Stick-type ignition coil device having thermal stress...

Details Stick-type ignition coil device having thermal stress... Stick-type ignition coil device having thermal stress...

2000-12-22

2002-10-22

Enad, Elvin (Department: 2832)

Inductor devices

With outer casing or housing

C536S096000, C536S124000

Reexamination Certificate

active

06469608

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATION
This application is based on and incorporates herein by reference Japanese Patent Application No. 11-366445 filed Dec. 24, 1999.
BACKGROUND OF THE INVENTION
The present invention relates to a stick-type ignition coil device that is fit in a plug hole of each cylinder of an engine.
A stick-type ignition coil device that is fit in a plug hole of each cylinder of an internal combustion engine is constructed as shown in FIG.
3
. Specifically, the ignition coil device is generally constructed with cylindrical coil casing
11
, a central core
18
, a primary spool
19
, a primary winding
20
wound about the primary spool
19
, a secondary spool
21
and a secondary winding
22
wound about the secondary spool
21
. These components are disposed concentrically. A connector housing
14
is formed with a positioning part
16
and assembled with the coil casing
11
in such a manner that the positioning part
16
holds the central core
18
in central position through a cushion
23
. The coil casing
11
, the connector housing
14
and the spools
19
,
21
are made of resin. An insulating resin
24
is filled in spaces among those components for electrical insulation and fixing.
The ignition coil device repeats to generate heat in high voltage generating operation and radiate heat after the operation. As a result, the insulating resin
24
, the positioning part
16
and the like repeat thermal expansion and contraction. As the positioning part
16
and the insulating resin
24
have different coefficients of thermal expansion, thermal stress exerts from the insulating resin
24
to the positioning part
16
due to temperature changes. The central core
18
and the cushion
23
displace in the downward direction in
FIG. 3
relative to the positioning part
16
due to difference between the coefficients of thermal expansion, when the temperature rises in the ignition coil operation.
As the positioning part
16
is firmly fixed to the insulating resin
24
, the positioning part
16
is restricted from displacing by the insulating resin
24
covering the upper surface of the positioning part
16
and the positioning part
16
does not deform. As a result, the insulating resin layer
24
a
is subjected to pull stress in the upward and downward directions thus causing cracks X in the insulating resin layer
24
a
between the positioning part
16
and the cushion
23
as shown in FIG.
4
. If the cracks X progress in the longitudinal direction along the central core
18
, the electrical insulation between the central core
18
and the secondary winding
22
which generates a high ignition voltage is lessened due to dielectric breakdown Y across the spool
21
.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a stick-type ignition coil device, which reduces generation of cracks and ensures electrical insulation.
According to the present invention, a stick-type ignition coil device for engines comprises a central core, primary and secondary windings, a positioning member disposed to define a position of the central core, a coil casing encasing these components therein, and an insulating resin filled in spaces in the coil casing. A thermal stress releasing member is disposed on the upper surface of the positioning member to release thermal stress which exerts between the positioning member and the insulating resin covering the positioning member.
Preferably, the thermal stress releasing member is made of a material which is less adhesive to the insulating resin and the positioning member. The thermal stress releasing member is larger than an end surface of the central core in size and provided right above the central core.


REFERENCES:
patent: 5870012 (1999-02-01), Sakamaki et al.
patent: 9-35960 (1997-02-01), None

Affiliated with

Also associated with

Rating

Stick-type ignition coil device having thermal stress... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Stick-type ignition coil device having thermal stress..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stick-type ignition coil device having thermal stress... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2987877