Studies on Brake Pedal Feeling Based on a Novel Mechatronic Booster 2016-01-0014

Nowadays, the vehicle market puts forward urgent requirement for new kinds of braking booster because the traditional vacuum booster cannot meet the demands of new energy vehicles anymore. However, one problem that all the new plans should face is how to guarantee an ideal pedal feeling. In this paper, a novel mechatronics braking booster is proposed, and servo motor introduced into the booster makes the assist rate can be adjusted under a great degrees of freedom, so the structural parameters and control parameters of the booster should be determined elaborately to get an optimal pedal feeling. The pedal feeling is always represented by the pedal stoke-force curve which is influenced by different parameters. In this paper, the pedal stoke-force curve is firstly studied by batch simulation using AMESim, different structural and control parameters, such as the parameters of the decelerating devices, the stiffness coefficient of the return spring, the assist rate of the booster, are investigated. Results show that structural parameters influence the pedal feeling in a rigid way, such as, the lead angle of the screwing gearing can cause self-locking if not chose well, resulting in bad pedal feeling and cause security problems; yet control parameters can influence the pedal feeling flexibly, so we can adjust the assist rate to get a good pedal feeling under different conditions. Finally, the bench test is carried out under different operating conditions whose results show that the booster has an ideal pedal force-stroke curve just similar with traditional vehicle. The method that verified in this paper can be used to eliminate the time-consuming calibration work, providing a theoretical basis for the design of new braking boosters.