JPH04191467A - Ion current detecting device - Google Patents

Abstract

PURPOSE:To detect the ion current of multiple cylinders with the simple structure by applying the positive bias current to multiple ignition plugs through diodes, and generating the ion current with the movement of electron to obtain a large ion current quantity. CONSTITUTION:At the ignition time of an internal combustion engine, high voltage for ignition is generated in a secondary coil 9b, and the discharge current is flowed to a passage showed with an arrow, and discharge is generated between electrodes of an ignition plug 4 to ignite the air-fuel mixture for burning. At this stage, the ionization work is generated with combustion of the air-fuel mixture to generate the ion, and the ion current is flowed by the movement of electron, which is caused by the positive bias voltage of a power source 10, but since mass of the electron is remarkably small and the moving speed thereof is fast in comparison with the positive ion, ion current quantity becomes large. The voltage generated in an output terminal 9 by the generation of this ion current is detected to confirm the combustion of the air-fuel mixture. The bias voltage is applied through multiple diodes to detect the ion current of multiple cylinders with one ion current detecting device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion current detection device used, for example, in misfire detection in an internal combustion engine.

[Conventional technology]

A conventionally known device of this kind will be explained with reference to FIG. In the figure, 1 is the primary winding 1a and the secondary winding l
2 is a power transistor connected to the primary winding 1a to intermittent the primary current; 3 is a center electrode 3a connected to the negative polarity side of the secondary winding 1b; Peripheral electrodes 3 facing each other through a gap
4 is a spark plug connected to each of the peripheral electrodes 3b; 5 is a power source which is a bias means for applying a negative polarity bias voltage to a predetermined spark plug 4;
A resistor 7 is connected in series with the power source 5 and converts the ion current into a voltage, and 7 is an output terminal for detecting the voltage generated in the resistor 6. Together with the resistor 6, the resistor 7 constitutes an ion current detecting means. 8 is a diode that blocks reverse current.

In the device configured as described above, when the power transistor 2 is turned off at the ignition timing of the internal combustion engine, and the primary current of the secondary winding 1a is cut off, a high voltage for ignition is generated in the secondary winding 1b. It is applied to the center electrode 3a. Center electrode 3a
The high voltage for ignition applied to the spark plug 4 is propagated to the opposing peripheral electrode 3b through the gap, and further generates a discharge between the electrodes of the spark plug 4, thereby igniting and burning the air-fuel mixture.

At this time, ionization occurs as the mixture burns, and ions are generated. Here, the electrode of the spark plug 4 acts as an electrode for detecting ion current after the above-mentioned discharge, and an ion current flows due to the movement of positive ions due to the negative polarity bias of the power source 5. Combustion of the air-fuel mixture can be confirmed by detecting the voltage generated at the output terminal 7 due to the generation of this ion current.

[Invention or problem to be solved]

Conventional ion current detection devices are configured to generate ion current with negative polarity bias, so the amount of ion current is determined by the amount of movement of cations, or because cations have a large mass and a slow movement speed. However, the amount of ion current was also very small, which caused the problem of low detectability.

This invention was made to solve the above-mentioned problems, and an object thereof is to obtain an ion current detection device that can obtain a large amount of ion current and has excellent detectability.

[Means to solve the problem]

The ion current detection device according to the present invention is provided with bias means for applying a positive polarity noise voltage to the spark plug.

[Effect]

The bias means in this invention applies a positive bias voltage to the ignition plaque to generate an ion current by the movement of electrons.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In the figure, 9 is a primary winding 9a and a secondary winding 9
The positive polarity side of the secondary winding 9b is connected to the center electrode 3a. 10 is a predetermined spark plug 4
11 is a resistor connected in series with the power supply lO and converts the ionic current into voltage; 12 detects the voltage generated in the resistor 11; This is an output terminal for
1 constitutes an ion current detection means. 13 is a diode that blocks reverse current.

In the structure as described above, a high voltage for ignition (approximately 10 to 25 K) is applied to the secondary winding 9b at the ignition timing of the internal combustion engine.
V), a discharge current flows along the path shown by the arrow in FIG. 2(a), and a discharge is generated between the electrodes of the ignition plug 4 to ignite and burn the air-fuel mixture.

At this time, as in the conventional device, ionization occurs as the air-fuel mixture burns, and ions are generated. Here, due to the movement of electrons due to the positive polarity bias (approximately 300 V) of the power supply 10,
The ion current flows along the path shown by the arrow in Figure 2(b).The mass of electrons is significantly smaller than that of positive ions, and the moving speed is faster, so the amount of ion current is large (approximately 10 to
50 times).

Combustion of the air-fuel mixture can be confirmed by detecting the voltage generated at the output terminal 12 due to the generation of this ion current.

Furthermore, since the bias voltage is applied via a plurality of diodes 13, the ion currents of a plurality of cylinders can be detected by one ion current detection means, and the structure becomes simple.

In the above embodiment, the ion current detection means has a configuration in which voltage conversion is performed using a resistor, but it goes without saying that other configurations may be used.

Furthermore, although the above-mentioned embodiment shows a high-voltage power distribution system using a power distributor, it goes without saying that a low-voltage power distribution system that does not use a power distributor may be used.

Furthermore, in the above embodiment, the power source 10 is not described in detail, and does not include any means such as means for boosting the battery voltage with a DC-DC converter, means for using the primary voltage (or secondary voltage) of the ignition coil, etc. There may be a means.

〔Effect of the invention〕

As described above, according to the present invention, a positive bias voltage is applied to a plurality of spark plugs via diodes,
To obtain an ion current detection device that can obtain a large amount of ion current, improve detectability, and detect ion currents of multiple cylinders with a simple configuration because the ion current is generated by the movement of electrons. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG.
) is a circuit diagram showing the discharge path of the embodiment in FIG. 1, and FIG.
) is a circuit diagram showing the ion current path of the embodiment in FIG.
The figure is a circuit diagram showing a conventional device. In the figure, 9 is an ignition coil, 4 is a spark plug, 10 is a power source, 11 is a resistor, 12 is an output terminal, and 13 is a diode. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] An ignition coil that generates high voltage for ignition of an internal combustion engine, a plurality of spark plugs that are connected to the positive polarity side of this ignition coil and ignite the air-fuel mixture of each of the plurality of cylinders, and each of the plurality of spark plugs has a high voltage side connected to the high voltage side. a plurality of diodes whose cathodes are connected and each anode electrically connected to one point; bias means connected to the anodes of the plurality of diodes and applying a positive bias voltage to each of the spark plugs; and a detection means for detecting an ion current flowing due to the positive bias voltage of the bias means and ions generated during combustion of the air-fuel mixture.