Adjustable positive-displacement pump for servo steering system of motor vehicle, has inserting unit inserted at inner surface of curve ring and designed such that sliding friction between rotor units and contact surface is reduced

摘要

The pump has a housing (1) supporting a rotor set (2) that is formed from a rotor (3), rotor units (4) and a curve ring (5). A working chamber (7) is divided into working cells (8) by the rotor units. An inserting unit (11) is inserted at an inner surface of the curve ring. An inner surface of the inserting unit forms a contact surface (12) for the rotor units, and is turned away from the curve ring. The inserting unit is designed, such that a sliding friction between the rotor units and the contact surface is reduced, and is made of a gray cast iron and a nodular graphite gray cast iron.