Abstract:  Gear geometry and meshing properties of the low-angle face gear drives were investigated in order to enhance meshing capabilities of the gear drives with small shaft angle in helicopter transmission systems. The applied coordinate systems for generation of the low-angle face gear drive were established and the equation of the tooth surface of the small cone angel face gear was derived based on gear meshing theory. The tooth surface equation of a double-crowned cylindrical involute pinion was deduced by application of a generating worm.  The generated double-crowned pinion was then introduced into the low-angle face gear drive. The TCA was implemented and the influences of misalignments on the contact were researched. Stress analysis was performed for the purpose of evaluating the performance of the proposed face gear drives. And the stresses of the low-angle face gear drive were compared with the conical involute gear and cylindrical involute gear pair. The results show that the application of double-crowned pinion avoids edge contact， providing lower contact and bending stresses compared with the face-gear drive with a longitudinal modification pinion. Under the same conditions， the contact and bending stresses of the tapered face gear are 27% decrease than that of the conical involute gears. 

Key words: low-angle face gear drive, tooth surface generation, tooth contact analysis（TCA）, stress analysis

摘要： 为了增强直升机传动系统中小角度齿轮传动副的啮合性能，对小轴交角面齿轮副进行齿面几何与啮合特性研究。建立了小轴交角面齿轮副展成坐标系，并基于齿轮啮合原理推导了其齿面方程。基于蜗杆推导了拓扑修形的圆柱齿轮齿面方程，并将该圆柱齿轮应用到小轴交角面齿轮副中。进行了轮齿接触分析，并研究了安装误差对啮合的影响规律。为评价小轴交角面齿轮副的传动性能，进行了应力计算分析，并与锥形渐开线-圆柱齿轮副进行了对比。研究结果表明：相对于圆柱齿轮齿向修形，拓扑修形可有效避免小轴交角面齿轮副的边缘接触，减小接触应力和弯曲应力；相同参数下，小轴交角面齿轮副的接触应力和弯曲应力均比锥形渐开线齿轮-圆柱齿轮副小约27%。

关键词: 小轴交角面齿轮副, 齿面展成, 轮齿接触分析, 应力分析