U.S. patent application number 09/906069 was filed with the patent office on 2001-12-06 for direct current motor.
This patent application is currently assigned to MITSUBISHI DENKI KABUSHIKE KAISHA. Invention is credited to Fujita, Youichi, Kawamura, Satoshi, Miyake, Toshihiko, Miyoshi, Sotsuo.
Application Number | 20010048252 09/906069 |
Document ID | / |
Family ID | 14237328 |
Filed Date | 2001-12-06 |
United States Patent
Application |
20010048252 |
Kind Code |
A1 |
Fujita, Youichi ; et
al. |
December 6, 2001 |
Direct current motor
Abstract
A direct current motor according to the present invention is
provided with a stator 2 in which coils 4 corresponding to N phases
are arranged almost at equal intervals in a circle-circumferential
direction of stator cores 3, a rotor 8 in which a plurality of
permanent magnets 9 are respectively arranged at positions
corresponding to the coils 4 of the stator 2, and a current
carrying device, having a commutator 11, for commutating direct
current supplied from a power source to N-phase current in
cooperation with the rotor 8 and carrying the N-phase current to
each coil of the stator 2. In the internal space of the current
carrying device, a plurality of noise eliminating members 23
connected with a plurality of brush holding plates corresponding to
the coil phases are arranged.
Inventors: |
Fujita, Youichi; (Tokyo,
JP) ; Miyoshi, Sotsuo; (Tokyo, JP) ; Miyake,
Toshihiko; (Tokyo, JP) ; Kawamura, Satoshi;
(Tokyo, JP) |
Correspondence
Address: |
SUGHRUE, MION, ZINN, MACPEAK & SEAS
2100 Pennsylvania Avenue, N.W.
Washington
DC
20037
US
|
Assignee: |
MITSUBISHI DENKI KABUSHIKE
KAISHA
|
Family ID: |
14237328 |
Appl. No.: |
09/906069 |
Filed: |
July 17, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09906069 |
Jul 17, 2001 |
|
|
|
PCT/JP99/06455 |
Nov 18, 1999 |
|
|
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Current U.S.
Class: |
310/51 |
Current CPC
Class: |
H02K 11/026 20130101;
H01R 39/06 20130101; H01R 39/64 20130101; H02K 23/62 20130101 |
Class at
Publication: |
310/51 |
International
Class: |
H02K 005/24 |
Claims
What is claimed is:
1. A direct current motor, comprising a stator in which coils
corresponding to N phases are arranged almost at equal intervals in
a circle-circumferential direction of stator cores; a rotor in
which a plurality of permanent magnets are respectively arranged at
positions corresponding to the coils of the stator; and a current
carrying device for commutating direct current supplied from a
power source to N-phase current in cooperation with the rotor and
carrying the N-phase current to each coil of the stator,
characterized in that the direct current motor further comprises a
noise eliminating member arranged in an internal space of the
current carrying device to be connected with the coils of two coil
phases.
2. A direct current motor according to claim 1, wherein the noise
eliminating members are fixed to the current carrying device by
adhesive material or by caulking.
3. A direct current motor according to claim 1, wherein the current
carrying device comprises a plurality of plates, each of which
corresponds to one coil phase of the stator, and one noise
eliminating member is connected with each pair of plates adjacent
to each other.
Description
CROSS-REFERENCE TO THE RELATED APPLICATION
[0001] This application is a continuation of International
Application No. PCT/JP99/06455, whose International filing date is
Nov. 18, 1999, the disclosures of which Application are
incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a direct current motor
appropriate to an exhaust gas recycle valve device in which the
direct current motor is used for a vehicle height adjusting device
or an exhaust gas recycle system mounted in a vehicle.
[0004] 2. Description of Related Art
[0005] Published Unexamined Japanese Patent Application No.
H11-168851 (1999) discloses a known direct current motor. This type
direct current motor is principally composed of a rotor, a stator
functioning as a case for surrounding the rotor and a commutator.
Coils are arranged in the rotor, a plurality of permanent magnets
arranged at equal intervals are tightly fitted to an inner
peripheral face of the rotor, and the commutator can be coaxially
rotated together with the rotor. Also, noise eliminating parts such
as condensers, varistors and the like are arranged to eliminate
noise generated in a motor drive operation. For this reason, these
components are arranged between terminals functioning as an
electric power supplying unit of the direct current motor.
[0006] However, because the conventional direct current motor has
the above-described structure, there is a problem that the noise
generated in the motor drive operation cannot be sufficiently
eliminated.
SUMMARY OF THE INVENTION
[0007] An object of the present invention is to provide, with due
consideration to the drawbacks of the conventional direct current
motor, a direct current motor in which a noise eliminating element
is arranged to reliably eliminate noise generated in a motor drive
operation.
DISCLOSURE OF THE INVENTION
[0008] A direct current motor of the present invention comprises a
stator in which coils corresponding to N phases are arranged almost
at equal intervals in a circle-circumferential direction of stator
cores, a rotor in which a plurality of permanent magnets are
respectively arranged at positions corresponding to the coils of
the stator, and a current carrying device for commutating direct
current supplied from a power source to N-phase current in
cooperation with the rotor and carrying the N-phase current to each
coil of the stator. The direct current motor further comprises a
noise eliminating member arranged in an internal space of the
current carrying device to be connected with the coils of two coil
phases. Accordingly, noise generated in a motor operation time can
be reliably eliminated by the noise eliminating members.
[0009] In the direct current motor of the present invention, the
noise eliminating members are fixed to the current carrying device
by adhesive material or by caulking. Therefore, the noise
eliminating members can be easily fitted to the current carrying
device.
[0010] In the direct current motor of the present invention, the
current carrying device comprises a plurality of plates, each of
which corresponds to one coil phase of the stator, and one noise
eliminating member is connected with each pair of plates adjacent
to each other. Therefore, noise generated in a motor operation time
can be reliably eliminated by the noise eliminating members, and a
space between each pair of plates can be effectively used.
Therefore, a small-sized direct current motor can be
manufactured.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a sectional view showing the structure of a direct
current motor according to a first embodiment of the present
invention.
[0012] FIG. 2A and FIG. 2B are plan views of the direct current
motor shown in FIG. 1 and show a manufacturing method of a stator
of the direct current motor.
[0013] FIG. 3 is a diagonal view showing the structure of a
commutator and a plurality of strip rings of a current carrying
device shown in FIG. 1.
[0014] FIG. 4 is a plan view showing a plurality of noise
eliminating members arranged at prescribed positions of a stator
core of the direct current motor shown in FIG. 1.
[0015] FIG. 5 is a sectional view of connection between each noise
eliminating member shown in FIG. 4 and a motor brush holding plate
arranged in the stator core as an example.
[0016] FIG. 6 is a sectional view showing a current flow in the
current carrying device of the direct current motor shown in FIG.
1.
[0017] FIG. 7 is a sectional view of connection between each noise
eliminating member shown in FIG. 4 and the corresponding motor
brush holding plate arranged in the stator core as another
example.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] The invention will now be described with reference to the
accompanying drawings.
EMBODIMENT 1
[0019] FIG. 1 is a sectional view showing the structure of a direct
current motor according to a first embodiment of the present
invention. FIG. 2A and FIG. 2B are plan views of the direct current
motor shown in FIG. 1 and show a manufacturing method of a stator
of the direct current motor. FIG. 3 is a diagonal view showing the
structure of a commutator and a plurality of strip rings of a
current carrying device shown in FIG. 1. FIG. 4 is a plan view
showing a plurality of noise eliminating members arranged at
prescribed positions of a stator core of the direct current motor
shown in FIG. 1. FIG. 5 is a sectional view of connection between
each noise eliminating member shown in FIG. 4 and a motor brush
holding plate arranged in the stator core as an example. FIG. 6 is
a sectional view showing a current flow in the current carrying
device of the direct current motor shown in FIG. 1.
[0020] In FIG. 1 to FIG. 6, a numeral number 1 indicates a motor
case formed of resin material. 2 indicates a stator integrally
formed with the motor case 1 by resin molding. As shown in FIG. 2A,
each of a plurality of stator cores 3 of the stator 2 is
principally composed of a plurality of core pieces 3a, a plurality
of magnet teeth 3b respectively projected from a face of the
corresponding core piece 3a and a plurality of thin-walled portions
3c respectively connecting two core pieces 3a adjacent to each
other. N coils 4 (N is an integral number higher than 1) are
respectively wounded on N groups of magnet teeth 3b by using a
winding machine (not shown). Thereafter, as shown in FIG. 2B, each
thin-walled portion 3c is folded so as to form each stator core 3
in a cylinder shape.
[0021] In FIG. 1, 5 is a flange member fitted to one end of the
motor case 1, and a boss portion 5a for supporting a bearing 6 is
protruded from the central portion of the flange member 5. 7
indicates a bearing which is supported by the other side of the
motor case 1, and the bearing 7 is arranged coaxially with the
bearing 6. 8 indicates a rotor of which both ends are supported by
the bearings 6 and 7 respectively. A plurality of permanent magnet
poles 9 are arranged on the outer peripheral face of the rotor 8,
and each permanent magnet pole 9 is placed at a position
corresponding to the corresponding coil 4 of the stator 2. A motor
shaft 8a is protruded from one end of the rotor 8 supported by the
bearing 6.
[0022] In FIG. 1 and FIG. 3, 10 indicates a circular disk which is
fixed to the other end of the rotor 8 so as to be rotated together
with the rotor 8. 11 indicates a commutator which is formed by
dividing a central ring portion of the circular disk 10 into a
plurality of commutator pieces 11a arranged in a
circle-circumferential direction of the central ring portion.
Direct current supplied from a power source (not shown) is
commutated in the commutator pieces 11a to obtain an N-phase
current corresponding to N coil phases. 12 indicates a plurality of
slip rings which are formed by concentrically and annularly
dividing a portion of the circular disk 10 placed on the outer
circumference side of the commutator 11 into N portions (three
portions in FIG. 3). 13 indicates a bracket fitted to the other end
of the motor case 1. 14 indicates a pair of first brushes which are
supported by the bracket 13 so as to be insulated from the bracket
13. The top end of each first brush 14 comes in contact with each
commutator piece 11a of the commutator 11 under a prescribed
pressure so as to be able to slide on the commutator piece 11a. 15
indicates a plurality of second brushes which are supported by the
bracket 13 so as to be insulated from the bracket 13. The top end
of each second brush 15 comes in contact with the corresponding
slip ring 12 under a prescribed pressure so as to be able to slide
on the slip ring 12. A current carrying unit 16 is composed of the
circular disk 10, the commutator 11, the slip rings 12, the bracket
13, the first brushes 14 and the second brushes 15.
[0023] In FIG. 4, 20 indicates each of a plurality of plate spring
members. Each of the first brushes 14 and the second brushes 15 is
supported on a top portion of one plate spring member 20, each
brush 14 or 15 is pushed toward a surface of one commutator piece
11a or a surface of one slip ring 12 by the corresponding plate
spring member 20 so as to be able to slide on the surface. 21
indicates each of a plurality of brush holding plates for
respectively holding a base end portion of one plate spring member
20. Each brush holding plate 21 corresponds to one coil phase of
the stator 2. The pair of first brushes 14 are fixed to one brush
holding plate 21 through one plate spring member 20, and the three
second brushes 15 are respectively fixed to the other brush holding
plates 21 through the plate spring members 20. Therefore, in this
first embodiment, there are four brush holding plates 21. These
brush holding plates 21 are separated from each other through four
separation portions 21a and are fixed to an inner peripheral
surface of a brush holding plate fixing member 22 of an annular
shape. Therefore, all the brush holding plates 21 are electrically
insulated from each other and are mechanically independent from
each other.
[0024] Also, a cut hole 21 is formed in one brush holding plate 21
to which the pair of first brushes 14 are fixed, and the first
brushes 14 are electrically insulated from each other by the cut
hole 21.
[0025] A plurality of noise eliminating members 23 are fitted to
the brush holding plates 21 to eliminate noise generated in the
brushes 14 and 15 in a motor operation time. Each noise eliminating
member 23 is, for example, formed of a condenser or a varistor or
the like. Two connection terminals 24 of each noise eliminating
member 23 are respectively inserted into two connection holes 21c
of two brush holding plates 21 different from each other, and each
connection terminal 24 is fixed to the corresponding brush holding
plate 21 by solder 25 (refer to FIG. 5). That is, each noise
eliminating member 23 is connected with two corresponding brush
holding plates 21 electrically insulated from each other so as to
stride over the separation portion 21a arranged between the brush
holding plates 21. Because each brush holding plate 21 corresponds
to one coil phase as is described above, each noise eliminating
member 23 is substantially connected with one pair of coils 4
corresponding to two coil phases.
[0026] Next, an operation of the direct current motor having the
structure described above is described.
[0027] Initially, as shown in FIG. 6, when direct current supplied
from a power source (not shown) flows into one of the first brushes
14, the direct current is commutated in one commutator piece 11 of
the commutator 11, passes through one strip ring 12 and is supplied
to the stator 2 through one second brush 15. After the commutated
current passes through one coil 4, the commutated current passes
through another second brush 15, another strip ring 12 and the
other commutator piece 11 of the commutator 11 in that order, and
the commutated current flows out to the power source though the
other first brush 14. In this case, a rotational force is generated
in the rotor 8 by the interaction between magnetic flux generated
in the coil 4, through which the current flows, and the permanent
magnetic poles 9 of the rotor 8, and the circular disk 10 is
rotated together with the rotor 8 by the rotational force
Therefore, the pair of commutator pieces 11 coming in contact with
the pair of first brushes 14 are changed to another pair of
commutator pieces 11, and the coil 4, through which the commutated
current flows, is changed to another coil 4. As a result, the rotor
8 is continuously rotated.
[0028] In this case, because two coils 4 of two coil phases are
connected with each other through the corresponding noise
eliminating member 23, noise generated in the brushes 14 and 15 and
the like can be reliably eliminated by the noise eliminating
members 23.
[0029] Accordingly, in the first embodiment, because the noise
eliminating members 23 are arranged in the neighborhood of a noise
generation source such as coils 4, the noise can be efficiently and
reliably eliminated.
[0030] Also, in the first embodiment, because the connection
terminals 24 of the noise eliminating members 23 are fixed to the
brush holding plates 21 by solder 25, the fixing operations of the
noise eliminating members 23 can be easily performed, a
manufacturing efficiency of the direct current motor can be
heightened, and a manufacturing cost of the direct current motor
can be reduced.
EMBODIMENT 2
[0031] FIG. 7 is a sectional view of connection between each noise
eliminating member shown in FIG. 4 and the corresponding motor
brush holding plate arranged in the stator core as another example.
The constitutional elements of a direct current motor according to
a second embodiment, which are the same as or equivalent to those
according to the first embodiment, are indicated by the same
reference numerals as those of the first embodiment, and additional
description of the constitutional elements is omitted.
[0032] As shown in FIG. 7, features of a direct current motor
according to the second embodiment are in that the connection
terminals 24 of the noise eliminating members 23 are respectively
caulked at caulking portions 21d of the brush holding plates 21 to
fix the connection terminals 24 to the brush holding plates 21.
[0033] Accordingly, in the second embodiment, because the
connection terminals 24 of the noise eliminating members 23 are
caulked and fixed, not only the noise can be efficiently and
reliably eliminated, but also the fixing operations of the noise
eliminating members 23 can be easily performed, a manufacturing
efficiency of the direct current motor can be heightened, and a
manufacturing cost of the direct current motor can be reduced.
[0034] In the first and second embodiments, the noise eliminating
members 23 are arranged in three of the four brush holding plates
21. However, it is applicable that one noise eliminating member 23
be arranged in each pair of brush holding plates 21 adjacent to
each other. In this case, noise generated in the motor operation
time can be more reliably eliminated by the noise eliminating
members 23, and a space between each pair of brush holding plates
21 can be effectively used. Therefore, a small-sized direct current
motor can be manufactured.
INDUSTRIAL APPLICABILITY
[0035] As is described above, in the direct current motor according
to the present invention, because the noise generated in the motor
operation time can be reliably eliminated by arranging the noise
eliminating member between each pair of coils of two coil phases,
the motor can be prevented from being erroneously operated due to
the noise. Also, because the noise eliminating members are fixed by
solder or caulking, the fixing operations of the noise eliminating
members can be easily performed, a manufacturing efficiency of the
direct current motor can be heightened, and a manufacturing cost of
the direct current motor can be reduced. In addition, because one
noise eliminating member is arranged in each pair of brush holding
plates adjacent to each other, noise generated in the motor
operation time can be more reliably eliminated by the noise
eliminating members, and a space between each pair of brush holding
plates can be effectively used. Therefore, a small-sized direct
current motor can be manufactured.
* * * * *