Study On Working Performance And Structural Parameter Optimization Of Two-way Controllable Sprag Clutch

The sprag clutch is widely used in various transmission systems because of its large carrying capacity,sensitive response and simple structure.The conventional sprag overrunning clutch can only carry out unidirectional power transmission,but there is a demand for bidirectional torque transmission and braking in actual working conditions.Based on the configuration of conventional diagonal clutch,a new bidirectional controllable RL(Reverse-Locking)diagonal clutch is designed in this paper,which can realize bidirectional torque transmission and braking.On this basis,in order to meet the contact stress,slip angle and turn angle under specific working conditions,the working characteristics analysis and parameter optimization of RL sprag clutch are carried out.The main research contents and conclusions are as follows:(1)The working principle and performance requirements of the RL sprag clutch are analyzed,and the wedge constraint,lift constraint and strength constraint are set up.According to the actual working condition requirements,a variety of RL sprag clutch schemes are proposed.The contact stress,slip angle and swing angle are analyzed by finite element method,and the reasonable structural parameters of the RL sprag clutch are determined.(2)Based on the theory of elastic deformation and statics,a nonlinear iterative model for the wedge process of RL sprag clutch is established;based on the theory of kinematics and statics,the calculation formulas of clutch transmission angle and transmission friction torque are deduced.The transmission performance of clutch under different loads was analyzed by Adams.ABAQUS was used to analyze the stress changes of each component during clutch wedge under different friction coefficients.The results show that the braking performance and transmission performance of the designed RL sprag clutch meet the requirements,and the contact force and contact deformation of the outer ring are large.In the transmission process should avoid torque direction and transmission direction consistent,to prevent clutch vibration;the increase of friction coefficient of clutch contact surface can reduce the contact stress.(3)With the minimum clutch angle and outer ring contact force as the optimization objective,the clutch optimization function is established and its structural design constraint conditions are set.The design parameters are optimized by particle swarm optimization algorithm.The calculation results show that after the optimization of structural parameters,the braking angle of the theoretically calculated clutch is reduced by 47.5 %,and the normal contact force of the outer ring is reduced by 30.1 %.The finite element simulation model of the clutch before and after optimization was established and the results were compared.The simulation results show that the braking angle of the wedge is reduced by 34.9 %,and the peak stress of the wedge is reduced by 14.8 %.(4)The experimental platform of the RL sprag clutch is built,and the performance test experiment of the clutch is carried out.The transmission performance,braking performance and slip angle are tested and analyzed.The experimental results show that the transmission performance and braking performance of the designed RL sprag clutch are good,and the error between the slip angle test and the simulation results is not more than23 %,which provides experimental basis for the use of the RL sprag clutch.