Approach fort he development of suspensions with Integrated Electric Motors

Abstract

Conceptual design is an innovative and strategic phase in the process of product development. In this phase the concept generation and decision-making have a critical impact on the following long-term product development. However, it is challenging to generate realizable novel concepts and then make the right decision because of involved extensive interdisciplinary areas and insufficient design information. Lightweight design is a non-negligible and high priority subject in the concept design phase of electric vehicles. Combining the drive unit into suspension links is an effective engineering solution to achieve system lightweight while realizing the increase of the unsprung mass in small proportion. However, several questions arise from this idea: how to systematically generate and evaluate the concept suspensions with consideration of function complexity, physical parameter multiplicity and their intricate relationships? How to design a new axle structure to suit the new concept after the combination and meanwhile further reduce the suspension mass? How is the ride dynamics of the vehicle with the new suspension? This thesis presents a design methodology for the development of concept suspensions whose links are combined with electric motors. Firstly, a new conceptual design approach to integrating the functions of two objects based on the Axiomatic Design method is proposed. In this approach, the functional integration process is formulaically and explicitly expressed by matrix equations. In this way, the system functions, corresponding parameters and their relationships can be investigated in the design matrices. Then this approach is applied to the design of concept suspensions which integrate the functions of electric motors. The generated concepts are evaluated and selected by comparing their design matrices according to the Axioms introduced in the theory of Axiomatic Design. Following this, a reference suspension is tested and the suspension parameters are used as the benchmark for the concept suspension development.