Inductor devices – With outer casing or housing – Potted type
Reexamination Certificate
2000-12-14
2002-09-24
Mai, Anh (Department: 2852)
Inductor devices
With outer casing or housing
Potted type
C336S090000, C336S092000
Reexamination Certificate
active
06456181
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the structure of an ignition coil to supply the high voltage to an ignition plug.
For the ignition coil used in the recent internal combustion engine for the automobile, there is a conflicting requirement which is the downsizing and the increasing of the output for corresponding to a lean-burn engine considering about the global atmosphere.
Among them, the ignition coil to directly supply the high voltage to the ignition plug, has advantages that the space above the engine head can be reduced because the a portion or an almost portion of the ignition coil is accommodated in a plug hole of the engine head, the generation of the noise at the time of the ignition which has a bad influence on the electrical equipments, is small because the high voltage is directly supplied to the ignition plug and a wire to transmit the high voltage to the ignition plug such as a high tension cable to directly supply the high voltage to the ignition plug, is not necessary, and the transmission loss of the ignition energy to the ignition plug is small, and therefore, it is used for many engines.
A longitudinal sectional view showing the conventional ignition coil to directly supply the high voltage to the ignition plug is shown in FIG.
4
. Conventionally, in an upper accommodation portion
11
b
of a case
11
of the ignition coil to directly supply the high voltage to the ignition plug, a primary voltage input portion
12
, or depending on the case, an igniter
13
to turn on-off the primary current is accommodated, and inside the case
11
, a central iron core
18
on which magnets
21
to generate the magnetic flux in the direction reverse to the magnetic flux generated in a primary coil
15
in order to suppress the saturation of the magnetic flux of the iron core, are mounted, on its both ends, is accommodated, and a secondary coil
17
in which a secondary copper wire is wound around a secondary bobbin
16
, a primary coil
15
in which a primary copper wire is wound around a primary bobbin
14
, and a sheath iron core
19
which is formed into the cylindrical-shape, and has a cutout portion on a portion of its circular periphery, are arranged in their order, coaxially with the central iron core
18
, and a secondary high voltage terminal
22
is provided on the bottom portion of the case
11
, and the secondary high voltage terminal
22
is electrically connected to the secondary coil and a spring
23
in a high voltage tower portion
11
a
provided in the case
11
, and from the opening portion of the upper portion of the case
11
, epoxy resin is filled in the case, hardened, and the case is sealed in the insulation. Further, in the high voltage tower portion
11
a
, a protector
25
is provided so that the high voltage does not leak to a metallic portion such as a plug hole, not shown, and at the time of operation of the ignition coil, the primary current is inputted from the primary voltage input portion
12
, and it flows to the primary coil
15
, and the magnetic energy generated in the primary coil
15
is transmitted through the central iron core
18
and the sheath iron core
19
, and the high voltage corresponding to the winding ratio of the primary coil
15
and the secondary coil
17
is generated in the secondary coil
17
. The generated high voltage passes through the secondary high voltage terminal
22
from the secondary coil, and through the spring
23
, it is sent to the ignition plug, not shown, connected to the spring
23
.
However, in the conventional technology, as shown in
FIG. 5
, because the secondary coil
17
coaxially arranged with the central iron core
18
in the case
11
, is housed in the primary coil
15
coaxially arranged in the same manner, and the insulation of the high voltage output side of the secondary coil
17
is made by filling and hardening the insulation material such as epoxy resins, the epoxy resin is peeled from each of members by the aging thermal stress, and specifically when the primary bobbin
14
is peeled in the vicinity of the high voltage portion of the secondary coil
17
, the high voltage generated in the secondary coil
17
leaks in the space formed by the peeling, and the high voltage is short-circuited to the low voltage portion such as the primary coil
15
in such a manner that the high voltage creeps along the surface of the member, and it causes the disadvantage which results in the dielectric breakdown.
Further, as the ignition coil to generate the high voltage energy, there are methods in which the winding number of the primary coil
15
and the secondary coil
17
is kept as it is, and the diameter of the wound coil is increased, and the electric resistance of these coils is reduced, or the outer shape of the coil is increased in such a manner that the sectional area of the iron core is increased and the efficiency of the magnetic circuit is increased, however, for the cylindrical type ignition coil which is a type to be housed in the plug hole whose diameter is generally called to be about 20 to 35 mm, and in which the restriction of the dimensions is severe, it is difficult that the primary coil
15
, secondary coil
17
, central iron core
18
, sheath iron core
19
, and igniter
13
are housed in the case
11
, and the above method is adopted.
Further, even when the ignition coil is not the type which is housed in the plug hole, there is a requirement of the size and weight reduction for the ignition coil, from points of attachment property, oscillation property, and consumption energy.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to solve the above problems and to provide a long life and small sized ignition coil.
In order to attain the above object, the structure of the ignition coil to directly supply the high voltage to the ignition plug, is changed from the conventional one. The ignition coil of the present invention is an ignition coil which is characterized in that: the central iron core, and the secondary coil in which the secondary copper wire is coaxially wound around the central iron core, are housed in the case, and the primary coil in which the primary copper wire is wound around the outside of the case, coaxially with the central iron core in the same manner, and the sheath iron core is arranged outside these central iron core, secondary coil, case and primary coil.
Further, the ignition coil of the present invention may also be an ignition coil which is characterized in that the heat resistive insulation material is wound to protect the primary coil, and the heat resistive insulation material is wound, and further, it may be characterized in that the heat resistive insulation material is mounted on the outside of sheath iron core of the ignition coil, and as the heat resistive insulation material, the insulation tape, heat contraction tube, fluoric-rubber, or silicon may be used.
When the above solving means is used, the disadvantage in which the secondary output high voltage flows and leaks in the primary coil
15
in the vicinity of the peeled portion, in the epoxy resin peeling from the primary bobbin
14
and the secondary bobbin
16
inside the case
11
by the aging deterioration of the conventional ignition coil, is not generated because the secondary coil
17
and the primary coil
15
are partitioned from each other, when the secondary coil
17
is housed in the case
11
, and the primary winding is wound around the outside of the case.
Further, when the primary bobbin portion
14
a
is provided in the case
11
, the wall thickness portion of the conventional primary bobbin
14
is abolished, and in its space portion, the diameter of the winding can be increased, or the sectional area of the sheath iron core
19
can be increased, and the secondary output energy can be increased, and when the diameter of the winding or the sectional area of the sheath iron core
19
is the same as the conventional one, the outer shape of the ignition coil can be reduced to the smaller one by the amount of the wall thic
Diamond Electric Mfg. Co. Ltd.
Mai Anh
McGinn & Gibb PLLC
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