US2477766A - Brush mounting for dynamoelectric machines - Google Patents

Description

Aug..2, 1949. c. REINKER 2,477,765

BRUSH MOUNTING FOR DYNAMOELECTRIC MACHINES Filed Sept. 5, 1946 2 Sheets-Sheet 1 I N V EN TOR. Caz/s7 Paw/(2 ATTORNEY Aug. 2, 1949. c. REINKER 2,477,756

BRUSH MOUNTING FOR DYNAMOELECTRIC MACHINES Filed Sept. 5, 1946 2 Sheets-Sheet 2 lrllllm;

INVEVTOR. (Um/5r REM Ire R W D g/ A robe/v25 Patented Aug. 2, 1949 BEUEHDIQUNTING FOR. DYNAMQELECTEIE MACHINES.

Christ Eeinker, hakewood, Ohio Application September 5, 1946, Serial.- No'. 695,010

that in some instances might carry a convex.

contact button, and. with the contact bar or button arranged.- to be resiliently urgedv against the end. of a brush.

lation to the rotor of the machine. and. be. re,-. silientlyurged. against the commutator by suite able spring'contact means. Thus, as the brush wore away, the contactor would still be. urgent against the outer end of the brush to maintain electrical connection therewith and to retain the brush against the commutator. One. dimculty with this present style of brush contacts has been that-the. contacts wear the brush. away unevenly and are apt to cause arcing and undesired, high resistance. at the region. oi contact withthe brush.

The above difficulties of brush contacts. havebeen. increased recently due. to use. of. transversely split brushes in. each brush. holder. resistance to current. flow asv much as. possible, the contactor surface. should bear. on: both parts of such sectional brush simultaneously, contin= uously and, as. nearly as possible, uniformh throughout the. life of. the brush. Usually, some type of shunt wire is connected. between. the parts of the brush to render them operatively in.- tegral for current transmittal.

The. general object of this invention is to avoid,

and overcome the. foregoing and, other disadvantagesv of and objections to, known types of, brush contactors and. to. provide a brush. and contactor or follower therefor. that. are. adapted to provide good electrical contact for their entire service life.

Another object of the invention. is. to. provide floating. type of brush contactor for equaliz .5 brush wear.

A further. object. is to. provide an improved... in=

expensive brush contactor that can easily be r used to replace present standard brush. contactors.

Another object of the inventionis to provide. a brush and a brush. contaotor having substantially complementarily formed. contactin sur- In all events, the brush. would be. mounted for. radial movement with re= To. reduce.

iaces curved. in. the direction of rotation of the motor:

A further object of the invention is to provide a freely movablebrush contactor adapted to maintain uniform contact with. a relatively large amount. of. brush surface regardless. of the mannor in. which the brush wears or becomes cred:- ed by arcing.

Another object. of. the. invention. is to urge the sections of a laminated brush. into. mutual contact and. dispense with hunt. connect-ions be tweenthebrush sections.

The foregoing. and other objects and advan tages oi the. invention. as further explained. below. are. preferably achieved by the. provision of a brush having acylindrically convex outer end, a contact arm, means resiliently urging the corntact arm; towards the: outer end of the brush, and; a contact. block havin a cylindrically concave. surfaoeadapted substantially to mate with the con-vex end of the: brush. the contact block being slidably and. rockably carried. by the con tact arm for floating and. pressure-equalizing engagement with the convexhrushend.

In-the, accompanying drawings;

Fig. 1. is a vertical. sectional. view through. a brush mounting assembly of an. electric motor or generator embodying the. principles of the invention;

2 is a fragmentary vertical section on line 2-2.of. 1.;

Fig... 3 is a: fragmentary View. of an assembly similar. to Fig- 1, showing, partly ciiagraininati cally, the contactor and brushes in. two relative positions, the. contaotor being. slightly modified with-respect to Fig. 1;

Fig. 4r is an. enlarged elevational view similar to: 1 further illustratingv the invention;

Fig, 5 is a. fragmentary side elevation of modified. forms. of contactor and brush respectively, the latter being. partially shown;

Fig. 6 is. a transverse. sectional detail view indicated at 6-5 onFig. 5;

Fig, '7- is. a View similar to Fig. 5, showing a further. modification of. brush. contactor; and

Fig, 8. a sectional detail view thereof as indicatedatfl-Al. on Fig, 7..

Referring further to-the drawings, a conventiona-L commutator i, as in. a direct current electric. motor. has the usual arrangement of parallel conductor bars 2 and insulating spacers 3. The. commutator bars are in sliding contact with the brush. H). which, inthe. particular form shown, is of the. laminated type beingsplit or having individually movable. face=to-face sections II and I2. The radially outwardly facing ends of the brush sections are curved to complement each other in forming a cylindrically convex surface I3. The convexity is in the general direction of rotation of the commutator i, and the convex surface I3 is uniform for the entire width of the brush. The brush unit, as usual, is rectangular in transverse section (not illustrated) i The laminated brush construction in connection with the contactor arrangement hereof may include any suitable number of laminations or brush plates. As suggested inFig. 5, two sections Ila and Ill) are complemented by two sections I2a and I2b to form a multiple plate brush assembly. The pair of sections IIb and I2b have identical curvatures on the top and the pair Na and I2a have identical curvatures but different from those of III) and I212. The contactor enables use of any number of sections without section-connecting shunt wires such as heretofore usually considered necessary in laminated brush assemblies.

The brush sections II and I2 are received in and positioned for radial movement with respect to the commutator I by a housing Id which is rigid with a main hollow metal support or body I5 of bronze or other efiiciently conductive metal. Usually, the body I5 has a plurality of radially extending brush guiding portions M fitting respective brushes which may, for instance, be arranged in pairs laterally spaced apart in edge to edge relation. The supporting body I5 of the brush mounting assembly is carried on the motor frame (not shown) by suitable supporting posts is (one illustrated in Fig. 1), having the usual insulating portion or sleeve H.

The principal feature of the present invention may be wholly embodied in the contactor block or shoe IB which has, on the side facing the commutator, a concave face Isa adapted intimately to mate with the outer convex end of the associated brush or which may be of somewhat wider curvature as illustrated in Fig. 1. The cylindrically concave surface Isa is, of course, positioned in the same direction as the convex surface of the adjacent brush end.

A concomitant feature of the invention is that the contact block or shoe I8 is movably guided and supported with relation to the brush unit I!) in a direction tangentially of the rotor and its commutator, and preferably additional limited movement of the contact block is provided. The contact block or shoe I8 is supported on the usual flat sheet metal contact arm ZI, which is provided with suitable resilient means, to be later described, urging it toward the commutator.

For supporting the contact block against the brush unit, as shown particularly by Figs. 1 and 2, the contact block has upwardly and inwardly turned flanges I9 at its opposite sides, thus formin a partially closed channel 20 on the top face of the block which slidably receives the contactor arm 2 I. The channel is of such proportions with relation to the cross section of the contact arm that its walls loosely engage the arm and enable the contact block to rock such slight amount as may be necessary to compensate for unevenness of brush end surface or, as illustrated by Fig. 4, to compensate for wearing away of one brush section II or I2 faster than an adjacent brush section wears. Very little rocking or universal movement is necessary for that purpose since the brush sections tend to wear evenly.

In Fig. 4, the contact block Ill has rocked slightly clockwise on the contact arms 2| in compensating for the lowered position of the top curved end of the brush section II relative to the top end of the section I2. This rocking movement maintains adequate pressure and conductive contact between the concave and convex faces of the contact block and brush, as the brush sections wear away.

For adjusting contact pressure between the contact block and the brush, the contact arm 2! is carried on a pair of parallel pivot plates 22 (one shown) which, in turn, are mounted for free turning movement on a cross pin 23 suitably carried in the side walls of the body I5. A spiral spring 24 is connected to the body at one end as by rivets 24c (one shown), and to the contact arm assembly as through a sleeve 25. The sleeve is turnably mounted in the ears 22 and one end of the sleeve rigidly carries a ratchet wheel 26. The spring tends to turn the ratchet wheel counter-clockwise and the spring force is transmitted to the arm 2! through one of its mounting ears by reason of a pawl 21 pivotally carried as on a pin 28 bridging the two mounting cars 22. The spring force may be adjusted by releasing the pawl and turning the ratchet wheel clockwise or counter-clockwise for increase or decrease of brush contact pressure.

Usually in the type of brush mounting assembly illustrated, the contact arm 2 I has a flexible shunt connection with some electrically conductive part of the body I5. One improvement represented by the present arrangement is the provision of such shunt connection directly with the contact block or shoe I8. As shown, a flexible metal conductor ribbon or strap, for example braided wire 38, is fixed to a rearwardly extending projection 3i of the block, fastened in place as by riveting or brazing.

The preferred manner of fastening the shunt wire to the block I8 is as shown in Fig. 4, wherein a rivet 30a fastens the wire against the under face of the projection 3 I. This avoids the expense of slotting the projection as illustrated in Figs. 1 and 3.

The flexible shunt connector strap to preferably extends from the contact block rearwardly loosely around the cross pin 28 and then loops forwardly for connection to thebody I5. The end of the strap remote from the contact block may, for example, be secured as at 32 by the same rivets Zea as secure the fixed end of the spiral spring 2 3.

In order to limit the sliding movement of the contact block along the contactor arm 2!, the free end of the contactor arm may be turned downwardly to form an abutment flange as for preventing the contact block from being moved further than desired outwardly along the contact arm. Additionally, to limit the movement of the block toward the pivotal support of the contact arm, a pin such as 35 may be provided on the contact arm. The limiting abutments are spaced apart wide enough so that the contact block is free to travel whatever distance it has to along the contact arm in order to remain in contact with the brush unit as it becomes worn. Note that in Fig. 3 the contact block it in the fullline-illustrated position is closer to the limiting abutment 35 than in the initial position of the contact block shown in broken lines and corresponding to the arm and block position of Fig. 1. The usual lifter arm 36 for the contact arm assembly overhangs the contact block in spaced relation thereto and serves as a guard. The usual electrical feeder connection (not shown) is secured to the body l5 by the nut and screw assembly 31.

It is not necessary that the concave face of the contact block be continuous. As shown in Fig. 3, a relief groove 38 divides the brush contacting surfaces into separate portions as at IBb and I80. Fig. 3 further shows that the mutually contacting surfaces of the brush and contact block truly are complementary. It is only necessary for practical accomplishment of the objects hereof that the curved contacting surfaces of brush and contact block substantially mate.

Referring to Fig. 5, the contactor as there illustrated is in two parts, both capable of being made as stampings from metal best suited to the respective parts. The stamping 38 (i. e. copper or bronze) corresponds to the block l8, having a hemi-cylindrical portion 40 for embracing the brush and a flat extension 4| to which a shank portion of the sheet metal part 42 in the form of a clip is secured as by rivets 43. The clip may be of a metal chosen for strength rather than electrical conductivity. The forward end of the shunt wire 30 is clamped between the rivet-secured parts. The clip 42 extends upwardly from the extension 41 over the hemi-cylindrical portion 40 of the contactor part 38 and is there formed into a channeled guide having a base 44, against which the pressure arm 2| bears, and mutually inwardly extending flanges 45 completing a guiding trough for said pressure arm. There is suflicient clearance between the flanges and base so that the contactor assembly can rock as necessary in the manner suggested in Fig. 4, previously described.

In the form shown in Fig. 7, the contactor member 38 supports on its top side and has secured thereto as by the rivets 43 a sheet metal clip 50, the unattached end portion 5| of which is bent upwardly and has a through opening 52 for receiving the pressure arm 2|. Again the opening 52 has adequate clearance to enable rocking of the contactor assembly 38-50 through the required limits.

The operation of the arrangement according to Figs. 5 to 8 inclusive is substantially the same as already described in connection with Figs. 1 to 4 inclusive.

From the foregoing, it will be apparent that substantially complementary curved surfaces are formed on the contact shoe and brush unit so that the shoe is free to float, as required, in order to maintain proper electrical contact and adequate radial pressure forces on the end surfaces of the brush. Also, the concave faces [8a, 1% or I of the shoe will urge the laminated sections of the brush together when a sectional brush is used. The more intimate contact between the brush sections avoids the necessity for pig-tail shunt connections between the brush sections as now extensively used.

I claim:

1. In a brush construction for a dynamo-electrio machine having a brush with a convex outer end portion, a contactor member having a concave portion generally complementary to the brush and an arm portion extending therefrom, a sheet metal clip secured to said arm and extending above the concave portion, said clip having an opening through it adapted to receive a pressure arm for holding the concave portion against the brush.

2. The contactor device according to claim 1, wherein a shunt Wire is secured between the contactor member and the clip.

3. The contactor device according to claim 1, wherein the clip has an upstanding free end portion with a generally rectangular opening formed therethrough to receive the pressure arm in edgewise contact with the sheet metal of which the clip is formed.

CHRIST REINKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 717,656 Beeler Jan. 6, 1903 1,277,394 Dean Sept. 3, 1918 1,363,722 Dean Dec. 28, 1920 1,936,422 Durnham Nov. 21, 1933

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