# US 9,752,575 B2 · Two stage pump, particularly provided as main pump for supplying an aircraft engine with fuel > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,752,575 B2 - Document ID: US9752575B2 - Status: Granted - Kind: B2 - Application number: 14/750,121 - Filed: 2015-06-25 - Published: 2015-12-31 - Granted: 2017-09-05 - Earliest claimed: 2014-06-26 - Assignees: Snecma - Applicants: Snecma - Inventors: Philippe Vertenoeuil - Web page: https://patentgrep.com/patent/US9752575B2 ## CPC - F04C 11/005: {of dissimilar working principle} - F02M 37/041: {Arrangements for driving gear-type pumps} - F04C 2/084: {Toothed wheels} - F04C 2/14: with toothed rotary pistons - F04C 2/18: with similar tooth forms (F04C2/16 takes precedence) - F04C 11/001: {of similar working principle} - F04C 11/006: {having complementary function} - F04C 13/001: {Pumps for particular liquids} - F04C 15/0061: {Means for transmitting movement from the prime mover to driven parts of the pump, e.g. clutches, couplings, transmissions} - F04D 13/12: Combinations of two or more pumps (combinations with priming pumps or booster pumps to counteract vapour-lock F04D9/04) - F04C 2210/1044: Fuel - F04C 2210/203: Fuel - F04C 2240/54: Hydrostatic or hydrodynamic bearing assemblies specially adapted for rotary positive displacement pumps or compressors - F04C 2240/60: Shafts - F04C: ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS (engines F03C); ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS - F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) ## Abstract A two stage pump (2′, 4′), where the high pressure stage (4′) is a gear pump (11, 12), comprises a driving of the other stage (2′) by a support shaft (74), mounted in the driven pinion (12), the shaft (74) being driven by the drive shaft (21), by means of a pair of toothed wheels (77, 79) adjacent to the rest of the stage (4′), which can allow different rotation speeds between the two stages (2′, 4′). The support shaft (74) may be supported by stops and hydrodynamic bearings, directly integrated and lubricated in the driven pinion, which make the design lighter and more compact. The shaft (74) and the toothed wheels (77, 79) ingeniously transmit the loads from the stage (2′) to the stage (4′) in such a way as to cancel out the usual hydraulic loads, stemming from pressure, and mechanical, forces stemming from rotational drivings on the driven pinion (12). ## Claims ### Claim 1 Two stage pump including a first pump having a rotating pumping element driven by a support shaft, a second pump including two pumping pinions meshing together, the two pumping pinions including a driving pinion and a driven pinion, a drive shaft of the driving pinion extending along a longitudinal axis, and a transmission connecting the driving pinion to the support shaft, the transmission being contained in the second pump, the support shaft being coaxial to the driven pinion, wherein the support shaft is partially contained in a reaming passing through the driven pinion, and in that it comprises a first bearing supporting the support shaft in the reaming, formed between the support shaft and the driven pinion. ### Claim 2 (depends on 1) Two stage pump according to claim 1, wherein the first bearing comprises a first axial stop, and the support shaft and the reaming are provided with radial projections having opposite faces that are either flat, or, preferably, conical. ### Claim 3 (depends on 2) Two stage pump according to claim 2, wherein the first axial stop is hydrodynamic and maintained by re-circulations of a fluid pumped in one of the two pumps. ### Claim 4 (depends on 1) Two stage pump according to claim 1, wherein it includes a sealing gasket arranged around the support shaft, separating the pumping element of the first pump from the second pump, the sealing gasket forming a second bearing supporting the support shaft. ### Claim 5 (depends on 4) Two stage pump according to claim 4, wherein the second bearing is hydrodynamic and maintained by re-circulations of a fluid pumped in one of the two pumps. ### Claim 6 (depends on 4) Two stage pump according to claim 4, wherein the transmission consists of a first toothed wheel and a second toothed wheel, respectively integral with the driving pinion and the support shaft and meshing together. ### Claim 7 (depends on 6) Two stage pump according to claim 6, wherein the sealing gasket is arranged between a flange of a casing of the two stage pump and the second toothed wheel, the flange separating respective chambers of the first pump and the second pump. ### Claim 8 (depends on 1) Two stage pump according to claim 1, wherein the transmission consists of a first toothed wheel and a second toothed wheel, respectively integral with the driving pinion and the support shaft and meshing together. ### Claim 9 (depends on 8) Two stage pump according to claim 8, wherein the second toothed wheel and a support bearing of the driven pinion have respective elements which cooperate to form a second axial stop. ### Claim 10 (depends on 9) Two stage pump according to claim 9, wherein the second axial stop is hydrodynamic and maintained by re-circulations of a fluid pumped in one of the two pumps. ### Claim 11 (depends on 8) Two stage pump according to claim 8, whrein the transmission further includes a sleeve integral with the first toothed wheel and sunk into a reaming of the driving pinion. ### Claim 12 (depends on 1) Two stage pump according to claim 1, wherein the first bearing is hydrodynamic and maintained by re-circulations of a fluid pumped in one of the two pumps. ### Claim 13 (depends on 1) Two stage pump according to claim 1, wherein the rotating pumping element includes a fluid outlet volute of changing shape, which is arranged so as to exert on the support shaft a load of constant orientation towards the driving pinion.