US 4,056,337 AGranted

External gear type fluid displacing machine with bearing gap

AssigneeRobert Bosch GmbH

InventorsJurgen Zorn, Jan Vlemmings, Karl-Heinz Muller, Siegfried Mayer, Wilhelm Dworak, Eugen Hartmann, Martin Fader, Wolfgang Talmon, Claus Jons, Ivan Sauer, Paul Bosch

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Abstract

An external gear type hydraulic pump or motor wherein the trunnions of gears in the chamber of the housing are surrounded by annular bearing members. The peripheral surface of each bearing member defines with the adjacent internal surface of the housing an arcuate gap whose width increases in a direction toward the respective end face of the corresponding gear. To this end, portions of or the entire peripheral surfaces of bearing members and/or portions of or the entire internal surfaces of the housing have a conical or spherical shape. The gaps are located in the low-pressure zone and reduce the likelihood of wear upon those end faces of bearing members which are adjacent to the end faces of the gears because the bearing members can tilt in response to increasing load without localized rubbing against the gears. Additional gaps can be provided between the end faces of the gears and the adjacent end faces of the bearing members to further reduce the likelihood of uneven wear upon the bearing members.

Claims13

Dependent claims

In an external gear type fluid displacing machine, a combination comprising a housing having a chamber;

a pair of mating gears in said chamber, each of said gears having at least one trunnion and a first end face adjacent to said trunnion;
and annular bearing members surrounding said trunnions and each having a second end face opposite one of said first end faces extending in the radial direction at least over a substantial portion of the radial extent of said first end face and also having an outer peripheral surface, said housing having internal surfaces adjacent to and defining with the outer peripheral surfaces of the bearing members, when the machine is not in operation, arcuate gaps extending at least over a major portion of the length of said bearing members and having cross-sectional areas gradually increasing toward the end faces of the respective gears, said bearing members being in operation subject to tilting with resulting radial upsetting and axial elongation of the bearing members, said tilting causing formation of axial clearances between said first and second end faces which compensate for said axial elongation and at least reduce frictional wear between said first and second end faces.

Dependencies are inferred from the claim text.