Research On The Adjustable Centrifugal Clutch For Two-Speed Transmission Of Electric Vehicle

The key technologies of adjustable centrifugal clutch used in the two-speed power transmission of pure electric vehicles are studied in this paper.For the requirements of two-speed power transmission of pure electric vehicles,connection scheme of adjustable centrifugal clutch and planetary gear is given.The model of two-speed power transmission is established,and the feasibility of the scheme is verified comparing to the national standard.Considering the friction work and the impact degree in the gear shift,the optimization method of clutch torque is given in order to reduce the torque demand of clutch,and the optimization results are listed.The structure of the clutch body and the adjusting mechanism are designed.The arm adjusting principle is used in the clutch,and the clutch engagement speed and torque of clutch engagement can be adjusted.For the relative angle control requirements of two rotating parts,the control structure of relative angle between the regulating arm and centrifugal shoe is given after comparing two schemes.Analyzing four main factors of adjustable centrifugal clutch torque,the analytical model of adjustable centrifugal clutch is obtained.Taking the clutch torque as the constraint condition and the minimum clutch mass as the target,the genetic algorithm is used to optimize the clutch structural parameters.The solid model is established according to the clutch structural parameters,and the clutch torque regulation characteristics for the adjusting arm angle from 0~0 to 90~0are analyzed.The results show that the clutch torque characteristics can meet the requirements of the two-speed transmission of pure electric vehicles when the clutch rotates along the direction of increasing force.The virtual prototype of clutch is set up using multi-body dynamics tool,and the analysis result of clutch model is verified.The results show that the clutch model can reflect the basic characteristics of the clutch.The clutch virtual prototype is embedded into the whole model of the two-speed transmission,and the clutch adjusting arm control model is given.The analysis of the gear shift shows that the clutch dynamics can meet the requirements of the two-speed transmission.The finite element model of the clutch is established,and the pressure distribution of the friction pairs under the distributed centrifugal force is analyzed.It shows that the contact pressure near the pin of the friction is slightly larger than the contact pressure at the far from the pin.The thermal mechanical coupling of clutch during positive torque gear shift is analyzed,and the temperature distribution of clutch is given.The analysis of the clutch stress distribution in the gear shift shows that the adjusting arm and the centrifugal shoe turn pin hole are the larger stress distribution regions of the clutch.The experimental research of clutch prototype is carried out.The clutch prototype is processed,and the XPC test system is built.The real-time synchronous control and data acquisition of the clutch control motor,the drive motor and the load motor are realized.The clutch engagement speed,the maximum torque at the engagement speed and the clutch torque adjustment are tested.The experimental data show that the adjustable centrifugal clutch can adjust the engagement speed and the torque after the engagement.The experimental data show that the experimental data are in good agreement with the theoretical analysis,which shows that the clutch model reflects the basic characteristics of the clutch.