JP3191105B2 - DC motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC motor for mechanically sliding a power supply brush against a commutator, and more particularly to a structure for fixing a brush holder to a lid.

[0002]

2. Description of the Related Art Conventionally, as a DC motor of this type used in automobiles and the like, a power supply brush is attached to a brush holder made of synthetic resin, and this brush holder is attached to a metal lid covering an opening of a case. What fixed using a metal piece is known.

FIG. 6 is a sectional view taken along line VI-VI of FIG. 7 showing a conventional example of such a DC motor, FIG. 7 is a side view of the motor, and FIG. 8 is a perspective view of a metal piece. In these drawings, a DC motor 1 is rotatably supported by a housing 4 composed of a bottomed cylindrical case 2 and a lid 3 and two bearings 5A and 5B incorporated in the housing 4. The rotating shaft 6, an armature 7 and a commutator 8 mounted on the rotating shaft 6, and a plurality of magnets 9 fixed to the inner peripheral surface of the case 2 so as to surround the outer periphery of the armature 7. Have. In addition, the commutator 8
There are provided two power supply brushes 10 slidingly contacting the outer peripheral surface of the armature 7, and power is supplied to the winding 11 of the armature 7 by mechanical sliding contact between the power supply brushes 10 and the commutator 8.

The two power supply brushes 10 are held in a brush mounting portion 13 of the brush holder 12 so as to be able to advance and retreat in the radial direction of the commutator 8 so as to face the brush holder 12 with the commutator 8 interposed therebetween. The spring 14 is pressed against the outer peripheral surface of the commutator 8. The brush holder 12 is made of a synthetic resin, and is formed integrally with the three mounting metal pieces 15 by insert molding. The power supply brush 10
Is connected to the terminal 17 via a lead wire (not shown).

The metal piece 15 is formed in an L-shape as shown in FIG. 8 by punching and bending. That is, the buried-side end portion 15a buried in the brush holder 13 is bent at a substantially right angle to prevent the brush holder 12 from coming off from the brush holder 12, thereby forming a break-through preventing portion. On the other hand, the end 15b opposite to the buried side end 15a protrudes outside the brush holder 12 as shown by a two-dot chain line in FIG. 6, and when the brush holder 12 is fixed to the lid 3,
The cover 3 is inserted into the locking hole 16 provided on the cover 3 from the back side of the cover 3 and protrudes toward the front side.
The brush holder 12 is bent toward the side opposite to the bending direction of 5 a and pressed against the surface of the lid 3 so that the brush holder 12 is
It is fixed to.

[0006]

As described above, the conventional DC motor 1 has a metal piece 1 embedded in a brush holder 12.
The brush holder 12 is fixed to the lid 3 by inserting and bending the protruding end 15 b of the fifth 5 into the locking hole 16 provided in the lid 3. However, such a fixing structure of the brush holder 12 employs a structure in which the lid 3 is sandwiched between the brush holder 12 and the metal piece 15. There is a problem that a gap is generated and the reliability of mounting the brush holder 12 is reduced. That is, the protruding end 15 of the metal piece 15
When b is bent, the brush holder 12 is pressed against the back surface of the lid 3, and a certain distortion is generated. Further, the brush holder 12 tends to expand due to an increase in the ambient temperature, but cannot actually expand because the brush holder 12 is restrained by the lid 3 and the metal piece 15, and the distortion further increases, and the stress increases with time. Decreases (stress relaxation). Then, when the temperature returns to normal temperature, it shrinks and the thickness decreases, and a gap is generated between the lid 3 and the brush holder 12. As a result, the brush holder 1
2 rattles and generates noise. In particular, the rattling of the brush holder 12 due to such stress relaxation is fatal in a motor disposed in an engine room where the temperature rises and falls remarkably, for example, a motor for an actuator that controls opening and closing of a throttle valve. Become.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to surely prevent rattling of a brush holder due to stress relaxation and to provide a reliable mounting of the brush holder. An object of the present invention is to provide a DC motor with improved performance.

[0008]

According to a first aspect of the present invention, a housing for accommodating a brush holder, a rotating shaft, a magnet, and the like, to which a power supply brush is attached, has a cylindrical case, and a housing for the case. A cover covering the opening, and inserting a protruding end of a metal piece embedded in the brush holder into a locking hole of the cover and bending the brush holder to fix the brush holder to the cover. In the motor, an embedded plate portion embedded in the brush holder, one end surface of which is exposed to the surface of the brush holder and comes into contact with the back surface of the lid, and the lid integrally protruded from the one end surface of the embedded plate portion. The metal piece is formed by a fixing piece inserted into the locking hole and bent.

[0009] The second invention is the above-mentioned first invention, wherein:
It is characterized in that the metal piece is formed in a flat plate shape, and a removal prevention portion for preventing the removal from the brush holder is formed in the buried plate portion, and the brush holder is formed integrally with the metal piece.

[0010] In the present invention, since the lid is sandwiched between the one end face of the buried plate portion of the metal piece and the fixing piece, it is assumed that a gap is generated between the brush holder and the lid due to the thermal contraction of the brush holder. However, the metal piece itself does not rattle against the lid. Therefore, rattling of the brush holder can be prevented. Since the metal piece is formed in a flat plate shape, it can be easily formed by press working, laser processing, or the like, and does not require a bending step. The removal prevention portion of the brush holder prevents the metal piece from falling out of the brush holder.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a cross-sectional view taken along line II of FIG. 2 showing an embodiment of a DC motor according to the present invention.
FIG. 2 is a side view of the motor, and FIGS. 3A and 3B are a front view and a side view of a metal piece. Components equivalent to those shown in the section of the prior art are denoted by the same reference numerals, and description thereof will be omitted as appropriate. In these drawings, a DC motor 20 includes a housing 4 that houses a rotating shaft 6, a magnet 9, a power supply brush 10, and the like. The housing 4 includes a cylindrical case 2 formed of a ferromagnetic material such as iron, and a lid 3 also formed of iron or the like and covering an opening of the case 2. Has been fixed.

The rotary shaft 6 is provided with an armature 7 and a commutator 8, and is rotatably supported by two bearings 5A and 5B. The power supply brush 10
Are arranged so as to face each other with the commutator 8 interposed in a brush mounting portion 13 provided on the brush holder 12, and are pressed against the outer periphery of the commutator 8 by a coil spring 14.

The brush holder 12 has a hole 21 in the center through which the rotating shaft 6 penetrates, the brush mounting portion 13 is formed on the brim of the commutator 8, and the bearing is formed on the brim of the lid 3. A recess 22 into which 5B fits is formed. Such a brush holder 12 is made of synthetic resin, is formed integrally with three metal pieces 23 by insert molding, and is fixed to the back surface of the lid 3 by these metal pieces 23. At the time of molding, as shown in FIGS. 4A and 4B, a projection 25 having a groove 26 for holding the lower end of the metal piece 23 is formed on a lower mold 24B constituting the mold 24 together with the upper mold 24A.
Is provided, the metal piece 23 can be held in a stable state. In addition, on the lower surface side of the brush holder 12,
A hole 27 for the projection 25 is formed.

The metal piece 23 is desirably embedded in the brush holder 12 by punching a metal plate having the same material or a thermal expansion coefficient substantially equal to that of the lid 3. Horizontal rectangular buried plate part 2
3A and a fixed piece 23B integrally protruding from the center of one end face 30 of the buried plate portion 23A. The embedded plate portion 23A is embedded in the brush holder 12 so that the one end surface 30 is exposed on the surface of the brush holder 12 and forms the same plane. The buried plate portion 23A is formed with a hole 31 and a semicircular concave portion 32, respectively, serving as a removal prevention portion for preventing the removal from the brush holder 12. The hole 31 is formed in the center of the buried plate portion 23A, and the concave portions 32 are formed on both side surfaces. If the hole 31 and the concave portion 32 are formed in this way, the molten resin enters the hole 31 and the concave portion 32 and solidifies when the brush holder 12 is formed, so that the bonding strength between the brush holder 12 and the embedded plate portion 23A is reduced. It is possible to increase the size of the buried plate portion 23A, and to surely prevent the buried plate portion 23A from coming off. In this case, a plurality of holes 31 may be formed by increasing the size of the embedded plate portion 23A in order to increase the bonding strength.

Further, semicircular concave portions 33 are formed on both sides of the base end of the fixing piece 23B. The formation of the concave portion 33 can be achieved by forming the one end face 30 into the cover 3.
This is effective in ensuring the close contact with the back surface of the. Because,
If the fixing piece 23B is simply protruded from the one end face 30, it is difficult to punch out so that no corners of two sides perpendicular to each other are formed, so that the connecting part between the one end face 30 and the fixing piece 23B has two points. Depending on the size of the locking hole 16 of the cover 3 through which the fixing piece 23B is inserted, the one end surface 30 may be closely contacted with the back surface of the cover 3 as shown by a chain line 34 in a circular arc shape. It is not possible. Also,
The concave portion 33 also functions as a drop-out preventing portion together with the holes 31 and the concave portions 32 when the resin enters and solidifies.

In order to fix the brush holder 12 to the lid 3, the brush holder 12 is brought into close contact with the back surface of the lid 3 with the fixing piece 23B of the metal piece 23 and the locking hole 16 of the lid 3 aligned. Then, the fixing piece 23B is inserted into the locking hole 16. When the brush holder 12 is brought into close contact with the lid 3, the embedded plate portion 2 of the metal piece 23 is
One end surface 30 of 3 </ b> A is also in close contact with the back surface of lid 3. Next, when the protruding end portion of the fixing piece 23B that protrudes from the locking hole 16 is bent substantially perpendicularly in the direction of the arrow in FIG. 1 to make close contact with the surface of the lid 3, the brush holder 12 is fixed to the lid 3, Thus, the mounting of the brush holder 12 is completed.

When bending the fixing piece 23B, FIG.
As shown in (a) and (b), the lower surface of the outer peripheral portion of the lid 3 and the lower surface of the brush holder 12 are supported by the receiving jig 36, and the fixing piece 23 </ b> B is bent at a substantially right angle by the pressing tool 37. Press against the surface. At this time, the fixing piece 23 of the metal piece 23 exposed in the hole 27 of the brush holder 12
When a jig 36 is provided with a projection 39 having a groove 38 for holding an end opposite to B, when the fixing piece 23B is pressed and bent by the pressing tool 37, the embedded plate 23A is moved in the direction of arrow A in the direction of arrow A. No rotational force is generated, and the fixing piece 23B can be bent well.

In such a fixing structure of the brush holder 12, it is possible to prevent rattling of the brush holder 12 due to stress relaxation. That is, when the brush holder 12 expands due to an increase in the ambient temperature, the strain increases, and the stress decreases with the passage of time. Therefore, when the temperature returns to normal temperature, the brush holder 12 contracts and the thickness decreases. Even if there is a gap, the lid 3 is sandwiched between the one end face 30 of the metal piece 23 and the fixing piece 23B, so that a gap occurs between the lid 3 and the fixing piece 23B or the one end face 30. Nothing. Therefore, there is no rattling of the brush holder 12 or generation of noise due to this.
A quiet motor can be provided.

In this embodiment, the metal piece 23 is used.
Since it is formed in a flat plate shape, it does not require bending,
It can be manufactured by press working, laser processing, or the like. Particularly in the case of press working, it can be manufactured at a lower cost than the conventional L-shaped metal piece 15 shown in FIG.

In the above embodiment, 3
Although the example in which the brush holder 12 is fixed to the lid 3 by the metal pieces 23 has been described, the present invention is not limited to this, and for example, one metal piece having a plurality of the fixing pieces 23B is used. You may.

[0021]

As described above, the DC motor according to the present invention employs a structure in which the lid is sandwiched by the metal pieces. There is no gap between the pieces. Accordingly, the brush holder does not rattle due to the vibration and does not generate noise, and the reliability of mounting the brush holder can be improved. Further, since the metal piece is formed in a flat plate shape, a bending step is not required, and the metal piece can be manufactured at low cost by press working or the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view taken along the line II of FIG. 2, showing an embodiment of a DC motor according to the present invention.

FIG. 2 is a side view of the motor.

FIGS. 3A and 3B are a front view and a side view of a metal piece.

FIGS. 4A and 4B are cross-sectional views showing holding of a metal plate during molding.

FIGS. 5A and 5B are cross-sectional views showing bending of a fixing piece.

FIG. 6 shows a conventional example of a DC motor.
It is a line sectional view.

FIG. 7 is a side view of the motor.

FIG. 8 is a perspective view of a metal piece.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... DC motor, 2 ... Case, 3 ... Lid, 4 ... Housing, 6 ... Rotating shaft, 7 ... Armature, 8 ... Commutator, 9 ...
Magnet, 10: power supply brush, 12: brush holder,
20: DC motor, 23: metal piece, 23A: buried plate,
23B: fixed piece, 30: one end face of metal piece, 31: hole.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02K 13/00

Claims (2)

(57) [Claims] 1. A brush holder to which a power supply brush is attached.
Cylindrical housing for housing the rotor, rotating shaft, magnet, etc.
And a lid that covers the opening of the case
Then, the projecting end of the metal piece embedded in the brush holder is
In the DC motor fixing the brush holder on the lid by bending is inserted into the locking hole of the lid, one end surface is embedded in the brush holder of the cover and exposed to the surface of the brush holder A buried plate that contacts the back surface,
A DC motor, wherein the metal piece is formed by a fixed piece which is integrally protruded from the one end face of the buried plate portion, inserted into a locking hole of the lid, and bent. 2. The direct-current motor according to claim 1, wherein the metal piece is formed in a flat plate shape, and a buried preventing portion is formed in the buried plate portion to prevent the brush piece from coming off from the brush holder. DC motor characterized by being integrally molded.