(19)
(11)EP 2 267 872 A1

(12)EUROPEAN PATENT APPLICATION
published in accordance with Art. 153(4) EPC

(43)Date of publication:
29.12.2010 Bulletin 2010/52

(21)Application number: 09725871.9

(22)Date of filing:  19.03.2009
(51)Int. Cl.: 
H02K 13/00  (2006.01)
H02K 23/66  (2006.01)
H02K 23/04  (2006.01)
(86)International application number:
PCT/JP2009/055493
(87)International publication number:
WO 2009/119456 (01.10.2009 Gazette  2009/40)
(84)Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO SE SI SK TR
Designated Extension States:
AL BA RS

(30)Priority: 24.03.2008 JP 2008075902
30.10.2008 JP 2008280551

(71)Applicant: Mitsuba Corporation
Kiryu-shi Gunma 376-8555 (JP)

(72)Inventors:
  • ISHIKAWA, Masaru
    Kiryu-shi Gunma 376-8555 (JP)
  • SAKATA, Kenji
    Kiryu-shi Gunma 376-8555 (JP)

(74)Representative: Plaçais, Jean Yves 
Cabinet Netter, 36, avenue Hoche
75008 Paris
75008 Paris (FR)

  


(54)MOTOR


(57) A motor 10 includes: a yoke on whose inner surface a four-pole magnet is attached; a gear case 15 jointed to an opening portion of the yoke and storing a speed-reduction mechanism; a brush holder 30 stored in an opening portion 15a of the gear case and having a through hole 31 penetrated by a commutator 23 attached to an armature shaft 21 in a center of the brush holder; and a first brush 36, a second brush 35, and a third brush 37 which are stored so as to freely come in and out to/from three brush storing portions 32, 33, and 34 formed so as to interpose the through hole 31 in the brush holder 30. In the motor, the second brush 35 is arranged at a position shifted from the first brush 36 in a rotational direction by 90 degrees, and a third brush 37 is arranged within an included angle opposite to an included angle formed by the first brush 36 and the second brush 35.




Description

TECHNICAL FIELD



[0001] The present invention relates to a motor such as a wiper motor used in a wiper device of wiping a wiped surface such as a windshield glass in an auto vehicle.

BACKGROUND ART



[0002] As a wiper motor of this type, there is a motor known such that, by providing the number of motor poles (field portions) as four or more poles for the multipolarity, magnetic saturation in a yoke is reduced and torque is improved with improvement of an operating point, and the motor can be sized down (see, for example, Patent Document 1).

Patent Document 1: Japanese Patent Application Laid-Open Publication No. 2007-143278 (FIGs. 2 and 3)


DISCLOSURE OF THE INVENTION


PROBLEMS TO BE SOLVED BY THE INVENTION



[0003] For example, when a four-pole motor is applied as the wiper motor, there are provided at least a pair of brushes which are arranged away from each other by 90 degrees around a rotational direction. Also, when a driving speed of the wiper can be switched, another brush shifted from the pair of brushes by a predetermined angle in the rotational direction is required. Therefore, in a conventional four-pole motor, the brush is arranged in a circular-shaped brush holder as described in Patent Document 1.

[0004] However, when the brush holder has the circular shape, an opening portion of a gear case and/or an opening portion of a yoke in which the brush holder is equipped are required to also have the circular shape, and therefore, a whole motor cannot be sized down and thinned.

[0005] Accordingly, the present invention is made for solving the above-described problems, and a preferred aim of the present invention is to provide a motor which can be sized down and thinly lightweight as a whole by forming the shape of the brush holder as small as possible.

MEANS FOR SOLVING THE PROBLEMS



[0006] A motor of the present invention includes: a motor yoke of rotatably supporting an armature shaft; a four-pole magnet fixed on an inner surface of the motor yoke; an armature core having a plurality of slots each arranged in a rotational direction and fixed at the armature shaft; a commutator having a plurality of commutator bars each arranged in the rotational direction and fixed at the armature shaft; winding wound around the slots of the armature core and electrically connected with each of the commutator bars; a connection member electrically connected with the commutator bars whose potentials are to be the same with each other; a first brush slidingly contacted with the commutator bar; a second brush shifted from the first brush by 90 degrees and supplying a driving current to the winding; and a brush holder of storing the first brush and the second brush. The brush holder includes: a pair of flat portions opposite to each other; and a pair of joint portions of jointing between the pair of flat portions, and the first brush and the second brush are arranged on one side of the pair of joint portions.

[0007] In the motor of the present invention, a third brush is arranged on the other side of the pair of joint portions.

[0008] In the motor of the present invention, a third brush is arranged on one side of the pair of joint portions.

[0009] In the motor of the present invention, the second brush is a low-speed driving brush, and the third brush is a high-speed driving brush.

[0010] A motor of the present invention includes: a motor yoke of rotatably supporting an armature shaft; a four-pole magnet fixed on an inner surface of the motor yoke; an armature core having a plurality of slots each arranged in a rotational direction and fixed at the armature shaft; a commutator having a plurality of commutator bars each arranged in the rotational direction and fixed at the armature shaft; winding wound around the slots of the armature core and electrically connected with each of the commutator bars; a first brush slidingly contacted with the commutator bar; a second brush shifted from the first brush by 90 degrees and supplying a driving current to the winding; and a brush holder of storing the first brush and the second brush. The brush holder includes: a pair of flat portions opposite to each other; and a pair of joint portions of jointing between the pair of flat portions, and the first brush and the second brush are arranged on one side of the pair of joint portions.

[0011] In the motor of the present invention, on the other side of the pair of joint portions, a first opposite brush arranged away from the first brush by 180 degrees is arranged, and a second opposite brush arranged away from the second brush by 180 degrees and away form the first opposite brush by 90 degrees is arranged.

[0012] In the motor of the present invention, the first brush and the second brush are arranged on one side of the pair of joint portions, the third brush is arranged on the other side of the pair of joint portions, and a third opposite brush is arranged away from the third brush by 180 degrees.

[0013] In the motor of the present invention, a connection member is electrically connected with the commutator bars whose potentials are to be the same with each other.

EFFECTS OF THE INVENTION



[0014] According to the present invention, in the four-pole motor, the first brush and the second brush are shifted from each other by 90 degrees on one side of the pair of joint portions in the brush holder, so that the brush holder can be formed in an oval shape and can be sized down, and therefore, a whole motor can be sized down and thinly lightweight by the down sizing.

[0015] According to the present invention, the third brush is arranged on one side or the other side of the pair of joint portions in the brush holder, and therefore, the third brush can be arranged in the brush holder which is formed in the oval shape and is sized down. Also, the second brush is the low-speed driving brush, and the third brush is the high-speed driving brush, so that the whole motor whose rotational speed can be switched into the low-speed driving and the high-speed driving can be sized down and thinly lightweight.

BRIEF DESCRIPTIONS OF THE DRAWINGS



[0016] 

FIG. 1 is a side view illustrating a wiper motor according to a first embodiment of the present invention;

FIG. 2 is a plan view of the wiper motor;

FIG. 3A is a cross-sectional view of the wiper motor;

FIG. 3B is a winding diagram in an armature stored in the wiper motor;

FIG. 4 is a front view of a gear case in the wiper motor;

FIG. 5 is a cross-sectional view of a principal part of a yoke jointed to the gear case;

FIG. 6 is an explanation diagram describing a relation among magnetic poles, brush holders, and brushes stored in an opening portion of the gear case;

FIG. 7 is a front view of a gear case in a wiper motor according to a second embodiment of the present invention;

FIG. 8 is a front view of a gear case in a wiper motor according to a third embodiment of the present invention; and

FIG. 9 is a front view of a gear case in a wiper motor according to a fourth embodiment of the present invention.


BEST MODE FOR CARRYING OUT THE INVENTION



[0017] Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings.

[0018] As illustrated in FIGs. 1 to 5, a wiper motor (motor) 10 includes: a bottomed substantial-cylindrical yoke (motor yoke) 11 storing an armature 20; a gear case 15 in which a flange portion 11b in a periphery of an opening portion 11a in the yoke 11 is fastened to be fixed through a screw 19A with a flange portion 15b in an opening portion 15a functioning as a brush-holder storing portion, and in which a speed-reduction mechanism (speed-reduction mechanism unit) 26 of reducing a rotational speed of an armature shaft 21 of the armature 20 is stored; and a gear-case cover 18 fastened to be fixed through a screw 19B so as to cover an opening portion 15d of a speed-reduction-mechanism storing portion 15c in the gear case 15.

[0019] As illustrated in FIGs. 3A and 5, on an inner peripheral surface 11c of the yoke 11, an N-pole magnetized magnet 12n and an S-pole magnetized magnet 12s are alternately adhered by adhesives or others so that they are totally 4 magnets, and a cylindrically-formed magnet storing portion 11d is provided. And, as illustrated in FIG. 3A, the armature shaft 21 is rotatably supported by a shaft bearing 13 fitted on a bottomed cylindrical portion 11e of the yoke 11, a shaft bearing 16 fitted on a cylindrical portion 15e of the gear case 15, and others. As illustrated in FIGs. 2 and 3A, on a tip side of the armature shaft 21, a pair of worms 22 and 22' whose torsional directions are opposite to each other are formed.

[0020] At a position opposite to the four-pole magnets 12n and 12s in the armature shaft 21, the armature 20 is attached. The armature 20 is fixed on a base-end portion side of the armature shaft 21, and is configured with: an armature core 20a having 18 coil-wound portions (slots) each arranged in the rotational direction; and an armature coil (winding) 20b wound around the coil-wound portions of the armature core 20a. As illustrated in FIG. 3B, the armature coil 20b is repeatedly wound from one coil-wound portion of the armature core 20a to a different coil-wound portion thereof with a predetermined interval as shifting toward the rotational direction of the armature shaft 21 by lap winding of a predetermined times, so that the coil is wound around each coil-wound portion, and is electrically connected with each commutator bar 23a described later.

[0021] Also, as illustrated in FIGs. 3A and 4, at a position opposite to the opening portion 11a of the yoke 11 in the armature shaft 21 and the opening portion 15a of the gear case 15, a commutator 23 is fixed. As illustrated in FIG. 3B, the commutator 23 includes the same number of commutator bars 23a as that of the coil-wound portions of the armature core 20a, and each of the commutator bars 23a arranged in the rotational direction is electrically connected with the armature coil 20b. Further, commutator bars 23a whose potentials are the same with each other of the plurality of commutator bars 23a are electrically connected with each other by an equalizer connection 23b functioning as a connection member.

[0022] As illustrated in FIGs. 1 to 5, in substantially center of a ceiling-wall portion of the gear case 15, an upper portion 17a of an output shaft 17 is protruded outside. To a lower portion 17b of the output shaft 17, an output gear 24 is jointed. The output gear 24 is meshed with each small-diameter gear 25a of a pair of worm wheels 25 and 25. Also, each large-diameter gear 25b of the pair of worm wheels 25 and 25 is meshed with a pair of worms 22 and 22' in the armature shaft 21. These pair of worms 22 and 22', the output gear 24, and the pair of worm wheels 25 and 25 are stored inside the speed-reduction-mechanism storing portion 15c of the gear case 15, and configure the speed-reduction mechanism 26. Note that the upper portion 17a of the output shaft 17 is jointed to a wiper shaft of a wiper arm through a linkage mechanism (their illustrations are omitted), and when a wiper motor 10 is operated, the wiper arm is swung in an area of predetermined angles to wipe a windshield glass.

[0023] As illustrated in FIGs. 3A and 4, at a position opposite to the commutator 23 inside the opening portion 15a of the gear case 15, three brushes 35, 36, and 37 are attached through the brush holder 30 so as to contact with the commutator bars 23a of the commutator 23. As illustrated in FIGs. 4 and 5, the opening portion 11a of the yoke 11 is shaped in an oval shape which is formed of: a pair of flat portions 11f and 11f opposite to each other; and a pair of arc portions 11g and 11g jointing between the pair of flat portions 11f and 11f. In the yoke 11, an opening joint portion 11h and a bottomed cylindrical portion 11e are monolithically formed so as to continuously connect between the opening portion 11a having the oval shape and a magnet storing portion 11d having a cylindrical shape. The opening portion 15a of the gear case 15 on the other side is shaped in an oval shape which is formed of: a pair of horizontally-long flange-side flat portions 15f and 15f; and a pair of arc portions 15g and 15g. By providing the opening joint portion 11h between the opening portion 11a and the magnet storing portion 11d of the yoke 11, the opening portion 11a of the yoke 11 and the opening portion 15a of the gear case 15 whose shape is larger than that of the magnet storing portion 11d can be jointed to each other as the cylindrical magnet storing portion 11d on which the four-pole magnet is arranged has a small diameter. In this manner, in addition to achieving a down-sized and lighten yoke, the motor can be also sized down and lightened.

[0024] Also, as illustrated in FIGs. 1 and 2, on a pair of opening-portion-side flat portions 15i and 15i continuously formed from the pair of flange-side flat portions 15f and 15f, there are formed triangular-shaped ribs 15h each extending parallely from the flange portion 15b of the opening portion 15a to a shaft center of the armature shaft 21. The rib 15h has a shape that a height of the rib 15h is smaller as the rib 15h is farther away from the flange portion 15b on the pair of opening-portion-side flat portions 15i and 15i side. In this manner, in addition to improving strength of the gear case 15, operating noises and vibrations can be improved by a state that resonance frequencies are difficult to be matched with each other. In the present invention, total 6 ribs 15h are formed such that three ribs are formed on each of the pair of opening-portion-side flat portions 15i and 15i. However, the number or lengths of the ribs 15h can be changed depending on setting of the motor. Also, by setting the rib 15h so as not to be over a height of the flange portion 15b, layout performance is improved.

[0025] Inside the opening portion 15a of the horizontally-long oval-shaped gear case 15, an oval-shaped brush holder 30 is stored, the oval-shaped brush holder 30 being configured with: a pair of flat portions 30a and 30a; and a pair of arc portions (joint portions) 30b and 30b jointing between the pair of flat portions 30a and 30a, and the brush holder 30 is fastened to be fixed at the gear case 15 through screws 39. In a center of the oval-shaped brush holder 30, a circular-shaped through hole 31 in which the commutator 23 in the armature shaft 21 penetrates is formed. And, three brush boxes (brush storing portions) 32, 33, and 34 storing three brushes 35, 36, and 37 so as to freely come in and out are attached so as to interpose the through hole 31 in the brush holder 30.

[0026] As illustrated in FIGs. 4 and 6, each of the first brush box 32 and the second brush box 33 is arranged at both corners on one side of four corners of the oval-shaped brush holder 30, that is on one side of the pair of arc portions 30b and 30b, and the third brush box 34 is arranged between both corners on the other side of the four corners of the oval-shaped brush holder 30, that is on the other side of the pair of arc portions 30b and 30b. That is, the first brush box 32 is arranged at a right-angle position to the second brush box 33 (a position shifted by 90 degrees around the armature shaft 21 in the rotational direction), and the third brush box 34 is arranged within an included angle θ' (θ1 = 90°) opposite to an included angle θ (θ = 90°) formed by these first brush box 32 and second brush box 33.

[0027] And, as illustrated in FIGs. 4 and 6, the low-speed driving brush (second brush) 35 whose polar characteristic is positive (positive pole) is provided inside the first brush box 32, a common brush (first brush) 36 whose polar characteristic is negative (negative pole) is provided inside the second brush box 33, and the high-speed driving brush (third brush) 37 whose polar characteristic is positive (positive pole) is provided inside the third brush box 34, which are provided so as to freely slide. Each of these brushes 35, 36, and 37 is electrically connected with a non-illustrated motor control circuit, and can be switched into two-stage operation speed of the low-speed driving and the high-speed driving.

[0028] According to the wiper motor 10 of the embodiment as described above, in the four-pole motor, the commutator bars 23a whose potentials are to be the same with each other are electrically connected with each other by the equalizer connection 23b, and the common brush 36 and the low-speed driving brush 35 are arranged at the positions where they are shifted from each other by 90 degrees on one side of the pair of arc portions 30b and 30b in the brush holder 30, so that the brush holder 30 in which the brushes 35 and 36 are arranged so as to freely come in and out can be formed in the oval shape and can be sized down, and therefore, the whole wiper motor 10 can be sized down and thinly lightweight by the down sizing. That is, as illustrated in FIGs. 4 and 6, the brush holder 30 is formed in the oval shape, and each of the common brush 36 and the low-speed driving brush 35 is arranged at both corners on one side of four corners of the oval-shaped brush holder 30, so that the opening portion 15a functioning as the brush-holder storing portion of the gear case 15 storing the brush holder 30 can be formed in the horizontally-long oval shape and can be sized down as small as possible, and therefore, the whole wiper motor 10 can be further sized down and thinly lightweight by the down sizing.

[0029] Also, the high-speed-driving brush 37 is arranged within the included angle of 90 degrees opposite to the included angle of 90 degrees formed by the common brush 36 and the low-speed-driving brush 35, that is on the other side of the pair of arc portions 30b and 30b in the oval-shaped brush holder 30, so that the high-speed-driving brush 37 can be arranged in the brush holder 30 which is sized down by the oval shape, and therefore, the whole wiper motor 10 whose rotational speed can be switched into the low-speed driving and the high-speed driving can be sized down and thinly lightweight. Note that, in the present embodiment, the high-speed-driving brush 37 is arranged on the other side of the pair of arc portions 30b and 30b of the oval-shaped brush holder 30. However, this arrangement is not limited to this, and the high-speed-driving brush 37 may be arranged on one side of the pair of arc portions 30b and 30b of the oval-shaped brush holder 30, that is within the included angle of 90 degrees formed by the common brush 36 and the low-speed-driving brush 35.

[0030] Further, even if multipolarity is achieved in the wiper motor 10 which is sized down and thinly lightweight and uses the common brush 36, the low-speed-driving brush 35, and the high-speed-driving brush 37, the rotational speed can be certainly switched into the low-speed driving and the high-speed driving.

[0031] FIG. 7 is a front view of a gear case in a wiper motor according to a second embodiment. Note that the same components as those of the above-described first embodiment are described with the same symbols.

[0032] In the second embodiment, there is provided an armature 20 in which commutator bars 23a whose potentials are the same with each other (which are opposite to each other) of the plurality of commutator bars 23a are electrically connected with each other by the equalizer connection 23b, the brush holder 30 is formed in the oval shape, and each of the first brush 36 and the second brush 35 is arranged at both corners on one side of four corners of the oval-shaped brush holder 30, so that the opening portion 15a functioning as the brush-holder storing portion of the gear case 15 storing the brush holder 30 is formed in the horizontally-long oval shape and can be sized down as small as possible, and therefore, the whole wiper motor 10 can be further sized down and thinly lightweight by the down sizing. Note that, in the second embodiment, there is no brush functioning as the high-speed-driving brush. However, by providing a control circuit for controlling the driving speed of the wiper motor 10 or a control circuit for switching the rotational direction of the armature 20, a wiper device with the control circuit which can be sized down and thinly lightweight can be provided.

[0033] FIG. 8 is a front view of a gear case in a wiper motor according to a third embodiment. Note that the same components as those of the above-described first embodiment are described with the same symbols.

[0034] In the third embodiment, the brush holder 30 is formed in the oval shape, each of the first brush 36 and the second brush 35 is arranged at both corners on one side of four corners of the oval-shaped brush holder 30, and a fourth brush (first opposite brush) 36' opposite to the first brush 36 by 180 degrees is stored in a fourth brush box 33' and a fifth brush (second opposite brush) 35' opposite to the second brush 35 by 180 degrees is stored in a fifth brush box 32','the fourth brush and the fifth brush being arranged at both corners on the other side of the brush holder 30, so that the opening portion 15a functioning as the brush-holder storing portion in the gear case 15 storing the brush holder 30 is formed in the horizontally-long oval shape and can be sized down as small as possible, and therefore, the whole wiper motor 10 can be further sized down and thinly lightweight by the down sizing.

[0035] FIG. 9 is a front view of a gear case in a wiper motor according to a fourth embodiment. Note that the same components as those of the above-described first embodiment are described with the same symbols.

[0036] In the fourth embodiment, the brush holder 30 is formed in the oval shape, each of the first brush 36 and the second brush 35 is arranged at both corners on one side of four corners of the oval-shaped brush holder 30, and the third brush 37 is arranged between both corners on the other side of the four corners of the oval-shaped brush holder 30. Further, the fourth brush (first opposite brush) 36' opposite to the first brush 36 by 180 degrees is stored in the fourth brush box 33' , and the fifth brush (second opposite brush) 35' opposite to the second brush 35 by 180 degrees is stored in the fifth brush box 32', the fourth brush and the fifth brush being arranged at both corners on the other side of the brush holder 30, and a sixth brush (third opposite brush) 37' opposite to the third brush 37 by 180 degrees is stored in a sixth brush box 34', the sixth brush being arranged between both corners on one side of the brush holder 30, so that the opening portion 15a functioning as the brush-holder storing portion of the gear case 15 storing the brush holder 30 is formed in the horizontally-long oval shape and can be sized down as small as possible, and therefore, the whole wiper motor 10 can be further sized down and thinly lightweight by the down sizing.

[0037] Note that, according to the above-described embodiment, the brush holder is stored in the opening portion functioning as the brush-holder storing portion of the gear case. However, the brush holder may be stored in the opening portion of the yoke, or the brush holder may be stored across both of the opening portion of the gear case and the opening portion of the yoke.

INDUSTRIAL APPLICABILITY



[0038] The present invention can be applied in manufacturing a motor which is sized down and thinly lightweight.


Claims

1. A motor comprising:

a motor yoke of rotatably supporting an armature shaft;

a four-pole magnet fixed on an inner surface of the motor yoke;

an armature core having a plurality of slots each arranged in a rotational direction and fixed at the armature shaft;

a commutator having a plurality of commutator bars each arranged in a rotational direction and fixed at the armature shaft;

winding wound around the slots of the armature core and electrically connected with each of the commutator bars;

a connection member electrically connected with the commutator bars whose potentials are to be the same with each other;

a first brush slidingly contacted with the commutator bar;

a second brush shifted from the first brush by 90 degrees and supplying a driving current to the winding; and

a brush holder of storing the first brush and the second brush, wherein

the brush holder includes: a pair of flat portions opposite to each other; and a pair of joint portions of jointing between the pair of flat portions, and

the first brush and the second brush are arranged on one side of the pair of joint portions.


 
2. The motor according to claim 1, wherein
a third brush is arranged on the other side of the pair of joint portions.
 
3. The motor according to claim 1, wherein
a third brush is arranged on one side of the pair of joint portions.
 
4. The motor according to claim 2 or 3, wherein
the second brush is a low-speed driving brush, and the third brush is a high-speed driving brush.
 
5. A motor comprising:

a motor yoke of rotatably supporting an armature shaft;

a four-pole magnet fixed on an inner surface of the motor yoke;

an armature core having a plurality of slots each arranged in a rotational direction and fixed at the armature shaft;

a commutator having a plurality of commutator bars each arranged in the rotational direction and fixed at the armature shaft;

winding wound around the slots of the armature core and electrically connected with each of the commutator bars;

a first brush slidingly contacted with the commutator bar;

a second brush shifted from the first brush by 90 degrees and supplying a driving current to the winding; and

a brush holder of storing the first brush and the second brush, wherein

the brush holder includes: a pair of flat portions opposite to each other; and a pair of joint portions of jointing between the pair of flat portions, and

the first brush and the second brush are arranged on one side of the pair of joint portions.


 
6. The motor according to claim 5, wherein,
on the other side of the pair of joint portions, a first opposite brush arranged away from the first brush by 180 degrees is arranged, and a second opposite brush arranged away from the second brush by 180 degrees and away form the first opposite brush by 90 degrees is arranged.
 
7. The motor according to claim 6, wherein
the first brush and the second brush are arranged on one of the pair of joint portions, the third brush is arranged on the other side of the pair of joint portions, and a third opposite brush is arranged away from the third brush by 180 degrees.
 
8. The motor according to any one of claims 5 to 7, wherein
a connection member is electrically connected with the commutator bars whose potentials are to be the same with each other.
 




Drawing








































REFERENCES CITED IN THE DESCRIPTION



This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description