US2421795A - Armature brush - Google Patents

Description

June l0, 1947.

F. G. MAJER ARMATURE BRUSH Filed Feb. 8, 1945 w/ /'/i/1j e? Se@ Je ik? 94 De @y f i;

Patented June l0, 1947 ARMATURE BRUSH Frank G. Major, Berwyn, Ill., assigner to International Harvester Company, a corporation of New Jersey Application February 8, 1945, Serial No. 576,809

2 Claims. l

This invention has to do with electrical conductor brushes of the type used in conjunction with slip rings or commutators upon the rotatable armature of dynamo-electric machines, and the general object of the invention is the provision of brush components presenting a novel shaped armature contacting surface particularly adapted to retain its uniformity of contact with the armature.

Conventional brushes of the present class have a dimension between the leading and trailing edges thereof, or oircumferentially of the armature, that is a compromise between a short dimension which tolerates partial dropping of the brush into low areas oi a worn amature or a longer dimension which sometimes causes the brush to be cocked by the transverse force applied thereto by the rotating armature. Either of' these conditions is undesirable for each causes sparking to occur between the brush and armature. Making the brush thin by decreasing the dimension between the leading and trailing edges to diminish the likelihood of cooking increases the tendency of the brush to bump against the edges of pits and the like which more frequently develop on commutators where the commutator bars and the insulation therebetween wear away unevenly. Thickening the brush by increasing the distance between the brush leading and trailing edges to avoid the disadvantages of the thin brush, incuirs the above mentioned tendency to cock. In small dynamo-electric machines an acute problem has existed because the dimension range for a brush sumciently thin to avoid the cooking contingency borders on or overlaps the dimension range wherein the brush is so thin as to ride irregularly over a worn surface complemental thereto on the armature. Under these circumstances the thickness of the brush between its leading and trailing edges becomes undesireably critical or even reaches a stage where it is impossible to select a thickness avoiding both of the undesired conditions.

a more specific object of the invention is the provision of a novel brush employing a thin jpianar formation having an end surface for contacting the cooperative current conducting surface of the armature while extending axially thereof, together with rib-like formation means projecting transversely of said planar formation, and such rib-like formation means reaching to the end of the brush which contacts the armature for preventing the armature contacting surface on the planar formation from bumping against the edges of armature surface depressions while Figure 2 is a, transverse sectional view taken on the line 2--2 oi.' Figure 1.

With continued reference to the drawings, the brush Il is shown in conjunction with an armature commutator I2 of which only a few oi' the commutator bars i3 are shown in full iines. These commutator bars are isolated electricaly from one another by the usual intervening layers i4 of insulating material. A conducting periphery of the armature for being borne against by the brush H in current conducting relation there with is formed by the radial outer peripheries of the commutator bars I3.

The upper end portion i5 of the brush. con stitutes a holding portion which is adapted to ne anchored in a brush holder device not shown. .A groove I6 Within the holder end portion i5 r cooperating with a brush holder instrumentation in the manner well known in the art.

The brush il may be formed conventionally' by being molded into shape from minute carbon particles or such particles having metallic per ticles mixed therewith. Regarding the hi with reference to the direction of rotation armature with respect thereto, as indicated 5 the arrow in Figure l, such. brush has e, read 'ig face I'l, a trailing face i8 and opposite :denk sur-n faces l9 and 2|. Two cavities 22 and 23 are formed in the lower end portion. Friese cavities are formed at the intersections of the :dank faces i9 and 2l 'with the leading face il oi brush and extend lengthwise of the brush completely to the lower end 'thereofc Said. cavities are also spaced from one another laterally of the brush to leave a rib-like formation Fifi?? tiiereietween. This rib-like formation 24 registers with a median line a (Figure 2). It is apparent in Figure 2 that the cavities 22 and 23 leave a planar formation 25 at the trailing face in the lower end This planar portion of the brush structure.

formation the formation 24 projecting later- 1. An electric current conducting brush comally therefrom may be likened to intersecting prising a holder end DOrtion and an opposite end freenoled ribs. The free ends of the ri'o 25 are portion for engaging an electrical conductor pethcportions shot i roost remotely from the line riphery of an electrical machine armature during fsf-:1, in Fig. 2 n e the free end of me rib 24 n relative movement between the brush and armais et the edge The ower ends of the ribs or ture in the direction of a. median line directed formations ii and 25 hear complementransversely 0f the brush. the opposite end porhtelly upon the armature periphery in current tiOn Of Said brush including a relative thin conducting relation therewith and stabil the detritable electrical conductor rib-like formation brush structure with respect thereto. e DXOJECHS endWSe 0f the brush from the holder ing the brush structure with reference to the end POltiOn and dSDOSed tl'nSVBl'Sely 0f said assumed direction of rotation of the armature, median line, Said Opposite end portion also inthe leading edge of the armature-engaging face cluding a single detritable electrical conductor e l and or' such brush structure has one rib diSDOSBd transversely of said rib-like formation in registry with said median line and extending lengthwise of the brush from its holder end portion, and said rib-like formation and said rib having free-ended faces at the opposite end of .nd adapted to bear complementally on forward oi? the ci i. edge of the armature engaging trailing fece of the formation 25.

of the armature-engaging fece upon the rib 2li et 5J fe Dtphel'y 1n Current Conductinl the lower end of the brush constitutes :i fe Yef'on wmlended mea of Wncn the free and s at me 2. An electrical conductor brush structure havg@ ing a holder eno, an opposite end for engaging of me Mb M t@ extend the an electrical conductor periphery of an electrical ce the brush a Sumciem 25 machine amature, oppositely disposed leading my f @he Mmmm@ my andtrailing faces extending lengthwise of the ,l www over @he r, structure and oppositely disposed flank surfaces leading edge Of extending lengthwise of the structure and reachd Striking the ing between the leading and trailing faces, and

mmm the 30 said structure containing cavities at the inters wom in use, sections of said surfaces with one of said faces, said cavities being spaced from the holder end of the structure while communicating with the opposite end thereof and being spaced from one median une, D v I in 3 5 another transversely of the one face to leave a b blush s fabricated is rib formation therebetween having a free edge entry rapidly at the extending lengthwise of the structure to the armature periphezy engaging end thereof.

FRANK G. MAJEH. cools. by the force 40 m muy of and by r0 .i-aFERENCES CITED e i90 @w55 im brush face t0 The following; references are of record in the und prevent cooking. g1@ 0f @his patent;

engaging su.

or-muy rr o A,he armature ).iomber Name Date 1,352,408 Hood Sept. 7. 1920 FOREIGN PATENTS 50 Number Country Date 240,518 Germany Nov. 11, 1911 138,450 Germany Jan. 31, 1903

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