JP2001136713A - Dc motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate positioning of a yoke 7 and a brush holder 15, and improve assembling ability. SOLUTION: A brush holder 15 consists of a holder body 15A and a metallic holder member 15B, included in the holder body 15A. A rubber grommet 30 is pressed into the outer-diameter portion of the holder body 15A, and a lead wire 33 conducted to a positive pole brush 13A through a fitting 32 is taken out to the outside of the yoke via the grommet 30. The grommet 30 has a fitting groove 30b, fitted into a U-shaped notch 7a formed on the opening end off the yoke 7 and is mounted, by pressing the fitting groove 30b into the notch 7a from the opening end of the yoke 7. The yoke 7 and the brush holder 15 can be positioned via the grommet 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC motor, and more particularly to a method for positioning a yoke and a brush holder.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open No. 7-19406 discloses a conventional technique.
No. 6 publication. In the motor disclosed in this publication, a holder stay having a brush holder is screwed to a bracket, and a torque sensor unit is screwed to a flange portion of a motor casing forming a yoke via a bracket.

[0003]

However, the bracket interposed between the torque sensor unit and the motor casing is provided with a hole for passing a screw.
The inner diameter of this hole is formed larger than the screw diameter. In this case, when the bracket is sandwiched between the torque sensor unit and the motor casing and screwed, a clearance is generated between the outer diameter of the screw and the inner diameter of the hole formed in the bracket. As a result, the circumferential position of the bracket may be displaced by the amount of the clearance, so that it has been difficult to position the yoke and the brush holder in the circumferential direction.

Further, even if the assembly is completed with the motor casing and the brush holder positioned, if the bracket moves in the circumferential direction by the clearance by vibration, the relative position with respect to the motor casing is displaced. There has been a problem that the circumferential positions of the yoke and the brush holder are shifted. Further, since the bracket is interposed between the torque sensor unit and the motor casing with screws, it is necessary to align the positions of the three holes when screwing. In this case, if any one of the three components is displaced in the position of the hole, it becomes impossible to assemble, so that there is a problem that the assembling takes time. SUMMARY OF THE INVENTION The present invention has been made based on the above circumstances, and an object of the present invention is to provide a DC motor capable of easily positioning a yoke and a brush holder and improving assemblability.

[0005]

The grommet is fixed to the brush holder, and the yoke and the brush holder are positioned via the grommet. In this configuration, the grommet is attached to the yoke, and the grommet is fixed to the brush holder, so that the yoke and the brush holder can be positioned via the grommet,
The displacement of the yoke and the brush holder in the circumferential direction can be prevented.

The grommet is made of rubber, and is fixed to the yoke and the brush holder in a press-fit state. In this case, since the grommet has elasticity, it is possible to prevent rattling between the yoke and the brush holder due to vibration. In addition, the use of a grommet formed by a mold can reduce a processing error, thereby preventing rattling due to a defective shape of the grommet.

[0007]

Next, an embodiment in which the DC motor of the present invention is applied to a starter will be described. FIG. 1 is a radial cross-sectional view of the rear part of the starter showing the assembled state of the grommet, and FIG. 2 is a cross-sectional view of the starter. As shown in FIG. 2, the starter 1 includes a starting motor 2 (a DC motor of the present invention) that generates a rotational force when energized, a speed reducing device (described later) that reduces the rotational speed of the starting motor 2, An output shaft 3 to which the torque of the starting motor 2 is transmitted via a device, a pinion gear 4 movably provided on the output shaft 3, an output shaft 3
One-way clutch 5 for transmitting the rotation of the
It is composed of a magnet switch 6 for opening and closing an internal contact (not shown) interposed in an energizing circuit of the starting motor 2.

The starting motor 2 includes a yoke 7 formed of a soft steel plate in a cylindrical shape, an end frame 8 for closing a rear end opening of the yoke 7, and a fixed magnetic pole 9 (for example, fixed on the inner peripheral surface of the cylinder of the yoke 7). A permanent magnet), an armature 12 having a face-type commutator surface 11 substantially orthogonal to the shaft 10, a brush 13 (13A, 13B) slidingly contacting the commutator surface 11, and a brush spring 1 pressing the brush 13 against the commutator surface 11.
4. A brush holder 15 for holding the brush 13 and the like.

The reduction gear transmission includes a sun gear 16 having external teeth formed on the outer periphery of the armature shaft 10, a ring-shaped internal gear 17 having internal teeth formed on a radially outer periphery of the sun gear 16, and a sun gear 16 and the internal gear 17. And a planetary gear 18 meshing with both gears 16 and 17. The planetary gear 18 revolves while rotating around the outer periphery of the sun gear 16, so that the planetary gear 18 revolves via a pin 19. And transmitted to the output shaft 3.

The output shaft 3 is arranged coaxially with the armature shaft 10 in front of the armature 12 and has a front end bearing 20.
And a rear end portion is supported by a bearing portion 23 provided integrally with the internal gear 17 via a bearing 22. The rotation of the internal gear 17 is restricted by being fitted to the inner peripheral surface of the yoke 7. The pinion gear 4 has a bearing 24 on the outer periphery of the output shaft 3.
Slidably fit through the output shaft 3 when the engine is started.
It moves upward and meshes with the ring gear 25 of the engine, and transmits the rotation of the output shaft 3 to the ring gear 25.

The one-way clutch 5 is helically spline-fitted to the outer periphery of the output shaft 3 and is provided so as to be able to move back and forth on the output shaft 3 integrally with the pinion gear 4, and transmits the rotation of the output shaft 3 to the pinion gear 4. At the same time, when the rotation speed of the pinion gear 4 exceeds the rotation speed of the output shaft 3 due to the start of the engine, power transmission between the output shaft 3 and the pinion gear 4 is cut off. The magnet switch 6 opens and closes the internal contact with the movement of a built-in plunger (not shown), and a pinion gear 4 via a lever 26.
Is moved back and forth on the output shaft 3 together with the one-way clutch 5.

Next, the configuration around the brush holder 15 according to the present invention will be described. The brush holder 15 includes a resin holder body 15A and a metal (for example, stainless steel, brass, etc.) holder member 15B provided in the holder body 15A. As shown in FIG. 1, the holder body 15A is provided in a substantially annular body having a round hole 15a in the center, and a concave portion 15b for holding the holder member 15B around the round hole 15a (see FIG. 3 / FIG. 1). AA cross section of FIG.
Metal fittings 27 for screwing the end frame 8 are attached to two locations formed and opposed in the radial direction through the center of the round hole 15a (see FIG. 4 / BB in FIG. 1).
Sectional view). A screw hole 29 for screwing a screw 28 is formed in the metal fitting 27.

A press-fit recess 15c for press-fitting a grommet 30, which will be described later, is provided in the outer diameter portion of the holder body 15A. The press-fit recess 15c is provided in a semicircular shape on both opposing wall surfaces facing each other at a predetermined interval in the circumferential direction (see FIG. 1). The holder member 15B is formed by bending a metal plate into a tubular shape having a square cross section, and is inserted into a concave portion 15b of the holder body 15A as shown in FIG. 3 to form a cut-and-raised claw 15d provided on one side surface. The engagement with the inner surface of the concave portion 15b prevents the concave portion 15b from falling off. Further, the brush spring 1 is attached to the holder member 15B.
A support arm 31 for supporting the support arm 4 is provided integrally, and a tip of the support arm 31 is locked in a groove formed in the holder main body 15A.

As shown in FIG. 1, the brush 13 comprises two positive electrode brushes 13A and two negative electrode brushes 13B, each of which is accommodated in a holder member 15B. The two positive brushes 13A are respectively provided with the holder member 1
The end of the pigtail 13a taken out of 5B is connected to a common metal fitting 32 by welding or the like, and is electrically connected to an internal contact (fixed contact) of the magnet switch 6 via a lead wire 33 connected to the metal fitting 32. Have been. The lead wire 33 is inserted through a rubber grommet 30 that is press-fitted into the outer diameter portion of the holder main body 15A, and is taken out of the yoke 7 via the grommet 30.

Each of the two negative brushes 13B has a metal fitting 27a in which an end of a pigtail 13b taken out of the holder member 15B is attached to the holder body 15A.
And grounded via the metal fitting 27a. Therefore, one metal fitting 27a attached to the holder main body 15A also serves as the ground terminal of the negative electrode brush 13B. However, the other fitting 27b has the same shape as the one fitting 27a, but does not mean that the pigtail 13a of the positive brush 13A is connected. The brush spring 14 is formed by spirally winding a thin and thin plate-like spring material, and its tip portion contacts the rear end surface of the brush 13 to urge the brush 13 toward the commutator surface 11.

Next, an assembling process around the brush holder 15 will be described. As shown in FIG. 1, the grommet 30 has a semicircular press-fit portion 30a press-fit into the press-fit recess 15c of the holder body 15A, and a U-shaped notch provided at the open end of the yoke 7. 7a (see FIG. 1) is provided with a fitting groove 30b. First, after the press-fit portion 30a of the grommet 30 is press-fitted into the press-fit recess 15c of the holder body 15A and fixed to the holder body 15A,
The fitting groove 30b of the grommet 30 is pressed into the notch 7a from the opening end of the yoke 7 by press-fitting.

Subsequently, the end frame 8 is disposed behind the brush holder 15, and a screw 28 is inserted into a screw hole 29 of a metal fitting 27 attached to the holder body 15A through a through hole 8a formed in the end frame 8. Screw-in and fix the brush holder 15 to the end frame 8. Thereafter, a screw is inserted into a screw hole (not shown) provided in the front housing 21 through a through bolt (not shown) from behind the end frame 8, and the yoke 7 and the end frame 8 are fastened to the front housing 21 together.

(Effects of the present embodiment) According to the configuration of the present embodiment, the yoke 7 and the brush holder 1 are provided via the grommet 30.
5 can be positioned in the circumferential direction. In this case, the grommet is pressed into the yoke 7 and the brush holder 15 (holder body 15A), so that there is no clearance that would occur in the case of screwing in the related art. Positioning accuracy can be improved. Further, since there is no need to perform positioning by screwing, the positioning between the yoke 7 and the brush holder 15 can be performed easily and reliably. Further, since the grommet 30 is made of rubber, the grommet 30 is excellent in vibration resistance and can prevent rattling due to vibration.

Further, the yoke 7 is provided via the end frame 8.
And the brush holder 15 need not be positioned,
When the end frame 8 and the brush holder 15 are screwed together, there is no need to position them. For this reason, the through hole 8a formed in the end frame 8 can be made into a long hole larger than the screw diameter. Thereby, the holder member 1
Since the positions of the screw hole 29 of the metal fitting 27 attached to the 5B and the through hole 8a of the end frame 8 can be easily adjusted, screwing work can be easily performed.
When the through hole 8a of the end frame 8 is made to be a long hole,
Since there is no need to use a screw with a pilot whose tip is conical, the cost can be prevented from increasing.

In the present embodiment, the DC motor of the present invention is applied to the starter motor 2 of the starter 1, but it goes without saying that the same effect can be obtained even when the DC motor of the present invention is used alone.

[Brief description of the drawings]

FIG. 1 is a radial cross-sectional view of a rear portion of a starter showing an assembled state of a grommet.

FIG. 2 is a sectional view of a starter.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a sectional view taken along line BB of FIG. 1;

[Explanation of symbols]

 2 Starting motor (DC motor) 7 Yoke 9 Fixed magnetic pole 11 Commutator surface 12 Armature 13 Brush 15 Brush holder 30 Grommet 33 Lead wire

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H604 BB01 BB07 BB14 CC02 CC05 DB01 PC05 QA01 QB16 5H613 AA02 AA03 BB04 BB07 BB15 BB28 BB32 BB35 GA12 GA13 GB01 GB02 GB08 GB09 GB12 GB14 GB17 GB18 KK05 PP03

Claims (2)

[Claims] 1. A yoke having a plurality of fixed magnetic poles fixedly mounted on an inner peripheral surface thereof, and a lead wire attached to the yoke and taken out from inside to outside of the yoke is inserted therethrough, and the lead wire is insulated from the yoke. A DC motor comprising: a grommet for holding; an armature rotatably supported on the inner periphery of the fixed magnetic pole; a brush slidably contacting a commutator surface provided on the armature; and a brush holder for holding the brush. A DC motor, wherein the grommet is fixed to the brush holder, and the yoke and the brush holder are positioned via the grommet. 2. The DC motor according to claim 1, wherein the grommet is made of rubber and is fixed to the yoke and the brush holder in a press-fit state.