Patent ID: 8231182

Claim:
A method for creating low pressure in a brake activation device of a motor vehicle brake system comprising (i) a pneumatic brake force booster having an interior that is divided into at least one low-pressure chamber and one working chamber, (ii) a brake master cylinder, and (iii) a pneumatic motor pump unit including a low-pressure pump and a motor that is configured to drive the low-pressure pump to create a low pressure in the low-pressure chamber, the method comprising the steps of: detecting either a low-pressure level (P) in the low-pressure chamber or a pressure difference between the low-pressure chamber and the working chamber; activating the motor pump unit if the pressure falls below a first predefined, lower low- pressure level (Pe) in the low-pressure chamber; deactivating the motor pump unit if the pressure reaches a second predetermined, upper low-pressure level (Pa); and controlling the first predefined, lower low-pressure level (Pe) and the second predefined, upper low-pressure level (Pa) in the low-pressure chamber as a function of a speed (v) of the vehicle.