| The metal belt continuously variable transmission(CVT) is an ideal transmission form for automobile. Metal belt and pulley which are the key components of CVT, bear the function of transmitting torque and power. The CVT in current market is all straight generatrix pulley. The central line of the metal belt will deflect in the course of work because of the particular variable speed mode. Metal belt misalignment complicates the force between belt and pulley and destroys EHL between plate and pulley, meanwhile affecting the CVT transmission performance and efficiency. In this paper, the misalignment of the CVT metal belt was studied, and the following work were completed.(1)Based on the analysis of structure characteristics of the CVT metal belt and pulley, the mechanism of misalignment of the metal belt was expound. Basic geometric relationship of the CVT as well as calculation formula of the thrust between plate and pulley was derived. All of the above provide a theoretical basis for follow-up study.(2)A calculation model was built, which used the initial assembly size of pulley to define metal belt misalignment. Then, pulley deformation was introduced. The influences of wedge angle and pulley deformation as well as center distance on metal belt misalignment were studied.(3)Based on the analysis of plate force conditions of the metal belt misalignment, the stress was analyzed with the help of finite elements software and compared with normal condition. Power loss calculation formula of the metal belt misalignment was derived. Principle and inadequate of two control methods were analyzed. At the same time, taking minimum of mean absolute of axial misalignment as the object, a new method for alignment ratio optimization was presented by adjusting the initial assembly size of pulley.(4)The initial assembly size of pulley was tested. Firstly, the metal belt misalignment experiment system, which was divided into three modules, was finished. taking RD-CVT as the test object, a test was carried out under three typical working conditions. The results showed that the transmission efficiency of the system reached a maximum,when the initial assembly size of pulley was similar to the calculated size. The influence of metal belt misalignment on the transmission performance is least. Therefore, the optimal calculated initial assembly size of pulley is feasible. |
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