Study on influences of brake force distribution to vehicle motions (Numerical calculation of pitch motion and contact forces, and the comparison with experimental results)

Abstract

Appropriate relation among the inertia, suspension characteristics and brake force distribution will be required for achieving comfortable motion of vehicle and stable contact forces at braking. At a forethought stage where the design concept is decided, we usually do not know the detail specifications of inertia and suspension; therefore, simple analytical models would be desired to check the inertia and suspension characteristics for comfortable ride. In this paper, we propose a simple analytical model to express 2-dimenstional motions of a vehicle, at side view while braking. In the model, we can change the brake force distribution which include transitionally change, from the start of braking to the end. Then, we analyze by using the proposed model, how the brake force distribution influences the vehicle vertical and pitch motion, and contact forces at side view. The model is composed of the mass and the moment of inertia, of the suspension characteristics which are expressed two virtual links, springs and dumpers. In the model, the virtual links convert the horizontal brake forces into vertical reaction forces. The friction property fluctuations between brake pads and rotors may change the brake force distribution. This paper presents one method which makes it possible to design brake force distribution, having small influences to the vehicle motions and the contact forces, and to clarify the required characteristics for inertia and suspension at the forethought stage. The proposed model and the numerical calculation method with the model are confirmed by experiments.