Pump assembly for a hydraulic brake system for motor vehicles

摘要

The pump assembly (1) supplies the brake booster (7) of a brake system with pressure medium when actuated. For adjusting the delivery to the volumetric requirement of the brake system and for improved utilisation of the drive power of an electric motor (5) the pump assembly (1) comprises two pressure medium pumps (2, 3), which are driven by the electric motor (5) from a common drive shaft (4). Once a predetermined delivery pressure is attained, the pressure medium pump (3) is switched to circulation at zero pressure by a pressure-controlled 2/2 way valve (9), as a result of which the delivery and the drive power of the pump assembly (1) are reduced. <IMAGE>