| The output characteristics of the motor in electric vehicles are very favorable to the driver of the vehicle,but in order to make the electric vehicle take into account the low speed climbing and high speed driving and have a high energy conversion rate,it is very important to equip the electric vehicle with transmission.The power and economy of electric vehicles will become better due to the application of CVT which has the characteristics of continuous change in speed ratio,however,the new challenge of metal belt transmission will be brought by the increase of rotational speed.Therefore,in order to improve the transmission reliability of CVT under the condition of high rotational speed,the mechanical characteristics of metal belt CVT under high rotational speed condition is analyzed,the improvement measures are proposed due to the change of the mechanical characteristics of the metal belt at high rotational speed,and mainly carries out the following research work:(1)The basic composition and transmission mechanism of metal belt CVT is discussed,the geometrical relation of CVT transmission is deduced,the force of metal sheet and belt ring under stable condition is analyzed,and the load distribution model of metal sheet and belt ring is deduced based on the idea of iterative method.The influence of high rotational speed condition on the stress state of metal belt under different speed ratio is obtained by numerical solution of load distribution model,which provides the basis for the follow-up research.(2)Three-dimensional solid model of CVT is established by SolidWorks software through the bottom-up assembly method,and the finite element simulation model of CVT is obtained by using the finite element software ANSYS Workbench.The stress distribution of metal sheet,belt ring and belt wheel under different torque,rotational speed and the speed ratio is simulated by simulation.The deformation of belt wheel under different speed ratio is analyzed,the analysis results are compared with the existing test data,and the validity of the finite element model and simulation results is verified to some extent.(3)Through the simulation analysis of CVT finite element model,it is found that when CVT is driven under the condition of low speed ratio and high rotational speed,metal belt transmission reliability is reduced due to the large centrifugal force on the traditional bearing steel metal sheet which leads to the band ring stress greatly increased.The improvement of the force state of the belt ring is taken as the goal,and after a variety of improvement schemes are compared,the lightweight improvement of the metal sheet using magnesium alloy material is proposed,and the improved force state and stress state of the metal belt are analyzed and obtained.(4)The wear type of metal sheet is analyzed,and the calculation method of the side wear depth of the metal sheet is deduced on the basis of the Archard wear model,the life estimation model of metal sheet based on CVT finite element analysis results is established,and the service life of metal sheet is converted into the total mileage of electric vehicle fitted with CVT,and the total mileage of electric vehicle before and after improvement under high speed condition is compared and analyzed. |
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