Patent ID: 7909413

Claim:
A method for providing vacuum for a brake actuation device of a motor vehicle brake system comprising a pneumatic brake booster ( 1 ), the interior of which is subdivided into at least one vacuum chamber and one working chamber, the system further comprising a master brake cylinder ( 2 ) and a pneumatic motor-and-pump assembly ( 3 ) with a vacuum pump ( 6 ) and a motor ( 7 ) driving the vacuum pump ( 6 ), the method comprising the steps of sensing a vacuum level in the vacuum chamber or a difference in pressure between the vacuum chamber and the working chamber using a sensor ( 9 ), enabling the motor-and-pump assembly ( 3 ) by an electronic control unit ( 12 ) when the vacuum falls below a defined bottom vacuum level (Pe) in the vacuum chamber, controlling a rotational speed (np) of the motor-and-pump assembly ( 3 ) depending on driving conditions of the vehicle, and disabling the motor-and-pump assembly when a defined top vacuum level (Pa) is reached, wherein during a start period of the vehicle drive, the motor-and-pump assembly ( 3 ) is operated at a maximum rotational speed (np max ) until the defined bottom vacuum level (Pe) is reached, and is operated subsequently at an optimized rotational speed (np opt ) until the top vacuum level (Pa) is reached.