US2519264A - Commutator - Google Patents

Description

Aug. 15, 1950 c. LYNN 2,519,264

COMMUTATOR Filed Aug. 31, 1948 I'll" g illlllmn WITNESSES: INVENTOR C'Zaren ce 15/2221.

467M BY Patented Aug. 15, 1950 COMMUTATOR Clarence Lynn, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 31, 1948, Serial No. 46,984

(Cl. lib-321) 7 Claims.

My invention relates to various improvements in V-ring commutators, particularly long V-ring commutators of 18 inches axial length or longer, for large direct-current motors or generators or other dynamo-electric machines.

An object of my invention is to make a commutator which is longer than is practically possible in the usual commutator-construction, even when the commutator-bars are made extremely deep in the axial direction. The usual commutator-construction is one in which .a V-ring is provided at each end of the commutator.

Heretoiore, it has been proposed to build commutators with three, or four, or more V-rings; and a three-V type of construction has actually been used. However, these types of construction, as previously known, have not produced a successfully operating unit, and their use has been abandoned. A moresuccessful type of construction for long commutators has been a two-V construction having one or more shrink-rings disposed around the .commutator, between its ends, but this construction is costly, and .the shrink-rings take up space on the commutatorsulrface, where brushes might otherwise run. Some manufacturers have used two commutators in tandem, when extra high current-capacity has been required, but such a construction is troublesome as well as expensive.

Anobject ofmy invention is to provide amodifled V-ring type of construction in which, instead of having only two V-rings, one at each end, the commutator is mounted on, .and in fact built or assembled around, a plurality of pairs of internally disposed V-rings, which are completely opened apart when the commutator-bars are being assembled, and which are drawn together towards each other, in pairs, to tighten the bars in position.

Other objects-of my invention include the provision of aplural-V commutator, or evena two-V commutator, having means for providing for either radial or axial expansion, or both, and/or having means for adding a spring-action to the bolt-force for always keeping the commutator tight.

v.A :further object is .to provide special bolts, :for the rear set .of rings, that can be tightened at the :accessible end.

With the foregoing and other objects :in view, my invention consists in the combinations, assemblies, parts, structures and methods, hereinafter described and claimed, and illustrated in the accompanying drawing, wherein:

, Figure 1 is. airagmentary longitudinal-sectional view of a dynamo-electric machine embodying a simple formof construction of my improved commutator,

Figs. 2 and 3 are fragmentary longitudinal sectional views of alternative forms of construction'of a V-ring, and

Fig. 4 is a fragmentary longitudinal sectional view of a plural-V-ring commutator-assembly having a modified clamping-bolt construction in which all of the bolts are accessible from the front end.

In Fig. -1, I have shown my invention applied to a dynamo-electric machine, such as a large direct-current motor or generator, having a stator or field-member G, and having a rotor- .member .5 comprising an armature-core 6 which .is mounted on a rotor-spider I carried by a shaft 8. The armature-core 6 carries an armaturewinding having end-terminals H) which are connected to .thenecks l l of the copper commutatorbars l2.

In accordance with my present invention, each of the commutator-bars l2 has a plurality of .dovetail projections 13 and it along its underor inner edge, with enough space between the projections so that the commutator-bars can be assembled as hereinafter described. The left-hand dovetail projections 13 of all of the bars are-engaged by a pair of steel V-rings, l5 and [8, which are first overlaid with mica (or other insulating) V-rings I5 and 16', respectively. The steel V- rings 15 and it are drawn axially together, as by means of bolts l'l, to tightly clamp the ends of the left-hand dovetail projections iii. In like manner, the right-hand dovetail projections M of allof the bars are engaged by another pair of steel V-rings, l8 and [9, which are first overlaid with mica (or other insulating) V-rings I8 and 1.9, respectively. The steel V-rings i8 and I9 are drawn axially together, as by means of bolts 20, to tightly clamp the ends of the right-hand dovetail projections I4.

The process of assembling the several copper commutator-bars 12 to make up a cylindrical commutator-assembly is different, in my invention, than in the ordinary two-V commutator. In the process of making an ordinary two-V commutator, the several commutator-bars are first assembled on a temporary drum or former, and then wrappedaround with a temporary binding, after which the drum or former is removed, and the two steel V-rings are applied. In the process of making my new multi-V commutator, a temporary drum or former is not necessarily .used, because the inside steel V-rings l6 and I8 are used for this purpose, after first being moved axially so that they clear the dovetail projections l3 and 14. This is why an adequate axial separation must be provided between the dovetail projections I3 and I4. After all of the copper bars l2 have been assembled (with the usual mica spacers, not shown, between them), the two outside or end steel V-rings i5 and I!) are applied, and tightened up with the bolts H and 20, after which the cylindrical commutator-assembly can be baked, and turned, and seasoned, in any ordinary manner.

While I have illustrated my multi-V commutator with only two dovetail projections l3 and I4, and two pairs of steel V-rings I5, l6 and l8,

l9, it will be obvious that any necessary number of dovetail projections may be used, with a corresponding number of pairs of steel V-rings,,

so that the commutator may be made as long, axially, as may be desired.

It is usually necessary, in successfully practicing my invention, to provide means for accurately centering the commutator with respect to the center-line (E of the shaft 8, while at the same time providing for the necessary axial movement to make up for the thermal expansions and contractions, which are necessarily large, because my invention is applicable only to commutators which are of unusually great axial length. To this end, I weld the inner periphery of the right-hand steel V-ring l9 to a solid centering support 22, which may have a press-fit on the shaft 8, and I preferably weld the inner periphery of the left-hand steel V-ring l5 to a flexible centering support 24, which may be keyed or otherwise secured to the shaft 8. The flexible centering support 24 has a disk-like wall which is sufficiently flexible to let the commutator expand and contract in an axial direction without imposing undesirable strains on the commutator. 1

Any number of flexible centering supports, similar to 24, may be used, in case a plurality of (more than two) pairs of steel V-rings are used.

It will be understood that the solid centering plate 22 might be disposed at either end (or other point) under the commutator.

In Fig. 2, I show a special form of steel V-ring 26 which may be used in place of either one or both of the centered V-rings IE or H? of Fig. 1, on either a multi-V or a two-V commutator. In Fig. 2, underneath the bolt-holes 27, the V-ring 26 is provided with a circular groove 28, which is machined therein so as to provide for radial expansion, while centering the commutator, The inner periphery of the steel V-ring 26 ,is welded to the outer periphery of either a stiff or a flexible centering plate or disk 29, which is adapted to be secured to the shaft 8 as shown in Fig; 1.

Fig. 3 shows an additional improvement for always securing tightness on the bolts ll or 20 of Fig. 1. Here, the steel V-ring 26' is provided with a radial groove 30 which is cut in the V-ring to give spring-action to the bolt-force of the bolts (not shown in Fig. 3) which go through the boltholes 27, for always keeping the commutator tight. In addition, the steel V-rin of Fig. 3 also has the circular groove 28 of Fig. 2, and either a stiff or a flexible centering plate or disk 29, a flexible plate 29 bein shown in Fig. 3, and being offset so as not to interfere with the cutting of the radial groove 30.

Fig. 4 shows a modification of the commutatorassembly of Fig. 1, in which the two front V-rings l5 and 16 are provided with extra bolt-holes 31', in positions intermediate between the bolt-holes which hold the clamping-bolts l1; and the rearend clamping-bolts 20' are provided with an intermediate shoulder 38, and with front extensions 39 extending through the extra bolt-holes 31. The front ends of these front extensions 39 of the rear bolts 20' are provided with squared heads or ends M] which are accessible from the front end of the commutator-assembly.

It will be understood that various changes may be made, in dimensions, shapes, numbers of parts, methods of construction, and other details, without departing from the essential novelty of my invention, particularly in its broadest aspects. I desire, therefore, that the appended claims shall be accorded the broadest scope of interpretation consistent with their language.

I claim as my invention:

1. A commutator-cylinder assembly for a dynamo-electric machine, comprising a plurality of commutator-bars, each having a plurality of dovetail projections along its under edge, and a plurality-of pairs of clamping V-rings, one pair for each dovetail projection, with means for drawing" the two rings of each pair axially together, so as to tightly clamp the ends of the associated dovetail projection, one or more of said clamping V-rings having a flexible centering-support with respect to the center-line of the shaft of the machine whereby the centered ring or rings have some freedom of axial motion.

2. A commutator-cylinder assembly for a dynamo-electric machine, comprising a plurality of commutator bars, each having a plurality of dovetail projections along its under edge, and a plurality of pairs of clamping V-rings, one pair for each dovetail projection, with means for drawing the two rings of each pair axially together, so as to tightly clamp the ends of the associated dovetail projection, one V-ring of one pair having a solid centering-support with respect to the center-line of the shaft of the machine whereby there is substantially no freedom of axial motion, and a V-ring of another pair having a flexible centering-support with respect to said center-line whereby said V-ring has some freedom of axial motion.

3. A commutator-cylinder assembly for a dynamo-electric machine, comprising: a plurality of commutator-bars, each having a plurality of dovetail projections along its under edge; a plurality of pairs of clamping V-rings, one pair for each dovetail projection of the assembly bars, each V-ring having a plurality of bolt-holes; and a plurality of axially extending clamping-bolts in said bolt-holes, for drawing the two rings of each pair axially together, so as to tightly clamp the ends of the associated dovetail projection; the /-rings other than the last two having extra bolt-holes, and the clamping-bolts other than the front ones having front extensions extending through said extra-bolt holes so as to be accessible from the front end of the commutator assembly. 4. A commutator-cylinder assembly for a dynamo-electric machine, comprising a plurality of commutator-bars, each having one or more dovetail projections along its under edge, a pair of clamying V-rings for a dovetail projection of the assembled bars, each V-ring having a plurality of bolt-holes, and a plurality of axially extending clamping-bolts in said bolt-holes, for drawing the two rings axially together, so as to tightly clamp the ends of the dovetail projection, the inner periphery of at least one of said clamping'V-rings having a centering-support with re spect to the center-line of the shaft of the machine, said centered ring or rings having a circular groove which provides for a certain amount of radial expansion, while centering the commutator.

5. A commutator-cylinder assembly for a dynamo-electric machine, comprising a plurality of commutator-bars, each having one or more dovetail projections along its under edge, a pair of clamping V-rings for a dovetail projection of the assembled bars, clamping means for drawing the two rings axially together, so as to tightly clamp the ends of the dovetail projection, at least one of said clamping V-rings having a radial groove therein, said clamping-means engaging the portion of said V-ring back of said radial groove so as to give spring-action to the clamping-pressure which is exerted by the clampingmeans on said dovetail projection.

6. A commutator-cylinder assembly for a dynamo-electric machine, comprising a plurality of commutator-bars, each having one or more dovetail projections along its under edge, a pair of clamping V-rings for a dovetail projection of the assembled bars, each V-ring having a plurality of bolt-holes, and a plurality of axially extending clamping-bolts in said bolt-holes, for drawing the two rings axially together, so as to tightly clamp the ends of the dovetail projection, at least one of said clamping V-rings having a radial groove therein, said clamping-bolts engaging the portion of said V-ring back of said radial groove so as to give spring-action to the boltforce which is exerted by the bolts on said dovetail projection.

7. A commutator-cylinder assembly for a dynamo-electric machine, comprising a plurality of commutator-bars, each having one or more dovetail projections along its under edge, a pair of clamping V-rings for a dovetail projection of the assembled bars, each V-ring having a plurality of bolt-holes, and a plurality of axially extending clamping-bolts in said bolt-holes, for drawing the two rings axially together, so as to tightly clamp the ends of the dovetail projection, the inner periphery of at least one of said clamping V-rings having a centering-support with respect to the center-line of the shaft of the machine, said centered ring or rings having a circular groove which provides for a certain amount of radial expansion, while centering the commutator, and said centered ring or rings also having a radial groove therein, said clamping-bolts engaging the portion of said centered ring or rings back of said radial groove so as to give spring-action to the bolt-force which is exerted by the bolts on said dovetail projection, the centered inner periphery of said ring or rings being oifset axially to one side of said radical groove. CLARENCE LYNN.

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

UNITED STATES PATENTS Number Name Date 504,379 Warner Sept. 5, 1893 678,171 Geisenhoner July 9, 1901 1,512,221 Haughton Oct. 21, 1925 2,045,405 Penny June 23, 1936 FOREIGN PATENTS Number Country Date 350,274 France Oct. 30, 1905 445,461 Germany June 10, 1927

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