# US 2018/0023560 A1 · Tolerance independent crescent internal gear pump > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0023560 A1 - Document ID: US20180023560A1 - Status: Published application - Kind: A1 - Application number: 15/548,296 - Filed: 2015-02-05 - Published: 2018-01-25 - Earliest claimed: 2015-02-05 - Assignees: IMO Industries, Inc. - Applicants: IMO Industries, Inc. - Inventors: Patrick Wilson Duncan; Colette Doll Greene; Philip Taylor Alexander - Web page: https://patentgrep.com/patent/US20180023560A1 ## CPC - F04C 2/101: {with a crescent-shaped filler element, located between the inner and outer intermeshing members} - F04C 2/102: {the two members rotating simultaneously around their respective axes} - F04C 15/0019: {Radial sealing elements specially adapted for intermeshing-engagement type machines or pumps, e.g. gear machines or pumps} - F04C 2230/10: by removing material - F04C 2230/60: Assembly methods - F04C 2230/602: Gap; Clearance - F04C: ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS (engines F03C); ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS ## Abstract A crescent internal gear pump includes a front cover, an end cover, a ring gear and a pinion gear disposed within a gear housing in an eccentric, intermeshing relationship. The housing is disposed intermediate the front cover and the end cover. A crescent is disposed radially intermediate the ring gear and the pinion gear. The crescent partially extends into a correspondingly shaped slot in the end cover. The gear housing, the ring gear, and the pinion gear can have substantially the same thickness. A shim can be disposed intermediate the end cover and the gear housing for establishing a desired clearance therebetween. ## Claims ### Claim 1 A crescent internal gear pump comprising: a front cover; an end cover having a slot therein; a gear housing disposed between the front cover and the end cover; a ring gear and a pinion gear disposed within the gear housing in an eccentric, intermeshing relationship; and a crescent disposed radially intermediate the ring gear and the pinion gear; wherein a portion of the crescent extends into the slot in the end cover. ### Claim 2 (depends on 1) The crescent internal gear pump of claim 1, wherein the crescent is moveable into and out of the slot. ### Claim 3 (depends on 1) The crescent internal gear pump of claim 1, wherein a front face of the crescent engages with the front cover. ### Claim 4 (depends on 1) The crescent internal gear pump of claim 1, wherein the crescent is press-fit into the slot and forms a fluid tight seal with the end cover. ### Claim 5 (depends on 1) The crescent internal gear pump of claim 1, wherein the slot has a cross-sectional shape that is substantially the same as a cross-sectional shape of the crescent. ### Claim 6 (depends on 1) The crescent internal gear pump of claim 1, further comprising a biasing member disposed with the slot and configured to forcibly hold the crescent in engagement with the front cover. ### Claim 7 (depends on 1) The crescent internal gear pump of claim 1, further comprising a shim disposed intermediate the gear housing and the end cover. ### Claim 8 (depends on 7) The crescent internal gear pump of claim 7, wherein the shim has a thickness selected to establish a predetermined clearance between the gear housing and the end cover. ### Claim 9 (depends on 7) The crescent internal gear pump of claim 7, wherein the shim has a thickness selected to establish a predetermined clearance between the end cover and the ring and pinion gears and between the front cover and the ring and pinion gears. ### Claim 10 (depends on 1) The crescent internal gear pump of claim 1, wherein the gear housing, the ring gear, and the pinion gear have substantially the same thickness. ### Claim 11 A method of manufacturing a crescent internal gear pump having a gear housing, a ring gear, a pinion gear, a front cover, and an end cover, the method comprising: providing the gear housing, the ring gear, the pinion gear, the front cover, and the end cover as separate components, wherein the gear housing, the ring gear, the pinion gear, the front cover, and the end cover all have substantially the same thickness; and providing the crescent with a length is greater than the thicknesses of the gear housing, the ring gear, and the pinion gear. ### Claim 12 (depends on 11) The method of claim 11, further comprising providing the end cover with a slot shaped to receive the crescent. ### Claim 13 (depends on 11) The method of claim 11, further comprising match grinding the gear housing, the ring gear, and the pinion gear to achieve the substantially same thickness. ### Claim 14 (depends on 11) The method of claim 11, further comprising inserting a first portion of the crescent into a correspondingly shaped slot in the end cover, wherein a length of a second portion of the crescent that protrudes from the slot is greater than the thicknesses of the gear housing, the ring gear, and the pinion gear. ### Claim 15 (depends on 14) The method of claim 14, further comprising disposing a biasing member in the slot, the biasing member configured to bias the crescent away from the end cover. ### Claim 16 (depends on 14) The method of claim 14, further comprising preliminarily assembling the gear housing, the ring gear, the pinion gear, the front cover, and the end cover using fasteners, whereby a front face of the crescent is brought into engagement with the front cover. ### Claim 17 (depends on 16) The method of claim 16, further comprising tightening the fasteners to draw the gear housing, the ring gear, the pinion gear, the front cover, and the end cover into secure longitudinal engagement, whereby the front cover forcibly drives the crescent further into the slot. ### Claim 18 (depends on 16) The method of claim 16, wherein the step of preliminary assembling the gear housing, the ring gear, the pinion gear, the front cover, and the end cover further comprises disposing a shim intermediate the end cover and the gear housing. ### Claim 19 (depends on 18) The method of claim 18, further comprising selecting the shim with a predetermined thickness to establish a desired clearance between the gear housing and the end cover. ### Claim 20 (depends on 18) The method of claim 18, further comprising selecting the shim with a predetermined thickness to establish a desired clearance between the end cover and the ring and pinion gears and between the front cover and the ring and pinion gears.