Brake pedal feel characteristic is determined by the structural and kinetic parameters of the components of the brake system. As the servo power component of the brake system, vacuum booster has a significant influence on the brake pedal feel. In this paper, a brake system model for brake pedal feel which has a detail vacuum booster mathematical description is established in the software MATLAB/Simulink. The structure gaps, spring preload, friction force and reaction disc characteristics of vacuum booster are considered in this model. A brake pedal feel bench test under different input velocity and vacuum pressure is completed in order to validate the prediction of the model. Finally, based on the assessment index in pedal travel, pedal force and master cylinder pressure three-quadrant diagram, the influence of vacuum booster design parameters such as structure gaps, spring preloads, press plate and press ring areas, diaphragm effective area and reaction disc stiffness on the brake pedal feel characteristics is analyzed and discussed. This study can serve as important reference for vacuum booster design and adjustment.
