Property Analysis And Reserch On The Key Technology Of The Four-wheel Drive Vehicle And Electronically Controlled Limited Slip Differential

With the development of automotive technology,four-wheel drive vehicles are increasingly getting popular among customers,and many car manufacturers have also introduced various kinds of four-wheel drive(4WD)vehicles.However,the research on electronically controlled limited slip differential that is the key component of the four-wheel drive vehicle power distribution is rare,and no mature theoretical system is formed.Therefore,it is of great theory significance and application value to carry out the theoretical research on electronically controlled limited slip differential of four-wheel drive vehicles.Based on the analysis and summary on the key components of the inter-wheel power distribution of four-wheel drive vehicles at home and abroad,this paper analyzed the structural characteristics of the three types of limited slip differentials in the four-wheel drive vehicle transmission system,and focused on the construction of the electronically controlled limited slip dynamic analysis model and a detailed analysis of the electronically controlled limited slip differential torque distribution and transmission characteristics.A research method combined with theoretical analysis,numerical simulation and experiments was adopted for an in-depth study on intelligent electronically controlled limited slip differential.The main research procedures and results are summarized as follows:(1)The paper expounded the structural characteristics of the mechanical limited slip differential,the viscous coupling and the electronically controlled limited slip differential,and then analyzed their characteristics sepatately,and deduced the formulas of dynamic transmission characteristic of the three kinds of differentials.Based on this,the dynamic analysis model of the electronically controlled limited slip differential was established.Then this paper analyzed the torque distribution characteristics and the transmission characteristics of the electronically controlled limited slip differential,and carried out the transmission efficiency simulation and analysis on the electronically controlled limited slip differential.(2)Aiming at the structural characteristics of the electronically controlled limited slip differential,a digital design of the electronically controlled limited slip differential was carried out.The electronically controlled limited slip differential part reconfigurable design based on the adaptive design made a exposition of the differential components adaptive design and key technologies of automatic assembly,and then,the reconfigurable design of the electronically controlled limited slip differential software was developed on the basis of Visual C #.net and Sql Server software.(3)This paper analyzed the mechanical characteristics of the electronically controlled limited slip differential and established the analytical formula under the ultimate work condition of the differential,and carried out the modal test,finite element modal analysis,static analysis and fatigue life analysis of the electronically controlled limited slip,which provides a reference of the differential layout on the chassis.(4)The fluid-solid coupling characteristics of the electronically controlled limited slip differential based on the meshless theory was studied.By establishing the two-phase flow model,the flow characteristics of the flow field in the closed volume were analyzed,which provides a theoretical method for the mechanical parts lubrication design of differentials.(5)In order to study the transmission characteristics of the multi-plate clutch in the electronically controlled limited slip differential,the accuracy of the multi-plate clutch dynamic model was verified based on the combination of simulation and test.On this basis,the paper analyzed that how the multi-disc clutch key dimension affected the transmission performance of the mechanism.Finally,based on genetic algorithm,a multi-objective optimization design of the multi-chip clutch structural parameters was made,which offers referential meaning to the multi-plate clutch design.(6)In order to study the steering stability of vehicles under special pavement and working conditions,the influence of driving force distribution and braking force distribution on improving vehicle handling stability was discussed.Based on the theory of hierarchical coordination control,this paper designed the upper controller of the automotive electronic stability control program and dynamic driving force distribution control system,and ESP was controlled by fuzzy control and the driving force distribution control system was controlled by PID control based on neural network design.On this basis,this paper carried out the simulation of control system performance under a variety of typical operating conditions,then the hardware-in-loop test simulation platform was built by using NI-PXI equipment,and the control system was verified by experiments,which provides the theory for the next development of the control system in-kind.