Vacuum BoosterBrake Master Cylinder System Dynamic Model for Brake Pedal Feel

Abstract:

For the purpose of brake pedal feel analysis, the dynamic model of vacuum booster brake master cylinder system was established including the key structure components, gas and liquid. Many factors such as structure clearances, spring pre load, friction forces, reaction disc stiffness, the change of gas mass flow rate and brake fluid bulk modulus were taken into consideration in the model. Without vacuum assist, the experiments of vacuum booster and brake master cylinder were carried out respectively by using brake fluid or not, and the key parameters of the model were identified. Then, the simulation of vacuum booster brake master cylinder system performance was carried out. The simulation results in the stage of on brake were shown in 3 quadrants figure formed by the vacuum booster pushrod force stroke curve, the master cylinder stroke curve and the master cylinder pushrod force curve. A comparative analysis with experiment results verified the brake master cylinder dynamic model, vacuum booster mechanical system dynamic model, and vacuum booster brake master cylinder system model.