US2515973A - Totally enclosed motor - Google Patents

Description

y 1950 w. D. ABBoi-T 2,515,973

TOTALLY ENCLOSED MOTOR Filed Dec. 17, 1948 WITNESSES: tNVENTOR Quid M WM Wmd 0. Abbm-i.

Patented July 18, 1950 TOTALLY ENCLOSED MOTOR Ward D. Abbott, Orchard Park, N. Y., assignor to Westinghouse Electric Corporation, East Pittaburgh, Pa., a corporation of Pennsylvania Application December 17, 1948, Serial No. 85,924 6 Claims. (Cl. 172-36) My invention relates to totally enclosed fancooled motors, and it has particular relation to the means for transferring heat from the enclosed air to the end-brackets of the machine.

In conventional designs of totally enclosed fancooled squirrel-cage motors, it has been noted that heat has been removed satisfactorily from the coil-ends of the stator-winding and from the rotor-member to the internal air, but that this heat has not been satisfactorily transferred to the enclosure. In these previous designs, there has been a separate pocket of air at each end of the machine, within the imperforate end-brackets of the machine, and the air, in each of these brackets. has been circulated by means of fan-blades which project axially from the respective ends of the squirrel-cage rotor-member, so as to blow air readily outwardly against the end-turns of the stator-winding, at that end of the machine, after which the air circulates around, past the inner surface of the imperforate end-bracket at that end of the machine, and enters the fan-blades again, from underneath.

The object of my invention is to provide an additional internal blower, preferably a blower at each end of the rotor-member, this blower being located just inside of the inner surface of the imperforate bracket at that end of the machine, out of contact therewith, of course, so that the air-pocket at each end of the machine, inside of the enclosure, is doubly stirred or churned, with two paths of air blowing radially outwardly, one path being generated by the rotor-blades which are integral with the squirrel-cage winding so as to blow radially outwardly against the statorturns, while the other path of circulating air is generated by the newly added internal blower, which blows air radially outwardly against the internal surface of the imperforate bracket at that end of themachine. These two air-paths mingle together and come back toward the shaft of the machine, where they separate again and are recirculated by their respective fan-blades or internal fan. By means of this inexpensive expedient, I have been able to appreciably reduce the motor-temperature, for a given rating, or to appreciably increase the rating, for a given temperature-rise.

With the foregoing and other objects in view, my invention consists in the combinations, structures, assemblies, parts, and methods of design and operation, hereinafter described and claimed, and illustrated in the accompanying drawing, the single figure of which is a longitudinal sectional view of a motor embodying my invention.

As shown in the drawing, my invention is applicable to a totally enclosed squirrel-cage motor or other dynamo-electric machine. comprising a frame-ring I, having a stator-core 2 secured within the same. At a plurality of points around the periphery of the stator-core 2, limited-area contacts are made with the inside of the framering I, the stator-core being radially spaced, at other places around its periphery, from the inner periphery of the frame-ring to provide a plurality of axially extending vents I. The stator-core 2 carried a stator-winding 4 which has end-turns I.

The motor also has a shaft I, which carries a rotor-core 1 which rotates within the stator-core 2. The rotor-core 1 carries a cast squirrel-cage rotor-winding l, which has integrally cast, axially extending fan-blades 9 at each end thereof.

.The machine is provided with two imperforate end-brackets II and it, which are mounted on the machine, one at each end, each bracket making an air-tight joint with its end of the statorcore 2, and each of these imperforate brackets having no air-hole therein. Each of said imperforate brackets II and I2 has a bearing II for supporting the shaft 8 at that end of the machine.

In accordance with a known practice, an external fan I 4 is mounted on the shaft 0, outside of, and close to, the imperforate bracket I I at one end of the machine. Also in conformity with a known practice, the machine is provided with two end-hoods l5 and it, which provide hood-like extensions of the frame-ring I, in spaced relation to the respective imperforate brackets H and l2.

The external fan I! is disposed within the space between the imperforate bracket II and the corresponding end-hood II. in spaced relation to both of these stationary parts, so that air is drawn by the external fan It, and forced over the outside of the associated imperforate bracket ll, then axially through the vents 8, and then over the outer periphery of the other imperforate bracket 12, thus externally cooling both of the imperforateend-brackets H and ii.

In accordance with my present invention, an internal fan 2| is mounted on the shaft I, inside of, and close to, the imperforate bracket H at the end of the machine at which the external fan H is located, and preferably also, a similar internal fan 22 is mounted on the shaft in corresponding relation to the imperforate bracket I! at the other end of the machine.

The result of this construction is a double churning-effect, with respect to the air-pockets II at each end of the machine. It will be understood that these air-pockets are substantially segregated from each other, because neither the stator-core 2 nor the rotor-core I has any axially extending vent therein. As a result of my fanconstruction, the rotor fan-blades 3 at each end of the rotor-core I blow the air in its air-pocket radially outwardly over the end-turns 5 of the stator-winding I, at that end of the machine, as shown by the arrows 3|, while the internal fan 2| or 22, as the case may be, blows the air of its air-pocket radially outwardly over the internal surface of the imperforate bracket H or H, as the case may be, at that end of the machine, as shown by the arrows 32. These two air-paths, as indicated at 3| and 32 respectively, then commingle and flow back together toward the shaft of the machine, and then are drawn, by their respective fan-blades 9 and'internal blower 2| or V 22, so as to recirculate in the paths just described.

The effect of the fan-means just described is to blow a blast of internal air strongly against and along the internal surface of each of the enclosure-brackets II and I2 of the machine, so as to strongly cool the internal air of the machine, by causing it to give up its heat to the respective imperforate end-bracketsv II and |2. These imperforate end-brackets II and I2 are advantageously'provided with internally extending ribs 34, to increase the effective cooling-surface area of the brackets.

In the over-all operation of the totally enclosed fan-cooled motor, the external draft of air, which is blown over substantially the entire motorenclosure, by the external fan It, effectively cools the two imperforate end-brackets and I2, as well as the outer periphery of the stator-core 2. Much of the heat of the stator-member thus passes radially outwardly to the portion of the core-periphery which bounds the axially extending vents 3, and is there transferred to the external air-stream which flows axially through these vents.

However, practically all of the heat of the rotor-member, and much of the heat of the endturns 5 of the stator-winding 4 has to be transferred to the internal air at the respective ends of the machine, inside of the respective imperferate end-brackets I I and I2, and this heat-transfer to the internal air is accomplished without any difliculty. The difficulty has ben experienced, in the past, in getting the heat out of this internal air into the respective imperforate end-brackets II and 2, the outside surfaces of which are effectively cooled by the external blast.

It will be noted that any present invention, by providing two oposed air-streams 3| and 32, in each of the end-pockets of the machine, thereby churning up the internal air in recirculating paths 3| and 32 which commingle with each other, after passing their respective heat-transfer surfaces, supplies an amount of effective cooling to this internal air, which is commensurate with the importance of the function of this internal air in withdrawing heat from the rotormember and from the stator end-turns of the machine. Experience has shown that totally enclosed machines which are provided with my internal fans 2| and 22 operate appreciably cooler than totally enclosed machines without this addition, when having the same rating, and contrariwise, if the same internal machine-temperature is allowed, in each case, the ratings of my ma chine can be appreciably increased over the ratings which are permissible without the specially added internal fans 2| and 22.

4 While I have described my invention in a single preferred form of embodiment, I wish it to be understood that my invention is not limited to this precise form, as 'many changes may be 5 made, in the way of additions, omissions and the substitution of equivalents, without departing from the essential spirit of my invention, in its broader aspects. I desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language.

I claim as my invention:

1. A totally enclosed dynamo-electric machine comprising a frame-ring, a stator-core secured within said frame-ring, at least a portion of the outer periphery of the stator-core being radially spaced from the inner periphery of the framering to provide an axially extending vent, a stator-winding carried by the stator-core, said stator-winding having end-turns, a shaft, a rotor-core carried by the shaft, a cast squirrelcage rotor-winding carried by the lOtOl-yCOI'B and having axially extending fan-blades at each end thereof, two imperforate brackets mounted on the machine, one at each end, each imperforate bracket having no air-hole therein and having a bearing for supporting the shaft at that end of the machine, an external fan mounted on the shaft outside of, and close to, one of the imperforate brackets, an endhood surrounding said external fan and the associated imperforate bracket in spaced relation thereto for directing the air from said external fan over the outside of said associated imperferate bracket and axially through said vent outside of the portion of 'the outer periphery of the stator-core, and an internal fan mounted on the shaft inside of and close to, said externally cooled imperforate bracket, for transferring the heat of the internal air to the internal surface of the said imperforate bracket.

2. A totally enclosed dynamo-electric machine comprising a frame-ring, a stator-core secured within said frame-ring, at least a portion of the outer periphery of the stator-core being radially 45 spaced from the inner periphery of the frame-ring to provide an axially extending vent, a statorwinding carried by the stator-core, said statorwinding having end-turns, a shaft, a rotor-core carried by the shaft, a cast squirrel-cage rotor- 60 winding carried by the rotor-core and having axially extending fan-blades at each end thereof, two imperforate brackets mounted on the machine, one at each end, each imperforate bracket having no air-hole therein and having a bearing 88 for supporting the shaft at that end of the machine, external ventilating-means 'for causing an external air-circulation over the external surfaces of both of said imperforate brackets and in said axially extending vent, and two internal fans 30 mounted on the shaft, one of said internal fans being inside of, and close to, each imperforate bracket, for transferring the heat of the internal air at each end of the machine to the internal surface of the imperforate bracket at that end.

3. The invention as defined in claim 2, characterized by neither the stator-core nor the rotorcore having any axially extending vent, whereby the internal air at each end of the machine is substantially isolated from the internal air at the 70 other end of the machine, and whereby each'of said internal air-pockets is doubly churned by the rotor tan-blades and by the internal fan at that end of the machine, the rotor fan-blades blowing the air radially outwardly over the end-turns of 16 t e s a or winding at that end of the machine,

and the internal fan blowing the air radially outwardly over the internal surface of the imperforate bracket at that end of the machine.

4. The invention as defined in claim 3, characterized by the inner surface of each imperforate bracket being ribbed.

5. The invention as defined in claim 2, characterized by the inner surface of each imperforate bracket being ribbed.

6. The invention as defined in claim 1, characterized by the inner surface of said fan-cooled imperforate bracket being ribbed.

WARD D. ABBOTT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,335,129 Schroeder Mar. 30, 1920 1,376,767 Selden Jr Sept. 12, 1932 1,928,416 Elley Sept. 26, 1933 2,043,655 Ehrmann June 9, 1936 2,185,728 Fechheimer Jan. 2, 1940

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