| Since the metal belt type CVT was invented in 1970,it has a continuous gear ratio,which brings good fuel economy and handling stability to the car.Under the same working conditions,a car equipped with a metal belt continuously variable transmission saves 7% to 15% of fuel than a car equipped with an automatic transmission.However,the metal belt type CVT requires a supporting hydraulic mechanism for speed regulation,and this hydraulic mechanism becomes the main energy consumption unit of the transmission.Especially in the operation process,the metal belt and the pulley are easy to wear,which affects the service life of the entire transmission.This article will design a new type of CVT stepless transmission to make its structure simpler and more reliable,and greatly reduce the wear between the belt and the pulley.Compared with the traditional CVT transmission,the transmission efficiency is higher and the service life is longer.Therefore,it can be better promoted and used in small-displacement fuel vehicles or electric vehicles to achieve the purpose of reducing fuel consumption and protecting the natural environment.Through theoretical analysis,the feasibility and theoretical transmission performance of the designed electric-driven sliding-rail variable-diameter continuously variable transmission structure are verified.Computer simulation software is used to simulate the transmission and the electronic control system is tested.The main research contents and conclusions of thesis paper are as follows:1.By comparing the current existing vehicle transmissions,analyzing and summarizing the advantages over CVT,comparing the advantages and disadvantages of the existing metal belt CVT,designing a new structure of electric drive slide type variable diameter CVT,through Solid Works2018 Make a three-dimensional model of each component and finally assemble it into a complete transmission model.2.Use Solid Works2018 to check the interference of the three-dimensional model of the electric drive slide-type variable diameter continuously variable transmission,use the motion simulation module motion to verify the feasibility of the transmission,and perform the motion simulation of the transmission.3.Through the mechanical analysis method of the metal belt type CVT,the mechanical analysis of the transmission is carried out,the superposition formula of the tension of the pulley is established,and the maximum torque that can be carried is calculated.The relationship between the radius of the driven pulley,the tension of the pulley and the initial torque that the driven pulley can output is made through MATLAB.4.According to the relationship between the displacement of the slider and the radius of the pulley,the speed ratio equation is obtained,and according to the speed relationship between the ball screw nut seat and the stepper motor,the relationship equation between the speed of the stepper motor and the speed ratio is finally calculated.5.Analyze the relationship between the tension of the pulley and the extrusion force of the pulley slider,use the Solid Works2018 motion simulation module motion(including the ADAMS solver)to perform dynamic analysis on the transmission,and calculate the thrust required by the ball screw nut seat.The stepper motor and ball screw are selected,and finally the shift mechanism is designed,and the relevant data is obtained by doing experiments. |
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