Inductor devices – With outer casing or housing
Reexamination Certificate
2002-10-29
2004-04-13
Donovan, Lincoln (Department: 2832)
Inductor devices
With outer casing or housing
C336S092000, C336S096000, C336S192000, C336S198000, C123S634000, C123S635000
Reexamination Certificate
active
06720854
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based on and incorporates herein by reference Japanese Patent Application No. 2001-333194 filled on Oct. 30, 2001.
FILED OF THE INVENTION
The present invention relates to an ignition coil, which can be directly installed in a plug hole of each cylinder of an engine.
BACK GROUND OF THE INVENTION
An ignition coil generates a high voltage caused by the mutual induction for an ignition plug. For example, an ignition coil disclosed in U.S. Pat. No. 6,208,231 B1 (JP-A-11-111545) is shown in FIG.
7
.
The ignition coil
100
shown in
FIG. 7
is inserted in a plug hole of an engine. A case
117
has a cylindrical shape and forms an outside shell of the ignition coil
100
. In the center of the case
117
, a center core
101
that is like a pole is installed. Around the center core
101
, a secondary cylindrical spool
102
is installed. A secondary coil
107
is wound around the secondary cylindrical spool
102
. A primary cylindrical spool
113
is installed around the secondary coil
107
. A primary coil
115
is wound around the primary spool
113
. The inside of the case
117
is filled with an epoxy resin
110
to keep the insulation between the above members, and the epoxy resin
110
glues the members to each other.
However, the coefficient of linear expansion of the members stored in the case
117
is different from that of the epoxy resin
110
. Therefore, the members exert a thermal stress to each other by the compressibility or the expansion of the members caused by transition of a temperature. For example, the inner members in the case
2
such as the secondary spool
102
and the central core
101
are especially influenced by the thermal stress.
Therefore, in the ignition coil
100
, the central core
101
is covered with a stress relaxation member
105
. The stress relaxation member
105
is made of a lubber material and possesses the elasticity. By the elasticity, the stress relaxation member
105
can deform, and the thermal stress between the central core
101
and the epoxy resin
110
is relieved.
In the ignition coil
100
, the primary spool
113
is covered with a thin layer of a film
114
. The film
114
is made of a PET material, so that the adhesion to the epoxy resin
110
is weak. Therefore, the primary spool
113
and the primary coil
115
can be separated easily. By the separation, the thermal stress from the primary coil
115
to the primary spool
113
, that is from the outer side to the inner side, is cut off.
Consequently, the diameter of the coil
100
is large. Because, the stress relaxation member
105
should be placed around the central core
101
, and the thin layer of a film should be covered around the primary spool
113
. That is, the diameter of the ignition coil
100
is limited by the diameter of the plug hole in its design.
Furthermore, the number of the members is large because the stress relaxation member
105
and the thin layer film
114
are placed. Therefore, the manufacturing cost is high. The manufacturing process is complex because the process to cover the central core
101
with a thin layer of a film is necessary.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved ignition coil.
According to the present invention, an ignition coil is formed to have an air layer as an insulator instead of an insulated resin in a gap between a central core and an inner spool or a gap between an outer spool and a case.
REFERENCES:
patent: 5778863 (1998-07-01), Oosuka et al.
patent: 6208231 (2001-03-01), Oosuka et al.
Nagata Takashi
Wada Jyun-ichi
Denso Corporation
Donovan Lincoln
Nixon & Vanderhye PC
Poker Jennifer A.
LandOfFree
Ignition coil having air layers as insulators and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ignition coil having air layers as insulators and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ignition coil having air layers as insulators and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3241490