Search Results

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.

This paper presents four methodologies for modeling gear mesh excitations in simple and compound planetary gear sets. The gear mesh excitations use simplified representations of the gear mesh contact phenomenon so that they can be implemented in a numerically efficient manner. This allows the gear mesh excitations to be included in transmission system-level, multibody dynamic models for the assessment of operating noise and vibration levels. After presenting the four approaches, a description is made regarding how they have been implemented in software. Finally, example models are used to do a comparison between the methods

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.