GB2385212A

GB2385212A - Assembling brush gear in a small-sized motor

Info

Publication number: GB2385212A
Application number: GB0221192A
Authority: GB
Inventors: Kazuyuki Yamamoto
Original assignee: Mabuchi Motor Co Ltd
Current assignee: Mabuchi Motor Co Ltd
Priority date: 2001-09-12
Filing date: 2002-09-12
Publication date: 2003-08-13
Also published as: JP3914109B2; CN1180525C; CN1405953A; JP2003164116A; GB0221192D0

Abstract

A motor has a brush holder assembly 9 which includes two brush opening pins 11 corresponding to two brush arms 12. The motor has an end bell 5 inside which a projecting part 7 is formed. When, during manufacture, the brush holder assembly 9 is fitted to the end bell 5 of the motor, the projecting part 7 comes into contact with the brush opening pins 11 and causes them, in turn, to move into contact with, and then open, the bush arms 12. The projecting part 7 is shaped so as to release the opening pins 11 when the brush holder assembly reaches is final position. Consequently, it becomes possible to set the brushes 13 onto the commutator 4 after assembly of the case, rotor and end bell. As the brushes 13 wear in use, the brush arms 12 approach each other and the brush opening pins 11 can be structured to come into contact with the brush arms 12 when the brushes reach their end of life, preventing contact between the brush arms 12 and the commutator 4.

Description

238521 2

BRUSH DEVICE OF SMALL-SIZED MOTOR AND

MANUFACTURING METHOD THEREOF

The present invention relates to a brush device of a small-sized motor wherein a brush slide part can easily and surely be set on a commutator, and a manufacturing method thereof The assembling of a conventional smallsized motor has been performed using a case which is made of a metal material in the form of a hollow cylinder with a bottom to which a magnet as a stator magnetic pole is attached, a rotor comprising a rotor magnetic pole and a commutator integrally assembled on a shaft, and 16 an end bell to which two brush arms respectively supporting brushes are attached, A f t e r inserting the rotor which is assembled integrally on the shaft from an opening part of this case, the end bell is fitted to close the opening part of the case. To the brush arms, an elastic force is given in a direction! bringing the brushes into contact with each other. Therefore, when fitting the 20 end bell, it is necessary to bring two brush slide parts into contact with the commutator in the state where they are open relative to each other.

As a method of setting the brush slide parts of a small-sized motor on the commutator in the state where they are open, a method is performed wherein, from the end bell opening part, brush opening pins are inserted using a special jig, 25 the commutator of the rotor is set at a specified position in the state where the brushes are open, and the brush opening pins are removed after closing the brushes.

However, in the case of such a brush setting method, it is necessary to provide an opening part for inserting a special jig such as a brush opening pin for setting the brush slide parts on the commutator. Especially, in the case where - a waterproof function is needed,such as a case where the small-sized motor is used 5 for a power window of a vehicle, it is necessary to seal the opening part specially.

Furthermore, it is difficult to set a brush holder by which brushes or a brush fixing part is held, after assembling the case, rotor, and end bell.

FIG. 8 is a drawing showing a brush setting method by another prior art (Japanese Utility Model Laid-Open No. 4-61467). At the time of

l 0 assembling a brush body to a brush housing, a guide flange is formed on the brush body along the end surface of the brush guide. The guide flange is provided to the brush holding plate to which the brush is attached. The drawing is shown in the state where the brush exists at three positions on the way while assembling the brush. In the drawing, the brush positioned at a first position 15 shows the state where the brush inserted into the brush housing from the lower side is just brought into contact with the brush guide. In the drawing, in a second brush position, it is shown that a force to open the brushes horizontally is produced by the guide flange sliding along the end surface of the brush guide following the rising of the brush body. Then, in the drawing, at the third brush 20 position, the state where the brushes are open to the utmost is shown, and after this, by a little more rising, the guide flange is separated from the engagement with the brush guide, and as a result, the brush comes into contact with the commutator However, in the case of such a brush setting method, the brush guide 25 actually and directly acts on the brush holding plate to which the brushes are attached to open them, and therefore, there are some cases where a damage is caused to the (carbon) brush itself. Furthermore, there is a problem that it is

not easy to find the occurrence of damages after the assembling has been performed. Furthermore, as mentioned above, the configuration is made such that the brush guide and the guide flange act on each other directly, and therefore, when a breakdown is caused, it is impossible to be disassembled for the repairing and the reuse.

5 According to a first aspect of the present invention a brush device for a small-sized motor, comprising: a hollow generally cylindrical metal case having an end to which a stator magnetic pole is attached; an end bell which is fitted to close an opening of the metal case; 10 a rotor comprising an integrally assembled rotor magnetic pole and a commutator on a shaft rotatably supported by bearings respectively provided to the end part of the metal case and the end bell; and a brush holder supporting two brush arms to which two brushes are attached respectively, the brushes being arranged to come into contact with 15 the commutator, wherein the brush holder supports two brush opening pins provided corresponding to the two brush arms, the brush opening pins being positioned respectively facing each of the brush arms and being arranged to come into contact with the brush arms to open the brush arms and the brushes 20 supported thereby relative to each other when a force acts in a direction on the corresponding brush arm side, the end bell including an opening part having a side wall extending generally perpendicularly to the rotor shaft direction, the brush holder being fitted and attached to the end bell opening part, the end bell side wall 25 including a projecting part which is arranged to engage with the brush opening

pins to act in the direction of opening the brush opening pins relative to each other at the time of fitting of the brush holder, and to release the engagement of the brush opening pins at the final fitting position.

According to a second aspect of the present invention the brush device 5 of a small-sized motor according to claim 1, wherein the projecting part has a specified height sufficient for the tip parts of the brush opening pins to be engaged, and a width that increases in width so that the side of the projecting part comes into contact with the brush opening pins to open the brush opening pins relative to each other during insertion of the brush holder until 10 the contact with the brush opening pins is released at the final insertion position of the brush holder.

The present invention avoids the need to provide an opening for inserting a brush opening pin by a special jig in an end bell, and by this, to make it easier to provide a waterproof function to a motor end bell part without 15 any special parts.

Furthermore, the present invention makes it unnecessary to provide the special jig for setting a brush slide part to a commutator, and makes it possible to set a brush holder to which brushes or a brush fixing part is held and to set the brush slide part to the commutator after the assembling of the 20 case, a rotor (commutator) and end bell.

The present invention permits easy assembly without causing damage to the (carbon) brush itself, and in the meantime, to make reuse possible by performing the disassembling and the repairing when a breakdown is caused.

The present invention provides a brush opening pin on the brush 25 holder, and a brush opening pin opening and closing mechanism in the end bell. The brush slide part is set to the commutator at the same time when the brush holder to which the brush fixing part is held is set to the end bell.

Consequently, the special jig for setting the brush slide part to the commutator

and the opening part for inserting the brush opening pin for the end bell are made unnecessary.

The projecting part is preferably formed such that it has a specified height sufficient for the tip parts of the brush opening pins to be engaged, and 5 a width that becomes actually and gradually wider so that the side of the projecting part comes into contact with the brush opening pins to open them relative to each other according to the insertion of the brush holder until the contact with the brush opening pins is released at the final inserting position of the brush holder.

10 Preferably, brush opening pin has a specified length extending approximately in parallel with the brush arm, and that the tip part of the brush opening pin is shaped like an L bent on the end bell opening part side wall where the projecting part is provided, so that at least the tip part thereof comes into contact with the side of the projecting part.

15 The brush opening pin may be fixed by integral molding to a base integrally formed to the brush holder so as to come into contact at right angles to the extending direction of the brush arm.

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a view showing an outside appearance of a small-sized motor to which the present invention is applied, and it showers the state where an assembling is completed. In FIG. 1A, a front view is shown, which is seen in the state where a rotor shaft is set in a horizontal direction, and in FIG. 1B, a side view seen from an 5 end bell side is shown; FIG. 2 is a cross sectional view of a completed small-sized motor shown in FIG. 1;

FIG. 3 is a view of the same small-sized motor as exemplified in FIG. 1 and FIG. 2, but it shows the state where a brush holder is not inserted yet into an end 10 bell opening part though an end bell is fitted to the metal case; FIG. 4 is a view of the same small-sized motor as exemplified in FIG. 3, but it shows the state of the stage on the way when the brush holder is inserted into the end bell opening part; FIG. 5 is a rough perspective view for making it easy to understand a 15 mutual relation of a main configuration; FIG. 6 is a perspective view showing a second example of a brush opening pin, and it shows the brush holder before the attachment of the brush arms; FIG. 7 is a perspective view showing the second example of the brush opening pin, and it shows the brush holder in the state where the brush arms are 20 attached; and FIG. 8 is a view showing a brush setting method according to the related art.

FIG. 1 is a view showing an outside appearance of a small-sized motor to 25 which the present invention is applied, and it shows the, motor in an assembled state.

FIG. 2 is a cross sectional view of a completed small-sized motor shown in FIG. 1. In any drawing, in A on the left side in the drawing, a front view

seen in the state where the rotor shaft is positioned in the horizontal direction is shown, and in B on the right side in the drawing, a side view seen from the end bell side is shown The small-sized motor 1 of the present invention can have the same configuration as the conventional configuration except for the end bell part 5 and the attaching structure of the brushes. A metal case 15 is made of a metal material and shaped like a hollow cylinder with a bottom, and in the meantime, a magnet 17 as a stator magnetic pole is attached. Furthermore, on an outer periphery of the metal case 15, a yoke 2 is attached. A rotor 3 is composed by integrally assembling the rotor magnetic pole and a commutator 4 on a shaft 16.

10 This rotor 3 is supported rotatably by bearings respectively provided to the metal case bottom part and an end bell 5. The electric current supplied from the external power source through the brushes and the commutator flows to the winding wound around the rotor magnetic pole, and consequently, the motor can rotate. The above described configuration and action are common, and any more 15 detailed description will be omitted.

The small-sized motor to which the present invention is applied is characterized by the configuration of the brush holder to which the brushes are attached and furthermore, of the end bell to which the brush holder is attached.

After inserting the rotor 3 integrally assembled on the shaft 16 from the opening of 20 the hollow cylindrical metal case 15 with a bottom, the resin end bell 5 is fitted to close the opening of the metal case 15. In this state, the rotor 3 is supported rotatably, but the brushes are not brought into contact with the commutator 4, yet.

As shown in the drawing, to the end bell 5, an opening part is provided, which is made of an integrally molded resin side wall extending in the direction at 25 right angles to the rotor shaft direction (lower side in the drawing). To this end bell opening part, a brush holder is fitted and attached, which supports brush arms to which brushes are attached. At this moment at least part of the end bell

opening part must be at the position facing to the commutator 4 so that the brushes come into contact with the commutator. In the process of fitting the brush holder in the opening part from the lower side in the drawing, by the configuration which is the characteristic of the present invention, two brush arms 5 to which brushes are respectively attached are opened, and after that, finally, two brushes come into contact with the commutator. As for this, furthermore, by referring to FIG. 3 to FIG. 5, a first example of the brush opening pin will be described below.

FIG. 3 is a view of the same small-sized motor as exemplified in FIG. 1 and 10 FIG. 2, and it shows the state where a brush holder 9 is not inserted into an end bell opening part 6 yet though the end bell 5 has already been fitted to the metal case 16. FIG. 5 is a rough perspective view for making it easy to understand the mutual relation of a main configuration. The shape of the cross section of the end bell opening part 6 (shape seen from the brush holder inserting side) can be any 15 shape such as a circle, but the exemplified configuration is made on a cross section shaped approximately like a rectangle. Therefore, the end bell opening part 6 has four wall surface parts, and these four wall surface parts are composed of two wall surface parts facing to each other in the shaft axial direction and two wall surface parts facing to each other in the direction at right angles thereto. On the inside of 20 either of two wall surface parts facing to each other in the shaft axial direction among these four wall surface parts (on the inside on the nearer side of the magnetic pole in the shaft axial direction, in the example shown in the drawing), a projecting part 7 is provided, which is engaged with the brush opening pins 11 to open them, which will be described later in detail.

25 Furthermore, it is possible that at the time of inserting the brush holder 9 into the end bell opening part 6, on the inside of another wall surface part different from that where the projecting part is provided, one or more linear projections or

grooves which function as the guide rail for suitably positioning the brush holder are properly provided and in the meantime, linear grooves or projections corresponding thereto are provided to the brush holder 9, which is not the characteristic of the present invention. Furthermore, it is also possible to provide 5 linear projections which perform the function of increasing the strength of the wall surface part of the synthetic resin end bell opening part.

It is unnecessary for the projecting part 7 engaged with the brush opening pin 11 to be high, but it is made to have a specified height sufficient for the tip part of the brush opening pin 11 to be engaged, and the width of the projecting part 7 is 10 made large so that the side of the projecting part 7 surely comes into contact with the brush opening pins 11 to gradually open them relative to each other according to the insertion of the brush holder 9. However, at the final insertion position of the brush holder 9, the projecting part 7 corresponding to the brush opening pins 11 does not exist, and consequently, the contact with the brush opening pins 11 is 16 released. Thus, in the projecting part 7, as long as the sides on both sides thereof are structured to be suitably engaged with the brush opening pins 11, it is not always necessary to be flat in the center of the projecting part 7, and no problem is caused even if it is made a little higher or lower than the height of the side parts.

The brush holder 9 has a brush fixing part 10 to which two brush arms 12 20 respectively supporting brushes 13 are fixed. On the inside of each of these two brush arms 12 facing to each other, the brush opening pin 11 is positioned, and is fixed to the brush fixing part 10. The brush opening pin 11 has a specified length in the extending direction of the brush arm approximately in parallel with the brush arm, and in the meantime, it has an elastic force to some extent. For 25 example, it may be made of a synthetic resin with a specified thickness and a specified width. It is necessary for at least the tip part of the brush opening pin 11 to come into contact with the side of the projecting part 7 provided at the end 9

bell opening part. Therefore, it is preferable that the tip part of the brush opening pin 11 is shaped like an L bent on the end bell opening part side wall side where the projecting part 7 is provided, and in the meantime, that the bent inside has a tapered shape (in the drawing of the brush holder 9 in FlG. 3A, only the tip part 5 bent like an L of the brush opening pin 11 is seen). Since this portion has a tapered shape, it is possible to pull out the brush holder 9 after the completion of the motor, and the disassembling when a breakdown is caused becomes possible.

Furthermore, when the brush opening pin tip parts come into contact with the side of the projecting part to be open relative to each other, they come into contact with 10 the brush arms respectively and act to open the brush arms. In order to come into contact with the brush arm 12, as shown in the drawing of the brush holder 9 in FIG. 3B, the tip part of the brush opening pin 11 is structured to be wide.

The total of the brush holder 9 including the brush opening pins 11 and the brush fixing part 10 can be integrally molded by a synthetic resin. The brush arm 15 12 passes through the brush fixing part 10, and is electrically and mechanically connected to the terminal (not shown in the drawing) for the external connection, or it is also possible to be integrally formed with that. Since the configuration is made like this, when the brush holder 9 is inserted and attached to the end bell opening part 6, the opening for the inserting of the brush opening pins does not 20 exists, which is necessary for setting the brushes on the commutator in the prior art, but in order to make the waterproof function surer, in the clearance between the brush holder 9 and the end bell opening part 6, a sealing member such as a packing can be put according to the technique which is well known itself.

FIG. 4 is a view of the same small-sized motor as exemplified in FIG. 3, but 25 it shows the state of the stage on the way when the brush holder 9 is inserted into the end bell opening part. The state where the brush opening pins 11 come into contact with the wide portion of the projecting part 7 and therefore, the brush arms -1

12 and the brushes 13 supported thereby are largely opened is shown in the drawing. After this, when the brush holder 9 is furthermore inserted into the end bell opening part, the engagement between the projecting part 7 and the brush opening pins 11 is released, and the final assembled state is made, which has been 5 described above by referring to FIG. 2.

The brush opening pin 11 can be structured to come into contact with the brush arms 12 just at the last period of the carbon brush wearing. By taking this configuration, the slide between the brush arms and the commutator does not occur after the wearing of the carbon brush. Accordingly, as long as the wearing of the 10 commutator is not largely increased, the use as a motor becomes possible by exchanging the carbon brush (the carbon brush is softer than the commutator and the wearing is faster, and therefore, the above described exchanging becomes possible, and consequently' the reuse of the motor becomes possible).

Furthermore, as the material itself of the brush 13 and the brush arm 12 15 supporting that, the same material as is conventionally and usually used can be used. FIG. 6 and FIG. 7 are perspective views showing a second example of the brush opening pin, and FIG. 6 shows the brush holder before the brush arms are attached, and FIG. 7 shows the brush holder in the state where the brush arms are 20 attached. The configuration exemplified here is the same as that of the first example described by referring to FIG. 1 to FIG. 5 except for the brush opening pin and the related configuration thereof However, FIG. 6 and FIG. 7 are shown in the vertically reversed state when compared with FIG. 5.

The brush holder 9 has, similarly to the first example, the brush fixing part 25 10 to which two brush arms 12 respectively supporting brushes 13 are fixed. Then, in the case of this second example, totally, the base 14 on the plate is integrally molded by a resin to extend from the brush fixing part 10 in the extending -11

direction of the brush arm 12. It is arranged that a printed board can be attached on one surface side of this base 14. On the other surface side of this base 14 (side where the brush arms are positioned), a pair of brush opening pins 11 are fixed by integral molding to the base 14 to respectively come into contact with the brush 5 arms 12 at right angles to the extending direction of the brush arms 12.

The brush opening pin 11 composed like this can be engaged with the projecting part (omitted in the drawings of FIG. 6 and FIG. 7) provided to the end bell opening part side wall when the brush holder 9 is inserted into the end bell opening part, similarly to the above described first example. Furthermore, 10 similarly to the first example, it is preferable that the inside of the tip part of the brush opening pin 11 (side in the brush arm base part direction) has a tapered shape so that the brush holder 9 can be pulled out after the completion of the motor. When compared with the first example, the brush opening pin of this second 15 example can be structured to have a shorter length, and therefore, it becomes possible to easily ensure the rigidity sufficient for overcoming the elasticity of the brush arm. Furthermore, the brush opening pin of this second example is attached in the direction at right angles to the brush arm extending direction, and therefore, it becomes possible to surely and uniformly act on the brush arm.

20 Furthermore, by this, it is also possible to suppress the vibration of the brush arm during the rotation of the motor to lower the noise. Furthermore, when the brush opening pin is integrally resin-molded together with the base and the brush fixing part, the brush opening pin is connected to the base, and therefore, the die shape becomes simple.

25 According to the present invention, it can be made unnecessary to provide an opening for inserting the brush opening pin by a special jig to the end bell, and -12

furthermore, the special jig for setting the brush slide part to the commutator can be made unnecessary Furthermore, in the case of the present invention, it is possible to set the brush holder by which the brushes or the brush fixing part is held, and to set the 5 brush slide part to the commutator after the assembling of the case, rotor (commutator), and end bell, and consequently, not only the brush slide part of a small-sized motor can easily and surely be set to the commutator but also the reduction of man-hour and the improvement of function are achieved.

Furthermore, in the case of the present invention, easy assembling is 10 achieved without causing any damages to the (carbon) brush itself, and in the meantime, when a breakdown is caused, the reuse is possible by performing the disassembling and repairing.

-13

Claims

1. A brush device for a small-sized motor, comprising: a hollow, generally cylindrical metal case having an end to which a 5 stator magnetic pole is attached; an end bell which is fitted to close an opening of the metal case; a rotor comprising an integrally assembled rotor magnetic pole and a commutator on a shaft rotatably supported by bearings respectively provided to the end part of the metal case and the end bell; and 10 a brush holder supporting two brush arms to which two brushes are attached respectively, the brushes being arranged to come into contact with the commutator, wherein the brush holder supports two brush opening pins provided corresponding to the two brush arms, the brush opening pins being positioned 15 respectively facing each of the brush arms and being arranged to come into contact with the brush arms to open the brush arms and the brushes supported thereby relative to each other when a force acts in a direction on the corresponding brush arm side, the end bell including an opening part having a side wall extending 20 generally perpendicularly to the rotor shaft direction, the brush holder being fitted and attached to the end bell opening part, the end bell side wall including a projecting part which is arranged to engage with the brush opening pins to act in the direction of opening the brush opening pins relative to each other at the time of fitting of the brush holder, and to release the engagement 25 of the brush opening pins at the final fitting position.

2. The brush device of a small-sized motor according to claim 1, wherein the projecting part has a specified height sufficient for the tip parts of the brush opening pins to be engaged, and a width that increases in width so that the side of the projecting part comes into contact with the brush opening pins 5 to open the brush opening pins relative to each other during insertion of the brush holder until the contact with the brush opening pins is released at the final insertion position of the brush holder.

3. A brush device of a small-sized motor according to claim 1 or claim 2, 10 wherein the brush opening pin has a specified length extending approximately in parallel with the brush arm, and the tip part of the brush opening pin is shaped like an L bent on the end bell opening part side wall where the projecting part is provided, so that at least the tip part thereof comes not contact with side of the projecting part.

4. The brush device of a small-sized motor according to any one of the preceding claims, wherein the brush opening pin is fixed by integral molding to a base integrally formed to the brush holder so as to come into contact generally perpendicularly to the extending direction of the brush arm.

5. A manufacturing method of a brush device of a small-sized motor, the motor having a hollow cylindrical metal case with an end to which a stator magnetic pole is attached, an end bell which is fitted to close an opening of the metal case, a rotor which comprises an integrally assembled rotor 25 magnetic pole and a commutator on a shaft rotatably supported by bearings respectively provided in an end part of the metal case and the end bell, and a brush holder supporting two brush arms to which two brushes are attached

respectively, the brushes arranged to come into contact with the commutator, the method comprising steps of: providing two brush opening pins corresponding to two brush arms on the brush holder, 5 positioning the brush opening pins respectively on the insides facing each of the brush arms and arranged to come into contact with the brush arms to open the brush arms and the brushes supported thereby relative to each other when a force acts in the direction on the corresponding brush arm side, 10 providing an opening part on the end bell including a side wall extending in the direction generally perpendicular to the rotor shaft direction, providing a projecting part on the end bell side which is arranged to engage with the brush opening pins to act in the direction of opening the brush opening pins relative to each other and to release the engagement at 15 the final fitting position, and after inserting the rotor into the metal case, fitting the end bell to close the opening of the metal case, and after that, fitting and attaching the brush holder to the end bell opening part.

20

6. The manufacturing method according to claim 5, wherein the projecting part has a specified height sufficient for engaging the tip parts of the brush opening pins and a width that gradually increases so that the side of the projecting part comes into contact with the brush opening pins to open the brush opening pins relative to each other during insertion of the brush holder 25 until the contact with the brush opening pins is released at the final insertion position of the brush holder.

7. The manufacturing method according to claim 5 or claim 6 wherein the brush opening pin has a specified length extending approximately in parallel with the brush arm, and the tip part of the brush opening pins is shaped like 5 an L bent on the end bell opening part side wall side where the projecting part is provided, so that at least the tip part thereof comes into contact with the side of the projecting part.

8. The manufacturing method according to any one of claims 5 to 7, 10 wherein the brush opening pin is fixed by integral molding to a base integrally formed to said brush holder to come into contact at right angles to the: extending direction of the brush arm.

9. A brush device for a small-sized motor substantially as shown in or as 15 described with respect to any one of the Figures 1 to 7 of the accompanying drawings.

10. A method of manufacturing a small-sized motor substantially as described with respect to any one of Figures 1 to 7 of the accompanying 20 drawings.

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