Displacement pump e.g. oil pump, for supplying oil to lubricate internal combustion engine of motor car, has rotor comprising recess inserted into chamber wall and retaining part of operating medium in chamber in standstill state of pump

摘要

The pump has a cylindrical rotor (11) arranged within a pump housing (10). The rotor comprises a chamber wall (13) turned toward the pump housing for radial limitation of a chamber (12) to retain an operating medium. The rotor comprises a radial outwardly aligned recess (14) i.e. groove, inserted into the chamber wall. The recess retains a part of the operating medium in the chamber in a standstill state of the pump. Diameter of the recess is smaller than 12 mm, and depth of the recess is larger than 2 mm. The pump housing has an inner wall (15) turned toward the chamber wall. The pump housing is formed as a hollow cylinder.