Wheel Envelope Methodology

Abstract

A Wheel envelope is an important aspect of chassis engineering and is developed early in the development process. A Wheel envelope represents the maximum swept volume of a wheel according to the agreed standards and methods. The aim of this master thesis was to realize the concept of a wheel envelope and develop an analytical method for the wheel envelope development. Knowledge of parameters which will influence the wheel envelope development is required. Knowledge of geometrical tolerances of certain components from the suspension system and the wheel are needed as they contribute to the tolerance stack up. The compliance in the suspension bushings is also studied to understand it’s effect on the displacement of wheel center position. A steering strategy is explained based on the driving condition of the vehicle and, details about the tyre sections which include summer tyre, winter tyre and use of snow chains. For the method, parameters which will influence the envelope design was listed. Geometrical tolerances from components such as control arm, spring, damper were studied and a method to calculate the stack up of tolerances in the tolerance chain was established. Compliance from the bushings have significant influence on the displacement of wheel center position. A method was established to estimate the deflection in the wheel center position due to compliance of the bushings and forces acting on the wheel in the longitudinal and lateral directions. Steering strategy is influenced by the type of vehicle for which the envelope is being developed and the driving conditions. Hence, a generic method to create steering strategy by considering the bump travel, rebound travel and steering rack travel was established. Snow Chains are mandatory on certain markets. Therefore, steering strategy for a wheel with a snow chain was created.