Quasi-Static Mechanical and Dynamic Flow Model of Brake Vacuum Booster Using Hybrid Methodology

This study primarily focuses on quasi-static mechanical modeling and dynamic flow modeling of the brake vacuum booster used in a typical four-wheeled passenger vehicles, under brake apply condition. Vacuum Booster is a key component of brake actuation system whose primary function is to multiply the force received from brake pedal. A hybrid methodology consisting of FEA and 1D simulation of the vacuum booster has been constructed in this study by accommodating its compliance. The brake vacuum booster consists of two chambers, namely vacuum and apply chamber; the force multiplication in vacuum booster occurs because of pressure difference between these two chambers. The hybrid methodology not only captures its flow dynamics but also accommodates the structural interaction that happens between the ratio disc (rigid body) and the reaction disc (hyperelastic body) with the help of finite element analysis, which is the novel part of this project. The result from finite element analysis is then fed into the quasi-static equation of motion of different components of brake vacuum booster modeled using 1D system software, to obtain a typical input load vs output load plot of the same. This study shows 96% correlation between hybrid model and the experimental results for the entire regime of the booster operation. The hybrid model is now used by the designer to obtain the booster performance curve while varying different geometrical parameters, which includes dimension of ratio disc or lap gap and the like.