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The metal pushing V-belt of a CVT equipped with a torque converter receives a sudden thrust load from the pulley when the CVT starts operation, and is required to begin transmitting torque from a stationary state with minimal time lag. In this study, the stress history of the area around the element neck under transient driving condition was clarified using new structural analysis technology to simultaneously simulate the dynamic behavior of the metal pushing V-belt and the element stresses. These results suggest that the compression stress generated by the load on the element V-surface is a fundamental component of element stress, and that bending stress generated by the compression force between the elements is superimposed on this stress. A comparison of simulation results with test results for the load distribution on the element, conducted to confirm the accuracy of the simulation, demonstrated good qualitative correlation.

In designing CVT pulleys, the effect of the fit clearance of the movable pulleys and their stiffness on the transmission efficiency and strength of the metal pushing V-belt is not necessarily clear. The research discussed in this paper introduced a pulley model that defined the pulleys as elastic bodies to a previously developed technology for the prediction of the transmission efficiency of the belts. As a result, it was found that when the fit clearance is reduced, the transmission efficiency of the belt is increased, and the amplitude of stress on the innermost rings and the element neck section is reduced. In addition, it was found that if pulley stiffness was reduced transmission efficiency was also reduced, and the amplitude of stress on the element neck section increased. This indicated that the fit clearance and the pulley stiffness changed the degree of deflection of the pulleys in the axial direction.

A simulation method enabling simultaneous prediction of dynamic behavior and stress distribution on an individual element has been developed for durability evaluation of dynamic strength of metal pushing V-belts. The finite-element-method that enables contact analyses in time history with large-scale model was adopted to reproduce the dynamic behavior of the V-belt in high rotational speed range of CVT. This paper focuses on the element strength in actual CVT operation, and also discusses modifications made to the previously reported simulation method to enable the prediction of detailed stress. A new technique named inertia-relief is introduced, which does not require the application of constraint conditions when calculating the detailed stress on element in respectively. This results in allowing the stress distribution on any element to be found at any position on the trajectory of the V-belt and the elastic deformation of the element to be identified.