calibration condition by the method of FDMSWT, the influence of mode aliasing effect on decomposition was eliminated and the timefrequency resolution was improved, the principal fourier intrinsic band functions components and their timefrequency characteristics of surface vibration signal of the fuel tank were obtained. Then, the modal analysis technique was used to identify the natural vibration characteristics of the tank under noload and half load conditions. On the basis of studying the correlation between the vibration response characteristics of fuel tank and its structural natural characteristics, the weak links that led to the deterioration of its dynamic characteristics were found. Finally, the structural design measures of adding indenting stiffeners were adopted at the bottom of the lower box to improve the structural rigidity of the fuel tank, the structural resonance frequency was avoided and the structural dynamic characteristics were optimized.

Key words:  , single cylinder diesel engine, fuel tank, modal analysis, dynamic characteristics, time-frequency characteristics

摘要： 针对某型农用单缸柴油机油箱在标定工况下受多源激励作用产生的振动问题，融合傅里叶分解方法(FDM)、同步压缩小波变换法(SWT)以及模态分析技术的优势识别油箱动态特性。采用FDMSWT方法进行标定工况下油箱半载状态振动响应信号的自适应分解与时频特征提取，消除模式混叠对分解结果的影响，提高时频分辨率，获取油箱表面振动信号的主傅里叶固有频带函数分量及其时频特性。采用模态分析技术识别油箱空载状态与油液作用下油箱半载状态的固有振动特性，在研究油箱振动响应特性与其结构固有特性两者相关性基础上，找到导致油箱结构动态特性变差的薄弱环节。通过下箱体底部采用增加压凹加强筋结构设计措施提高油箱结构刚度，避开结构共振频率，优化油箱的动态特性。

关键词: 单缸柴油机, 油箱, 模态分析, 动态特性, 时频特征