US2607817A - Brush-holder for electric machines - Google Patents

Description

I 19, 1952 L. PETERLIK 2,607,817

BRUSH-HOLDER FOR ELECTRIC MACHINES Filed April 11. 1950 mmvroze. LEQPOLD PETEQ? m4 Patented Aug. 19, 1952 UNITED c I 2,607,817 In '7 m BRUSH-HOLDER; FOR ELEo'rRIoivrAonmEs Leopold pPe terlik, Vienna, Austria; 'as signor to -Uher *& 00.

Vienna, Austria Gesellschaft fur -Apparateb'au,

{ApplicationApril11, 1950, Serial No. 155,239 I In Austria April 29, 1949 This invention relates to brush-holders "for electric' machines.

"ing' is avoided due to'the' particular construction,

and that in sp'ite of'the fact that the'brushes are'resiliently b'i'a's'sed' towards the side wall of the holder.

'Closely fitting the brushin-the brush-holder has not proved satisfactory. On the other hand a clearance in the holder effects undesirable consequences as vibrations and tilting over of the brush-particularly in case of reaching the critical. number of revolutions, or if the commutator is not exactly circularresulting into'sparking and burning out of the copper segments. In order to overcome the said inconveniences it has already been proposed to bias the brush towards 'theopposite wall of the brush-holder by means of resilient members such as fiat springs, yaws, or the like, which may be disposed in the brushholder or in an opening of the wall of the same. With such constructions special provisions have proved to be necessary inorder to prevent the guide members from failing or tilting, and toensure symmetrical distribution of pressure. Therefore only a rather complicated construction is enabled to ensure sufficient safety of working with the said brush-holders.

With the said constructions, however. considerable frictional forces are involved, thus the brushes are not so easily movable as desired, and even self-stopping may occur.

The said defects may be partly overcome by provision of rollers or ball members rotatably mounted and adapted to transmit the pressure of guiding to the brush. The hitherto known constructions of the art referred to, however, likewise require a considerable constructional expenditure for carrying out the brush-holder and the means for pressure transmitting as well as supporting and guiding of the compression members, such as shown and described for instance in the Letters Patent of the United States No. 662,758 and 2,436,279.

According to the present invention, however, vibrations of the brush are eliminated in a simple way by providing one or more ball members or rollers of steel guided for free rotation, with sufficient clearance symmetrically arranged in holes of one of the walls of the brush-holder, the said holes tapering towards the inner face of the said -wall, and a plate spring fixed to the outer face 7 Claims. (CRIN-324) 2 of the said wa1l,and" bia'ssing'the carbon brush towards the oppositewall oflthe brush-holder. By' these means'the intended elfect'is forwarded in any'respect as by the almost point-like contact in connection with the rolling friction, the unhindered, uniform and ea'sy'feeding of? the brush is ensured even incase 'of'comparatively high pressure of the spring, thus sticking fast 1 and stopping being avoided.

Owing to the said very simpleconstruction the brush is prevented from sticking fast even in" case of the possibly worst soiling, as coal dust or other dust frequently collecting in machines with exhaust fan ,is preventdfromdepositing between the brush and thewall 'kept ina distance' from the brush as war as'between the latter and the guide members, and'that due to the continuously changing positions ofltheballs or rollers.

Some embodiments ofjthe inventionare illus-- trated by way of example" in. the accomp'anying drawing, in which:

s Fig. 1 is a perspective view of the brush-holder according to'the invention, I

"Fig. 2 is a section taken on Iine'II- -II of Fig. 1,

"Figs. 3 and 4 are perspective views of modified constructions of thebrush-holder, and

Figs. 5 and" 6 illustrate modifications of the holder .usi'ng rollers. instead orb'aus.

'Referring to Figs. Land2 the carbon brush 2 is inserted into a box ,I, and is urged *in the direction towards the commutatorby a compression spring not shown in the drawing. Fig. 2 shows that the width of the brush is smaller than the inside width of the box. In the front wall of the box there are provided two conical holes 3 each containing a ball 4 of steel, which balls are forced to the brush 2 by a plate spring 5 fixed to the front wall of the box.

The holes are dimensioned such as to prevent the balls from dropping into the box when still empty. The diameter of the ball sufiiciently exceeds the thickness of the wall, in order to ensure reliably urging the balls to the brush with a sufficient pressure even in case the Width of the brush changes according to the tolerated inaccuracies happening in producing the same. By arranging two balls symmetrically with regard to the longitudinal axis reliable guiding is ensured, and the exertion of equal pressures to the balls is guaranteed by fixing the plate spring symmetrically between the two balls.

In the construction as shown in Fig. 3 there is provided asingle ball disposed in the longitudinal symmetrical axis. Such simple construction has been found sufficient in case of a brush of small 1 3 width, or of a brush the sides of which have nearly equal length.

In the modified construction as illustrated in Fig. 4 there are provided four ball members 4 for guiding the brush, being biassed towards the carbon brush by means of a common plate spring 5 symmetrically fixed-with regard to the positions of the balls. In this examplethe particular construction of the opposite wall of the box may be noted, which may be provided with two or more ribs 6 preferably running in the longitudinal direction and being rounded or flattened.

As shown in Figs. 5 and .6, instead of steel ball members there may be 'used short rollers as has been mentioned already. In such case the holes in the front wall of the boxhave to be rectangular in shape. a

According to the embodiment of the invention illustrated in Fig. 6 the means for guiding by balls or rollers may be applied to the leading and trailing walls, respectively, of the box in regard to the sense of rotation of the machine, the balls being disposed in at least two different planes, perpendicular to the direction of feeding the brush. In this case a plurality of balls is provided in each'of said opposite walls.

Provided the plate spring5 is dimensioned in an adequate way thebrush has proved to be kept in'the holder box so quiet that a satisfactory and sparkless cornmutating is obtained even in case of using coal'brushes of such poor qualities, the use of'which wouldhave hitherto brought aboutseverebreakdowns.

The construction" according to the invention has turned out well particularly in low voltage machines' w'ithcomparatively great current density in the brushes, as well as in small motors a plate spring fastened to the outer face of said front wall, for urging said rotatable members toward an opposite wall of the container.

2. A brush-holder as claimed in claim 1, in which the rotatable members consist of balls.

3. A brush-holder as claimed in claim 1, in which the rotatable members consist of rollers.

4. A brush-holder asclaimed in claim 1, which comprises at least two rotatable members, and in which the plate spring is arranged symmetrically with regard to the rotatable members and acts uniformly on the same.

5. A brush-holder as claimed in claim 1, in which the wall opposite to the front wall, is providedwith' at least two longitudinally extending ribs. 1

6. A brush holder for an electric machine, comprising a container adapted to receive a brush; said container having a front wall and an opposite wall, each provided with a plurality of holes tapering toward the inner face of the respective wall, a rotatable member inserted with clearance inan'd held by each of said holes, a plate spring fastened to the outer face of 'each of said front Wall and opposite wallffor urging said rotatable members toward thejinteriorofthe container, the rotatable members being'arranged in the direction of at least two different planes which are perpendicular to the feed direction of the brush to be fed'by the brush-holder.

7. A brush-holder 'as' claimed in claim 6, in which the rotatable members are arranged in the leading and trailing wall of the container, relative to the direction .of rotation of the ma- LEOPOLD PETERLIK.

EEFERENCESQGITED' The following references are of record'iri th'e file of this patent: l

UNITED STATES PATENTS Number v Name r Date 426,471 Rice Apr. 29, 1890 448,331 Frietsch; Mar. '17, 1891 732,240 Underwood June 30,--1903 2,430,279 Duryee Nov. 4, 1947 FOREIGN PATENTS v j Number 7 Country I -Date 138227 Great Britain' Feb. 5, 1920 447,417

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