Optimization Design And Performance Simulation Of Four-wheel Drive Car Transfer Case

With advances in automotive technology,people's requirements have not met for family cars in two-wheel drive models but begin courting can make full use of tire traction in four wheel drive mode.Now,more than four-wheel drive technology for off-road vehicles,many advanced cars also use this technique.Based on the transfer case of a timely four-wheel drive car,multiple-population genetic algorithm is used to optimize the transfer case structure and optimize the controller parameter.The specific contents completed are as follows:Firstly,this thesis describes the developing status of actuator and its researching status at home and abroad.And then the structure and working principle of the actuator are introduced.For understanding of the structure and working principle of the transfer case of four-wheel drive car,proposes transfer case multi-objective optimization design method based on the multiple population genetic algorithms in the four-wheel drive mode.In this thesis,a transfer optimization mathematical model was set up with maximum climbable gradient,fuel economy and the gear contact ratio,using MATLAB software for the optimization design.By the same time AVL Cruise software was used for the virtual simulation experiment of the vehicle.The results show that the optimized vehicle maximum climbable gradient lower 2.78 degrees,a 12.52% lower fuel consumption and planetary gear contact ratio increased by 8.62%;The experimental results are consistent with the optimization results and verify the correctness of the optimization results.Taking a four-wheel drive car in the intelligent control mode for research object,this thesis has established including engine model,the actuator model,gearbox model,transmission model,drive system model,tire model,whole car model,and auxiliary calculation module of whole car dynamics model.To facilitate modify the simulation model,the block type modeling is built by using MATLAB/SIMULINK software which provides a basis for vehicle dynamics simulation.By using the method of block modeling,the dynamic model and the transfer case of the four-wheel drive car control algorithm based on the PID controller,control target of four-wheel drive vehicle based on torque distribution,this thesis builds the off-line simulation platform under two different conditions: a driving wheel slip and accelerating running on a docking road surface.The use of multi-population genetic algorithm helpsdetermine the controlling parameters of PID controller.The simulation results show that: the transfer case controller of a four-wheel drive car according to the vehicle running status,distributed the torque to the front and rear axle on its own initiative which effectively inhibite the adhesion of wheel slip,so the tire can be fully used.