US2468844A - Spring commutator - Google Patents

Description

-May 3, 1949.

C. H. SUTHERLAND SPRING COMMUTATOR Filed Jan. 10, 1948 atLa INVENTOR Carl HSuf/z e'rldzz a ATTORNEY Patented May 3, 1949 SPRING ooMM 'rAfro Carl Henry Sutherland, Pittsburgh, Pa, assignor to Westinghouse Electric Gorporatibn, East Pa, a corporation a): 'Bennsylyania Application January 10, 1943, Serial N0. 1 52 0 2 Claims (Cl. 17-1-32!) My. invention relates tothemechanical mounting. of commutator-cylinders for dynamo-electric machines, and it has more. particular relation to a new spring-mounting for holding the commutator-bars in place.

My invention is an improvement over the diskspring commutator of the Moore Patent 1,826,628 of. October 6, 1931', and the commutator processing of the Graybrook Patent 2,379,145 of June26, 1945, both patents being assigned tothe Westinghouse Electric Corporation.

An object of my invention'is to provide a spring-v cornmutator for railway locomotive tractionmo tors, or other purposes, which will allow the rotor-core to be lengthened by approximately 1% while using the same statorrframe, end.- brackets and comrnut ator-bar s;

A further object of; my invention is to provide, a spring-commutator mounting in which the, diskspring is mounted at the rear of the. commutator, where there is available room, butin. which the rear V-ring is in one piecewith the commutator-. spider, which is solid on the armature-spider, so that the commutator-ncks do not move axially toward and away from the armature-core so as to break the commutator-leads, asin certain, previous rear-spring commutators.

A further object of my invention is to provide a spring-commutator having not only a rear-v mounted disk-spring, but also a plurality of axially extending studs, which are subject to elongation in series with the disk-spring deflection, so asto decrease the change. in the, pressure which is exerted on the commutator-bars due to temperature-changes and speed-changes.

A still. further object of my invention is to provide a disk-spring commutator which can be retightened, after it is assembled, in the finished armature, without requiring the. armature to be placed under a press, as in previous designs, in order to, relieve, the pressurev on the tightening-, means before the. latter can be drawn up more tightly.

With the foregoing and other objects in view, my invention consists in the. novel. parts, structures, combinations and methods of assembly and use, hereinafter described and claimed, and illustrated in the accompanying drawing, the single figure of which is a longitudinal sectional view of the top half of the commutator-end of a railway locomotive traction-motor embodying my invention, with the brushes omitted for the sake of clarity.

My new spring-commutator is shown in the drawing as being applied to a series single-phase railway-motor havin a stator-frame I, carrying, a stator-corez, which in turn carries the varii'ms field-windings 3 of the. motor. The end. oi the statordrame' l carries an end-bracket 4 whieh is provided with a bearing 5. for supporting the motor-shaft 6. The shaftG carries the rotor or armature-spider l, on which is mounted! the armature-core 8 in cooperative. relation to the stator-core}. Thearm t r -c'ore 8, in turn, car.-v ries the armature-windings 9, having commuted; tor-leads IQ which, are connected to the neclrs ll of the, respective commutator-bars'lz which make up a cylindricalrsllli aced. commutator. l3 The extending portions of the anm'ature windings "9. and leads l0, whichextend outtowa'rdfthe com-Q mutator [Biromthe armature-core 8 are sup; ported on. a. cbre-endplate or cell-support l4 having. a forwardly extending cylindrical shoulgler l5 under which extends the rear V-ring l6 oi the commutator-supporting means.

The. commutator bars I 2 are provided with the usual V,-g rooves H at each end, and are held in place byv means of front and readfV-rings l8 and I6 Oneoi theseV-rings isintegral with a corn; mutator-spider I9 which is rigidly secured to a portion'of the armature-spider 'a'j, so that'itl is immovablewith respect to both the armature-core 8 and thecommutator-leads Ii) of thearmatura winding, 9. The, other V -ring slides axially on the commutator-spider I 9 so, as, to yieldably hold the commutator-bars, l2. in place.

As set forth in the previously mentioned patents, and. as shown at the rear end of my commutator. I3, a disk-spring 2|. is used to apply spring-pressure. to the. movable V-ring. Heretog fore, the disk-spring has been. placed at thesame end: of the commutator as the. movable. V.-ri ng', and when an attempt has been made to put the. disk-spring, and the movable V-ring, at. the rear, 'where. there. is ample room for the spring, the axial movement of the movable rear \l-ring has; transmitted itself to. the commutator-necks, resulting in so muchbreakagein the commutatorleads that this mounting-construction had to be abandoned. This meant that the dislr spring' and the movable. \l-ring had to be plaeed at the front of the'commutator. where there was n oroom for it, because of the protruding. inner. 1;. rear end 0f he e r g ne ssitat ng en thening of the frame, or a shortening of the core, in order to make room for the disk-spring at the front end of the commutator.

In accordance with my invention, I make the rear V-ring I6 integral with the commutatorspider IS, the front V-ring [8 being movable, and

I place the disk-spring 2| under the immovable rear V-ring l 6, with the top peripheral edge of the disk-spring engaging a rear surface or shoulder of the rear V-ring. I place a pressure-ring with a shoulder in engagement with a rear inner surface or shoulder of the disk-spring 2|, said pressure-ring 25 being movably mounted on'the armature-spider 7, so that it can slide axially in a forward and backward direction. The pressurering 25 is provided with a plurality of forwardly extending studs or elongated tension-members 30, the rear ends of which are firmly secured in the pressure-ring 25, said studs being spaced at uniform intervals around the pressure-ring 25. These studs pass loosely through suitable holes 32 in the commutator-spider l9, and through similar holes 33 in the inner part of the movable front V-ring l8, and the front ends of these studs 30 are threadedly engaged by nuts 35 which are tightened up against a front surface or shoulder of the movable front V-ring 18. The studs 30 are preferably necked down, as shown at 40, at places where they are not threaded, so that the neckeddown diameter of the studs is about equal to the diameter at the bottoms of the threads in the studs, thereby increasing the resilience of the studs.

In operation, it will be apparent that the studs 30 transmit the pressure of the disk-spring 2| to the movable V-ring l8, permitting the diskspring 2| to be placed at the rear, where there is room for it, and permitting the movable V-ring 18 to be at the front of the commutator, so that the immovable V-ring l6 may be at the rear, where it prevents the objectionable axial movement of the commutator-necks I l as the movable V-ring [8 moves in and out, due to temperaturechanges, speed-changes, and spring-pressure ad- Justments.

My invention also overcomes another difficulty that has become so accustomed to, that its avoidance has been looked upon, for all practical purposes, as one of the impossibles. Heretofore, in assembling disk-spring commutators, it has been customary to place the commutator under a press, so as to place the spring under a strain, and then to tighten a retaining-nut for holding the spring in place, in its strained position, I'his procedure was not particularly objectionable in the original assembly of the commutator, before it is assembled in the finished armature, but the necessity for placing the entire armature under a press was not at all desirable, in cases where it was necessary to retighten the commutator in the finished armature. This necessity for the use of a press (not shown) resulted from the fact that the disk-spring of the prior commutators was at the front of the commutator, and was held in place by a large nut which was threaded on the commutator-spider, and which had such a large peripheral friction-surface, in engagement with a front surface of the disk-spring, that it could not be turned when the spring was under stress, as will be apparent from the previously mentioned patents.

In my improved disk-spring mounting, however, the compression of the disk-spring 2! is maintained by a plurality of studs 30, having individual, relatively small, nuts 36 on their front ends, and the peripheral extent of the frictional abutment-surfaces of each of these small nuts 36 is so small that the nuts can be turned when they are pressing tightly against the front surface of the movable front V-ring l8, and an equal stress on all of the studs may be assured by tightening the nuts with a torquewrench (not shown) My new spring-commutator also provides additional resilience or yieldability, because the studs 30 are resilient, in addition to the resilience of the disk-spring 2|. At pressures in common use on spring-commutators, the studs elongate some .015 to .018 inch and the spring deflects some .050 to .060 inch. The additional yield which is provided by the studs 30 thus reduces the difference in the V-ring pressure which is applied to the commutator when the commutatorbars expand or contract due to temperaturechanges or speed-changes.

And the foregoing important operational advantages of my invention are in addition to the still more important space-saving structural advantage that my disk-spring 2| is placed at the rear, where there is room for it, while retaining the use of an immovable rear V-ring which avoids the lead-breakage which heretofore resulted from placing both the movable V-ring and the spring at the rear.

While I have shown my invention in but a single exemplary form of embodiment, I wish it to be understood that various structural changes may be made, by way of substitution of quivalents, and the addition or omission of certain parts, without departing from the essential spirit of the invention. I desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language.

I claim as my invention:

1. A spring-commutator assembly comprising a plurality of commutator-bars having V-grooves in their ends, and having commutator-lead-engaging parts at their rear ends, an immovable commutator-spider having an immovable V-ring at its rear end and an axially movable V-ring at its front end, said V-rings engaging the V- grooves, a disk-spring at the rear end, a peripheral edge of the disk-spring engaging a rear surface of the immovable rear V-ring, a pressurering having a peripheral edge in engagement with a rear inner surface of the disk-spring, a plurality of forwardly extending studs carried by said pressure-ring, and nuts on the front ends of said studs in engagement with a front surface of the movable front V-ring.

2. A dynamoelectric machine having a springcommutator assembly as defined in claim 1, said machine having a stator-frame having a part carrying a bearing which extends close to the stud-nuts, and said machine having a rotormember having a winding and a winding-support having a forwardly extending cylindrical shoulder which provides a space, below it, for the rear end of the rear V-ring and for the diskspring and pressure-ring.

CARL HENRY SUTHERLAND.

N 0 references cited.

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