US2357111A

US2357111A - Commutator

Info

Publication number: US2357111A
Application number: US467959A
Authority: US
Inventors: Lawrence F Hemphill
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1942-12-05
Filing date: 1942-12-05
Publication date: 1944-08-29
Anticipated expiration: 1961-08-29

Description

1944- L. F. HEMPHILL. 2,357,111

COMMUTATOR Filed Dec. 5, 1942 Inventor: Lawrence F. Hemphill,

/V H Hi e attorney Patented Aug. 29, 1944 COMMUTATOR Lawrence F. Hernphill, Fort Wayne, Ind., assignor to General Electric Company, a corporation of New York Application December 5, 19, Serial No. 467,959

3 Claims.

My invention relates to commutators for dynamo-electric machines.

An object of my invention is to provide improved and simplified commutator constructions.

Further objects and advantages of my invention will become apparent and my invention will be better understood from the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In the drawing, Fig. 1 is a side elevational view. partly broken away, illustrating an embodiment of my invention; and Fig. 2 is a perspective view of the insulating support shown in Fig. 1.

Referring to the drawing, I have shown an embodiment of my improved commutator wherein an insulating sleeve supporting element I is mounted on a shaft H and is formed with a plurality of axially extending grooves I! which extend from adjacent the outer end of the sleeve l0 inwardly of the support and in an outer angularly extending surface I! of an outwardly extending insulating shoulder element ll. The shoulder I4 is formed at an angle to the axially extending sleeve portion l0 and stops I! are formed at the end of each of the slots l2 at the end of the insulating support opposite the shoulder II. The commutator is formed of a plurality of segments of electrically conductive material which include axially extending brush seat portions it and angularly extending portions H which are arranged in the portions of the slots I! in the sleeve Ill and the shoulder ll, respectively. A clamping ring I! of insulating material is arranged over the commutator segments and is pressed over the axially extending portions thereof to a position adjacent the shoulder I4 and biases the segments into engagement with the insulating support for retaining the commutator in assembled relationship. With such a construction, centrifugal force will act on the angularly and axially extending portions of each commutator segment, as indicated by the arrows a and b, repsectively. Since the angular segment portion extends outwardly from the axial segment portion, the radius c at which centrifugal force acts on the angular portion is greater than the radius d for the axial portion. Therefore, if the weight of the angular portion is substantially the same or greater than the weight of the axial portion, the centrifugal force acting on the angular segment portion on rotation of the commutator will be greater than the centrifugal force acting on the respective segment axial portion. The two portions of each commutator bar may be formed of such a size that the weights thereof are substantially the same, butthis is not essential. The radius 0 of the center of gravity or the hypothetical point of action of centrifugal force on the segment angular portion is substantially greater than the radius d of the center of gravity or point of action of centrifugal force on the segment axial portion, and, therefore, the centrifugal force a on the segment angular portion will tend to be greater than the centrifugal force b on the segment axial portion. A consideration of force moments due to centrifugal force on the segment portions indicates that a force moment acts on each of the segments it about the clamping ring is as a pivotal retainingring. On rotation of the commutator. the segment angular portion I1 is acted on by the centrifugal force a acting through a moment arm e and the segment axial portion is acted on by the centrifugal force b acting through a moment arm f. This produces a centrifugal force moment ae for the segment angular portion and a centrifugal force moment bf for the segment axial portion. In order to assist in maintaining the axial segment portions firmly against the insulating supporting sleeve ID, the segment angular portions on one side of the retaining ring are constructed of such a size and arranged to extend at such an angle that the centrifugal force moment ae thereon about the clamping ring ll is greater than the centrifugal force moment bl on the segment brush seat axial portion, thereby tending to rotate the segment about the ring IS in a counterclockwise direction as viewed in Fig. 1. Thus, centrifugal force will tend to hold the commutator in assembled relationship rather than tending to cause it to fly apart.

While I have illustrated and described a particular embodiment of my invention, modifications thereof will occur to those skilled in the art. I desire it to be understood, therefore, that my invention is not to be limited to the particular arrangement disclosed,.and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A commutator including an insulating support. a plurality of commutator segments arranged on said support, and pivotal retaining means arranged intermediate the ends of said segments providing a brush seat portion and a portion on the other side of said retaining means for securing said segments on said support, the weight and center 0! gravity of said other side segment portions being such relative to that of said brush seat segment portions that the moment oi said other side portions about said securing means is greater than the moment oi said brush seat portions thereabout.

2. A commutator including an insulating support having a shoulder thereon extending outwardly at an angle, a plurality of commutator segments having a portion of each extending axially on said support and a portion of each iormed at an angle to said axially extending portion, and means for securing said segments on said support with said segment angular portions clamped against said shoulder. the weight and center of gravity of said segment angular portions being located such that the moment thereof about said securing means is greater than the moment 01 said axially extending segment portions thereabout.

3. A commutator including an insulating sleeve assmn support having a shoulder thereon extending outwardlyatananglaapluralityoispaeedapart grooves in said sleeve and shoulder. a plurality oi commutator segments having a poruon oi eachextendingsubatantiallyaxiallyinsaidsieeve grooves and a portion 0! each formed at an angle to said axially extending portion. and means including a clamping ring arranged over said segments adjacent said shoulder for securing said segments in said grooves on said supporting sleeve with said segment angular portions clamped against said grooves in said shoulder. the weight and center of gravity of said segment angular portions being such relative to the weight and center of gravity 0! said axially extending portions that the moment of said anaularly extending portions about said clamping ring is greater than the moment of said axially extending segment portions thereahout on rotation 01 said commutator.