某拖拉机风扇系统共振分析及改进

周伟伟^1，2，赵婧婧^1，2，郭彬^1，2*，范增^1，2

1.内燃机与动力系统全国重点实验室，山东 潍坊  261061；2.潍柴动力股份有限公司，山东 潍坊  261061

摘要：为解决某拖拉机开发过程中出现的风扇扇叶根部断裂故障，针对某6缸柴油机常用转速区间工况，采用模态分析与频谱分析相结合的方法分析故障原因，据此提出改进方案并进行仿真和耐久试验验证。结果表明：风扇1阶模态频率与发动机3阶激励频率在常用转速区形成共振，导致扇叶根部双向弯曲疲劳失效；采取保持风扇直径不变，扇毂厚度增加2 mm的改进措施后，风扇1阶模态频率由108 Hz提高到150 Hz；改进后的风扇经500 h耐久试验未断裂，改进措施有效。旋转机械系统设计应重点控制关键部件模态频率与激励频率的耦合关系，通过优化结构参数调整模态分布，可在保证性能的前提下规避共振风险。

关键词：风扇；模态分析；频谱分析；共振特性

Analysis of resonance in a tractor fan system and its improvement

ZHOU Weiwei¹,2, ZHAO Jingjing^1,2, GUO Bin^1,2*, FAN Zeng^1,2

1. State Key Laboratory of Engine and Powertrain System, Weifang 261061, China;

2. Weichai Power Co., Ltd., Weifang 261061, China

Abstract: To address the issue of fan blade root fracture during the development of a certain tractor, the combined approach of modal analysis and spectral analysis are employed to identify the root cause under the common operating speed range of a 6-cylinder diesel engine. Based on the findings, an improvement solution is proposed and validated through simulation and endurance testing. The results indicate that the first-order modal frequency of the fan resonated with the third-order excitation frequency of the engine within the common speed range, leading to bidirectional bending fatigue failure at the blade root. By maintaining the fan diameter unchanged and increasing the hub thickness by 2 mm, the first-order modal frequency of the fan is raised from 108 Hz to 150 Hz. The improved fan doesn′t break after a 500 h durability test, which indicates that the improvement measures are effective. In the design of rotating machinery systems, it is crucial to control the coupling relationship between the modal frequencies of key components and excitation frequencies. Optimizing structural parameters to adjust modal distribution can mitigate resonance risks while ensuring performance.

Keywords: fan; modal analysis; spectral analysis; resonance characteristic