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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.

A pushing metal V-belt is the core part of a Continuously Variable Transmission (CVT). Knowing its behavior and internal forces is key to defining the operational conditions of the transmission. To maintain the steady-state speed ratio, an optimal pulley thrust is required. If the force is too large, the transmission efficiency is affected; if too small, the belt slips. Because so far the optimal value of the pulley thrusts had been derived from physical test, analytical understanding of this effect was lacking. In the physical test, controlled thrust is applied to one of the pulleys, further complicating the simulation process. This article describes a new simulation technique developed to resolve this problem. To predict the motion of the belt, a simulation was created, using a multi-body analysis code with a feedback control applied to the pulley thrust. The analysis model consisted of numerous elements, a multi-layer ring, and a pulley set.