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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.

Infinitely variable transmission (IVT) is one of the methods used to extend the ratio coverage. In this paper, a dynamic behavior analysis technology was developed for an IVT utilizing a half-toroidal variator as the shifting device. The traction coefficient of traction fluid used for the half-toroidal IVT varies greatly according to contact surface slip rate, contact pressure and fluid temperature. This paper used measurement values from a four-roller machine to identify the coefficient, and then applied it to the dynamic behavior analysis. Use of the identified traction coefficient enabled power transmission characteristic predictions of a half-toroidal variator. To reproduce the elastic deformation in actual operation, the research used the Finite Element Method (FEM) for modeling. This model was also used to visualize the frictional state of traction surfaces during operation.

A toroidal variator is the core part of an advanced Continuously Variable Transmission (CVT) design. Knowing its behavior and internal forces is key to defining the operational conditions of the transmission. To maintain a steady-state speed ratio, or to accurately and efficiently move between speed ratios, optimal trunnion control force is required. The unique design of the toroidal CVT makes the design very sensitive to trunnion positioning and force transients. Analytical understanding of the mechanism response is critical to toroidal variator controller design. A critical feature of the toroidal CVT simulation is representation of the friction forces in the disk-roller contact. This effect is important to the mechanism torque capacity and efficiency.

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.