Coil bobbin for current transformer

Details Coil bobbin for current transformer Coil bobbin for current transformer

2000-11-14

2003-01-14

Donovan, Lincoln (Department: 2832)

Inductor devices

With supporting and/or spacing means between coil and core

Preformed insulation between coil and core

C336S192000, C336S198000, C336S208000

Reexamination Certificate

active

06507261

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a coil bobbin for a current transformer, which is incorporated into a microwave oven, an air conditioner, an electromagnetic cooking device or the like so as to be used in an electric current detecting portion of a circuit in a machine.
2. Description of Related Art
Conventionally, as shown in
FIG. 8
, this kind of current transformer is, for example, configured so as to have a primary coil
20
for detecting electric current, a coil bobbin
21
into which the primary coil
20
is incorporated, a secondary coil
22
wound around a winding drum of the coil bobbin
21
, pin terminals
23
to which lead wires of the secondary coil
22
are connected, and a core
24
incorporated into the coil bobbin
21
including the primary coil
20
and the secondary coil
22
, or the like.
In this current transformer, the primary coil
20
is formed from a thick CP wire or a copper wire to be bent in substantially U-shape, and inserted into a through hole
25
of the coil bobbin
21
to be incorporated into the coil bobbin
21
.
In this case, for example, adhesive is used for fixing the primary coil
20
to the coil bobbin
21
.
Alternatively, an eyelet
26
is mounted on each a pair of legs
20
a
of the primary coil
20
, protruding from the bottom surface of the coil bobbin
21
.
Another alternative is molding the primary coil
20
at the same time as molding the coil bobbin
21
.
Using adhesive for fixing the primary coil
20
to the coil bobbin
21
has such defects that it takes too long in working process and that work control is hard to carry out.
Using the eyelets
26
has such defects that it causes an increase in the number of components and therefore in cost, and that a step of incorporating them is required.
Molding the primary coil
20
at the same time as molding the coil bobbin
21
has also such a defect that the molded component is expensive.
The present invention is achieved in view of the above and has its object to provide a coil bobbin for a current transformer which requires no adhesive or eyelets, and enables easy fixing of the primary coil to the coil bobbin without an increase in cost.
SUMMARY OF THE INVENTION
The present invention attains the above-described object according to a configuration wherein:
a coil bobbin
1
is formed with a primary coil mounting portion
7
and a primary coil fixing portion
8
at an outer surface of one of flanges
4
so as to protrude outwardly;
through holes
9
,
9
′ are formed at both sides of the primary coil mounting portion
7
and the primary coil fixing portion
8
respectively, and a pair of legs
3
a
of a primary coil
3
for detecting electric current extend through the through holes
9
,
9
′;
the primary coil fixing portion
8
is formed with a window
12
into which a jig is inserted;
the window
12
is formed with concave fixing portions
12
a
,
each of the legs
3
a
of the primary coil
3
is inserted into the through hole
9
of the primary coil mounting portion
7
, the window
12
and the through hole
9
′ of primary coil fixing portion
8
, respectively; and
each of the legs
3
a
positioned in the window
12
is bent by the jig toward each of the fixing portions
12
a
to be fixed thereto.
In this case, the fixing portions
12
a
are formed at both side surfaces of the window
12
.
Alternatively, the window
12
is formed, at a center thereof, with a column
8
a
, which is formed, at both side surfaces thereof, with the fixing portions
12
a.
Alternatively, the window
12
is formed, at an inner surface thereof, with the fixing portions
12
a.
In addition, positioning members
10
for positioning the primary coil
3
are formed at a top surface of the primary coil mounting portion
7
, and a wall
11
formed at each of both ends of the primary coil mounting portion
7
.
Moreover, the jig
14
is formed with a protrusion
14
b
,
14
c
,
14
d
whereby each leg
3
a
mounted to the coil bobbin
1
and positioned in the window
12
is partly urged to be bent.
Furthermore, a top of the jig
14
is bent in substantially L-shape to be formed, at its bent portion
14
a
, with the protrusion
14
b
,
14
c
,
14
d
in substantially V-shape.


REFERENCES:
patent: 4010435 (1977-03-01), Shigehara et al.
patent: 4617543 (1986-10-01), Akachi
patent: 002333646 (1999-07-01), None
patent: 03180009 (1991-08-01), None
patent: 4-105525 (1992-09-01), None

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