Internal-combustion engines – High tension ignition system – Having a specific ignition coil
Patent
1993-05-13
1994-08-02
Nelli, Raymond A.
Internal-combustion engines
High tension ignition system
Having a specific ignition coil
F02P 1100
Patent
active
053335929
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an ignition coil for ignition systems in combustion engines.
More particularly, it relates to an ignition coil with at least one secondary connection part.
Ignition coils having a sleeve-shaped secondary connection part which projects out of the housing of the ignition coil and conducts high voltage to the spark plug are known in general. These secondary connection parts have a connection dome and a spark plug terminal which is permanently coupled with the latter.
The location where the connection dome is coupled with the spark plug terminal is constructed in such a way that the spark plug terminal can be swiveled to a slight extent relative to the connection dome which rigidly projects from the housing of the ignition coil. This swiveling serves to compensate tolerances between the ignition coil which is fastened directly to the cylinder head and the spark plug which is fixed in a spark plug recess of the cylinder head of the internal combustion engine.
Since the spark plug recess, for purposes of mounting, has a greater inner diameter than the outer diameter of the spark plug or spark plug terminals connected with the ignition coil, it may happen in rare instances when mounting the ignition coil on the cylinder head that the spark plug terminal does not slide onto the spark plug, but instead enters the intermediate space between the wall of the spark plug recess and the spark plug. This faulty mounting is generally not detected during the initial operation of the internal combustion engine because, with the high voltage provided by the ignition coil, the improperly contacted spark plug receives a sufficient, though reduced, ignition voltage by sparkover or arcing.
However, the voltage which is transmitted in this way is not sufficient for generating an ignition spark at the defectively contacted spark plug under adverse operating conditions caused by weather and aging. This leads to misfiring and to emission of unburned fuel from the internal combustion engine, which must be prevented.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an ignition coil for ignition systems of internal combustion engines of motor vehicles, which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in an ignition coil for ignition systems for internal combustion engines, in which a centering sleeve is provided and formed so that it is adapted to the shape of a spark plug recess of the internal combustion engine and allows for a movement clearance, and the centering sleeve is undetachably fastened to the spark plug terminal.
When the ignition coil is designed in accordance with the present invention, it has the advantage over the prior art that the above-mentioned shortcomings are satisfactorily prevented. For this purpose, a centering sleeve is permanently fastened to the spark plug terminal of the ignition coil. With an ignition coil supplemented in this way, it is ensured that the spark plug terminal penetrates into the spark plug recess centrically relative to the spark plug even when incorrectly mounted and a proper operation of the internal combustion engine is ensured via a reliable contact of the spark plug with the ignition coil even under adverse operating conditions.
In accordance with another advantageous feature of the present invention, the spark plug has an elastic bush forming its outer boundary, at which at least one bead is constructed, particularly a torus which can be brought into a locking position when a centering sleeve is slid onto the spark plug terminal so as to hold the centering sleeve in a positive engagement.
The bush can be slid over the connection dome of the secondary connection part accompanied by a radial widening when the spark plug terminal is coupled to the pin of the connection dome, and in doing so the torus is radially widened and this widening f
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Benedikt Walter
Betz Dieter
Grewe Werner
Haist Gerhard
Nelli Raymond A.
Robert & Bosch GmbH
Striker Michael J.
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