Hydraulic unit for a vehicle brake system

Abstract

A hydraulic unit for a vehicle brake system that enables limiting wheel brake slip is known. To that end, the hydraulic unit has at least one piston pump, which is drivable by an electric motor and empties a reservoir that is filled on the occasion of the limitation of wheel brake slip. This reservoir comprises a cylinder, embodied in the manner of a blind bore, as well as a piston that divides a storage chamber from a spring chamber in the cylinder, a spring, and a closure element that prevents water from entering the cylinder if the hydraulic unit should become immersed in water. A pressure equalization conduit begins at the spring chamber and leads into the interior of the motor, so that a displacement of the piston for taking up pressure fluid in the storage chamber is effected essentially only by friction of the piston and forces of the spring. A conduit is also provided, by means of which pressure fluid that emerges from the piston pump at the eccentric can be carried away. The invention proposes connecting the spring chamber of the reservoir to the conduit that carries the pressure fluid away. The spring chamber forms a collection container for pressure fluid, as a result of which the collection of the pressure fluid takes place far away from electrical components of the hydraulic unit, and especially of the motor, thus avoiding electrical defects.