JP2015057546A - Knocking determination device using ion current, and combustion state determination device utilizing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that knocking occurrence cannot be discriminated from noise generation when impulsive noise such as randomly generated corona noise is superposed on an ion current waveform.SOLUTION: A combustion state determination device for determining a combustion state by using an ion current, includes: an ion current detection part which detects an ion current generated between ignition plugs as a result of combustion of an internal combustion engine; and a determination part which detects the combustion state of the internal combustion engine based on an ion current detected by the ion current detection part. The combustion state determination device further includes: noise extraction means for performing BPF processing reacting on a high frequency, on the ion current from the ion current detection part; median processing means for outputting a center value from data acquired at desired time intervals before and after the high frequency as to the ion current after the BPF processing; and correction means for correcting the ion current according to an output of the median processing means.

Description

The present invention relates to an apparatus for determining a combustion state using an ionic current generated between electrodes of a spark plug by combustion of an internal combustion engine, and particularly, eliminates the influence of impulsive noise such as corona noise and is generated during combustion of the internal combustion engine. The present invention relates to a combustion state determination device that detects knocking.

Conventionally, knocking of an internal combustion engine causes an abnormal state in which an explosion generated by spontaneous ignition of an air-fuel mixture overlaps with an explosion generated by ignition of a spark plug and generates a shock wave. When such an abnormal state occurs, the internal combustion engine will be damaged. Therefore, it is necessary to detect and suppress knocking occurring in the internal combustion engine, and detect the occurrence of knocking from the ionic current generated during combustion of the internal combustion engine. It is known. For example, Japanese Patent Laid-Open No. 6-159129 (hereinafter “Patent Document 1”) has been proposed.

In Patent Document 1, an ionic current detected when detecting knock is generated by applying a bias voltage from a bias power source to a spark plug immediately after ignition, decreases before top dead center, increases again, and combustion pressure increases. In the vicinity of the maximum crank angle, the value is maximized. In such an ionic current having a low frequency frequency characteristic, the detected ionic current has a step-like change current Is that instantaneously increases even in a normal state where no knock occurs. Exists. This step-like change current has a high-frequency characteristic equivalent to a knock current, and exists only once in one ion current. In contrast to such changes, a knock current having a high frequency characteristic that is superimposed on an ionic current when a knock occurs is a continuous change, and a knock detection method that can be distinguished by integration is described. ing.

As another example, Japanese Patent Laid-Open No. 10-89216 (hereinafter “Patent Document 2”) has been proposed. In Patent Document 2, a voltage is applied to a pair of electrodes installed in a combustion chamber of an internal combustion engine, and knocking is performed based on an ionic current flowing between the pair of electrodes via ions generated when an air-fuel mixture in the combustion chamber burns. Whether or not knocking has occurred based on the vibration of the cylinder block detected by the first knocking occurrence determining means for determining whether or not the engine has occurred and the knock vibration sensor installed in the cylinder block of the internal combustion engine. When it is determined that knocking has occurred in both the second knocking occurrence determining means and the first knocking occurrence determining means and the second knocking occurrence determining means, the ignition timing is retarded to control the first knocking. Ignition when it is determined that knocking has occurred in at least one of the occurrence determination means or the second knock occurrence determination means Knock control apparatus comprising an ignition timing control means for inhibiting retarding control period, a is described.

As another example, Japanese Patent Laid-Open No. 10-103210 (hereinafter “Patent Document 3”) has been proposed. An ion current detecting means for applying a voltage to a pair of electrodes installed in a combustion chamber of an internal combustion engine and detecting an ion current flowing between the pair of electrodes through ions generated when the air-fuel mixture in the combustion chamber burns; A knocking frequency component extracting means for extracting a knocking frequency component representing the occurrence of knocking from the output signal of the ion current detecting means, and whether or not the knocking frequency component extracted by the knocking frequency component extracting means is equal to or greater than a threshold value. The knocking occurrence determining means for determining whether knocking has occurred or not by determining, the combustion degree detecting means for detecting the degree of combustion stability in the cylinder of the internal combustion engine, and the combustion stability degree detected by the combustion degree detecting means And a threshold value changing means for changing the threshold value used in the knocking occurrence determining means in response to the knocking. Detector is described.

JP-A-6-159129 JP-A-10-89216 JP-A-10-103210

However, the conventional knocking detection apparatus has the following problems. That is, in Patent Documents 1 to 3, when noise emitted from an electrical device such as an alternator is superimposed on an ionic current waveform, an erroneous determination that knocking of the noise waveform has occurred can be avoided. There arises a problem that it is impossible to distinguish between noise generation and knock generation when impulsive noise such as generated corona noise is superimposed on the ion current waveform.

The present invention has been made in view of the above problems, and provides a combustion state determination device that reliably detects knocking even when impulsive noise such as corona noise that occurs irregularly is superimposed on the ion current waveform. Goal.

In order to solve the above problems, the present invention has the following configuration. That is, a coil unit having a primary coil and a secondary coil, a switching element that controls energization to the primary coil, a control unit that supplies an ignition signal composed of a pulse wave to the switching element, and the secondary An ignition plug that discharges a high voltage generated from the induced electromotive force of the coil, an ion current detection unit that detects an ion current generated between the electrodes of the ignition plug due to combustion of the internal combustion engine, and an ion current from the ion current detection unit A determination unit for determining the combustion state of the internal combustion engine, and a combustion state determination device using an ionic current, the noise extraction means for executing a BPF process that reacts to a high frequency with respect to the ionic current from the ionic current detection unit; For the ion current after the BPF treatment, a median value is output from data acquired at desired time intervals before and after the high frequency. That to the median processing means, and correcting means for correcting the ionic current from the output from the median processing means, and the combustion state determining device using the ion current, characterized in that it comprises a.

The above invention comprises a knock BPF that detects a knock component from the ion current corrected by the correction means, and a noise BPF that detects a noise component from the ion current corrected by the correction means, and at least the median processing means The knocking may be determined from the knock component detected by the knock BPF except the section in which data at a desired time interval is acquired and the subtraction result of the noise component detected by the noise BPF.

According to said structure, the coil part which has a primary coil and a secondary coil, the switching element which controls electricity supply to the said primary coil, and the control part which supplies the ignition signal which consists of a pulse wave to the said switching element An ignition plug that discharges a high voltage generated from the induced electromotive force of the secondary coil, an ion current detection unit that detects an ion current generated between electrodes of the ignition plug due to combustion of an internal combustion engine, and the ion current detection unit And a determination unit for determining a combustion state of the internal combustion engine from an ion current from a combustion state determination apparatus using an ion current, wherein the ion current from the ion current detection unit performs a BPF process that reacts to a high frequency The noise extraction means and the ionic current after the BPF processing are data acquired at desired time intervals before and after the high frequency. By providing a median processing means for outputting a median value and a correction means for correcting the ionic current from the output from the median processing means, impulsive noise such as irregular corona noise is generated in the ionic current waveform. Even if they are superposed, a combustion state determination device that reliably detects knocking can be realized.

A knock BPF for detecting a knock component from the ion current corrected by the correction means; and a noise BPF for detecting a noise component from the ion current corrected by the correction means, and at least a desired time by the median processing means. By adopting a configuration in which knocking is determined from the knock component detected by the knock BPF other than the interval in which the interval data is acquired and the subtraction result of the noise component detected by the noise BPF, correction is performed when corona noise is removed. Can be prevented from being influenced by knock determination.

1 is a block diagram of an ignition device according to a first embodiment of the present invention. It is the time chart which showed the ion current waveform (a) with which the corona noise was superimposed, and the ion current waveform (b) after a median process about the ion current with which the corona noise was superimposed. It is a BPF waveform of the ionic current on which corona noise is superimposed. The ion current waveform (a) at the time of sampling, the median processing diagram (b) of the ion current waveform, and the ion current waveform (c) after the median processing for the ion current on which corona noise is superimposed. It is the time chart which showed the ion current waveform (a) on which the corona noise and the knock component were superimposed, and the ion current waveform (b) after the median processing for the ion current on which the corona noise and the knock component were superimposed. It is a BPF waveform of an ion current in which corona noise and a knock component are superimposed. The ion current waveform (a) at the time of sampling, the median processing diagram (b) of the ion current waveform, and the ion current waveform (c) after the median processing for the ion current on which the corona noise and the knock component are superimposed. 3 is a flowchart showing the operation of the combustion state determination device according to the first embodiment. 4 is a time chart showing a knock BPF waveform (a), a noise BPF waveform (b), and a knock BPF waveform-noise BPF waveform (c).

In the following, examples showing embodiments of the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram of an ignition device according to a first embodiment of the present invention. FIG. 1 shows an ion current waveform (a) in which corona noise is superimposed and an ion current waveform after median processing ( 2 is a time chart showing b), a BPF waveform of an ion current superimposed with corona noise in FIG. 3, and an ion current waveform (a) at the time of sampling and an ion current waveform for the ion current superimposed with corona noise. Fig. 4 shows the median processing diagram (b) and the ion current waveform (c) after the median processing. Fig. 4 shows the ion current waveform (a) in which the corona noise and the knock component are superimposed on the ion current in which the corona noise and the knock component are superimposed. FIG. 5 is a time chart showing the ion current waveform (b) after the median treatment. The BPF waveform of the current is shown in FIG. 6, and the ion current waveform (a) during sampling, the ion current waveform median processing diagram (b), and the ion current waveform after median processing for the ion current with the corona noise and knock component superimposed. FIG. 7 is a flowchart illustrating the operation of the combustion state determination device, and FIG. 8 is a knock BPF waveform (a), a noise BPF waveform (b), and a knock BPF waveform-noise BPF waveform (c). The time chart is shown in FIG.

In FIG. 1, an ignition device 100 includes an ECU (Engine Control Unit) 10 that performs electronic control of an internal combustion engine, a coil portion Co that includes a primary coil 20 and a secondary coil 30, and a pulse wave that is received from the control portion of the ECU 10. A switching element 40 for performing ON / OFF control of the current of the primary coil 20 based on an ignition signal comprising: an ignition plug 50 for discharging a high voltage generated from the induced electromotive force of the secondary coil 30; and an ion current detection Part Ion.

Further, the output voltage of the ion current detector Ion is supplied to the ECU 10 and stored in the ECU 10 as an ion output signal. Further, the output voltage of the ion current detection unit Ion is acquired in a period from the fall of the pulse wave to the disappearance of the ion current, and the ECU 10 executes the BPF process from all the data acquired at one combustion. The

The switching element 40 is an IGBT (insulated gate bipolar transistor). Further, the collector terminal of the switching element 40 is connected to the battery 60 via the primary coil 10, and the emitter terminal is connected to the ground.

The ion current detector Ion includes an operational amplifier Amp that converts an ion current generated between the electrodes of the spark plug 50 into an output signal, a capacitor C1, a Zener diode ZD, diodes D1 and D2, and resistors R1 and R2. Has been. Further, a bias power supply at the time of ion current detection is generated by the parallel circuit of the capacitor C1 and the Zener diode ZD.

The high voltage terminal of the secondary coil 30 is connected to the spark plug 50, and the low voltage terminal is connected to a parallel circuit of the capacitor C1 and the Zener diode ZD for generating a bias power source. Further, the parallel circuit of the capacitor C1 and the Zener diode ZD is connected to the ground via the diode D1.

The anode terminal of the diode D1 is connected to the inverting input terminal (−) of the operational amplifier Amp via the resistor R1. Further, the resistor Z2 for detection is connected between the inverting input terminal (−) and the output terminal of the operational amplifier Amp. Further, the inverting input terminal (−) of the operational amplifier Amp is connected to the ground via the diode D2, and the non-inverting input terminal is connected to the ground.

In the ignition device 100 described above, when the pulse wave from the ECU 10 falls, the ignition plug 50 is discharged by the high voltage induced in the secondary coil 30. The discharge current at this time flows through the path of the spark plug 50 → the secondary coil 30 → the capacitor C1 → the diode D1, and the capacitor C1 is charged with a bias power supply by the breakdown voltage of the Zener diode ZD. When the combustion due to the discharge from the spark plug 50 ends, the ionic current i generated between the electrodes of the spark plug 50 is the resistance R2 → the resistance R1 → the capacitor C1 → the secondary coil 30 → the ignition. It flows in the path of plug 50.

2A shows an ion current output signal on which corona noise is superimposed, and FIG. 2B shows an ion current output signal after corona noise is removed. In FIG. 2 (a), corona noise is superimposed in regions W, X, and Y, and the corona noise is impulsive noise that occurs irregularly. Further, the ion current output signal output from the ion current detection unit Ion to the ECU 10 rises after the combustion of the internal combustion engine, rises to a peak value, and then ends, and from the waveform of the output signal, the internal combustion engine When determining the combustion state, such corona noise may be erroneously determined as knock.

FIG. 3 shows a waveform after the BPF processing of the output signal waveform shown in FIG. The BPF process is a system provided in the ECU 10, and a high frequency region due to corona noise is extracted by a BPF filter. In addition, the BPF process results in a waveform in which the region W portion, the X portion, and the Y portion shown in FIG. As a result, only the corona noise in the regions W, X, and Y is exposed in the BPF waveform in FIG. 3 with respect to the output signal waveform in which the corona noise in FIG. 2A is superimposed.

4A, the output signal waveform shown in FIG. 2A is a waveform showing sampling centered on the area W shown in FIG. 3, and the protruding portion due to corona noise in the area W is centered. 9 values (time t _{1 to} t ₉ ) are sampled. Further, the ECU10 stores nine points sampled in FIGS. 4 (a) to (time _t 1 ~t ₉₎ as A~I value. Further, FIG. 4B shows a median processing diagram of the ion current waveform, and the ECU 10 performs median processing on the input A to I values and outputs them.

The time t ₁ ~t ₉ of 9 points to be sampled, the be one interval time t ₁ ~t ₉ by the rotation speed of the internal combustion engine is changed, at the time of high rotation of the internal combustion engine, the time t ₁ spacing ~t ₉ is set narrow, during low rotation, it is assumed that the interval of time t ₁ ~t ₉ is set wider.

Also, the median processing arranges the data input from a plurality of points in a descending order, a process to output the median value (the value of the middle position) at time t _5. In FIG. 4A, when the A to I values input to the ECU 10 are arranged in descending order, E value> A value> D value> B value> C value> F value> G value> H value> I value Thus, the median value at time t ₅ ′ is the C value. By the median processing, the A value, B value, C value, D value, C value, F value, G value, H value, and I value are output. Further, FIG. 4C shows a waveform reflecting the median processing performed in FIG. 4B with respect to the output signal waveform of FIG.

FIG. 4C shows the corona noise in the area W shown in FIG. 2B by outputting the C value after median processing in response to the input of the E value in FIG. 4A. An output signal waveform from which is removed is output, and the combustion state of the internal combustion engine is determined. Further, although not shown in the figure, the median process is executed in the areas X and Y in FIG. 2A in the same manner as in FIG. 4B, so that the areas W ′ and X ′ shown in FIG. Signal waveform obtained by removing the corona noise from the Y and Y 'portions. That is, the ECU 10 determines that the combustion of the internal combustion engine is normally performed from the output signal waveform shown in FIG.

5A shows an ion current output signal in which corona noise and knock components are superimposed, and FIG. 5B shows an ion current output signal in which knock components after corona noise removal are superimposed. In FIG. 5A, corona noise is superimposed in the region Z, and a knock component generated when knocking of the internal combustion engine is also superimposed around the corona noise.

6 shows a waveform after the BPF processing of the output signal waveform shown in FIG. By the BPF process, the region Z shown in FIG. 5A has a waveform protruding to a high value. Further, the knock component shown in FIG. 5A does not appear in the high-frequency region of the BPF process because the magnitude of the change with respect to the output signal is not large. That is, the BPF process can extract only the corona noise component as in FIG. 3 even if the corona noise and the knock component are superimposed on the ion current output signal.

7A, the output signal waveform shown in FIG. 5A is a waveform showing sampling centered on the area Z shown in FIG. 6, and the projecting portion due to corona noise in the area Z is centered. 9 values (time t _{1 to} t ₉ ) are sampled. Further, the ECU10 stores nine points sampled in FIGS. 7 (a) to (time _t 1 ~t ₉₎ as J~R value. Further, FIG. 7B shows a median processing diagram of the ion current waveform, and the ECU 10 performs median processing on the input J to R values and outputs them.

7A, when the J to R values input to the ECU 10 are arranged in descending order, N value> J value> L value> K value> M value> O value> Q value> P value> The R value is obtained, and the median value at time t ₅ ′ is the M value. Then, the median process outputs the values as J value, K value, L value, M value, M value, O value, P value, Q value, and R value. Further, FIG. 7C shows a waveform reflecting the result of the median processing performed in FIG. 7B with respect to the output signal waveform in FIG. 7A.

FIG. 7C shows the corona noise in the region Z shown in FIG. 5B by inputting the M value after the median processing in response to the input of the N value in FIG. 7A. The output signal waveform that is only removed is output, and the combustion state of the internal combustion engine is determined from the output signal waveform on which the knock component is superimposed. That is, the ECU 10 determines that knocking has occurred in the combustion of the internal combustion engine from the output signal waveform shown in FIG.

Next, operation | movement of a combustion state determination apparatus is demonstrated based on FIG. The ECU 10 receives an output signal obtained by converting the ion current i generated by the combustion of the internal combustion engine detected by the ion current detector Ion (S1), and the ECU 10 receives the ion current output signal input in S1. On the other hand, the BPF process is executed (S2), and the ECU 10 detects a high-frequency region that has reacted with the BPF waveform of S2 (S3). Further, the ECU 10 samples at nine points centering on the high frequency region detected in S3, and detects the values of nine points of the output signal waveform (S4). Further, the median process is executed for the nine values of the output signal waveform sampled in S4 (S5), and the ECU 10 corrects the ion current output signal of S1 from the result of the median process calculated in S5 (S6). ).

The ECU 10 determines whether there is another high-frequency region of the ion current i from the BPF waveform reacted in S2 (S7), and no other high-frequency region of the ion current i exists from the BPF waveform in S7. The ECU 10 executes knock BPF processing on the ion current output signal corrected in S6, detects a knock waveform from which a knock component has been extracted (S8), and the ECU 10 outputs the ion current output corrected in S6. Noise BPF processing is performed on the signal, and a noise waveform from which a noise component is extracted is detected (S9). Further, the ECU 10 subtracts the knock waveform detected at S8 and the noise waveform detected at S9 excluding the section where the output signal waveform is sampled at S4 (S10), and the ECU 10 calculates the waveform calculated at S10. To determine whether or not knocking occurs in the combustion of the internal combustion engine (S11).

When it is determined in S7 that there are other high-frequency regions of the ion current i from the BPF waveform, the ECU 10 samples at nine points centering on the second high-frequency region, and the value of the nine points of the output signal waveform Is detected (S4). In this case, all of the corona noise superimposed on the ion current output signal can be removed by repeatedly executing the processing from S4 to S6.

Incidentally, the ECU 10 includes a determination unit that determines the occurrence of knock in the combustion of the internal combustion engine, a noise extraction unit 12 that performs the BPF processing, a median processing unit 14 that performs the median processing, and a result of the median processing. And a correction means 16 for correcting the ion current output signal, and is configured as a knock determination device for the internal combustion engine.

9, (a) is a knock BPF waveform of the ion current output signal corrected by the correcting means 16, (b) is a noise BPF waveform of the ion current output signal corrected by the correcting means 16, and (c) is a knock BPF. The waveform which subtracted the noise BPF waveform from the waveform is shown. In FIG. 9 (a), the knock BPF detects a frequency region that becomes a knock component. Of the ion current output signal, the median processing section in which the corona noise corrected by the median processing is superimposed is a knock component. Is detected with a small waveform. In FIG. 9B, the noise BPF detects a frequency region that is a noise component of the ion current output signal. Further, in FIG. 9C, the B section as the median processing section shown in FIG. 9B is excluded from the knock BPF waveforms in the A and C sections excluding the B section as the median processing section shown in FIG. 9A. A waveform obtained by subtracting the noise BPF waveform in the A and C sections is calculated. This is because, in the B section shown in FIG. 9 (a), the output signal waveform becomes flat by median processing, and the knock component is reduced. Therefore, it is difficult to calculate an accurate knock intensity when the noise component is subtracted. To prevent this.

Further, the ECU 10 determines the presence / absence and intensity of knocking of the internal combustion engine based on an integral value calculated from a cumulative value on the time axis of the waveform shown in FIG. 9C.

With the above configuration, the BPF process is executed on the ion current output signal detected from the combustion of the internal combustion engine, and the median process is executed with nine values sampled around the high frequency region detected by the BPF process. By correcting the ion current output signal from the median processing result and making a knock determination, even if impulsive noise such as irregular corona noise is superimposed on the ion current waveform, knocking is reliably detected can do.

In addition, by adopting a configuration in which knocking of the internal combustion engine is detected from a waveform obtained by subtracting the knock BPF waveform and the noise BPF waveform excluding the median processing section, the corrected waveform when the corona noise is removed is affected by the knock determination. Can be prevented.

As a modification of the first embodiment, the circuit configuration of the ion current detection unit Ion is an example, and a circuit configuration other than the above may be used. The ECU 10 includes the noise extraction unit 12 that executes the BPF process, the median processing unit 14 that executes the median process, and a correction unit 16 that corrects an ion current output signal. Although configured as a knock determination device, the noise extraction means 12, the median processing means 14, and the correction means 16 may be provided separately. Furthermore, the median processing may be performed by calculating the median value from values sampled at a plurality of locations around the high frequency region detected by the BPF processing.

Further, the presence / absence and intensity of knocking of the internal combustion engine are determined from the area of the waveform obtained by subtracting the noise BPF waveform from the knock BPF waveform, but the method of determining knocking of the internal combustion engine is not limited to the above. Furthermore, although the combustion state determination device is a device that determines knocking of the internal combustion engine, the combustion state determination device may be a device that determines other combustion states such as misfire from the ion current output signal waveform corrected by the median processing.

10: ECU
12: Noise extraction means
14: Median processing means
16: Correction method
20: Primary coil
30: Secondary coil
40: Switching element
50: Spark plug
60: Battery
100: Ignition device Co: Coil part Ion: Ion current detection part C1: Capacitor ZD: Zener diode D1, D2: Diode Amp: operational amplifier R1, R2: resistance

Claims (2)

A coil portion having a primary coil and a secondary coil;
A switching element for controlling energization to the primary coil;
A controller for supplying an ignition signal comprising a pulse wave to the switching element;
A spark plug for discharging a high voltage generated from the induced electromotive force of the secondary coil;
An ion current detector that detects an ion current generated between the electrodes of the spark plug by combustion of the internal combustion engine;
In a combustion state determination device using an ion current, comprising: a determination unit that determines a combustion state of the internal combustion engine from an ion current from the ion current detection unit,
Noise extraction means for executing a BPF process that reacts to a high frequency with respect to the ion current from the ion current detection unit;
Median processing means for outputting a median value from data acquired at desired time intervals before and after the high frequency for the ionic current after the BPF processing,
And a correction unit that corrects the ion current from the output from the median processing unit. A knock BPF for detecting a knock component from the ion current corrected by the correcting means;
A noise BPF for detecting a noise component from the ion current corrected by the correction means,
The knocking is determined from a knock component detected by the knock BPF except a section where data of a desired time interval is acquired by at least the median processing means and a subtraction result of the noise component detected by the noise BPF. A knock determination device using the ion current according to Item 1.

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