JPH05256241A - Ignition plug for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide an internal combustion engine ignition plug which can miniaturize an ignition device. CONSTITUTION:An ignition plug has a pair of piezoelectric elements 11, 12 which are set in series in a casing 18 with their end faces abutting each other, and an input terminal 14 connected to an external power source and a GND terminal 15 connected to an earth side are connected to the piezoelectric element 11 on one side, and an output terminal 20 having a central pole 20A being opposite through a fixed clearance to an external pole 18A which is formed in the casing 18 and connected to the earth side and the GND terminal 15 connected to the earth side are connected to the piezoelectric element 12 on the other side. Thus, since the ignition plug can dispense with an usual large- sized ignition coil, an ignition device can be sharply miniaturized, and moreover high voltage is generated through a pair of piezoelectric elements 11,12 internally set in an ignition plug, whose structure can therefore be sharply simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a spark plug used for ignition of an internal combustion engine.

[0002]

2. Description of the Related Art FIG. 3 shows an ignition coil for supplying a high voltage to an ignition plug for an internal combustion engine. A secondary coil 2 is wound on a cylindrical core 1 via a bobbin 5, and the secondary coil 2 A primary coil 4 is wound on the upper part of the bobbin 3 via a bobbin 3. Then, a low-voltage direct current is passed through the primary coil 4,
This primary current is suddenly cut off by an interrupter (not shown) to generate a high voltage in the secondary coil 2 by the electromagnetic induction action.
This is supplied to an ignition plug (not shown) to generate discharge fireworks.

A device having the same structure as such an ignition coil is described, for example, in Japanese Patent Laid-Open No. Sho 60.
There is a publication of -501961.

[0004]

In the conventional ignition plug ignition device as described above, the ignition plug and the ignition coil are separate bodies, and the ignition coil occupies a large volume in the ignition device of the internal combustion engine. Become.

However, with the recent trend toward miniaturization of engines, there is a possibility that the conventional ignition device becomes too large to be mounted on the engine.

The present invention has been made to solve the drawbacks of the conventional ignition device for an internal combustion engine.
That is, it is an object of the present invention to provide an ignition plug for an internal combustion engine that can reduce the size of the ignition device.

[0007]

In order to achieve the above object, the present invention has a pair of piezoelectric elements that are internally mounted in series in a casing with their end faces abutting each other. Is connected to an input terminal connected to an external power source and a GND terminal connected to the ground side, and is opposed to an outer electrode formed on the casing of the other piezoelectric element and connected to the ground side through a predetermined gap. It is characterized in that an output terminal having a center pole and a GND terminal connected to the ground side are connected.

[0008]

The ignition plug for an internal combustion engine is inserted into the engine body and fixed, and the power source is connected to the input terminal.

When the input terminal is energized, an electric field formed between the input terminal and the GND terminal causes instantaneous crystal distortion in the input side piezoelectric element, and a shock is applied to the output side piezoelectric element. ..

The piezoelectric element on the output side generates a high voltage due to the impact from the piezoelectric element on the input side, and discharges sparks from the center pole of the output terminal toward the outer pole of the casing, causing sparks to enter the combustion chamber of the engine. Fly.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail based on the embodiments shown in the drawings.

In FIG. 1, reference numerals 11 and 12 denote piezoelectric elements, and the pair of piezoelectric elements 11 and 12 are fitted and pushed in the insulator 13 in a serial state. One of the piezoelectric elements 11 is an element on the input side, and an input terminal (+ terminal) 14 is attached to one side of the side surface as shown in FIG. The GND terminal (-terminal) 15 is attached to the opposite position, the input terminal 14 is connected to the outer terminal 16, and the GND terminal 1
5 is grounded via a copper washer 17, a plug casing 18 and an engine body 19 which are provided so as to come into contact with the flange portion 15a of the GND terminal 15.

The other piezoelectric element 12 is an element on the output side, the upper end surface of which is in contact with the lower end surface of the piezoelectric element 11 on the input side, and the output terminal (+ terminal) 2 is provided on one of the side surfaces.
0 is attached to the output terminal 20, and a center pole 20A is formed at the lower end portion of the output terminal 20 so as to project downward. The lower end surface of the output terminal 20 and the outer pole 18A are formed by bending the lower end portion of the plug casing 18. They are facing each other through the gap. And
A part of the GND terminal 15 described above is attached to the side surface of the piezoelectric element 12 at a position facing the output terminal 20 in the radial direction.

The ignition plug is inserted into the engine body 19 and fixed by a screw portion 18B formed on the outer peripheral portion of the plug casing 18, and the battery 22 is connected to the outer terminal 16 via the distributor 21.

When the outer terminal 16 is energized, the electric field formed between the input terminal 14 and the GND terminal 15 causes instantaneous crystal strain in the piezoelectric element 11 on the input side, and the piezoelectric element 12 on the output side. A shock is applied to.

The piezoelectric element 12 on the output side generates a high voltage by the impact from the piezoelectric element 11 on the input side, and discharges from the center pole 20A of the output terminal 20 toward the outer pole 18A of the plug casing 18. Sparks are blown into the combustion chamber of the engine.

[0017]

As described above, according to the present invention, since it is not necessary to use a large ignition coil as in the prior art, the ignition device can be significantly downsized and a high voltage can be generated in the ignition plug. Since it is performed by a pair of piezoelectric elements installed inside,
The structure can be very simple.

[0018]

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention,

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a side sectional view showing a conventional example.

[Explanation of symbols]

 11, 12 ... Piezoelectric element 14 ... Input terminal 15 ... GND terminal 18 ... Plug casing 18A ... Outer pole 19 ... Engine body 20 ... Output terminal 20A ... Center pole

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication H01L 41/113 H01T 13/40 8021-5G

Claims (1)

[Claims] 1. A casing has a pair of piezoelectric elements that are internally mounted in series with their end faces abutting each other, and one piezoelectric element is connected to an input terminal connected to an external power source and to the ground side. An output terminal having a central pole opposed to an outer pole formed on the casing of the other piezoelectric element and connected to the ground side with a predetermined gap, and a GND terminal connected to the ground side. A spark plug for an internal combustion engine, which is connected.