Research On Dynamic Wedging Characteristics Of High-speed Diagonal Strut Overrunning Clutch

The overrunning clutch is a key component of the aerospace drive system and is required to operate stably under severe conditions at high speeds and heavy loads,so its spragging performance has an important influence on the reliability of the drive system.In a test of a certain type of high-speed diagonal overrunning clutch,a spragging fault was found,which,if it occurs,will affect the normal use of the aircraft transmission system.In order to improve the durability and dynamics of the high-speed overrunning clutch and to reduce faults,this paper selects a high-speed overrunning clutch as the object of research,and carries out theoretical analysis,static contact simulation,wedge mechanism analysis and dynamic wedge characteristics research work.The specific research content is as follows.Based on the structural characteristics of the high-speed diagonal braced overrunning clutch,analyse its structural composition and working principle.The stress and deformation equations of the main components such as the sprags and the inner and outer rings in the sprag condition are summarised,the conditions for the self-locking of the clutch are derived and the force analysis of the sprags in the overrunning condition is carried out to obtain the solution equations for the forces between the sprags and the inner and outer rings.With the help of ANSYS Workbench software,a finite element model of a high-speed diagonal braced overrunning clutch is constructed and a static contact analysis of the clutch is carried out.Through the simulation analysis,the circumferential displacement between the sprags and the inner and outer ring,the slip distance between the contact surfaces and the distribution of the contact stresses are obtained,and the influence of the change in the load torque of the outer ring and the friction coefficient between the contact surfaces on the contact characteristics is investigated.The phenomenon of wedging failure in the wedging process of high speed skew stay overrunning clutch is summarized.The dynamic modeling of the clutch is carried out,and the construction method of the dynamic analysis model of the high speed inclined overrunning clutch is established.The mechanism of clutch wedging is analyzed and its dynamic working process is studied.The dynamic adjustment process of wedging is divided into five regions according to the working state.The changes of inner and outer ring speed,wedge swing Angle and contact force in each region are analyzed,and the factors leading to wedging failure are explored from the mechanism.The dynamic spragging performance of the high-speed overrunning clutch is simulated in ADAMS software by setting the parameters appropriately.The main indicators of clutch spragging performance are identified and the variation of the main indicators such as spragging impact,spragging time and maximum speed difference between the inner and outer ring during differential spragging are obtained.In comparison with the simulation results,the influence of parameters such as friction,spring torque,outer ring mass,damping and collision stiffness on the dynamic spragging performance of the clutch is investigated.