US2993449A - Motor-pump - Google Patents

Description

July 25, 1961 R. F. HARLAND 2,993,449

MOTOR-PUMP Filed March 9, 1959 2 Sheets-Sheet 1 INVENTOR. RAYMOND HARLAND July 25, 1961 R. F. HARLAND MOTOR-PUMP 2 Sheets-Sheet 2 Filed March 9, 1959 INVENTOR. RAYMOND F. HARLAND mun-"mum 5 United States Patent 2,993,449 MOTOR-PUMP Raymond F. Harland, Southington, Conn., assignor t0 Hydratomic Engineering Corporation, a corporation of Connecticut Filed Mar. 9, 1959, Ser. No. 798,055 6 Claims. (Cl. 103-87) My invention relates to fluid pumping apparatus, and particularly to pumping apparatus of the type comprising a unitary electric motor and pump.

Unitary motor-pumps which have found use in industry heretofore have been of one of two types. One such type includes a combination armature and impeller, whereby the impelled liquid flows through the entire motor-pump. The other type comprises a motor of essentially conventional construction, and a centrifugal pump also of essentially conventional construction, mounted on one end of the motor housing. Fluid flow is in and out of the pump section, with a feedback or auxiliary path through the motor for cooling purposes.

Each of these types of motor-pumps suffers from certain disadvantages. While the first type has the advantage of bringing the main fluid flow through the motor portion to cool the motor and the bearings, it has the disadvantage of incorporating an impeller which is not of the high pressure type, and which is also an integral part of the motor and not capable of ready removal or change.

Similarly, while the second type of motor-pump has the advantage of high pressure centrifugal impeller, and may provide for accessibility for replacement and change of impeller, it has the disadvantage that full fluid flow does not pass through the motor and the bearings.

In addition, pumps presently in use which are suitable for use in pumping corrosive liquids, utilize a partition or isolating sheath or liner of suitable compatible or nonreactive metal between the motor stator portion and the fluid path. In pumps where there is fluid flow around the motor rotor, this means that such liner must be in the air gap of the motor. This detracts from the efficiency of the motor by requiring a larger air gap and also by reason of induced currents in the liner. The presence of such a liner also limits the usefulness of the pump in applications where the pressure of the system is high, since the liner is subject to distortion by high pressures.

It is an object of the present invention to provide a combination motor and pump including a high pressure centrifugal type impeller which is accessible for replacement or change and in which the main fluid flow is through the motor and the motor bearings.

It is another object of the invention to provide a combination motor and pump in which the main portion of fluid flow passes through the motor and over the bearings and in which a portion thereof also passes into contact with the stator portion of the motor and through the air gap between the rotor and stator. p It is another object of the invention to provide a motorpump which is suitable for use in pumping corrosive chemicals, Whichhas high efficiency and which is also able to pump such chemicals under high pressure.

Other objects and advantages of the invention will in part become obvious and in part be pointed out in the following detailed description, and its scope will be pointed out in the appended claims.

In accordance with the invention, a motor-pump is pro vided having a main housing and intake and outlet housing end members supported on each end of the housing and each having a centrally located bearing portion surrounded by "fluid passages. A stator assembly is fixedly supported in the housing and a rot-or assembly is provided including a shaft rotatabl'y supported between the bearing portions and including a rotor carrier having fluid pas- 2,993,449 Patented July 25, 1961 "ice sages corresponding to those of the housing end members. The rotor shaft is extended through the outlet bearing portion and a centrifugal type fluid impeller is supported on the extension. Impeller housing means is also provided enclosing the impeller and removably mounted on the main housing.

In the drawings:

FIGURE 1 is a longitudinal sectional View of a motorpump constructed in accordance with the invention;

FIGURE 2 is an exploded view of the pump of FIG- URE 1;

FIGURE 3 is a view of a modification of the invention;

FIGURE 4 is a view of another modification of the invention.

The invention is shown in the drawings as incorporated in a motor-pump comprising a cylindrical main housing member 10, having open ends and having a motor stator assembly therein including windings 11 and a laminated core structure 12 of conventional motor type construction. The motor stator assembly, including the windings 11 and the laminations 12, are preferably impregnated with and embedded in an epoxy type plastic resin compound 11A, to provide a solid torroidal shaped body, the whole being cast in place in the housing 10. The internal surface 13 or bore of the embedded assembly is machined to accurate concentricity about the center line of the housing 10, and openings are left for housing clamping bolts 32.

For the purpose of supporting a rotor assembly to be described, a pair of combination bearing supports and housing end members are provided, comprising an intake housing end member 14 and an outlet housing end member 15.

The intake housing end member 14 is generally circular, conforming to the end of the main housing 10, and has a centrally located axially elongated hub portion 16 apertured to provide a plurality of fluid passages 17. A central, cylindrical bearing portion 16 supports an insert or sleeve 18 of suitable bearing material such as self-lubricating carbon graphite.

The outlet housing end member 15 is also generally circular, and has a centrally located axially elongated hub and bearing portion 19, 19, fluid passages 20, and a bearing sleeve 21.

In order to seal the inner chamber in a fluid-tight manner, resilient sealing members 28 and 29 are provided of the O-ring type, mounted in grooves 30 and 31 of the housing end members 14 and 15 respectively.

Supported for rotation within the main housing 10 is a motor rotor assembly 10R, comprising a main supporting shaft 22 having a generally cylindrical rotor carrier 23 supported on a central portion thereof. The rotor carrier 23 has a plurality of axially elongated fluid passages 24 therein, and supports a laminated motor rotor or armature 25 of the induction type on the outer portion thereof.

The rotor carrier 23 is preferably formed in two symmetrical parts each having a flange 26, the two halves being pressed into the rotor assembly from opposite ends. The laminations comprising the armature or rotor proper 25 are also preferably embedded in an epoxy resin plastic compound and the outer, peripheral, surface is machined to an exact concentricity with the center of the bore 27 of the carrier 23. The supporting shaft 22 is then pressfitted into the carrier 23, such as by the heat-shrink method.

The rotor assembly also includes a pair of thrust wash.- ers or bearings 34 and 35, fitted tightly on the shaft 22 adjacent the opposite end surfaces of the carrier 23. The parts are preferably dimensioned relative to each other so that the carrier 23 is appreciably shorter than the space between the mutually confronting surfaces of the bearing portions 16 and 19. The thrust bearingsfl t and 35, in

cooperation with the ends of the sleeve bearings 18 and 21, serve to maintain the carrier 23 positioned generally centrally of the space between the bearing portions 16 and 19, so as to maintain spaces 36 and 37 at all times between the bearing portions and the corresponding ends of the carrier.

The housing end member 14 has a peripheral notch 38 providing a reduced portion which fits into the end portion of the main housing 10. The housing end member is provided with a circular groove 39 in one face, into which the opposite end portion of the housing 1!) fits. This facilitates assembly of the device by assuring exact alignment of the bearings 18 and 21.

When the parts thus far described are assembled, the bolts 32 are inserted through the housing end members and the openings provided in the stator assembly, and the nuts 33 are tightened, drawing the housing end members against the corresponding ends of the main housing 10, and at the same time compressing the O- rings 30 and 31 between the housing end members and the plasticembedded stator assembly. For additional sealing, a resilient type O-ring may also be included in the groove 39.

In FIGURE 3 there is shown a modified form of the invention utilizing a modified housing clamping arrangement. In this form, the housing end member 14 is provided with a flange 60, corresponding to flange portion of housing end member 15, and clamping bolts 32 are positioned outside of the main housing member 10, connecting the flanges of the members 14 and 15. This construction is suitable for larger sizes, in-which a larger number of clamping bolts are desired.

Referring again to FIGURE 1, for the purpose of propelling fluid through the device, a centrifugal type impeller 40 is provided, supported on an extension 41 of the shaft 22 which projects through the bearing 21, the impeller being held against a shoulder 41 on the shaft 22 by suitable means, such as by cap-nut 42. The impeller 40 is of the fully-shrouded type and includes openings 43 to permit equalization of fluid pressure on both sides of the impeller, thereby relieving end-thrust. While a particular type of centrifugal impeller has been shown, it is an important feature of the invention, as will be more fully set forth, that different types and sizes of impellers may be readily utilized and interchanged.

The impeller 40 preferably includes an inlet eye havmg a diameter equal to the distances between the outer portions of the passages of the housing end member 15.

For the purpose of enclosing the impeller, a generally cup-shaped impeller housing 44 is provided, including a fluid raceway and outlet coupling portion 45; The impeller housing also has a peripheral flange portion 46 which is adapted to be clamped against a corresponding portion of the housing end member .15 by suitable means, such as by means of bolts 47, with suitable sealing means, such as O-ring 48, therebetween.

To facilitate the connection of suitable conduit means to the intake end of the pump, the housing end member 14 is provided with a conduit adapter 49, mounted thereon by suitable means, such as by bolts 50, and including suitable sealing means such as gasket 51. It will of course be appreciated that various size conduit adapters may be utilized as desired, and that if desired, the conduit adapter 49 may be omitted entirely as a separate member and its function performed by an integral extension (not shown) of the housing end member 14 or by a cylindrical extension fitted into the recess 52 and suitably fixed in place, such as by welding.v

In operation, energization of the stator windings by alternating current creates a rotating magnetic field which in turn causes rotation of the rotor by action of the field associated with currents induced therein in the manner of a conventional induction motor. Rotation of the rotor causes similar rotation of the supporting shaft 22 and the impeller 40, which are fixed together as a dynamicallybalanced unit.

Rotation of the impeller 40 draws fluid in at the center or eye 40A and expels it at the periphery and out the discharge outlet 45 in a well-understood manner. The remaining portion of the main fluid flow path through the device is as follows: inwardly at the intake conduit adapter 49, through the passages 17 in the intake housing end member 14, through the passages 24 of the rotor carrier 23, through the passages 20 of the outlet housing end member 15, and into the intake or eye of the impeller.

The main portion of the fluid is thus afforded a straightthrough, substantially unobstructed flow path through the motor, in sodoing, passing over and around the main bearings of the motor shaft, affording maximum cooling to these parts.

In addition to the aforedescribed flow of the'main portion of the pumped fluid, important auxiliary flow paths are provided. Thus, in addition to the main flow of fluid around and over the bearing surfaces, fluid also flows through the bearings themselves, i.e., between the sleeve bearings 18 and 21 and the corresponding portions of the shaft 22 therein. This provides an effective forced lubrication and further cooling of the bearings.

Another auxiliary fluid flow path exists, moreover, through the motor chamber, the fluid flowing inwardly through the gap 36, over the inner surfaces of the stator assembly and through the air gap between the stator and rotor, and back to the main fluid flow path through the gap 37. Extremely effective and etficient cooling is therefore provided for both the motor stator and rotor.

It will be observed that access may be had to the impeller for inspection, replacement, etc., without disturbing the main bearings of the motor, by merely removing the impeller housing 44. The impeller may then be removed by removing the cap-nut 42, and a different size impeller may be mounted if desired. Moreover, if desired, the impeller housing 44 itself may also be changed to conform to a different size impeller, or to provide a diflerent size outlet opening and outlet connector.

Because of the embodiment and impregnation of the stator and rotor in epoxy resin, the motor-pump may be used as described for almost all clean liquids encountered in industry today, regardless of their chemical nature and without the necessity for a metallic partition or liner. There is thus afforded by the invention a pump of higher eificiency than heretofore available for applications involving corrosive or hazardous liquids.

In FIGURE 4 I have shown a modified form of the invention which is generally similar to the construction of FIGURES 1' and 2, but which is suitable for use in applications where it is desired to pump certain violently reactive liquids such as fuming nitric acid or sulphuric acid. In this form, I provide a cylindrical liner 54, constructed of a material which is compatible with the pumped liquid, such for example as a select stainless steel.

The combination disclosed in this figure, comprising a motor stator assembly which is solidly embedded in a plastic resin, together with a cylindrical facing liner of corrosion-resistant metal, has certain further important advantages for the pumping of such corrosive liquids. With this construction, it is possible to utilize an isolating liner which is appreciably thinner than would otherwise be required, since the backing provided by the solid body of plastic provides important support therefor. Conversely, it is possible to utilize the pump of this construction in pumping liquids under much higher pressures than would otherwise be possible, since the liner is thus enabled to withstand such pressures without deforming.

It will therefore be seen that I have provided a combination motor and pump in which the full flow of liquid being pumped is used to cool the motor bearings, windings, and rotor, and in which a high-pressure type centrifugal impeller is provided which is readily accessible for inspection and replacement and also one which is able to pump corrosive liquids at high efliciency and high pressures.

While only particular embodiments of the invention have been shown, it will be readily appreciated that many modifications thereof may be made by those skilled in the art, and I therefore intend by the appended claims, to cover all such modifications as fall within the true spirit and scope of the invention.

I claim:

1. A motor-pump comprising a generally cylindrical main housing, a generally cylindrical motor stator assembly supported in said housing, a generally circular intake housing end member supported on one end of said housing and having an axially elongated bearing portion centrally thereof, a generally circular outlet housing end member supported on the other end of said housing and having an axially elongated bearing portion centrally thereof, a motor rotor assembly comprising a supporting shaft having its ends rotatably supported in said bearing portions respectively, a motor armature portion supported on the intermediate portion of said shaft for rotation within said motor stator portion and spaced therefrom by a predetermined working air gap, said shaft including an end extension projecting through said outlet bearing portion, a fluid impeller supported on said extension, said intake and outlet housing end members and said rotor assembly all including axially extending contiguous fluid passage means, a first axial thrust bearing member on said shaft between said intermediate portion and said outlet housing end member, said armature portion having an axial dimension less than the corresponding axial distance between said bearing portions of said housing end members, and said thrust bearing members being dimensioned to retain said rotor assembly from more than a predetermined amount of axial movement and in a position spaced away from contact with both of said bearing portions, whereby fluid impelled by said impeller is drawn in through said intake housing end member and around both of said bearing portions before reaching said impeller, and the major portion of said fluid passes through said fluid passage means of said rotor assembly and a minor portion of said fluid passes through said space between said rotor assembly and said bearing portions and through said air gap between said armature portions and said stator portion.

2. A motor-pump as set forth in claim 1 wherein said impeller includes an inlet opening at least as large as the total areas of said fluid passage means of said rotor assembly and said outlet housing end member respectively and forms a direct axial continuation thereof.

3. An integral centrifugal pump and electric motor unit for pumping liquids, wherein the liquid to be pumped is passed axially completely through said unit to cool the same and then discharged radially thereof, which unit comprises in combination a torroidal stator assembly having a cylindrical outer shell enclosing a field pole and winding encased in plastic to provide substantially rigid, smooth surfaces at the inner periphery and opposite ends of said torroidal assembly, separate intake and outlet end members closing the ends of said last named assembly, said end members having, respectively, radially outwardly disposed surface portions mating with the end faces of said stator assembly to form a liquid-tight seal therewith and having inwardly thereof axially inwardly extending hub portions, said hub portions being apertured to provide axial fluid passages of a diameter comprising at least a major portion of the diameter of said stator torroid opening, cylindrical bearing supports disposed in said hub passages, the external diameter of said supports being a minor portion of the diameter of said stator torroid opening, bearings carried in said supports, and a rotor shaft journaled for rotations in said bearings, a rotor assembly secured to said shaft intermediate said bearings, said rotor assembly comprising an outer inductive portion having a smooth cylindrical surface disposed in closely spaced cooperative relation to said field pole surface, and a generally cylindrical carrier member for supporting said inductive portion on said shaft, said carrier member having an axial passageway extending therethrough in substantial registration with and constituting a virtual straight line continuation of said passages in said hub portions, said shaft including an end extension projecting through said outlet end member and a. centrifugal impeller secured on said shaft extension externally of the last said end member, and intake and outlet housings separably secured, respectively, to said intake and outlet end members, said inlet housing having a fluid passage directing fluid axially into and centrally of said unit, said outlet housing comprising a shroud for said impeller and including a radial discharge duct therefor.

4. A motor-pump unit as defined in claim 3, which further includes annular liquid seal means disposed between said end faces of said stator torroid and the respective intake and outlet end members.

5. A motor-pump unit as defined in claim 3, wherein said bearings are axially elongate sleeve bushings.

6. A motor-pump unit as defined in claim 3, wherein the diameter of said fluid passages in both said end member hubs and said rotor carrier are equal.

References Cited in the file of this patent UNITED STATES PATENTS 1,551,295 Fletcher Aug. 25, 1925 1,580,861 Schurch Apr. 13, 1926 1,996,460 Coates Apr. 2, 1935 2,312,848 PeZZillo Mar. 2, 1943 2,485,408 Pezzillo Oct. 18, 1949 2,524,269 Patterson Oct. 3, 1950 2,782,720 Dochterman Feb. 26, 1957 FOREIGN PATENTS 116,592 Australia Feb. 16, 1943 525,935 Belgium Feb. 15, 1954

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