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Publication numberUS3416459 A
Publication typeGrant
Publication dateDec 17, 1968
Filing dateMay 24, 1966
Priority dateMay 24, 1966
Also published asDE1653880A1, DE1653880B2
Publication numberUS 3416459 A, US 3416459A, US-A-3416459, US3416459 A, US3416459A
InventorsPrijatel Edward A, Reimer Leonard H
Original AssigneeParker Hannifin Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Rotary pump or motor
US 3416459 A
Abstract  available in
Images(5)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

1968 L. H. REIMEIR ETAL 3,4

ROTARY PUMP OR MOTOR Filed May 24, 1966 5 Sheets-Sheet 1' fzgui r INVENTORS LEONARD H. RE/MER EDWARD A. PR/JATEL ATTORNEYS Dec. 17, 1968 RElMER ETAL 3,416,459

ROTARY PUMP 0R MOTOR Filed May 24, 1966 5 Sheets-Sheet 2 F- ?j I INVENTORS LEONARD hL-RE/MER EDWARD A. PR/JATEL VBY ATTORNEYS Dec. 17, 1968 H. REIMER ETAL 3,

ROTARY PUMP OR MOTOR Filed May 24, 1966 5 Sheets-Sheet 3 INVENTORS. LEONARD h. RE/ME'R EDWARD A. PR/c/ATEL ATTORNEYS 1968 1.. H. REIMER ETAL 3,

ROTARY PUMP OR MOTOR Filed May 24, 1966 r 5 Sheets-Sheet 4- ATTORNEYS Dec. 17, 1968 L. H. REIMER ETAL 3,415,459

ROTARY PUMP OR MOTOR Filed May 24, 1966 5 Sheets-Sheet 5 INVENTORS LEONAR H. REM/ER EDWARD A. PR/ 1 EL ATTORNEYS United States Patent 3,416,459 ROTARY PUMP 0R MOTOR Leonard H. Reimer and Edward A. Prijatcl, Lyndhurst,

Ohio, assignors to Parker-Hannifin Corporation, Cleveland, Ohio, a corporation of Ohio Filed May 24, 1966, Ser. No. 552,462 13 Claims. (Cl. 103126) ABSTRACT OF THE DISCLOSURE A gear pump characterized by a passage in the wall of the pump cavity for extending the high pressure zone over a major portion of the cavity, and a flexible wear plate in the housing having an inner face in juxtaposition to the gear faces and an outer face contacted by a seal to provide a compartment opposite the high pressure zone and an intermediate pressure zone in the cavity to which high pressure fluid is introduced for providing a fluid pressure balance on the plate opposite the high pressure zone and an overbalance opposite the intermediate pressure zone tending to flex the plate into sealing engagement with the gear faces.

The present invention relates to a rotary pump or motor and more particularly to a gear pump or motor having means for sealing the gear faces to prevent internal fluid leakage between the high and low pressure zones, and to minimize wear.

Sealing of gear type pumps or motors with the use of a flexible wear plate that is maintained in sealed engagement with the gear faces by introducing fluid pressure behind the plate is generally old and well known. In such known constructions the pressure behind the flexible plate is higher than the pressure in the gear cavity along a substantial portion of the plate so that the plate is maintained in sealing contact with a large portion of the gear side faces. Although this provides an effective seal it also results in considerable friction and hence reduced efliciency.

An object of the present invention is to utilize fluid pressure to press the flexible plate into sealing contact with the gear faces along only a relatively small area, the remaining portions of the plate that are opposite the gear faces having either the same fluid pressure on the two sides thereof, or having a slight unbalance in a direction away from the gear faces, so that such remaining portions of the plate are substantially fluid pressure balanced to avoid being pressed against the gear side faces by fluid pressure whereby friction therebetween is substantially eliminated.

Generally, the above object is attained by substantially balancing a portion of the plate with low pressure and by providing a passage in the wall of the housing for causing high fluid pressure in a major portion of the gear cavity to act on the front side of the flexible wear plate and by providing a compartment on the back side of the flexible wear plate that is opposite such major portion of the gear cavity and that is slightly larger in area than said major portion so as to overlap a relatively small portion of the cavity that is subjected to intermediate pressure whereby the plate will be overbalanced to flex into sealing contact with the gear faces only at such intermediate pressure zone.

Other objects and advantages of the present invention will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed draw- Patented Dec. 17, 1968 ing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.

In such annexed drawing:

FIG. 1 is a side elevation view of a preferred form of pump or motor constructed in accordance with this invention;

FIG. 2 is an end elevation view of the pump of FIG. 1 as seen from the right side thereof looking into the high and low pressure ports;

FIG. 3 is an enlarged longitudinal section taken on the plane of the line 3-3 of FIG. 2;

FIG. 4 is an end elevation view on a reduced scale of the pump or motor of FIG. 3 with the back cover assembly removed as seen from the plane of the line 4-4;

FIG. 5 is an enlarged fragmentary horizontal section taken on the plane of the line 5-5 of FIG. 4;

FIG. 6 is a fragmentary transverse section taken on the plane of the line 6-6 of FIG. 3;

FIG. 7 is an end elevation view on a reduced scale of the front cover assembly as seen from the plane of the line 77 of FIG. 3, showing the configuration of the wear plate which is accurately located in a recess in the inner face of the front cover assembly;

FIG. 8 is a perspective view similar to FIG. 7, but with the wear plate removed and the heat shield and gasket partially broken away to show the seal thereunder;

FIG. 9 is an exploded perspective view of the seal, gasket, heat shield, and wear plate which are adapted to be inserted in the front cover assembly;

FIG. 10 is an enlarged longitudinal section similar to FIG. 3, but of another form of pump or motor in accordance with this invention;

FIG. 11 is a transverse vertical section taken on the plane of the line 11-11 of FIG. 10; and

FIG. 12 is an exploded perspective view similar to FIG. 9 but illustrating the seal-gasket-heat shield of FIGS. 10 and 11 with a modified form of wear plate.

Referring now in detail to the drawing, and first to FIGS. l-9, a form of rotary gear pump in accordance with this invention is generally indicated at 1 and comprises a housing 2 which may include a front cover assembly 3 and back cover assembly 4 with a center section 5 sandwiched therebetween and secured together as by means of suitable bolts 6 and located by dowels 7.

Within center section 5 is a pump cavity 8 of figureeight configurations for receipt of a pair of pumping gears 9 and 10 supported by shafts 11 and 12 journaled in stationary sleeve bushings 13 in the front and rear cover assemblies 3 and 4. Pump cavity 8 includes low and high pressure chambers or zones 15 and 16 respectively communicating with inlet and outlet ports 17 and 18 in the back cover assembly 4. One of the gear shafts 11 has a longitudinal bore 20 therethrough for equalizing the pressure at opposite ends of the shaft 11, while the other gear shaft 12 extends outwardly through the front cover assembly 3 for connection to a suitable prime mover, with a rotary seal 21 surrounding the gear shaft 12 to preclude leakage of fluid therealong. A passage 22 interconnects the shaft receiving bores 23 in the front cover assembly 3.

Leakage of fluid between the mating surfaces of the front and back cover assemblies 3 and 4 center section 5 is precluded by a pair of O-ring seals 25 disposed in ovaloidal grooves 26 in the inner faces of the front and back cover assemblies 3 and 4 which surround the pump cavity 8 and inlet and outlet chamber 15 and 16.

Inner face 27 of one of the cover assemblies 4 is flat for engagement by the adjacent gear faces 28, while the inner face 29 of the other cover assembly 3 has an ovaloidal recess 30 therein that receives a similarly shaped thin wear plate 31 for engagement with the other gear faces 24. Recess is radially spaced from the adjacent groove 26 to provide a groove wall portion 26a for confining O-ring 25. The wear plate 31 may be a laminant consisting of an inner plate 32 of bronze or like metal and a steel backing 33 with holes 34 through the wear plate 31 for passage of the gear shafts 11 and 12.

The back face of the wear plate 31 may be divided into a pair of different sized compartments 35 and 36 by a racetrack type seal 37 with gasket 38 and heat shield 39 interposed between the seal 37 and wear plate 31. All of these parts, the seal 37, gasket 38, and heat shield 39 have an outer configuration identical to the wear plate 31, but they are all skeletonized to provide a circumferentially continuous outer margin 40 and a pair of inner continuous circular portions 41 connected to the outer margin 40 by two angularly disposed fences 42 and 43 and interconnected together by a central fence 44. In this instance compartment 35 comprises compartment sections 35a, 35b, and 350 because these sections are communicated to each other by cutouts 59a and 60a in fence portions 59 and 60 of seal 37. The bottom of the recess 30 is complementally grooved at 45 for receipt of the seal 37, gasket 38, and heat shield 39, but with the heat shield 39 extending slightly out of the groove 45 into the recess 30 as shown in FIGS. 3 and 8 to define with the bottom of the recess 30 and the back face of the wear plate 31 the various compartments 35 and 36. The seal 37 is made of a suitable resilient material such as rubber, while the gasket 38 is preferably made of saturating paper and the heat shield 39 of cotton phenolic, although of course other suitable materials may be used.

Openings 46 and 47 are provided in the wear plate 31 for communicating the compartments 35 and 36 with high pressure chamber 16 and low pressure chamber 15 respectively. The pressure Within the compartment 35 acts on the. wear plate 31 to urge the same toward the adjament gear faces 32 in opposition to the fluid pressure within the pump cavity 8, including the pressure of the fluid within the gear teeth pockets and the fluid film that exists between the side faces of the gears and the wear plate, that is urging the wear plate in a direction away from the gears. Ordinarily, the pressure in the gear cavity increases progressively from the low pressure chamber 15 to the high pressure chamber 16 and with only a single pressure compartment 35 in communication with high pressure chamber 16 there would be a balancing of the pressures on opposite sides of the plate at chamber 16 and a progressive overbalance or differential pressure pushing the plate toward the gears in the region along the unmeshed gear teeth between such high and low pressure chambers 16 and 15. Such progressive differential flexes and presses the plate tightly against the gear teeth so as to effectively seal their side faces but also results in excessive friction and wear of the plate.

In the FIGS. 1 to 9 form high pressure chamber 16 is extended to nearly the area of compartment 35 by providing a radial relief in the pump cavity wall around the gears 9 and 10. This relief 55 provides a space between the outer ends of the gear teeth and pump cavity 8 to connect the gear tooth pockets in this region with high pressure outlet 18 so that these tooth pockets and the fluid film between the adjacent gear teeth and plate 31 have the same high pressure as in chamber 16. Thus, where the compartment 35 and high pressure chamber 16 are opposite each other the fluid pressure forces on the wear plate 31 are balanced. Between the ends 55a of relief 55 and the corners 15a of low pressure chamber 15 the radially outer faces of the gear teeth have a very close fit with the transverse wall of pump cavity 8 and the pressure in the gear teeth pockets between corners 15a and relief ends 550, as well as the fluid film pressure between the adjacent gear teeth of the wear plate, progressively increases the wear from the pump low pressure to the pump high pressure to provide a zone of increasing pressure in cavity 8. Compartment 36 has a portion thereof opposite low pressure chamber 15 and has other portions B opposite such zones of increasing pressure in cavity 8. The pressure in compartment 36 is uniform throughout and is the same as in low pressure chamber 15. The fluid pressure on the opposite sides of wear plate in the region of low pressure chamber 15 are therefore balanced but the fluid pressures in cavity 8 in the regions designated B are somewhat higher than in the corresponding portions of compartment 36 and therefore tend to flex plate 31 away from the gear side faces in such B regions and consequently there is little or no friction between the gear side faces and the wear plate in such regions. Even though there is a tendency for the fluid pressure to lift the wear plate from the gears at such B regions, the plate actually remains closely adjacent the gear side faces because of its inherent resistance to flexing.

In the region of compartment 35b designated A, the fluid is under the same high pressure as the remainder of compartment 35b but the pressure in the corresponding portion of the cavity 8 is somewhat less, that is, it is an intermediate pressure, because of the above described gradient or progressive increase in pressure between cavity corners 15a and relief ends 55a. This provides a differential or overbalance pressure on the portion of plate 31 in regions A tending to press the same against the gear teeth side faces to provide an effective seal therebetween.

Thus, as described above, reliefs 55 and compartments 35 and 36 cooperate to provide a pump arrangement in which most of the area of the wear plate is either fluid pressure balanced or slightly fluid pressure overbalanced in a direction tending to unseat the plate from the gear teeth side faces and only a small area A of the plate is subject to a differential in compartment pressure as compared to correspondingly located pump cavity pressure that acts to press such small area of the plate into sealing contact with the gear teeth side faces. Because there is high pressure in the channel of fences 42 and an intermediate gradient pressure in cavity 8 therebeneath there is also an overbalance force on the wear plate in this location. In the manner described, the gear side faces are effectively sealed between the low and high pressure chambers 15 and 16 at a relatively small area of the plate as that friction and wear between the plate and gear side faces is minimized.

For maintaining the seal 37, gasket 38 and heat shield 39 in fluid tight engagement with the wear plate 31 to preclude leakage of fluid between compartments 35 and 36, the outer face of the seal 37 has a composite groove or channel 57 formed therein which may be supplied with high fluid pressure through additional openings 58 in the wear plate 31 communicating with cutouts 59a and 60a of fence portions 59 and 60 on the seal 37 located in complemental grooves 61 in the front cover assembly 3. Alternatively, the additional wear plate openings 58 may be eliminated, since high fluid pressure will still be supplied to the seal channel 57 from the compartment 35 via the grooves 61 in the front cover assembly 3 and cutouts 59a and 60a. Or the additional fences 59 and 60 may be left intact and the seal 37, gasket 38, heat shield 39' and Wear plate 31' provided with aligned apertures 62 communicating the seal channel '57 with high pressure chamber 16 in the pump cavity 8', as in the FIGS. 10 and 11 embodiment.

As seen in FIGS. 3 and 5, the grooves 45, 61 in the front cover assembly 3 are stepped at 63, while the inner and outer seal lips 64 and 65 which define the seal channel 57 are of the same length, However, the outer lip 65 is thicker than the inner lip 64 and is squeezed somewhat by engagement with the top 66 of the step 63 to provide a slight mechanical loading of the wear plate 31 against the center section 5 and form a pressure pocket 67 in which the pressure expands the lips 64 and 65 into sealed engagement with the walls of the grooves and, in addition, applies a further sealing force against the wear plate 31.

The openings 46 and 47 in the wear plate 31, besides supplying high and low fluid pressure to the compartments 35 and 36 as aforesaid, also provide anti-trapping reliefs to facilitate engagement and disengagement of the pump gears 9 and 10. Moreover, depressions 68'may be formed in the inner face of the wear plate 31 to provide lubrication for the gear faces during operation.

In FIGS. 10 and 11 there is illustrated another form of pump 1 in accordance with this invention which is quite similar to the pump 1 already described and accordingly like reference numerals followed by a prime symbol are used to designate like parts. However, the large high pressure compartment 35' is divided into three smaller compartments 70, 71 and 72 preferably by leaving the seal fences 59' and 60' intact and providing corresponding fences 59 and 60' on the gasket 38' and heat shield 39. Moreover, the relief 55 has been eliminated and instead the adjacent gear teeth pockets and side faces are communicated with high pressure chamber 16" by means of sickle shaped grooves 75 in the inner face of the back cover assembly 4' which extend from chamber 16 to about the middle of the intermediate compartments 71 and 72. Apertures 76 in the wear plate 31' interconnect the sickle grooves 75 and intermediate compartments 71 and 72 across the rotating gears. As in the case of reliefs 55, sickle grooves 75 eliminate rising pressure in the gear tooth pockets adjacent thereto and the pressure in such pockets and the fluid film pressure between the adjacent gear teeth side faces and the wear plate will be the same as in high pressure chamber 16. In this case the fluid pressures acting on opposite sides of the wear plate will be balanced in the regions of compartment 35' and those portions of compartments 71, 72 to the right of the portions designated C in FIG. 11 and will be overbalanced in a direction to press the plate against the gears in such portions designated C. The fluid pressure efiect on the plate in the region of compartment 36 is the same as in connection with compartment 36 of'FIG. 6.

In FIG. 12 the seal 37', the gasket 38 and the heat shield 33' are the same as in FIGS. 10 and 11 and either the sickle grooves 75 or the relief 55 may be used in the housing. The wear plate 80, however, differs from the wear plate 31' in that the slot 46 on the high pressure side has been omitted and slots 81, 82 are substituted. These slots 81, *82 :are over and extend to either side of fences 59', 60 so as to direct high pressure fluid from pump cavity 8 to compartments 71, 72 and 75. The fluid pressures acting on wear plate 80 in the regions of these compartments are thus the same as in connection with FIG. 11. Thus in all forms of the invention herein disclosed, substantially equal and relatively large areas on opposite sides of the wear plate 31, 31' or 80 are exposed to high outlet pressure so as to be fluid pressure balanced, and relatively small areas at intermediate pressure zones A or C of the pump cavity are overbalanced by outlet pressure in the opposed portions of the compartment behind the wear plate. In addition, opposite areas of other portions of the plates are exposed to either low inlet pressure or to pressures somewhat higher than inlet pressure whereby such other portions are either balanced or have a slight tendency to move away from the gear side faces. In this way, the wear plate 31, 31', or '80 is flexed by moderate fluid pressure differential acting on relatively small areas against the gear faces to effect proper sealing but without excessive friction and wear.

All three forms of the invention permit rotation of the driving gear 10 in either direction without substituting new parts. When the parts are assembled as illustrated in the drawings, driving gear 10 rotates in a clockwise direction as viewed in FIG. 4 and driven gear 9 rotates in a counterclockwise -direction. To have driving gear 10 rotate counterclockwise it is only necessary to switch places with gear 9. To do this in the FIG. 1-9 form, for example, cover 3, seal 37, heat shield 38, gasket 39 and wear plate 31 are first removed, these parts remaining together during removal.

Gears 5 and 10 are then interchanged. Seal 37, heat shield 38, gasket 39 and wear plate 31 are then rotated within cover 3 and the cover, with these parts therein, is rotated 180 and reassembled against center section 5. Now driving gear 10 is in the upper position, as viewed in FIG. 4, and is rotated counterclockwise for pumping fluid from inlet chamber 15 to outlet chamber 16. The wear plate, seal, heat shield, and gasket are in their original positions relative to center section 5 and therefore fluid pressure will act thereon in the same manner as already described.

Other modes'of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

We, therefore, particularly point out and distinctly claim as our invention: 1

1. A gear pump comprising a housing having a cavity that includes inlet and outlet chambers, gears rotatable in said cavity to pump fluid from the inlet chamber to the outlet chamben a wear plate in the housing having an inner face adjacent one side of said gears, seal means in said housing contacting the outer face of said wear plate and forming with the same a plurality of compartments, said seal meanshaving a channel therein opening away from the wear plate, passage means for communicating said compartments with selected zones of said pump cavity, and aligned passages through said wear plate and the bottom wall'of said channel for conducting fluid from said outlet chamber to said channel where it exerts pressure on said seal means urging the same into contact with the wear plate.

2. The pump of claim 1 in which there is only a single passage through the bottom wall of said channel.

3. A rotary pump comprising a housing having a cavity including inlet and outlet ports, intermeshing gears rotatable in said cavity to generate pressure influid conveyed thereby from said inlet port to said outlet port, a flexible wear plate in said housing having an inner face in juxtaposition to adjacent gear faces, skeletonized seal means in sealed contact with said housing and with the outer face of said wear plate for providing between said housing and said wear plate at least two compartments in fluid communication with the fluid pressure in said outlet port and with the fluid pressure in said inlet port respectively, the wall of said cavity removed from said wear plate having passage means extending the high pressure zone of said cavity from said outlet port around a major portion of the peripheral portions of said gears adjacent to successive intermediate pressure and low pressure zones extending from said high pressure zone to said inlet port, the compartment in communication with said outlet port being opposite tojsaid high pressure zone and circumferentially overlapping said intermediate pressure zones, and the compartment in communication with said inlet port being opposite to said low pressure zone, whereby said wear plate is pressure balanced in said high pressure zone, pressure overbalanced in the portions which overlap said intermediate pressure zones, and pressure under balanced in said low pressure zone, the pressure overbalancing being in relatively small areas of said wear plate to flex the latter thereat into sealing engagement with the adjacent gear faces there-at.

4. A gear pump comprising a housing having a cavity, gears rotatable in said cavity to provide adjacent intermediate and high fluid pressure zones in said cavity, a flexible wear plate in said housing having an inner face in juxtaposition to adjacent gear faces, passage means in the wall of said cavity removed from said wear plate for extending said high pressure zone over a major portion of said cavity, seal means in said housing contacting the outer face of said wear plate for providing compartment means opposite to said high pressure and intermediate pressure zones, and means for introducing high pressure fluid from said high pressure zone into said compartment means whereby the portion of said plate opposite said high pressure zone of said cavity is fluid pressure balanced and the portion of said plate opposite said intermediate pressure zone is overbalanced so as to flex said latter portion of said plate into sealing engagament with said gear faces.

5. The pump of claim 4 wherein said passage means comprises a radial relief in the peripheral wall of said cavity.

6. The pump of claim 4 wherein said passage means comprises a groove formed in the wall of said cavity that is opposite said wear plate.

7. The pump of claim 4 wherein said compartment means comprises separate sections, and there are apertures in said wear plate communicating said compartment sections with said high pressure zone.

8. The pump of claim 4 wherein said compartment means comprises separate sections, and there are slots through said wear plate each connecting two of said sections with said high pressure zone.

9. The pump of claim 4 wherein said seal means is skeletonized to provide said compartment means, there is a channel in the back face of said seal means which is supplied with fluid from said high pressure zone for maintaining said seal means in fluid-tight engagement with said wear plate, and aligned apertures are provided in said seal means and wear plate for supplying such fluid from said high pressure zone to said channel as aforesaid.

10. The pump of claim 4 wherein said seal means is skeletonized to provide said compartment means, there is a channel in the back face of said seal means which is supplied with fluid from said high pressure zone for maintaining said seal means in fluid-tight engagement with said wear plate, portions of said seal means are cut away through said channel, and there are apertures in said wear plate in alignment with said cutaway portions for supplying fluid from said high pressure zone to said channel through said cutaway portions.

11. The pump of claim 3 wherein said seal means is disposed in a groove in said housing, and there are aligned passages in said plate and seal means for conducting fluid from said high pressure zone of said cavity to said groove to urge said seal means against the outer face of said wear plate, said seal means being of channel-shaped crosssection providing axial lips which are retained in sealed engagement with the side walls of said groove by such fluid pressure in said groove.

12. The pump of claim 3 wherein said lips are of substantially equal length and said groove has a stepped bottom wall arranged to axially squeeze one of said lips between said bottom wall and the outer face of said wear plate, the other of said lips being spaced from said bottom wall, and said one lip being radially thicker than said other lip.

13. The pump of claim 3 wherein said compartment in communication with said outlet port circumferentially overlaps only a portion of said intermediate pressure zones, and said compartment in communication with said inlet port circumferentially overlaps another portion of said intermediate pressure zones, whereby said wear plate is pressure overbalanced in the portion of said intermediate pressure zones opposite said compartment in communication with said outlet port and pressure underbalanced in the portion of said intermediate pressure zones opposite said compartment in communication with said inlet port.

References Cited UNITED STATES PATENTS 2,644,701 7/1953 Flick 277205 XR 2,809,592 10/1957 Miller et a1. 2,993,450 7/1961 Weigert. 3,057,303 10/1962 Lauck. 3,101,673 8/1963 Clark et :11. 3,153,371 10/1964 Miller. 3,294,029 12/1966 Clark et al.

FOREIGN PATENTS 1,121,180 7/1956 France.

FRED C. MATTERN, 111., Primary Examiner.

T. R. HAMPSHIRE, Assistant Examiner.

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3499390 *Apr 11, 1968Mar 10, 1970Parker Hannifin CorpRotary pump
US4239468 *Sep 8, 1978Dec 16, 1980The Rexroth CorporationApparatus for controlling pressure distribution in gear pump
US5022837 *Nov 13, 1989Jun 11, 1991Sta-Rite Industries, Inc.Seal arrangement for a gear machine
US6152715 *Jan 30, 1998Nov 28, 2000Kaempe; Staffan I.Pressure clamped hydraulic pump
US6413064 *Aug 13, 1999Jul 2, 2002Luk Fahrzeug-Hydraulik Gmbh & Co. KgPump
US7074025 *Apr 10, 2004Jul 11, 2006Luk Lamellen Und Kupplungsbau Beteiligungs KgFluid delivery device
US7972126Jan 19, 2006Jul 5, 2011Trw Automotive GmbhPower steering system hydraulic pump
US8235691 *May 21, 2009Aug 7, 2012Roper Pump CompanyDual displacement external gear pump
US20090297384 *May 21, 2009Dec 3, 2009Roper Pump CompanyDual displacement external gear pump
CN101107448BJan 19, 2006Jul 14, 2010Trw汽车股份有限公司Hydraulic pump for a power steering system
WO2001038739A1 *Nov 10, 2000May 31, 2001Bodzak StanislawDevice for reducing the axial load of a pump which delivers fluid
WO2006077121A1 *Jan 19, 2006Jul 27, 2006Trw Automotive GmbhHydraulic pump for a power steering system
Classifications
U.S. Classification418/132, 418/149
International ClassificationF04C15/00
Cooperative ClassificationF04C15/0026
European ClassificationF04C15/00B4B