US3115841A

US3115841A - Pump assembly

Info

Publication number: US3115841A
Application number: US152838A
Authority: US
Inventors: Robert R Tilson
Original assignee: Thompson Ramo Wooldridge Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1961-11-16
Filing date: 1961-11-16
Publication date: 1963-12-31
Anticipated expiration: 1980-12-31

Description

Dec. 31, 1963 Filed NOV. 16, 1961 R. R. TILSON 3,115,841

PUMP ASSEMBLY 2 Sheets-Sheet 1 INVENTOR. @oaaer 2 7/260 A 'ITORNIEYS Dec. 31, 1963 Filed Nov. 16, 1961 R. R. TILSON 3,115,841

PUMP ASSEMBLY 2 SheetsSheet 2 INVENTOR. 0aer4 72250/1 A TTORNE YS United States Patent 3,115,841 PUMP ASSEMBLY Robert R. Tilson, Cleveland, Ohio, assignor to Thompson Rama Wooldridge Inc Cleveland, Ohio, a corporation of Ohio Filed Nov. 16, 1961, Ser. No. 152,338 '7 Claims. (Cl. 103-87) This invention relates generally to pumping apparatus and more particularly relates to a high speed, low pressure fuel transfer pump of high delivery capacity wherein the pump and its driving motor are disposed in collapsed or nested assembly to reduce the axial length of the unit, which nesting arrangement is accomplished by utilizing a hollow conical impeller wherein a bearing assembly is accommodated within the central portion of the impeller, the bearing suspension including annular contact bearings which are spring-loaded and the impeller forming with the pump casing a circumferential orifice to throttle pump volute leakage behind the impeller and past the bearing suspension.

It is an object of the present invention to provide a collapsed or nested assembly of a pump and motor which reduces the axial length of the pumping unit.

Another object of the present invention is to provide a centrifugal pump utilizing vent holes for relieving pressure behind the impeller so that leaked in volute pressure will not add to the forward thrust of the impeller under load.

A still further object of the present invention is to provide a nested pump and motor assembly utilizing a hollow conical impeller wherein the bearing assembly is accommodated in the central portion of the impeller and wherein dirt drain holes in the bottom of the bearing chamber are vented back to pump inlet, thereby effecting removal of dirt particles from behind the impeller which hamper pump operation and deteriorate bearing life.

Another object of the present invention is to provide in a centrifugal pump a bearing suspension consisting of faceto-face mounted angular contact bearings spring-loaded and nested with a hollow conical impeller to reduce the overall axial length of a combined pump and motor unit.

Another object of the present invention is to provide a hollow conical impeller and a pump casing providing a volute pumping chamber wherein a circumferential orifice throttles pump volute leakage behind the impeller to a zone of lower pressure.

A still further object of the present invention is to provide a hollow conical impeller for a pump with screw vanes wherein a bearing assembly is accommodated in the hollow central portion of the impeller.

Many other features, advantages and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description which follows and the accompanying sheets of drawings in which a preferred structural embodiment of a pump incorporating the principles of the present invention is shown by way of illustrative example.

On the drawings:

FIGURE 1 is a cross-sectional view with parts in elevation showing a combined pump and motor unit in accordance with the principles of the present invention;

IGURE 2 is a bottom plan view of the pump of FIG- URE 1;

FIGURE 3 is a fragmentary cross-sectional view taken generally on line IIIHI of FIGURE 1;

FIGURE 4 is a fragmentary insert showing an alterna- 3,ll5,8il Patented Dec. 31, 1963 "ice tive form of circumferential orifice for the pump of FIG- URE 1; and

FIGURE 5 is a view similar to FIGURE 4 but showing an alternative construction of circumferential orifice.

As shown on the drawings:

The combined pump and motor unit of the present invention is shown generally at 10. Although the pump apparatus ill is of general utility, it functions particularly well as a high speed, low pressure fuel transfer pump of very high delivery capacity. It will be appreciated, of course, that the pump it can also serve as a booster and vapor separator, or may be utilized effectively in other organizations and environments.

In the exemplary illustration herein disclosed, it is contemplated the pump will be disposed uprightly for operation with the impeller and motor rotatable on a vertical axis. In this connection, the impeller is particularly characterized by a center hub 11 having upstanding walls 12 which extend generally radially outwardly and axially away from the hub 11, the walls 12 being disposed to form a hollow conical configuration including an interior cavity 14 surrounded by an outer rim 16. The hub 11 forms a bottom wall 17 for the cavity'14. The hub 11 is also formed with an opening 18 counterbored as at 19.

On the outer peripheral surface of the impeller there is formed screw vanes 20 which operate to advance fluid axially upon rotation of the impeller about its axis.

The casing for the pump and motor unit is divided into several sections and it will be noted there is provided, first of all, an impeller housing shown at 21 and including a bottom Wall 22 having a plurality of upstanding bosses 23, herein shown as three in number spaced circumferentially from one another. Each boss is formed with a through opening 24 by means of which the pump and motor combination may be mountedly attached in an operating environment.

The formation of the bosses 23 also affords the attachment of a corresponding plurality of fasteners 26 which are used to connect a screen assembly 27 to a radially outwardly projecting portion 28 of the impeller housing 21, thereby to form a screened inlet 36 for the pump through which the fluid to be pressurized by the pump is directed.

The impeller housing 21 includes an upstanding wall 31 spaced concentrically outwardly of the impeller axis and having an inner surface disposed in close running relationship with the outer peripheral edge of the screw vanes 26) on the impeller. The impeller housing 21 is flanged as at 32 thereby to accommodate a plurality of fasteners 33 facilitating connection of the impeller housing 21 to a second casing part, herein referred to as a volute housing 33. The volute housing 33 is also flanged as at 34 and a gasket 36 may be interposed between the

flanges

32 and 34 so that tightening the fasteners 33 will provide a closed sealed joint between the impeller housing 21 and the volute housing 33.

The volute housing 33 has a volute 37 formed therein and further includes an inner wall 38 which extends generally vertically downwardly and merges with an inner wall portion shown at 39 which extends radially inwardly and axially downwardly, terminating in an end wall 49.

There is thus formed by the

inner wall portions

38, 39 and 4%) a cavity 41 which is disposed concentrically inwardly of the cavity 14 in the impeller.

Any suitable form of driving means may be provided for the pump, however, in accordance with the exemplary disclosure herein set forth there is provided a hydraulic motor shown generally at 42. A motor adapter is shown 3 at 43 and includes a flange 44 apertured as at 46 to pass a plurality of fasteners 47. The inner wall 3 has a radial portion formed with suitably threaded openings Ell receiving the fasteners 47, by means of which the hydraulic motor 4-2 may be placed in firm assembly with the pump casing.

The motor 42 has a power take-elf shaft 51 connected as at 52 to a bushing 53. The bushing 53 is flanged as at 54 and carries a bearing spacer 56 intermediate the axial length thereof, thereby to confine a bearing suspension between the flange 54 and a thrust washer shown at 57. interposed between the thrust washer 57 and the wall 17 is one or more impeller shims S3.

The bearing suspension further includes an outer housing 59 flanged as at 69 and Within the housing 59 there is contained two face-to-face mounted angular contact ball bearings shown generally at 61 and 62. The ball bearings are spring-loaded by a preloading spring 63 bottomed against the outer race of the ball bearing 62 and engaged against the motor adapter 43. It will be noted the bearing assembly is mounted in the cavity 41 provided by the inner wall of the volute housing or casing which is, in turn, within the cavity 14 of the impeller. Thus, a large part of the motor or driving means of the pump is surrounded by the volute pumping chamber and the nested relationship of the pump casing, the pump impeller and the pump motor provides an arrangeent characterized by an unusually small axial length.

The volute housing 33 is formed with an outlet 66 which extends through a mounting pad 67 to facilitate attachment to a suitable conduit for directing the discharge of the pump to a point of utilization.

The impeller is connected to the power take-off shaft by means of a shaft member shown at 70 which extends through the opening 18. A key 71 locks the hub 11 in corotatable assembly with the shaft 70 and the end of the shaft '79 accommodates a fastening nut 72. A washer 73 is received within the counterbore l9 and shoulders against the bottom of the counterbore 19 so that tightening of the nut 72 will fasten the hub 11 in firm assembly with the shaft 70.

The inner wall 39 of the casing is relieved as at 80, thereby to form an annular recess between the Walls 12 of the impeller and. the volute housing 33. At the area confronting the rim 16 of the impeller, however, and at the area immediately inwardly thereof, there is formed on the

inner wall

38, 39, a generally horizontal surface 81 and a surface 82 which extends axially downwardly and radially inwardly. There is thus formed between the

wall portions

81, 82 and the

wall portions

14, 16, a circumferential orifice 83 which is provided to throttle pump volute leakage to a lower pressure behind the impeller. This leakage flow is then bled from the recess 89 through one or more vent openings or bleed holes 84 which intersect the

end wall

39, 46, thereby preventing discharge pressure from building up behind the impeller. That arrangement reduces the thrust force acting on the impeller and the holes 84 also provide a moving fluid across the bearing assembly 61, 62 so that a fresh supply of pumping medium is provided for lubricating and cooling the bearing surfaces.

If desired, the circumferential orifice 83 could be formed in other configurations. For example in FIG- URE 4, a circumferential orifice 83a is shown formed between a horizontal surface 81a and a vertical surface 8211 provided on the volute casing 38a. In this form of the invention the impeller has a rim 16a which extends horizontally and an inner wall surface which extends vertically as at Ma. Thus, pump volute leakage is throttled through the orifice 83a to a recess 80a constituting a zone at lower pressure.

In FIGURE 5, an orifice is shown at 83b which is formed by a horizontal surface 81b formed on the volute housing 38b and confronting a rim 16b formed on the wall 12b of the impeller, thereby to throttle pump volute 4 leakage into a recessed area inwardly of the orifice 83b and shown generally at 8%.

In order to effect the removal of dirt particles from behind the impeller which hamper pump operation and deteriorate bearing life, the hub 11 is formed with a plurality of vent openings 90 which extend axially, intersecting the wall 17 and communicating with the inlet portions of the impeller housing 21. Thus, dirt drained through the openings 9i) is vented back to the pump inlet. The bottom wall 22 of the impeller housing 21 has an upwardly dished portion which terminates in a center boss 91 recessed as at 92 to provide clearance for the end of the shaft 70. Accordingly, fluid passing through the inlet screen assembly 27 is guided and directed through inlet passages 93, whereupon the fluid is swept and impelled upwardly by the vanes 20 through the pumping chamber formed between the inner and outer casing walls and directed into the volute 37 for discharge through the outlet 66. The impeller casing has a plurality of vapor elimination holes 94 formed therein which are tangential and which assist in vapor elimination in the event it is desired to use the pump as a booster and vapor separator.

Although minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention: 1. A pump housing comprising an upstanding inner wall disposed concentrically outwardly of a vertically disposed pump center line axis to form a cavity and terminating in an end wall to close the bottom of the cavity, an outer wall means forming with said inner wall a volute pumping chamber having an inlet and an outlet, a motor nested in said cavity having a power takeoff shaft extending through said end wall into said pumping chamber, a rotatable impeller having a hub, annular pumping vanes and a centrally disposed cavity to fit in nested assembly in said pumping chamber and having a driven connection with said shaft, said hub having at least one drain hole extending therethrough to drain dirt from the bottom of said cavity, and a bearing susension in said housing cavity for journaling said motor shaft comprising two spring-loaded face-to-face mounted angular contact bearings, whereby said shaft is journaled without increasing the axial length of the pump and motor combination, said impeller annular wall and said housing inner wall together with one another forming a circumferential orifice communicating with the volute to throttle pump volute leakage to a zone at lower pressure behind said impeller, said housing having holes intersecting said inner wall to bleed off the leakage flow, thereby preventing pressure build-up behind the impeller and insuring fluid circulation to cool and lubricate the bearing suspension.

2. A pump comprising a housing having a volute formed therein and including an inner wall which extends axially and merges with an inner wall portion which extends radially inwardly and extends axially to terminate in an end wall, thereby forming a cavity inwardly of said volute,

bearing means in said cavit an impeller journaled in said bearing means and having a vaned annular wall rotatable in said pumping chamher,

said impeller annular wall and said housing inner wall together with one another forming a circumferential orifice communicating with the volute to throttle pump volute leakage against said bearing means, thereby to cool and lubricate the bearing means,

said inner housing wall having openings formed therein to bleed olf the leakage flow, thereby preventing pressure buildup behind the impeller.

3. A pump as defined in claim 2, said circumferential orifice being formed by two confronting radial surfaces between said impeller and said housing.

4. A pump as defined in claim 2, said circumferential orifice being formed by two confronting surfaces extending radially and axially between said impeller and said housing.

5. A pump as defined in claim 2 and a motor nested in said cavity with said bearing means and connected to said impeller, thereby to provide a pumping motor combination of reduced axial length.

6. A pump as defined in claim 2, said bearing means comprising two spring loaded face-to-face mounted angular contact bearings.

7. A pump as defined in claim 2, said impeller having a hub portion spaced axially adjacent said end wall of said housing and being formed with vent openings which extend axially therethrough for efiecting removal of dirt particles from behind the impeller.

References Cited in the file of this patent UNITED STATES PATENTS 1,610,454 Lawaczeck Dec. 14, 1926 2,715,367 Kodet et al Aug. 16, 1955" 2,777,395 Disbrow Jan. 15, 1957 2,846,952 Ridland Aug. 12, 1958 2,868,133 Clark Jan. 13, 1959 2,936,714 Balje May 17, 1960 FOREIGN PATENTS 971,935 France Oct. 23, 1950

Claims

1. A PUMP HOUSING COMPRISING AN UPSTANDING INNER WALL DISPOSED CONCENTRICALLY OUTWARDLY OF A VERTICALLY DISPOSED PUMP CENTER LINE AXIS TO FORM A CAVITY AND TERMINATING IN AN END WALL TO CLOSE THE BOTTOM OF THE CAVITY, AN OUTER WALL MEANS FORMING WITH SAID INNER WALL A VOLUTE PUMPING CHAMBER HAVING AN INLET AND AN OUTLET, A MOTOR NESTED IN SAID CAVITY HAVING A POWER TAKEOFF SHAFT EXTENDING THROUGH SAID END WALL INTO SAID PUMPING CHAMBER, A ROTATABLE IMPELLER HAVING A HUB, ANNULAR PUMPING VANES AND A CENTRALLY DISPOSED CAVITY TO FIT IN NESTED ASSEMBLY IN SAID PUMPING CHAMBER AND HAVING A DRIVEN CONNECTION WITH SAID SHAFT, SAID HUB HAVING AT LEAST ONE DRAIN HOLE EXTENDING THERETHROUGH TO DRAIN DIRT FROM THE BOTTOM OF SAID CAVITY, AND A BEARING SUSPENSION IN SAID HOUSING CAVITY FOR JOURNALING SAID MOTOR SHAFT COMPRISING TWO SPRING-LOADED FACE-TO-FACE MOUNTED ANGULAR CONTACT BEARINGS, WHEREBY SAID SHAFT IS JOURNALED WITHOUT INCREASING THE AXIAL LENGTH OF THE PUMP AND