JP2008178249A - Dc motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a brush holder to surely hold a brush by simplifying the structure of the brush holder. <P>SOLUTION: A DC motor is provided with a cylindrical motor housing 2 having opened one end; an end cap 3 for closing the one end of the motor housing 2; the brush 6 elastically contacting the external circumferential surface of a commutator 5, integrally rotating with a rotary shaft 4 in the motor housing 2; and a printed board 7 mounted with a noise prevention circuit for suppressing the noise. The end cap 3 is provided with a groove-like brush holder 9, having an opening on the side facing the inside of the motor housing and used to slidably hold the brush 6. The printed board 7 is disposed in the motor housing 2 so that its plane can be orthogonal to the axial line direction of the rotary electric machine 4, and the brush 6 slidably held in the brush holder 9 can slide over the plane. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a DC motor including a printed circuit board on which a noise prevention circuit that suppresses noise is mounted.

  In a conventional DC motor, a brush is slidably fitted in a brush holder portion attached to one end of a motor housing, and this brush is elastically applied to the outer peripheral surface of a commutator that rotates integrally with a rotating shaft. (See, for example, Patent Document 1).

Some have a printed circuit board on which a noise prevention circuit is mounted so that noise generated from the energized portion of the brush and the commutator does not adversely affect other circuits during rotation of the rotating shaft (for example, , See Patent Document 2).
JP-A-10-201183 Japanese Patent Laid-Open No. 7-135752

  However, in the DC motor described in Patent Document 1 described above, the brush is moved to the brush holder portion by the influence of the sliding resistance between the brush and the commutator and the unevenness of the commutator as the rotating shaft rotates. Since the brush holder part has a rectangular cylindrical shape penetrating in the radial direction so as not to fall off from the brush, there is a problem that the assembly of the brush to the brush holder part is troublesome and the structure of the brush holder part is complicated. is there.

In the DC motor described in Patent Document 2, since the noise prevention circuit is mounted on the outside of the motor housing together with the printed circuit board, there is a problem that the external dimension of the motor itself, particularly the dimension in the axial direction of the rotating shaft becomes large.

  SUMMARY OF THE INVENTION In view of the above-described conventional problems, an object of the present invention is to provide a DC motor in which the configuration of the brush holder portion is simplified and the brush can be reliably held on the brush holder portion. .

According to the present invention, the above problem is solved as follows.
(1) A cylindrical motor housing with one end open, an end cap that closes one end of the motor housing, and a brush that elastically contacts the outer peripheral surface of a commutator that rotates integrally with the rotating shaft in the motor housing. And a DC motor including a printed circuit board on which a noise prevention circuit for suppressing noise is mounted. The end cap has a groove-like shape opened on the side facing the interior of the motor housing for slidably holding the brush. A brush holder portion is provided, and the printed circuit board has a plane perpendicular to the axial direction of the rotation shaft, and the brush held slidably on the brush holder portion can slide on the plane. Place in the motor housing.

(2) In the above item (1), the printed circuit board is provided with a circular opening through which the commutator penetrates together with the rotating shaft, and the noise prevention circuit is arranged around the commutator.

(3) In the above (1) or (2), the noise prevention circuit and the printed wiring are not provided on the plane of the printed board facing the brush.

(4) In any one of the above items (1) to (3), the printed circuit board is fixed to an inner portion of the end cap facing the inside of the motor housing.

(5) In any one of the above items (1) to (4), the printed board is provided with an opening through which an electric wire for electrically connecting the brush and the printed board can be inserted.

According to the present invention, the following effects can be achieved.
According to the invention of claim 1, the configuration of the brush holder portion is simplified, the brush can be securely held in the brush holder portion, and the printed circuit board on which the noise prevention circuit is mounted is provided in the motor housing. The direct current motor can be reduced in size.

  According to the second aspect of the present invention, the printed circuit board can be arranged around the commutator in the motor housing without dividing the printed circuit board, and the noise prevention circuit is arranged around the commutator, that is, between the commutator and the brush. It can arrange | position in the vicinity of an electricity supply part, and can remove a noise effectively.

  According to the invention described in claim 3, since the brush does not interfere with the noise prevention circuit and the printed wiring, the brush can be smoothly slid and the noise prevention circuit and the printed wiring can be prevented from being damaged.

  According to the fourth aspect of the present invention, the printed circuit board can be securely held in the motor housing.

  According to invention of Claim 5, a brush and a printed circuit board can be electrically connected easily via an electric wire.

  FIG. 1 is a longitudinal sectional view of a main part of the DC motor 1, and FIG. 2 is a longitudinal sectional view taken along line II-II in FIG. Note that left and right in FIG. 1 are “left and right”, and left and right in FIG. 2 are “front and back”.

  The DC motor 1 includes a motor housing 2 formed of a metal such as iron having a closed front end and an open rear end, and a synthetic resin end that closes the rear end of the motor housing 2. Cap 3, commutator 5 that rotates together with rotating shaft 4 that is pivotally supported in motor housing 2, two brushes 6 that are elastically pressed against the outer peripheral surface of commutator 5, and commutation with brush 6 It is configured to include a printed circuit board 7 and the like on which electric components (to be described later) constituting a noise prevention circuit that suppresses noise generated from a current-carrying portion with the child 5 is mounted.

A permanent magnet (not shown) is attached to the inner peripheral surface of the motor housing 2, and the motor housing 2 and the permanent magnet constitute a stator.

  The front end portion of the rotating shaft 4 is pivotally supported by a front end side of the motor housing 2 via a bearing (not shown), and the rear end portion is also a boss portion 31 provided at the center portion of the end cap 3. Are pivotally supported via bearings 8.

  An armature (not shown) in which a winding is wound around an iron core is attached to the rotating shaft 4, and the commutator 5, the rotating shaft 4, and the electric machine are connected by electrically connecting the armature winding to the commutator 5. The child constitutes a rotor accommodated in the motor housing 2.

  The end cap 3 is integrally molded of a synthetic resin material, and brush holder portions 9 and 9 for slidably holding the brush 6 are integrally formed on a front surface thereof, that is, an inner surface facing the inside of the motor housing 2. Is formed. Further, brushes 6 and 6, springs 10 and 10 for biasing the brushes 6 and 6 toward the outer peripheral surface of the commutator 5, and a printed circuit board 7 on which a noise prevention circuit is mounted are assembled on the inner surface of the end cap 3. It has been. A connector portion 32 provided with a terminal 33 that is electrically connected to a power source is provided on the outer upper portion of the end cap 3, and the power source is connected to the brush through the terminal 33 and an electrical component mounted on the printed circuit board 7. 6 is supplied.

  The brushes 6 and 6, the springs 10 and 10, and the printed circuit board 7 are assembled to the end cap 3 in advance before the end cap 3 is attached to the motor housing 2.

  Since the lower and right brushes 6, the brush holder portion 9 and the vicinity thereof have the same shape, only the lower portion will be described below.

  The brush holder portion 9 is provided with a pair of left and right side walls 92 and 92 projecting forward on the left and right sides of the sliding surface 91 extending in the radial direction and facing forward. It has a substantially U-shaped groove shape with an open cross-sectional shape. Thereby, the brush holder part 9 can be made into a simple groove-like configuration, and the brush 6 can be easily assembled to the brush holder part 9 from the front side of the end cap 3.

  The brush 6 is slidably fitted between the side walls 92, 92 of the brush holder portion 9 so that the tip portion can be slidably contacted with the outer peripheral surface of the commutator 5, and the rear surface thereof is in contact with the sliding surface 91. The front surface is slidably brought into contact with a flat surface on the rear side of the printed circuit board 7 fixed to the end cap 3 as described later.

As described above, the brush 6 is slidably sandwiched between the printed circuit board 7 and the brush holder portion 9, so that the sliding resistance between the brush 6 and the commutator 5 with the rotation of the rotating shaft 4. Even if vibrations or shocks in the direction of dropping from the brush holder portion 9 (forward) are applied to the brush 6 due to the influence of the unevenness of the commutator 5 or the like, the movement of the brush 6 in that direction is suppressed by the printed circuit board 7. Therefore, the brush 6 can be reliably held on the brush holder portion 9.

  A pigtail 11 that is electrically connected to the printed circuit board 7 and includes a flexible electric wire that supplies current to the brush 6 is implanted on the front surface of the brush 6 near the head.

  The printed circuit board 7 is disposed on the front surface of the end cap 3 in the motor housing 2 so that the plane thereof is orthogonal to the axial direction (front-rear direction) of the rotating shaft 4 and the front surface of the brush 6 can be slidably contacted with the rear surface. Fixed. Specifically, by projecting forward projections 34, 34 provided on the front surface of the end cap 3 into mounting holes 73, 73 provided in the printed circuit board 7, and caulking the front end thereof, The printed circuit board 7 is fixed to the end cap 3.

  On the printed circuit board 7, a noise prevention circuit including a capacitor 12, a diode 13, a resistor 14, two choke coils 15, an overcurrent limiting element 16 that limits overcurrent, and a rotational speed of the rotary shaft 4 are detected. Electrical components such as the Hall element 17 are mounted. Note that all electrical components and printed wiring including the noise prevention circuit are provided outside the region located around the commutator 5 and facing the front surfaces of the brushes 6 and 6. That is, on the plane of the printed circuit board 7 facing the brushes 6 and 6, all the electrical components including the noise prevention circuit and the printed wiring are not provided at all. The noise prevention circuit is not specified in the present embodiment, and can be variously changed based on a known technique.

In the center of the printed circuit board 7, a circular opening 71 through which the commutator 5 penetrates together with the rotating shaft 4 is provided. Thereby, the printed circuit board 7 can be arrange | positioned around the commutator 7 in the motor housing 2 without dividing | segmenting, and a noise prevention circuit can be provided in the periphery vicinity of the commutator 7. FIG. In addition, an opening 72 through which the pigtail 11 can be inserted is provided in a part of a region of the printed board 7 facing the front surface of the brush 6. Accordingly, the brush 6 and the printed board 7 can be easily electrically connected by passing the pigtail 71 through the opening 72.

As described above, by providing the noise prevention circuit in the motor housing 2 together with the printed circuit board 7, it is possible to reduce the size of the motor 1, in particular, to shorten the length in the axial direction. Further, by arranging the noise prevention circuit around the commutator 5, that is, in the vicinity of the energized portion between the commutator 5 and the brush 6, noise generated from the energized portion between the brush 6 and the commutator 5 is effectively removed. be able to. Furthermore, since the electrical components and the printed wiring are provided outside the area facing the front surfaces of the brushes 6 and 6 of the printed circuit board 7, the brush 6 does not interfere with the noise prevention circuit and the printed wiring. Can be made smooth, and the noise prevention circuit and the printed wiring can be prevented from being damaged.

It is a longitudinal cross-sectional view of the motor to which one Embodiment of this invention is applied. It is the II-II line longitudinal cross-sectional view in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC motor 2 Motor housing 3 End cap 4 Rotating shaft 5 Commutator 6 Brush 7 Printed circuit board 8 Bearing 9 Brush holder part 10 Spring 11 Pigtail (electric wire)
12 Capacitor (Noise prevention circuit)
13 Diode (Noise prevention circuit)
14 Resistor (Noise prevention circuit)
15 Choke coil (noise prevention circuit)
16 Overcurrent limiting element 17 Hall element 31 Boss part 32 Connector part 33 Terminal 34 Projection part 71 Opening part 72 Opening part 73 Mounting hole 91 Sliding surface 92 Side wall

Claims (5)

A cylindrical motor housing with one end open, an end cap that closes one end of the motor housing, a brush that elastically contacts the outer peripheral surface of the commutator that rotates together with the rotating shaft in the motor housing, and noise In a DC motor equipped with a printed circuit board mounted with a noise prevention circuit that suppresses
The end cap is provided with a groove-shaped brush holder portion that is open on the side facing the inside of the motor housing for slidably holding the brush, and the plane of the printed board is the axial direction of the rotating shaft. The DC motor is arranged in the motor housing so that the brush that is slidably held by the brush holder portion on the plane thereof can slide on the plane. 2. The DC motor according to claim 1, wherein the printed circuit board is provided with a circular opening through which the commutator penetrates together with the rotating shaft, and the noise prevention circuit is arranged around the commutator. 3. The DC motor according to claim 1, wherein the noise prevention circuit and the printed wiring are not provided at all on a plane of the printed board facing the brush. The DC motor according to any one of claims 1 to 3, wherein the printed circuit board is fixed to an inner portion of the end cap facing the inside of the motor housing. 5. The DC motor according to claim 1, wherein the printed board is provided with an opening through which an electric wire for electrically connecting the brush and the printed board can be inserted.

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