斜撑式超越离合器接触分析

Contact Analysis of Sprag-type Overrunning Clutches

斜撑式超越离合器在航空发动机和直升机传动系统上广泛应用,针对其接触特性进行研究,对设计高可靠性的斜撑式超越离合器有重要的意义。基于Hertz接触理论,研究了转矩、摩擦因数对斜撑式超越离合器接触特性的影响,通过有限元法研究了斜撑式超越离合器的动态接触特性。结果表明,考虑摩擦力的情况下,斜撑块与内外环接触时会同时发生滚动和滑移;斜撑块与内外环的接触应力呈偏心率较大的椭圆状分布;斜撑块与内外环的接触应力沿斜撑块长度呈开口向下的抛物线形状分布;最大接触应力不能反映转矩对接触应力的影响;超越离合器传递的转矩与其扭转角正相关;摩擦因数不影响最大接触应力和超越离合器的扭转角;摩擦因数与接触滑移量呈非线性关系,与最大摩擦应力呈线性关系。

Sprag-type overrunning clutches are widely used in aeroengines and the helicopter transmis⁃sion system.The research on the contact properties of sprag-type overrunning clutches has important signifi⁃cance to the design of high reliability clutch.In order to study the effects of torque and coefficient of friction on the contact properties of sprag-type overrunning clutches,Hertz contact theory and finite element method are used to investigate the dynamic contact properties of sprag-type overrunning clutches.The results show that both rolling and sliding occur when friction is considered,the contact stress between sprags and races is ellipti⁃cally distributed with a large eccentricity,the contact stress is distributed in the parabolic shape along the length of the sprags,maximum contact stress couldn't reflect the effects of torque on contact stress,the torque transmit⁃ted beyond the clutch is positively correlated with its torsion angle,the coefficient of friction doesn't affect the maximum contact stress and the torsion angle of the clutch,the coefficient of friction is nonlinear with the sliding distance and linear with the maximum friction stress.