Analysis On Dynamic Contact And Wear Characteristics Of Centrifugal Disengagement Overrunning Clutch

The centrifugal disengagement overrunning clutch is mostly used in the auxiliary power unit(APU)of various aircraft.It is located between the starting DC motor and the gear train of APU gearbox to ensure the timely engagement and disengagement between the starting DC motor and the gear train of APU gearbox.It has the characteristics of high working speed and compact structure.This paper takes the centrifugal disengagement overrunning clutch as the research object,and studies the influence of working condition parameters and geometric parameters on the dynamic contact performance,wear characteristics and dynamic performance of this type of clutch.The main contents of this paper are as follows:Based on the classical Hertz contact theory model and the basic parameters of standard wedge,the parameters of centrifugal disengagement overrunning clutch are designed.This paper studies the classical iterative method of wedge contact angle calculation,constructs the analytical mechanical model of overrunning clutch in APU startup state,working state and windmill state,designs and checks the clutch and solves the critical speed of centrifugal disengagement of wedge.The finite element analysis model of centrifugal disengagement overrunning clutch is established.The contact characteristics and stress distribution between the clutch wedge and the inner and outer sleeve raceways during APU start-up are studied and compared with the theoretical analytical value.This paper discusses the influence of the deviation between the axis of wedge and raceway caused by machining error and installation error on the contact characteristics and stress distribution of overrunning clutch.The ADAMS virtual prototype model of centrifugal disengagement overrunning clutch is established.Explores the dynamic performance of the clutch under different working conditions,explores the specific parameter values under different working conditions,and compares them with the theoretical analytical values.The influence of wedge wear on the dynamic performance of the clutch is discussed,and the influence of wedge wear on the parameters such as the contact force of the inner raceway of the clutch,the torque of the input shaft and the critical disengagement speed of the wedge are obtained.The wear failure mechanism of clutch is studied.Based on Archard adhesive wear model,the adhesive wear life of clutch under windmill condition is analyzed.Dynamic analysis of the wear phenomenon between the clutch wedge and the aircraft starting track is proposed.The adhesive wear and impact wear life were obtained.Conduct clutch dynamic performance test.The small friction torque value of clutch at 100 RPM windmill speed is 66.47 N.mm,which has a certain error compared with the theoretical analysis value of 73.74 N.mm.However,with the increase of windmill speed,the test value and the theoretical analysis value show the same decreasing trend,verifying the correctness of the theoretical analysis method.The research work of this subject provides an idea reference for the dynamic contact performance analysis method of centrifugal disengagement overrunning clutch.Also provides technical support for the design of similar overrunning clutch,and a theoretical basis for the research on the wear characteristics of centrifugal disengagement overrunning clutch.