US3480814A - Brush holder assembly with insert - Google Patents

Description

Nov. 25, 1969 c. J. AMREIN 3,430,314

BRUSH HOLDER ASSEMBLY WITH INSERT Filed June 5, 1968 INVENTOR CARL J. AMREIN BY WQ M ATTORNEY United States Patent BRUSH HOLDER ASSEMBLY WITH INSERT Carl J. Amrein, Baltimore, Md., assignor to The Black and Decker Manufacturing Company, Towson, Md.,

a corporation of Maryland Filed June 3, 1968, Ser. No. 733,863 1 I Int. Cl. H02k /14 US. Cl. 310247 6 Claims ABSTRACT OF THE DISCLOSURE Summary of the invention The present invention deals with an improved brush holder assembly which includes a strengthening, stabilizing and heat dissipating metallic insert retained within a hollow insulating body. The insert slidably guides a brush as well as a terminal which electrically connects a lead and the brush and the insertis constructed to facilitate'maximum brush life while protecting the brush assembly and preventing unintended withdrawal of the terminal and lead therefrom after full brush wear.

Main objects of the present invention, therefore, are to provide an improved brush holder assembly for use in an" electric motor, which assembly provides strength, stability and protection for the overall assembly and which prevents the electric lead and terminal from unintentionally withdrawing from the assembly where they can contact exteriorly accessible metal parts.

Further objects of the present invention are to provide an improved brush holder assembly of the above character which maximizes brush life and facilitates good heat dissipation.

Additional objects are to provide an improved brush holder assembly of the above character which is relatively inexpensive to manufacture and assemble, rugged in construction and reliable in use.

Other objects and advantages of the present invention will become more apparent from a consideration of the detailed description to follow taken in conjunction with the drawings annexed hereto.

Brief description of the drawings FIG. 1 is a view, partly in elevation and partly in section, illustrating a brush holder assembly embodying the present invention;

FIG. 2 is an exploded perspective view illustrating the insulating outer body and metallic insert of the present invention;

FIG. 3 is a sectional view of FIG. 1 taken along the line 33 thereof;

FIG. 4 is a sectional view of FIG. 3 taken along the line 44 thereof; and

FIG. 5 is a sectional view of FIG. 3 taken along the line 5-5 thereof.

Broad statement of the invention Broadly described, the present invention relates to a brush holder assembly which comprises a hollow insulating body, a hollow metallic insert retained within 3,480,814 Patented Nov. 25, 1969 ice said body, said body and said insert having at least one open end, a carbon brush slidably disposed in said insert and adapted to extend outwardly of said one end, spring means behind and adapted to bias said brush outwardly of said one end, said body and said insert having aligned slots along one side thereof, an electric lead extending through said slots and having a terminal slidably guided within said insert and held in electrical contact with said brush by said spring means, said lead adapted to move along said slots as said brush wears, and means on said insert remote from said slot therein adapted to cooperate with said terminal and prevent withdrawal of said terminal from said one open end of said insert when said brush wears.

In another aspect, the present invention includes a brush holder assembly comprising a hollow, elongated metallic member having a carbon brush slidably disposed therein, a compression spring within said member and adapted to bias said brush outwardly of one end of said member, said member having a first elongated slot extending inwardly from said one end, and second and third elongated slots intermediate the ends of said member and on opposite sides of said first slot, electric lead means extending through said first slot and including a terminal slidably guided within said member and held in electrical contact with said brush by said spring, said terminal having a pair of projections extending into said second and third slots, whereby to prevent withdrawal of said terminal from said one end of said metallic member.

Detailed description Referring now more specifically to the drawings, a brush holder assembly embodying the present invention is illustrated generally at 11 in FIGS. 1 and 3-5 and is seen to include an elongated generally rectangular body 13 adapted to be fixed in suitable fashion upon a motor housing (not shown). The body 13 preferably is constructed from a moldable, insulating material, for example, a phenolic, and has a generally rectangular cavity 15 adapted to receive a generally complementary shaped metallic insert 17. The insert 17 also is hollow and may be pressed into the cavity 15 or the insert 17 may be provided with outwardly bent tabs 19, 21 which permit easy assembly of the insert to the body 13 but substantially prevent its withdrawal. A carbon brush 23 is slidably guided in the insert 17 and is normally biased outwardly of one end thereof by a compression coil spring 25 positioned within the insert 17 and behind the brush 23. If desired, the insert 17 and the cavity 15 can be arcuately shaped, as shown in FIGS. 2 and 3, to accommodate the spring 25, and the insert 17 can have inwardly bent tabs 27, 29 at its inner end against which the spring 25 seats.

The spring 25 normally holds the brush 23 against a commutator 31 forming part of a rotatable armature 33 of an electric motor. Electric current is [delivered to the brush 23 through an electric lead 35 and a terminal 37 connected to the end of the lead 35 and held in electrical contact with the brush 23 by the spring 25. As shown, the lead 35 extends through aligned slots 39, 41 extending to one end of the body 13 and insert 17, respectively, and the terminal 37 preferably is between the spring 25 and brush 23. Thus, as the brush 23 wears, the lead 35 moves through the slots 39, 41, while the terminal 37 moves along and is guided within the insert 17 for movement toward the commutator 31.

In order to prevent possible injury to the operator, it is important that the terminal 37 be prevented from pulling out of the brush assembly 11 even after full brush wear. To this end, the terminal 37 is provided with at least one and preferably a pair of projections 43, 45, one

to either side of the leads 35, which are received in a pair of elongated slots 47, 49 formed intermediate the ends of the insert 17, one on either side of the slot 41. The body 13 is provided with relief areas 51, 53 adjacent the slots 47, 49 to accommodate the projections 43, 45, respectively. The ends of the slots 47, 49 near the commutator 31 form abutments 55, 57 which limit the advancing movement of the terminal 37 toward the commutator and prevent its withdrawal from the insert 17 even if the brush 23 comes out of the insert 17. By providing a plurality of abutments, the terminal 37 is now more positively prevent-ed from unintentionally pulling out of the assembly 11 than it would be were just one abutment provided.

It will be appreciated that the metallic insert 17 serves to rigidify and stabilize the body 13 which is constructed from a less rigid material and which has the open slot 39 for the lead 35. Furthermore, the insert 17, being metallic in composition, serves as a heat sink to help dissipate heat from the brush 23 during motor operation and therefore increases brush life.

By the foregoing, there has been disclosed an improved brush holder assembly calculated to fulfill the inventive objects hereinabove set forth, and While a preferred embodiment of the present invention has been illustrated and described in detail, various additions, substitutions, modifications and omissions may be made thereto without departing from the spirit of the invention as encompassed by the appended claims.

I claim:

1. A brush holder assembly which comprises a hollow insulating body, a hollow metallic insert retained within said body, said body and said insert having at least one open end, a carbon brush slidably disposed in said insert and adapted to extend outwardly of said one end, spring meansbehind and adapted to bias said brush outwardly of said one end, said body and said insert having aligned slots along one side thereof, an electric lead extending through said slots and having a terminal slidably guided within said insert and held in electrical contact with said brush by said spring means, said lead adapted to move along said slots as said brush wears, and means on said insert remote from said slot therein adapted to cooperate with said terminal and prevent withdrawal of said terminal 4 from said one open end of said insert when said brush wears.

2. An assembly as defined in claim 1 wherein said terminal and said insert are provided with cooperable abutment means preventing withdrawal of said terminal.

3. An assembly as defined in claim 1 wherein said insert has at least one elongated slot intermediate its length and which slidably receives a projection on said terminal.

4. An assembly as defined in claim 1 wherein said'i'nsert has a pair of elongated slots intermediate its length, one to either side of said first mentioned slot in said insert, said terminal having a pair of projections slidably received in said pair of slots.

5. An assembly as defined in claim 1 wherein said terminal is between said brush and said spring.

6. A brush holder assembly comprising a hollow, elongated metallic member having a carbon brush slidably disposed therein, a compression spring within said member and adapted to bias said brush outwardly of one end of said member, said member having a first elongated slot extending inwardly from said one end, and second and third elongated slots intermediate the ends of said member and on opposite sides of said first slot, electric lead means extending through said first slot and including a terminal slidably guided within said member and held in electrical contact with said brush by said spring, said terminal having a pair of projections extending into said secondand third slots, whereby to prevent withdrawal of said terminal from said one end of said metallic member.

References Cited UNITED STATES PATENTS 1,457,896 6/1923 Cook 310-247 2,477,352 7/1949 Stark 310-247 2,987,639 6/ 1961 Bayless et a1 310-247 3,339,098 8/1967 Burrows et a1 310-239 3,387,156 6/1968 Elow et a1. 310-249 3,431,446 3/1969 Petersen et a1. 310-247 3,436,576 4/1969 Klebe 310-239 MILTON O. HIRSHFIELD, Primary Examiner L. L. SMITH, Assistant Examiner

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