Abstract: In order to solve the failure problem of the sun gear of wheel-side reducer in the drive axle assembly gear fatigue bench test, the comprehensive analysis of macro profile, chemical composition, metallographic structure, hardness and hardened depth of the failure sun gear is carried out. This paper supposes the failure cause of the sun gear is the unbalance load. The finite element analysis of the drive axle assembly based on MASTA shows that the safety factor of gear contact fatigue is less than 1 and the contact between the sun gear and the planet gear is unbalanced. Therefore, it is inferred the failure cause of the sun gear is the unbalance load of gear causes excessive local stress on tooth surface. In order to improve the failure cause of the sun gear, the tooth width of the sun gear is increased by 10 mm and the gear shape is modified. The failure problem is solved. This study provides a basis for the failure analysis and improvement of sun gear.

Key words: wheel-side reducer; sun gear; failure analysis

摘要： 为了解决驱动桥总成齿轮弯曲疲劳台架试验中轮边减速器太阳轮失效问题，文章对失 效太阳轮的宏观形貌、化学成分、金相组织、硬度及硬化层深度等方面进行综合分析，推测 太阳轮失效原因为齿轮受力偏载。基于 MASTA 软件对驱动桥总成进行有限元分析，发现太 阳轮的齿轮接触疲劳安全系数小于 1 而且与行星轮之间存在明显的边缘接触。因此，推断出 太阳轮失效的原因为齿轮受力偏载导致齿面局部应力过大。针对太阳轮失效原因进行改进， 将太阳轮的齿宽增加 10 mm 并进行齿轮修形，失效问题解决。该研究为太阳轮失效原因分析 及改进提供了依据。

关键词: 轮边减速器；太阳轮；失效分析