US2459673A - Dynamoelectric machine - Google Patents

Description

Jan. 18, 1949. E. o. MUELLER DYNAMOELECTRIC MACHINE Filed July 2, 1945 F INVENTOR [Hz/7 0 Muefler.

WITNESSES: 4%. 42%.

ATTORNEY not altogether perfect success.

Patented Jan. 18, 1949 DYNAMOELECTRI'C MACHINE Erich 0. Mueller, Irwin, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 2, 1945, Serial No. 602,868 3 Claims. (01. 171-.252)

My invention relates to dynamo-electric machines, and particularly to such machines having :a salient-pole stator member, and the invention relates particularly to an. improved spring-device for holding the field-coils tight on the poles of the machine.

For many years, field-coil springs have been inserted between the coils and the pole-face portions of the several poles, to assure a tight fit of the coil, and to prevent any coil-movement due .to vibration, or due to heating and cooling expansions and contractions, which might in time damage the coil-insulation. Many various forms of field-coil springs have been known and used, with Some of the troubles with such springs have been a nonuniform load-distribution, necessitating an extra washer to be placed between the spring and the .coil, in order to distribute the load sufficiently to prevent the non-uniform spring-pressure from impressing itself into the coil-insulation. Some trouble has also been experienced because of the cracking or breakage of heat-treated steel springs, permitting the broken spring-parts to work out of position, causing damage to the apparatus,

and this trouble had to be met .by providing additional means for preventing such displacement of the broken spring-parts, in case the spring should break.

As a result of the foregoing and other considerations, the usual forms of field-coil springs, including their washers, as heretofore employed, have had a thickness of about it; inch or more, between the coil-supporting surfaces of the poleface portion and the coil which is mounted on that pole. These field-coil springs have also been of rather complicated construction, involving a small, but not insignificant, manufacturingexpense.

An object of my present invention is to provide a spring-device which takes up a minimum of space, which provides a good heat-conducting contact, and which cannot fall out of position.

A more specific object of my invention is to provide a field-coil spring-device which has two longitudinally extending sheet material strips which are disposed, one on each side of the poleshank, each spring-strip being smoothly dished crosswise thereof, and being subject to arching compression. In this way, the effective length of the spring is only the crosswise width thereof, which may be of the order of 1 inch, on the types of machines to which my invention is particularly applicable, but the effective width of the spring equals the full length 0! the pole, measured longitudinally or axially of the machine, on each side of the pole, so that a rather large total springpressure may be exerted.

There are other advantages and details of my improved spring which will be pointed out hereinafter.

An exemplary form of embodiment of my invention is shown in the accompanying drawing, wherein:

Figure 1 is a transverse sectional view of a dynamo-electric machine embodying my invention,

Fig. 2 is a view of the blank from which one of my spring-members is made,

Fig. 3 is an end view of a finished spring, and

Fig. 4 is a fragmentary longitudinal sectional view through the machine, showing a side view of one of the poles, with my spring in position.

As shown in Fig. 1, my invention is applicable to a traction-type motor, or any type of alternating-current or direct-current machine which comprises a rotor member 5 and a salient-pole stator member 6. In the particular illustrated form of my invention, the stator member has a yoke or frame member 1, within which are secured a plurality of main poles 8, and a plurality of interpoles 9. In the particular form of invention which is illustrated, my field-coil spring-device is applied only to the main poles 8, where such devices are more urgently needed, but it will be understood, of course, that my invention is applicable to any or all of the salient poles 8 or 9 of the machine.

Confinin our attention, for the moment, to the plurality of main poles 8, it will be noted that each pole comprises a shank-portion ll, having thereon a coil-means comprising one or more field-coils i2. The pole-shank ll terminates in a pole-face portion i3, which comprises two circumferentially extending coil-supporting extensions it, each extending along the full length of a longitudinal side of said pole-shank portion ii, one coil-supporting extension i4 being disposed on each side of the pole.

The coil-supporting spring-means i5 is disposed between the coil-supporting extensions ll of the pole-face portion l3 and the coil-means l2 of each pole. In accordance with my invention, each coil-supporting spring-means i5 comprises two longitudinally extending sheet-material strips i6, each extending over the full length of one of the coil-supporting extensions H for the associated coil-means i2 between said coil-supporting extension and the coil-means. Each of the two longitudinally extending sheet-material strips l6 is smoothly dished crosswise thereof, being preferably curved on an arc of a circle as indicated at I! in Fig. 3. In this manner, when the dished strips l6 are deflected into their compressed condition, under arching compression, when the machine is assembled, theypresent an almost flat coil-supporting surface, which presents a fairly uniform pressure against the coil-insulation i8, thus requiring no extra washers for preventing damage to the coil-insulation. These springstrips I6 can be made of any suitable spring sheetmaterial, preferably beryllium-copper, or they may be made of a new alloy called Tempalloy," either of which is preferred to spring-steels, which require more diillcult heat-treatment, although spring-steels could be used. As an example of my invention, but not a limitation thereof, it may be noted that spring-pressures of the order of 150 pounds per linear inch may be obtained in this manner.

It is an essential feature of the coil-supporting spring-means ii, that some suitable retainingmeans shall be provided for retaining the two sheet-material strips ii in position on each side of their associated salient pole 8. A preferred form of retaining-means is shown, in the exemplary form of embodiment of the invention, comprised a bent lateral extension 2| of each longitudinally extending sheet-material strip [6, each bent lateral extension 2i being shorter than the longitudinal length of the strip 16, and being bent at such an angle that the bent lateral extension 2| fits into the space between the coil-means I2 and the longitudinal side of the associated poleshank portion ii, as shown in Figs. 1 and 4. This form of spring-retaining means has the advantage of requiring no spring-material which extends longitudinally beyond the salient polemember 8, that is, longitudinally beyond the pole-' face extensions M, where there would be no poleface extension to support the spring-material, and where the danger of bending and breakage would be encountered. My spring-retaining means 2i thus provides a means which is disposed within the confines of the salient-pole member 8, so that no portion of the spring extends into an exposed position where it might become bent or broken.

As indicated in Fig. 2, each spring-strip i6, with its associated bent lateral extension 2i, may be conveniently stamped out of an initially flat sheet of spring-material, after which the stripportion I6 may be dished, as shown at il in Fig. 3, and the lateral extension-portion 2| may be bent up into the position shown in Fig. 3. The spring-strips, thus formed, are applied to the pole 8 before the latter is secured to the yoke or frame member I, and before the coil-means i2 is applied. Thus, when the completely assembled pole 8, with its coil-means I2, is applied to the yoke l, and drawn up tight, as by means of the boltmeans 24, the dished strip-portions ii of the spring are deflected into their compressed flattened condition, in which they serve to prevent damage to the coil-insulation by reason of vibration or movement of the coils.

While I have illustrated my invention in a single preferred form of embodiment thereof, it should be understood that the invention is susceptible of embodiment in several different forms. I desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language.

I claim as my invention:

1. A dynamo-electric machine comprising a rotor member and a. salient-pole stator member, a plurality of salient poles of said stator member each comprising a pole-shank portion, a coilmeans on each of said pole-shank portions, a pole-face portion comprising circumferentially extending coil-supporting extensions along the full length of each longitudinal side of each of said pole-shank portions, and a coil-supporting spring-means for each of said plurality of salient poles, each spring-means comprising two longitudinally extending sheet-material strips, each extending over the full length of one of the coilsupporting extensions for that coil-means, between said coil-supporting extensions and the coil-means, each of said two longitudinally extending sheet-material strips being smoothly dished crosswise thereof, and being subjected to arching compression so as to present an almost fiat coil-supporting surface when the springmeans is deflected into its compressed condition, each of said spring-means comprising means for retaining said two sheet-material strips in position on their associated salient pole.

2. The invention as defined in claim 1, characterized by each of said spring-means having a longitudinal length about equal to the longi tudinal length of the coil-supporting extensions of the pole-face portions.

3. The invention as defined in claim 1, charac terized by the spring-retaining means comprising a bent lateral extension of each longitudinally extending sheet-material strip, each bent lateral extension being shorter than the longitudinal length of the strip, each bent lateral extension fitting into a space between the coil-means and the longitudinal side of the associated pole-shank portion.

ERICH O. MUELLER.

REFERENCES crrnn The following references are of record in the Name Date Priest Jan, 16, 1912 Number

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