US2276066A - Brush-holder assembly - Google Patents

Description

BRUSHHOLDER AS'SEMBLY Filed Feb. 16, 1940 2 Sheets-Sheet l III/I MIIIIIIIIIIII WITNESSES: INVENTOR 6? FaymohaA/fchucK.

ATTORN EY March 10, 1942. R w SCHUCK 2,276,066

BRUSHHOLDER' ASSEMBLY Filed Feb. 16, i940 2 Sheets-Sheet 2 WITNESSES: INVENTOR ATTORNEY Patented Mar. 10, 1942 UNITED STATES PATENT OFFICE BRUSH-HOLDER ASSEMBLY Pennsylvania Application February 18, 16441, Serial No. 319,293

Claims.

The present invention relates to current-collecting devices for dynamo-electric machines, and more particularly to a brushholder assembly which is of simple and inexpensive construction.

Brushholders for dynamo-electric machines are usually pivotally mounted and spring means of various types are used to hold the brush against the slip ring or commutator with which it cooperates, so that the brush pressure is kept more or less constant as the brush wears down. This type of construction is subject to the difficulty that the brushholder often tends to stick as a result of dirt or corrosion in the pivotal mounting. Such sticking is obviously very objectionable since it makes it impossible to maintain the desired brush pressure throughout the life of the brush, and it also makes it very difiicult to change or adjust the brushes. Brushholder assemblies of this type are also usually relatively complicated and are difficult to assemble on the machine with which they are to be used and to adjust to give the desired brush pressure.

The object of the present invention is to provide a brushholder assembly of simple and ineX pensive construction which is very easy to assemble in a machine.

A further object of the invention is to provide a brushholder assembly which cannot stick because of dirt or corrosion on any part of the assembly.

A' still further object of the invention is to provide a brushholcler assembly in which the brush pressure is adjustable and in which such adjustment can easily be made.

Other objects and advantages of the invention will be apparent from the following detailed description, taken in connection with the accompanying drawings, in which:

Figure 1 is an elevational view of a brushholder assembly, with parts in section;

Fig. 2 is a sectional View approximately on the line IIII of Fig. 1;

Fig. 3 is a perspective view of a brushholder, and

Fig. 4 is a perspective view of a supporting f block.

The invention is shown in the drawings as applied to a vertical alternating current machine having a shaft l and an upper end bracketZ. A cover plate 3 is secured in any suitable manner to the inside of the bracket 2, and the shaft passes through this plate and may be journaled in a bearing mounted in the plate. The cover plate 3 has radially outwardly extending portions l at each side on which the parts of the brushholder assembly are supported. Slip rings ii are mounted on the shaft and are connected to the rotor windings of the machine in any usual or desired manner. It is to be understood that although a slip ring motor has been shown Lil) in the drawings for the purpose of illustration, the brushholder assembly of the present invention may be used equally well in cooperation with a commutator on either a direct current or alternating current machine.

The brushholder 6 of the present invention is shown in detail in Fig. 3 and consists of a generally channel-shaped member of sheet steel, or other suitable material. The web portion of the channel is extended at one end of the brushholder and bent up to form a pivot l, while at the other end the web portion is cut out to provide an opening in which a carbon brush 8 may be secured by screws 9, or in any other desired manner. At the opposite end of the brushholder from the pivot 'l, the side Walls are brought together and clamped by means of rivets ID. A lead ll may be clamped under one of the rivets iii, as shown in Fig. 2. In the illustrated embodiment, three brushholders 6 are used, one for each of the slip rings 6, and the leads II from the three brushholders may be connected to terminals l2 mounted on a terminal board it secured in any convenient position in the bracket 2.

The brushholders 6 are supported in position by a support block it. The block I l may be molded of any suitable insulating material and, as shown in Fig. 4, it is formed with three slots i5 for the reception of the three brushholders 6. The width of these slots is such that the brushhoiders fit snugly in them. At one side of the block a ll-groove Iii is formed running at right angles to the slots 15. An extension i1 is formed at one end of the block !4, and the block is mounted in position in the motor by securing this extension to the end surface of one of the extending portions 4 of the cover plate 3 by means of screws l8, so that the block extends vertically dcwnward, as clearly shown in Fig. 1. The brushholders 5 are inserted-in the slots is with their pivots l engaged in the V- groove It so that they are free to move about the pivots l to bring the brushes 8 into engagement with the corresponding slip rings 5. It is to be noted that the brushholders are not secured to the supporting block Hi in any way, but are merely placed in the slots, which restrain movement of the brushholders axially of the shaft, while permitting them to move freely about their pivots 1.

Spring provided to maintain the brushes 6 in engagement with the slip rings 5 under the desired pressure. th'i purpose a second support block Iii is prcvided on the opposite side of the shaft from the brushholders, and this block is secured to the extending portion 4 of the cover plate 3 on that side of the motor by means of screws 2d. The block I9 is preferably also molded of a suitable insulating material and has three shallow grooves in each of which a spring support 2! is placed. Each of the spring supports 2! may consist of a piece of sheet metal having two angularly related portions. One portion 22 fits into the slot of the block W and is secured therein by means of screws 23, or in any other suitable manner, while the other portion 24 of the spring support extends outward from the slot beyond the shaft. This portion 24 of the spring support has three holes 25 in its end which serve as points of attachment for a helical tension spring 25. The other end of the spring 26 is secured in a hole 2? in the end of the brushholder 6, so that the spring tends to rotate the brushholder about its pivot l and thus holds the brush in engagement with the slip ring under a predetermined pressure Three holes 25 are provided in the spring support 2i and these holes are located at diiferent distances from the brushholder 6, so that by moving the spring 25 from one of these holes to another a change in the tension of the spring and therefore in the brush pressure may be obtained.

It should now be apparent that a brushholder assembly has been provided which is very simple and inexpensive, and which is very easy to assemble in position in the motor. In assembly, it is only necessary to placethe brushholders in the slots of the block Ml and to attach the springs 26 between the brushholders and the proper holes 25 in the spring supports 2! to give the desired brush pressure. It should also be particularly noted that since the brushholder 6 is not secured to the block l4 in any way, and since the pivot l merely engages in a V-groove in the block and is not fastened to it, it is impossible for the brushholder to stick no matter how much dirt or corrosion may be present, but it will always move freely about its pivot, and thus the desired brush pressure will always be maintained. The provision of the three holes 25 makes possible a very easy adjustment of the brush pressure since it is only necessary to unhook the spring 28 from one hole and hook it into another to change the pressure. It will be understood, of course, that any suitable number of holes 25 may be provided to give the desired number of adjustments.

Although a specific embodiment of the invention has been illustrated and described, it is to be understood that its usefulness is not limited to the particular embodiment shown, but that it may be used with any type of motor having a rotary current carrying element for cooperation with brushes, and that it may be used with any type of motor construction. The invention is not limited, therefore, to the exact details of construction shown in the drawings and described above, but in its broadest aspects it includes all equivalent embodiments and modifications which come within the scope of the appended claims.

I claim as my invention:

1. In combination with a dynamo-electric chine having a shaft with a current-carrying element thereon, a brushholder having a pivot at one end thereof, a support member mount-ed at one side of the shaft, said brushholder being disposed in a slot in said support member with its pivot engaging in a V-groove in the support member, but not being secured thereto and being free to move about the pivot, a spring secured to the opposite end of the brushholder from the pivot, and a support plate mounted at the opposite side of the shaft from the brushholder, one

end of said spring being attached to the plate to draw the brushholder towards said current-carrying element.

2. In combination with a dynamo-electric machine having a shaft with a current-carrying element thereon, a brushholder having a pivot at one end thereof, a support member mounted at one side of the shaft, said brushholder being disposed in a slot in said support member with its pivot engaging in a V-groove in the support member, but not being secured thereto and being free to move about the pivot, a spring secured to the opposite end of the brushholder from the pivot, and a support plate mounted at the opposite side of the shaft from the brushholder, one end of said spring being attached to the plate to draw the brushholder towards said currentcarrying element, said plate having a plurality of points of attachment for the spring to provide different spring tensions.

3. A brushholder assembly for a dynamo-electric machine having a rotatable current-collecting device comprising a support block at one side of the current-collecting device. said support block having a slot therein extending transversely of the axis of the current-collecting device and a V-groove extending transversely of the slot, a brushholder disposed in said slot, said brushholder having a pivot at one end thereof which engages in the V-groove of the support block, and spring means attached to the brushholder at the opposite end from the pivot, said spring means tending to move the brushholder about its pivot towards the current-collecting device.

t. A brushholder assembly for a dynamo-electric machine having a rotatable current-collecting device comprising a support block one side of the current-collecting device, said support block having a slot therein extending transversely of the axis of the current-collecting de vice and a V-groove extending transversely of the slot, a brushholder disposed in said slot, said brushholder having a pivot at one end thereof which engages in the V groove of the support block, a spring support at the opposite side of the current-collecting device from said support block, and a tension spring attached to said spring support and also attached to the brushholder at the opposite end thereof from its pivot, said spring tending to move the brushholder about its pivot toward the current-collecting device.

5. A brushholder assembly for a dynamo-electric machine having a rotatable current-collecting device comprising a support block at one side of the current-collecting device, said support block having a plurality of parallel slots therein extending transversely of the axis of the currentcollecting device and a V-groove extending transversely of the slots, a plurality of brushholders disposed in said slots, each of said brushholders having a pivot at one end thereof which engages in the V-groove of the support block. a plurality of spring supports at the opposite side of the current-collecting device from said support block. and tension springs attached to each brushholder at the opposite end thereof from its pivot and to a corresponding spring support. said springs tending to move the brushholders about their pivots toward the current collecting device.

RAYMOND W. SCHUCK.

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