JP2003125552A - Dc motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate positioning of a yoke 7 and a brush holder 15, and to improve the assembly performance. SOLUTION: A brush holder 15 comprises a holder main part 15A, made of resin and holder elements 15B made of metal and attached to the holder main part 15A. A grommet 30, made of rubber, is pushed into the outside diameter part of the holder main part 15A and lead wires 33 which are electrically connected with positive pole brushes 13A are drawn out of a yoke 7 via the grommet 30. The grommet 30 has coupling grooves 30b, coupled with U-shaped notches 7a formed in the opening end of the yoke 7 and the coupling grooves 30b, are pushed into the notches 7a from the opening end of the yoke 7 to fix the grommet 30 to the yoke 7. With such a constitution, the brush holder 15 is positioned relatively to the yoke 7 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 of positioning a yoke and a brush holder.

[0002]

2. Description of the Related Art As a conventional technique, Japanese Patent Laid-Open No. 7-19406
There is 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 the bracket.

[0003]

However, the bracket interposed between the torque sensor unit and the motor casing has a hole through which a screw passes.
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, since the circumferential position of the bracket may be displaced by the clearance, it is 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 due to vibration, the relative position with respect to the motor casing is displaced, There is a problem in that the yoke and the brush holder are displaced in the circumferential direction. Further, since the bracket is sandwiched between the torque sensor unit and the motor casing to fix the screws, it is necessary to align the positions of the three holes when fixing the screws. In this case, even if any one of the three parts cannot be assembled if the positions of the holes are displaced, there is a problem that the assembly takes time. The present invention has been made in view of the above circumstances, and an object thereof is to provide a DC motor that can easily position a yoke and a brush holder and can be easily assembled.

[0005]

[Means for Solving the Problems] (Means for Claim 1) A grommet is fixed to a brush holder, and the yoke and the brush holder are positioned through the grommet. In this structure, 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,
It is possible to prevent the positional deviation between the yoke and the brush holder in the circumferential direction.

(Means for Claim 2) The grommet is made of rubber and is fixed to the yoke and the brush holder in a press-fitted state. In this case, since the grommet has elasticity, rattling due to vibration between the yoke and the brush holder can be prevented. Further, since the grommet can reduce a processing error by using a molded product of a mold, it is possible to prevent rattling due to a defective shape of the grommet.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION 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 sectional view of a rear portion of the starter showing an assembled state of the grommet, and FIG. 2 is a sectional view of the starter. As shown in FIG. 2, the starter 1 includes a starter motor 2 (DC motor of the present invention) that receives a power supply to generate a rotational force, a speed reducer (described later) that reduces the rotational speed of the starter motor 2, The output shaft 3 to which the rotational force of the starting motor 2 is transmitted via the device, the pinion gear 4 movably provided on the output shaft 3, the output shaft 3
One-way clutch 5 that transmits the rotation of the pinion gear 4 to the pinion gear 4,
The starter motor 2 includes a magnet switch 6 for opening and closing an internal contact (not shown) interposed in the energizing circuit.

The starting motor 2 includes a yoke 7 formed by molding a mild steel plate into a cylindrical shape, an end frame 8 that closes a rear end opening of the yoke 7, and a fixed magnetic pole 9 (for example, a fixed magnetic pole fixed to 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, brushes 13 (13A, 13B) slidingly contacting the commutator surface 11, and a brush spring 1 for pressing the brush 13 against the commutator surface 11.
4, a brush holder 15 for holding the brush 13, and the like.

The speed reducer includes a sun gear 16 having external teeth formed on the outer circumference of the armature shaft 10, a ring-shaped internal gear 17 having internal teeth formed on the outer circumference of the sun gear 16 in the radial direction, a sun gear 16 and an internal gear 17. And a planetary gear 18 meshing with both gears 16 and 17, and the planetary gear 18 revolves around the outer periphery of the sun gear 16 while revolving around the sun gear 16, so that the planetary gear 18 revolves through a pin 19. Is transmitted to the output shaft 3.

The output shaft 3 is disposed coaxially with the armature shaft 10 in front of the armature 12 and has a front end portion bearing 20.
It is supported by the front housing 21 via the bearing, and the rear end is supported by the bearing portion 23 provided integrally with the internal gear 17 via the bearing 22. The internal gear 17 is fitted on the inner peripheral surface of the yoke 7 and its rotation is restricted. The pinion gear 4 has a bearing 24 on the outer circumference of the output shaft 3.
Is slidably fitted through the output shaft 3 when the engine is started.
It moves upward and meshes with the ring gear 25 of the engine to transmit 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 so as to be movable 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, the 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 according to the movement of a built-in plunger (not shown), and the pinion gear 4 via the lever 26.
Is moved back and forth on the output shaft 3 together with the one-way clutch 5.

Next, the structure around the brush holder 15 according to the present invention will be described. The brush holder 15 includes a resin holder main body 15A and a metal holder member 15B (for example, stainless steel, brass, etc.) provided in the holder main body 15A. As shown in FIG. 1, the holder main body 15A is provided in a substantially annular body having a round hole 15a in the center thereof, and a recess 15b for holding the holder member 15B around the round hole 15a (see FIG. 3 / FIG. 1). A-A sectional view of) is 4
Metal fittings 27 for screwing the end frame 8 are formed at two locations which are formed at a location and which are opposed to each other in the radial direction through the center of the round hole 15a (see FIG. 4 / BB in FIG. 1).
Sectional view). The metal fitting 27 is formed with a screw hole 29 into which the screw 28 is screwed.

A press-fitting recess 15c for press-fitting a later-described grommet 30 is provided on the outer diameter portion of the holder body 15A. The press-fitting recess 15c is provided in a semicircular recess 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 rectangular cross section, and as shown in FIG. 3, the holder member 15B is fitted into the concave portion 15b of the holder body 15A and has a cut-and-raised claw 15d provided on one side surface. The engagement with the inner surface of the recess 15b prevents the recess 15b from falling off. Further, the brush spring 1 is attached to the holder member 15B.
4, a support arm 31 for supporting 4 is integrally provided, and a tip of the support arm 31 is locked in a groove formed in the holder body 15A.

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

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

Next, the assembly process around the brush holder 15 will be described. As shown in FIG. 1, the grommet 30 includes a semi-circular press-fitting portion 30a that is press-fitted into the press-fitting recess 15c of the holder body 15A and a U-shaped cutout portion provided at the opening end of the yoke 7. 7a (see FIG. 1) is provided with a fitting groove 30b. First, after the press-fitting portion 30a of the grommet 30 is press-fitted into the press-fitting recess 15c of the holder body 15A and fixed to the holder body 15A,
The fitting groove 30b of the grommet 30 is press-fitted into the notch 7a from the opening end of the yoke 7 and attached.

Next, the end frame 8 is arranged behind the brush holder 15, and the screw 28 is inserted into the screw hole 29 of the metal fitting 27 attached to the holder body 15A through the through hole 8a formed in the end frame 8. The brush holder 15 is fixed to the end frame 8 by screwing. After that, the yoke 7 and the end frame 8 are fastened together to the front housing 21 by screwing from the rear of the end frame 8 through a through bolt (not shown) into a screw hole (not shown) provided in the front housing 21.

(Effects of this Embodiment) According to the structure of this embodiment, the yoke 7 and the brush holder 1 are interposed via the grommet 30.
5 can be positioned in the circumferential direction. In this case, since the grommets are press-fitted into the yoke 7 and the brush holder 15 (holder main body 15A), respectively, there is no clearance that would occur when the conventional screws are used, so that the rattling of the brush holder 15 can be prevented and the brush holder 15 can be prevented from rattling. The positioning accuracy of can be improved. Further, since it is not necessary to position the screws 7 with screws, the yoke 7 and the brush holder 15 can be positioned easily and reliably. Furthermore, since the grommet 30 is made of rubber, it has excellent vibration resistance and can prevent rattling due to vibration.

Further, the yoke 7 is provided through the end frame 8.
Since it is not necessary to position the brush holder 15 with the brush holder 15,
When fixing the end frame 8 and the brush holder 15 with screws, it is not necessary to position them. Therefore, the through hole 8a formed in the end frame 8 can be a long hole having a diameter larger than the screw diameter. Thereby, the holder member 1
Since 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 aligned with each other, the screwing operation can be easily performed.
In addition, if the through hole 8a of the end frame 8 is an elongated hole,
Since it is not necessary to use a screw with a pilot whose tip is conically pointed, it is possible to prevent cost increase.

In this embodiment, the DC motor of the present invention is applied to the starter motor 2 of the starter 1. However, 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 drawings]

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

FIG. 2 is a sectional view of a starter.

3 is a cross-sectional view taken along the line AA of FIG.

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

[Explanation of symbols]

2 Starting motor (DC motor) 7 York 9 fixed magnetic pole 11 commutator face 12 Armature 13 brushes 15 Brush holder 30 Grommet 33 lead wire

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H605 AA08 BB05 BB09 BB20 CC01                       CC02 CC03 CC06 CC07 DD05                       DD09 EA02 EA11 EA13 EA25                       EC02 EC04 EC08 FF08 GG04                       GG05 GG06                 5H613 AA01 AA02 BB12 BB15 BB23                       BB24 BB29 GA05 GA13 GA14                       GB18 KK04 KK05 PP02 PP03

Claims (5)

[Claims] 1. A yoke (7) having a plurality of fixed magnetic poles fixedly provided on an inner peripheral surface thereof, and a lead wire (33) attached to the yoke and taken out from the inside of the yoke to the outside thereof is inserted through the yoke. A grommet (30) for insulatingly holding the wire from the yoke, an armature (12) rotatably supported on the inner circumference of the fixed magnetic pole, and a face type commutator surface substantially orthogonal to the shaft provided on the armature. A DC electric motor comprising a brush (13) in sliding contact with a brush holder (15) for holding the brush, wherein the grommet is fixed to the brush holder, and the yoke and the brush holder are surrounded by the grommet. A DC motor characterized in that it is directionally positioned. 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-fitted state. 3. The grommet is provided with a fitting groove (30b) that fits into a U-shaped notch (7a) provided at the opening end of the yoke. Item 3. The DC motor according to Item 1 or 2. 4. The brush comprises two positive electrode brushes (13).
A) and two negative electrode brushes (13B), each housed in a brush holder (15B), and each of the two positive electrode brushes (13A) is a pigtail (13a) taken out from the holder (15B). 4. The DC motor according to claim 1, wherein an end portion of (1) is connected to the lead wire. 5. An end frame (8) is arranged behind the brush holder (15) and the end frame (8) is arranged.
The screw (28) is screwed into the screw hole (29) of the metal fitting (27) attached to the brush holder (15A) through the through hole (8a) formed in the end frame (8). 5. The DC motor according to claim 1, wherein the brush holder (15) is fixed.