Electric motor

Patent metadata

Field	Value
Publication number	US-2016134073-A1
Application number	US-201414900727-A
Country	US
Kind code	A1
Filing date	Jul 10, 2014
Priority date	Jul 11, 2013
Publication date	May 12, 2016
Grant date	—

Abstract

In an electric motor, a brush holder stay ( 33 ) has an opening section through which a commutator ( 23 ) is able to be inserted in a rotary shaft direction (O 1 ), brush holders ( 41 ) extend in the rotary shaft direction (O 1 ) and are formed in a flat spring shape biased toward the inside in a radial direction, base end sections of the brush holders ( 41 ) are supported by the brush holder stay ( 33 ) at intervals in a circumferential direction around the rotary shaft ( 3 ), and brushes ( 31 ) are held by the front end sections of the brush holders ( 41 ).

First claim

1 . An electric motor comprising:
a yoke having a cylindrical section; magnets disposed at an inner circumferential surface of the cylindrical section and having 4 or more magnetic poles; an armature attached to a rotary shaft and rotatable inside the yoke; a commutator attached to the rotary shaft and having a plurality of segments; a plurality of brushes in sliding contact with the segments configured to supply electric power; brush holders holding each of the brushes separately; and a brush holder stay supporting the brush holders, wherein the brush holder stay has an opening section through which the commutator is able to be inserted in an axial direction of the rotary shaft, each of the brush holder extends in the axial direction and is formed in a flat spring shape biased toward the inside in a radial direction perpendicular to the axial direction, and base end sections of the brush holders are supported by the brush holder stay at intervals in a circumferential direction around the rotary shaft, and the brushes are held at the front end sections of the brush holders.

2 . The electric motor according to claim 1 , wherein the brush holder has the base end section disposed at the armature side along the axial direction, and is formed gradually away from the armature toward the front end section.

3 . The electric motor according to claim 1 , wherein, in the segments, the segments configured to be the same potential are short-circuited by a connecting wire,
the brush comprises: a brush for a low speed and a brush for a high speed; and a common brush commonly used for the brush for a low speed and the brush for a high speed, the brush for a low speed and the common brush are disposed at an interval of an electrical angle of 180° in a circumferential direction, and the brush for a high speed is disposed in a second region opposite to a first region in the radial direction with the rotary shaft sandwiched therebetween, the first region being disposed between the brush for a low speed and the common brush in the circumferential direction.

4 . The electric motor according to claim 1 , wherein a connector section is configured to electrically connect the brush and also to connect to the outside is integrally formed with the brush holder stay, and
a distance between the brush for a high speed and the connector section is smaller than a distance from the brush for a low speed and the common brush to the connector section.

5 . The electric motor according to claim 4 , further comprising a noise prevention element disposed between the brushes and the connector section.

6 . The electric motor according to claim 3 , wherein the brush for a high speed has a width in the circumferential direction smaller than that of the brush for a low speed and the common brush.

7 . The electric motor according to claim 1 , comprising:
a speed reduction mechanism having a worm connected to the rotary shaft, and a worm wheel to which an output shaft is fixed, meshed with the worm, and configured to reduce rotation speed of the rotary shaft and to output the reduced rotation from the output shaft; and a gear housing accommodating the speed reduction mechanism and the brush holder stay, wherein a first positioning section configured to perform positioning in the axial direction with respect to the gear housing is formed at the brush holder stay.

8 . The electric motor according to claim 7 , wherein the gear housing has a bottomed cylindrical frame section accommodating the speed reduction mechanism and a bottom plate closing an opening section of the frame section,
a connector section assembled to the gear housing and having a connector terminal connected to the outside and a holder unit at which the brush holder is integrally disposed are provided, a contact plate extending from the connector terminal toward the worm wheel is disposed at the connector section, in the gear housing, a relay unit engaged with the worm wheel to be rotated with the worm wheel and with which the contact plate comes into contact is disposed at the frame section side, and a second positioning section configured to be positioned at the frame section is formed at the relay unit.

9 . The electric motor according to claim 8 , wherein the connector terminal and the contact plate are integrally formed with each other and insert-molded in the connector section.

10 . The electric motor according to claim 8 , wherein the brushes are routed to the connector section via a jumper cable.

11 . The electric motor according to claim 8 , wherein the holder unit is disposed at a position overlapping the gear housing when seen from the axial direction of the rotary shaft.

12 . The electric motor according to claim 1 , wherein an attachment piece is installed at the bottom plate for enabling to attach to a vehicle body or a wiper apparatus.

Assignees

• Mitsuba Corp

Inventors

• Tokizaki Teppei
• Kawashima Yoshichika
• Tamura Natsumi

Classifications

• B60S1/166 Primary

  characterised by the combination of a motor-reduction unit and a mechanism for converting rotary into oscillatory movement · CPC title

• H02K5/145

  Fixedly supported brushes or brush holders, e.g. leaf or leaf-mounted brushes · CPC title

• H02K13/006

  Structural associations of commutators · CPC title

• H01R39/383 Primary

  characterised by the electrical connection to the brush holder · CPC title

• H01R39/40

  enabling brush movement within holder during current collection · CPC title