Inductor devices – With outer casing or housing – Potted type
Patent
1984-05-17
1986-04-01
Kozma, Thomas J.
Inductor devices
With outer casing or housing
Potted type
29606, 26427219, 336198, 336205, 336225, H01F 2702, H01F 2730
Patent
active
045801223
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
The invention relates generally to an ignition coil for ignition systems of internal combustion engines and more particularly to a coil with an insulating gap between the primary and secondary windings. In ignition coils of this kind, the insulating distance between the secondary winding carrying the high voltage and areas of the ignition coil having a lower potential is proportionate to the highest voltage between two potentials; this is known to be in the area of the high voltage output of the secondary winding.
Because the secondary winding is coaxial with the hollow-cylindrical primary winding, the insulating distance must necessarily exist over the entire length of the secondary winding, and in the vicinity of the first chamber of the secondary winding this distance is oversized, so that a larger quantity of potting resin is required, and the weight of the ignition coil is increased unnecessarily.
THE INVENTION
With the ignition coil for ignition systems of internal combustion engines according to the invention, the size and weight of the ignition coil are reduced, while its output remains the same. Briefly, the invention is to provide that the insulating distance of the individual chambers of the secondary winding be only so large as to correspond to the existing voltage between the chamber potential and the lower potential of the adjacent area of the ignition coil.
Advantageous further features of the invention are provided. With the embodiment of the ignition coil including a tapered coil winding form the application of the invention to a preferred embodiment of an ignition coil is illustrated. The embodiment of the ignition coil with a geometrically decreasing winding height provides the stepped change between two adjacent chambers that is most favorable in terms of the insulating distance. With the embodiment of the ignition coil including struts of trapezoidal cross-section, a secure position of the individual windings in the chamber and favorable resistance of the struts to bending are attained.
The area of the insertion or assembly opening, which is formed by the end face of the coil body of the primary winding and the bottom of the housing, must be absolutely tight while the ignition coil is potted--which is done without the iron core. In order to attain this tightness, it is already known to mold a sheath onto the end face of the coil body and to the housing bottom and to join these parts with an interference fit.
It is also known to dispose respective integral lids, outwardly offstanding, on the end face of the coil body and on the housing bottom, next to join both lids with a press fit and then to cut off these lids at a distance from the housing bottom. It is further known to have an inwardly pointing sheath protrude from the housing bottom, thereby spacing the iron core apart from the coil body. All of these previously known sealing means are expensive in terms of manufacturing processes.
With the further development of the ignition coil with removable lid segments, the required tightness in the vicinity of the insertion opening is attained at low engineering expense. Because the potting of the ignition coil is effected before the two lids are removed, both predetermined breaking points provide the required sealing, and only after the potting compound has cooled are both bottoms cut off and the iron core inserted.
DRAWINGS
FIG. 1 shows an axial section of an ignition coil for ignition systems of internal combustion engines; and
FIG. 2 is a fragmentary and partially sectional view of the coil housing bottom after the potting of the ignition coil.
DESCRIPTION OF THE EXEMPLARY EMBODIMENT
In an ignition system for internal combustion engines, FIG. 1 shows shows an ignition coil with a laminated iron core 10, which is disposed coaxially with the axis 11 of the ignition coil, and a coil body 12 coaxial with the iron core 10 and having a primary winding 13. Also coaxial therewith is a coil body 14 in chambered form and having a secondary winding 15.
A cup-shaped, substantia
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patent: 3236937 (1966-02-01), Harkness et al.
patent: 4084144 (1978-04-01), Weniger
patent: 4179796 (1979-12-01), Allen
patent: 4403403 (1983-09-01), Hosoya et al.
Kozma Thomas J.
Robert & Bosch GmbH
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