JP2001238408A - Dc motor with brush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC motor having brushes, capable of preventing uneven wears of brushes by preventing inclination of a coiled spring by simple constitution, and allowing smooth movements of the brushes in the motor with the brushes for containing a brush holder for holding a plurality of the brushes, contacted slidably with a commutator of a rotor in a bracket, by axially supporting one end side of the rotor to the bracket mounted at one end of a stator case for holding a stator. SOLUTION: The brush holder has a discoidal insulating board having a circular hole for passing a rotor shaft at a center, a plurality of brush-containing cases made of a sheet metal fixed at an equal interval circumferentially to the board and having a brush holder opened toward a radial inside, the brushes contained in the respective claws, a substantially perpendicular coiled spring holding claw to the board and formed at a side of the holder by bending a metal as a part of the cases, and a torsion coil spring held at the pawl and engaged with brushes at one end to press the brushes to radially inward side. In this case, the claw is twisted around a torsion axis of the coiled spring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushed DC motor for pressing a brush with a torsion coil spring.

[0002]

2. Description of the Related Art In a vehicle engine such as an automobile or a motorcycle, a DC motor with a brush is widely used as a motor for starting the engine. In this motor, a commutator is provided on a rotor, and a brush is held on a motor case side.
Here, the brush is pressed toward the commutator by a spring so as to elastically contact the commutator.

That is, the brush is held by a brush holder so as to be movable inward in the radial direction of the rotor, and the brush is elastically pressed inward (toward the center axis of the rotor) by a spring attached to the brush holder. I do.

[0004] Such a brush holder has a disk-shaped insulating substrate through which a rotor shaft passes, a brush storage box, and a brush stored in the brush storage box, and uses the brush with the torsion force (torsion force) of a torsion coil spring. ) Is known for pressing against a commutator.

FIG. 8 is an exploded perspective view of a brush storage box according to an embodiment of the present invention, as will be described later. Here, the structure of the conventional apparatus is shown by phantom lines. (A) of FIG.
11 (B) and FIGS. 11 (A) and 11 (B) are a plan view and a front view showing an ideal operation state and an actual operation state of the conventional device, respectively, in partial cross section.

[0006] As shown in FIG.
It includes an insulating substrate 36, a brush storage box 38, and a brush 40. The brush storage box 38 is formed by a metal plate 42 and a frame plate 44. The metal plate 42 is formed with a stopper 48 standing upright on the side of the frame plate 44 and a coil spring holding claw 50A. Here, in the conventional device, the coil spring holding claw 50A
Has a rectangular cross section as shown by a virtual line in FIG. 8, and its long side is parallel to the direction in which the brush 40 moves forward and backward.

The torsion coil spring 52 is held by the holding claw 50A with its central axis, that is, the torsion axis T superimposed on the holding claw 50A. One end 5 of the coil spring 52
2a is locked by a stopper 48, and the other end 52b is
The brush 40 faces the inside of the frame plate 44 from the long window 54 formed in the above and presses the brush 40 from the back.

In this conventional apparatus, if the coil spring 52 is held by the holding claw 50A in an ideal state, the coil spring 52 shown in FIG.
(A), (B), both ends 52 of the coil spring 52
a, 52b are in the correct position with the stopper 48 and the brush 4
0 engages the back. However, in practice, the coil spring 52 is greatly inclined with respect to the holding claw 50A as shown in FIGS. That is, the lower part of the coil spring 52 (the substrate 3
6 and the right side (frame plate 44) in FIGS. 10 and 11 by the reaction force of the stopper 48 acting on one end 52a of the coil spring 52.
Side). On the other hand, the upper part of the coil spring 52 is pushed leftward in FIGS. 10 and 11 by the reaction force of the brush 40 acting on the other end 52 b of the coil spring 52.

As a result, the coil spring 52 is inclined as shown in FIG.
b comes into contact with the back surface of the brush 40 at an angle. The contact position of the other end 52b with the back surface of the brush 40 also moves upward as shown in FIG. As a result, the brush 40 is inclined and pressed, so that smooth movement becomes impossible or uneven wear of the brush 40 occurs.

The present invention has been made in view of such circumstances, and it is possible to prevent the coil spring from inclining by an extremely simple configuration, enable smooth movement of the brush, and unevenly wear the brush. It is an object of the present invention to provide a brushed DC motor capable of preventing the occurrence of the DC motor.

[0011]

According to the present invention, an object of the present invention is to provide a plurality of brackets mounted on one end of a stator case for holding a stator, wherein one end of the rotor is pivotally supported, and a plurality of the brackets slidably contact the commutator of the rotor in the bracket. In a DC motor with a brush accommodating a brush holder for holding a brush, the brush holder has a disk-shaped insulating substrate having a circular hole in the center through which a rotor shaft passes, and is fixed to the insulating substrate at equal intervals in a circumferential direction, and in a radial direction. By bending a plurality of sheet metal brush storage boxes having brush holding portions that open inward, brushes stored in each brush storage box, and a metal plate that is a part of the brush storage box, A coil spring holding claw formed on the side of the brush holding portion and substantially perpendicular to the insulating substrate; one end held by the coil spring holding claw and associated with the brush; And a torsion coil spring for pressing the brush radially inwardly, and the coil spring retaining claws is accomplished by brushed DC motor, characterized by being twisted in torsion axis line of the coil spring.

It is desirable that the coil spring holding claw has its root side substantially parallel to the brush projecting direction (moving direction) and its distal end side twisted so as to be substantially perpendicular to this direction. This is particularly effective in preventing the coil spring from tilting when the upper part of the coil spring is pressed by the brush.

The brush storage box can be formed of a metal plate that is in close contact with the insulating substrate and a frame plate that is fixed to the metal plate and that forms a brush holding portion that opens toward the inside in the radial direction. In this case, if the coil spring holding claws are formed integrally with the metal plate, there is no need to separately attach the holding claws, and the number of parts is small and the configuration is simple. It is preferable that a long window is formed in the frame plate so that one end of the coil spring enters the brush holding portion and presses the brush. It is preferable that a stopper for engaging the end of the coil spring opposite to the brush is integrally formed with the metal plate.

[0014]

FIG. 1 is a side view partially showing a starter motor of an engine according to an embodiment of the present invention, FIG. 2 is a front view thereof, FIG. 3 is a view showing the inside of a front bracket, and FIG. 3, FIG. 5 is a front view of the brush holder, FIG. 6 is a side view of the same, FIG. 7 is a perspective view showing a terminal mounted state, FIG. 8 is a partially exploded perspective view of the brush holder, and FIG. (A) and (B) are the top view and front view which show the pressing state of the brush by the coil spring in partial cross section.

In FIGS. 1 and 2, reference numeral 10 denotes a cylindrical stator case. A stator (field, stator) 12 made of a permanent magnet is fixed to the inner peripheral surface of the stator case 10 by an adhesive. I have. The stator 12 is magnetized so as to form a plurality of magnetic pole pairs.

A rear bracket 14 is provided at one end (rear end) of the stator case 10, and a front bracket 16 is provided at the other end (front end).
These brackets 14 and 16 are fixed to the stator case 10 by two long bolts 18 passing outside the stator case 10 after the rotor 20 and a terminal 60 to be described later are assembled inside. Rear bracket 14
Is integrally formed with a mounting portion 14A for fixing to the vehicle body side.

The rotor 20 has a rotor winding wound around a rotor core 24 fixed on a rotor shaft 22. The rotor winding is connected to a commutator 26. One end (rear end) of the rotor shaft 22 is supported by the rear bracket 14 with a bearing 28, and the other end (front end) of the rotor shaft 22 penetrates the front bracket 16, and is supported by the front bracket 16 by a bearing 30. In FIGS. 1 and 4, reference numeral 32 denotes a sealing material.

A brush holder 34 is mounted inside the front bracket 16. The brush holder 34 is a disk-shaped insulating substrate 3 having a circular hole at the center through which the rotor shaft 22 passes.
6 and four brush storage boxes 38 fixed to the insulating substrate 36, and brushes 40 stored in brush holding portions formed in the brush storage boxes 38. As shown in FIG. 8, the brush storage box 38 has a metal plate 42 and a frame plate 44 integrally fixed to a substrate 36. That is, the frame plate 4
Reference numeral 4 denotes four claws 46 which are bent in a substantially U-shape so that both ends are opened in the radial direction and protrude from an edge facing the metal plate 42.
Is penetrated through the metal plate 42 and the substrate 36, and the claws 46 are bent on the back side of the substrate 36 to integrate them.

A coil spring stopper 48 is provided on the metal plate 42.
The coil spring holding claw 50 and the coil spring holding claw 50 are integrally formed so as to stand on the substrate 36. A coil spring 52 for holding the brush is mounted on the coil spring holding claw 50. That is, as shown in FIG. 8, one end 52a of the coil spring 52 is engaged with the spring stopper 48 so that the spring holding claw 50 passes on the center line (torsion axis) T, and the other end 52b is framed. It faces the long window 54 formed in the plate 44. Here, the long window 54 is open on the outer peripheral side of the substrate 36. As shown in FIG. 8, the brush 40 is moved from the center side of the substrate 36 (the center axis side of the rotor shaft 22)
And presses the other end 52 b of the coil spring 52 facing the long window 54.

In actual assembly, the coil spring 5
The other end 52b of the second member is hung on a projection 54a (FIG. 8) provided at an open portion of the long window 54 provided on the frame plate 44, and the brush 40 is loaded into the frame plate 44 in this state. Figure 3,
5 and 6 show a state in which the other end 52b of the coil spring 52 is hooked on the projection 54a. Then, the brush holder 34 in this state is fixed in the front bracket 16.
The brush holder 34 is fixed to the front bracket 16 by two screws 58 (FIG. 3) with the substrate 36 abutting on a support foot 56 (FIG. 4) projecting into the front bracket 16.
The connection wiring 74 fixed to the brush 40 is guided to the outside from the notch 44a (FIGS. 3, 5, and 8) formed on the upper surface of the frame plate 44, and is connected to the terminal plate 70 and the screw 58.

Reference numeral 60 denotes a terminal. Terminal 60
Has a block 62 made of an insulating hard resin or the like, and a terminal plate 64 penetrating the block 62.
The block 62 includes a press-fit portion 62 a having a circular cross section and a flange portion 6.
2b, and the press-fitting portion 62a is press-fittable into a terminal mounting hole 66 penetrating through the front bracket 16 in the radial direction and can be fixed. At this time, the flange portion 62b is in close contact with the outer edge of the terminal mounting hole 66. Note that an O-ring 68 is mounted between the terminal mounting hole 66 and the press-fitting portion 62a to provide a liquid-tight seal (FIG. 4).

The terminal plate 64 is made of a thick metal plate such as a copper alloy having good conductivity, and passes through the inside of the block 62 and has an inner end 64 a protruding into the front bracket 16. The inner end 64a is located closer to the opening of the front bracket 16 than the substrate 36 of the brush holder 34, and has a rectangular cross section (see FIG. 7). The terminal plate 64 is oriented so that its wide surface is parallel to the central axis of the rotor 20.

A terminal plate 70 is soldered to the inner end 64a of the terminal plate 64. This terminal plate 70 is shown in FIG.
As is clear from 4, 7 and the like, a long metal plate having a narrow width and a long groove 72 formed in a longitudinal direction from one end thereof. The width of the long groove 72 is the inner end 64 of the terminal plate 64.
The width is substantially the same as or slightly wider than the width a. The depth of the long groove 72 is
The distance from the surface of the substrate 36 of the brush holder 34 to the upper edge of the inner end 64a (the edge far from the surface of the substrate 36) is larger.

The terminal plate 70 is formed such that the long groove 72 is formed at the inner end 64a.
And soldered to the inner end 64a with the tip pressed against the substrate 36 of the brush holder 34. The connection wiring 74 of the brush 40 is soldered to the other end of the terminal plate 70, that is, the end on the opening side of the front bracket 16. In this embodiment, since four brushes 40 are provided, the two brushes 40 facing each other are connected to the terminal plate 70 by connection wirings 74, respectively. Note that the other two brushes 40
The aforementioned screw 58 (FIG. 3), that is, the brush holder 3
4 is connected to a screw 58 for fixing the fourth substrate 36 to the front bracket 16 by a connection wiring 76 (FIG. 3). In other words, the body is earthed.

After attaching the brush holder 34 to the front bracket 16 and wiring the terminals 60 and the brushes 40 in this manner, the rotor shaft 22 of the rotor 20 is passed through the bearing 30 of the front bracket 16. Then, with the commutator 26 positioned inside the brush holder 34, the coil spring 5
The other end 52 b of the second member is brought into contact with the brush 40. That is, as shown in FIGS. 3 and 5, the other end 52b of the coil spring 52 is held in a state of being engaged with the projection 54a of the frame plate 44 of the brush storage box 38, and the rotor 20 is assembled in this state. Later, the other end 52b of the coil spring 52 is connected to the projection 5 of the frame plate 44.
The brush 40 is released from the window 4a, is inserted into the long window 54, and is engaged with the end face of the brush 40 (the end face far from the commutator 26, that is, the back face). As a result, the brush 40 is pressed against the commutator 26 by the torsion spring force of the coil spring 52.

As described above, the rotor 20 is connected to the front bracket 16.
The rotor 20 is put into the stator case 10 and the end of the rotor shaft 22 is fitted into the bearing 28 of the rear bracket 14. Then, the front and rear brackets 14, 16 may be fastened and fixed to the stator case 10 by the long bolts 18. Finally, the external connection line 78 is screwed to the terminal plate 64 of the terminal 60, and the terminal 60 is covered with the dust cover 80 (FIGS. 1 and 2).

As shown in FIG. 8, the coil spring holding claw 50 has its tip side twisted by approximately 90 ° with respect to the root side. That is, the base of the holding claw 50 is the brush 4
While the direction is almost parallel to the forward / backward movement direction of 0, the tip side is substantially orthogonal. By twisting the holding claw 50 in this manner, the coil spring 52 can be prevented from tilting.

FIG. 9 shows the operation of the coil spring 52. As is clear from FIG. 9A, the lower part of the coil spring 52 (one end 52a side) is displaced with respect to the stopper 48. This can be prevented at the base of the holding claw 50. Further, as is clear from FIG. 9B, the upper end (the other end 52 b side) of the coil spring 52 can be prevented from being separated from the brush 40 by the tip of the holding claw 50. As a result, the coil spring 52 is prevented from tilting, and the brush 40 is always pressed by the coil spring 52 in a correct state.

In this embodiment, the holding claw 50 is twisted by about 90 °, but the twisting angle may be within 90 ° or 90 ° or more, and the shape of the coil spring 52, the engagement position with the brush 40 and the stopper 48, etc. In consideration of this, the optimum torsion angle and shape should be determined.

In this embodiment, the terminal plate 70 fixed to the inner end 64a of the terminal 60 is provided with an elongated hole as an example.
A substantially vertical long groove 72 was formed in the substrate 36 of the brush holder 34. Therefore, the inner end 6 of the terminal 60 is
By pressing the terminal plate 70 against the substrate 36 with the 4a engaged, and soldering the terminal plate 70 to the inner end 64a in this state, the edge of the terminal plate 70 can be strongly pressed against the substrate 36. Therefore, the rotation of the terminal plate 70 and the terminal plate 64 integrated therewith can be reliably restricted.

The contact portion between the terminal plate 70 and the substrate 36 of the brush holder 34 is preferably fixed with an adhesive or the like. By doing so, the terminal plate 70 and the substrate 36 are integrated, and the rotation of the terminal plate 70 and the terminal 60 can be more reliably prevented.

[0032]

As described above, according to the present invention, when the brush of the brush holder is pressed by the torsion coil spring, the holding plate for holding the coil spring is formed by bending the metal plate which becomes a part of the brush storage box. , And the holding claws are twisted around the torsion axis of the coil spring, so that the coil spring is less likely to tilt with respect to the holding claws.

Therefore, the coil spring can be prevented from tilting due to the reaction force when pressing the brush, and the coil spring can always press the brush in a correct state. Therefore, smooth operation of the brush becomes possible. In addition, the wear of the brush does not become uneven, the durability of the brush is improved, and the reliability of the motor is improved.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional side view of an engine starter motor according to an embodiment;

FIG. 2 is also a front view

FIG. 3 is a diagram showing the inside of a front bracket.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a front view of the brush holder.

FIG. 6 is a side view of the same.

FIG. 7 is a perspective view showing a terminal mounting state.

FIG. 8 is a partially exploded perspective view of a brush holder.

FIG. 9 is a diagram illustrating the operation of a coil spring.

FIG. 10 is a diagram showing an actual operation state of a coil spring in a conventional device.

FIG. 11 is a diagram showing an actual operation state of a coil spring in a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Stator case 14 Rear bracket 16 Front bracket 20 Rotor 26 Commutator 34 Brush holder 36 Insulating board 38 Brush storage box 40 Brush 42 Metal plate 44 Frame plate 48 Stopper 50, 50A Coil spring holding claw 52 Coil spring T Torsion axis

Claims (4)

[Claims] 1. A bracket attached to one end of a stator case for holding a stator, which rotatably supports one end of a rotor, and accommodates a brush holder for holding a plurality of brushes slidingly contacting a commutator of the rotor in the bracket. In the DC motor with a brush, the brush holder has a disk-shaped insulating substrate having a circular hole through which a rotor shaft passes in a center, and a brush holding portion fixed to the insulating substrate at equal intervals in a circumferential direction and opening inward in a radial direction. A plurality of sheet metal brush storage boxes, brushes respectively stored in the brush storage boxes, and a metal plate which is a part of the brush storage box formed by bending a metal plate on a side of the brush holding portion. A coil spring holding claw substantially perpendicular to the insulating substrate, one end of which is held by the coil spring holding claw and engages the brush to push the brush radially inward; Torsion coil springs, wherein the brush DC motor, wherein a coil spring retaining claws are twisted in torsion axis line of the coil spring. 2. The brush-equipped DC motor according to claim 1, wherein the holding claw has a base side substantially parallel to the brush reciprocating direction and a tip side substantially orthogonal to the brush reciprocating direction. 3. The brush storage box is formed of a metal plate that is in close contact with the insulating substrate, and a frame plate that is fixed to the metal plate and that forms a brush holding portion that opens radially inward. 3. The brushed DC motor according to claim 1, wherein the DC motor is formed integrally with a metal plate. 4. The brushed DC motor according to claim 3, wherein a long window is formed in the frame plate so that one end of the coil spring enters the brush holding portion and presses the brush.