US3433164A

US3433164A - Motor-pump unit

Info

Publication number: US3433164A
Application number: US628205A
Authority: US
Inventors: Maynard J Neal
Original assignee: Buffalo Forge Co
Current assignee: BUFFALO FOREGE COMPANY
Priority date: 1967-03-03
Filing date: 1967-03-03
Publication date: 1969-03-18
Anticipated expiration: 1986-03-18

Description

March 18, 1969 M. J. NEAL MOTOR-PUMP mm Sheet of 2 Filed March 5, 1967 om F om/ /m io R NM: 9 i/ i: fi R H .2 @m. x MN mm N x Q m y INVENT OR MAYNARD J. NEAL March 18, 1969 M. J. NEAL 4 3,433,164

MOTOR-PUMP UNIT Filed March 5, 1967 INVENTOR MA Y/VA /?D J. NEAL W PM ATTORNEY United States Patent 3,433,164 MOTOR-PUMP UNIT Maynard J. Neal, North Tonawauda, N.Y., assiguor to Buffalo Forge Company, Buffalo, N.Y., a corporation of New York Filed Mar. 3, 1967, Ser. No. 628,205

US. Cl. 103-87 Claims Int. Cl. F04d 13/04, 1/14 ABSTRACT OF THE DISCLOSURE An hermetic motor-pump unit having contiguous motor and impeller housings and a common shaft mounting the motor rotor and impeller, with one end of the shaft being journalled in a bearing in the motor housing and the other end of the shaft being indirectly supported by a bearing mounted on the impeller housing which journals the impeller, with no bearing being located between the motor rotor and impeller. The impeller housing consists of a dished disc which is attached to the motor housing plate by means of fasteners.

Background of the invention The present invention relates to an improved hermetic motor-pump unit having an improved bearing and housing construction.

By way of background, an hermetic motor-pump unit includes contiguous motor and impeller housings, with a common shaft mounting a motor rotor and an impeller in axially spaced relationship. The motor rotor is located in the motor housing and the impeller is located in the impeller housing. In the past, the shaft was generally supported by two spaced bearings, the first being on the opposite side of the motor rotor from the impeller, and the second being located between the motor rotor and the impeller. This necessitated a relatively complex bearing supporting structure for the second hearing which was not only relatively costly, but also caused assembly and disassembly of the motor-pump unit to be a relatively complex procedure. In addition, the impeller was cantilevered relative to the second bearing and therefore there was a lever arm which magnified the radial force of the impeller and caused the second bearing to wear relatively quickly and therefore require relatively frequent replacement. In addition, pumps of the foregoing type required a seal proximate the impeller to prevent recirculation between the outlet and the inlet to the impeller. This seal usually permitted approximately two percent recirculation, which, in turn, lowered the efficiency of the pump. In addition, the impeller housings previously used were complex castings requiring intricate machining which rendered them costly and difiicult to manufacture. It is with an improved hermetic motor-pump unit which overcomes all of the foregoing shortcomings of the prior art that the present invention is concerned.

Summary of the invention It is accordingly one object of the present invention to provide an improved hermetic motor-pump unit having the supporting bearings mounted in such a manner so as to greatly reduce the radial loading thereon and thereby prolong bearing life.

Another object of the present invention is to provide a housing and bearing construction for an hermetic motorpump unit which permits simple initial assembly of the unit and simple subsequent disassembly and reassembly for bearing replacement and other repairs.

A further object of the present invention is to provide a highly simplified hermetic motor-pump unit in which recirculation at the impeller is eliminated thereby increas 3,433,164 Patented Mar. 18, 1969 ing efficiency of the pump. A related object of the present invention is to provide an improved bearing structure which also acts as a seal to prevent recirculation at the impeller during pump operation and which also includes provisions for automatic take-up for bearing wear.

Yet another object of the present invention is to provide an improved and highly simplified impeller housing construction consisting of a dished plate which is mounted on the motor housing by means of simple fasteners, such as bolts. Other objects and attendant advantages of the present invention will be readily perceived hereafter.

The improved hermetic motor-pump unit of the present invention includes a motor housing containing a stator which is isolated from the rotor by a stator liner. The motor rotor is mounted on a shaft which also mounts the impeller. A first bearing is supported by the motor housing and supports the end of the shaft which is remote from the impeller. A second bearing is mounted on the impeller housing and indirectly supports the other end of the shaft by supporting the impeller. There is no hearing or bearing supporting construction located between the impeller and the motor rotor. The configuration of the impeller bearing is such that it will automatically take up wear. In addition, the location of the impeller-supporting bearing obviates the cantilevered construction previously used when the bearing was between the motor rotor and the impeller, so that bearing life is prolonged because the bearing is subjected to less radial loading. The bearing at the impeller serves the additional function of a seal to cut down recirculation at the impeller, to thereby increase the efficiency of the pump. The highly simplified structure of the present invention eliminates the need for costly and complex bearing supporting structure which would otherwise be required between the motor rotor and impeller and which could form a source of pump malfunction or require periodic replacement. The impeller housing is highly simplified in that it constitutes a dished disc which is attached to the motor housing by simple fasteners, such as bolts. After the bolts are unfastened and the impeller housing removed, the shaft rotor-impeller assembly can be slid axially relative to the motor housing, and the bearings are exposed for ease of replacement. In short, the improved hermetic motor-pump unit of the present invention is highly simplified over that known in the prior art. The present invention will be more fully understood when the following portions of the specification are read in conjunction with the accompanying drawings wherein:

Brief description of the drawings FIGURE 1 is a side elevational view partially in cross section showing the improved hermetic motor-pump unit of the present invention;

FIGURE 2 is a view taken substantially along line 2-2 of FIGURE 1 and showing an end view of the improved impeller housing construction;

FIGURE 3 is a fragmentary view of an alternate hearing construction for supporting the end of the shaft remote from the impeller; and

FIGURE 4 is a view similar to FIGURE 2 but show-- ing a modified type of impeller housing.

Description of the preferred embodiments The improved hermetic motor-pump 10 of the present invention includes a motor housing 9 having a substantially cylindrical portion or shell 11 containing stator 12. The motor housing includes an end plate 13 extending transversely to cylindrical portion 11, plate 13 terminating in a cylindrical inturned portion 14 which supports a bearing cap 15 having a plug 16 therein. A second end plate 17, of substantially annular shape, is attached to shell 11 by means of bolts 18 having first ends secured to plate 17, as by welding, and having their central portions extending through bosses 19 formed integrally with shell 11, the fastening being completed by means of nuts 20 as shown. In FIGURE 1 there are three bosses 19 which are spaced 120 apart on housing 11. Any suitable number of bosses can be used. As can also be seen from FIGURE 1, there is a rabbet joint at 21 for firmly securing end plate 17 to shell 11. A cylindrical stator liner 22 has one end thereof secured to the outer peripheral edge of bearing cap 15 by welding at 23. The outer end of stator liner 22 extends through central aperture 24 in end plate 17, and is welded thereto at 25. It can thus be seen that stator liner 22 completely isolates stator 12 within housing 9. An electrical terminal box 11' is mounted on shell 11.

The motor-pump unit is also provided with a motor rotor 26 and an impeller 27, both mounted on common shaft 28. More specifically, the motor rotor 26 includes a rotor 26, and a cylindrical rotor cover 29 which is secured, as by welding, at its opposite ends to

rotor end plates

30 and 31 which have their inner edges secured to shaft 28 by welding. For pumping certain liquids, cover 29 and

end plates

30 and 31 may be omitted. Impeller 27 includes outer walls 32 and 33 having radial vanes 34 of any suitable configuration therebetween. Wall 32, at its inner end, terminates at annular inlet portion 35 which is coaxial with hub 36 formed at the center of plate 33. Hub 36 includes a central bore 37 which fits onto reduced end portion 38 of shaft 28, and the end 39 of hub 36 abuts the shoulder (not numbered) on shaft 28. It will be appreciated that end portion 38 need not be reduced. A roll pin or spring pin 40 extends through aligned bores 41 and 42 in hub 36 and through bores 43 and 44 in shaft 28 which is hollow and has a bore 28' therein extending throughout the length thereof. A hub cap 45 has a portion which fits within bore 28' of shaft 28 and also includes apertures which align with bores 41, 42, 43 and 44 so that roll pin 40 holds the shaft 28, hub 36 and hub cap 45 in assembled relationship. Hub cap 45 contains a plurality of radial bores 46 to conduct liquid radially outwardly which has previously flowed from left to right through bore 28 to thereby provide for circulation of liquid over rotor 29, as will become more apparent hereafter. Roll pin 40 is essentially a coil spring member which can adjust to different sized holes. This obviates the necessity for closely machining the bores 41-44.

The motor rotor-impeller-shaft assembly is supported within the motor-pump unit in an improved manner. More specifically, a frustoconical journal 47 having a cylindrical bore 48 therein is securely mounted on reduced end portion 49 of shaft 28 with the movement of journal 47 to the right being limited by shoulder 50. End portion 49 need not be reduced. Journal 47 fits within frustoconical bore 51 of bearing 52 which is mounted for axial sliding movement within cylindrical sleeve 53 having its left end firmly attached to bearing cap 15. A U- shaped retaining clip 54 has its legs extending into apertures 55 of sleeve 53 with its lower connecting portion located within keyway 56in bearing 52 to prevent the bearing from rotating with journal 47, while permitting it to move axially. A helical spring 57 is located between hearing 52 and bearing cap to urge bearing 52 and journal 47 into firm engagement. This relationship performs a plurality of functions. Firstly, it centers shaft 28 within stator liner 22, and furthermore, as wear of

bearings

52 and 58 and

journals

66 and 47 are experienced, the spring 57 will expand to cause bearing 52 and/or the motor rotor-impeller-shaft assembly to move to the right to take up such wear.

A combined bearing and seal 58 is provided for supporting and sealing at inlet 35 of impeller 27. More specifically, bearing 58 is securely mounted, as by pressing or gluing, within inlet conduit 59 secured as by welding to wall 74 of dished housing or casing 60. As can be seen from FIGURE 1, bearing 58 is annular and has outer cylindrical wall 61 and end wall 62 extending substantially perpendicularly thereto. These walls fit in abutting relationship with

walls

63 and 64, respectively, of inlet pipe 59. Bearing 58 also includes a frustoconical bore 65 which receives frustoconical surface 66 of impeller inlet 35 in complementary mating relationship. In addition, bearing 58 includes a substantially cylindrical bore 67, which is a continuation of frustoconical bore 66, bore 67, receiving cylindrical portion 68 of impeller inlet 32. The frustoconical bore 65, in conjunction with impeller portion 66 limits movement of shaft 28 to the right, considering that spring 57 urges the frustoconical surfaces of both bearings and the structure supported thereby into firm engagement. If for any reason whatsoever impeller 27 should move to the left in FIGURE 1 from the position shown so that surfaces 6566 move out of engagement, the shaft 28 will remain centered within liner 22 because the cylindrical surfaces 6768 will remain in engagement to provide the centering action. It is to be especially noted that by locating the bearing on the outside of the impeller,

rather than on a portion of the shaft extending through the impeller, there is no obstruction to flow into inlet 35, thereby enhancing suction flow conditions.

It can be seen that bearing 58 is located to the right of the line of radial thrust provided by impeller 27. This can be appreciated more readily when it is considered that in previous constructions the hearing was located between impeller 27 and motor rotor end plate 31. In the latter orientation there was a lever arm between the supporting bearing and the line of radial thrust produced by impeller 27 which magnified the force on the hearing and therefore accelerated its wear. The location of bearing 58 virtually eliminates the foregoing characteristic of prior constructions. Since the amount of radial thrust on the bearing 58 is reduced, its life is prolonged. In addition, it can be seen that the structure for mounting bearing 58 is highly simplified especially when it is considered that in the past a relatively complex construction was required to mount a bearing between impeller 27 and motor rotor 26, such construction being subjected to malfunction, clogging and the like and also impeding the disassembly of the pump for repair or replacement of parts. As will become more apparent hereafter, the present pump can be disassembled in an extremely simple and rapid manner to replace parts or effect repair as required.

The pump portion of the improved motor-pump unit includes annular inlet portion 59 which has a dished housing member 60 welded thereto at 61. The outer edge of casing 60 remote from weld 61' is formed into a rim portion 62 which is received in a rabbet relationship relative to the outer edge portion 63 of motor housing end plate 17. An annular gasket '64 is located between rim 62 and the face 65 of end plate 17 to prevent leakage therebetween. As can be seen from FIGURES 1 and 2, housing 60 is held in assembled relationship relative to plate 17 by a plurality of washers 66 which bear against surface 67 of rim 62, said Washers being held tightly against portion 67 by nut-bolt assemblies 68 which extend through bores 69 in plate 17. Bores 69 need not be accurately machined to a close tolerance, as the rabbet joint locates the housing 60.

Dished housing can be made by a stamping, spinning or pressing process and therefore is not as costly as cast constructions used in the past. Housing 60 does not require extensive machining. Furthermore, the outer edge 70 of rim 62 is located relative to plate 17 by shoulder 71 on said plate to thereby effect alignment of housing 60 relative to the motor housing. The nut-bolt assemblies 68 merely tighten housing 60 in its proper position. The outlet from housing 60 constitues a simple conduit 72 which has its lower portion welded as at 73' to the outside of the housing and/or at 73" to the inside of the housing 60 to provide tangential discharge. A plurality of reinforcing gussets 73 extend between inlet conduit 59 and wall 74 of housing 60 to provide the desired stability to conduit 59 for properly supporting bearing 58. Gussets 73 also rigidize housing 60 to permit the entire unit to be supported at housing 60, as by the conduits leading thereto.

The embodiment shown in FIGURE 4 is identical in all respects to that shown in FIGURE 2 except that the outlet conduit 74' is located in such a position relative to housing 60 to provide a centerline discharge, conduit 74 being welded to the outside of housing 60 at 75 and/or at 75' to the inside of housing 60. In all other respects, the impeller housing of FIGURE 4 is identical to that shown in FIGURES 1 and 2.

In operation, liquid is pumped into the bore 76 of conduit 59 and then through the central inlet portion 35 of impeller 27 from which it is directed centrifugally outwardly by vanes 34 between impeller Walls 32 and 33 and then out of discharge conduit 72. As can readily be appreciated, bearing 58 supports impeller 27 for rotation and also provides the necessary sealing to prevent recirculation between the inside 77 of housing 60 and inlet 76 of conduit 59. A small portion of the liquid will pass from chamber 77 in impeller housing 60 to chamber 78 to the right of rotor plate 31, through the space 79 between the stator liner 22 and the rotor cover 29, to effect cooling of the motor rotor and to provide an axial balancing force, and then to the space 80 to the left of rotor end plate 30. A portion of the liquid will pass between journal 47 and surface 51 of bearing 52 to provide lubrication and a portion of the liquid will also pass through kcyway 56 and holes 55 in bearing 52 into chamber 81 which houses spring 67. The liquid will thereafter enter the bore 28 of hollow shaft 28 and pass to the right until it is ejected from radial apertures 46 in hub cap 45. Essentially therefore, hub cap 45 aids in providing a pumping effect which causes a portion of the liquid being pumped to be passed across the rotor and the bearing 52 for cooling and lubrication and axial thrust balancing purposes. In addition, a portion of the liquid being pumped will be forced between surfaces 65 and 66 at bearing 58 for the purpose of providing lubrication and cooling in this area. As an alternative to the circulation through shaft bore 28', plug 16 may be removed from plate and a conduit inserted to conduct the liquid to any desired suitable location. This alternative permits a solid shaft to be used.

An alternate bearing construction is shown in FIG- URE 3. The bearing 83 is cylindrical rather than conical as shown at 52 in FIGURE 1. As can be seen from FIGURE 3, shaft 28 includes an end portion 49. The bore of bearing 83 fits on reduced end portion 49 and the outer edge of bearing 83 includes a keyway 84 which receives the base of pin 54, the legs of which are located in openings 55 of sleeve 53 which is secured to bearing cap 15. At this point it is to be noted that all elements having the same numerals as shown in FIG- URE l constitute structure which is identical to that shown in FIGURE 1 and therefore a detailed description of the mode of operation of these elements of structure will be omitted at this point in the interest of brevity. Bearing 83 includes a conduit 85 therein for permitting liquid to pass from chamber 80 to chamber 81 from which it passes into bore 28' of shaft 28. From a view of FIGURE 1 it can be seen that a low pressure area of the pump is to the right of impeller 27, that is Within conduit 59. This will automatically cause the shaft 28 to travel to the right when it is in operation, thus eliminating the need for a spring such as shown at 57 in FIGURE 1. This permits a cylindrical bearing 83 to be used in the embodiment of FIGURE 3 to replace the conical bearing 52 of FIGURE 1, thereby reducing the expense or cost of the construction inasmuch as the use of a cylindrical hearing such as 83 obviates the necessity for a conical bearing 52, journal 47 and spring 57. In addition, the elimination of spring 57 prolongs the life of bearing 58 because the axial force of said spring on hearing 58 is then eliminated. It is to be noted, however, that bearing 58 at impeller 27 must have cylindrical surfaces 67-68 because when the motor-pump is not in operation, shaft 28 may move to the left inasmuch as there is no biasing force in chamber 81 tending to move it to the right. However, in the event that it does move to the left, rotor 26 will maintain its concentricity relative to the stator liner 22 inasmuch as surfaces 67-68 of the impeller-bearing will remain in engagement notwithstanding the fact that frustoconical surfaces 65-66 may have moved out of engagement, as shaft 28 moves to the left.

It is to be noted that there are facing vertical faces of bearing 58 and wall 32 of impeller 27. These faces normally have a space 76 therebetween, as shown in FIGURE 1. If there should be excessive wear of bearing surface 65, these faces will come into engagement to slow further wear of bearing surface 65. If disassembly of the motor-pump 9 is required, it is merely necessary to unfasten nut-bolt assemblies 68, move housing 60 to the right or shell 11 to the left in the event housing 60 is attached permanently to a conduit, and pull the impeller-rotor-shaft assembly from shell 11. Reassembly is effected by a reverse sequence of steps. The foregoing disassembly may be required for periodic replacement of

bearings

52 or 58, or other reasons. It is to be especially noted that there is no bearing supporting structure between impeller 27 and motor rotor 26 which could impede the simple disassembly and subsequent assembly. Bearing 52 is removed by a simple axial sliding movement relative to sleeve 53. It is replaced by a reverse movement. Bearing 58 is removed by pulling it out of conduit 59.

It can thus be seen that the improved motor-pump unit 9 of the present invention is manifestly capable of achieving the above enumerated objects and while preferred embodiments of the present invention have been disclosed, it will be understood that it is not limited thereto but may be otherwise embodied within the scope of the following claims.

I claim:

1. A motor-pump unit comprising a motor housing having first and second ends, an impeller housing located proximate said second end of said motor housing, a motor rotor, an impeller, a rotatable shaft having first and second ends for mounting said motor rotor and said impeller in axially spaced relationship with said motor rotor being located in said motor housing and said impeller being located in said impeller housing, first bearing means mounted proximate said first end of said motor housing and mounted on the outside of said shaft for rotatably supporting said first end of said shaft, and second bearing means having an outer surface mounted in sealing engagement with the inside surface of said impeller housing and having an inner surface in engagement with the outer surface of said impeller for rotatably supporting said second end of said shaft and providing a seal between said impeller and said impeller housing, said first and second bearing means constituting the sole support for said shaft and said impeller to provide an unobstructed space therebetween.

2. A motor-pump unit as set forth in claim 1 wherein said impeller comprises conduit means formed by an inner surface spaced from said outer surface of said impeller for providing a central unobstructed annular inlet portion, a plurality of vanes outwardly disposed relative to said conduit means, said first bearing means including a conical opening with its larger portion facing said second bearing means, said second bearing means including a conical opening with its larger portion facing said first bearing means, said outer surafce of said second bearing means including a portion extending transversely to the longitudinal axis of said shaft with said portion being in liquid tight engagement with said impeller housing to prevent liquid flow therebetween to provide said seal, and spring means biasing said first bearing means toward said second bearing means to take up wear between said shaft and said first bearing means and between said impeller and said second bearing means and also maintain a tight sealing relationship between said outer surface portion of said second bearing means and said impeller housing.

3. A motor-pump unit as set forth in claim 2 wherein said second bearing means includes a surface which extends transversely relative to the longitudinal axis of said shaft and which faces said impeller, and an external surface on said impeller facing said surface of said second bearing means and spaced therefrom for engaging said second surface only if excess Wear is experienced between said second bearing means and said shaft.

4. A motor-pump unit as set forth in claim 2 wherein said impeller housing comprises an annular end plate with a central aperture therein, a first rabbet joint between said annular end plate and said motor housing, boss means on said motor housing proximate said annular end plate, first bolt means extending through said boss means and attached to said annular end plate for holding said annular end plate in assembled relationship with said motor housing, a dished impeller housing portion, a second rabbet joint between said annular end plate and said dished impeller housing portion, seal means proximate said second rabbet joint, second bolt means extending through said annular end plate, and washer means on said second bolt means in engagement with both said dished impeller housing portion and said annular end plate to secure said annular end plate and said dished impeller housing portion in assembled relationship.

5. A motor-pump unit as set forth in claim 2 wherein said second bearing means includes a conical portion for carrying the load of the impeller and a cylindrical portion for centering said shaft when said conical portion is not engaged by said impeller.

6. A motor-pump unit as set forth in claim 5 wherein said first bearing means is a sleeve-type of bearing, and wherein said impeller means includes a cylindrical portion and a conical portion, and hydraulic circuit means forming a part of said motor-pump unit for exerting an hydraulic pressure for maintaining said conical portion of said impeller in engagement with said conical portion of said second bearing means during motor-pump operation, said cylindrical portion of said second bearing means maintaining said rotor centered in said stator liner by continued engagement with said cylindrical portion of said impeller in the event said conical portions of the bearing and said impeller move out of engagement.

7. A motor-pump unit as set forth in claim 2 wherein said impeller housing comprises an end plate mounted on said motor housing, a dished plate located proximate said 8 cndplate with said impeller located therebetween, and fastener means for afiixing said dished plate on said end plate.

8. A motor-pump unit as set forth in claim 1 wherein said impeller housing comprises an annular end plate with a central aperture therein, a first rabbet joint between said annular end plate and said motor housing, boss means on said motor housing proximate said annular end plate, first bolt means extending through said boss means and attached to said annular end plate for holding said annular end plate in assembled relationship with said motor housing, a dished impeller housing portion, a second rabbet joint between said annular end plate and said dished impeller housing portion, seal means proximate said second rabbet joint, second bolt means extending through said annular end plate, and washer means on said second bolt means in engagement with both said dished impeller housing portion and said annular end plate to secure said annular end plate and said dished impeller housing portion in assembled relationship, said second bearing means being mounted on said dished impeller housing portion.

9. A motor-pump unit as set forth in claim 8 including a stator liner having first and second ends in said motor housing, means affixing said first end of said stator liner proximate said first end of said motor housing, said second end of said stator liner being of approximately the same diameter as said central aperture in said annular end plate, and a weld securing said second end of said stator liner in said annular aperture.

10. A motor-pump unit as set forth in claim 1 wherein said second bearing means is conical and wherein said outer surface of said second bearing means includes a portion extending transversely to the longitudinal axis of said shaft for engaging an adjacent portion of said impeller housing, and spring means for biasing said first bearing means toward said second bearing means to take up wear between said second bearing means and said shaft and also maintain a tight sealing relationship between said outer surface-of said second bearing means and said adjacent portion of said impeller housing.

References Cited UNITED STATES PATENTS 2,741,990 4/1956 White 103-87 2,796,835 6/1957 White 10387 3,114,323 12/1963 Moser 10387 3,162,128 12/1964 Horlen 1O387 3,188,966 6/1965 Tetlow 103l03 3,195,466 7/1965 Young 1O387 ROBERT M. WALKER, Primary Examiner.

US. Cl. X.R. 103103