JPH0914118A - Ignition coil for engine - Google Patents

Abstract

PURPOSE: To easily and accurately arrange an ignition voltage sensing capacitor by forming the capacitor while opposing a part of a primary coil bobbin projection from one end thereof to a high voltage electrode with a specified spacing as the capacitor. CONSTITUTION: A coil unit 5 to which a primary coil bobbin 4 is fitted is installed inside a hollow shaft of a secondary coil bobbin 2 from an open surface 7 of a coil case 6. Insulative resin such as epoxy resin is charged into the case 6 for integral molding. In this case, a coaxially projected cylindrical part 21 is integrated with one end of the secondary coil bobbin 2, while a ring plate-like high voltage electrode 9 is arranged on an outer periphery of the cylindrical part 21. A plate-like sensor electrode 10 is sandwiched between the primary coil bobbin 4 and an installing boss 8. A plate part 101 projected outward from one end of the primary coil bobbin 4 is opposed to the high voltage electrode 9 with a specified spacing to form a capacitor 28 for sensing ignition voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine ignition coil having a function of detecting an ignition voltage state when the engine misfires.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
A coil unit 63 in which the primary coil 1 and the secondary coil 62 are wound.
Mounted in the coil case 64, and the coil case 6
In an ignition coil of a potting type engine in which an insulative resin 65 is injected into 4 to be integrally molded, a ring-shaped sensor conductor is provided around a secondary side socket terminal 66 into which an ignition plug cord is inserted. By mounting 67, a capacitor for detecting an ignition voltage is formed between them, and it is possible to detect whether or not the spark discharge is normally performed by the spark plug depending on the voltage state induced in the capacitor. (Japanese Patent Application Laid-Open No. 5-306
669).

[0003]

The problem to be solved is that when a capacitor for detecting the ignition voltage is provided inside the ignition coil, it is provided at a high voltage portion, so that the capacitor has a dielectric breakdown. This means that it is necessary to ensure a sufficient distance between the electrodes so that the above phenomenon does not occur.

Further, when the capacitor is formed inside the ignition coil, it is easy to install the electrode at a predetermined position in the coil case, and it is not affected by the resin injection.
The question is whether the distance between the electrodes can be maintained with high accuracy.

[0005]

According to the present invention, when a capacitor for detecting an ignition voltage is installed inside an ignition coil of a potting type engine, each electrode forming the capacitor is easily and accurately positioned. In order to ensure that the secondary coil bobbin is formed with a cylindrical portion that is coaxially projected at one end, the plate-shaped high-voltage electrode is wound around the outer periphery of the cylindrical portion, and is formed to project inside the coil case side. A plate-shaped sensor electrode is sandwiched between the mounting boss of the primary coil bobbin and the primary coil bobbin, and the part protruding outward from one end of the primary coil bobbin faces the high-voltage electrode at a predetermined interval to form a capacitor. I am trying to do it.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The ignition coil of the engine according to the present invention is shown in FIG.
As shown in FIG. 3, a coil unit 5 in which a primary coil bobbin 4 wound with a primary coil 3 is coaxially fitted in a hollow shaft of a secondary coil bobbin 2 wound with a secondary coil 1, The coil case 6 is inserted from the open surface 7 into the coil case 6 and mounted therein, and an insulative resin such as epoxy is injected into the coil case 6 for integral molding.

At the center of the inside of the coil case 6, a boss 8 into which a core (not shown) is fitted is formed so as to project from the outside of the coil case 6 toward the open surface 7.
The boss 8 is inserted into the hollow shaft of the primary coil bobbin 4, and the coil unit 5 is inserted into the coil case 6.
Are positioned and mounted.

According to the present invention, in the engine ignition coil constructed as described above, the cylindrical portion 21 that is coaxially projected is integrally formed at one end of the secondary coil bobbin 2, and the outside of the cylindrical portion 21 is formed. A ring-plate-shaped high-voltage electrode (high-voltage plate) 9 is fitted around and mounted, and a plate-shaped sensor electrode (sensor plate) 10 is sandwiched between the primary coil bobbin 4 and the mounting boss 8. A plate portion 101 protruding outward from one end of the primary coil bobbin 4.
Is opposed to the high-voltage plate 9 with a predetermined gap, and a capacitor 28 for detecting an ignition voltage is formed.

The capacitor 28 for detecting the ignition voltage is
It may be formed over the entire circumference of the tubular portion 21, or may be formed in a part of the tubular portion 21.

A bent portion 10 is provided at the rear end of the sensor plate 10.
2 is formed, and when the primary coil bobbin 4 is fitted into the hollow shaft of the secondary coil bobbin 2 together with the sensor plate 10, the bent portion 102 is engaged with the flange portion of the primary coil bobbin 4 for positioning. It is like this.

A lead portion 91 is integrally formed on the high-voltage plate 9, and the coil unit 5 and the coil case 6 are formed.
When mounted inside, the groove formed at the tip of the lead portion 91 meshes with the head portion 131 of the secondary output pin 13 projecting into the coil case 6 for electrical connection. .

A terminal holder 14 is provided on the collar portion of the primary coil bobbin 4, and a sensor-side lead member 15, a primary-side lead member 16 and a secondary-side lead member 17 are attached to the holder 14, respectively. There is.

The lead member 15 is connected to one end of the sensor plate 10, and the groove formed at the tip of the lead member 15 has a coil case 6 for the sensor output terminal 18.
An electric connection is made by meshing with a head 181 which is provided so as to project inward.

The primary side lead member 16 has a primary coil 3
Winding start 31 is connected and the lead member 1
A groove formed at the tip of 6 meshes with a head portion 191 projecting in the coil case 6 of the primary terminal 19 for electrical connection.

The primary side coil member 3 is attached to the secondary side lead member 17.
End of the secondary coil 1 and the winding start 11 of the secondary coil 1 are connected, and a groove formed at the tip of the lead member 17 is provided so as to project into the coil case 6 of the secondary terminal 20. It is adapted to be meshed with 201 to be electrically connected.

A reverse current blocking diode 24 is attached to the collar portion 23 on the opposite side of the secondary coil bobbin 2, and its anode side is connected to the winding end 12 of the secondary coil 1 via a connection terminal 25. The cathode side is connected to the lead portion 91 of the high voltage plate 9.

In the ignition coil of the engine according to the present invention configured as described above, the high pressure plate 9 is mounted on the tubular portion 21 on the secondary coil bobbin 2 side, and the sensor is provided in the hollow shaft of the secondary coil bobbin 2. By simply fitting the primary coil bobbin 4 together with the plate 10, the high voltage plate 9 and the sensor plate 10 are opposed to each other with a predetermined gap therebetween to form the capacitor 28 for detecting the ignition voltage.

Therefore, according to the present invention, the capacitor 28 for detecting the ignition voltage can be easily installed in the coil case 6, and the high voltage plate 9 and the sensor plate 10 are fixed at predetermined positions. Since it is installed in a static manner, it does not move due to resin injection, and the interval can be maintained accurately.

Further, according to the present invention, the distance between the high-voltage plate 9 and the sensor plate 10 can be made sufficiently wide without causing any insulation damage without causing any dielectric breakdown.

At this time, as shown in FIG. 4, an insulating plate 29 is provided in order to increase the insulation distance between the tips of the high-voltage plate 9 and the sensor plate 10 so as to make the insulation breakdown more effective. It may be attached.

FIG. 5 shows an ignition circuit system of an engine using the ignition coil 33 configured as described above. The ignition circuit system includes a capacitor for detecting an ignition voltage, which is composed of a high voltage plate 9 and a sensor plate 10. An ignition detection circuit 35 is provided for detecting whether the spark plug 34 is in a normal spark discharge state or in a misfire state by extracting a sensor output voltage induced in the sensor 28 and comparing it with a reference voltage. In the figure, 36 is a battery power source, and 37 is an igniter for generating an ignition signal.

With such a structure, when the engine is ignited, there is a difference in the induced voltage of the capacitor 28 for detecting the ignition voltage between when the spark plug 34 normally discharges the spark and when it misfires. The sensor output voltage corresponding to the difference is level-detected in the ignition detection circuit 35, and it is detected whether the engine is ignited normally or in the misfire state.

Further, at the time of misfire, the diode 38 blocks a current in the direction opposite to the discharge current caused by the residual charge between the electrodes of the spark plug 34, and the capacitor 28
The detection voltage induced by
The misfire state of the engine is reliably detected.

[0024]

As described above, in the ignition coil of the engine according to the present invention, the coil unit is mounted in the coil case and the insulating resin is injected into the case to be integrally molded. A coaxially protruding cylinder is formed at one end, a plate-shaped high-voltage electrode is wound around the outer circumference of the cylinder, and a primary coil bobbin mounting boss and primary are formed inside the coil case to project. A plate-shaped sensor electrode was sandwiched between the coil bobbin and the part projecting outward from one end of the primary coil bobbin faced the high voltage electrode at a predetermined interval to form a capacitor for ignition voltage detection. In this way, it is possible to install the capacitor in the ignition coil easily and with good positional accuracy, and at a sufficient distance that does not cause dielectric breakdown of the capacitor. It has the advantage that it can be installed with.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an embodiment of an ignition coil of an engine according to the present invention.

FIG. 2 is a side sectional view of the ignition coil of the engine as seen from the right side in the embodiment.

FIG. 3 is a side sectional view of the ignition coil of the engine according to the embodiment as viewed from the left side.

FIG. 4 is a front sectional view showing another embodiment of the present invention.

FIG. 5 is an electric circuit diagram showing an ignition system of an engine using an ignition coil according to the present invention.

FIG. 6 is a partially sectional front view showing an ignition coil of a conventional engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Secondary coil 2 Secondary coil bobbin 3 Primary coil 4 Primary coil bobbin 5 Coil unit 6 Coil case 8 Primary coil bobbin mounting boss 9 High-voltage electrode (high-voltage plate) 10 Sensor electrode (sensor plate) 28 Ignition voltage detection capacitor

Claims (1)

[Claims] 1. A capacitor for ignition voltage detection comprising a high voltage electrode connected to an output end of a secondary coil and a sensor electrode facing the high voltage electrode is built in, and a primary coil bobbin is fitted inside a hollow shaft of the secondary coil bobbin. In the ignition coil of the engine, in which the coil unit is mounted in the coil case and the insulating resin is injected into the coil case to integrally mold the cylinder unit, the cylindrical portion is coaxially projected at one end of the secondary coil bobbin. And a plate-shaped high-voltage electrode is wound around the outer periphery of the cylindrical portion, and a plate-shaped sensor electrode is provided between the primary coil bobbin mounting boss and the primary coil bobbin mounting protrusion formed inside the coil case side. The capacitor is formed so that the part of the primary coil bobbin that protrudes outward from one end of the primary coil bobbin faces the high voltage electrode at a predetermined interval. Ignition coil of engine characterized by