JP2008051031A - Ignition device for internal combustion engine, and misfire detection method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition device and a misfire detection method, having high detection accuracy of combustion/misfire determination, even when a waveform of corona noise or residual noise after the completion of discharge are superimposed on a detection signal of an ionic current. <P>SOLUTION: Comparison between Tbd/Cca and Pd is performed. The possibility of combustion is determined when the expression of (Tbd/Cca) > Pd is satisfied, and a misfire state is determined when the expression of (Tbd/Cca) < Pd is satisfied. Then, a threshold number Nn exceeding an upper limit deviation threshold value Vsu is counted. When the expression of Nn > Nnc is satisfied, the misfire state is determined, and when the expression of Nn < Nnc is satisfied, the possibility of combustion is determined. A continuous number Nc of times continuously exceeding a lower limit deviation threshold value Vsl is counted. The misfire state is determined when the expression of Nc < Ncd is satisfied, and a combustion status is determined when the expression of Nc > Ncd is satisfied. Therefore, a combustion determination signal or a misfire determination signal depending on each determination status is generated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ignition device for an internal combustion engine and a misfire detection method using such an ignition device for an internal combustion engine.

  Research on the detection of the combustion / misfire state of a combustion chamber in an internal combustion engine has been actively conducted to date, and many studies and proposals have been made on technologies related to an ignition device and a misfire detection method using combustion ions remaining in the combustion chamber. . In addition to the combustion / misfire determination of the combustion chamber, abnormal combustion determination such as knocking is performed based on the detected combustion / misfire state.

However, in such a technique, a noise waveform is superimposed on the detection signal of the ionic current detected by the ignition device due to a phenomenon caused by the spark plug structure, which reduces the detection accuracy of the combustion / misfire state, This is a factor that hinders the stability of drive control in the engine. In addition, corona noise, discharge end residual noise, etc. are known as noise superimposed by the phenomenon resulting from a spark plug structure. Corona noise has been reported to be a waveform that is detected as an ionic current when a high potential is applied from the ignition coil and the internal charge is temporarily charged inside the spark plug and the internal charge is discharged. . In addition, the discharge end residual noise is detected by a phenomenon in which internal charge is temporarily accumulated in the spark plug due to discharge, and when the internal charge is discharged, the ion current detection unit detects a phenomenon in which the internal charge is attenuated. In response to the phenomenon, it has been reported that a noise waveform is superimposed on the ion current.

Japanese Patent Laying-Open No. 2006-70896 (Patent Document 1) introduces an example of an ignition device for an internal combustion engine. In such a technique, an ignition coil that intermittently supplies a high potential to the spark plug, an ion current detection unit that detects an ionic current, and a comparison unit that compares the potential input from the ion current detection unit and the combustion determination reference level The combustion / misfire state is discriminated using a parameter relating to time or a parameter relating to an area obtained by integration processing with respect to the time axis of the ion detection signal.

JP 2006-70896 A

However, in the ignition device of Patent Document 1, since a parameter related to time is calculated based on a detection signal binarized by a certain threshold value, in some cases, a misfire state in which corona noise is superimposed is erroneously determined as a combustion state. There is a fear. Further, in such an ignition device, since the combustion / misfire determination is performed based on the binarized detection signal and the time parameter, it is extremely difficult to set a discrimination criterion between the combustion state and the misfire state in which the discharge end residual noise is superimposed. This also causes a problem that erroneous detection related to combustion / misfire occurs.

Further, in such an ignition device, since the combustion determination reference level is defined as a constant value and one type by the comparison unit, it is difficult to realize multi-faceted determination with a plurality of determination references. At this time, it can be considered to provide a plurality of comparison units to realize multi-faceted combustion / misfire determination by a plurality of thresholds. However, as the number of circuit elements and signal lines increases, the cost of the ignition device increases. A new problem will occur.

In view of the above problems, the present invention provides an ignition device and a misfire detection method with high detection accuracy related to combustion / misfire determination even when a waveform of corona noise or discharge end residual noise is superimposed on an ion current detection signal. The purpose is to provide.

In order to solve the above problems, the present invention has the following configuration of an ignition device for an internal combustion engine. That is, an ignition coil that supplies a high voltage to the ignition plug, a switching element that intermittently switches the driving state of the ignition coil based on an ignition pulse signal, and an ion current that is discharged from the ignition plug is converted into an analog waveform signal. An ionic current detection circuit and a control circuit for generating the ignition pulse signal based on the analog waveform signal, the control circuit is configured to set a parameter based on an operation state signal determined by an intake pressure of an internal combustion engine and a rotational speed of a crankshaft. An observation interval calculation unit for calculating a calculation range, an A / D conversion unit for processing the analog waveform signal at each A / D timing to generate a digital waveform signal and a digital binarized signal, and calculating a plurality of parameters A parameter calculation unit, and a combustion determination unit that determines combustion or misfire based on the plurality of parameters. Characterized in that it obtain. At this time, an ignition coil that supplies a high voltage to the spark plug, a switching element that intermittently switches the driving state of the ignition coil based on the ignition pulse signal, and an ionic current discharged from the spark plug is converted into an analog waveform signal And a control circuit that generates the ignition pulse signal based on the analog waveform signal, and calculates a deviation processing range based on an operation state signal determined by the intake pressure of the internal combustion engine and the rotational speed of the crankshaft. An observation interval calculation unit, an A / D conversion unit that processes the analog waveform signal at each A / D timing to generate a digital waveform signal and a digital binarized signal, a deviation processing unit that calculates a deviation, And a combustion discriminating unit that discriminates combustion or misfire based on the deviation. Furthermore, an ignition coil that supplies a high voltage to the spark plug, a switching element that intermittently switches the driving state of the ignition coil based on an ignition pulse signal, and an ionic current that is discharged from the spark plug are converted into an analog waveform signal. An ionic current detection circuit and a control circuit for generating the ignition pulse signal based on the analog waveform signal, the control circuit is configured to set a parameter based on an operation state signal determined by an intake pressure of an internal combustion engine and a rotational speed of a crankshaft. An observation interval calculation unit for calculating a calculation range and a deviation processing range; an A / D conversion unit for processing the analog waveform signal at each A / D timing to generate a digital waveform signal and a digital binarized signal; A parameter calculation unit for calculating the parameters of the parameter, a deviation processing unit for calculating the deviation, and the plurality of parameters and It may be characterized in comprising a combustion determination section which determines whether a combustion or misfire on the basis of the deviation.

  Further, it is preferable that the A / D conversion unit sets a predetermined threshold based on the operation state signal and generates the digital binarized signal by a comparison process between the analog waveform signal AGw and the predetermined threshold. Further, the parameter calculation range has a start point provided at a falling position of the ignition pulse signal, an end point provided as a first parameter calculation range provided at a position where ion current during combustion has sufficiently converged, and / or a start point. Preferably, the second parameter calculation range is provided after the discharge end noise generation region, and the end point is provided at a position where the ion current during combustion is sufficiently converged. Further, the plurality of parameters are calculated for the first parameter calculation range, and a time parameter and a waveform parameter calculated based on the digital binarized signal, and the time parameter is divided by the waveform parameter Those consisting of state parameters are preferred. Further, the plurality of parameters are calculated for the first parameter calculation range and calculated based on the digital binarized signal, and the second parameter calculation range is calculated for the digital parameter. A waveform parameter calculated based on a secondary digital waveform signal obtained by extracting and converting a predetermined frequency component of the waveform signal or the analog waveform signal, and a state parameter obtained by dividing the time parameter by the waveform parameter. Is preferred. Further, the time parameter is a maximum response duration of the response time that is the fall time of the digital binarization signal, and the waveform parameter is the number of fall times of the digital binarization signal. The time parameter may be the total response time obtained by integrating the response time that is the fall time of the digital binarization signal, and the waveform parameter may be the digital binarization. It is good also as the frequency | count of response which made the frequency | count of signal fall fall, and the said time parameter is made into the response duration maximum time which becomes the largest among the response time made into the fall time of the said digital binarization signal, and said waveform The parameter may be a subtracted waveform value obtained by subtracting the maximum value and the minimum value of the secondary digital waveform signal using the secondary digital waveform signal, The recording time parameter is a maximum response duration of the response time that is the falling time of the digital binary signal, and the waveform parameter is the secondary digital waveform signal using the secondary digital waveform signal. An integrated waveform value consisting of a sum of values obtained by integrating the area determined by the digital waveform signal and the reference time axis may be set, and the time parameter may be a response time that is a fall time of the digital binarized signal. Of these, the maximum response duration time is set, and the waveform parameter may be a differential waveform value obtained by calculating the frequency of the secondary digital waveform signal using the secondary digital waveform signal.

Furthermore, it is preferable that the deviation processing range is provided with a start point after the discharge end noise generation region and an end point at a position where the ion current during combustion is sufficiently converged. The deviation is calculated for the deviation processing range and provided corresponding to each A / D timing, and is adjacent to the first digital signal value and the first digital signal value in the digital waveform signal. The absolute value is preferably a value obtained by subtracting the second digital signal value. The combustion determination unit compares the state parameter with a state threshold value that is set based on the operation state signal and is defined by a predetermined value of the state parameter, and the state parameter is the state threshold value. It may be determined that the combustion state is exceeded, and the misfire state may be determined if the state parameter is below the state threshold. Further, the combustion determination unit compares the deviation with an upper limit deviation threshold value that is set based on the operation state signal and is defined as a predetermined value of the deviation, and among the deviations, the upper limit deviation An upper limit deviation excess count obtained by counting a deviation exceeding a threshold is obtained, and the upper limit deviation excess count, a threshold value that is set based on the operation state signal and defined as a predetermined value of the upper limit deviation excess count, If the upper limit deviation exceeded number exceeds the threshold number, it is determined that a misfire state has occurred, and if the upper limit deviation excess number falls below the threshold number, it may be determined that a combustion state exists. Further, the combustion determination unit compares the deviation with a lower limit deviation threshold value that is set based on the operation state signal and is defined as a predetermined value of the deviation, and among the deviations, the lower limit deviation A continuous number of times of counting deviations distributed from exceeding a threshold value to falling below the lower limit deviation threshold is acquired, and is set based on the continuous number and the operation state signal, and is set to a predetermined value of the continuous number of times. Comparing with the prescribed continuous threshold number, the combustion state is determined when the continuous number exceeds the continuous threshold number, and the misfire state is determined when the continuous number is less than the continuous threshold number. The threshold frequency is larger than the maximum value of the noise frequency range in which the continuous frequency in the misfire state with discharge end residual noise or corona noise is distributed, and the lower limit continuous frequency in the combustion state is distributed. The minimum value may be set to a range which is smaller than the number of consecutive.

Moreover, in this invention, it is set as the structure of the following misfire detection methods. That is, when the state parameter exceeds the state threshold value, it is determined as a combustion state, and when the state parameter is lower than the state threshold value, a parameter determination step for determining a misfire state, and the upper limit deviation excess number When it exceeds the upper limit deviation, the upper limit deviation determination process for determining the combustion state when the upper limit deviation excess number is less than the threshold number, and the combustion state is determined when the continuous number exceeds the continuous threshold number. A misfire detection method for an internal combustion engine, comprising: a lower limit deviation determination step of determining a misfire state when the continuous number is less than the continuous threshold number.

According to the ignition device for an internal combustion engine according to the present embodiment, digital binarization is performed by generating a plurality of parameters based on the analog waveform signal input to the control circuit and using state parameters determined by the time parameter and the waveform parameter. Since it is possible to appropriately analyze complex fluctuations in the signal, the accuracy of discrimination between the combustion state and the misfire state is improved even when corona noise occurs. In addition, the deviation is calculated based on the analog waveform signal input to the control circuit, and the deviation value in the combustion state and the misfire state and the distribution state of the deviation are compared, thereby effectively detecting the occurrence of the discharge end residual noise. Corona noise can also be detected, and it becomes possible to improve misidentification between the combustion state and the misfire state. Further, when such a determination is made, various threshold values defined based on an operation state signal determined by the intake pressure of the internal combustion engine and the rotational speed of the crankshaft are used as appropriate, so that the driving state of the internal combustion engine is followed. Threshold setting is realized, thereby improving the accuracy of misfire determination.

According to the misfire detection method of the internal combustion engine according to the present embodiment, the misdetection related to misfire / combustion is completely eliminated by synthesizing the determination process using the state parameter and the plurality of determination processes using the deviation. Thus, it is possible to improve the S / N ratio related to the combustion determination signal generated in the combustion determination unit.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a circuit configuration of an ignition device for an internal combustion engine according to the present embodiment.

As shown in FIG. 1A, the ignition device 1 includes an ignition coil 10 that supplies a negative high voltage to the ignition plug PG, and a switching element 20 that intermittently switches the driving state of the ignition coil 10 based on the ignition pulse signal SG. And an ionic current detection circuit 30 that converts the ionic current I discharged by the spark plug PG into an analog waveform signal AGw, and a control circuit 40 that generates the ignition pulse signal SG based on the analog waveform signal AGw.

The switching element 20 includes a semiconductor element such as a power transistor or an IGBT, and drives the primary coil 11 based on the ignition pulse signal SG input from the control circuit 40, thereby generating an induced electromotive force in the secondary coil 12.

The ion current detection circuit 30 includes a bias capacitor 31 that is charged by the ion current I generated in the spark plug PG, a Zener diode 32 that is connected in parallel to the capacitor 31 and regulates the charging voltage value of the capacitor 31, and a Zener The diode 33 includes a diode 33 connected in series to the diode 32 and an amplifier unit 34 connected in parallel to the diode 33. At this time, the anode terminal of the Zener diode 32 is coupled to the anode terminal of the diode 33, and the cathode terminal of the Zener diode 32 is connected in series to the low voltage side of the secondary coil 12. The cathode terminal of the diode 33 is grounded to the ground.

The amplifier unit 34 includes an OP amplifier 34a having an inverting terminal, a non-inverting terminal, and an output terminal, a resistor 34c interposed between the capacitor 31 and the inverting terminal of the OP amplifier 34a, and an inverting terminal and an output of the OP amplifier 34a. A gain resistor 34b connected in parallel to the terminal and a resistor 34d connected between the output terminal of the OP amplifier 34a and the ground are provided. A protection circuit for the OP amplifier 34a may be configured by inserting a diode 34e between the input terminals of the OP amplifier 34a.

The OP amplifier 34a is a circuit in which the non-inverting terminal and the inverting terminal are virtually short because the input impedance at the non-inverting terminal and the inverting terminal is substantially infinite. Accordingly, all the ionic current I between the input terminal and the output terminal flows through the gain resistor 34b, and the voltage between both terminals of the OP amplifier 34a is determined by the value of the gain resistor 34b. That is, the amplification amount of the ionic current flowing through the amplifier unit 34 is left to the value of the gain resistor 34b.

The control circuit 40 has a plurality of functions, and one of the functions is inputted with a signal representing the driving state of the internal combustion engine, and calculates an operation state signal QG described later based on the signal. Still another function is to generate an ignition pulse signal SG based on a predetermined input signal and output it to the switching element 20. Note that the latter function will be described in detail after FIG.

Next, the operation of the ignition device 1 will be described. FIG. 1 (a) shows the flow of the induced current Id when the spark plug PG is discharged. First, when the energization between the primary coil 11 and the ground is suddenly interrupted by the switching element 20, the magnetic field in the primary coil 11 changes according to the counter electromotive force generated by the operation. Along with the change of the magnetic field, a negative high potential is induced in the secondary coil 12, and a discharge is generated in the spark plug PG to explode and burn the air-fuel mixture in the combustion chamber in the internal combustion engine. At the time of such discharge, the induced current Id is guided to the ground through the capacitor 31 and the diode 33 after passing through the secondary coil 12 starting from the ignition coil PG. At this time, the potential across the capacitor 31 is charged to the breakdown potential of the Zener diode 32.

When all the energy accumulated in the secondary coil 12 is released by such discharge, an ionic current flows in the direction of the spark plug PG by the potential charged in the capacitor 31 as described above, and then remains in the combustion chamber of the internal combustion engine. The combustion ions that propagate are guided to the ground. Specifically, as shown in FIG. 1B, the ionic current I is guided from the ground to the resistor 34d, and then the output section of the OP amplifier 34a, the gain resistor 34b, the resistor 34c, the capacitor 31, the secondary coil 12, and the like. It flows in sequence, propagates combustion ions in the ignition coil PG, and is guided to the ground. The ionic current detection circuit 30 detects the output potential of the OP amplifier 34a as an ionic current value, and outputs the analog waveform signal AGw generated thereby to the control circuit 40. Here, the case where the air-fuel mixture in the combustion chamber is combusted has been described. However, the present invention is not limited to this, and when the air-fuel mixture in the combustion chamber is not combusted, for example, the charge accumulated in the spark plug PG is discharged / damped. Even when the noise phenomenon occurs, the ion current I is detected by the ion current detection circuit 30 as described above, and at this time, the noise waveform generated by the noise phenomenon is output to the analog waveform signal AGw. . Further, when the combustion state is accompanied by some noise phenomenon, the noise waveform is further superimposed on the combustion waveform described above.

As described above, in the ignition device 1 including the ion current detection circuit 30, the accuracy of combustion / misfire determination may be reduced depending on the state of the noise waveform superimposed on the ion current I. Therefore, in the present embodiment, by using the state parameter Ps and the deviation Dv generated in the control circuit 40, improvement in the determination accuracy of combustion / misfire is achieved. Hereinafter, the function of the control circuit will be described in detail with reference to FIG. 2, and the state parameter and the deviation Dv will be clarified with reference to FIGS.

FIG. 2 shows the configuration of the calculation unit in the control circuit according to the present embodiment. The control circuit 40 used in the present embodiment is an ECU 40 (Engine Control Unit), and a memory unit and a control unit that are other components of the ECU 40 are not shown for convenience.

As shown in the figure, the ECU 40 calculates a parameter calculation range Winp (first parameter calculation range in claim 9) and a deviation processing range Wind based on an operation state signal QG determined by the intake pressure of the internal combustion engine and the rotational speed of the crankshaft. The analog waveform signal AGw generated by the observation interval calculation unit 40a and the ion current detection circuit 30 is processed for each A / D timing Tc, and the digital waveform signal DGw and the digital binarization signal DGs are generated. / D conversion unit 40b, parameter calculation unit 40c for generating a plurality of parameters based on the digital waveform signal DGw and / or the digital binarization signal DGs in the parameter calculation range Winp, and the digital of the deviation processing range Wind Deviation processing unit 4 for obtaining deviation Dv based on waveform signal DGw And d, comprises a combustion determination unit 40e for discriminating the combustion or misfire on the basis of a such a plurality of parameters and deviation Dv.

The observation interval calculation unit 40a sequentially calculates a plurality of calculation intervals based on the operation state signal QG calculated inside the ECU 40, and causes the parameter calculation unit 40c to output the parameter calculation range Winp among the plurality of calculation intervals. The deviation processing range Wind is output to the deviation processing unit 40d. Here, the operation state signal QG is a signal that is calculated over time by the ECU 40 in accordance with the operation state of the internal combustion engine (for example, the running state of the automobile), and the intake pressure and the rotation of the crankshaft in the internal combustion engine. The number is a signal quantified according to the operation state. At this time, the operation state signal QG includes a parameter related to the rotational speed of the crankshaft in the internal combustion engine and a parameter related to the intake pressure. In the parameter calculation range Winp, parameters described later are calculated, and in the deviation calculation range Wind, a deviation Dv described later is calculated.

The A / D conversion unit 40b discretely processes the analog waveform signal AGw at each A / D timing Tc, and the value of the analog waveform signal AGw is converted into a signal stepwise corresponding to the A / D timing Tc. A signal DGw is generated. In addition, the analog waveform signal AGw is compared with the predetermined threshold value Vth to obtain either High or Low value, and the digital binarized signal DGs discretely processed at each A / D timing Tc is also generated. Then, the A / D conversion unit 40b causes the digital waveform signal DGw to be output to the parameter calculation unit 40c and the deviation processing unit 40d, while causing the digital binarization signal DGs to be output only to the parameter calculation unit 40c. The predetermined threshold value Vth is a threshold value calculated by the A / D conversion unit 40b, but is variably calculated based on the operating state signal QG, and thus a preferable setting that follows the operating state of the internal combustion engine. Realized.

The parameter calculator 40c calculates a plurality of parameters within the parameter calculation range Winp calculated by the observation interval calculator 40a. The plurality of parameters include a time parameter Pt calculated based on the digital binarized signal DGs, a waveform parameter Pw calculated based on the digital waveform signal DGw or the digital binarized signal DGs, and a time parameter Pt. The state parameter Ps is divided by the parameter Pw, and the state parameter Ps is output to the combustion determination unit 40e. In the present embodiment, the time parameter Pt is the response duration maximum time Tbd, the waveform parameter Pw is the response count Cca, and the state parameter Tbd / Cca calculated by this is used. Details of these parameters will be described with reference to FIGS. 3 to 5, and other modes of the state parameters will be described later.

The deviation processing unit 40d calculates the deviation Dv for each A / D timing Tc within the range of the deviation processing range Wind calculated as described above. The deviation Dv will be described in detail later.

The combustion determination unit 40e calculates a threshold value corresponding to the input state parameter Ps, that is, a state threshold value Pd that is set based on the operation state signal QG and is defined as a predetermined value of the state parameter Ps. Also, based on the input deviation Dv, the upper limit deviation threshold Vsu, the upper limit deviation excess number Nn, the threshold number Nnd, the lower limit deviation threshold Vsl, the continuous number Nc, and the continuous threshold number Ncd are calculated according to the value of the operation state signal QG. To do. And the combustion discrimination | determination part 40e discriminate | determines a combustion state or a misfire state based on these numerical values, produces | generates a combustion signal or a misfire signal according to this discrimination | determination result, and outputs it to the switching element 20 at an appropriate timing. To do. The plurality of numerical values and the determining operation will be described in detail later.

FIG. 3 shows an analog waveform signal AGw and a digital binarization signal DGs corresponding to the ignition pulse signal SG. In this figure, the waveform states are shown separately for (a) a normal combustion state and (b) a normal misfire state. The normal combustion state refers to a combustion state in which corona noise and discharge end residual noise are not superimposed, and the normal misfire state refers to a misfire state in which corona noise and discharge end residual noise are not superimposed. Also, the analog waveform signal AGw shows a predetermined threshold value Vth set by the A / D converter 40b, a parameter calculation range Winp (first parameter calculation range in claim 5), and a deviation processing range Wind. In the figure showing the digital binarization signal DGs, the response duration maximum time Tbd and the response count Cca are additionally shown.

  With reference to Fig.3 (a), each waveform when the air-fuel | gaseous mixture supplied in a combustion chamber burns appropriately is demonstrated. First, when the ignition pulse signal SG is input, a discharge start noise α appears in the analog waveform signal AGw in response to the rising end of the ignition pulse signal SG. Then, after the discharge state is maintained for a predetermined time, the discharge end noise β appears, and then the combustion waveform γ1 appears. At this time, the digital binarized signal DGs is subjected to a comparison process of the signal value of the analog waveform signal AGw by a predetermined threshold value Vth set based on the operation state signal QG, and a signal is generated as follows. That is, since the discharge start noise α appears in the analog waveform signal AGw in a state exceeding the predetermined threshold Vth, in response to this, the pulse waveform S1 falls in the digital binarized signal DGs. Thereafter, similarly, a pulse waveform S2 corresponding to the discharge end noise β and the combustion noise γ1 is generated. In the figure, since there is no portion that falls below the predetermined threshold Vth from when the discharge end noise β exceeds the predetermined threshold Vth until the combustion waveform γ1 falls below the predetermined threshold Vth, the length of the time taken A pulse waveform S2 corresponding to is generated.

On the other hand, FIG. 3B shows each waveform when the air-fuel mixture supplied into the combustion chamber is not combusted and is in a normal misfire state. When the ignition pulse signal SG is input, the discharge start noise α and the discharge end noise β appear in order in the analog waveform signal AGw as described above. However, since the air-fuel mixture is not burned, the combustion waveform γ1 does not appear after the discharge end noise β appears. At this time, the digital binarized signal DGs is generated as follows using a predetermined threshold Vth. That is, the pulse waveform S1 is generated in the digital binarization signal DGs in response to the waveform in which the discharge start noise α exceeds the predetermined threshold value Vth. Thereafter, the pulse waveform S2 corresponding to the discharge end noise β is generated according to the time exceeding the predetermined threshold value Vth.

As described above, in FIG. 3, the case where noise exceeding the predetermined threshold Vth is not superimposed after the occurrence of the discharge end noise β in the analog waveform signal AGw has been described. However, in actuality, when a misfire occurs, the charge is accumulated inside the spark plug PG, so that the ionic current related to noise is further detected by the discharge action of the accumulated charge, whereby the analog waveform signal AGw The noise waveform will be superimposed on. Hereinafter, the combustion / misfire state with such a noise waveform will be described.

With reference to Fig.4 (a), the combustion state accompanied by a corona noise is demonstrated. First, when the ignition pulse signal SG is input, the discharge start noise α and the discharge end noise β appear in the analog waveform signal AGw as described above. Thereafter, the combustion waveform γ2 appears, and it can be seen that the corona noise ω is superimposed on a part of the combustion waveform γ2. At this time, the signal value of the analog waveform signal AGw is compared with the digital binarized signal DGs according to the predetermined threshold value Vth as follows. That is, the analog waveform signal AGw appears in a state where the discharge start noise α exceeds the predetermined threshold value Vth, and accordingly, the pulse waveform S1 falls in the digital binarized signal DGs. Thereafter, the ignition pulse signal S2 falls in response to a portion exceeding the predetermined threshold Vth in the combustion waveform γ2 on which the discharge end noise and the corona noise are superimposed. Therefore, even when corona noise is involved during combustion, a relatively long pulse waveform S2 is generated by the combustion waveform γ2, so that the influence of corona noise is reduced. That is, in the digital binarization signal DGs in the combustion state with corona noise, a waveform having a small difference from the digital binarization signal DGs in the normal combustion state is generated.

On the other hand, in the misfire state with corona noise shown in FIG. 4B, after the discharge start noise α and the discharge end noise β appear, further, the corona noise γ3 appears in an intermittently repeated state. . It can be seen that in the section where the corona noise γ3 appears, the analog waveform signal AGw appears in a state extending above and below the predetermined threshold value Vth. At this time, the signal value of the analog waveform signal AGw is compared with the digital binarized signal DGs according to the predetermined threshold value Vth as follows. That is, since the discharge start noise α and the discharge end noise β appear in the analog waveform signal AGw in a state exceeding the predetermined threshold value Vth, the pulse waveforms S1 and S2 fall in response thereto. Thereafter, the ignition pulse signals S3 to S8 further fall intermittently according to the waveform state of the corona noise γ3 that occurs intermittently.

Further, FIG. 5 shows a misfire state with residual noise at the end of discharge. First, when the ignition pulse signal SG is input, in the analog waveform signal AGw, the discharge start noise α and the discharge end noise β appear, and then the discharge end residual noise γ4 appears in a gradually attenuated state. I understand. In addition, since the discharge end residual noise γ4 shows a gentle attenuation waveform, a waveform portion lower than the predetermined threshold Vth does not appear intermittently. At this time, the digital binarized signal DGs is generated as follows. First, as described above, the pulse waveforms S1 and S2 corresponding to the discharge start noise α and the discharge end noise β fall. Thereafter, the ignition pulse signal S3 appears for a predetermined time in accordance with the waveform state of the discharge end residual noise γ4 that gradually attenuates. Accordingly, even in this case, the digital binarization signal DGs in the misfire state accompanied by the discharge end residual noise γ4 generates a waveform with little difference from the digital binarization signal DGs in the normal combustion state. . In general, in the combustion state, it cannot be clearly distinguished whether or not the discharge end residual noise is superimposed, and the object of the present embodiment is between the combustion state and the misfire state. Since there is a sharp distinction, the aspect of the combustion state with the discharge end residual noise is assumed to be included in the normal combustion state.

Based on the digital binarization signal DGs generated as described above, the state parameter Tbd / Cca used when performing the discrimination of combustion / misfire is calculated as follows. First, returning to FIG. 3A, the calculation process of the time parameter Pt in the combustion state will be described. As shown in the figure, first, the parameter calculation range Winp, which is a detection target for calculating each parameter, is set by the observation interval calculation unit 40a. The parameter calculation range Winp has a start point provided at the falling position of the ignition pulse signal SG and an end point provided at a position where the ion current during combustion has sufficiently converged. The analog waveform signal AGw has a relationship of varying the waveform state in accordance with the operation state of the internal combustion engine. Therefore, even in the parameter calculation range Winp, the operation state signal is set to correspond to the relationship. An appropriate range setting is dynamically performed based on QG. In this embodiment, the maximum response duration Tbd that is the maximum of the falling time of the digital binarized signal DGs is used as the time parameter Pt. The maximum response duration Tbd is calculated as follows. That is, each response time Tn corresponding to the pulse waveform Sn (S1 to S2 in FIG. 3A) formed in the digital binarized signal DGs is calculated. Then, the pulse waveform S2 having the maximum time among the response times Tn is selected, and the response time T2 of the pulse waveform S2 is set as the response duration maximum time Tbd. Similarly, in the normal misfire state (see FIG. 3b), the maximum response duration Tbd is T2, and in the combustion state with corona noise (see FIG. 4a), the maximum response duration Tbd is T2. In the misfire state with corona noise (see FIG. 4b), the maximum response duration Tbd is T5, and in the misfire state with discharge end residual noise (see FIG. 5), the maximum response duration Tbd is T3. Returning to FIG. 3A again, the calculation process of the waveform parameter Pw in the combustion state will be described. In the present embodiment, the response number Cca obtained by counting the number of falling times of the digital binarization signal DGs is used as the waveform parameter Pw. The response count Cca is calculated as follows. That is, the number of responses Cca is the number n of pulse waveforms Sn (n = 2 in FIG. 3a) formed in the digital binarized signal DGs, that is, the number of falling times of the digital binarized signal DGs is counted. It is a thing. Similarly, in the normal misfire state (see FIG. 3b), the response count Cca is counted as “2”, and in the combustion state with corona noise (see FIG. 4a), the response count Cca is counted as “2”. In the misfire state with corona noise (see FIG. 4b), the response count Cca is counted as “8”, and in the misfire state with discharge end residual noise (see FIG. 5), the response count Cca is counted as “3”. Is done. Thereafter, the response duration maximum time Tbd calculated as described above is divided by the response count Cca, and the numerical value obtained by this is used as the state parameter Tbd / Cca.

In general, in each of the above-described combustion states and misfire states accompanied by residual noise at the end of discharge, the response duration maximum time Tbd in those states tends to show values that are close to each other under the same operating conditions. In addition, the number of responses Cca at this time also tends to show substantially equal values in those states. On the other hand, the maximum response duration Tbd in the misfire state with corona noise tends to be shorter than the maximum response duration Tbd in those states. Further, the number of responses Cca in a misfire state with corona noise has a property of showing a very large value compared to the number of responses Cca in other states because corona noise γ3 appears intermittently. Therefore, by using the characteristic that appears in the difference and using the state parameter Tbd / Cca obtained by dividing the maximum response duration Tbd by the number of responses Cca, the following is distinguished from the misfire state with corona noise as follows. Is achieved. That is, in each of the above-described combustion states and misfire states with discharge end residual noise, the response duration maximum time Tbd and the response count Cca in each state are values approximate to each other. The values of the state parameter Tbd / Cca calculated by the response count Cca are substantially equal to each other. On the other hand, in the misfire state with corona noise, the value of the maximum response duration time Tbd is short and the value of the response count Cca is large, so that the value of the state parameter Tbd / Cca is significantly reduced. Therefore, by setting the state threshold value Pd to a predetermined value related to the state parameter Tbd / Cca in advance and comparing the state parameter Tbd / Cca with the state threshold value Pd, it is possible to determine whether or not the misfire state is accompanied by corona noise. Realized. Even in the state threshold value Pd, it is appropriately set based on the operation state signal QG. Although other state parameters (Tbi / Ccp, Tbd / Bvp, Tbd / Bin, Tbd / Bca), which will be described in detail later with reference to FIG. 11, are slightly changed in the parameters used. Similar to the state parameter Tbd / Cca, it has a physical property indicating a low value in a misfire state with corona noise.

However, even if the combustion / misfire determination is performed using the state parameter Tbd / Cca, the state parameter Tbd / Cca in the misfire state with the corona noise and the state parameter Tbd / Cca in the other state depending on the operation state of the internal combustion engine. It may be difficult to distinguish between Therefore, the discrimination accuracy is further improved by using the deviation Dv calculated based on the digital waveform signal DGw as follows. First, the relationship between the ion current I and the deviation Dv during normal combustion will be described with reference to FIG. In the graph shown here, the detection potential of the ion current I (here, the value of the digital waveform signal DGw) is on the left side of the vertical axis, the value of the deviation Dv is on the right side of the vertical axis, and the A / D timing Tc is on the horizontal axis. It is shown. At this time, the origin portion of the A / D timing Tc shown in the figure is matched with the start point of the deviation processing range Wind, and the end portion of the A / D timing Tc is matched with the end point of the deviation processing range Wind. Further, in the graph, a lower limit deviation threshold value Vsl is additionally illustrated at a position of a predetermined deviation. Here, the deviation Dv is a value provided corresponding to each A / D timing Tc as shown in FIG. 6A, and includes the first digital signal value S1 in the digital waveform signal DGw, and The absolute value of the value obtained by subtracting the adjacent second digital signal value. The deviation processing range Wind in which the deviation Dv is detected is set as follows. Referring to FIG. 3A, it can be seen that the deviation processing range Wind is set at a position where the start point is provided after the discharge end noise generation region β and the ion current during combustion is sufficiently converged. That is, the deviation processing range Wind is set to a range that is avoided from the influence of the discharge start noise α and the discharge end noise β, and thereby the deviation Dv shows a characteristic distribution state markedly in the combustion state as described below. It becomes. Since the analog waveform signal AGw has a relationship in which the waveform state varies in accordance with the operation state of the internal combustion engine, the deviation processing range Wind is based on the operation state signal QG so as to correspond to the relationship. The appropriate range setting is dynamically implemented.

As shown in FIG. 6A, the deviation Dv calculated as described above is continuously plotted at each A / D timing Tc position. At this time, it can be seen that the deviation Dv continuously shows a relatively large value at the beginning of the deviation processing range Wind, and thereafter tends to converge to substantially zero after a predetermined time. Thus, in the combustion state as shown in the figure, the digital waveform signal DGw at the beginning of the deviation processing range Wind is shifted from the sudden decrease curve to the gentle decrease curve, so that the digital waveform signal DGw The deviation Dv calculated based on this also decreases sharply accordingly. On the other hand, since the waveform state of the digital waveform signal DGw after the middle of the deviation processing range Wind is shifted from the transitional decreasing curve to the converged state, the deviation Dv decreases accordingly, and the latter half of the deviation processing range Wind. In the part, it converges to substantially zero. At this time, the distribution state of the deviation Dv at the beginning of the deviation processing range Wind is a characteristic portion of the waveform of the deviation Dv during combustion. In addition, in the waveform of the deviation Dv, there is a tendency that a transition waveform is not displayed as in the waveform of the digital waveform signal DGw, but is immediately reduced to a substantially zero value, and then the convergence waveform is discontinuously displayed. Next, the relationship between the ion current I and the deviation Dv in a misfire state with corona noise will be described with reference to FIG. Since the graph shown here shows a waveform without combustion, only the waveform of the corona noise appears. As shown in the figure, the waveform of the digital waveform signal DGw shows that the columnar distribution with a short time width is intermittently maintained, and the maximum value of each deviation distribution tends to be very high. The waveform of the deviation Dv also corresponds to the waveform state of the digital waveform signal DGw, and a columnar deviation distribution appears. At this time, the maximum value of the deviation Dv in the normal combustion state is slightly less than 0.3 (V) (see FIG. 6a), whereas the maximum value of the deviation Dv in FIG. (V) will be indicated. Furthermore, with reference to Fig.8 (a), the relationship between the ion current I and the deviation Dv in the misfire state with a discharge end residual noise is demonstrated. Since the graph shown here is not accompanied by combustion as described above, only the waveform of the discharge end residual noise appears. As shown in the figure, the waveform of the digital waveform signal DGw in this case shows a gentle decreasing waveform. In response to this waveform state, in the waveform of the deviation Dv, the difference between adjacent signal values in the digital waveform signal DGw can be kept low, so that the deviation Dv converges to substantially zero over the entire range of the deviation processing range Wind. To do.

Therefore, paying attention to the waveform state of the deviation Dv having the characteristics corresponding to the respective combustion / misfire states, the combustion / misfire determination is realized as follows. First, referring back to FIG. 6A, the upper limit deviation threshold Vsu used for misfire / combustion determination will be described. As shown in the figure, in this embodiment, the deviation Dv = 0.3 (V), which is the lower limit defining standard, is shown as the first standard for defining the upper limit deviation threshold Vsu. The lower limit standard is defined as follows. That is, the internal combustion engine ignition device 1 in this embodiment opens the deviation processing range Wind for each ignition cycle and observes the deviation Dv. At this time, even if the operation state signal QG is constant, the deviation waveforms are not always the same, and a predetermined “variation” occurs. Accordingly, the experimental data of the “variation” is totaled in advance corresponding to each operating condition, and the upper limit deviation threshold Vsu is set to a level larger than any deviation Dv in the normal combustion state based on the experimental data. . Accordingly, in this embodiment, if the upper limit deviation threshold Vsu is defined as the deviation Dv = 2 (V), the upper limit deviation threshold Vsu is set to a value larger than the lower limit regulation standard (Dv = 0.3 V). Therefore, even if “variation” occurs in the deviation waveform under a certain operating condition, the deviation Dv does not exceed the upper limit deviation threshold Vsu. Since the waveform of the deviation Dv has a relationship in which the waveform state varies in accordance with the operating state of the internal combustion engine as described above, even if it is at the upper limit deviation threshold Vsu, it is necessary to correspond to this relationship. An appropriate threshold value is dynamically set based on the operation state signal QG. As described above, the upper limit deviation threshold Vsu used in the present embodiment will be described below assuming that the deviation Dv = 2 (V). FIG. 6B shows a state in which the upper limit deviation excess number Nn is counted in the normal combustion state. Here, the upper limit deviation excess number Nn is a count value obtained by counting the deviation Dv exceeding the upper limit deviation threshold Vsu among the deviations Dv distributed in the deviation processing range Wind. As shown in FIG. 6A, since the upper limit deviation threshold Vsu is set to the deviation Dv = 2 (V), there cannot exist a distribution of the deviation Dv exceeding the upper limit deviation threshold Vsu. Accordingly, as shown in FIG. 6B, the counter of the upper limit deviation excess number Nn in the normal combustion state shows “0” uniformly throughout the deviation processing range Wind. On the other hand, the upper limit deviation excess number Nn in the case of a misfire state with corona noise will be described with reference to FIG. First, the upper limit deviation threshold Vsu will be described. As a second reference for defining the upper limit deviation threshold Vsu, when corona noise occurs under the same driving conditions as the combustion state, the value of the upper limit deviation threshold Vsu is a waveform of the deviation Dv. Is set such that there is a waveform portion exceeding the upper limit deviation threshold Vsu. At this time, when performing such setting, as described above, the waveform of the deviation Dv is set to the upper limit deviation threshold Vsu in the misfire state with corona noise based on the experimental data of “variation” in advance corresponding to each operating condition. Set so that there are more parts. Therefore, since the upper limit deviation threshold Vsu adopted in the present embodiment with the deviation Dv = 2 (V) is also studied, the second standard for defining the upper limit deviation threshold Vsu has been studied. , The existence of the deviation Dv is confirmed at a value higher than the upper limit deviation threshold Vsu. As a result, as shown in FIG. 7B, when the counter of the upper limit deviation excess number Nn is activated every time the deviation Dv exceeding the upper limit deviation threshold Vsu is detected, as a result, the upper limit deviation excess number Nn is “4”. You will get On the other hand, in the case of a misfire state with discharge end residual noise, as shown in FIG. 8A, there is no distribution of the deviation Dv exceeding the upper deviation threshold Vsu, so the result of the upper deviation excess number Nn is “0”. obtain. At this time, the threshold number Nnd is set to a predetermined value of the upper limit deviation excess number, the threshold number Nnd is compared with the upper limit deviation threshold number Nn, and if the upper limit deviation excess number Nn exceeds the threshold number Nnd, a misfire state is set. By setting the combustion state when the upper limit deviation excess number Nn is lower than the threshold number Nnd, it is possible to determine whether or not it is a misfire state with corona noise. Needless to say, the waveform of the deviation Dv has a relationship in which the waveform state varies in accordance with the operation state of the internal combustion engine. Therefore, even if the threshold number of times is Nnd, the operation state signal It is preferable that an appropriate threshold value is dynamically set based on QG. Specifically, in the normal combustion state / misfire state with corona noise / misfire state with discharge end residual noise, the upper limit deviation excess number Nn is set to “0” / “4” / “0”, respectively. Therefore, it is defined that the value of the threshold number Nnd is calculated to be “2” based on the operation state signal QG, for example. This makes it possible to distinguish between a misfire state with corona noise and a misfire state with normal combustion state / discharge end residual noise. Although the typical phenomena in each combustion state have been described with reference to FIGS. 6 to 8, the present invention is not limited to this, and the combustion / misfire determination is reliably performed by the above method even in other combustion states. . That is, since the upper limit deviation excess number Nn in the combustion state with corona noise tends to be lower than the value of the upper limit deviation excess number Nn in the misfire state with corona noise, the threshold number Nnd is adapted to this tendency. Further, it is possible to prevent erroneous determination between a combustion state with corona noise and a misfire state with corona noise. Specifically, in the case of a combustion state with corona noise, the deviation Dv value can be set to an appropriate threshold value for the upper limit deviation threshold Vsu because the deviation waveform indicating the corona noise phenomenon is suppressed to a low value by the combustion waveform. The combustion / misfire determination based on the upper limit deviation excess number Nn is appropriately performed. In addition, the number of appearances of so-called columnar corona noise waveforms tends to decrease due to the high pressure in the combustion chamber during combustion, etc., so that the influence on the upper limit deviation count Nn can be kept low. The combustion / misfire determination based on the upper limit deviation excess number Nn is appropriately performed. Furthermore, if the combustion waveform shows a very low distribution even in the combustion state with corona noise, or if it is difficult to show a difference in the deviation waveform in each combustion / misfire state depending on the operation state, the upper limit is set under certain operating conditions. By varying the deviation threshold number Vsu, the distribution of the upper limit deviation excess number Nn at the time of combustion and the upper limit deviation excess number Nn at the time of misfiring corresponding to the various upper limit deviation threshold values Vsu is processed. It is preferable to set an upper limit deviation threshold Vsu that allows threshold setting (setting of the threshold number Nnd) of the upper limit deviation excess number Nn during combustion and the upper limit deviation excess number Nn during misfire.

  Next, the distinction between the normal combustion state and the misfire state with the discharge end residual noise will be described, and further, the case where the misfire state is not determined even if the upper limit deviation threshold Vsu is used due to the operation state. The determination of the misfire state with corona noise will be described. Returning to FIG. 6A, the lower limit deviation threshold Vul used when determining the combustion / misfire will be described. As shown in the figure, the lower limit deviation threshold Vsl is set to a level where the deviation Dv is “0.1”. FIG. 6C shows a state in which the number of consecutive times Nc in the normal combustion state is counted. Here, the number of consecutive times Nc is a value obtained by continuously counting the deviation Dv distributed between the deviation Dv distributed within the deviation processing range Winp and exceeding the lower limit deviation threshold Vsl and below the lower limit deviation threshold Vsl. Say. Specifically, as shown in FIG. 6 (a), after the deviation processing range Wind is opened, when the lower limit deviation threshold value Vsl is exceeded, the counter of the continuous number Nc is operated, and again when the lower limit deviation threshold value Vsl is lowered. The counter for the number of consecutive times Nc is stopped. As a result, as shown in FIG. 6C, in this embodiment, “15” is obtained as the number of consecutive times Nc in the normal combustion state. On the other hand, in the case of a misfire state with corona noise, the deviation Dv is intermittently distributed in a columnar shape as shown in FIG. Further, it can be observed that the lower limit deviation threshold value Vsl crosses the columnar distribution (Y1, Y2,...) At the deviation Dv. Therefore, in the misfire state with corona noise, the counter of the continuous number Nc is operated as follows. First, when the deviation processing range Wind is opened, in the columnar distribution Y1 of the deviation Dv, deviations exceeding the lower limit deviation threshold value Vsl are already distributed, so the number of consecutive times Nc immediately starts to be counted, and the deviation Dv becomes equal to the lower limit deviation threshold value Vsl. When it falls, the count of the continuous number Nc is stopped (Y1: count result “2”). Thereafter, although the deviation Dv exceeding the lower limit deviation threshold value Vsl appears again, the deviation Dv immediately falls below the lower limit deviation threshold value Vsl. Accordingly, in response to this, the count of the consecutive times Nc immediately stops (Y2: count result “1”) ). Further, the number of consecutive times Nc is counted again according to the appearance of the columnar distribution Y3 (Y3: count result “5”). The maximum value among the plurality of consecutive times Nc is used as the actual number of consecutive times Nc (in this embodiment, the count result “5”). On the other hand, in the misfire state with the discharge end residual noise, as shown in FIG. 8A, the deviation Dv exceeding the lower limit deviation threshold Vsl is not distributed. The number of consecutive times Nc is set to “0”. At this time, the continuous threshold number Ncd is set to a predetermined value of the continuous number Nc, the continuous threshold number Ncd is compared with the continuous number Nc, and when the continuous number Nc exceeds the continuous threshold number Ncd, the combustion state is set. When the number of times Nc is less than the continuous threshold number of times Ncd, the determination of combustion / misfire is realized by setting the misfire state. Specifically, in the normal combustion state / misfire state with corona noise / misfire state with discharge end residual noise, the number of consecutive times Nc is set to “15” / “5” / “0”, respectively. For example, the value of the continuous threshold number Nnd is defined to be calculated as “8” based on the operation state signal QG. Thereby, a combustion state and another misfire state are clearly distinguished. As described above, the waveform of the deviation Dv has a relationship in which the waveform state varies variously according to the operating state of the internal combustion engine. An appropriate threshold value setting is dynamically performed based on the operation state signal QG. Similarly to the setting of the upper limit deviation threshold value Vsl, when there is no difference in the deviation waveform in each combustion / misfire state depending on the operation state, the difference in the combustion / misfire state may not appear even for the number of consecutive times Nc. Even in this case, the value of the lower limit deviation threshold value Vsl is changed under a certain condition, and the distribution of the continuous number of times Nc at the time of combustion and the continuous number of times Nc at the time of misfiring corresponding to the various lower limit deviation threshold values Vsl It is preferable to set the lower limit deviation threshold number Vsl that allows threshold setting (setting of the continuous threshold number Ncd) between the continuous number Nc during combustion and the continuous number Nc during misfire based on such data. .

  Here, the criteria for setting the above-mentioned continuous threshold number Ncd will be described. In FIG. 9, a plurality of experiments are performed in advance in correspondence with a predetermined operating condition signal QG, and the observation result corresponding to a certain condition among the observation results of the continuous number Nc observed by such an experiment is representative. Is shown. In this observation result, the number of A / D timings Tc from the time when the value exceeds the lower limit deviation threshold Vsl to the time when the value falls below the lower limit deviation threshold, that is, the number of consecutive times Nc is shown on the horizontal axis. Also, on the vertical axis, the occurrence frequency Nf of the continuous number Nc observed by performing a plurality of experiments is divided into a combustion state / a misfire state with corona noise / a misfire state with discharge end residual noise. Each is shown. Referring to FIG. 9, in the observation result of the continuous number Nc in the combustion state, the continuous number Nc is distributed in the combustion frequency range in the range of about 20 to 60 times. Moreover, in the observation result of the continuous number Nc in the misfire state with the corona noise, the continuous number Nc is distributed in the number of times range of 0 to 15 times. Furthermore, in the observation result of the continuous number Nc in the misfire state with the discharge end residual noise, the continuous number Nc is distributed in the number of times range of about 0 to 5 times. At this time, the number of times indicated by the large number of consecutive times Nc among the number of times in the misfire state with corona noise and the number of times in the misfire state with discharge end residual noise is defined as the number of times of noise. When observing the observation result, it is understood that the continuous number Nc is not distributed at all in the section from the maximum value Nmax in the noise frequency range to the minimum value Nmin in the combustion frequency range. Therefore, the continuous threshold frequency Ncd is provided in a section from the maximum value Nmax in the noise frequency range to the minimum value Nmin in the combustion frequency range in which the continuous frequency Nc in the combustion state is distributed, so that proper combustion / misfire determination can be performed. Realized. As described above, the combustion determination unit 40e compares the number of consecutive times Nc and the number of consecutive threshold values Ncd to determine the combustion / misfire state. Note that the relationship between the number of consecutive times Nc and the occurrence frequency Nf also has a relationship in which the distribution state varies in accordance with the operating state of the internal combustion engine. An appropriate threshold value is dynamically set based on the result and the operation state signal QG.

FIG. 10 shows a flowchart relating to an algorithm for determining combustion / misfire. This flowchart is representative of an example for realizing the present embodiment. First, before the determination routine described in the figure starts, each parameter in the parameter calculation range Winp is calculated for each A / D timing Tc by the parameter calculation unit 40c and is stored in a predetermined memory unit. Further, the deviation processing unit 40d calculates the deviation Dv in the deviation processing range Wind for each A / D timing Tc and holds it in a predetermined memory unit. Then, after both the parameter calculation range Winp and the deviation processing range Wind are closed, the determination routine is started after all necessary data holding is completed. When such a determination routine is started, the calculation unit incorporated in the ECU 40 first compares the combustion possibility time Tbt calculated by the parameter calculation unit 40c with the ignition near time Mis, and Tbt> Mis. In this case, it is determined that the combustion possibility is A, and if Tbt <Mis, the misfire state B is determined (S101). Note that the combustion possibility time Tbt refers to a time range from the end of the ignition pulse signal SG to the end of the response maximum response time Tbd, as shown in FIG. The near ignition time Miss indicates a time range from the end of the ignition pulse signal SG until the discharge end noise β disappears. In general, the relationship of Tbt> Mis is established in the combustion state as shown in FIG. 3A, and in the case of misfire, the relationship of Tbt <Mis is established as shown in FIG. A relationship is established. Thus, when it is determined that the combustion possibility is A, the state parameter Tbd / Cca is compared with the state threshold value Pd. If (Tbd / Cca)> Pd, it is determined that the combustion possibility is A, When (Tbd / Cca) <Pd, it is determined that the misfire state B is present (S102: parameter determination step in claim 18). Thereafter, the upper limit deviation excess number Nn is calculated (S103). When the upper limit deviation excess number Nn is less than the threshold number Nnd, it is determined that there is combustion possibility A, and when the upper limit deviation excess number Nn exceeds the threshold number Nnd, misfire occurs. The state B is determined (S104: upper limit deviation determining step in claim 18). After that, the number of consecutive times Nc is counted (S105). When the number of consecutive times Nc exceeds the continuous threshold number of times Ncd, it is determined as the combustion state AA. (S106: lower limit deviation determination process in claim 18). In this manner, the combustion state AA or the misfire state B is determined, and a combustion determination signal or a misfire determination signal is generated according to each determination state (S107, S108). The determination signal is output (S109), and is used when the ignition pulse signal SG is generated. When the above determination process is completed, the determination routine is ended accordingly. Thereafter, after the parameter calculation range Winp and the deviation processing range Wind corresponding to the next ignition cycle are closed, the determination routine is started again. The Rukoto.

In this embodiment, the state parameter Ps used in S102 is described as Tbd / Ccp. However, the present invention is not limited to this, and various parameters can be used as appropriate. For example, the total response time Tbi obtained by integrating the response time Tn and the response count Ccp obtained by counting the number of falling times of the digital binarized signal DGs are used to divide the total response time Tbi by the response count Ccp. A new state parameter (Tbi / Ccp) may be used. At this time, the state threshold value Pd used in S102 needs to be appropriately changed according to the new state parameter (Tbi / Ccp). Here, the total response time Tbi will be described with reference to FIG. As shown in the figure, the falling time corresponding to each of the pulse waveforms Sn formed in the digital binarized signal DGs is defined as a response time Tn. At this time, the total response time Tbi is calculated as the sum of the response times Tn. For example, the total response time Tbi in FIG. 3A is T1 + T2, and the total response time Tbi in FIG. 4B is T1 +. As a result, a new state parameter Tbi / Ccp is calculated based on the calculated time parameter (total response time Tbi) and the number of responses Ccp, and the state parameter Tbi / Ccp is used when the misfire determination is performed in S102. Used.

Further, as other state parameters used in S102, for example, the maximum response duration Tbd among the response times when the digital binarized signal DGs falls and the predetermined frequency component of the digital waveform signal DGw are extracted. Then, the converted secondary digital waveform signal DGb (see FIG. 11B) is analyzed, and the subtraction waveform value Bvp obtained by subtracting the maximum value and the minimum value of the secondary digital waveform signal DGb is used as a response. A new state parameter (Tbd / Bvp) obtained by dividing the sustained maximum time Tbd by the subtracted waveform value Bvp may be used. At this time, the state threshold value Pd used in S102 needs to be appropriately changed according to the new state parameter (Tbd / Bvp). Here, the secondary digital waveform signal DGb will be described with reference to FIG. In FIG. 11A, a noise waveform in a misfire state is schematically shown as an example. When the digital waveform signal DGw or the analog waveform signal AGw is in a misfire state, a phenomenon such as a discharge in the spark plug PG is expressed, whereby a predetermined noise waveform δ can be superimposed. At this time, in order to analyze individual noise, a technique for extracting a frequency specific to each noise waveform is known. Such a method is realized by filtering a predetermined noise waveform using a BPF (Band Pass Filter). FIG. 11B shows a waveform in which the noise waveform is filtered by the BPF. In addition, when performing filtering by BPF, a parameter calculation range Winq (second parameter calculation range in claim 5) is newly provided, and a predetermined noise waveform is extracted within the parameter calculation range Winq. Therefore, based on the noise waveform δ ′ extracted as described above, the maximum value and the minimum value of the noise waveform are subtracted to calculate a subtracted waveform value Bvp. As a result, a new state parameter Tbd / Bvp is calculated based on the time parameter (maximum response duration Tbd) calculated as described above and the waveform parameter composed of the subtraction waveform value Bvp, and the state parameter Tbd / Bvp is , Used when performing misfire determination in S102.

Further, as other parameters used in S102, for example, the maximum response duration Tbd among the response times when the digital binarized signal DGs falls and the predetermined frequency component of the digital waveform signal DGw are extracted. An integrated waveform value Bin consisting of a sum of values obtained by analyzing the converted secondary digital waveform signal DGb (see FIG. 11b) and integrating the area defined by the secondary digital waveform signal DGb and the reference time axis CL. And a new parameter (Tbd / Bin) obtained by dividing the maximum response duration Tbd by the integrated waveform value Bin may be used. Here, the integrated waveform value Bin will be described with reference to FIG. This figure shows a partially enlarged view of the waveform DGb after filtering in FIG. As shown in the figure, when the area surrounded by the secondary digital waveform signal DGb and the reference time axis CL is Sm, the integrated waveform value Bin is the total area Sm (1 ≦ m ≦ n) existing in the parameter calculation range Winq. ). Thus, the other state parameter Tbd / Bin is calculated based on the time parameter (maximum response duration time Tbd) calculated as described above and the waveform parameter composed of the integrated waveform value Bin, and the state parameter Tbd / Bin is , Used when performing misfire determination in S102.

Further, as other state parameters used in S102, for example, the maximum response duration Tbd among the response times when the digital binarized signal DGs falls and the predetermined frequency component of the digital waveform signal DGw are extracted. Using the differential waveform value Bca obtained by analyzing the converted secondary digital waveform signal DGb (see FIG. 11b) and calculating the frequency of the secondary digital signal DGb, the response duration maximum time Tbd is determined as the differential waveform value Bca. Other state parameters (Tbd / Bca) obtained by dividing by may be used. Here, the differential waveform value Bca will be described with reference to FIG. As shown in the figure, the differential coefficient of the waveform of the secondary digital signal DGb is calculated, and the number n of differential coefficients En for which the differential value is zero is counted. Thereby, the frequency of the secondary digital signal DGb within the parameter calculation range Winq is calculated, and the differential waveform value Bca is obtained. However, another state parameter Tbd / Bca is calculated based on the time parameter calculated as described above (maximum response duration Tbd) and the waveform parameter composed of the differential waveform value Bca, and the state parameter Tbd / Bca is It is used when performing misfire determination in S102.

According to the ignition device 1 for an internal combustion engine according to the present embodiment, by generating a plurality of parameters based on the analog waveform signal AGw input to the ECU 40 and using the state parameter Ps determined by the time parameter Pt and the waveform parameter Pw, Since complicated fluctuations in the digital binarized signal DGs can be analyzed appropriately, the discrimination accuracy between the combustion state and the misfire state is improved even when corona noise occurs. Further, the deviation Dv is calculated based on the analog waveform signal AGw input to the ECU 40, and the generation of residual noise at the end of discharge is made effective by comparing the value of the deviation Dv in the combustion state and the misfire state and the distribution state of the deviation Dv. In addition to detection, corona noise can also be detected, and the discrimination accuracy between the combustion state and the misfire state can be improved. Further, when such a determination is made, various threshold values defined based on the operation state signal QG determined by the intake pressure of the internal combustion engine and the rotational speed of the crankshaft are appropriately used, so that the drive state of the internal combustion engine is followed. Thus, the threshold value setting is realized, thereby improving the accuracy of misfire determination.

According to the misfire detection method for the internal combustion engine according to the present embodiment, the misidentification of misfire detection is eliminated without omission by combining the discrimination process using the state parameter Ps and the discrimination process using the deviation Dv. Thus, it is possible to improve the S / N ratio related to the combustion determination signal generated in the combustion determination unit 40e.

The embodiment described as above is merely one embodiment of the present invention, and the meaning of the present invention or the terms of each constituent element is not limited to those described in the above embodiment. . For example, in the ignition device 1 according to the present embodiment, the configuration of the calculation unit in the ECU 40 is described as including both the parameter calculation unit 40c and the deviation processing unit 40d, but the configuration is limited to this configuration. Instead, the calculation unit in the ECU 40 may alternatively include only one of the parameter calculation unit 40c and the deviation processing unit 40d. Further, in the misfire detection method according to the present embodiment, the logical determination based on the parameter (Tbt> Mis) is adopted in the initial step (S101) of the determination routine for performing the misfire / combustion determination. Such logical judgment should be adopted as appropriate by adapting other parameters to predetermined conditions. Further, in the misfire detection method, other determination processes related to the determination routine may be added to and changed at appropriate positions, and the processing order of the parameter determination process / upper limit deviation determination process / lower limit deviation determination process may be changed as appropriate. Also good.

The figure which shows the circuit structure of the ignition device which concerns on embodiment The figure which shows the structure of the calculating part in ECU which concerns on embodiment The figure which shows each waveform based on the ion current which concerns on embodiment The figure which shows each waveform based on the ion current which concerns on embodiment The figure which shows each waveform based on the ion current which concerns on embodiment The figure which shows the deviation which concerns on embodiment, and its process The figure which shows the deviation which concerns on embodiment, and its process The figure which shows the deviation which concerns on embodiment, and its process The figure which shows the relationship between the continuous frequency and occurrence frequency which concern on embodiment The flowchart which shows an example of the algorithm of misfire determination which concerns on embodiment The figure which shows the normal ion waveform which concerns on embodiment, and the ion waveform after filtering

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ignition device 10 Ignition coil PG Spark plug Vcc Battery 20 Switching element SG Ignition pulse signal 30 Ion current detection circuit 35 Gain resistor 40 ECU (control circuit)
AGw Analog waveform signal AGs Analog binarized signal DGw Digital waveform signal DGs Digital binarized signal 41a A / D converter Tc A / D timing 41b Parameter calculator Pt Time parameter Mis Near ignition time Tbd Maximum response duration Tbi Total response Time Tbt Combustion possibility time Pw Waveform parameter Cca Number of responses DGb Secondary digital waveform signal Bvp Subtraction waveform value CL Reference time axis Bin Integral waveform value Bca Differential waveform value Ps State parameter 41c Observation interval calculation unit Winp First parameter calculation range Winq 1st Two-parameter calculation range Wind Deviation processing range 41d Deviation processing unit Dv Deviation 41e Combustion discrimination unit Pd State threshold Vsu Upper limit deviation threshold Vsl Lower limit deviation threshold Nc Continuous count Ncd Continuous threshold count Nn Upper limit deviation excess count Nnd Threshold count Nm ax Minimum value of noise frequency range Nmin Maximum value of combustion frequency range

Claims (18)

An ignition coil that supplies a high voltage to the spark plug, a switching element that intermittently switches the driving state of the ignition coil based on an ignition pulse signal, and an ion current that converts an ion current discharged from the spark plug into an analog waveform signal A detection circuit; and a control circuit that generates the ignition pulse signal based on the analog waveform signal;
The control circuit includes:
An observation interval calculation unit for calculating a parameter calculation range based on an operation state signal determined by an intake pressure of an internal combustion engine and a crankshaft rotation speed, a digital waveform signal and a digital binary signal by processing the analog waveform signal at each A / D timing An internal combustion engine comprising: an A / D conversion unit that generates a digitized signal; a parameter calculation unit that calculates a plurality of parameters; and a combustion determination unit that determines combustion or misfire based on the plurality of parameters. Engine ignition device. An ignition coil that supplies a high voltage to the spark plug, a switching element that intermittently switches the driving state of the ignition coil based on an ignition pulse signal, and an ion current that converts an ion current discharged from the spark plug into an analog waveform signal A detection circuit; and a control circuit that generates the ignition pulse signal based on the analog waveform signal;
The control circuit includes:
An observation interval calculation unit for calculating a deviation processing range based on an operation state signal determined by an intake pressure of an internal combustion engine and a rotational speed of a crankshaft, and processing the analog waveform signal at each A / D timing to perform a digital waveform signal and a digital two An ignition device for an internal combustion engine, comprising: an A / D conversion unit that generates a digitized signal; a deviation processing unit that calculates a deviation; and a combustion determination unit that determines combustion or misfire based on the deviation. . An ignition coil that supplies a high voltage to the spark plug, a switching element that intermittently switches the driving state of the ignition coil based on an ignition pulse signal, and an ion current that converts an ion current discharged from the spark plug into an analog waveform signal A detection circuit; and a control circuit that generates the ignition pulse signal based on the analog waveform signal;
The control circuit includes:
An observation interval calculation unit for calculating a parameter calculation range and a deviation processing range based on an operation state signal determined by an intake pressure of an internal combustion engine and a rotation speed of a crankshaft, and digitally processing the analog waveform signal at each A / D timing An A / D conversion unit that generates a waveform signal and a digital binarized signal, a parameter calculation unit that calculates a plurality of parameters, a deviation processing unit that calculates a deviation, and combustion based on the plurality of parameters and the deviation An ignition device for an internal combustion engine, comprising: a combustion determination unit that determines misfire. The A / D converter is
4. The digital binarization signal is generated by setting a predetermined threshold based on the operation state signal and performing a comparison process between the analog waveform signal AGw and the predetermined threshold. Ignition device for internal combustion engine. The parameter calculation range is
The start point is provided at the falling position of the ignition pulse signal, the end point is provided in the first parameter calculation range provided at the position where the ion current during combustion is sufficiently converged, and / or the start point is provided after the discharge end noise generation region. The ignition device for an internal combustion engine according to claim 1 or 3, wherein the ignition point of the internal combustion engine is provided at a position where the end point is provided at a position where the ion current during combustion is sufficiently converged. The plurality of parameters are:
Calculated for the first parameter calculation range,
6. The ignition of the internal combustion engine according to claim 5, comprising a time parameter and a waveform parameter calculated based on the digital binarized signal, and a state parameter obtained by dividing the time parameter by the waveform parameter. apparatus. The plurality of parameters are:
A time parameter calculated for the first parameter calculation range and calculated based on the digital binarized signal, and a digital waveform signal or the analog waveform signal calculated for the second parameter calculation range 6. A waveform parameter calculated based on a secondary digital waveform signal obtained by extracting and converting a predetermined frequency component, and a state parameter obtained by dividing the time parameter by the waveform parameter. An ignition device for an internal combustion engine according to 1. The time parameter is
The maximum response duration of the response time that is the fall time of the digital binarization signal,
The waveform parameter is:
7. The ignition device for an internal combustion engine according to claim 6, wherein the number of times of falling of the digital binarization signal is counted as a response number. The time parameter is
The total response time obtained by integrating the response time that is the fall time of the digital binarization signal,
The waveform parameter is:
7. The ignition device for an internal combustion engine according to claim 6, wherein the number of times of falling of the digital binarization signal is counted as a response number. The time parameter is
The maximum response duration of the response time that is the fall time of the digital binarization signal,
The waveform parameter is:
The internal combustion engine ignition according to claim 7, wherein the secondary digital waveform signal is used as a subtracted waveform value obtained by subtracting a maximum value and a minimum value of the secondary digital waveform signal. apparatus. The time parameter is
The maximum response duration of the response time that is the fall time of the digital binarization signal,
The waveform parameter is:
8. The integrated waveform value comprising a sum of values obtained by integrating the area determined by the secondary digital waveform signal and a reference time axis using the secondary digital waveform signal. An ignition device for an internal combustion engine as described. The time parameter is
The maximum response duration of the response time that is the fall time of the digital binarization signal,
The waveform parameter is:
8. The ignition device for an internal combustion engine according to claim 7, wherein the secondary digital waveform signal is used as a differential waveform value obtained by calculating a frequency of the secondary digital waveform signal. The deviation processing range is
The ignition device for an internal combustion engine according to claim 2 or 3, wherein the start point is provided after the discharge end noise generation region, and the end point is provided at a position where the ion current during combustion is sufficiently converged. . The deviation is
A first digital signal value calculated in the deviation processing range and corresponding to each A / D timing, and a second digital signal value adjacent to the first digital signal value in the digital waveform signal, The ignition device for an internal combustion engine according to claim 2, 3 or 13, wherein the absolute value is a value obtained by subtracting. The combustion determination unit
Comparing the state parameter with a state threshold that is a value set based on the operation state signal and defined by a predetermined value of the state parameter;
13. The internal combustion engine according to claim 6, wherein when the state parameter exceeds the state threshold value, it is determined as a combustion state, and when the state parameter is lower than the state threshold value, it is determined as a misfire state. Ignition device. The combustion determination unit
An upper limit obtained by comparing the deviation with an upper limit deviation threshold value that is set based on the operation state signal and is defined as the predetermined value of the deviation, and counting a deviation of the deviation that exceeds the upper limit deviation threshold value. Get the number of deviations over time,
The upper limit deviation exceeded number is compared with a threshold number that is a value set based on the operation state signal and is defined as a predetermined value of the upper limit deviation exceeded number. 15. If any of the above is exceeded, a misfire condition is determined, and if the upper limit deviation excess count is less than the threshold count, the combustion condition is determined. An ignition device for an internal combustion engine according to 1. The combustion determination unit
The deviation is compared with a lower limit deviation threshold value that is set based on the operation state signal and is defined as the predetermined value of the deviation, and the lower limit deviation is exceeded after the deviation exceeds the lower limit deviation threshold value. Get the number of consecutive times counting deviations distributed before falling below the threshold,
Comparing the number of continuous times with a continuous threshold number that is a value set based on the operating state signal and defined as a predetermined value of the continuous number of times, and combustion when the continuous number of times exceeds the continuous threshold number of times Determining the state, determining the misfire state when the number of consecutive times is less than the number of consecutive thresholds,
The continuous threshold number of times is
The number of continuous times is larger than the maximum value of the noise frequency range in which the continuous number of times in the misfire state with discharge end residual noise or corona noise is distributed, and smaller than the minimum value of the combustion frequency range in which the lower limit number of continuous times is distributed in the combustion state. The ignition device for an internal combustion engine according to any one of claims 2 to 3, or 13 to 16, wherein the ignition device is set within a certain range. The internal combustion engine ignition device according to any one of claims 15 to 17,
A parameter determination step of determining a combustion state when the state parameter exceeds the state threshold, and determining a misfire state when the state parameter is lower than the state threshold;
An upper limit deviation determination step of determining a misfire state when the upper limit deviation excess number exceeds the threshold number, and determining a combustion state when the upper limit deviation excess number is less than the threshold number;
A lower limit deviation determining step for determining a combustion state when the continuous number exceeds the continuous threshold number, and determining a misfire state when the continuous number is less than the continuous threshold number. Misfire detection method.

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