US2996998A

US2996998A - Pump

Info

Publication number: US2996998A
Application number: US685980A
Authority: US
Inventors: Gold Harol; David M Straight
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-09-24
Filing date: 1957-09-24
Publication date: 1961-08-22
Anticipated expiration: 1978-08-22

Description

Aug. 22, 1961 H. GOLD ET AL 2 Sheets-Sheet 1 Filed Sept. 24, 1957 United tates 2,996,998 PUMP This invention relates to fluid pumps and particularly to the class of gear pumps generally referred to as pressure-loaded gear pumps. The function of pressure loading in gear pumps is to reduce internal pump leakage from the pump discharge side to the pump inlet side. The present invention provides a pressure-loaded gear pump construction which reduces internal pump leakage to a marked extent as compared with prior art constructions.

It is a general object of the present invention to provide novel and improved fluid pump construction.

A further object of the invention is to provide a fluid pump having markedly reduced internal leakage from the pump discharge side to the pump inlet side.

Another object of the invention is to provide a pressureloaded gear pump which is simpler to manufacture.

Yet another object of the invention is to provide a pressure-loaded gear pump which affords important cost savings in manufacture.

Other and further important objects, features and advantages of the present invention will be apparent from the following detailed description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a front elevational view of a pressureloaded gear pump in accordance with the present invention;

FIGURE 2 is a longitudinal sectional view taken generally along the line II-II of FIGURE 1;

FIGURE 3 is a horizontal sectional view taken generally along the line III-III of FIGURE 2;

FIGURE 4 is a cross sectional view taken generally along the line IVIV of FIGURE 2;

FIGURE 5 is a cross sectional view taken generally along the line VV of FIGURE 2; and

FIGURE 6 is a cross sectional view taken generally along the line VI-VI in FIGURE 3, the view being rotated 90 counterclockwise with respect to the orientation of FIGURE 1.

As shown on the drawings:

By way of illustration of a preferred embodiment of the present invention, a pressure-loaded gear pump is illustrated comprising a housing 10 including housing parts 11 and 12 secured together by means of screws such as indicated at 13. The front housing part 11 may have a mounting flange 11a provided with suitable mounting bolt-holes 11b and a conventional aligning shoulder 11h.

The housing part 11 is provided with an internal cavity as generally indicated at 15 in FIGURE 5 which is defined by an internal wall of the housing part 11 including semi-cylindrical interior wall portions 11c and 11d, vertical planar interior wall portions 112 and 11 connecting respective margins of the semi-cylindrical wall portions 110 and 11d, and an interior side wall portion 11g, FIG- URE 2. 7

It will be observed from FIGURE 3, that the housing part 12 has an inlet passage 21 communicating with an inlet passage 22 in the housing part 11, which in turn communicates with a pump inlet chamber indicated at 24 in FIGURE 5. A discharge passage 26 in housing part 12 communicates with a pump discharge chamber 27 in the cavity indicated at 15 in FIGURE 5.

For impelling fluid between inlet chamber 24 and outlet chamber 27 and preferably developing a pressure atent 1 2,9%,99 Patented Aug. 22, 1961 differential between these chambers in operation, a pair of

impeller elements

31 and 32 are mounted in the cavity 15 with their axes generally coinciding with the centers of curvature of the semi-cylindrical wall portions 11c and 110! as best seen in FIGURE 5. In the illustrated embodiment, the impeller elements comprise gears having teeth such as 31a and 32:: extending axially of the gears and providing fluid receiving recesses therebetween for carrying fluid between the inlet chamber 24 and the outlet chamber 27 in a positive fashion. The

gears

31 and 32 may be mounted by means of

shafts

36 and 37, the shaft 36 being illustrated with a conventional driving tongue 36a for application of a driving force to gear 31 which in turn will drive gear 32. The portion 36b of shaft 36 within housing part 11 is journaled by means of a bearing sleeve 40 while the portion 360 of shaft 36 is journaled in housing part 12 by means of a bearing sleeve 41. Similarly shaft portions 37a and 37b for gear 32 are journaled *by means of bearing

sleeves

44 and 45. It will be understood that the drive gear 31 may be fastened to or integral with the shaft 36, while the driven gear 32 may be fastened to or integral with the shaft 37. As seen in FIGURE 2, shaft 36 enters through the front wall of housing part 11 through a seal 50.

As seen in FIGURES 2 and 3, a fixed side plate 50 is carried by the housing part 12 in lateral bearing relation to the

gears

31 and 32. The side plate 50, as seen in FIGURE 4, has apertures 50a and Sitb receiving

bearing sleeves

41 and 45 for shaft portions 360 and 37b. An aperture 52 in the side plate 50 communicates with discharge passage 26 in the housing part 12 as seen in FIG- URE 3, and the fixed plate 50 is provided with

slots

55 and 56 extending from the aperture 52 to provide communication between the aperture 52 and

passages

60 and 61 in the housing part 12. The

passage

60 and 61 lead to

chambers

64 and 65 communicating with the ends of shaft portions 360 and 3712. Since the

chambers

64 and 65 are thus referenced to the discharge side of the impeller means,

shafts

36 and 37 and therefore

gears

31 and 32 will be biased toward the right as seen in FIGURE 2 to tend to relieve lateral loading of the

gears

31 and 32 on the fixed side plate 59. As seen in FIGURE 2, sleeves 4i) and 44 may terminate in spaced relation to

gears

31 and 32 to leave clearance gaps 70 and 71 therebetween which allow for axial shifting of the

gears

31 and 32 to relieve lateral pressure on the fixed plate 50. A suitable fluid type seal between the housing part 11 and the fixed plate 50 is provided by means of an 0 ring 74 seated in a groove in the housing part 11 and completely surrounding the cavity 15.

For restricting leakage between the engaging faces of fixed plate 50 and

gears

31 and 32, a movable side plate is provided which is of single piece construction and of contour corresponding to the contour of the cavity 15 as illustrated in FIGURE 5, so that the outer marginal or peripheral edge of the movable side plate 86 conforms to the wall portions 11c, 11d, 11c and 11; as seen in FIGURE 6. Suflicient clearance is provided between the peripheral edge of the movable plate 80 and the wall portions llc-d-e-f to accommodate lateral movement of the movable plate 80 toward the

gears

31 and 32 to press the

gears

31 and 32 against the fixed plate 51 As seen in FIGURE 6, the movable plate 81 is provided with apertures 89a and 80b receiving bearing sleeves 4i! and 44 which thus serve to guide the lateral movement of the side plate 80. For preventing leakage between the discharge and inlet chambers indicated at 24 and 27 in FIGURE 5, a continuous elastic ring '90 is provided seated in a recess Siic of movable side plate 83 and bearing against the surfaces of the movable side plate defining the recess 80c and against the wall portions 11c, 11d, 11e, 11 and 11g of the housing part 11. The ring 90 is preferably compressed into the space between the wall portions just described between recess 80c and housing part 11 so as to urge the side plate 80 against the sides of

gears

31 and 32. The elastic ring 90 may be of any suitable cross sectional shape and may be made of any suitable elastic material.

It will be observed that a space is provided between the end face of side plate 80 and the side wall portion 11g of the housing part 11 which provides a bias chamber 100 for receiving fluid under pressure to bias the side plate 80 against the

gears

31 and 32. Passage 102 seen in FIGURE 6 extends through the movable side plate 80 and communicates with discharge chamber 27 as indicated in FIGURE at one end and with the bias chamber 100 at the other end to introduce discharge pressure into the bias chamber 100. A chamber 105 may be provided adjacent the end of shaft portion 37a and this chamber may be referenced to inlet pressure by means of

passages

108 and 109 seen in FIGURES 2 and 3.

It is to be understood that the sides of the

gears

31 and 32 are parallel to the cooperating faces of the fixed side plate 50 and movable side plate 80 and that the aforementioned surfaces are mutually perpendicular to the axes of

shafts

36 and 37 and to the wall portions llc-de-f of the cavity 15. The

bearings

40 and 41 and 44 and 45 are fixed relative to the housing parts. Fluid in chamber 100 is prevented from leaking through the peripheral clearance between side plate 80 and wall portions llc-d-e-f of cavity 15 into the region of lower pressure existing at inlet chamber 24 by the sealing action of the elastic ring 90. Leakage of fluid from chamber 100 through the clearances between bores 80a and 80b in plate 80, FIGURE 6, and the

bearings

40 and 44 is blocked off by the contact of plate 80 with the sides of the gears. The force exerted by the free or movable side plate 80 against the

gears

31 and 32 is transmitted by the gears to the fixed side plate 50. Thus both side plate 50 and side plate 80 contact with and press against the sides of

gears

31 and 32. This contact prevents leakage from the discharge chamber 27, FIGURE 5, to the inlet chamber 24 along the sides of the gears.

It will be observed that the pressure in chamber 65 is the pump discharge pressure while the pressure in chamber 105 on the opposite side of shaft 37 is the pump inlet pressure. These pressures acting on the ends of shaft 37 result in a force urging gear 32 against free side plate 80 and relaxing the load against fixed side plate 50. Similarly the pump discharge pressure acting on the end of shaft portion 360 in chamber 64 urges gear 31 against free side plate 80 and relaxes the load on fixed side plate 50. Therefore, by means of the pressure communication on the shaft ends, the contact load between fixed side plate 50 and the sides of the

gears

31 and 32 is less than the contact load between the free side plate 80 and the sides of the gears. This reduction in load permits the use of lower cost material for the fixed side plate 50.

Important features of novelty of the present invention reside in the shape of the free or movable side plate 80 as illustrated in FIGURES 2 and 6, the manner of piloting the free side plate by means of the

sleeves

40 and 44 and the one piece construction of the side plate together with the continuous seal ring of fixed cross-section as indicated at 90 in FIGURES 2 and 6 around the periphery of the movable side plate 80. The single piece construction of the movable side plate eliminates a serious leakage path which may occur at the point between two halves of a prior art type of free side plate. This will be apparent since some clearance must exist between the free side plate and the housing to permit movement of the plate and thus space may exist at the joint between the plate halves of a prior art side plate. At this point a leakage path would be created around the gear teeth at the point of meshing of the teeth, which leakage path is very short being only as long as one tooth width and hence may cause a leak of considerable magnitude. A pump utilizing the construction of the present invention has been found to perform with an internal leakage rate /3 as great as aircraft quality pumps constructed in accordance with the teachings of the prior art. A further important innovation in the construction of the present invention resides in the manner of pressure communicationwith the shaft ends, relieving the loading on the fixed side plate as previously described.

Summarizing the operation of the illustrated embodiment, the shaft 36 may be driven in any suitable manner to drive

gears

31 and 32 developing a substantial pressure difierential between inlet chamber 24 and outlet chamber 27. Sealing ring being under compression presses the movable side plate 80 against the gears to limit leakage while further loading of the side plate 80 is accomplished by referencing discharge pressure to the bias chamber by means of passage 102 indicated in FIGURE 6. Pressure on the fixed side plate 50 is less than the loading on the movable side plate 80 by virtue of the fact that

chambers

64 and 65, FIGURE 2, are referenced to discharge pressure while chamber 105 is referenced to inlet pressure by means of

passages

108 and 109 seen in FIGURES 2 and 3. The bearing

sleeves

40 and 44 serve to pilot lateral movement of the movable side plate which is pressed against the sides of

gears

31 and 32 to limit leakage.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

We claim as our invention:

1. A fluid pump comprising a housing having means comprising an interior wall defining an internal cavity and having inlet and outlet passages communicating with said cavity, rotary fluid impelling means rotatably disposed in said cavity for developing a pressure differential between inlet and outlet sides thereof communicating respectively with said inlet and outlet passages, a laterally movable side plate in said cavity on one side of and in lateral engagement with said impelling means and having clearance with respect to said interior wall of said cavity accommodating lateral movement of said side plate, means to apply lateral pressure to said side plate for movement towards one side of said impelling means, a fixed side plate at the opposite side of said impelling means for limiting lateral movement of said impelling means, and means comprising a pressure chamber for exerting a net lateral force on said impelling means tending to move said impelling means away from said fixed side plate to reduce the loading of said impelling means on said fixed side plate as compared with the loading of said movable side plate on said impelling means.

2. A fluid pump comprising a housing having an interior wall including opposite semi-cylindrical wall portions and opposite planar wall portions extending between respective margins of said semi-cylindrical wall portions and merging tangentially therewith, said interior wall defining a cavity, a pair of fluid impellers of gen erally circular configuration disposed in said cavity and having axes generally at the centers of curvature of the respective semi-cylindrical wall portions, means mountsaid impellers for rotation on their respective axes to establish a pressure differential between inlet and outoutlet chambers in said cavity disposed adjacent the respective planar wall portions, a laterally movable pressure plate disposed in said cavity in lateral engagement with said impellers and of contour generally conforming to the contour of said semi-cylindrical and planar wall portions and having clearance with respect thereto for movement laterally toward said impellers, a fixed plate bearing on said impellers on the opposite side thereof from said laterally movable pressure plate, means comprising a pressure chamber for exerting a net force on said impellers tending to move the impellers away from said fixed plate, and means referencing said pressure chamber to said outlet chamber to reduce the loading of said impellers on said fixed plate as compared with the loading of said movable pressure plate on said impellers, and means for urging said pressure plate laterally toward said impellers.

3. A fluid pump comprising a housing having an interior wall including opposite semi-cylindrical wall portions and opposite planar wall portions extending be tween respective margins of said semi-cylindrical wall portions and merging tangentially therewith, said interior wall defining a cavity, a pair of fluid impellers of generally circular configuration disposed in said cavity and having axes generally at the centers of curvature of the respective semi-cylindrical wall portions, means mountsaid impellers for rotation on their respective axes to establish a pressure dilferential between inlet and outlet chambers in said cavity disposed adjacent the respective planar wall portions, a laterally movable pressure plate disposed in said cavity in lateral engagement with said impellers and of contour generally conforming to the contour of said semi-cylindrical and planar wall portions and having clearance with respect thereto for movement laterally toward said impellers, a fixed plate bearing on said impellers on the opposite side thereof from said laterally movable pressure plate, means comprising a pressure chamber for exerting a net force on said impellers tending to move the impellers away from said fixed plate, and means referencing said pressure chamber to said outlet chamber to reduce the loading of said impellers on said fixed plate as compared with the loading of said movable pressure plate on said impellers, and means for urging said pressure plate laterally toward said impellers, said last mentioned urging means comprising a bias chamber for exerting a force on said pressure plate tending to move the pressure plate laterally against said impellers, and means referencing said bias chamber to said outlet chamber to bias said pressure plate toward said impellers.

4. A pump comprising a casing having a pumping chamber formed with an inlet and an outlet, a pair of gears including a driver gear and a driven gear meshing in said pumping chamber, said driver and driven gears each having a shaft portion on one side thereof formed with an end face spaced from an adjoining casing wall to form a chamber, movable end plate means engaging the other side of said driver and driven gears to seal the adjoining gear side faces, means to urge the movable end plate means towards the gears, and passage means communicating pump-generated pressure to said chambers to load said shaft portions axially in opposition to said end plate means with a net lateral force, thereby to control the thrust on the gear side faces.

5. A pump comprising a casing having a pumping chamber formed with an inlet and an outlet, a pair of gears including a driver gear and a driven gear meshing in said pumping chamber, said driver and driven gears each having a shaft portion on one side thereof formed with an end face spaced from an adjoining casing wall to form a chamber, fixed end plate means in said casing forming a thrust face on said one side of said driver and driven gears for engaging the adjoining gear side faces, movable end plate means engaging the other side of said driver and driven gears to seal the adjoining gear side faces, means to urge said movable end plate means toward the gears, and passage means communicating pump-generated pressure to said chambers to load said shaft portions axially in opposition to said end plate means with a net lateral force, thereby to control the thrust on the gear side faces and on said fixed end plate means.

6. In a gear pump having a housing including a pumping chamber formed with an inlet and an outlet and having meshed gears for driving fluid from the inlet to the outlet, a gear shaft having an end face spaced from an adjoining wall in said housing on one side of the gears, end plate means engaging the adjoining gear side faces on the opposite sides of the gears and having a motive surface formed thereon, and passage means conducting pump-generated pressure to said end face and to said motive surface for providing a net lateral force on the shaft in opposition to force on the end plate means, whereby the gears are sealed and the thrust on the gears is controlled.

7. A pump comprising a casing having a pumping chamber formed with an inlet and an outlet, rotary fluid displacement means comprising a shaft and an impeller on said shaft having radial side faces, a fixed sealing means on one side of said impeller and a movable sealing means on the opposite side of said impeller, one end of said shaft being spaced from an adjoining wall of said casing on said one side of said impeller to form a first chamber, said movable sealing means being spaced from an adjoining wall of said casing on the opposite side of said impeller to form a second chamber, and means form.- ing passages to supply fluid at pump-generated pressures to said first and second chambers for prow'ding a net lateral force on said shaft in opposition to the force on said movable sealing means to control the thrust on said fixed sealing means.

8. A pump comprising a casing having an inlet and an outlet and a generally ovaloidal pumping chamber formed therein including opposite semi-cylindrical ends joined by straight side walls, driver and driven meshing gears in said chamber rotatable on the axes of said semicylindrical ends and driving fluid from the inlet to the outlet, a generally ov aloidal end plate of conforming shape for said pumping chamber having a front face for sealing against the adjoining gear side faces and a rear face peripherally notched to receive an O ring seal cooperable with the casing, said rear face forming a mo tive surface inwardly of said notched portion, said motive surface being spaced from an adjoining casing wall to form a pressure chamber, said end plate having a pair of through openings formed therein, gear shafts for said gears extending through said through openings, and an end face on the end of each said gear shaft spaced from an adjoining casing wall on the side of said gears opposite from said end plate to form a pressure chamber, and means communicating pump-generated pressure to said pressure chamber for providing a net lateral force on the shaft in opposition to the force on the end plate to provide controlled pressure loading on the gears.

9. A pump as defined in claim 8, and said driven gear having a shaft portion formed with an end surface on the end opposite said end face, said end surface being spaced from an adjoining casing Wall to form a chamber, and means communicating said chamber to the pump inlet to keep the chamber vented of pressure fluid.

References Cited in the file of this patent UNITED STATES PATENTS 2,044,873 Beust June 23, 1936 2,676,548 Lauck Apr. 27, 1954 2,682,836 Orr July 6, 1954 2,707,441 Drennen May 3, 1955 2,718,758 Minshall et al Sept. 27, 1955 2,728,301 Lindberg Dec. 27, 1955 2,758,548 Rockwell Aug. 14, 1956 2,772,638 Nagely Dec. 4, 1956 2,809,592 Miller et al Oct. 15, 1957 2,824,522 Compton Feb. 25, 1958 2,824,524 Banker Feb. 25, 1958 2,932,254 Booth et al. Apr. 12, 1960 FOREIGN PATENTS 1,142,537 France Apr. 1, 1957