US3431446A

US3431446A - Electric motor brush holder,cap and spring

Info

Publication number: US3431446A
Application number: US655905A
Authority: US
Inventors: Allen J Petersen; Everett K Hansen
Original assignee: RAE MOTOR CORP
Current assignee: RAE MOTOR CORP
Priority date: 1967-07-25
Filing date: 1967-07-25
Publication date: 1969-03-04
Anticipated expiration: 1986-03-04

Description

M r h 1969 A. J. PETERSEN ETAL ELECTRIC MOTOR BRUSH HOLDER, CAP AND SPRING Filed y 25, 1967 hllm ALLEN J PETERSEN EVERETT K. HANSEN A 7'TORNEV a United States Patent 7 Claims ABSTRACT OF THE DISCLOSURE An electric motor brush holder with the motor housing having notches in the end for slidably receiving the brush holders. A cap fits on the brush holder to enclose the brush and its back-up spring. The spring has an enlarged portion in contact with a sleeve which slidably receives the brush, and the enlarged portion provides electrical contact between the brush and the sleeve.

Background of the invention This invention relates to an electric motor and its brush holder, and, more particularly, it relates to a means for securing the brush in position with respect to the com mutator without the requirement for any screw threads or other attaching means requiring a tool.

Brush holders are commonly attached to the motor housing by means of threads or other structure which retains the holder on the housing. Also, the brush itself is commonly retained in the holder by means of a threaded cap disposed behind the back-up spring of the brush.

The prior art also has brush holders and brushes which are secured without threaded means or the like. However, maintaining these prior art holders in the desired aligned position with respect to the commutator requires expensive and complicated mountings for the brush holder. Likewise, securing the brush back-up spring in the holder, even where threaded caps or the like are not employed. also requires expensive and complicated covers and like means. These prior art structures commonly require tools for assembly and disassembly of the brush holder both with respect to the motor housing as well as with regard to the removal of the brush from the holder. Examples of these prior art units are shown in patents of the United States under Nos. 2,045,293, 2,537,714, and 2,683,826.

Still further, the prior art brush holders do not provide a reliable means for conducting the electric current from the brush to the electric wire which makes connection with the brush. In this regard, the present invention provides an eflicient means for conducting electric current from the brush and through the brush sleeve and to the wire commonly connected to the brush sleeve. With the present invention, the commonly provided wire extending from the outer end of the brush and to the brush sleeve by means of a connecting disk or cap is not necessary. That is, the electric connection can be made through the back-up spring extending between the brush and being in electric contact with the brush sleeve.

It is also the object of this invention to provide a brush holder which is eflicient in conducting electric current, is accurately aligned with the commutator, which is sturdy and free of undo exposure to breakage, and is not susceptible to damage. Additionally, the holder has the aforementioned features, and it is easy and inexpensive to manufacture, repair, and it is compact with the motor main parts of the "housing and the armature.

Still another object and point of improvement in the present invention is the provision of a brush holder which provides for inspection, repair, replacement, and the like of the brush without requiring the use of tools in that 3,431,446 Patented Mar. 4, 1969 only a snap-cap is employed. Further, the cap provides for assurance of electrical contact between the brush the brush sleeve in that the cap engages the back-up spring for maintaining contact between the spring and the brush sleeve.

Brief description of the drawing FIG. 1 is a side elevational view of one embodiment of this invention, with parts thereof broken away.

FIG. 2 is an enlarged end view of a portion of FIG. 1 shown sectioned, and taken along the line 22 of FIG. 1.

FIG. 3 is a bottom plan view of FIG. 2.

FIG. 4 is a side elevational view of the brush holder of FIG. 2.

FIGS. 5 and 6 are bottom and side views, respectively, of the cap shown in FIG. 2.

FIGS. 7 and 8 are end elevational and side elevational views, respectively, of the back-up spring shown in FIG. 2.

FIGS. 9, 10 and 11 are sectional views similar to FIG. 2 but showing diiferent embodiments of the brush holder assembly.

Detailed description of the shown embodiments A motor housing 10 is shown to contain the usual stator 11, and armature 12 with commutator 13.

Armature shafts

14 and 16 extend beyond the generally cylindrically shaped housing 10, and beyond the end caps 17 and 18 which are shown to be bolted to the housing main body 10. Thus the armature 12 and its commutator 13 are mounted in the housing for the desired rotation, and brush holder assemblies 19 are mounted on the housing body 10 for the usual purpose of disposing the brushes 21 in sliding contact with the commutator 13. The housing 10 has notches 22 which slidably receive the brush assemblies 19, and, more particularly, the notches 22 snugly slidably receive the brush holders 23 which are made of a non-conductive material, such as plastic. The housing end cap 17, when fastened to the housing body 10 by the screws 24, or other conventional means, secure the brush holders 23 to the body 10 in the position shown in FIGS. 1, 2 and 3. Thus the assemblies 19 can be readily slid onto and off of the body 10 for the desired positioning and alignment of the brushes 21 with the commutator 13.

The brush holders 23 have openings 26 extending therethrough, and a brush sleeve 27 is disposed in the opening 26 in an axially fixed position. Thus the brush holder 23 has an end 28 extending externally of the housing 10 and terminating in an outer edge or surface designated 29. The opposite sides of the holder 23 have grooves 31 which slidably fit the thickness of the housing body 10 along the notch 22. Thus the holder 23 is held in a fixed position with respect to the body 10, except for sliding the holder 23 011 the body 10 when it is desired to remove the holder 23, and of course also when the assembly is made, the holder 23 can be slid onto the body 10.

FIG. 1 shows that electric wires 32 are in contact with the inner ends of the brush sleeves 27, and these wires 32 therefore make electric contact with the brush sleeves 27, in the usual manner. Also, in the usual manner, the brushes 21 are slidable in the brush sleeves 27 and make electric contact with the sleeves 27.

A cap or a closure 33 extends over the brush holder surface 29 and flush therewith, and the cap is also preferably made of a plastic material which is not electrically conductive. The cap 33 is also made of a flexible material so that it can be placed onto the holder 23, in the position shown, and it can be removed from the holder 23, both without requiring any special tools but necessitating only finger pressure. Thus the cap 33 has projections or tangs 34 which extend inwardly on the cay 33 on opposite sides thereof, and the tangs 34 snap into the notches or openings 36 on opposite sides of the brush holder 23. Thus the main portion 37 of the cap 33 extends over the brush holder surface 29 to close the upper end of the opening 26.

FIGS. 2, 7 and 8 show a brush spring 38 which is in electric contact with the brush at the spring end 39 and which is in electric contact with the upper surface 41 of the brush sleeve 27. That is, the spring 38 has an enlarged portion or coil 42 which is generally of the size of the cross section of the brush sleeve 27 so that the coil 42 rests upon the surface 41, as shown in FIG. 2. Also, the spring 38 has the upper end 43 in contact with the cap 33 to urge the spring coil 42 downwardly into electric contact with the brush sleeve surface 41. Therefore, electric contact is assured between the brush 21 and the brush sleeve 27.

Finally, it should be noted that the cap 33 has a centrally disposed projection 44 which extends downwardly toward the spring 38 and therefore it guides the spring 38 both by keeping the spring from slipping out of a central position and by urging the spring into contact with the sleeve 27, as indicated in FIG. 3.

FIG. 9 shows a different configuration of the spring, and here a spring 46 has an enlarged coil 47, like the coil 42, in contact with the upper end of the brush sleeve 27 The spring 46 also has a disk 48 attached to coils 49 on the spring 46, and the disk 48 is urged downwardly by the projection 44 and, with the spring coils 49, the enlarged coil 47 is urged against the brush sleeve 27. In this instance, a flexible wire 51 extends between the brush 21 and the disk 48 to make electric contact therebetween for conducting current therebetween. However, current is conducted along the spring 46 and to the sleeve 27 by means of the enlarged coil 47, as in the embodiment shown in FIG. 2, in addition to the function of the flexible wire 51.

FIG. shows a spring 52 extending to a disk 53, and another spring 54 is shown above the disk 53 and is in contact with the cap 33. Thus the spring 54 is urged downwardly onto the disk 53 which in turn is urged into contact with the upper surface of the sleeve 27 to make electric contact therewith.

FIG. 11 shows a spring 56 disposed between the brush 21 and cap 33. The spring has an enlarged coil 57 at its upper end, and the coil 57 is of a size to be in contact with the upper surface 41 of the sleeve 27 when the coil 57 is pressed downwardly by the cap 33. That is, the space between the brush sleeve surface 41 and the cap 33 is such that the coil 57 snugly occupies the space so that it is in contact with the surface 41, as desired. Here it will also be noted that the cap projection 44, being disposed centrally on the cap 33, assures that the spring coil 57 will be held in contact with the sleeve 27. This feature is also shown in FIG. 3 where it will be observed that the sleeve 27 is slightly off center on the brush holder 23 so that the centrally located projection 44- will maintain the spring aligned with the sleeve 27 and also in contact with the upper surface 41. It will be noted that in these several embodiments the length of the sleeve 27, or at 60 least its spacing of its upper surface 41 from the cap portion 37 may vary.

What is claimed is:

1. In an electric motor, a housing, a stator and an armature disposed in said housing and including a commutator, a cover removably connected to an end of said housing for rotatably supporting said armature and enclosing said stator and said armature in said housing, a brush holder on said housing and extending externally of said housing in an end having a terminal edge, a brush sleeve disposed in said holder and being countersunk therein to terminate short of said terminal edge of said brush holder extending from said housing, a brush removably disposed in said brush holder and being in abutment with said commutator, a closure removably attached to the externally extending portion of said brush holder for securing said brush in said brush holder, a coil spring disposed between said closure and said brush for yieldingly urging said brush into abutment with said commutator, the improvement comprising said closure being a flexible cap to be snapped onto and off from said edge of said brush holder and, extending over said spring and urging said spring into the direction of said brush, and said spring having an enlarged piece thereon disposed over the end of said brush sleeve and in contact therewith and arranged to be urged into contact with said sleeve by said cap.

2. The subject matter of claim 1, wherein said cap is a plastic cap including tabs for removably attaching to said brush holder by finger pressure only, and said brush holder being grooved and said housing being notched for removably receiving said brush holder adjacent said cover, all being arranged to eliminate screw threads for holding said brush holder and said cap.

3. The subject matter of claim 1, wherein said enlarged piece on said spring is an enlarged coil of said spring and making electrical contact with said brush sleeve.

4. The subject matter of claim 3, wherein said enlarged coil is intermediate along the length of said spring, and one end of said spring is connected to said brush and the other end of said spring is in abutment with said cap.

5. The subject matter of claim 3, wherein said enlarged coil is on one end of said spring, and said brush sleeve is spaced from said cap a distance equal to the thickness of said enlarged coil for urging the latter against the end of said brush sleeve.

6. The subject matter of claim 1, including a length of spring extending between said cap and said enlarged piece for urging the latter into contact with said brush sleeve.

7. The subject matter of claim 1, wherein said cap includes a projection for guiding said spring axially of said brush holder.

References Cited UNITED STATES PATENTS 1,933,628 11/1933 Kitto 3l0--247 3,152,274 10/1964 Fox 31{)247 3,187,214 6/1965 Brezosky 310-239 FOREIGN PATENTS 795,998 6/1958 Great Britain. 960,557 3/1957 Germany.

WARREN E. RAY, Primary Examiner.

R. SKUDY, Assistant Examiner,