A study on the development of a numerical model for a rotary vane vacuum pump for brake boosters

Abstract

A negative pressure is formed inside the brake booster in a running diesel vehicle by using a rotary vane vacuum pump. In vacuum pump design, it is important to reduce the time required to induce the minimum negative pressure required for immediate consecutive braking and to reduce the torque used to drive the pump. In this study, a numerical simulation model to predict the performance of a vacuum pump was developed and experimentally validated by comparing the pump’s drive torque and the time required by a 4 L chamber to reach the target pressure. The housing profile was obtained via 3D scanning, while the check valve, bypass hole, and groove, which significantly affect the pump performance, were mathematically described. The model was validated by comparing the vacuum chamber pressure variation and the average torque. Similarly, the pump performance with respect to changes in major design factors, such as check valve and bypass hole shapes, were compared against the experimental data. In addition, the pump performance was predicted as a function of the housing profile shape, which is difficult to evaluate experimentally, and a new profile shape to improve the performance was proposed.