Wire-wound common-mode choke coil

Details Wire-wound common-mode choke coil Wire-wound common-mode choke coil

2000-01-18

2002-10-29

Enad, Elvin (Department: 2832)

Inductor devices

Winding with terminals, taps, or coil conductor end...

C336S083000, C336S200000, C336S208000

Reexamination Certificate

active

06472969

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to a wire-wound common-mode choke coil used as a noise filter or other component for blocking common mode noise.
2. Description of the Related Art
In
FIG. 8
, a common-mode choke coil for blocking common-mode noise includes a first winding
22
connected between an input terminal electrode
1
a
and an output terminal electrode
2
a
, and a second winding
23
connected between an input terminal electrode
1
b
and an output terminal electrode
2
b
. The first winding
22
and the second winding
23
are bifilar-wound in the same direction on a core member
20
which is made of a magnetic material, such as a ferrite.
FIG. 9
is a bottom perspective view showing the core member
20
of a conventional common-mode choke coil, which includes a winding core
11
which is arranged to accommodate the windings
22
and
23
thereon, and includes square flanges
12
and
13
disposed at both ends of the winding core
11
. Grooves
14
and
15
are formed in the flanges
12
and
13
, respectively, and extend from a side of each flange toward the winding core
11
. With the formation of the grooves
14
and
15
, a pair of legs
12
a
and
12
b
and a pair of legs
13
a
and
13
b
are provided with the grooves
14
and
15
, respectively, between each pair of legs, and the legs support the core member
20
. Terminal electrodes
1
a
,
1
b
,
2
a
, and
2
b
are provided on the ends of the legs
12
a
,
12
b
,
13
a
, and
13
b
, respectively.
In
FIG. 10
shows a conventional coil in which the first and second windings
22
and
23
are wound in a single layer on the winding core
11
of the core member
20
. Ends
22
a
and
22
b
of the first winding
22
and ends
23
a
and
23
b
of the second winding
23
are electrically connected to the terminal electrodes
1
a
and
2
a
and the terminal electrodes
1
b
and
2
b
, respectively.
In the conventional wire-wound common-mode choke coil
10
in
FIG. 10
, a problem occurs in that the bottom edges of the grooves
14
and
15
formed in the flanges of the core member
20
are flush with the periphery of the winding core
11
, and the vertical surfaces of the legs
12
a
,
12
b
,
13
a
, and
13
b
extend perpendicularly relative to the periphery of the winding core
11
. Therefore, when a stress is applied to the legs
12
a
,
12
b
,
13
a
, and
13
b
during winding of the first and second windings
22
and
23
on the core member
20
, the stress is concentrated to the lower parts of the legs
12
a
,
12
b
,
13
a
, and
13
b
, which extends from the periphery of the winding core
11
, thereby breaking the legs
12
a
,
12
b
,
13
a
, or
13
b.
The following is a description of an inspection by image analysis of the first and second windings
22
and
23
in a wound-state, in the common-mode choke coil
10
. The first and second windings
22
and
23
are visible between two legs of the core member
20
, for example, the legs
13
a
and
13
b
. When the windings are viewed along arrow A in
FIG. 10
, it is possible to determine whether the windings
22
and
23
are properly wound on the winding core
11
by analyzing the image obtained.
In the image analysis, only one layer of windings, for example, a layer of the first winding
22
, is visible through the groove
15
between the legs
13
a
and
13
b
of the core member
20
, as shown in
FIG. 11
, when the first and second windings
22
and
23
are properly wound on the winding core
11
, as shown in FIG.
10
. On the other hand, overlapped windings
22
and
23
are identified through the groove
15
between the legs
13
a
and
13
b
, as shown in
FIG. 13
, when the first and second windings
22
and
23
are improperly wound, as shown in FIG.
12
. Therefore, the wound-state of the first and second windings
22
and
23
is detected by analyzing the image of the first and second windings
22
and
23
visible through the groove
15
, and thus, it is determined whether the first and second windings
22
and
23
are properly arranged.
However, a problem in a conventional wire-wound common-mode choke coil is that the result of the detection of the wound-state of the first and second windings
22
and
23
visible through the groove
15
varies according to the color and the diameter of the wire, the overlapping position, the overlapped state, or other factors and characteristics of the windings
22
and
23
. Therefore, the inspection of the wound-state via image analysis is difficult and not reliable in a conventional wire-wound common-mode choke coil.
SUMMARY OF THE INVENTION
To overcome the problems described above, preferred embodiments of the present invention provide a wire-wound common-mode choke coil in which a core member is provided with a sufficient mechanical-strength and is constructed such that a reliable inspection of the wound state of windings on the core member can be performed.
According to one preferred embodiment of the present invention, a wirewound common-mode choke coil preferably includes a core member having a winding core, flanges disposed at both ends of the winding core, a plurality of legs located at both ends of grooves provided at the flanges, and terminal electrodes, each of the terminal electrodes being provided at the end of each of the legs and connected to ends of a plurality of windings wound on the winding core. At least four terminal electrodes are provided in the wire-wound common-mode choke coil. Bottom surfaces of the grooves are spaced from the periphery of the winding core, and protrusions are provided at ends of the winding core. The flank of the protrusions are preferably gradually elevated toward the flanges.
The protrusions are preferably provided at the lower portions of the legs and protrude out from the winding core, and also at the bottom surfaces of the grooves, thereby improving the mechanical strength of the legs and alleviating stress concentration to the lower portions of the legs, protruding out from the winding core.
The mechanical strength of the legs may be greater and the stress concentration may be alleviated by arranging protrusions which protrude out from the periphery of the winding core which extends toward the legs, higher than the bottom surface of the grooves, thereby increasing the cross-sectional areas of the protrusions.
The determination as to whether the windings are properly arranged may be performed simply by determining whether or not the windings are visible through one of the grooves. The bottom surface of the grooves is elevated from the periphery of the winding core by about 1.0 to about 1.5 times the diameter of the wire of the windings. The windings are not visible through a groove when the windings are properly wound, and the windings are visible through the groove when the windings are improperly wound.
Other features, elements and advantages of the present invention will become more apparent from the detailed description of preferred embodiments of the present invention below with reference to the attached drawings.


REFERENCES:
patent: 6242996 (2001-06-01), Sato et al.
patent: 62-152413 (1987-09-01), None
patent: 2-10704 (1990-01-01), None
patent: 5-87913 (1993-04-01), None
patent: 5-62022 (1993-08-01), None
patent: 10-116740 (1998-05-01), None

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