Abstract:

In this paper,the transmission principle of the continuously variable transmission with traction drive is analyzed,and the factors affecting the traction coefficient of the contact path and the corresponding solving methods are explored. Then,based on the relationship of the traction coefficient between the inner and the outer friction pairs,the normal force loading on the inner and the outer friction pairs,as well as the slip-roll ratio of the outer friction pairs,is investigated,and the main causes and solving method of the power loss are analyzed. Finally,the variations of the normal force,the power loss of spinning,the power loss of slipping and the transmission efficiency with the transmission ratio are discussed. The results show that ( 1) under given input rotational speed,torque and slip-roll ratio of the inner friction pairs,the normal force slightly increases with the transmission ratio; ( 2) with the increase of transmission ratio,the power loss of slipping increases while the power loss of spinning decreases,the effect of the power loss of slipping on the system transmission power becomes more important while the power loss of spinning has an opposite effect; ( 3) the total power loss decreases with the increase of transmission ratio and tends to be constant in the end; and ( 4) the total transmission efficiency of the system increases with the transmission ratio and tends to be constant,with its value remaining constant at about 83% in the end.

Key words: continuously variable transmission, traction drive, traction coefficient, transmission efficiency, sliding, spinning