Structure Design And Anti-Slip Control System Of Magneto-Rheological Limited Slip Differential

With the development of industrial technology,the automobile industry is booming,and people’s living standards are getting higher and higher.Therefore,people put forward higher requirements for the safety and comfort of the vehicle.As an important part of the automobile transmission system,the limited slip differential(LSD)can effectively eliminate the disadvantage of "speed adjustment,no torque adjustment" of the gear differential,solve the problem of one side drive wheel slipping,and reduce the probability of accidents.Magnetorheological fluid(MR fluid)is a new kind of intelligent material.It can change its rheological properties and yield strength by adjusting the magnitude of external magnetic field in milliseconds,and the process is continuous and reversible.In this paper,the existing LSD has some problems,such as small locking coefficient,severe wear of parts and poor controllability.Based on the structure of gear differential,the LSD is designed by using this characteristic of MR fluid,and the anti-slip control system is established to study the slip resistance.The main contents of this paper include:(1)A new LSD structure is designed.The problems of gear differential and LSD are clarified.The structure and principle of them are analyzed.A new type of LSD composed of MR damper and symmetrical bevel gear differential is designed.Its structure and working principle are explained in detail.(2)Electromagnetic simulation and structure optimization of MR damper.Firstly,the magnetic circuit of MR damper is designed,and the static electromagnetic field simulation analysis is carried out in ANSYS software.Then,aiming at improving the magnetic flux intensity of the working face of MR fluid,the structure of MR damper is optimized based on the simulation results.The relationship between the magnetic flux intensity and the current is obtained through the simulation analysis of the optimized structure,Then the relationship between the magnetic induction strength and the current is obtained,and then the relationship between the limited slip moment and the current is determined.The mathematical model of MR damper is established by the relationship between the limited slip moment and the current.Finally,the modal analysis of the damping disk verifies the rationality of the structure.(3)The anti-slip control system is designed.Based on the driving principle of automobile,the reason of driving wheel slip is defined,and the common control methods are compared and analyzed.The fuzzy PID controller is proposed as the controller of anti-slip control system,and the slip rate of driving wheel is taken as the control objective of the controller.The structure and parameters of the controller are designed.The anti-slip system consists of four parts:speed control,anti-slip strategy,judgment module and whole vehicle model.(4)The model of anti-slip control system is established and simulated.Using Matlab/Simulink software and CarSim vehicle dynamics software,the anti-slip control system based on MR LSD is established.The joint simulation of anti-slip control is carried out for two typical working conditions of straight and curve double coefficient of adhesion road.By comparing the simulation results of fuzzy PID controller and PID controller,the superiority of fuzzy PID controller is verified.And by comparing the simulation results of installing gear differential and MR LSD,it is verified that the designed MR LSD can effectively solve the problem of one side drive wheel slipping.