JPS5828429B2 - The examination room of the 100m2 meter heater - Google Patents

Description

Description: The present invention relates to a misfire detection device for an ignition circuit of an internal combustion engine, for example, an automobile internal combustion engine.

Conventionally, the most common means for detecting misfire in an internal combustion engine of an automobile or the like is to observe waveforms using an oscilloscope.

However, in the conventional method of detecting misfire by visually monitoring the ignition waveform displayed on an oscilloscope, when there are many cylinders or during acceleration, the waveform changes,
This became so fast that it became difficult to grasp the exact state of the waveform, and so detection of misfire required great skill.

The present invention has been made in consideration of the above-mentioned points and has as its gist the provision of a misfire detection device for an internal combustion engine ignition circuit which comprises means for extracting an ignition signal from a high tension cord which is connected to an ignition circuit of an internal combustion engine, means for detecting a misfire state by comparing the ignition signal obtained by this means with a preset reference signal, means for detecting an ignition cylinder in the ignition circuit, and means for obtaining a cylinder-by-cylinder misfire signal from the ignition cylinder signal obtained by this means and the misfire signal obtained by the misfire detection means. It is an object of the present invention to provide a misfire detection device for an internal combustion engine ignition circuit which can reliably detect misfire in each cylinder without requiring any particular skill even when there are a large number of cylinders or during acceleration, and which can also estimate the location of a fault.

An embodiment of the present invention will now be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes an ignition circuit of an internal combustion engine, for example an automobile, 2 denotes an integration circuit, 3 denotes a comparison and judgment circuit, and 4 denotes a synchronization circuit.

The ignition circuit 1 is for a four-cylinder engine, and includes a battery, a DC power supply 11, an ignition coil 12 connected to the DC power supply 11, a parallel circuit of a point 13 and a capacitor 14 connected to the DC power supply 11 via a first winding 12a of the ignition coil 12 and opening and closing when each cylinder is ignited, and an intention cord 15 connected to the secondary winding 12b of the ignition coil 12.
The distributor 16 is connected to the internal combustion engine via a plug cord 17a to 17d, and switches its contacts in sequence in response to the operation of the internal combustion engine. Spark plugs 18a to 18d for each cylinder are connected to the distributor 16 via plug cords 17a to 17d.

The high tension cord 15 of the ignition circuit 11
A signal obtained by clamping the signal by a clamp 21 is applied to an integrating circuit 2 consisting of a resistor 22 and a capacitor 23, and the integrated output is applied to the comparison and judgment circuit 3.

The comparison and judgment circuit 3 includes an inverting amplifier circuit 31a which inverts and amplifies the signal applied from the integration circuit 2, an inverting amplifier circuit 31b which further inverts and amplifies the output of the amplifier circuit 31a,
The inverting amplifier circuit 31a.

maximum value storage circuits 32a and 32b for storing the maximum value of the signal output from the
a reset circuit 33 for resetting the maximum value storage circuits 32a, 32b when the point 13 is closed; a phenomenon B voltage comparison circuit 35a and a phenomenon A voltage comparison circuit 35b for comparing the contents stored in the maximum value storage circuits 32a, 32b with reference values E1, E2 applied to input terminals 34a, 34b from a storage device (not shown);
and a misfire determining circuit 36 which determines the output of the voltage comparator circuits 35a, 35b at the time when the point 13 is opened to detect a misfire state.

The output of the comparison and judgment circuit 3, the forward misfire judgment circuit 36
The misfire determination signal outputted from is sent to a synchronization circuit 4.

The synchronization circuit 4 includes a point opening/closing detection circuit 41 which detects the opening/closing of the points 13 by taking out a signal from, for example, a common connection terminal of the ignition coil 12 and a terminal 19 connected to the repo wire 13. An ignition signal of the ignition plug 18a is detected by a sensor 20 which is made of, for example, a highly permeable annular magnetic body with a coil wound thereon and which is attached to, for example, the plug cord 17a for the first cylinder out of the plug cords 17a to 17d.
A shaping circuit 42 shapes the waveform of this detection signal, an output of this shaping circuit 42 is input to a load terminal 43a to set the number of cylinders, an output of the point opening/closing detection circuit 41 is input to a count terminal 43b to perform a countdown operation of a preset counter 44, and a BOD code output from output terminals 45a to 45d of this preset counter 44 is output from
The circuit comprises a cylinder number discrimination circuit 46 which converts the signal into a zero-based signal and outputs it, a cylinder-by-cylinder misfire signal detection circuit 47 which detects a misfire signal for each cylinder based on the outputs of the discrimination circuit 46 and the misfire determination circuit 36, and output terminals 48a-48d which output the outputs of the detection circuit 47 for each cylinder.

In addition, the preset counter 44 is provided with BOD preset terminals 49a to 49d.

The BOD preset terminals 49a to 49d are used to preset the number of cylinders and are weighted as [1"n2An-'4"'-"8"]. Any numerical value can be preset by previously writing "1" or "0" to each of the terminals 49a to 49d.

FIG. 1 shows a case where the number of cylinders is set to 4, and the button and terminal 49a.

A "0" signal is given to terminals 49b and 49d, and a "1" signal is given to terminal 49c, making [0100] the preset signal.

This preset signal is set in the counter 44 when a signal is applied to the load terminal 43a, and the count terminal 43
Each time a signal is given to b, the count is decreased by one.

Next, the present invention configured as described above will be described in detail.

When the intention code 15 is clamped by an alligator clip 21, an ignition signal having a waveform as shown in FIG. 2a is usually obtained.

When this signal is fed to the integrating circuit 2 and integrated, if ignition is normal, a signal having a waveform as shown in FIG.

If the signal shown in FIG. 2c is taken as the standard waveform, in the case of misfire, the signal shown in FIG. 2a' and a' will be generated by the clock clip 21.
The signal shown in FIG. 1 enters the integrating circuit 2, and the output signal is
The result is a signal as shown in Figures b' and b''.

There are two types of misfire: Phenomenon A, which is caused by an excessive plug gap or a broken wire in the cord, and Phenomenon B, which is caused by an insufficient plug gap or a defective point. In the case of Phenomenon A, the following phenomenon is observed:
As shown in Figures 2a" and 2b", phenomenon B has the characteristic that the voltage of the reflected wave component and the positive component is very high compared to the standard waveform, and as shown in Figures 2a" and 2b", phenomenon C has the characteristic that the absolute value of the capacitive discharge voltage component and the negative voltage is very low.

Therefore, the firing order of each cylinder of a four-cylinder internal combustion engine is usually 1
, 3, 4, 2, but if the fourth cylinder is experiencing phenomenon A and the third cylinder is experiencing phenomenon B, the signal waveforms on each circuit are shown in FIG. 3, and will be explained below with reference to FIGS. 2 and 3.

The signal (1) output from the integrating circuit 2 is sent to the comparing and judging circuit 3, and is then inverted and amplified by the inverting and amplifying circuit 31a to become signal (2), and is then sent to the maximum value storing circuit 32a, where the maximum value of the signal is stored.

That is, the maximum voltage absolute value on the negative side for the output signal (3) of the integrating circuit 2 is stored in the memory circuit 32a.

Furthermore, the output (III) of the inverting amplifier circuit 31a is further inverted and amplified by an inverting amplifier circuit 31b, becomes a signal (IV) and is sent to a maximum value memory circuit 32b.

This memory circuit 32b stores the maximum positive voltage value for the output signal (3) of the integrating circuit.

The maximum value storage circuits 32a, 32b are reset by the output (3) of the switch opening/closing detection circuit 41 every time the switch 13 is closed.

On the other hand, the voltage value to be stored in the memory circuits 32a and 32b occurs at the same time that the point 13 opens.
3 opens and closes the memory circuit 32a.

The maximum voltage value is repeatedly stored in and reset to 32b.

Thus, the signal II output from the maximum value memory circuit 32a is sent to a phenomenon B voltage comparator circuit 35a and compared with a reference value E1 applied to an input terminal 34a from, for example, a computer storage device.

This reference value E1 is a value obtained in advance through an experiment.
This is the criterion for determining misfire.

The comparison circuit 35a utilizes the characteristic of phenomenon B, namely, that the absolute value of the negative voltage is very low compared to the standard waveform as explained with reference to Figs. 2a" and 2b", to compare the signal I output from the memory circuit 32a with the reference value E1 to detect the state of phenomenon B.

On the other hand, the signal II output from the maximum value memory circuit 32b is sent to a phenomenon A voltage comparator circuit 35b and compared with a reference value E2 applied to an input terminal 34b from the memory device.

The comparison circuit 35b is a characteristic of the phenomenon A, i.e.,
As explained in connection with ' and 'b', the state of phenomenon A is detected by comparing the signal 1 output from the memory circuit 32b with the reference value E2, utilizing the characteristic that the voltage of the positive component is very high compared to the standard waveform.

The output signal II of the phenomenon B voltage comparison circuit 35a and the phenomenon A
The output signal (III) of the voltage comparator circuit 35b is coupled to the signal output from the point switch detection circuit 41 and the misfire determination circuit 3
6, and while the point 13 is open, it is judged whether the signal output from the comparison circuits 35a, 35b is a misfire signal or not.

The misfire signal output from the misfire determination circuit 36 is sent to a cylinder-by-cylinder misfire signal detection circuit 47 .

On the other hand, when the sensor 20 detects an ignition signal of the first cylinder,
This detection signal [present] is applied as a signal II through the shaping circuit 42 to the load terminal 43a of the preset counter 44, and signals previously given through the preset terminals 498 to 49d are set in the counter 44.

In this embodiment, the value "4" is preset in the counter 44.

The content of this counter 44 counts down by one each time the point open detection signal is output from the point open/close detection circuit 41.

When the content of the counter 44 reaches 10", the counter 44 is set to "4" again by a signal O applied to the load terminal 43a.

The contents of the counter 44 are outputted to output terminals 45a to 45d as signals indicated by @@@@ in the BOD:I-do format, and are converted into decimal numbers by a cylinder number discrimination circuit 46.

The discrimination circuit 46 outputs a signal to one of the output terminals according to the content of the counter 44, and to a terminal corresponding to the cylinder number.
1" signal to indicate the cylinder number that is igniting at that time.

The output (s) of the cylinder number discrimination circuit 46 is sent to a cylinder-by-cylinder misfire signal detection circuit 47 together with the output (s) of the misfire determination circuit 36, and the detection circuit 47 outputs the cylinder-by-cylinder misfire signals to output terminals 48a to 48d.

In this embodiment, a misfire signal is output to the signal input 9 for the third cylinder and the signal input 9 for the fourth cylinder.

That is, since the third cylinder is experiencing the misfire phenomenon of phenomenon B, the signal waveform has a very low negative voltage absolute value compared to the standard waveform, and is detected by the phenomenon B voltage comparison circuit 35a.

On the other hand, since the fourth cylinder is experiencing the misfire phenomenon A, the signal waveform has a very high positive component voltage compared to the standard waveform, and is detected by the phenomenon A voltage comparison circuit 35b.

The output signal II of the phenomenon B voltage comparison circuit 35b and the phenomenon A
The output signal of the voltage comparator circuit 35b is
6 to judge the state of misfire, and a misfire signal based on the result of the judgment is sent to a cylinder-by-cylinder misfire signal detection circuit 47.

The cylinder misfire signal detection circuit 47 detects the misfire signal for each cylinder based on the misfire signal and the signal from the cylinder number discrimination circuit 46, and outputs a third cylinder misfire signal O and a fourth cylinder misfire signal O.

With this configuration, misfires in all cylinders can be detected by detecting the signal from the high tension cord 15, and misfire signals for each cylinder can be obtained from the output terminals 48a to 48d.

Therefore, for example, if misfire signals are concentrated in a specific cylinder, the corresponding spark plug or plug wire is defective. If misfire signals are indiscriminately output to all cylinders, the points 13, high tension wire 15,
It is found that there is a defect in the ignition coil 12, etc.

Although the above embodiment has been described with respect to a four-cylinder engine, it is apparent that the present invention can be similarly applied to internal combustion engines with any number of cylinders.

As described above, according to the present invention, there is provided a misfire detection device for an internal combustion engine ignition circuit, comprising: means for extracting an ignition signal from an intention code in the ignition circuit of an internal combustion engine; means for detecting a misfire state by comparing the ignition signal obtained by this means with a preset reference signal; means for detecting ignition cylinders in the ignition circuit; and means for obtaining cylinder-specific misfire signals from the ignition cylinder signal obtained by this means and the misfire signal obtained by the misfire detection means. Therefore, it is possible to provide a misfire detection device for an internal combustion engine ignition circuit that can reliably detect misfires on an individual cylinder basis without requiring any particular skill, even when there are a large number of cylinders or during acceleration, and that can also estimate the location of a defect.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an operational waveform diagram for explaining the operation of the embodiment, and FIG. 3 is a timing chart for explaining the operation of the embodiment. 1. Ignition circuit, 2. Integration circuit, 3.
...Comparison and judgment circuit, 4...Synchronization circuit, 1
2: Ignition coil, 13:
Point, 15... - High tension cord,
16: Distributor, 18a to 18d
...Spark plug.

Claims (1)

[Claims] 1. A misfire detection device for an internal combustion engine ignition circuit, comprising: means for extracting an ignition signal from a high tension cord leading to the ignition circuit of an internal combustion engine; means for detecting a misfire state by comparing the ignition signal obtained by this means with a preset reference signal; means for detecting an ignition cylinder in said ignition circuit; and means for obtaining a cylinder-specific misfire signal from the ignition cylinder signal obtained by this means and the misfire signal obtained by the misfire detection means.