US1274411A - Commutator and the method of manufacturing the same. - Google Patents

Description

E. A. HALBLEIB & T. L. LEE.

COMMUTATOR AND THE METHOD OF MANUFACTURING THE SAME. APPLICATION FILED JUNE 26.1915.

1 ,274,4 1 1 v Patentea Aug. 6, 1918.

lllrnvcelmmrsz I Dam/4 8* mutator in which the UNITED STATES PATENT OFFICE.

DWARD A. HALIBLEIIB AND THOMAS L. LEE, or ROcHEsTER, NEW YORK, AssIGnoRs To NORTH EAST ELECTRIC COMPANY, OF ROCHESTER, NEW YORK, AOORPO ATION or NEW YORK.

COMMUTATOR AND THE METHOD OF MANUFACTURING TI EE SAME.

Specification of Letters Patent.

- Application filed June 26, 1915. Serial no. 36,519.

To all whom it may concern:

Be it known that we, EDWARD A. HAmLEre and THOMAS L. LEE, citizens of the United States, and residents of Rochester, in the county of Monroe and State of New York, have invented certain new and useful Improvements in Commutators and the Meth ods of Manufacturing the Same, of which the following is a specification.

This invention relates to improvements in the structure and the manufacture of the commutators of electric motors, generators, or other machines.

A commutator, as ordinarily constructed, comprises a series of conductive bars which are mounted, with interposed insulatin material, around" a shaft, the bars eing clamped in place by collars fixed on the shaft and cojiperating with the ends of the bars, while insulating material is interposed between the bars and the collars, and usually between thebars and the shaft also, to prevent short-circuits between the bars. The mechanical strength of a commutator so constructed depends upon the accuracy and firmness with which the bars are seated against the insulating material by which they are held in place and separated from each other, and the object of the present invention is to facilitate the manufacture of such commutators, and to produce a combars are, in every instance, securely held against accidental displacement both in the course of manufacture and 'n the subsequent use of the commutator. I

It is common, in the manufacture of a' commutator, to provide outwardly-directed,

and usually inclined, bearing-surfaces at the ends of the commutator-bars which 7 co-- operate, through the intermediation of thin bushings of mica or other insulating material, with. the clamping-collars. ,When thesecollars are screwed up, to engage the bars fir1 t ily,'= the bars are all forced inwardly, that', i s,. toward the axis of the shaft, so as to compress the insulating material interpos'edRbetween the adlacent bars, this material consisting usually: of mica, wholly or in part. Where the bars are provided only with outwardly-directed bearing-surfaces, as just described, security against inward displacement of any one of the bars, as a result of an accidental blow or any other extreme accuracy cause, is afforded only by the pressure, against the slightly converging faces of the bar, exerted by the insulating material which is interposed between the ad jacent bars, Since this material isiusually more or less compressible, especially when heated, as it may be either in use or in the Patented Aug. 6, 1918. I

lateral surcourse of manufacture, sufficiently tosoften such cement as may constitute a part of the insulating material, it has been found in practice that in the arrangement just described the support against such 'inward displacement of the bars is not alwayssufficient. In some cases, accordingly, the commutator-bars have been provided, in addition, with inwardly-directed bearing-sing faces, either at their ends, or extending from one end to the other, these inwardly-directs Y bearing-surfaces being forced into engagement with insulating material interposed between the bearing-surfaces and either the clamping-collars or the shaft. While such an arrangement, when carefully and accurately constructed, afl'ords adequate support-f0r the bars, it is diflicult to construct a commutator in this manner with such accuracy that all of the several parts of the insulating material shall be brought simultaneously to the proper degree of compression. That is to say,

ably compress the insulating material'between them, they shall also have been it is diflicult to insure that, in the exact position in which the bars have been moved inwardly enough to suitbrought to a firm seat against the insulating material engaging both their inwardlyrdirected and their outwardly-directed bearingsurfaces.

In accordance with the present invention the commutatorrbars are provided with bearing-surfaces both inwardly directed and outwardly directed, and insulatingimaterial is arranged to engage both of these surfaces, but in order to eliminate the necessityfor in the bars and in the thickness of the insulatingbushinggginsulab s mat r of d fislse t' c a cter s i s is employed}: tdifl'erent p'oints in the structure. Inthe prefer-red embodiment of the invention the material directed bearing-surfaces may be comparatively firm and unyielding in character, and its thickness need not be gaged with extreme accuracy, because the material engaging the engaging the outwardlyinwardly-directed bearing-surfaces has originally a comparatively yielding character. Accordingly, when the clamping-collars are forced against the ends of the commutator the bars are positioned with reference to their outwardlydirected bearing-. surfaces and to the compression of the insulating material interposed between the bars, while the ed against inward movement, as well asagainst movement outwardly or in an endwise direction.

The material which we have found to be best adapted for the purposein question is a composition consisting either wholly or in part of a phenolic resin such, for example, as one of the well known phenol-condensation products. This synthetic resin may be compounded with more or less paper-fiber, or other material of permanent characteristics, but the composition as a whole possesses to a substantial degree the characteristics of the resinous material, that its hardness and rigidity depends upon the degree to which it has been cured or seasoned by heat. Accordingly, the material which engages the inwardly-directed bearing-surfaces is only partially cured prior to the assembling of the elements of the commutator, so that it has still the capacity to yield when subjected to a moderate degree of pressure. After the commutator has been assembled, however, the partly cured material is completely cured by subjecting the assembled commutator to. heat, thus preventing further yielding of the material, and securing the bars against movement in any direction; In the accompanying drawings: Figure 1 is a-longitudinal sectional view of a commutator constructedin accordance with the present invention;

Fig. 2 is a section on the line2-2 in Fig.

-1, looking from right to left in the latter figure; I

Fig. 8 is a perspective view of one of the insulatin bushings which engages the outwardly-dlrected bearing-surfaces of the com- I mutator-bars; and; r

Fig. 4 is a perspectiveiview of one of the bushings ,which .engage the inwardly-directed bearing suiffaces on thebars.

In the illustrated commutator the central shaft-5, which may. be. the armature-shaft of an electric generator or motor, is surrounded in the usual mannerby commute? tor-bars 6,of copper orother conduct vejmaterial, and each ofthese bars 1s provlded, at

'plished I subjected to no its ends, with outwardly-directed bearingsurfaces 8, which are preferably machined to constitute elements of a conical surface in the usual manner. The shaft is also provided with the usual clamping- collars 9 and 10, the collar 10 being movablealong the shaft by means of a nut 11.

' Thin strips of insulating material are interposed between the adjacent bars, as shown in Fig. 2, and a bushing 12 of conical form is interposed between the clampingcollar andthe bearing-surface 7 in the usual.-

manner'. This bushing 12 may be formed of any ordinary or suitable insulating ma terial of a comparatively unyielding character. It may, in fact, be formed of. a composition characterized by the presence of a phenolic resin, provided this. resin be com pletely cured 'so as'to be firm and The present invention resides particularly in the use'of bushings 13 interposed between the bearing-surfaces 8 and the shaft 5. These bushings are formed, as above described, of composition including partially cured ma u i dterial. When the parts of the illustrated commutator are assembled, the bushings 13 are forced, in the manner of wedges, into the angular spaces between the ends of the bars ressed against.

however, the

and the shaft 5, and are thus the bars. At'the same time, bushings 12 force the .bars inwardly, and

since these bushings are comparatively unyielding, the final position of the bars is determined by the pressure of the bushings 12-, as opposed by the resistance-to compression of the insulating-material interposed between the-bars, and atthis time, accordingly, the bushings 13 yield and flow suf-- ficiently to accommodate themselves to the inward movements of the bars.- The sur lus material of the bushings l'3 may flow intov the space between the bars and the shaft beyond the bearing-surfaces 8, 'suflicient space being left for this purpose, although.

a sleeve 14 of insulating-material may be ness as to-interfere wit described.

a After the commutator has baa-esteemedas" just described it remains only to heat the of the heat which occurs in the commutator when itis in use.

and prevent" any further yielding.

' interposed'between the bars andthe shaft, provided it is not of such-length. or thickthe movements jus't or the commutator may be for express-.purpose'of curing the ins latheating operation, however,'-

A further advantage which we have found particularly in the use of insulating ma terial comprising a phenolic resin, residesin the fact that when this material is heated and cured, as above described, it expands slightly, this expansion. being permanent and not merely the temporary result of the rise in temperature. This expansion forces the material into any slight irregularities j in the bearing-surfaces of the bars, and into the spaces between the adjacent bars, and it also increases the outward pressure against the bars, so that the structure is rendered very firm and rigid. g

While the material particularly described is the best which has yet been found for the purpose in question, it will be apparent that other materials may be employed which are.

capable of yielding when the commutator is assembled, and of being subsequently hardened either by the action of heat or otherwise, and accordingly the invention is not limited to the particular materials described, or to the particular form of the parts of the commutator, or to the use of heat for the purpose of hardening the insulating material. I

.We claim:

1. The method of making commutators which consists in clamping commutator-bars against a body of yieldin insulating matethem into said body and then heating the commutator to harden said substance.-

4. The methodof making commutators which consists in clamping commutator-bars against a bod of insulating material containing a artlally cured phenolic resin, and then" heatmg the commutator to cure the resin. z

5.. A commutator, comprising commutator-bars with inwardly and outwardly directed bearing-surfaces at their ends; clamping and supporting means for the bars; and insulating material interposed between said means and said bearing-surfaces, the insu- $0" .lating material engaging the inwardly-directed surfaces being comparatively yielding so as to permit the position of the bars to be determined with reference to the out 1 wardly-directed surfaces.

6. A commutator comprising I commutator-bars with inwardly and outwardly inclined bearing-surfaces at their ends; a shaft; clamping-collars on the shaft; com-p paratively-thin and rigid bushings, of insulating material, interposed between the collars and the outwardly-inclined bearingsurfaces; and conical bushings, of comparatively yielding insulating material, inter-- posed between the inwardly-inclined bearing-surfaces and the shaft.

7. The method of making a commutator comprising a rigid core, commutator-bars,

and end-members, which method consists in clamping the bars between the end-members and around the core, with a bodyvof yielding insulating-material interposed between the bars and the core, and then subjecting said material to a hardening treatment.

8. The method of making a commutator comprising a rigid core, commutator-bars, and end-members, which method consists in clamping the bars between the end-members and around the core, with a body of insulating material, comprising incompletely cured phenolic resin, interposedbetween the bars and the'core, andthen completing the curing of said resin by theagency of heat.

- EDWARD A. HALBLEIB.

THOMA S L. LEE.

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