Thermal Structural Analysis And Optimization Design Of CVT Box

Automobile transmission is one of the core components of automobile transmission system,among which,Continuously Variable Transmission(CVT)is widely concerned for its continuous changing of speed ratio which can improve fuel economy.The metal belt CVT box is the key component of the bearing transmission shaft,and its mechanical properties under the coupling action of ther mal structure directly affect the reliability and performance of the transmission.Therefore,this paper takes the metal belt CVT box as the research object,aiming at the strength and stiffness requirements of a domestic metal belt CVT box at higher tempe rature,combined with theoretical calculation and thermal structure coupling analysis method,the following research work is completed specifically:(1)Transmission dynamics analysis.The torque and transmission ratio of each shaft of CVT are calculated.Axial thrust of metal steel belt and belt wheel is calculated.The balance equation of the transmission shaft is established to calculate the force at the hole of each bearing seat.The motion and force of CVT under different transmission ratios were studied.(2)Heat balance analysis of the box.Calculate the heat production and heat loss of each part of CVT transmission.The thermal balance model of the transmission was established by lumped parameter method,and the equilibrium oil temperature and wall temperature of the transmission were obtained at various ambient temperatures.(3)Finite element thermal structure coupling analysis.Constraint conditions were added to the finite element software according to the thermal boundary conditions obtained from the heat balance analysis,and thermal steady state analysis was carried out on the finite element model to obtain the temperature distribution cloud map of each part of the box.Then the thermal load and mechanical constraints were applied to the thermal structure coupling model to obtain the thermal deformation of the box.The parallelism between adjacent shafts of the box body is calculated under the thermal steady state,static analysis and thermal structure analysis,and the influence of the deformation of the box body on the parallelism between each transmission shaft is analyzed,and the weak parts of the box body are obtained.(4)Optimal design of the box.A reasonable optimization scheme for improving the stiffness and strength of the box is put forward.The parts that need to be optimized in the finite element analysis are optimized.It mainly includes the improvement of shell wall surface,the optimization design of suspension and the optimization of shell parameters.This paper takes the metal belt CVT box as the research object,carries on the dynamic analysis,the thermal characteristic analysis,the thermal structure coupling analysis and the optimization design and so on,provides a reasonable analysis idea and the solution for improving the rigidity and strength of the metal belt CVT box under the thermal state characteristic.It has certain engineering value in the design,analysis and optimization of CVT transmission.