Ignition Coil Device for Internal Combustion Engine

This invention relates to improvements in an ignition coil device for the spark ignitor of an internal combustion engine.

A prior-art device of the specified type has been as shown in FIGS. 1 and 2. Referring to the figures, numeral 1 designates a coil assembly in which a primary coil and a secondary coil are wound in a manner to be insulated from each other and are covered with a molding material. A core 2 forms a magnetic path which is common to the primary coil and the secondary coil wound in the coil assembly 1. Numeral 3 indicates a terminal which is connected to one end of the primary coil, numeral 4 a terminal which is connected to the other end of the primary coil and one end of the secondary coil in common, and numeral 5 a high-voltage terminal which is connected to the other end of the secondary coil. The terminal 3, the terminal 4 and the high-voltage terminal 5 are respectively fastened integrally with the coil assembly 1 by a molding material.

FIG. 3 shows an equivalent circuit of the prior-art device. Here, symbol 1a denotes the primary coil, and symbol 1b the secondary coil. In addition, FIG. 4 is an electric circuit diagram showing the state of connection during the use of the prior-art device. Referring to FIG. 4, a battery 6 supplies current to the primary coil 1a of the ignition coil. An interrupter 7 interrupts the current through the primary coil 1a according to the ignition timing of the engine. An ignition plug 8 sparks upon receiving a high voltage which is generated across the secondary coil 1b of the ignition coil.

In operation, when the interrupter 7 interrupts the current flowing through the primary coil 1a at a predetermined time after the conduction thereof therethrough, the high voltage is induced in the secondary coil 1b and is supplied to the ignition plug 8 through the high-voltage terminal 5.

The prior-art ignition coil device is constructed and operated as described above. Therefore, when it is combined with another device such as a distributor having a rotary shaft, a housing for supporting the shaft, etc., it must be arranged so as to avoid the rotary shaft, the housing, etc. This has led to the disadvantage that the whole structure is not balanced and that space is wasted.

According to this invention, an ignition coil device for an internal combustion engine having a primary coil, a secondary coil and a core for forming a magnetic path common to the coils is characterized in that the core and a coil assembly covering the coils are formed with coaxial holes so as to permit another member to penetrate through the inner parts of the respective coils and the core in a direction orthogonal to the main magnetic fluxes of the coils, thereby to facilitate the combination of the ignition coil device with another device having a rotary shaft, a housing for supporting the rotary shaft, etc. and to reduce the size of the whole structure.

FIGS. 1 and 2 are a plan view and a sectional side view showing a prior-art ignition coil device, respectively;

FIG. 3 is an equivalent electric circuit diagram of a general ignition coil;

FIG. 4 is an electric circuit diagram of a general ignition device for an internal combustion engine; and

FIGS. 5 and 6 are plan view and a sectional side view showing an ignition coil device according to an embodiment of the present invention, respectively.

In the drawings, the same symbols indicate the same or corresponding parts.

An embodiment of this invention will be described with reference to FIGS. 5 and 6. FIGS. 5 and 6 show one embodiment of the present invention. Referring to the figures, numeral 11 designates a coil assembly in which a primary coil 1a and a secondary coil 1b wound in a manner to be insulated from each other are covered with a molding material having an insulating property, such as polypropylene. The coil assembly 11 comprises coils 1a and 1b and a coupling portion 15, the coils 1a and 1b being covered by molding material which has an insulating property and which also forms the coupling portion, the molding material portions 13, 14 and 15 comprising one integral piece, namely, the coil assembly 11. The coils are wound in a manner to be respectively arranged on the right and left sides of the coil assembly, the middle part of which is formed with the coil aperture 11a through which a member to be inserted, not shown, such as the rotary shaft of a distributor can penetrate is located between the right and left coils 13,14. A core 21 forms a magnetic path which is common to the primary coil 1a and secondary coil 1b wound in the coil assembly 11, illustrated in FIG. 5 as a four-sided ring, defining the core aperture 21c by its inside surface, so constructed that the member to be inserted can penetrate through core aperture 21c, which is preferably coaxial with the coil aperture 11a. The core 21 comprises two U-shaped core members each of which includes a leg portion 21a, and connecting portions 21b, which protrude from both the ends of the leg portion 21a in the same direction. The two core members are coupled by butting the corresponding connecting portions to each other. Numeral 31 designates a terminal which is connected to one end of the primary coil 1a, numeral 41 a terminal which is connected to the other end of the primary coil 1a and one end of the secondary coil 1b in common, and numeral 51 a high-voltage terminal which is connected to the other end of the secondary coil 1b. The terminal 31, the terminal 41 and the high-voltage terminal 51 are fastened integrally to the coil assembly 11 by a molding material. Shown at numeral 10 is a resin coil bobbin for insulation of said coils from said core.

Changes in magnetic fluxes caused by the interruption of current through the primary coil 1a induces a high voltage in the secondary coil 1b in the core 21. In the present invention, besides the above function as the ignition coil, the ignition coil device has the function that the member to be inserted such as the rotary shaft of the distributor can penetrate inside the coils in a direction perpendicular to the main magnetic fluxes of the coils.

While, in the embodiment, the core 21 has been illustrated as being split into the plurality of parts, it may have any shape adapted to form a magnetic path, for example, an annular shape. In addition, while the coil aperture 11a formed in the coil assembly 11 has been illustrated as a square, it may well be in any other shape (for example, a circular shape).

As set forth above, according to this invention, an ignition coil device is so constructed that a member to be inserted can penetrate inside an ignition coil. Therefore, the combination of the ignition coil device with another device is facilitated, and the whole structure can be balanced and reduced in size.