JP3575509B2 - DC motor brush holding device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a brush holding device for holding a brush that slides on a commutator of a DC motor.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a brush used for a starter motor is housed in a brush holder, and a front end surface thereof is always in contact with a commutator by a rear end surface being urged by a spring. In addition, a predetermined gap is secured between the brush holder and the brush so that when the brush is worn due to sliding contact with the commutator, the brush can move to the commutator side without trouble in the brush holder. .
[0003]
[Problems to be solved by the invention]
However, although the brush is urged to the commutator side by a spring, the movement of the brush generated due to engine vibration cannot be suppressed in the vicinity of the contact portion with the commutator, and the brush is held in the brush holder. There is a possibility that the side wall of the brush may be worn and the brush may be chipped or broken due to collision with the inner wall of the brush.
In addition, even when the commutator rotates, the brush moves near the contact portion with the commutator, which may cause the same problem as described above.
The present invention has been made based on the above circumstances, and an object of the present invention is to restrict the movement of a brush near a commutator contact portion, thereby avoiding problems such as brush side wall wear, brush chipping and cracking. And a brush holding device for a DC motor.
[0004]
[Means for Solving the Problems]
According to the first aspect of the invention, a thin sheet having flexibility is arranged between the commutator and the brush holder, and the brush is passed through the opening formed in the sheet. Here, the clearance between the inner peripheral edge of the opening and the outer peripheral surface of the brush is set smaller than the clearance between the inner peripheral surface of the brush holder and the outer peripheral surface of the brush (side surface of the brush). When the brush moves on the commutator from a predetermined contact position with respect to the brush, the sheet bends in the direction in which the brush moves before the side surface of the brush contacts the inner wall of the brush holder. To return the brush to a predetermined position. As a result, the movement of the brush in the vicinity of the commutator contact portion is restricted, so that it is possible to avoid abrasion of the side wall of the brush, chipping and cracking of the brush caused by the collision of the brush with the inner wall of the brush holder.
[0005]
Also, since the brush abrasion powder generated by the sliding contact with the commutator can be received by the sheet to some extent, the brush abrasion powder locally accumulates inside the DC motor, causing an electrical short circuit. Can be avoided. Furthermore, the fact that the sheet covers the contact portion between the brush and the commutator means that the sheet covers the location where the brush wear powder is generated, so that the effect of suppressing the diffusion of the brush wear powder is produced. As a result, the chance that the abrasion powder of the brush adheres to a portion of the DC motor that requires slippage, such as a bearing, is reduced, and the problem of poor slippage can be avoided.
[0006]
According to the invention of claim 2, a thin sheet having flexibility is arranged between the commutator and the brush holder, and the outer peripheral surface of the brush (brush) is formed on the inner peripheral edge of the opening formed in the sheet. The brush is passed through the opening with the side of the brush abutting. As a result, when the brush moves on the commutator from a predetermined contact position with respect to the commutator, the sheet bends in the direction in which the brush has moved, so that the restoring force of the sheet acts on the brush, causing the brush to move. Attempts to return to a predetermined position. As a result, as in the case of the first aspect, the movement of the brush near the commutator contact portion is restricted, so that the brush rubs against the inner wall of the brush holder, and the side wall of the brush is worn, and the brush is chipped and broken. Can be avoided.
[0007]
Further, similarly to the first aspect, an effect of avoiding a situation in which an electrical short circuit occurs by receiving abrasion powder of the brush generated by sliding contact with the commutator to some extent by a sheet, and diffusion of the abrasion powder of the brush. Thus, the effect of avoiding the problem of slippage of the bearing portion of the DC motor or the like can be obtained.
[0008]
According to the third aspect of the present invention, the opening area of the opening is smaller than the cross-sectional area of the brush, and, for example, by forming a cut in the inner peripheral edge of the opening, the opening is formed when the brush is inserted through the opening. Since the inner peripheral edge of the portion can be deformed according to the outer peripheral shape of the brush, the outer peripheral surface of the brush can be easily brought into contact with the inner peripheral edge of the opening.
[0009]
According to the fourth aspect of the present invention, since the plurality of openings through which the plurality of brushes can be inserted are provided in the sheet, the movement of the plurality of brushes near the commutator contact portion can be regulated by one sheet. . Also, in this case, the contact portion between the brush and the commutator can be covered over a wider area, so that a situation in which an electrical short circuit occurs by receiving the abrasion powder of the brush with the sheet can be avoided, and the brush can be protected. By suppressing the diffusion of the abrasion powder, the effect of avoiding the problem of poor sliding of the bearing portion or the like can be obtained more reliably.
[0010]
According to the invention of claim 5, the sheet is made of a material made of aromatic polyamide. This makes it possible to obtain a sheet excellent in tear strength, heat resistance, and flexibility, which are characteristics of a material made of an aromatic polyamide, so that the life of the sheet can be extended.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, a brush holding device for a DC motor according to the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view around the brush holding device when the brush holding device of the present invention is applied to a starter motor (hereinafter abbreviated as a motor).
The motor 1 has a cylindrical yoke 4 holding a field pole composed of a field coil 2 and a pole core 3 on its inner peripheral surface, and both ends of a shaft 5 rotatably supported via bearings (not shown) (one end is an end). Armature 7 (supported by frame 6), commutator 8 provided in a cylindrical shape on one end side of shaft 5, brush 9 slidingly contacting this commutator 8, and brush holding device (described later) for holding brush 9 And so on.
[0012]
Hereinafter, the brush holding device will be described. Note that components of the motor 1 other than the brush holding device are very well-known, and a description thereof will be omitted.
The brush holding device is provided with a brush holder 10 (brush holder of the present invention) for accommodating the brush 9, a spring 11 for urging the brush 9 toward the commutator 8, and between the commutator 8 and the brush holder 10. And a thin sheet 12.
[0013]
The brush holder 10 is provided in a cylindrical shape surrounding the outer periphery of the brush 9 and is capable of moving the brush 9 in the cylindrical direction (the vertical direction in FIG. 1) (that is, the outer peripheral surface of the brush 9 and the brush holder 10). (With a predetermined gap between the inner peripheral surface and the inner peripheral surface). As shown in FIG. 2, the brush holder 10 has a plate-like mounting portion 10 a branched from the cylindrical brush holding portion into two branches, and the mounting portion 10 a is fixed to the holder plate 13 with rivets 14. I have. In addition, a recess 10b (see FIG. 1) for taking out the lead wire 15 connected to the brush 9 is provided on one wall surface of the brush holder 10.
[0014]
The holder plate 13 is fixed to an end frame 6 that covers the rear part of the motor 1 with screws or the like (not shown).
The spring 11 is made of a leaf spring. One end of the leaf spring is supported by an end 10 c (see FIG. 2) extending from the mounting portion 10 a of the brush holder 10, and the other end presses the rear end face of the brush 9. Thus, the brush 9 is urged toward the commutator 8 side.
[0015]
The sheet 12 is made of a material made of an aromatic polyamide fiber or the like having relatively excellent tear strength, heat resistance, and flexibility, and is provided in an annular shape along the outer peripheral surface of the commutator 8. The sheet 12 has an opening 12a through which the brush 9 passes, as shown in FIG. The opening 12a has a shape (rectangular in this embodiment) corresponding to the outer peripheral shape of the brush 9, and is provided in such a size that the outer peripheral surface of the brush 9 contacts the inner peripheral edge. Alternatively, a minute gap may be provided between the inner peripheral edge of the opening 12 a and the outer peripheral surface of the brush 9. However, in this case, the clearance between the inner peripheral edge of the opening 12a and the outer peripheral surface of the brush 9 is set to be smaller than the clearance between the outer peripheral surface of the brush 9 and the inner peripheral surface of the brush holder 10.
[0016]
Supporting pieces 12b and 12c for holding the sheet 12 between the commutator 8 and the brush holder 10 are provided on both sides of the sheet 12 in which the opening 12a is formed. One support piece 12b provided only by one is supported by the brush holder 10 by hooking a hole 12d opened in the support piece 12b with a key portion 10d provided on the side surface of the brush holder 10, and two support pieces are provided. The other support piece 12c is sandwiched between the mounting portion 10a of the brush holder 10 and the holder plate 13, and is fixed through the rivet 14 in a previously formed round hole 12e. However, on the side of the positive brush 9 requiring electrical insulation, an insulating plate 16 is interposed between the brush holder 10 and the holder plate 13, and an insulator bush 17 is fitted around the outer periphery of the rivet 14, and the rivet 14 is Electrical insulation with the holder plate 13 is performed (see FIGS. 1 and 2).
[0017]
Next, the operation and effect of the present embodiment will be described.
The brush 9 has a predetermined gap with respect to the brush holder 10 so that the brush 9 can move in the direction of contact and separation with the commutator 8 (the cylinder direction of the brush holder 10). This gap allows the brush 9 to move within the brush holder 10 not only in the direction of contact with and separation from the commutator 8 but also in the direction of rotation of the commutator 8. For this reason, when the starter receives high vibration, for example, when the engine is rotating at high speed, when the starter vibrates due to the vibration of the engine, the brush 9 moves in the brush holder 10 in accordance with the vibration. It shows a behavior of moving on the commutator 8 in the sliding direction.
[0018]
Here, since the brush 9 is inserted through the opening 12a of the sheet 12 between the commutator 8 and the brush holder 10, when the brush 9 moves from a predetermined position on the commutator 8, the brush 9 The sheet 12 bends in the moving direction according to the amount of movement of the brush 9. At this time, the restoring force of the sheet 12 attempts to return the sheet 12 itself to its original state (a state without bending), so that the restoring force of the sheet 12 acts on the brush 9 to return the brush 9 to a predetermined position. To try. As a result, the movement of the brush 9 in the vicinity of the commutator contact portion is restricted, and problems such as side wall wear of the brush 9, chipping and cracking of the brush 9 caused by the collision of the brush 9 with the inner wall of the brush holder 10 are avoided. be able to.
[0019]
Further, during operation of the starter, the brush 9 is in contact with the commutator surface, and when rotated, the brush 9 moves by the gap with the brush holder 10 due to the sliding contact resistance, and rattling of the brush 9 returns. According to the present invention, the rattling is reduced and the rectification performance is improved.
[0020]
Further, since the sheet 12 covers the contact portion between the brush 9 and the commutator 8, the abrasion powder of the brush 9 generated by the sliding contact with the commutator 8 can be received by the sheet 12 to some extent. For this reason, it is possible to avoid a situation in which abrasion powder of the brush 9 is locally deposited inside the motor 1 and an electrical short circuit occurs. Further, the fact that the sheet 12 covers the contact portion between the brush 9 and the commutator 8 also means that the portion where the abrasion powder of the brush 9 is generated is covered, so that the diffusion of the abrasion powder of the brush 9 is suppressed. The effect occurs. This reduces the chance that the abrasion powder of the brush 9 adheres to a portion of the motor 1 that requires slippage, such as the bearing portion of the motor 1, and thus has an effect of avoiding the problem of slippage.
[0021]
(Second embodiment)
FIG. 4 is a perspective view of the seat 12.
In this embodiment, the opening area of the opening 12a opened in the sheet 12 is set smaller than the cross-sectional area of the brush 9, and the cuts 12f are provided at the four corners of the opening 12a (see FIG. 4). In this case, when the brush 9 is inserted into the opening 12a, the inner peripheral edge of the opening 12a can be deformed from the state of FIG. 5 to the state of FIG. The outer peripheral surface of the brush 9 can be easily brought into contact with the inner peripheral edge of the opening 12a without having to adjust the size of the brush 9 to the size (outer peripheral shape) of the brush 9.
[0022]
(Third embodiment)
FIG. 7 is a cross-sectional view around the brush holding device.
This embodiment shows an example in which the commutator 8 is disposed substantially perpendicular to the shaft 5 of the armature 7. Also in this case, the sheet 12 is arranged between the commutator 8 and the brush holder 10, and the brush 9 is inserted through an opening 12 a opened in the sheet 12. In the configuration of the present embodiment, the same effect as in the first embodiment can be obtained.
[0023]
(Modification)
The sheet 12 does not have to be made of the material made of the aromatic polyamide fiber described in the present embodiment as long as it is a flexible thin plate member.
In the first embodiment, the annular sheet 12 has been described along the outer peripheral surface of the commutator 8, but an independent sheet 12 may be provided for each brush.
[Brief description of the drawings]
FIG. 1 is a sectional view around a brush holding device (first embodiment).
FIG. 2 is a view as viewed from A in FIG. 1 (first embodiment).
FIG. 3 is a perspective view of a seat (first embodiment).
FIG. 4 is a perspective view of a seat (second embodiment).
FIG. 5 is a sectional view of a sheet (second embodiment).
FIG. 6 is a sectional view of a sheet showing a state in which a brush is inserted (second embodiment).
FIG. 7 is a sectional view around a brush holding device (third embodiment).
[Explanation of symbols]
1 Motor (DC motor)
8 commutator 9 brush 10 brush holder (brush holder)
12 Sheet 12a Opening

Claims (5)

A brush whose tip surface is in sliding contact with the commutator,
A brush holder for holding the brush,
Interposed between the commutator and the brush holder, a thin sheet having flexibility formed with an opening through which the brush is provided,
The gap between the inner peripheral edge of the opening of the sheet and the outer peripheral surface of the brush is set smaller than the gap between the inner peripheral surface of the brush holder and the outer peripheral surface of the brush. Brush holding device. A brush whose tip surface is in sliding contact with the commutator,
A brush holder for holding the brush,
Interposed between the commutator and the brush holder, a thin sheet having flexibility formed with an opening through which the brush is provided,
A brush holding device for a DC motor, wherein the brush is inserted through the opening with the outer peripheral surface of the brush abutting the inner peripheral edge of the opening of the sheet. The brush holding device for a DC motor according to claim 1 or 2,
In the sheet, the opening area of the opening is smaller than the cross-sectional area of the brush passing through the opening, and when the brush is inserted into the opening, the inner peripheral edge of the opening has an outer peripheral shape of the brush. A brush holding device for a DC motor, which is formed so as to be deformable correspondingly. The brush holding device for a DC motor according to any one of claims 1 to 3,
A brush holding device for a DC motor, wherein the sheet has a plurality of openings through which a plurality of brushes used for the DC motor can be inserted. A brush holding device for a DC motor according to any one of claims 1 to 4,
The brush holding device for a DC motor, wherein the sheet is made of a material made of aromatic polyamide.

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