Internal-combustion engines – High tension ignition system – Specific coil location
Reexamination Certificate
1999-10-18
2001-02-27
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
High tension ignition system
Specific coil location
C123S634000, C123S189000, C439S127000
Reexamination Certificate
active
06192873
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims benefit of priority of Japanese Patent Application No. Hei-10-300926 filed on Oct. 22, 1998, the content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ignition coil, a high tension terminal of which is electrically connected to a spark plug via a spring.
2. Description of Related Art
It is generally known to directly connect a stick-type ignition coil to a spark plug via a spring to make electrical connection therebetween. A high tension case containing a high tension terminal and a spring is connected to a bottom end of an ignition coil. Both the high tension terminal and the spring are assembled and supported in the case before the ignition coil is connected to the spark plug. When the ignition coil is connected to the spark plug, the spring is compressed and contacts the high tension terminal, thereby making electrical connection between the ignition coil and the spark plug. Since the high tension terminal and the spring are supported at the same position in the case, there is a possibility that the spring is jammed between the high tension terminal and the case when the spring is compressed. If that happens, the spring is improperly deformed and may be broken.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-mentioned problem, and an object of the present invention is to provide an improved ignition coil in which the spring and the high tension terminal are separately supported in the high tension case before the ignition coil is connected to the spark plug, and the spring is properly compressed when the ignition coil is connected to the spark plug, thereby avoiding the spring from being jammed between the high tension terminal and the case.
A stick-type ignition coil is composed of a high tension generating portion and a high tension case in which a high tension terminal connected to the high tension generating portion and a spring for electrically connecting the ignition coil to a spark plug are housed. The high tension case is made of resin and integrally connected to the bottom part of the high tension generating portion. The high tension case is generally cylinder-shaped and includes a boss formed therein for supporting the high tension terminal and the spring.
In the process of assembling the high tension case, the spring is first inserted into the high tension case and then the high tension terminal is inserted. Both the spring and the high tension terminal are designed so that the they can be assembled to the high tension case from the upper opening thereof. A first shoulder for supporting the high tension terminal thereon and a second shoulder for supporting the spring thereon are formed on the supporting boss. The spark plug is connected to the ignition coil by inserting the spark plug into the high tension case from the bottom opening thereof. When the spark plug is inserted, the spring is compressed by the spark plug and contacts the high tension terminal, thus making electrical connection for supplying high tension to the spark plug. In short, the spring is held in the high tension case at an axially separate position from the high tension terminal before the spark plug is inserted, and the spring is compressed and contacts the high tension terminal when the spark plug is inserted into the high tension case.
Thus, the spring is properly compressed without being distorted or jammed between the high tension terminal and the high tension case when the spark plug is connected to the ignition coil. In addition, both of the spring and the high tension terminal can be inserted into the high tension case from the same direction in the assembling process, thereby simplifying the assembling process.
The supporting boss may be designed so that the high tension terminal is inserted into the inner bore of the supporting boss. Alternatively, the supporting boss is designed so that the high tension terminal is disposed to fit the outer cylindrical surface of the supporting boss. The axial positions of the first and second shoulders in the high tension case are arbitrarily selected, as long as they are separately positioned.
Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiments described below with reference to the following drawings.
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patent: 5537983 (1996-07-01), Nakajima
patent: 5679012 (1997-10-01), Murata
patent: 5682865 (1997-11-01), Maekawa et al.
patent: 5827079 (1998-10-01), Murata
patent: 0 508 374 (1992-10-01), None
patent: 0 738 831 (1996-10-01), None
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patent: 10-303045 (1998-11-01), None
Adachi Norihiro
Osuka Kazutoyo
Denso Corporation
Nixon & Vanderhye PC
Vo Hieu T.
Yuen Henry C.
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