US1721515A

US1721515A - Commutator

Info

Publication number: US1721515A
Application number: US250603A
Authority: US
Inventors: Kroehle Ralph
Original assignee: Individual
Current assignee: Individual
Priority date: 1928-01-30
Filing date: 1928-01-30
Publication date: 1929-07-23
Anticipated expiration: 1946-07-23

Description

July 23, 1929. KRQEHLE 1,721,515

' I COMMUTATOR Filed Jan. :50, 1928 Patented July 23, 1929.

UNITED STATES RALPH KROEHLE, O F WARREN OHIO.

COMMUTATOR.

I Application filed January 30,'1928. Serial No. 250,603.

V This invention relates to commuta'tors and to a method of making the same. It has become highly desirable to use molded commutators for electric motors, especially motors of the smaller horse power type. It is essential that such commutators possess high insulating properties and will withstand the heat generated in service as well as being capable of maintaining their integrity of construction under all conditions of use. Various attempts have been made heretofore in the art to provide molded commutators. using plastic setting materials, but these have not proved satisfactory, asthey disintegrate under the bursting strain to which the commutators are subjected in service. In other types of plastic material bodies there is an objectionable feature that the body is softened under heat permitting the commutator segments to become loosened and thus destroy the effectiveness ofv the structure. 7

, Objects of my invention are to provide an improved molded commutator whereinthe material ofthe body is of a metallic nature; to provide a commutator formed with a body of metal in which the commutator segments are secured; and to provide a method of constructing such commutators.

With these and such other objects in view as will be apparent from the description, the invention resides in the novel construction, combination, and arrangement of parts as well as the method hereinafter described and claimed and illustrated in the accompanying drawingswhereof Figure 1 is an end elevation of a vertical type commutator as mounted .on an armature shaft. r

" Figure 2 is a vertical section therethrough on the line 22 of Figure 1.- 1 Figure -3 is a rear face elevation of one of the commutator segments employed.

Figure 4; is an end elevation of a horizontal type commutator as mounted on an armature shaft. 4 v

Figure 5 is a vertical section taken there through. In detail, the vertical'type commutators comprise an annular series of commutator segment bars 5, of copper or other-suitable metal, having vertically plane outer faces for brush contact with the brushes 6 and 7, the segments being spaced apart by strips. of mica or other suitable insulating members 8. The body of the commutator to which these segments and insulating members are attached in the disclosed embodiment consists of a molded body 9 of type metal, this material being best adapted for the purposes of the invention and being the preferred material employed in the formation of the bodies. The rear face of each commutator segment is formed with an undercut recess 10 for receiving a corresponding head 11 eX- tending from the body 9 when the metal is cast into the/recesses, thus providing a rigid connection between the commutator segments and the body. Interposed between the body 9 and-the rear face of eachcommutator bar is an insulating shield 12 formed-of any suitable material such as asbestos, baked on enamel, or varnish, or any suitable insulating medium which is applied as a coating-or backing sheet to the inner faces of the commutator segments before the body 9 is'molded or cast in place. Suitable means are provided in the type metal body tions embedded in the body 16, which is, of

course, formed of molded type metaL In this form of the invention the

contact brushes

16 and 17 engage horizontally against the outer contact' faces of the commutator bars. As in the vertical type, the commutator segments 15 are arranged in an annular series being spaced apart by insulating members, comprising mica strips 18 and the outer contact surface of each segment is raised slightly above the outer peripheral face of the type metal body 16 as best shown in Figure 5. Each of the commutator bars 15 is undercut at each end to form a recess and to provide an anchor head 19 which is material whichis adapted for the purpose nated. Type lnetal has the peculiar characand may be formed of asbestos, enamel, or varnish, etc., so long as it. possesses the requisite insulating properties.

In both types of commutator, the insu-. lating members which are disposed between the series of segments are of co-extensive area with the segments and are of identical.

configuration so that the segments and insulating strips are positioned side by side to form. uneven surface at their inner faces for reception of the backing sheet of insulating material 12 or 20 as thc'case may be. This arrangement may be varied as desired.

The method of constructing these commutators is carried out by properly assenibling the commutator segn'ients and their interposed insulating strips in a jig and tightening the same in position. :backing 12, or 20 asthe case may be, is then 'applied over the inner faces of the assem- The insulating bled segments and insulating strips, care being taken to see that it entirely'covers every portion of the commutator segments and insula ting strips which are to be embedded or in contact with. the body of type metal. After this insulating backing has been applied, a suflicientquantity of melted type metal ispoured or cast into the form and in the process of molding the metal will, of course, flow; into the recesses i'ornied by'under-cutt-ingthe inner portions of the respec tive segment bars, thus filling all the recesses and engaging around-the anchoring tongues whereby When the metal body-1s cooled and hardened,-the COll'ilHllliltOl segments will'be .firmly embedded in the type metal body.

The fastening element 13, shown in Figure 2, may be positioned inthe at the time th commutator segments are assembled and before pouring of the type metal body. 7 The resulting structureproduces an extremely durable, strong, rigid commutator having a body of metal which is capable of resisting any bursting strain to whici the commutatortmay be subjected. -Any developed heat tends to distribute substantially uniformly over the entire body of thecommutator and the metalfwill not soften. The commutator segments are held rigidly in position and any disalignment or relative dislocation therebetweenis absolutely elimiteristic of expanding slightly upon cooling so that the metal is forcedby internal pressure in the molecular structure of the metal itselffinto eil'ective engagement'within the recesses formed in the embedded portions of the segment bars.

In compliance with statute, I have described one complete embodiment as using type metal, but I may equally well employ any alloy, metal or suitable material which will fulfill the purposes of the invention.

, WVhile I have illustrated and described in this form of the invention the best means I have thus far devised for carrying it into etlect, I (.leire it to be understood that the invention is not limited thereby, but that any desired changes and modifications may be-inade in the structuraldetail as will fall within the scope of the invention as claimed.

I claim:

1. A commutator comprising commutator bars embedded in a body of metal molded thereon and insulated ,theretroni.

2. A commutator comprising metalcommntator bars insulated and embedded in a body of type metal molded thereovc'r. i "3. A. commutator having a molded body of typemctal; 4.' A commutator comprising connnutator bars spaced apart by insulating members, an insulating backing over said bars and spacing-'n'ienibers, and a body of metal molded .around portions of said bars for anchoring said bars to the body. 5. The method of making a commutator, "which; consists in embedding comn'iutator bars having an applied insulating material thereon, in a body of molten metal and cooling the metal to'lorm the connnutator. (5. The method of making a con'imutator, which consists in arranging commutator bars circumfcrentially with interposed insulating strips between the respective bars, 'applying an insulating covering over the inner portions of said bars and insulating members, and pouring molten metal into the interior ofthe assembled structure to form a body-on coolin m ALPH; KROEHLE.