US2501370A - Floating-seal commutator - Google Patents

Description

March 21, 1950 w. L. WRIGHT 2,501,370

FLOATING-SEAL CONMUTATOR Filed Jan. 21, 1949 INVENTOR WITNESSES: Y

Willard L.Wright.

v ATTORNEY Patented Mar. 21, 1950 FLOATING-SEAL COMMUTATOR Willard L. Wright, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 21, 1949, Serial No. 71,845

3 Claims. 1

The present invention relates to commutators for dynamo-electric machines, and more particularly to commutators oi the V-ring type. My invention was particularly designed for a railway-type traction-motor, but its general prin-- ciples are applicable to other types of dynamoelectric machines.

More particularly, the present invention relates to a novel method and means for providing a seal which will not allow dirt or foreign matter to get into the V-ring assembly in such manner as to cause an electrical short between the bars of the commutator. Usually, such a seal is provided b causing the clamping V-rings to enter far enough into the V-grooves in the ends of the commutator-bars, so as to make a wedgingcontact, pressing radially outwardly on the ends of the bars, in addition to the arch-binding contact which is made by the inclined inner surface of the clamping-V-rings, pressing against the corresponding surfaces of the V-grcoves in the bars. The necessity for providing this wedgingaction, in order to seal the upper inclined surfac of the V-rings, and the upper inclined surfaces of the V-grooves of the bar, so as to prevent the entrance of dirt, has heretofore resulated in considerable difliculty, due to the nonuniformity of the thickness of the insulating V- rings which have to be provided, thus resulting in a variation in the outward pressure which is exerted against the extreme ends of the commutator-bars, causing non-uniform deflection of these ends or overhanging portions of the commutator-bars, producing a rough surface for the commutator-brushes to slide upon.

The sealing-difficulties of V-ring commutators have often been attacked heretofore, but are still with us. To mention only two means which have been adopted heretofore, to combat the sealing-trouble, reference may be made to a Dick Patent 2,351,021, and a Mueller Patent 2,426,042. In the Dick commutator, the wedging-action of the clamping V-ring was omitted altogether, resulting in a small open space between th upper inclined surface of the clamping-V-ring and the upper inclined surface of the v grooves in the commutator-bars, and this small open space was closed by a kind of resilient sealing-means which was applied externally around the insulating V-rings at each end of the commutatorbar assembly. In the Mueller commutator, a special construction was provided, in which both the clamping V-ring and the V-groove of the commutator-bars were provided with cylindrical,

or non-inclined surfaces, which could be sealed without any wedging-action.

The object of my present invention is to provide a novel form of V-ring seal, making it possible to use a commutator-construction which is entirely arch-bound, without any wedging-ac tion of the clamping V-rings, by using either a resiliently expanding ring or a floating ring, which is provided in a groove in the clamping-V- ring, near the end of th associated V-groove of the commutator-bars, forcing the associated insulating I-ring outwardly into a dirt-sealing engagement with the outer surface of the associated V-groove at the entrace to said V-groove.

With the foregoing and other objects in View, m invention consists in the combinations, parts, means, methods, processes and general and specific forms of embodiment, hereinafter described and claimed, and illustrated in the accompanying drawing, wherein,

Figure 1 is a fragmentary longitudinal sectional view of the commutator-end of a dynamoelectric machine embodying my invention, and

Fig. 2 is a similar view of one end of the commutator, showing another form of embodiment which is in some respects preferred.

1 have shown my invention applied to a commutator-type dynamo-electric machine in the form of an alternating-current railway-traction motor, comprising a stator-member l and a rotor-member 2, the latter being mounted on a shaft 3 and carrying a substantially pre-seasoned V-ring commutator-assembly 4 in accordance with my present invention. The commutator-assembly is made up of a number of copper commutator-bars 5, separated by mica or other insulating bars 6, th two kinds of bars being of similar size and shape, except that the insulating bars commonly project back about A; of an inch behind the commutator-bars, as indicated by the numeral 6, that is, the mica bars 6 are longer than the copper bars 5. The bars 5 and 6 are provided with V-grooves l in the ends thereof, said V-grooves having inclined inner, arch-binding surfaces 8, usually at a 30 angle, and outer surfaces 9, usually at a 6 angle.

The V-grocves I are insulatingly engaged by clamping V-rings l I, usually of steel, having inner conical surfaces i2, inclined at an angle matching the inner archbinding surfaces 8 of the V-grooves, and outer surfaces [3, inclined at an angle usually matching the outer surfaces 9 of the V-grooves.

The insulating engagement is provided through the intermediary of insulating V-rings l4, preferably made of sheet-mica of sufficient thickness to withstand the maximum voltage which is applied to the commutator-member. The relative dimensions of the clamping V-rings and the V-grooves are such that the groove-entering portions of the insulated inner, conical surfaces ll. of the clamping V-rings tightly engage the respective inner, arch-binding surfaces 8 the v-grooves, with the insulating V-rings l4 interposed in between, and with the insulated outer surface l3 of each clamping -ring spaced out of pressure-transmitting engagement as indicated at l5, with respect to the outer surface 9 of the associated \"-greove. The outer surface H) of each V-rin'g H, with its superposed portion of the mica l-ring US, also has an extended portion 16 which extends out of the V-groove, beyond the end of the commutator-member, and which is cemented. or otherwise secured to the corre sponding portion of the clamping V -ring l i, which may he a slightly raised surface 1 9 as shown.

In accordance with my present invention, I not only provide the clearance-space l5 between the outer surfaces of the insulated clamping V-rin 's the l -g ooves, but I also provide means for flexibly sealing the entrance to each of these clearance-spaces [5, against the accidental entry of foreign matter thereintc. This sealingneans may take any one of several different f ns, two of which are illustrated in the accompanying drawi As shown in the drawing, I provide the outer inclined surface E3 of one or both (preferably both) of said clamping -rings ll with a groove 2! therein, near the end. of the associated V-groove l of the co1n1nutator-bars 5, and I use this groove 2i to a self-adjusting ring, which is shown. in 1 as a resiliently expanding ring 22, which is disposed in said groove, for forcing the associated insulating V-ring Hi out into dirtsealing engagement with the outer surface l5 of the associated V-groove l, at the entrance 23 to said V'QIOOVQ. This resiliently expanding ring 22 may be made either of rubber or a rubberlike composition, or it may be formed of hightensile steel such a curve that when it is compressed in the groove and assembled with the commutator-bars, the ring will be round and will exert a UL. form radial force against the underside of the insulating V-ring Hi, and hence against the ends of the commutator-bars 5, similar to a piston-ring in a-piston--engine.

he operation of my invention, as in i is at once apparent. My clamping J--rings "age the commutator-bars 5 with only an archiding force which is exerted between the two inclined surfaces l2 and through the intermediau'y of the interposed insulating mica V-ring M. The clamping V-ring ll does not enter into any wedging engagement with the V-groove l of the commutator-bars 5, and hence there is no difficulty due to unequal or excessive outward pressure against the extreme ends of the i -grooved commutator-bars. The resiliently expanding ring it, on the other hand, exerts a gentle and absolutely controllable force, just enough to safely close the opening between the top of the 1 ca V-ring Hi and the top inclined of the V-grocve l in the commutatorbars In assembling the commutator-structure, it is a simple matter to hold the resiliently expanding ring Zicompressed, if necessary, by a simple encircling tool (not shown), while forcing the insulation-covered clamping ll-rings H into clamping-engagement with the V-grooves I in the two ends of the commutatonbar assembly l.

In the form of my invention shown in Fig. 2, the self-adjusting ring 22 is a solid steel ring 22' which has a loose fit in the groove 2!, so as to provide clearance so that the loose ring 22 may assume an eccentric position in the groove 2i. or it may assume a not-quite-circular shape, when necessitated by any non-uniformity in the thickness of the mica V-ring l4. Thus, I obtain the sealing ability of a V -bound commutator, without the chance of excess pressure on the G-degree copper overhang surface 9, in a commutator which is substantially entirely arclubound.

An outstanding advantage of the solid 1 ring 22' of Fig. 2, over the expanding ring L! Fig. i, is that the solid ring 22 is much stron er, so that the commutator-bars 5 will withstand an appreciable blow on their overhanging ends, without bending at these ends. This is a decided advantage over a purely arch-bound commutator, which must be handled very carefully in order to prevent damage to the overhanging ends of the copper bars.

In 2, also, by way of illustration, the end of the mica V-ring M, which overlies the ra'sed ledge i l of the clamping V-ring H, is held do n, against centrifugal force, by string-binding 24, which is the preferred securing-means.

I claim as my invention:

1. A commutator-cylinder for a dynamo-electric machine, said commutator-cylinder comprising plurality of com1nutator-bars having V-grooves in the ends thereof, said ll-grooves having inclined inner, arch-binding surfaces; insulating V-rings; clamping V-rings having inner. conical surfaces tightly engaging the inner, archbindng surfaces of the V-grooves, with the insulating i' rings interposed in between; the insulatio:i.covered outer surface of one or both of said clamping V-rings being spaced out of prossurc transmitting engagement with respect to the outer surface of the associated \hgroove; said outer surface of said one or both of said cl? ing brings having a groove therein near the on of associated V-groove; and a self-centering ring, disposed in said groove, for forcing the associated insulating V-ring out into a dirt-sealing engagement with the outer surface of the associated V-groove at the entrance to said V-groove.

A commutator-cylinder for a dynamo-electric machine, said commutator-cylinder comm ing a plurality of commutator-liars ha r: \/--grooves in the ends thereof, said Wgrooi'es having inclined inner, arch-binding surfaces; in sulating inings; clamping V-rings l'iaving inner, conical surfaces tightly engaging the inner, archbinding surfaces of the -l-grooves, with he insulating V-rings inter grose. in between: the insulation-covered outer surface of one or both of said clamping V-rings being spaced out of pressure-transmitting engagement with respect to the outer surface of the associated V-groove; said outer surface of said one or both of said clamping V-rings having a groove therein near the end of the associated V--groove; and a res tly expanding ring, disposed in said groove, for forcing the associated insulating V-ring out into a dirtsealing engagement with the outer surface of the associated V-groove at the entrance to said V-groove.

3. commutator-oylinder for dynamo-electric machine, said commutator-cylinder comp'ising a plurality of commutator-bars having V-grooves in the ends thereof, said -/grco'.'es having inclined inner, arch-bincing surfaces; insulating V-rings; clamping V-rings having inner,

6 the associated V-groove; and a loosely fitting solid ring, disposed in said groove, for forcing the associated insulating V-ring out into a dirtsea1- ing engagement with the outer surface of the associated V-groove at the entrance to said V-groove.

WILLARD L. WRIGHT.

No references cited.

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