JPH04148067A - Ignition plug for internal combustion engine - Google Patents

Abstract

PURPOSE:To make it unnecessary to use a high pressure proof diode, to realize a low cost, and to detect the signal of ion current easily, by providing at least one electrode provided to pass through a penetration hole passing the side of an insulator, and to detect the ion current generated by the combustion. CONSTITUTION:This ignition plug furnishes a central electrode 1 to generate a kindling source of combustion by discharging, an earth electrode 2 provided opposing to the central electrode 1, an insulator 3 to cover the central electrode 1, and a housing 4 to cover a part of the insulator 3. In this case, an electrode 20 for ion current detection is assembled in the ignition plug, and its one end is projected in a cylinder of the internal combustion engine. And the other end of the electrode 20 is connected to the connection of a resistor 9 and a capacitor 11 through a lead line 21. This ion current detecting electrode 20 is provided passing through a penetration hole 23 which passes the side of the insulator 3, at the opposite side of the central electrode 1 to the earth electrode 2. And the ion current generated when the mixture gas is burnt by the ignition of the ignition plug is detected by the electrode 20, and picked up as the detecting signal from a output terminal 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spark plug for an internal combustion engine, and more particularly to a spark plug for an internal combustion engine that incorporates an ionic current detection electrode.

[Prior Art] Fig. 3 is a block diagram showing a conventional spark plug for an internal combustion engine. In Fig. 1, (1) is a center electrode that generates a spark for combustion by electric discharge, and (2) is this center electrode (1). A ground electrode provided opposite to the center electrode (3) is an insulator that covers the center electrode (1),
(4) is a housing that partially covers this insulator (3), and a ground electrode (2) is attached to this housing (4). (5) is a conductive terminal attached to one end of the center electrode (1);
5) is connected to the secondary side of the ignition coil (7) via a backflow prevention diode (6), and is also connected to the DC power source (10) via an ion current detection diode (8) and a resistor (9).
) is connected to the negative electrode of

Further, the cathode side of the ion current detection diode (8) is grounded via a capacitor (11) and a resistor (12). Then, the output terminal (13) is taken out from the connection point between the capacitor (11> and the resistor (12)).The secondary side of the ignition coil (7) is connected to the power transistor (15).
, its emitter is grounded, and its base is connected to an input terminal (1
6).

Next, the operation of the conventional spark plug for an internal combustion engine shown in FIG. 3 will be explained. When the power transistor (15) is controlled and turned off by the fuel injection timing/ignition timing control unit in synchronization with the rotation of the internal combustion engine, a back electromotive force is generated on the primary side of the ignition coil (7), and in response 2
A negative high voltage is generated on the next side, and this negative high voltage is supplied to the center pole (1) through the diode (6), and the center is connected between the pole (1) and the ground electrode (2). A discharge occurs, which ignites the spark plug. When the air-fuel mixture in the cylinder of the internal combustion engine (not shown) burns due to the ignition of this spark plug,
An ionic current is generated, and this ionic current flows through the diode (8
) is detected at the output terminal (13).

[Problem to be solved by the invention] The conventional internal combustion engine opening spark plug is configured as described above,
High-voltage diodes (6) and (8) are used to separate the path for the ion current detection signal and the high voltage path for ignition, making them expensive. Since the routes share the same cable (14) and have a common impedance, there is a problem in that noise at the time of ignition overlaps, making it difficult to detect the ionic current signal.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a spark plug for an internal combustion engine that is inexpensive and in which the detection of ion current is not affected by noise during ignition.

[Means for Solving the Problems] A spark plug for an internal combustion engine according to the present invention includes a center electrode that is provided so as to pass through a first through hole passing through the center of the insulator, and that generates combustion sparks by electric discharge; Attached to a housing that covers part of the center above! The insulator is equipped with a ground electrode facing the pole, and at least one electrode that is provided through a second through hole passing through the side of the insulator to detect the flow of ions produced by combustion.

[Function] In the present invention, at least one electrode for detecting the ionic current generated by combustion is incorporated into the spark plug, and the ionic current detection signal path is separated from the ignition high voltage path, and the electrode for detecting the ionic current is incorporated. is taken out to the outside through a second through hole passing through the side of the insulator.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram showing one embodiment of the present invention, and FIG.
), (9) to (13), (15), and (16) are the same as those described above. so that it protrudes into the cylinder. Then connect the other end of the electrode (20) to the resistor (
9) and the connection point of the capacitor (11). Further, an ion current detection electrode (2o) is provided on the same side of the ground electrode (2) as the center electrode (1). In addition, the central electric line 1t (
1) is provided through the first through hole (22) passing through the center of the insulator (3), while the ionic current detection electrode (2
o) is provided through a second through hole (23) through the side of the insulator (3).

Next, the operation of the embodiment of the present invention shown in FIG. 1 will be explained. Fuel injection timing is synchronized with the rotation of the internal combustion engine.
When the power transistor (15) is controlled and turned off by the ignition timing control unit, the ignition coil (7)
A back electromotive force is generated on the primary side of the
), a discharge occurs between the center electrode (1) and the ground electrode (2), which ignites the spark plug. When the air-fuel mixture in the cylinder of the internal combustion engine (not shown) burns due to the ignition of the spark plug, an ionic current is generated, which is detected by the electrode (20) and output as a detection signal to the output terminal (13). be done.

Here, in order to take out the ion current detection electrode (2o) to the outside, the second through hole (23) is opened in the side of the insulator (3), and the structure is simple, just by passing the electrode through it, so it is inexpensive. be.

In the above embodiment, one ion current detection electrode is provided, but a plurality of ion current detection electrodes may be provided, and in the above embodiment, the ion current detection electrode is placed on the same side of the ground electrode as the center electrode. Although this is the case where it is provided on the opposite side, it can be similarly applied when it is provided on the opposite side.

[Effect of the invention] As described above, according to this invention, the first
a center electrode that is provided to pass through the through hole of the insulator and generate a combustion spark through discharge; a ground electrode that is attached to a housing that covers a part of the insulator and faces the center electrode; and a ground electrode that passes through the side of the insulator At least one of the first through-holes is provided to pass through the second through-hole and detect an ionic current generated by combustion.
Since the ion current detection signal path and the ignition high voltage path are separated, it is not affected by noise during ignition. Therefore, it is possible to obtain a spark plug for an internal combustion engine in which the signal detection of the ion current is facilitated, and the ion current detection electrode can be connected to the outside at a low cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing essential parts of the present invention, and FIG. 3 is a block diagram showing a conventional spark plug for an internal combustion engine. In the figure, (1) is the center electrode, (2) is the ground electrode, (
3) is an insulator, (4) is a housing, (20) is an ion current detection electrode, (22) is a first through hole, and (23) is a second through hole. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] Provided to pass through a first through hole passing through the center of the insulator,
a center electrode that generates combustion sparks by electric discharge; a ground electrode that is attached to a housing that covers a part of the insulator and faces the center electrode; and a second through hole that passes through a side of the insulator. 1. A spark plug for an internal combustion engine, comprising at least one electrode for detecting an ionic current generated by combustion.