Inductor devices – With supporting and/or spacing means between coil and core – Preformed insulation between coil and core
Reexamination Certificate
2001-02-21
2003-07-01
Nguyen, Tuyen T. (Department: 2832)
Inductor devices
With supporting and/or spacing means between coil and core
Preformed insulation between coil and core
C336S192000, C335S289000
Reexamination Certificate
active
06587024
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electromagnetic coil assembly for use in an electromagnetic apparatus, such as an electromagnetic clutch for use in controlling the transmission of power from an automobile engine to a refrigerant compressor in an automobile air conditioning system. More particularly, it relates to the mounting structure for a thermal protection device, electrical wires, and caulking terminals in the electromagnetic coil assembly.
2. Description of Related Art
Referring to
FIGS. 1 and 2
, an electromagnetic coil assembly
4
, which comprises a bobbin
1
and a coil
3
, is known in the art. Bobbin
1
has a toroidal shape having a spool portion, which has an exterior open edge. Coil
3
is formed of electrical wire
2
, which is wound around the spool portion. An electromagnetic coil assembly
4
, for example, is used in an electromagnetic clutch
6
of a compressor
5
in an automobile air conditioning system, as shown in FIG.
3
. Electromagnetic coil assembly
4
may be provided with a thermal protection device
7
, e.g., a thermal fuse or a thermal switch, which is sensitive to high temperatures in electromagnetic clutch
6
. Thermal protection device
7
isolates a power source, such as an automobile engine, to protect electromagnetic clutch
6
and compressor
5
when high temperatures due to friction are generated between the parts in electromagnetic clutch
6
.
Referring again to
FIGS. 1 and 2
, thermal protection device
7
has a pair of leads, a first lead
7
a
and a second lead
7
b
, extending from either end of thermal protection device
7
. An end of first lead
7
a
of thermal protection device
7
is connected to a wire end portion
2
a
of electrical wire
2
through a first caulking terminal
8
. An end of second lead
7
b
of thermal protection device
7
is connected to a third lead
9
, which is connected to the external power source (not shown), through a second caulking terminal
10
. Thermal protection device
7
, first lead
7
a
and second lead
7
b
, wire end portion
2
a
, and third lead
9
are disposed on a first end surface
1
a
of bobbin
1
. A securing member
11
having a groove-shaped cross-section is fixed securely on first end surface
1
a
by adhesives. Thermal protection device
7
is fitted into the groove-shaped portion of securing member
11
. A pair of projection portions
12
a
and
12
b
are formed on first end surface
1
a
. First lead
7
a
and second lead
7
b
are fixeded to projection portions
12
a
and
12
b
, respectively. Consequently, thermal protection device
7
, as well as first caulking terminal
8
and second caulking terminal
10
, is fixed to first end surface
1
a
of bobbin
1
.
As shown in
FIG. 1
, electromagnetic coil assembly
4
is inserted into a core
5
ring
13
having a groove-shaped cross-section and a toroidal shape in plan view, such that thermal protection device
7
on first end surface
1
a
is positioned in an open end of core ring
13
. Thereafter, a resin
14
is poured into the open end of core ring
13
, and electromagnetic coil assembly
4
is fixed within core ring
13
.
In electromagnetic coil assembly
4
, the retention strength of thermal
40
protection device
7
, first caulking terminal
8
, and second caulking terminal
10
within core ring
13
is relatively low. Therefore, resin
14
may enter into the spaces between thermal protection device
7
, first caulking terminal
8
, and second caulking terminal
10
and first end surface
1
a
of bobbin
1
. Consequently, thermal protection device
7
, first caulking terminal
8
, and second caulking terminal
10
may be pushed upward by resin
14
entering into the spaces between these elements, and as a result, these elements may not be covered by resin
14
and may be exposed outside core ring
13
. Thus, when electromagnetic coil assembly
4
disposed in core ring
13
is equipped with the parts, which comprise, for example, electromagnetic clutch
6
, defects or damage may occur at thermal protection device
7
, first caulking terminal
8
, and second caulking terminal
10
.
SUMMARY OF THE INVENTION
An object of the present invention is to reduce or eliminate the above-mentioned defects or damage, which may be encountered in known electromagnetic coil assemblies with thermal protection devices and caulking terminals.
In an embodiment of the present invention, an electromagnetic coil assembly for an electromagnetic apparatus comprises a bobbin, a coil, and a thermal protection device. The bobbin comprises a cylindrical tubular spool, and a pair of annular flanges projecting radially from the spool to form an exterior open edge. The coil is formed of an electrical wire. The electrical wire is wound around the spool between the flanges. The thermal protection device has a first and a second lead wires, each extending from one side thereof. The first lead wire is connected to one end of the electrical wire through a first connecting member. The second lead wire is connected to one end of a third lead wire of an electrical circuit through a second connecting member. The thermal protection device, the first lead wire, the second lead wire, the first connecting member, the second connecting member, and one end of the electrical wire, one end of the third lead wire are disposed and fixed on a first end surface of the bobbin. At least one securing member having a groove-shaped cross-section is fixed, e.g., welded securely or fitted pressedly, on the first end surface of the bobbin. The thermal protection device, the first connecting member, and the second connecting member are covered by the securing member.
Other objects, features, and advantages will be apparent to persons of ordinary skill in the art from the following description of the invention with reference to the accompanying drawings.
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Baker & Botts L.L.P.
Nguyen Tuyen T.
Sanden Corporation
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