US1761066A - Brush holder for dynamos - Google Patents

Description

June 3, 193,0. T, s BINDSCHEDLER ET AL 1,761,066

kINVENTOR BRUSH HOLDER FOR DYNAMOS Filed OCT.. 4, 1924 EIWI- mi! lill/- j Nm J 1 M Mw www ATTORNEY Patented 4June 3, 1.936`

UNITED STATES,

PATENT OFFICE THEODORE AS. BINDSCHEDLER, OF DETROIT, AND PETER J'. ROSTER, OF PLEASANT RIDGE, MICHIGAN, ASSIGNORS TO BURROUGHS ADDING MACHINE COMPANY, A A

CORPORATION 0F MICHIGAN BRUSH HOLDER Foa DYNAM'os l Application led '0ctober 4, .1924. Serial No. 741,758.

This invention relates to a brush holder for electric motors and the like and its urpose is to provide an improved holder w ich is adjustable for the purpose of varying the torque produced by the motor. The principal object of the invention is to provide a brush holder mounted for angular movement on the casing of the motor andcapable of' adjustment for increasing or decreasing the torque by varying the points of commutation with respect to the magnetic eld, Another ob ject is to provide a brush holder comprising a supporting bracket having mounted thereon a plurality'of brush holding devices which are interchangeable with each other. Still another object is to provide means whereby motors may be employed with an unusual range of voltage and of cycle variation. Anothervfeature 1s the provision of means for permittin the removal of the brushes without distur ing the setting of the holder with respect to the armature of the motor. The apparatus also comprises means for preventing the accidental removal of the brushes from the holders when the armature and cpmmutator are removed from the motor casing. A further important object of the invention is to provide improved means for forming anelectrical contact between the electrical supply conductors and the brush proper without the-necessity of using auxiliary shunt wires. The improved brush holder comprises improved means for making a positive connection between thexsupply conductors and the brushes-and the simplified construction permits the use of stampmgs formed of material having high electrica-l conductivity, such as bronze, brass, copper and the-like.

The nature of the invention will be more fully understood from the following specification taken with the accompanying drawings, in which'lF 1 is a section on the line 1-1 of Fig. 2,100 ing in the direction of the arrows, showing the relation' of the brush holder to the armature of the motor; Fig. 2 is a fragmentary section taken on the line 2 2 ofFig. 1 showing a top plan view of gne of the brush aholders and a sectional v1ew through the casing of the other brush holder; Fig. 3 is an enlarged section on the line 3-3 the plane of the armature shaft, a portion of f the holder being broken away; Fig. 6 is a perspective view of the brush holder bracket;

and Fig. 7 is a partial inside elevation of the'.

end wall of the dynamo casing with the brush holder, brushes and armature removed.

The invention may be employed in connection with electric dynamos of various types, but is illustrated in the drawings in connection with an electric motor comprising a casing 10 having an end wall 11 provided with a bearing 12 for the armature shaft 13` on which -is mountedthe armature and the commutator 15. The end wall 11 of the motor casing is provided with an annular flange 16 on which is mounted the brush holder supporting bracket 17, having the form shown particularly in Fig. 6. This bracket comprises a plate having formed vtherein a curved notch or aperture 18 adapted to coact with the outer surface of the flange 16 so that the bracket may be adjusted angularly to vary the positions of the points of commutation with respect to the magnetic field of the motor. The bracket 17 is secured in adjusted position by means 'of a clamping bolt or setl screw 19 engaging an aperture 20 in the bracket and an elongated slot 21 formed in the end wall 11 of the motor casing. The bracket 17 is further provided with two outwardly extending flanges 23 each of which carries a brush holderdesignated by the numeral 24. Each brush holder is made -up of ltwo ' complementary plates 25 and 26 which are provided with laterally extending ears 25* and 26 respectively, having holes therein to be engaged by the bolts 27 which extend throu h apertures 28 in the anges 23, the bolts. eing insulated from the flanges of the longitudinal guideway 32 of rectangular cross-section which vis formedvas a groove or recess in the plate 25, and which is adapted to receive and be closely titte-d by a brush 33, formed of carbon or the like, which projects downwardly -through the lower end of the brush holder` and contacts with the peripheral surface of the commutator 15. The flanges 23 on the bracket are preferably so arranged that the longitudinal axes of the brushes 33 are inclined to the radii of the armature in the direction in which the commutator rotates, this being anti-clockwise, as viewed in Fig. 1. Each brush 33 is provided at its outer end with a cylindrical projection 34 having the same diameter as the thickness of the brush, as shown in Figs. 3 and 4, and each of these lugs 34 has secured thereto the inner end of a coil spring 35. These springs project slightly beyond the edges of the brushes and are adapted to slide in grooves 36 and37 which are formed in the plates 25 and 26, re-

spectively, by pressing or stamping outwardly the metal of these plates. The grooves 36 and 37 terminate above the inner ends of the brush holders, thereby forming shoulders 38 which are adapted to engage the inner ends of thev springs 35, when the arma-ture is removed from the motor or when the brushes become greatly worn, so that the accidental dropping outof the brushes is prevented and the extent of inward movement is limited.y

f The outer end of each spring is secured pressed positions, wherein they maintain the A brushes 33 in contact with the armature 15, by means of yokes 42, each comprising a curved plate 43 adapted to pass over the outer end of each brush holder, and two lateral arms 44 which extend downwardly on opposite sides of the brush holder, as shown particularly in Fig. 3. These arms are provided at their inner ends with lugs 45 having a pivotal engagement with notches 46 formed in the plates 25 and 26 so that the yokes can be moved toward and from their normal positions. 42 is limited by the flanges 47 Awhich project inwardly from the outer ends of the plates 43 so that when the yokes are in their normal positions, as shown in Fig. 3, theflanges 47 engage the sides of the guideways 32 and When in this position, each yoke is held against removal by the engagement of the rounded head 40a of the adjacent spring cap with an aperture 48 formed in the plate 43.

When the yokes are moved toward the left, as viewed in Fig. 5 after releasing the parts 402l from the recesses 48, the springs 35 ex# pand and the brushes may then be wlthdrawn The extent of movement of the yokes outwardly through the guideways 32, using the springs as handles.

An electrical connection is made to each brushholder through angesl 5() which are formed on the plates 25 and which are adapt'- ed to be connected to the supply conductors 51 through which the electric current passes to the brushes. A ange 50 is formed on each side of each of the brush holders so that they may be interchanged with each other, the connection being made to the innermost flange of each holder. It will be apparent that the design of the bracket 17 is such that the two brush holders are mounted substantially ninety degrees apart and the flanges 50 extend downwardly so that the electrical connections to the conductors 51 are made from below, as illustrated in Fig. 1. A positive electrical connection is ma'dc'from the casing of each holder 24 to its brush through the yoke 42, cap 40 and spring 35 so that it 1s unnecessary to depend on the contact of the brushl with the walls of the guideway 32 and the use of auxiliary shunt wires is not required. The end casing 11 of the motor is preferably provided with an aperture l1a through which access may be had to the brush holders and the supporting bracket, this opening being normally closed by a suitable cover. I

Electric motors equipped with this invention may be'adapted to various uses but they may be employed with'particular advantage in connection with adding machines where it is desirable, by a simple adjustment, to adapt an electric motor, such as a series wound motor of the universal type, to the driving of adding machines of ditferent capacity. This may be accomplished by adjusting the bracket 17 in order to vary the angular position of the brushes on the commutator and thereby alter the current passing through the armature in different parts of the magnetic field for the purpose of varying the torque produced on the motor shaft. If it be desired to increase the torque of the motor, the brush holding bracket may be adjusted in a clockwise direction, as viewedin Fig. 1, and if it be desired to decrease the torque of the motor the brushes may be readily adjusted in a counterclockwise direction. When the v invention is applied to a generator, the effect ofthe angular adjustment will be to vary the terminal voltage together with the armature reactions and to produce other electrical and magnetic effects as will be apparent to those skilled in the art.

Although one form of the invention has been shown and described by way of illustration, it will be understood that it may be constructed in various other embodiments withoutdeparting from the scope of the appended claims.

We claim:

1. In combination, a dynamo having a casing provided with a flange, a plate extending throughout a portion of the periphery of said flange, said plate lying in a plane normal to the axis of the dynamo. means for adjusting said plate on said flange about said axis, arms formed integrally with and extending transversely to said plate, and brush holders mounted on and insulated from said arms.

2. In combination, a dynamo easing having an annular flange, a plate having oppositely directed hook members adapted partially to surround said flange, means for securing saidv plate in adjusted position, a pair of arms extending transversely from opposite sides, of said plate, brush holders carried by and insulated from said arms, and brushes slidably mounted in said brush holders.I

3. In combination a brush holder having a guideway therethrough, a brush mounted in said guideway, a spring mounted in said v guideway and connected to said brush, and shoulders formed on said brush holder for engaging the end of said spring to limit the movement thereof.

THEODORE S. BINDSCHEDLER. PETER J. KOSTER.

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