JP3350063B2 - Misfire detection device for internal combustion engine and control device for internal combustion engine using this misfire detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a misfire detection device for an internal combustion engine and a control device for the internal combustion engine using the misfire detection device. More particularly, the present invention relates to a normal operation utilizing ion current generated during ignition combustion in a cylinder. A misfire detection device for an internal combustion engine which has a high ballast property and has high reliability of misfire detection, and a highly accurate internal combustion using the misfire detection device The present invention relates to an engine control device.

[0002]

2. Description of the Related Art A conventional misfire detecting apparatus utilizing ion current generated during ignition combustion is disclosed in JP-A-2-1049.
There is one disclosed in Japanese Patent Publication No. 78. This misfire detection device includes a circuit component for detecting an ion current generated near the ignition plug when a combustion state occurs in the cylinder due to spark generation at the ignition plug as an electric signal, and an ion output from the ion current detection circuit. A predetermined range is extracted from the current signal using a masking unit such as a filter circuit, and the ion current signal is compared and determined by a comparison unit having a reference level set as a determination reference, thereby determining the presence or absence of a misfire state. It is configured as follows. If such a misfire detection device is attached to the internal combustion engine, if a misfire condition occurs in any one of the cylinders of the internal combustion engine, this condition can be detected accurately and quickly, and the fuel injection control of the internal combustion engine can be performed. By suppressing or cutting the fuel supplied to the cylinder, the unburned fuel can be prevented from flowing into the exhaust gas purification device, and the exhaust gas purification device can be prevented from being deteriorated.

[0003]

In a conventional misfire detecting apparatus, an ion current signal generated during combustion is input to a circuit for detecting misfire, and whether or not a misfire state has occurred using a raw waveform of the ion current signal. Or have you detected. In order to determine whether normal combustion has occurred during ignition or whether a misfire has occurred in each cylinder of the internal combustion engine using the raw waveform of the ion current signal, a window is generated and an appropriate range is set. , And compares a preset threshold value with the amplitude value of the fetched ion current signal, and makes a determination based on the magnitude relationship between these values.
However, the waveform of the ion current signal fluctuates extremely greatly depending on the rotation speed of the internal combustion engine, the load of the load, and the like, and it is extremely difficult to determine at what point in time the ion current signal should be captured. Also, even if the threshold value for distinguishing between the normal combustion and the misfire state is appropriately set,
Since ignition noise frequently occurs in the ignition coil unit, if a large ignition noise occurs, it may exceed a threshold level set for misfire determination, and may cause erroneous determination.
In order to avoid such erroneous determination, it is essential to provide a filter circuit in the determination circuit section for masking the frequency region of ignition noise and removing unnecessary ignition noise. As a result, the signal processing process becomes complicated and the configuration of the signal processing circuit becomes complicated, so that the manufacturing cost increases. Further, the quality of the masking action determines the quality of the performance of the misfire detection device, which makes it difficult to manufacture a highly reliable device.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to detect a misfire in an internal combustion engine, which is configured to determine whether the combustion is normal or misfire by using an ion current signal generated at the time of ignition. Accordingly, an object of the present invention is to provide a misfire detection device for an internal combustion engine that can detect a misfire state stably and with high reliability without being affected by the operation state of the internal combustion engine and without causing erroneous determination. Another object of the present invention is to utilize the misfire detection device having high detection reliability in a fuel injection control system or the like, to suppress the supply of fuel to a cylinder in which a misfire state has been detected, SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device for an internal combustion engine that prevents the control device from being supplied to an exhaust gas purification device.

[0005]

To achieve the above object, the present invention provides an ion current detection circuit for detecting an ion current generated by combustion in a cylinder, and an ion current signal output from the ion current detection circuit. A misfire detection device for an internal combustion engine, comprising: a determination unit for determining whether an internal state of the cylinder at the time of ignition is normal combustion or a misfire state by utilizing the ion current signal output from the ion current detection circuit. Integrating means for capturing and integrating, and peak holding means for capturing one or both of a maximum peak value and a minimum peak value by capturing the ion current signal output from the ion current detection circuit,
The determination means uses both the integration signal output from the integration means and the peak data output from the peak hold means to determine whether the internal state of the cylinder is normal combustion or misfire. Make a decision. The present invention also provides an ion current detection circuit for detecting an ion current generated by combustion in a cylinder, and an internal state at the time of ignition of the cylinder which is normal combustion using an ion current signal output from the ion current detection circuit. A misfire detection device for an internal combustion engine, comprising: a judgment means for judging whether or not a misfire has occurred; an integration means for receiving and integrating the ion current signal output from the ion current detection circuit; and an output signal from the integration means. A peak hold means for receiving an integrated signal and holding one or both of a maximum peak value and a minimum peak value, and the determination means uses the peak data output from the peak hold means to determine the It is determined whether the internal state is a normal combustion or a misfire state. Further, the present invention provides an ion current detection circuit for detecting an ion current generated by combustion in a cylinder, and using the ion current signal output from the ion current detection circuit to determine that the internal state of the cylinder at the time of ignition is normal combustion. A misfire detection device for an internal combustion engine, comprising: a determination unit configured to determine whether or not a misfire condition is detected. The peak that captures the ion current signal output from the ion current detection circuit and holds both a maximum peak value and a minimum peak value. Hold means is provided, and the determination means determines whether the internal state of the cylinder is normal combustion or misfire using peak data output from the peak hold means, The peak hold means holds a maximum peak value and a minimum peak value and calculates an average value of these peak values, and the determination means Large peak value, minimum peak value, enter the average value, and performs the determination by a plurality of combinations of each value.
In addition, the present invention provides at least an ignition timing signal by inputting data relating to various operating states of the internal combustion engine and operating the arithmetic processing means for predetermined control prepared in the storage means using the data. And a fuel injection signal, and supplies the obtained ignition timing signal and the fuel injection signal to the respective control target parts to execute operation control of the internal combustion engine. When the misfire detection device determines that a predetermined cylinder is in a misfire state, the misfire detection device includes a control unit that adjusts the ignition timing signal for the cylinder and suppresses or cuts the fuel injection signal. .

[0006]

The integrator in the control apparatus for an internal combustion engine according to the present invention.
In the misfire detection device utilizing the above, it is possible to evaluate an ion current signal generated at the time of ignition not in terms of a mere instantaneous amplitude value in a raw waveform but in terms of area. For this reason, even if a large ignition noise occurs momentarily at the time of ignition, the integral value is small, so that it does not affect the determination of the presence or absence of misfire. Thus, the robustness can be increased. Also, when the internal combustion engine is in a low rotation state or in a light load state,
Although the ion current signal has a low output value, the judgment is made based on the integral value, so that a sufficient judgment signal can be obtained. Also book
Peak hold means in a control device for an internal combustion engine according to the invention
In the misfire detection device utilizing the characteristic value of the waveform amplitude value of the ion current signal is extracted and the presence or absence of a misfire is determined using the characteristic value, so that the combustion state of each cylinder of the internal combustion engine is determined. Even when the waveform is unstable and the ion current signal varies, it is possible to detect a sufficient difference between the normal combustion state and the misfire state. And, according to the present invention,
In the control unit of the fuel engine, the reliability of misfire detection is high
Since various controls are performed using the misfire detection device,
The degree improves. Also, a misfire condition occurs in any of the cylinders
The ignition timing of the cylinder at an appropriate timing.
To adjust or limit or cut fuel injection.
This causes unburned fuel to be supplied to the exhaust gas purifier.
Exhaust gas purification device
Of internal combustion engine operation in terms of exhaust gas
Improve the performance. In the misfire detection device in which the integrating means and the peak hold means are used in parallel or in series, the respective advantages described above can be combined, and a serial misfire detection configured to obtain peak data for an integrated signal. Since the detection device uses the highest waveform portion of the signal, the reliability and accuracy of detection are further improved .

[0007]

1 is a block diagram of a control apparatus for an internal combustion engine according to the present invention .
1 is an embodiment showing an electric circuit system of an ignition system of a multi-cylinder internal combustion engine including a misfire detection device. This embodiment shows an example of a one-plug one-coil type electronic wiring system (DIS) configured to have one ignition coil corresponding to an ignition plug for each cylinder. In this embodiment, the loss
The fire detection device has an integration type circuit configuration . Reference numeral 1 denotes a control unit serving as control means, and the control unit 1 is constituted by a microcomputer. The control unit 1 internally stores a storage element ROM for storing fixed data and a control program required for ignition timing control, fuel injection control, and the like, and various data which are taken in timely and used for various controls. It includes a storage element RAM for writing and reading as needed, a CPU for performing digital arithmetic processing of various data, and the like. Since such a configuration is well known, detailed description is omitted.

In order to control the ignition timing and the like of each of a plurality of cylinders, various data on the state and environment of the internal combustion engine are required. These data are respectively detected by the corresponding sensors and input to the control unit 1 in the form of analog signals or digital signals. The various data to be input include crank angle data from the crank angle sensor 2, air flow rate (Q _A ) from the air flow rate sensor 3, throttle angle (θ _TH ) from the throttle sensor 4, and output voltage (V _B ), water temperature data (T _W ) from the water temperature sensor 6 for measuring the temperature of the cooling water of the internal combustion engine, and the like. These data are input to the control unit 1, where they are processed according to a predetermined calculation formula, and an ignition timing signal "IGN" 7 for instructing an ignition timing suitable for the operating condition is output for each cylinder. . Ignition timing signal 7 output from control unit 1
Is amplified by the amplifier 8 to a predetermined level at which the power transistor 9 of the next stage can be driven, supplied to the power transistor 9, and made to conduct. When the power transistor 9 conducts, current from the battery (+ B) flows through the primary winding of the ignition coil 10. The conduction / interruption of the power transistor 9 is determined according to the waveform of the ignition timing signal 7 input to the base. When the turned-on power transistor 9 is cut off in accordance with the ignition timing signal 7, a high voltage corresponding to the cut-off current is induced on the secondary side of the ignition coil 10 and the spark for ignition is applied to the spark plug 11 of the first cylinder. Generate.

The ionic current detection circuit 12 includes the ignition coil 1
0 is provided between the low potential end of the secondary winding and ground. The ion current detection circuit 12 is a Zener diode 12
a, a capacitor 12b, a resistor 12c and a diode 12d connected in parallel with the resistor 12c. Spark plug 1
When a spark is generated at 0, electric charge is accumulated in the capacitor 12b at a voltage specified by the Zener diode 12a. Thereafter, the combustion heat ionizes the area near the ignition plug 11, so that a current path is formed, The electric charge accumulated in 12b flows as an ion current. This ion current is detected as a potential difference signal between both ends of the resistor 12c. The signal output from the ion current detection circuit 12 is output as an ion current signal “ION” 13.

The above-mentioned ion current signal 13 is input to an integration circuit 15 via a window generation circuit 14. The window generation circuit 14 uses the set window to input a characteristic waveform portion containing no noise from the ion current signal to the integration circuit 15. The integration circuit 15 integrates the input ion current signal, and then outputs the obtained integration signal to the control unit 1. The means for misfire determination provided inside the control unit 1 performs misfire determination using an integrated signal obtained by integrating the characteristic waveform portion of the ion current signal provided from the integration circuit 15. Any means can be used for the means for misfire determination and its process.

FIG. 2 shows signal waveforms of required parts of the ion current detection circuit 12, the window generation circuit 14, and the integration circuit 15. FIG. 2A shows a waveform of a main part of the ion current signal, which is a voltage signal “ION” 13 generated from the output terminal of the ion current detection circuit 12. In the waveform of the ion current signal 13, reference numeral 13a denotes ignition noise generated at the time of ignition,
A portion 13b is a characteristic waveform portion generated by the ion current. FIG. 2B shows a window signal for setting a window in the window generation circuit 14. The window signal 16 is generated to take the characteristic waveform portion 13 b of the ion current signal 13 into the integration circuit 15. FIG. 2C shows an integrated signal obtained by integrating the ion current signal 13 during a window period set by the window signal 16. This integration signal is output from the output terminal of the integration circuit 15. When a misfire condition occurs, the ion current signal is almost zero.
Therefore, when a misfire state occurs, the integrated signal also becomes almost zero.

The circuit configuration of the ignition device and the misfire detection device for the first cylinder described with reference to FIG.
The same applies to the nth to nth cylinders.

The integrated signal of the ion current signal for each cylinder input to the control unit 1 as described above is thereafter used for, for example, ignition timing control and fuel injection control. As described above, the control unit 1 is provided with control means for performing ignition timing control and fuel injection control. A fuel injection signal "INJ" 17 for each cylinder is generated by the fuel injection control. The fuel injection signal 17 is amplified by the amplifier 18 and the power transistor 1
9 to drive the injector 20 of the first cylinder. This circuit configuration is also provided for each cylinder.

When the control unit 1 determines that a misfire state has occurred in the first cylinder based on the integration signal given from the integration circuit 15, the ignition timing signal 7 is limited and the fuel injection signal 17 is cut or cut. Limited. Similar control is performed for each of the other cylinders.

The characteristic waveform portion of the ion current signal 13 output from the ion current detection circuit 12 is
If it is configured to integrate at 5 and determine whether or not there is a misfire state based on the obtained integrated signal, the characteristic portion 13b of the ion current signal 13 is evaluated in area, so that it is accurate. It is possible to detect a misfire state quickly and stably.

In the above embodiment, the ion current detection circuit 12
Is provided for each cylinder, but as another configuration, a misfire state is detected in the same manner as described above by providing an ion current detection circuit for each of two opposed cylinders or for each of more cylinders. It can also be configured.

Next, a description will be given of the window generation circuit 14 and the integration circuit 15 used in the misfire detection device, or software means for realizing functions equivalent thereto. 3 and 4 show circuit examples realized by a hardware configuration.
3 shows the integration circuit 15, and FIG. 4 shows the window generation circuit 14. The integrating circuit shown in FIG. 3 has a well-known circuit configuration using an operational amplifier 15a, and the window generating circuit 14 shown in FIG. 4 has two level signal generating circuits 14a and 14a.
b. Window generation circuit 14
Outputs two level signals 21 and 22 for generating a window (16 in FIG. 2B) for inputting a predetermined region (characteristic waveform portion), which is not limited to the ignition noise in the ion current signal, to the integration circuit 15. I do. When these level signals 21 and 22 and the ion current signal 13 are input to an AND circuit (not shown), the level signal 2
The window 16 is set by a combination of 1 and 22,
Ion current signal portion 1 in the area where the window is set
3b is extracted as an output signal of the AND circuit. Each level signal generation circuit 14a, 1 of the window generation circuit 14
4b is a signal for resetting the crank angle sensor 2b.
It is desirable to use the REF signal output from the. In this way, the characteristic waveform portion 13b of the ionic current signal extracted by the window generation circuit 14 is input to the input terminal 15b of the integration circuit 15, where integration processing is performed, and an integration signal is output from the output terminal 15c. You. Integration circuit 15
Although not shown, a circuit configuration for resetting the value integrated at a predetermined timing is added in practice.

As described above, if the presence or absence of a misfire state is determined based on the signal obtained by integrating the ion current signal, the value of the detection signal greatly differs between the normal combustion state and the misfire state. In addition, misfire determination can be easily and accurately performed.

FIG. 5 shows an embodiment in which the functions of the window generating circuit and the integrating circuit are realized by a software configuration. When the device is implemented with a software configuration, the window generation circuit 14 and the integration circuit 15 shown in FIG. 1 are not necessary as circuit elements. Therefore, in this case, the ion current detection circuit 1
The ion current signal “ION” 13 output from the control unit 2 is directly input to the control unit 1. The means for executing the flowchart shown in FIG. 5 is registered and prepared as a program inside the control unit 1.
In the flowchart shown in FIG.
In, it is determined whether or not the predetermined window is set. Generation of a window by a soft method is, for example,
This is performed by using a free-run counter using the REF signal and the POS signal from the crank angle sensor. If YES in step 31, A in step 32
Activate the / D conversion process to convert the characteristic waveform portion of the ion current signal from analog to digital. Step 33 is a step of determining whether or not the signal has been converted to a digital signal. In step 34, an integral operation is performed. If NO in step 31, step 3
Then, it is determined whether or not it is the first time that the outside of the window has been taken out and taken in (for example, whether the operation by this program is the first after the ignition switch is turned on, or the outside of the window after that). It is determined whether or not the first data acquisition has been performed.) When step 35 is YES, step 3
6. Execute 6 to reset the integrated value (to 0 or an appropriate initial value, or another appropriate value). If NO in step 35, step 37 is executed to hold the integral value. Even with the above-mentioned soft configuration, the same operation as the above-mentioned hardware configuration is produced.

Next, the control device for the internal combustion engine according to the present invention will be described .
The misfire detection device in the second embodiment will be described. Second
The misfire detection device in the embodiment has a circuit configuration of a peak hold system. That is, in the configuration of this embodiment,
In the embodiment of FIG. 1, a peak hold circuit is used instead of the integration circuit 15. Therefore, in the circuit of FIG. 1, a peak hold circuit is provided at a position where the integration circuit 15 is provided. Other configurations are the same as those shown in FIG. Hereinafter, only the configurationally different parts will be described. FIG. 6 shows an example of a circuit for realizing a peak hold circuit with a hardware configuration. This peak hold circuit is interposed between the window generation circuit 14 and the control unit 1, receives an ion current signal 13 output from the ion current detection circuit 12 via the window generation circuit 14, Has a function of detecting at least one of a low peak value (minimum value) and a high peak value (maximum value) in the characteristic waveform portion, and supplying these peak values to the control unit 1. Therefore,
The peak hold circuit is a low peak hold circuit 41
And the high peak hold circuit 42. The low peak hold circuit 41 includes an operational amplifier 41a
Is a well-known circuit configuration based on. Its input terminal 4
An ion current signal from the window generation circuit 14 is input to 1b. Since the ion current signal passes through the window generation circuit 14, the characteristic waveform portion of the ion current signal 17 is input. The voltage representing the low peak value is
The output terminal 41d is held by the capacitor 41c.
Output from When resetting the low peak hold circuit 41, the R output from the crank angle sensor 2
The reset switch 41e is turned on by the EF signal,
This is performed by discharging the electric charge of the capacitor 41c. On the other hand, the high peak hold circuit 42 also has a well-known circuit configuration based on an operational amplifier 42a, and its input terminal 42b is connected to the window generation circuit 14 similarly.
The ion current signal passed through is input. as a result,
The high peak value of the characteristic waveform portion of the ion current signal is held as a voltage in the capacitor 42c. Capacitor 42
The high peak value held as the inter-terminal voltage of c is
Output from the output terminal 42d. Also, the capacitor 42c
A reset switch 42e is connected in parallel to the high peak hold circuit 42 by turning on the reset switch 42e by the REF signal.

In the peak hold circuit, between the output terminal of the low peak hold circuit 41 and the output terminal of the high peak hold circuit 42, as shown by a broken line block 43, resistors 44 and 45 having a predetermined resistance value are provided. When the connection is made by using the intermediate point 46, the average value of the low peak value and the high peak value can be output from the intermediate point 46.

As described above, the low peak value, the high peak value of the characteristic waveform portion of the ion current signal and the average value thereof are appropriately detected by using the peak hold circuit, and these peak values are used alone or in combination. When the normal combustion or misfire state is determined, the misfire state can be determined clearly and easily, because the determination can be made based on the characteristic amplitude value of the ion current signal as compared with the method using the raw waveform of the ion current signal. be able to. Further, if the combustion state at the time of ignition in the cylinder is determined by using the average value of the low peak value and the high peak value, the combustion in the smoldering state can be detected, which is convenient for control. During smoldering, the reference zero voltage level itself shifts and the absolute value of the average value increases, so that it is possible to determine whether or not a smoldering state exists.

In the case of the peak hold method, FIG.
As shown in FIG. When the apparatus is realized by a software configuration, the window generation circuit 14 and the peak hold circuit are not necessary as circuit elements. Therefore, in this case, the ion current signal “ION” 13 output from the ion current detection circuit 12 is directly input to the control unit 1. The means for executing the flowchart shown in FIG. 7 is registered and prepared as a program in the control unit 1. According to the flowchart shown in FIG.
It is determined whether or not is within the predetermined window. If YES in step 51, steps 52 and 5
In step 3, the A / D conversion process is started and executed, and a predetermined portion of the ion current signal is converted into a digital signal. In step 54, the value (A / D) of the acquired data is compared with the low peak value (PL). If the value is smaller than the low peak value, the low peak value (PL) is calculated in step 55 using the data value (A / D). Update. Step 54
If the acquired data value is larger than the low peak value, the data value (A / D) is compared with the high peak value (PH) in step 56. If the data value is larger than the high peak value, in step 57, the high peak value (PH) is updated with the data value (A / D). Thus, the low peak value or high peak value of the ion current signal existing in the window is held. Step 51
If the answer is NO in step 58, the process proceeds to step 58, where it is determined whether or not it is the first time that the outside of the window has been taken in (for example, after the ignition switch is turned on, the operation by this program is started). First or
Alternatively, it is determined whether or not it is the first time that the data is taken out of the window and the data is taken in.) Step 5
If 8 is YES, step 59 is executed to reset the low peak value and the high peak value (to 0 or an appropriate initial value or another appropriate value). Step 5
If NO in step 8, step 60 is executed to hold the low peak value and the high peak value, respectively. In addition,
Although the steps for calculating the average value are not shown in the above flow chart, the steps for calculating the average value only need to be provided at the stage when the low peak value and the high peak value have been determined, so that the illustration is omitted. Even with the above-described software configuration, the same operation as the above-described hardware configuration is produced.

In the above-described first and second embodiments, the configurations using the integration circuit and the peak hold circuit independently have been described. However, these can be combined. For example, the integration circuit 15 and the peak hold circuit may be provided in parallel for each cylinder, and the output signals may be appropriately combined to determine the presence or absence of a misfire state. Further, an integration circuit 15 is provided after the window generation circuit 14, and a peak hold circuit is provided thereafter. The same peak data as in the case of the ion current signal is obtained for the integration signal. It can also be configured to detect the presence or absence of a misfire state by using this.

FIG. 8 is a flowchart showing a case where the ignition timing control and the fuel injection control are performed using the misfire detection signal obtained by the misfire detection device in the above embodiment .
A program for this control is provided in the control unit 1. Step 71 In the intake mass air flow Q, the engine speed N, the power supply voltage V _B, taken from the corresponding sensor, respectively described above, monitors them. Based on these data, in step 72, an ignition timing signal θ _base and a fuel injection width signal Ti _base which are the basis of control are calculated. In step 73, it is determined whether the combustion is normal or misfire is performed using the misfire detection signal obtained by the above-described misfire detection device according to the present invention. If NO in step 73, the ignition timing signal θ _base and the fuel injection width signal Ti _base obtained in step 74 are used as ignition timing and fuel injection control signals θ and Ti, respectively.
On the other hand, if YES in step 73, in step 75, the control signal θ for the ignition timing is set as θ _base −α, and the control signal Ti for fuel injection is set as Ti _base −β. As a result, the ignition timing signal θ is delayed by α, and the fuel injection signal Ti is reduced by the pulse width β. This limits the fuel. If necessary, β = Ti _base
In some cases, the fuel may be cut by setting Ti = 0. In step 76, the control content is displayed on the display. This gives the driver an accurate message about the misfire occurrence state, thereby improving reliability.

According to the above control, when a misfire state occurs in any of the plurality of cylinders, the combustion supply to the cylinder is reduced to prevent the unburned fuel from being sent to the exhaust gas purification device. Thus, the purification function of the exhaust gas purification device can be prevented from being deteriorated by the unburned fuel.

[0027]

As apparent from the above description, the present invention has the following effects. According to the misfire detection device using the integration circuit, since the ion current can be evaluated as an area for a predetermined period, it is possible to prevent instantaneously generated ignition noise from having a fatal effect on misfire determination, Robustness against ignition noise can be improved, and accurate and highly reliable misfire detection can be performed. Further, even when the internal combustion engine is in a low-speed and light-load state, a sufficient signal output value can be obtained by the integration effect.
According to the misfire detection device using the peak hold circuit,
By maintaining the maximum value or the minimum value of the ionic current for a predetermined period, or both, even when the combustion state of the internal combustion engine is unstable and the output waveform of the ionic current varies, the most characteristic portion of the output waveform And misfire detection can be performed accurately and stably. In particular, it is also possible to determine smoldering by obtaining an average value calculated from the maximum value and the minimum value and monitoring the average value. And the loss as above
The control device for an internal combustion engine of the present invention using a fire detection device
When a misfire condition occurs in any of the cylinders, the ignition timing of the cylinder is adjusted at an appropriate timing,
The fuel injection can be limited or cut, thereby preventing the unburned fuel from being supplied to the exhaust gas purification device, preventing the exhaust gas purification device from deteriorating, and improving the exhaust gas. The operation reliability of the internal combustion engine. Further, the integrating means and the peak hold means are connected in parallel.
Or in the case of a misfire detection device used in series
Each of the advantages described above can be combined,
Series configured to obtain peak data for
Misfire detection detection device uses the waveform part with the highest signal
Therefore, the reliability and accuracy of the detection become higher.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a control device for an internal combustion engine according to the present invention.

FIG. 2 is a waveform diagram showing signal waveforms of various parts of the circuit.

FIG. 3 is a circuit diagram illustrating an example of an integration circuit.

FIG. 4 is a circuit diagram illustrating an example of a window generation circuit.

FIG. 5 is a flowchart for realizing integration processing in software.

FIG. 6 shows a second embodiment of the control device for an internal combustion engine according to the present invention .
FIG. 3 is a circuit diagram illustrating an example of a peak hold circuit in FIG.

FIG. 7 is a flowchart for implementing a peak hold process in software.

FIG. 8 is a flowchart showing an ignition timing / fuel injection control process of the internal combustion engine using the misfire detection device and the misfire determination process.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control unit 10 ignition coil 11 ignition plug of first cylinder 12 ion current detection circuit 14 window generation circuit 15 integration circuit 20 injector 41 low peak hold circuit 42 high peak hold circuit

Continuation of front page (56) References JP-A-3-64645 (JP, A) JP-A-4-54283 (JP, A) JP-A-2-104978 (JP, A) JP-A-52-69689 (JP) JP-A-58-183845 (JP, A) JP-A-61-258955 (JP, A) JP-A-2-33447 (JP, A) JP-A-4-54255 (JP, A) 3-21541 (JP, U) JP-A-2-83344 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02P 1/00-17/12 F02D 41/00-41 / 40 F02D 43/00-45/00

Claims (4)

(57) [Claims] An ion current detection circuit for detecting an ion current generated by combustion in a cylinder, and an ion current signal output from the ion current detection circuit is used to determine whether the internal state of the cylinder at the time of ignition is normal combustion. Or a misfire detection device for an internal combustion engine, comprising: a determination unit that determines whether a misfire has occurred. An integration unit that captures and integrates the ion current signal output from the ion current detection circuit, and an output from the ion current detection circuit. Peak holding means for receiving both the maximum peak value and the minimum peak value by taking in the ion current signal to be provided, wherein the determination means includes an integration signal output from the integration means and an output signal from the peak holding means. It is determined whether the internal condition of the cylinder is normal combustion or misfire condition by using both of the peak data. A misfire detection device for an internal combustion engine, characterized in that: 2. An ion current detection circuit for detecting an ion current generated by combustion in a cylinder, and an ion current signal output from the ion current detection circuit is used to determine whether the internal state of the cylinder at the time of ignition is normal combustion. Or a misfire detection device for an internal combustion engine, comprising: a judgment means for judging a misfire state. An integration means for taking in the ion current signal output from the ion current detection circuit for integration processing, and an output from the integration means. A peak hold unit that captures an integrated signal and holds one or both of a maximum peak value and a minimum peak value is provided, and the determination unit uses the peak data output from the peak hold unit to determine the cylinder of the cylinder. A misfire detection device for an internal combustion engine, wherein it is determined whether the internal state is normal combustion or a misfire state. . 3. An ion current detection circuit for detecting an ion current generated by combustion in a cylinder, and using an ion current signal output from the ion current detection circuit to determine whether the internal state of the cylinder at the time of ignition is normal combustion. Or a misfire detection device for an internal combustion engine, comprising: a determination unit for determining whether a misfire has occurred. A peak hold that captures the ion current signal output from the ion current detection circuit and holds both a maximum peak value and a minimum peak value. Means, wherein the determination means comprises:
Using the peak data output from the peak hold means to determine whether the internal state of the cylinder is normal combustion or misfire state, the peak hold means, the maximum peak value and the minimum Holding the peak values and calculating the average of these peak values,
The misfire detection device for an internal combustion engine, wherein the determination means inputs a maximum peak value, a minimum peak value, and an average value, and performs the determination based on a combination of a plurality of values. 4. Inputting data relating to various operating states of the internal combustion engine, operating the arithmetic processing means for predetermined control prepared in advance in the storage means using the data and at least outputting an ignition timing signal and calculated fuel injection signal, the control apparatus for an internal combustion engine by supplying the ignition timing signal obtained with the fuel injection signal to each of the control target unit executes operation control of the internal combustion engine, according to claim 1 to 3
The misfire detection device according to any one of the above,
When the misfire detection device determines that a predetermined cylinder is in a misfire state, the internal combustion engine further comprises control means for adjusting the ignition timing signal for the cylinder and suppressing or cutting off the fuel injection signal. Engine control device.