三缸机相对于其他多缸机平衡问题更加复杂，可采用平衡轴设计来抵消发动机工作中的不平衡力矩，而增加平衡轴后发动机结构强度面临挑战。以某三缸发动机升级机型的结构强度为研究对象，搭建动力学模型获取发动机缸体所受的工作载荷，搭建有限元模型对平衡轴及缸体进行应力分析，使用疲劳软件对缸体进行疲劳强度校核。最后通过应变测试对仿真结果中的危险位置进行验证，保障发动机结构强度设计可靠性。

Compared with other multi-cylinder engine, 3-cylinder engine has a more complex balancing problem. The balancing shaft design was generally used to offset the unbalanced torque during the operation of engine, but the engine structureal strength design would be challenged after the balancing shaft was used. Taking the structural strength of a 3-cylinder engine upgraded model as the research object, the dynamic model was built to acquire the working load of engine block, the finite element model was constructed to conduct the stress analysis of balancing shaft and cylinder block, and the fatigue strength was further verified with the fatigue software. Finally, the weak position determined by the simulation was verified by the strain test and the reliability of engine structureal strength design was guaranteed.