Stress Reduction in Push Belt Rings Using Residual Stresses An Approach Towards Increased Power Density for Push Belt CVT's

摘要

Since the push belt CVT first came into production, customer specifications on transmittable power, torque, space envelope, ratio coverage and durability have been extended. In answer to these changing demands, Van Doorne's Transmissie (VDT) dedicates itself to a continuous effort to improve the power density of its push belt. Power density can be increased by reduction of critical stress levels in the rings of the belt. Within the current belt interface this is realised by improved pre-bending. Rings are pre-bent in production. The process introduces a residual stress profile in the ring that helps to lower stress levels in critical areas during operation in the variator. Ring load analysis indicates that further improvement of the pre-bend process is possible. This paper describes a theoretical model that helps to understand the stress critical areas in the rings that can be influenced by the pre-bend process. Theory is checked with experimental results revealing that model and test are consistent. Improvements have been implemented in the new push belt design to increase the power density of CVT applications.