US3784856A

US3784856A - Brush holder assembly

Info

Publication number: US3784856A
Application number: US00276675A
Authority: US
Inventors: C Preston
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1972-07-31
Filing date: 1972-07-31
Publication date: 1974-01-08
Anticipated expiration: 1991-01-08
Also published as: BR7305686D0

Abstract

The invention is a motor brush holder assembly including a tubular holder member and a brush member freely slidable in the holder with spring means between the two biasing them apart. One of the members, generally the brush, has longitudinal surface groove means part of its length and terminating short of the brush end to form a stop. The other holder member has a fixed projecting means for slidable reception in the groove and the holder is deformable so the brush can be inserted past the stop so the brush is freely slidable in the holder and the stop prevents separation from the holder unless it is deformed. Thus, the entire assembly is preassembled for later use in the motor frame and only the actual functional parts alone form the preassembly.

Description

United States Patent 1191 Preston 1 BRUSH HOLDER ASSEMBLY [75] Inventor: Charles F. Preston, Brockport, NY.

[73] Assignee: General Electric Company,

- Bridgeport, Conn.

22 Filed: July 31,1972

211 Appl. No.; 276,675

FOREIGNPATENTS OR APPLICATIONS 790,189 9/1935 France....- 310/247 1111 3,784,856 145 Jan. 8, 1974 Primary Examiner-R. Skudy v AttorneyLawrence R. Kempton et al.

[5 7] ABSTRACT The invention is a motor brush holder assembly including a tubular holder member and a brush member freely slidable in the holder with spring means be tween the two biasing them apart. One of the members, generally the brush, has longitudinal surface groove means part of its length and terminating short of the brush end to form a stop. The other holder member has a fixed projecting means for slidable reception in the groove and the holder is deformable so the brush can be inserted past the stop so the brush is freely slidable in the holder and the stop prevents separation from the holder unless it is deformed. Thus, the entire assembly is preassembled for later use in the motor frame and only the actual functional parts alone form the preassembly.

10 Claims, 4 Drawing Figures 1 BRUSH HOLDER ASSEMBLY BACKGROUND OF ri-nz INVENTION 1. Field of the Invention The invention pertains to a brush holder assembly as used in an electric motor frame wherein the assembly has means by which the brush may be held in the brush holder for easy preassembly and placement in position in the frame and the brush is then freely movable for smooth sliding in the holder for biased contact against the commutator.

2. Description of the Prior Art Many types of brush holder assemblies have been devised for different specific applications and these have generally been directed to easily removable assemblies and are directed to improvements of individual parts or reducing the cost and number'of parts of the assembly in order to adapt it for machine:assembly as opposed to manual assembly and to improve the repairability of the device. In pigtail brushes, as opposed to those wherein the tubular holder generally forms the conducting path, snap clamps or clips have been provided to clamp on the brush to provide a surface against which a biasing force pushes the brush against the commutator, the clip reducing wear on the brush. On the non-pigtail type, the various improvements may prevent rotation, expelling, or twisting movement of the brush or other parts and are all aimed at simplifying the brush assembly structure. Various clamping means are generally used to hold the brush back in the brush holder so that it does not interfere or strike the commutator until it is in position.

One form of prior art that has successfully overcome the inherent tendency of the outwardly-biased brush from interfering with the commutator during assembly or replacement is shown in US. Pat. No. 3,656,018 of common assignment. The present invention is an alternate and generally improved version-of that structure.

SUMMARY OF THE INVENTION Briefly described, the invention is directed to a brush holder assembly that is used in an..electric motor frame which is designed for holding a rotating commutator. The device is improved for easy assembly or replace ment by providing a tubular flexible holder in the frame and supplying a generally matching brush disposed with one end in and slidable longitudinally in the holder. Spring means is disposed between the holder and brush to bias the brush outwardly in-the usual manner. For holding the brush in the holder'as a complete preassembly, longitudinal surface groove means generally in the form of a pair of opposite grooves is provided on one of the members such as the brush. The groove means terminates short of the end of the brush towards the holder in order to form a stop. There is provided fixed inwardly projecting means on the other member such as the tubular holder to register in the groove. The flexible holder is deformable so that the brush can be pushed in past the stop to thus engage the groove and projecting means whereby the brush is then free to slide in the holder and the stop prevents separation from the holder unless the holder is again deformed. The brush is then freely slidable in the normal fashion and is in operating position. Thus, the main object is to provide an improved-brush holder assembly that ensures that the brush and holder stay together as a compact assembly without other external means even though the brush is biased by an internal spring. The assembly is then placed in position in the motor and the brush is ready for normal operation.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT While the invention is applicable to any brush holder assembly, regardless of its shape, it will be convenient to describe it in the more common rectangular shape as shown and as used on many motors.

Referring to FIG. 1, there is shown an electric motor frame 10 that is designed to support a rotating armature 12 with the usual commutator 14. The frame may be of any material such as a die casting or molded plastic and is supplied with brush holder means such as upstanding holder lugs 16 having openings 18 therethrough for the reception of a brush holder assembly generally indicated at 20.

In the assembly of such electric motors, whether by automated machinery or manual labor, it is generally desired to preassemble the brush holder assembly 20 with its internal carbon brush and spiral spring as a package. This is then inserted into the means for holding the commutator brushes such ,as opening 18 so the brush contacts commutator l4 in'the normal manner. One of the troublesome assembly or repair problems is the tendency of the brush, because of its outward spring-bias, to interfere or get in the-way of the commutator or just plain drop out of the assembly. It is the purpose of this invention to provide a convenient and useful brush holder assembly wherein the parts stay together prior to insertion in the motor frame so that they may be easily handled without falling apart.

Referring next to FIG. 2, a typical improved brush holder assembly of the invention is shown. This generally comprises a tubular holder member 22 that is made to be flexible and is usually made of a flat piece of brass that is machine-folded to provide a tube open at one or both ends. Any form of tubular member of different materials and formed in any suitable manner or crosssection may be used. Generally, they are rectangular as shown and described. The tubular holder member 22 is provided with lug 24 for connection with the motor wiring. In order to retain the holder in the frame, any suitable retention means well-known in the art may be employed. Typically, as shown and described in US. Pat. No. 3,656,018 of common assignment, and as shown in FIG. 2, tubular holder 22 .may be folded from a flat piece of sheet material to provide a rectangular opening 26 centered on a longitudinally extending slot 28 extending along one side of the holder with the free ends or four corners, formed at the intersections of the slot and the rectangular opening, being bent to extend outwardly of the holder to form resilient or deformable projectionmeans such as tabs 30. When the holder is slidably positioned in opening 18 of the frame as seen in FIG. 1, forward and outwardly extending flexible tabs 30 are forced down and past an abutment 32 to drop into slot 34. The rear tabs lock on the other surface of abutment 32 and the holder is therefore lockingly engaged against longitudinal movement in opening 18 and secured to the holder. It may be released by insertion of a suitable tool to depress the forward tabs and then withdraw the holder. This is merely one way of retaining the assembly in a motor frame without the use of any additional parts although any suitable retention means will suffice.

In accordance with the invention, it is desired to provide means whereby the brush can be freely slidable at all times within the holder so the entire holder containing the spring-pressed brush can be handled as an integral preassembly without external clamps or the like and without fear of losing the brush or spring or having it interfere with any assembly or repair operation or, in other words, with just the use of the operating parts themselves to keep the brush in its holder and out of the way and avoid that problem where the brush pops out of the holder and gets lost. To this end, as best seen in FIG. 3, it is necessary to provide means to retain the generally matching brush member 36 within the holder since the brush is constantly urged out of the end of the holder under the effect of spring 38 disposed between the brush and holder members to bias them apart. In order to restrain the brush from sliding out of the holder, a suitable means is provided as part of the brush or holder whereby the brush can be inserted into the holder and held therein. This is accomplished by a typical tongue-and-groove arrangement common in many applications but not heretofore applied to a brush holder assembly in the form herein. As seen in FIG. 2, longitudinally extending surface groove means 40 is provided in at least one side of the brush and preferably on opposite sides as shown. The groove is designed to terminate short of the end of the brush closer to the holder or the end that is inserted in the holder, the termination forming a stop 42 which is nothing more than the ungrooved portion of the brush. In order to cooperate with this groove, the brush holder is provided with a fixed inwardly projecting means in the form of dimple 44 that is also generally applied on opposite surfaces as shown although one would suffice. The parts are put together by inserting the brush into the holder, which is deformable by virtue of the longitudinal slot 28 by being flexible, so that dimple 44 snaps into slot 40 in the brush and the holder then returns to its original shape with brush'36 freely slidable within the holder and the stop 42 engaging dimple 44 prevents expelling the brush as shown in FIG. 3. The only way the brush can be removed is again by deforming the holder to pull the members apart so that, in effect, the stop prevents separation from the holder unless the holder is again deformed. The brush and holder are thereupon locked in a freely slidable relation once the holder reverts to its unstressed shape.

Generally, the brush will be short enough that it does not fill in behind opening 26 so that the entire assembly can be pressed into the frame and the empty space behind opening 26 permits the inward flexing necessary to permit the holder in the area of tabs 30 to bend inwardly and past abutment 32 in the frame. In other words, a space is left behind the general area of opening 26 so that the parts will flexibly bend and snap in position in the frame. It will be apparent that the tongue-and-groove or dimple-and-slot, 44 and 40 respectively, could be reversed with the groove in the surface of the holder and the dimple. in the surface of the brush although this is inherently weaker since the dimple on the brush might easily shear off. Thus, the described construction is preferred although the operative locking parts could be reversed.

A modification of 'the same general arrangement is shown in FIG. 4 wherein the projecting means is an inwardly directed cantilevered lance 46 that is itself deformable as well as being that part of the flexible holder that is deformable. Again, the brush can be pushed past stop 42 and locked in the holder.

Preferably, the locking grooves are formed on at least two opposite sides of the members such as brush 36 for better operation and simple ease of manufacture. Similarly, in the dimple version of FIG. 2, the dimples are formed on at least two opposite surfaces of the holder to engage in each of the grooves. However, obvious modifications are a single locking combination such as shown by the single lance 46 in FIG. 4 used either singly or in pairs.

It will be seen that no additional structure is required other than the working parts when the projection and groove construction is used in conjunction with a deformable holder and the parts are merely snapped together where they are then held for inserting in the frame by projections separate from the dimples such as separate deformable means 30 to lockingly engage the holder in the frame. The combination permits easy assembly either manually. or automatically without the parts separating and permits assembly of the brush and holder elsewhere and separate from the frame. Also, by the construction shown and described, the brush is retained when the stop and fixed means abut so the brush can be replaced and will not expel into the commutator.

While there have been shown preferred forms of the invention, obvious equivalent variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practised otherwise than as specifically described, and the claimsare intended to cover such equivalent variations. a

I claim:

1. For use with an electric motor frame with means for commutator brushes, an improved brush holder assembly comprising,

a tubular brush holder member,

a brush member disposed with one end in and freely slidable longitudinally in said holder,

spring means between said members biasing them apart,

longitudinal surface groove means in one of said members,

said groove means terminating short of the end of said member closest said other member to form a stop, V

fixed projecting means on said other member for slidable reception in said groove means,

said holder being deformable for insertion of said brush past the stop to engage the groove and fixed means,

whereby said brush freely slides in said holder and said stop prevents separation therefrom without deforming said holder.

2. Apparatus as described in Claim 1 wherein said tubular holder has flexible means to at least partially deform the holder and permit insertion of said brush to lock it therein whereupon said holder reverts to its unstressed shape.

3. Apparatus as described in claim 1 wherein said holder is flexible and formed with a longitudinally extending slot along one side for deforming to permit engagement of said groove means and fixed means.

4. Apparatus as described in claim 1 wherein said fixed projecting means is disposed on at least two opposite sides of said other member, and

said one member has at least two matching grooves means.

-5. For use with an electric motor frame with means for commutator brushes, an improved brush holder assembly comprising,

a tubular flexible brush holder,

a generally matching brush disposed with one end in and slidable freely longitudinally in the holder, spring means between the holder and brush biasing the brush outwardly,

longitudinal surface groove means in said brush,

said groove means terminating short of said one end of the brush to form a stop,

fixed inwardly projecting means on said holder for slidable reception in said groove means,

said flexible holder being deformable to push said brush freely past the stop so as to engage the groove and projecting means, 1

whereby said brush slides in said holder and said stop prevents separation therefrom without deforming said holder.

6. Apparatus as described in claim 5 wherein said holder is formed with a longitudinally extending slot along one side for deforming .to permit engagement of said groove means and fixed means.

7. Apparatus as described in claim 1 wherein said projecting means is an inwardly directing dimple in said holder.

8. Apparatus as described in claim 1 wherein said projecting means is an inwardly directed cantilevered lance.

9. Apparatus as described in claim 1 wherein said projecting means is an inwardly directed dimple disposed on at least two opposite sides of the holder, and

the brush has at least two matching grooves means therefor. I g

10. Apparatus as described in claim 9 wherein said holder has additional deformable projection means extending outwardly therefrom and separate from said dimple to lockingly engage said frame and secure the holder therein.

Claims

1. For use with an electric motor frame with means for commutator brushes, an improved brush holder assembly comprising, a tubular brush holder member, a brush member disposed with one end in and freely slidable longitudinally in said holder, spring means between said members biasing them apart, longitudinal surface groove means in one of said members, said groove means terminating short of the end of said member closest said other member to form a stop, fixed projecting means on said other member for slidable reception in said groove means, said holder being deformable for insertion of said brush past the stop to engage the groove and fixed means, whereby said brush freely slides in said holder and said stop prevents separation therefrom without deforming said holder.

4. Apparatus as described in claim 1 wherein said fixed projecting means is disposed on at least two opposite sides of said other member, and said one member has at least two matching grooves means.

5. For use with an electric motor frame with means for commutator brushes, an improved brush holder assembly comprising, a tubular flexible brush holder, a generally matching brush disposed with one end in and slidable freely longitudinally in the holder, spring means between the holder and brush biasing the brush outwardly, longitudinal surface groove means in said brush, said groove means terminating short of said one end of the brush to form a stop, fixed inwardly projecting means on said holder for slidable reception in said groove means, said flexible holder being deformable to push said brush freely past the stop so as to engage the groove and projecting means, whereby said brush slides in said holder and said stop prevents separation therefrom without deforming said holder.

6. Apparatus as described in claim 5 wherein said holder is formed with a longitudinally extending slot along one side for deforming to permit engagement of said groove means and fixed means.

9. Apparatus as described in claim 1 wherein said projecting means is an inwardly directed dimple disposed on at least two opposite sides of the holder, and the brush has at least two matching grooves means therefor.