JP2593300B2 - Motor brush holding device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a brush holding device for an electric motor.

(Prior Art) Conventionally, small motors used for electric motors, especially for starters such as motorcycles, have been reduced in weight as brush holding devices.
For the purpose of improving reliability, there has been a tendency to use a brush holder integrally formed of resin.

For example, JP-A-59-148548 discloses that a holder main body constituting a brush holder and a brush box accommodating a brush are separately formed of resin, the holder main body is mounted in a bracket, and a brush is provided on the holder main body. It discloses that by integrally forming a holding portion for storing a box and by fitting and fixing a brush box to the holding portion, the dimensional accuracy of a portion holding the brush is improved, and the durability of the brush is improved. I have.

(Problems to be Solved by the Invention) As described above, when the brush holder is formed of resin, the cost of the mold is relatively high when producing various kinds of small quantities. Also, if the temperature of the brush is high, brush wear will be accelerated,
There is a demand for a proposal for a means for efficiently dissipating the heat generated by the brush.

In view of such problems and demands, the object of the present invention is to eliminate the resin-molded brush holder, reduce the mold cost burden in the production of many kinds and in small quantities, and further reduce the thermal resistance that causes the brush temperature to rise. It is to provide a brush holding device which can be lowered.

(Means for Solving the Problems) In order to achieve the above object, the present invention relates to a brush holding device for an electric motor, in which a metal front bracket, a cylindrical yoke, and a metal rear bracket are connected by assembly bolts. The rear bracket is provided with two brush box holding portions facing inward in the radial direction, and the brush box holding portion has a pair of side walls formed on the inner wall of the annular frame portion of the rear bracket. Protruding from the back wall,
With a U-shaped cross section with one end open in the axial direction,
A bridging portion connected to the rear wall is projected from the annular frame portion, and a female screw for screwing the assembling bolt is formed in the bridging portion. The rear end of the shaft is supported, and the brush box is fitted into the brush box holder from the axially open end. It is configured to be drawn through.

(Operation) In the present invention, the metal rear bracket is provided with two brush box holding portions facing inward in the radial direction,
The brush box holding portion has a pair of side walls and a rear wall projecting from the inner wall of the annular frame portion of the rear bracket, and has a U-shaped cross section with one end opened in the axial direction. It can be fitted into the brush box holder from the end. The rear bracket is a part of the casing and also has a function of supporting the armature. In the present invention, the rear bracket also has a function of holding the brush box. That is,
In the present invention, the function performed by two separate members, the bracket and the holder body, is performed by one member of the rear bracket in the present invention. Therefore, while two sets of dies are required in the prior art, only one set of dies is required in the present invention, and the die cost burden in the production of many kinds of small quantities is reduced.

Further, in the present invention, the material of the brush box is the same as that of the prior art (phenol resin), but since the brush box is directly fitted into the brush box holding portion formed integrally with the metal rear bracket, The heat of the brush is quickly radiated to the outside through the rear bracket. On the other hand, in the related art, as described in (Prior Art), the brush box (brush box) and the holder main body are made of resin, and the resin holder main body is mounted on a metal bracket. . Generally, the thermal conductivity of metal is 100-1000 of resin
Since the present invention does not include the resin holder body of the related art, thermal resistance which causes an increase in brush temperature can be further reduced.

(Example) Hereinafter, an example of the present invention will be described.

1 to 3 show a first embodiment of the present invention. FIG. 1 shows an electric motor of a starter for a motorcycle. A casing 1 has a front bracket 2, a cylindrical yoke 3, and a rear bracket 4 made of aluminum die-cast.
A rear cover 5 is attached to a rear portion of the rear bracket 4. The front bracket 2 and the rear bracket 4 on both sides of the yoke 3 are connected by an assembling bolt 6 penetrating through the yoke 3 and are integrally assembled in a separable manner. The rear cover 5 is attached to the rear bracket 4 by joining the outward flange portions of the two and connecting them with screws 7.

An amateur 9 having a commutator 8 is provided in the casing 1.
And a magnet 10, and the front end and the rear end of the rotating shaft 11 of the armature 9 are supported by a bearing 12 provided on the front bracket 2 and a bearing 13 provided on the rear bracket 4.

In FIGS. 1 to 3, two brush box holding portions 14 diametrically opposed to each other in the diameter direction of an annular frame portion 4A are integrally formed on a rear bracket 4 made of aluminum die cast. Each brush box holding portion 14 is provided to extend inward in the radial direction from the inner wall of the annular frame portion 4A, and has a front side (left side in FIG. 1) which is perpendicular to the axis of the motor. wall
4E is integrally formed. A cross section perpendicular to the axis of the brush box holding portion 14 is opened toward the radially inner side X,
The cross section along the annular frame portion 4A has a U-shape opened toward the rear cover 5 direction Y. In other words, the brush box holding portion 14 is formed by projecting a pair of side walls 4D and a back wall 4E on the inner wall of the annular frame portion 4A of the rear bracket 4 so as to have a U-shaped cross section open at one end in the axial direction. Have been.

A brush box 15 made of an insulator such as phenolic resin is fitted into the brush box holder 14 having a U-shaped cross section from the open end on the rear side in the axial direction (the right side in FIG. 1). The side is similarly pressed by a pressing plate 16 formed of an insulator such as a phenol resin.

The holding plate 16 is an annular plate fitted into the annular frame portion 4A of the rear bracket 4, and a rear portion 4B of the rear bracket 4 is passed through an opening provided at the center thereof. Here, the holding plate
16 is made by punching a phenolic resin plate. The outer peripheral shape of the rear portion 4B of the rear bracket 4 is not a cylinder, and the surfaces (upper and lower surfaces in FIG. 2) of the two brush box holding portions 14 are notched flat at substantially the same position as the bearing 13. . This increases the space between the ring frame 4A and the brush box 15A.
Is made to be able to be fitted from the rear side.

After the holding plate 16 is fitted in the annular frame portion 4A of the rear bracket 4, the rear cover 5 is fixed. This rear cover 5
An annular holding part fitted into the annular frame part 4A of the rear bracket 4
5A is provided, and the brush box 15 is accurately and immovably held in the axial direction of the rotating shaft 11 by the pressing portion 5A.

The pigtail 18 connected to the brush 17 fitted into the brush box 15 is drawn out from the opening of the brush box 15 through the cutout 15A cut radially outward and the open side of the brush box holding portion 14. . The brush 17 is urged inward by a spring 19 and is in contact with the commutator 8 at a predetermined pressure.

The rear part 4B of the rear bracket 4 is connected to the annular frame part 4A at a position different from the brush box holding part 14 by a bridging part 4C extending radially outward (in the horizontal direction in FIG. 2). The bridging portion 4C is formed so as not to contact the holding plate 16 in order to make the holding plate 16 effective for holding. In addition, a bridging portion 4C, which is connected to the rear wall 4E, protrudes from the annular frame portion 4A, and a female screw to be screwed with the assembling bolt 6 becomes
4C is formed.

Next, the operation of the first embodiment of the present invention will be described.

When the brush 17 is replaced, when the screw 7 is loosened and the rear cover 5 is removed, the presser plate 16 comes off, so that the brush box 15 can be easily taken out from the brush box holding portion 14. Then, the brush 17 stored in the brush box 15 is taken out and replaced. At this time, disassemble the casing 1 of the electric motor,
Front bracket 2, yoke 3, rear bracket 4,
Since there is no need to divide it into amateurs 9 etc., the exchange work is extremely simple.

Also, as described above, a recess is formed in the metal rear bracket 4 to form a brush box holding portion 14, and a brush box 15 made of an insulator is fitted into the holding portion 14 and fixed by means such as a holding plate 16 or the like. This eliminates the need for the conventional brush holder.

In addition, if the insulating brush box 14 is made of ceramic having a good thermal conductivity, the thermal resistance between the brush box 14 and the metal bracket is reduced, and the effect of suppressing the acceleration of brush wear due to a rise in brush temperature is also obtained. Can be In addition, omitting the holding plate 16,
The brush box 15 can be fixed with an adhesive.

FIGS. 4 and 5 show a modification of the first embodiment in which an insulating washer 20 is interposed between the end face of the commutator 8 and the rear portion 4B of the rear bracket 4. The diameter of the insulating washer 20 is slightly longer than the flat portion of the rear portion 4B of the metal rear bracket 4.

Therefore, when the end of the life of the brush 17 is worn, the spring 19 is extended, and the brush 17 moves toward the commutator 8. However, pigtail 18 is an insulating washer
When the pigtail 20 comes into contact with the outer periphery, its movement is restricted, so that the pigtail 18 does not contact the metal rear bracket 4 and short-circuit.

FIGS. 6 to 8 show a second embodiment in which a rear bracket 21 made of aluminum die-cast also has a function of a rear cover.
An example will be described.

The annular frame portion 21A of the rear bracket 21 is provided integrally with a recess formed by projecting a pair of side walls 21C from the inner wall thereof and including two brush box holding portions 22 extending inward in the radial direction. The open end of the brush box holding portion 22 having a U-shaped cross section faces the front side Z (to the left in FIG. 6). Brush box holder 22
A rear wall is integrally formed at the rear (right side in FIG. 6) end, and the rear wall is perpendicular to the axis of the electric motor and is a part of the rear bracket 21. As shown in FIG. 8, a brush box 24 made of sheet metal is fitted into the brush box holding portion 22 having a U-shaped cross section from the front side (the left side in FIG. 8) via an insulating sheet 23.

At that time, the lip box holder 22, the insulating sheet 23, the brush box
The three of 24 are adhered by an adhesive. The pigtail 18 from the brush 17 is pulled out from the front side Z of the rear bracket 21. In this embodiment, since no rear cover is provided, the rear portion 21B of the rear bracket 21 has a cylindrical shape. In addition,
The same elements as those in the first embodiment are denoted by the same reference numerals.

In the embodiment shown in FIG. 6 to FIG.
Although it is necessary to disassemble the motor casing 1 when replacing the motor, there is an advantage that not only the conventional brush holder is unnecessary but also the number of parts is reduced as in the case of the first embodiment.

Furthermore, since the metal brush box 24 is brought into contact with the metal bracket via the insulating sheet 23, the thermal resistance between the two is significantly reduced. Generally, the thermal conductivity of metal is 100 to 1000 times better than that of resin.

As the insulating sheet 23, for example, a polyimide film “Kapton” (manufactured by Toray Industries, Inc.), a Nomex sheet (manufactured by DuPont), a heat radiation insulating sheet (DENKA, manufactured by Shin-Etsu Silicone Co., Ltd.), etc. As such, high thermal conductive adhesive "ramdite" (manufactured by Denka) or the like is used.

In the embodiment shown in FIGS. 6 to 8, the brush box 24 is fixed with an adhesive, but it is also possible to use a holding plate as in the first embodiment or fix it by screwing. . Further, the rear bracket 21 does not necessarily need to be formed by aluminum die casting.

(Effects of the Invention) In the prior art, the brush box is fitted and fixed in the holder of the holder body constituting the brush holder, and the brush holder has only the function of holding the brush box. On the other hand, according to the present invention, as described in claim 1, a rear bracket that forms a part of the casing and supports the rear end of the rotating shaft of the amateur is provided with a brush box holding mechanism. Functions are also used. As described above, in the present invention, the rear bracket, which is a part of the casing and also supports the armature of the amateur, also has the function of holding the brush box. Brush holder is no longer needed. In addition, by moving the brush box in the axial direction of the brush box holding portion, the mounting and dismounting of the brush is reliably performed.

In addition, the rigidity of the rear bracket is improved by projecting the brush box holding portion and the bridging portion in the annular frame portion without reducing the rigidity because there is no opening for mounting the brush box holding portion. No distortion or the like occurs during the die-casting production, and the accuracy of the shaft center can be improved.

Further, the thermal resistance between the brush and the metal rear bracket / front bracket is significantly reduced, and the brush temperature is not increased, so that the brush wear is reduced, and as a result,
The life of the motor is prolonged.

[Brief description of the drawings]

1 to 3 show a first embodiment of the brush holding device of the present invention. FIG. 1 is a sectional view, FIG. 2 is a right side view of FIG. 1 with a rear cover removed, and FIG. FIG. 4 is a partial view of a rear bracket showing a brush box holding portion, and FIGS.
FIG. 4 is a sectional view, and FIG.
6 to 8 show a second embodiment of the brush holding device according to the present invention. FIG. 6 is a sectional view, and FIG. 7 is a rear bracket viewed from the direction of FIG. FIG. 8 is a front view as seen from the VII-VII direction, and FIG. 8 is a view showing the relationship between the brush box holding portion, the insulating sheet and the brush box. DESCRIPTION OF SYMBOLS 1 ... Electric motor casing 2 ... Front bracket 3 ... Yoke 4 ... Rear bracket 4A ... Annular frame part 4D ... Side wall 4E ... Back wall 6 ... Assembling bolt 14 ... Brush box holding part 15 ... Brush box 16 Hold down plate 17 Brush 18 Pigtail 21 Rear bracket 21A Ring frame 21C Side wall 22 Brush box holder 24 Brush box

Claims (1)

(57) [Claims] An electric motor casing is formed by connecting a metal front bracket, a cylindrical yoke, and a metal rear bracket with an assembling bolt, and the rear bracket is opposed to the rear bracket radially inward. The brush box holding portion is provided with a pair of side walls and a rear wall protruding from the inner wall of the annular frame portion of the rear bracket to have a U-shaped cross section with one end opened in the axial direction. A projecting bridge portion connected to the rear wall is formed in the annular frame portion, and a female screw for screwing the mounting bolt is formed in the bridge portion;
The rear end of the armature is supported by a bearing provided at the rear of the rear bracket, and the brush box is fitted into the brush box holder from the axially open end. A brush holding device for an electric motor, which is drawn through a notch of a brush box and an open side of a brush holding portion.