JPH04262070A - Combustion detecting device for internal combustion engine - Google Patents

Abstract

PURPOSE:To surely detect a misfire by detecting negative ions and free electrons in a cylinder generated by combustion, shifting the level to the positive side for comparison with the reference value, and filtering it to remove the noise generated when an engine is fitted to an actual vehicle. CONSTITUTION:Voltage is applied to the ignition plug 4 of each cylinder of an internal combustion engine, the ion current generated by combustion is detected by a current detecting diode 5 and the like, and the ion current detection signal is outputted. The ion current detection signal is compared with the preset reference value by a comparator 7 for wave-form shaping. Only the signal with the width of the preset period or above among the wave-form- shaped signals is passed by a low-pass filter 10.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion detection device for an internal combustion engine, and more particularly to a combustion detection device for an internal combustion engine that can prevent malfunctions caused by noise.

0002

2. Description of the Related Art FIG. 3 is a block diagram showing a conventional combustion detection device for an internal combustion engine. In the figure, 1 is a power transistor that is turned on and off by an ignition signal, 2 is an ignition coil connected to the primary side of the power transistor 1, 3 is a power distributor connected to the secondary side of the ignition coil, and 4 is a power distributor. 3, a plurality of spark plugs each connected to the spark plug 4; 5 a plurality of ion current detection diodes each connected to the spark plug 4;
6 is an ion current detection device for detecting an ion current; 7 is a comparator provided in the ion current detection device 6 to compare the ion current detection signal with a reference value; and 8 is an output terminal.

Next, the operation of the conventional combustion detection device for an internal combustion engine shown in FIG. 3 will be explained with reference to FIG. 4. Now, when the ignition signal S1 as shown in FIG. A high voltage signal S2 as shown in FIG. 4(b) is generated. This high voltage signal S2 is supplied to the spark plug 4 of each cylinder via the power distributor 3, and ignites it. When the mixed gas in the cylinder burns due to this ignition, an ion current is generated, and positive ions of this ion current are detected as an ion current detection signal S3 as shown in FIG. 4(c) through the diode 5, and compared. The ion current detection output signal S4 is supplied to the device 7 and compared with a reference value, and an ion current detection output signal S4 as shown in FIG. 4(d) is obtained at the output terminal 8. When this ion current detection output signal S4 is at a high level, it is determined that there is combustion, and when it is at a low level, it is determined that there is a misfire.

0004

[Problem to be Solved by the Invention] Since the conventional combustion detection device for an internal combustion engine is configured as described above, when installed in an actual vehicle, various noises are superimposed on the signal S4, so even though a misfire occurs. Signal S4 is “H” due to noise
There was a problem in that there was a risk that a signal would be output and the combustion would be determined to have occurred normally. This invention was made to solve the above problems.
An object of the present invention is to obtain a combustion detection device for an internal combustion engine that can remove various noises generated when installed in an actual vehicle and can reliably detect misfires.

[0005]

[Means for Solving the Problems] A combustion detection device for an internal combustion engine according to the present invention applies voltage to a spark plug in a cylinder of an internal combustion engine, detects an ion current due to combustion, and outputs an ion current detection signal. The method comprises an ion current detection means, a waveform shaping means for shaping the waveform of the ion current detection signal using a predetermined comparison voltage, and a filter means for passing only a signal having a width of a predetermined time or more among the signals after waveform shaping. It is something that

[0006]

[Operation] In this invention, a negative ion current due to combustion is detected, the negative ion current detection signal is shifted by a predetermined bias voltage, and the shifted negative ion current detection signal is transferred to the bias voltage. It is compared with a first reference value shifted by a predetermined amount, and after filtering, is further compared with a second reference value to obtain an ion current detection output signal.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of the present invention,
1 to 5, 7, and 8 are the same as described above. 6A is an ion current detection device. In this embodiment, 2 of the ignition coils 2
One end (positive end) of the next side is connected to the power distributor 5, and the other end (negative end) is connected to the ion current detection device 6A. The ionic current detection diode 5 is incorporated into the power distributor 3. Further, a positive polarity battery is used for the ion current detection battery section in the ion current detection device 6A. That is, in this embodiment, anions and free electrons are detected in the ionic current. The ion current detection device 6A includes a bias circuit 9 provided on the input side to shift the detected ion current detection signal by a predetermined bias voltage, and a bias circuit 9 provided on the output side of the bias circuit 9 to shift the detected ion current detection signal by a predetermined bias voltage. A comparator 7 that compares the voltage with a first reference value shifted by a predetermined amount from the bias voltage, a low-pass filter 10 provided on the output side of the comparator 7 and filtering the output, and a low-pass filter 10 provided on the output side of the low-pass filter 10 that filters the output of the comparator 7. It has a comparator 11 that compares the output with a second reference value, and an inversion circuit 12 that is provided on the output side of the comparator 11 and inverts the output.

Next, the operation of the embodiment of the present invention shown in FIG. 1 will be explained with reference to FIG. Now, when an ignition signal is applied to the base of the power transistor 1, the power transistor 1 is turned on, and when the power transistor 1 is turned off, a high voltage signal is generated on the secondary side of the ignition coil 2. This high voltage signal is supplied to the spark plug 4 of each cylinder via the power distributor 3 to ignite it. When the mixed gas in the cylinder burns due to this ignition, an ionic current is generated, and anions and free electrons of this ionic current are detected as an ionic current detection signal S1 as shown in FIG. 2(a) through a diode 5. be done. This ion electric detection signal S1 is shifted by a predetermined bias voltage in the bias circuit 9 and becomes a signal S2 as shown in FIG. 2(b).
The signal is supplied to the comparator 7 and compared with a first reference value, and a signal S3 as shown in FIG. 2(c) is obtained at its output side. This signal S3 is passed through a low-pass filter 10 and shown in FIG.
), the signal S4 is further supplied to the comparator 11 and compared with the second reference value, and the output side of the signal S4 is as shown in FIG.
) is obtained. This signal S5 is inverted by the inverting circuit 12, and as a result, the signal S5 is output to the output terminal 8 as shown in FIG.
) is obtained as the ion current detection output signal S6. When this ion current detection output signal S6 is at a high level, it is determined that there is combustion, and when it is at a low level, it is determined that there is a misfire. The signal S6 obtained in this way is “
Since it outputs a "H" level signal and, in the event of a misfire, a "L" level signal, it becomes unnecessary to distinguish between noise from the final output waveform of the ion current detection device and the ion current detection signal, ensuring misfire detection. Be able to do it.

[0009]

As described above, according to the present invention, there is provided an ion current detection means for applying a voltage to a spark plug of a cylinder of an internal combustion engine, detecting an ion current due to combustion, and outputting the ion current detection signal; Since it is equipped with a waveform shaping means that shapes the waveform of the ion current detection signal using a predetermined comparison voltage, and a filter means that passes only a signal having a width of a predetermined time or more among the signals after waveform shaping, it is possible to This has the effect of providing a combustion detection device for an internal combustion engine that can remove various generated noises and reliably detect misfires.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining the operation of FIG. 1;

FIG. 3 is a configuration diagram showing a conventional combustion detection device for an internal combustion engine.

FIG. 4 is a waveform diagram for explaining the operation of FIG. 3;

[Explanation of symbols]

4 Spark plug 5 Ion current detection diode 6A Ion current detection device 7, 11 Comparator 9 Bias circuit 10 Low pass filter 12 Inversion circuit

Claims (1)

[Claims] 1. An ion current detection means for applying a voltage to a spark plug of a cylinder of an internal combustion engine, detecting an ion current due to combustion, and outputting an ion current detection signal; What is claimed is: 1. A combustion detection device for an internal combustion engine, comprising: a waveform shaping means for shaping a waveform, and a filter means for passing only a signal having a width longer than a predetermined time among the signals after waveform shaping.