Gerotor liquid pump mounted on a support bushing

Claim 1

A liquid pump for liquids having a low viscosity, including water, alcohols or other chemicals of the type which includes a gear unit mounted in a housing which has an outer gear and an inner gear eccentrically mounted with respect to said outer gear forming variable spaces between the gear teeth, said inner gear being driven by a shaft, the improvement comprising: (a) a bushing on which said inner gear of said gear unit is mounted, the length of said bushing in the axial direction being longer than the width of said inner gear, said bushing also having axially extending bores therethrough so that an oil exchange takes place between the bushing sides through said bores, (b) pump coupling chambers in said housing for the pressure and suction sides of the pump disposed on one axial side of said gears, (c) relief pockets formed in said housing on the other axial side of said gears, which communicate with said pump coupling chambers via said spaces between said teeth of said outer and inner gears, (d) a central support bolt on which said bushing is mounted having hydrostatic support pockets formed in the peripheral surface thereof beneath said bushing and conduit means for connecting said support pockets to the pump coupling chambers, the length of said support pockets in the axial direction being longer than the axial width of said inner gear, the lengths of said bushing and support pockets being determined by the required hydrostatic support forces in such a manner that the support forces lie directly in the effective plane of the hydraulic radial forces, said support bolt also having a central bore for carrying out any leakage discharge.