JPH11295188A - Control signal processing system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately determine various kinds of control signals, which are observed in an ionic current, for an internal combustion engine without being affected by a noise component or the like from the outside. SOLUTION: DFT frequency analysis is conducted by a processing part 44 in a DSP 40 of an ECU 20, using an ADD-converted value ADD-converted by an A/D converter 42 after extracting a prescribed frequency component, e.g. a knocking detecting signal, contained in #1-#4 ionic currents flowing between an ignition plug and a gland by an LPF 27, an HPE 28 or the like. Knocking determination is carried out based on a result by the frequency analysis to determine an operation condition of an internal combustion engine. That is, since a feature, for example generation of a noise or superposition of a noise, is observed remarkably in the result of the frequency analysis in the frequency analysis after the prescribed frequency component contained #1-#4 ionic currents is A/D-converted to be digitalized, the operation condition of the internal combustion engine is accurately determined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control signal processing system for an internal combustion engine that performs signal processing for various controls using an ionic current generated in a combustion chamber of the internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as a prior art document related to a control signal processing system for an internal combustion engine, there is Japanese Patent Laid-Open No. 6-1591.
One disclosed in Japanese Patent Publication No. 29 is known. In this technology, similar to signal processing using a well-known vibration type knock sensor, a knock determination technique based on a result obtained by separating and integrating a knock current having a specific frequency characteristic from an ion current generated in an internal combustion engine by an analog circuit is disclosed. It is shown.

[0003]

By the way, the amplitude of the knock signal appearing in the ion current is small depending on the operation state, and an external signal such as that generated at the time of passing (passing) or phone (horn) the ion current. If the noise component from the signal is superimposed, it is difficult to make an accurate knock determination using an analog circuit.

Therefore, the present invention has been made to solve such a problem, and various kinds of control signals for an internal combustion engine appearing in an ion current are accurately determined without being affected by external noise components. It is an object of the present invention to provide a control signal processing system for an internal combustion engine that can perform the control signal processing.

[0005]

According to the control signal processing system for an internal combustion engine of the present invention, the predetermined frequency component contained in the ionic current flowing between the ignition plug and the ground detected by the ionic current detecting means. Is extracted by the frequency component extracting means and A / D converted by the arithmetic processing means.
Frequency analysis is performed using the converted value, and the operation state of the internal combustion engine is determined based on the result. That is, in the frequency analysis after the predetermined frequency component included in the ion current is A / D converted and digitized, for example, the characteristic of occurrence of knock or superposition of noise appears remarkably in the frequency analysis result. Therefore, the operating state of the internal combustion engine can be accurately determined.

In the control signal processing system for an internal combustion engine according to the present invention, a DSP as a CPU capable of high-speed multiplication / addition processing is used to perform frequency analysis using an A / D conversion value by an arithmetic processing means. Calculation processing can be performed each time an A / D converted value is taken or immediately after all A / D converted values are taken.

In the control signal processing system for an internal combustion engine according to the third aspect, the arithmetic processing means calculates the spectrum intensity at a predetermined frequency component by the Fourier transform of the A / D conversion value. The spectrum intensity at a frequency and the spectrum intensity at a frequency near the frequency are obtained, and the transition state of the spectrum intensity corresponding to the frequency can be found.

According to the control signal processing system for an internal combustion engine of the fourth aspect, according to the DFT algorithm by the arithmetic processing means, the A / D conversion value is obtained in a predetermined gate section for taking in the A / D conversion value. Fourier transform can be performed for each capture, that is, a Fourier transform can be performed using the capture interval of the A / D converted value, and immediately after the end of the gate section, for example, a knock determination process can be performed using the result of the DFT calculation. Becomes For this reason, the processing time in the knock determination processing and the like can be significantly reduced.

In the control signal processing system for an internal combustion engine according to the fifth aspect, according to the FFT algorithm by the arithmetic processing means, all the A / D conversions are performed in a gate section for taking in an A / D conversion value set in advance. A value is taken in, and immediately after the end of the gate section, an FFT operation is performed as a Fourier transform, and for example, a knock determination process can be performed using the result of the FFT operation. Therefore, the reliability in knock determination processing and the like is improved.

In the control signal processing system for an internal combustion engine according to the sixth aspect, the knocking can be determined by calculating the spectrum intensity at a predetermined frequency component by the arithmetic processing means, as in the third aspect.

In the control signal processing system for an internal combustion engine according to the present invention, since there are a plurality of frequency components, the spectrum intensity at the knock center frequency and the spectrum intensity at frequencies near the knock frequency are obtained by the knock detection processing, and correspond to the frequencies. The transition state of the spectrum intensity can be understood.

In the control signal processing system for an internal combustion engine according to the present invention, necessary frequency components are transmitted and set for each specification from the outside, so that, for example, a predetermined frequency component corresponding to a four-cylinder or six-cylinder internal combustion engine is provided. Can be obtained arbitrarily, and a DSP or the like as arithmetic processing means can be shared.

According to the control signal processing system for an internal combustion engine of claim 9, the ion current flowing between the ignition plug and the ground detected by the ion current detecting means is A / D converted by the arithmetic processing means, DS using the A / D conversion value
The arithmetic processing is performed at P, and the state of the internal combustion engine is determined by the determination means based on the result. That is, in the arithmetic processing by the DSP after the ion current is A / D converted and digitized, for example, the characteristic of occurrence of knock or superimposition of noise appears remarkably in the arithmetic processing result. The state can be accurately determined.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples.

FIG. 1 is a circuit diagram showing an electrical configuration for detecting an ion current in a control signal processing system for an internal combustion engine according to a first embodiment of the present invention. Since the internal combustion engine (not shown) of this embodiment is composed of four cylinders # 1 to # 4 and has the same configuration of the ignition coil / igniter of each cylinder, the ignition coil / igniter 1 for the # 1 cylinder will be described below. Is described.

In FIG. 1, reference numeral 10 denotes an ignition coil;
10a is a primary winding of the ignition coil 10, and 10b is a secondary winding of the ignition coil 10. Reference numeral 12 denotes a spark plug provided in a combustion chamber of an internal combustion engine (not shown). Ignition coil 10
A switching element (NPN transistor) 11 is connected to the primary winding 10a of the first embodiment. An ECU (Electronic Control Unit: electronic control, which will be described later) for performing, for example, a well-known ignition control for an internal combustion engine, is connected to a base of the switching element 11. When the ignition command signal # 1IGT from the unit 20 is input from the connection terminal 1a and the switching element 11 is turned on, the primary winding 10a of the ignition coil 10 is connected to a + B connected to a battery power supply (not shown). A primary current I1 is supplied from a terminal (connection terminal).

A current path in which the secondary current I2 circulates on the secondary winding 10b side of the ignition coil 10 is formed by the ignition plug 12, the secondary winding 10b of the ignition coil 10, the Zener diode 13 and the Zener diode 14. Have been. Here, the Zener diode 13 has a secondary current I2
This diode is connected in a direction opposite to the direction in which the (secondary circulating current) flows, and is connected in parallel with the diode to charge the capacitor 15 serving as an ion current detection power supply. The Zener diode 14 is connected in the forward direction with respect to the direction in which the secondary current I2 flows, and the ion current detecting resistor 16 is connected in parallel with the Zener diode 14.

At the time of detecting the ion current, as is well known, the ignition plug 1 provided in the combustion chamber in the # 1 cylinder of the internal combustion engine is used.
Immediately after the occurrence of the ignition spark due to 2, the ion current IION flows from the capacitor 15 to the secondary winding 10 b of the ignition coil 10 and the ignition plug 12 in this order. The # 1 ion current amplified by the amplifier 17 based on the ion current IION is input to the ECU 20 via the connection terminal 1b.

FIG. 2 shows an ECU in a control signal processing system for an internal combustion engine according to a first embodiment of the present invention.
FIG. 20 is a block diagram showing a configuration of the embodiment 20. The ignition order in a four-cylinder internal combustion engine is # 1 cylinder → # 3 cylinder → # 4 cylinder → # 2 cylinder. Hereinafter, the knock detection processing will be mainly described among the disconnection detection, knock detection, misfire detection, and pre-ignition (Pre-Ignition: premature ignition; hereinafter, simply referred to as “pre-igne”) detection processing using ion current.

In FIG. 2, # 1 generated for each cylinder
The ion current to the # 4 ion current are supplied to the two MPs via the corresponding buffers 21, 22, 23, and 24 in the ECU 20.
X (Multiplexer) 25,26. The MPXs 25 and 26 switch the # 1 ion current to # 4 ion current, and extract necessary signals for each process.
That is, in the knock detection processing, first, the LPF (Low Pass Fi
lter: a low-pass filter) is used to remove noise components composed of unnecessary high-frequency components from the knock detection signal at the time of knock detection. Next, after a noise component composed of a low frequency is removed through an HPF (High Pass Filter) 28, a knock detection signal is amplified through an AMP (Amplifier) 29. The knock detection signal amplified by the AMP 29 is transmitted to an M in a DSP (Digital Signal Processor) 40 for DFT frequency analysis described later.
The signal is input to the A / D converter 42 via the PX 41. It should be noted that the DSP 40 is a CP that can perform high-speed multiplication / addition processing.
It can be regarded as equivalent to U.

Since the knock signal component superimposed on the ion current is considerably small even when the knock is large as compared with the vibration type knock sensor, the ion current waveform has a high resolution for A / D conversion as it is. An expensive A / D converter is required. That is, A /
If the ion current is amplified as it is using a D converter,
This exceeds the range in which A / D conversion is possible (0 to 5 [V]). To cope with this, in the A / D converter 42 of the present embodiment, only the AC component of, for example, 1 kHz or more is extracted from the ion current signal as a knock signal component by the HPF 28 and then amplified by the AMP 29. The later knock detection signal is input. As a result, it is possible to use the inexpensive A / D converter 42 having a low resolution and not so high cost. Also, in this case, the LPF 27 and the HPF 28 are also used for noise removal and AC component extraction, and need not be specially excellent in characteristics, and are inexpensive and simple in configuration.

In addition, in the disconnection detection processing, the disconnection detection signal from which a noise component composed of unnecessary high frequency is removed via the LPF 27 through the MPX 41 in the DSP 40 as it is, and the A / D converter 42 Is input to In the misfire detection processing, a noise component composed of an unnecessary high frequency is removed through the LPF 27 when the misfire is detected.
The misfire detection signal amplified at 30 is the M
The signal is input to the A / D converter 42 via the PX 41. Then, in the plague detection process, the MPX 26 to the LPF 31
, A noise component composed of unnecessary high frequency is removed at the time of pre-ig detection, and a pre-ig detection signal amplified by the AMP 32 is input to the A / D converter 42 via the MPX 41 in the DSP 40. That is, MPX41 is MPX2
Signals can be switched at timings different from 5 and 26. Further, various sensor signals from a water temperature sensor, an intake pressure sensor, etc. (not shown) of the internal
0 is input to the A / D converter 42 via the MPX 41.

The various signal components pre-processed as described above are A / D-converted by an A / D converter 42 in the DSP 40, and the A / D conversion value for disconnection detection and the A / D conversion value for knock detection are provided. , A / D conversion values for misfire detection, A / D conversion values for plague detection, and other A / D conversion values are stored in the corresponding storage areas of the RAM 43. And DSP4
In the misfire / prague detection process performed by the arithmetic processing unit 44 within 0, a misfire / prague determination is made based on whether the input time of a value larger than a preset value (fixed value) is equal to or longer than a predetermined value, and DMA (Direct) is performed. The data is transferred from the DSP 40 to the host CPU 50 via a Memory Access 45.
Since these misfire / prague detection signals are lower frequency signals than knock detection signals described later, the sampling cycle for A / D conversion may be slower than the sampling cycle of knock detection signals. . The DMA 45 may be an I / O (Input / Output) port.

Here, in order to analyze the frequency of the knock detection signal, it is necessary to perform multiplication / addition processing at high speed.
P40 is used. An A / D converter 42 capable of high-speed processing is used to perform A / D conversion of a plurality of channels for various detections such as knock detection and misfire detection.
In the host CPU 50 in the ECU 20, the DSP
An ignition command signal # 1IGT is supplied to ignition coils / igniters (not shown) of cylinders # 1 to # 4 based on the output value from cylinder 40.
To # 4IGT are output via the output interface 51, and well-known ignition control is performed.

Next, the control signal processing system for an internal combustion engine according to this embodiment is applied to extract a knock detection signal,
A knock detection process for performing a knock determination based on the DFT frequency analysis by the arithmetic processing unit 44 in P40 will be described.

First, the relationship between the frequency and the spectrum intensity of the knock detection signal extracted by applying the control signal processing system for an internal combustion engine according to the present embodiment will be described with reference to FIG.

As shown in FIG. 3, for example, five points at frequencies df [0] to df [4] where DFT operation is performed are DMA4
5 from the host CPU 50 to the DSP 40 side. Note that, for example, the frequency df [0] = 270 is fx
[270] indicates that the data is the 270th data of the DFT frequency analysis result. This frequency df [0] to df
The four points [4] are shown in FIG. 3A when the internal combustion engine to be controlled is an in-line four-cylinder engine, and in FIG.
It is set in advance as shown in FIG. Here, the five points of the frequencies df [0] to df [4] may be transmitted from the host CPU 50 shown in FIG. Thus, the DSP 40 can be commonly used regardless of, for example, the four-cylinder or six-cylinder internal combustion engine. Here, the frequency df [0] is a normal knock center frequency (frequency at which the maximum spectrum intensity is obtained at the time of knocking), and the frequency df [1] is a frequency of the knock center frequency ± α (no knock, large knock, small knock determination). Frequency df [2]
Is the frequency near the knock center frequency (spectral intensity of df [0] <df
The frequency used when the spectrum intensity is [2]), the frequency df [3], and the frequency df [4] are other frequencies for knock noise determination. In this way, the contents of the frequencies df [0] to df [4] for performing the DFT operation are determined in advance, and D
Each spectrum intensity S [0] obtained by FT operation
To S [4], that is, knock determination and noise determination are performed based on each DFT value.

Here, for example, when it is necessary to determine the knock, the noise, and the magnitude of the knock for each cylinder,
Cylinders with good S / N ratio or bad cylinders, cylinders that are easy to detect knock or cylinders that are difficult to detect due to deterioration of the spark plug, etc., can be mixed. Therefore, a storage area is provided in the RAM 43 in correspondence with each learning value. And four cylinders,
By transmitting information such as learning values corresponding to an internal combustion engine including six cylinders and eight cylinders by the DMA 45, the DSP 40
Can be shared. For the same reason, various knock determination coefficients, adaptation constants, ADJ (adaptive) values, and the like are also communicated.

Next, a case in which the control signal processing system for an internal combustion engine according to the present embodiment is applied to extract a knock detection signal and make a knock determination will be described in detail with reference to FIGS. 4, 5 and 6. FIG. Hereinafter, # 1 to # 4 correspond to # 1 to # 4 cylinders, and the # 1 cylinder will be mainly described. Here, FIG. 4 is a time chart showing transition states of various signals, etc., FIG. 5 is an enlarged view showing a relationship between a gate section and a knock detection signal in FIG. 4, and FIG. 6 further shows a knock detection signal in FIG. FIG.

In FIG. 4, the # 1 ion current is
Ignition command signal # 1IGT output from ECU 20 is H
After a pulse waveform is output at the ignition timing from high (high) to low (low), # 1 TDC (Top Dea
If the ignition is normal after d Center (top dead center), the flame spreads into the combustion chamber and a desired waveform appears. Then, a gate section signal as a knock detection A / D conversion value acquisition section is output from the host CPU 50 in accordance with the DFT frequency analysis in the knock detection processing of the arithmetic processing section 44 of the DSP 40. The gate section by this gate section signal is ATDC (After Top Dead Center: after top dead center) 15
° CA (Crank Angle: crank angle) from Low to Hig
h and rise, ATDC60 ° CA ~ ATDC90 ° C
At A, it falls from High to Low. The MPX 25 for disconnection / knock / misfire detection is switched so that this gate section includes a High section and # 1 is selected.
Then, a knock detection signal is obtained by switching the MPX 25 for the # 1 ion current. This gate section is H
The A / D converted values of the knock detection signal are sequentially taken in the high section, and a DFT operation process described later is executed each time. Then, immediately after the gate section changes from High to Low, knock determination processing is executed.

As shown in FIG. 5, the knock detection signal in the gate section is sequentially A / D converted at each A / D conversion timing, for example, AD (0), AD (1),..., AD (140). , A
A / D composed of D (141),..., AD (291), AD (292)
293 conversion values are captured. Here, as shown in FIG. 6, for example, after taking in AD (140) as an A / D conversion value, df [0] operation, df [1] operation,
The df [2] operation, df [3] operation, and df [4] operation are executed. Note that if there is time after the df [4] operation to take in AD (141) as the next A / D conversion value, df [5]
Calculation, df [6] calculation,... And A
DF after taking in AD (141) as / D conversion value
Similarly, as the T operation, df [0] operation, df [1] operation, d
The f [2] operation, the df [3] operation, and the df [4] operation are executed.

Next, the DFT operation on the A / D converted values (AD (0),..., AD (n)) fetched as described above will be specifically described with reference to FIGS. .

According to the determinant shown in FIG. 7, only the frequency fx [k] necessary for knock determination is sequentially subjected to Fourier transform every time an A / D conversion value is taken. Here, fx [k] is the spectral intensity of the frequency determined by k, W _N is a twiddle factor, n is an index indicating the order of A / D conversion value AD (n), where n is 0, 1,. N is the total number of A / D converted values.
The twiddle factor WN is expressed by the following equation (1), and kn =
At N, W _N ^kn makes one round, and thereafter repeats.

[0034]

(Equation 1)

Here, cos (2π
· K · n / N) represents the real part, and jsin (2π · k · n)
/ N) represents an imaginary part. In addition, as shown in FIG.
A table of the in function is stored in a ROM (not shown), and the table data is used in the DFT operation. The cos function is used by shifting the phase data of the sin function by 90 °. In FIG. 8, the sampling start value spST is changed to the sampling end value spEN.
The table data of the sine function when N = 2048 up to D is shown. Here, in the table data of FIG.
For example, to find the coefficient of the imaginary part when k = 2, start
To find the coefficient of the real part, start R
Are used every other place from the place, and two places from the place of start I to find the coefficient of the imaginary part when k = 3, and two places from the place of the start R to find the coefficient of the real part. You can use it for other places.

As described above, when N = 2048,
The DFT calculation value of knock center frequency df [0] is calculated as follows. r-th DFT operation value = (A ² + B
² ) ^1/2 . However, A + jB is represented by the following equation (2).

[0037]

A + jB = ｛W (0) × AD (0)｝ + ｛W (1) × AD (1)｝ + ... + ｛W (a) × AD (a)｝ + ... + {W (2046) × AD (2046)} + {W (2047) × AD (2047)} (2) where W (a) is represented by the following equation (3). Note that 0 ≦
a ≦ 2047, and when the sampling frequency is ft and the knock center frequency df [0], r = df [0] / (ft /
N).

[0038]

W (a) = cos (2π · ra / N) −jsin (2π · ra / N) (3) In the gate section in FIG. 5 described above, AD (0) 〜 AD (2
92) Only 293 A / D converted values are used. That is, since AD (a) satisfying a> 292 is all “0”, W (a) × AD (a) = 0. Therefore, a ≦
Only AD (a) which is 292 need be calculated. And
As shown in FIG. 6, each time one A / D conversion value is taken, DF
Since the T operation is performed, the DF
Knock determination processing using the result of the T operation can be performed. That is, in DFT (discrete Fourier transform), all A / Ds in the gate section are different from FFT (fast Fourier transform).
Since the converted values are temporarily stored in the RAM 43, and it is not necessary to execute the Fourier transform operation using the A / D converted values immediately after the end of the gate section, the knock determination processing is completed immediately after the end of the gate section. The processing time until the process can be greatly reduced.

Next, a flowchart of FIG. 9 showing a procedure of a base control of knock detection in the DSP 40 in the ECU 20 used in the control signal processing system for the internal combustion engine according to the first embodiment of the present invention. It will be described based on. This base control routine is repeatedly executed by the DSP 40 at predetermined time intervals.

In FIG. 9, in step S101, it is determined from the gate section signal from the host CPU 50 whether it is the gate ON timing. Step S10
Wait until the determination condition of 1 is satisfied, that is, during the gate section in which the gate is ON.
At 04, the storage area in the RAM 43 is initialized.
First, in step S102, the real part coefficient spR [N] has an initial value start R, the imaginary part coefficient spI [N] has an initial value start I,
The real part flag flg R [N] is “1”, and the imaginary part flag flg I
[N] is set to “−1” (where N is a value of 0 to 4).

Next, the processing shifts to step S103, where the added value SR [N] of the real part and the added value SI [N] of the imaginary part are both "0".
(Where N is a value of 0 to 4). Next, the process proceeds to step S104, and the counter CNT for counting the number of used A / D converted values is cleared to "0". Next, the processing shifts to step S105, where the DFT operation processing described later is executed, and then shifts to step S106, where the gate OF
It is determined whether it is F timing. Step S106
Is not satisfied, that is, during the gate ON gate section, the flow returns to step S105, and 20 μs
DFT calculation processing by each interrupt is repeatedly executed.

On the other hand, when the determination condition of step S106 is satisfied, that is, immediately after the end of the gate section, the flow shifts to step S107. After the interruption processing in step S105 is ended, the flow shifts to step S108. After a knock determination process described later is performed using the result of the DFT calculation process based on the A / D converted value, the process returns to step S101, and the same process is repeatedly performed.

Next, A in step S105 of FIG.
A description will be given based on the flowchart of FIG. 10 showing the processing procedure of the DFT operation by taking in the / D conversion value. Note that this DFT operation routine is executed by the DSP 4 by an interrupt every 20 μs.
It is repeatedly executed at 0.

In FIG. 10, A /
The D-converted value is read and set as AD.
The total number N of A / D conversion values in the FT operation is cleared to “0”. Next, the process proceeds to step S203, where the real part SR [N] of the current time in the DFT calculation processing is calculated by the following equation (4).

[0045]

## EQU4 ## SR [N] ← flg R [N] × data (spR [N]) × AD + SR [N] (4) Next, the processing shifts to step S204, where the current imaginary part in the DFT operation processing is performed. SI [N] is calculated by the following equation (5).

[0046]

## EQU5 ## SI [N] ← flg I [N] × data (spI [N]) × AD + SI [N] (5) Next, the process proceeds to step S205, where the coefficient spR of the next real part is obtained.
[N] and the address of the imaginary part coefficient spI [N] are calculated by the following equation (6). Here, df [N] is a value shown in FIG. 3, and is a fixed value or a value transmitted from the host CPU 50.

[0047]

[Formula 6] spR [N] ← spR [N] + df [N] spI [N] ← spI [N] + df [N] (6) Next, the processing shifts to step S206, where the real part coefficient spR [N]
Is the sampling end value spE of the table data shown in FIG.
It is determined whether it is ND or more. When the determination condition of step S206 is satisfied, that is, when the coefficient spR [N] of the real part exceeds the sampling end value spEND and exceeds the table data, the process proceeds to step S207, and the coefficient spR [N] of the real part.
Is subtracted from the sampling end value spEND and the coefficient of the real part
spR [N]. Next, the process proceeds to step S208,
When one table data shown in FIG. 8 is used, the flag flg R [N] × (−1) of the real part is set, and the sign is inverted. On the other hand, the determination condition of step S206 is not satisfied,
That is, the real part coefficient spR [N] is equal to the sampling end value spEN.
If the difference is less than D, step S207 and step S207
208 is skipped.

Then, the flow shifts to step S209, where it is determined whether or not the imaginary part coefficient spI [N] is equal to or larger than the sampling end value spEND of the table data shown in FIG. The determination condition of step S209 is satisfied, that is, the imaginary part coefficient spI [N]
If is greater than or equal to the sampling end value spEND and exceeds the table data, the process moves to step S210, where the sampling end value spEND is subtracted from the imaginary part coefficient spI [N] to obtain the imaginary part coefficient spI [N]. Next, step S211
When one table data shown in FIG. 8 is used, the imaginary part flag is flg I [N] × (−1), and the sign is inverted. On the other hand, the determination condition of step S209 is not satisfied, that is, the imaginary part coefficient spI [N] is equal to the sampling end value.
If less than spEND, steps S210 and S211 are skipped.

Next, the processing shifts to step S212, where the DFT
It is determined whether the number of calculation points N is 4 and the five types of DFT calculation processing have been completed. If the determination condition of step S212 is not satisfied, that is, if the number of points N of the DFT calculation is not 4 and the five types of DFT calculation processing have not yet been completed, the process proceeds to step S213, and the number of points N of the DFT calculation becomes “+1”. After the value is incremented, the process returns to step S203, and the same processing as described above is repeatedly performed. Then, the determination condition of step S212 is satisfied, that is, the number of points N of the DFT calculation becomes four and the five types of DFs
Upon completion of the T calculation process, the flow shifts to step S214 where A
After the counter CNT that counts the number of used / D converted values is incremented by "+1", this routine ends.

Next, D in step S108 in FIG.
A description will be given based on a flowchart of FIG. 11 showing a processing procedure of knock determination using an FT calculation processing result. This knock determination routine is executed every time the gate section ends.
It is repeatedly executed at 0.

In FIG. 11, at step S301, the DF
After the point number N of the T operation is cleared to “0”, the process proceeds to step S302, where the absolute value of the real part SR [N] and the imaginary part SI [N] obtained by the DFT operation processing, that is, the DFT value S
[N] is calculated by the following equation (7).

[0052]

S (N) ← ｛(SR [N]) ² + (SI [N]) ² ｝ ^1/2 (7) Next, the process proceeds to step S303, where the number of points N in the DFT operation is calculated. Is 4, and it is determined whether the arithmetic processing of the five types of DFT values S [N] has been completed. The determination condition of step S303 is not satisfied, that is, the number of points N of the DFT calculation is 4
If the calculation processing of the five types of DFT values S [N] has not been completed yet, the flow shifts to step S304, and after the number of points N of the DFT calculation is incremented by "+1", the flow returns to step S302. The process is repeatedly executed.

When the determination condition of step S303 is satisfied, that is, when the number of points N of the DFT calculation becomes 4 and the calculation processing of five types of DFT values S [N] is completed, step S3 is performed.
The process proceeds to 05, where it is determined whether the DFT value S [4] is less than the predetermined value K4. The determination condition of step S305 is satisfied,
That is, when the DFT value S [4] is smaller than the predetermined value K4, the process proceeds to step S306, and it is determined whether the DFT value S [3] is smaller than the predetermined value K3. When the determination condition of step S306 is satisfied, that is, when the DFT value S [3] is smaller than the predetermined value K3, the process proceeds to step S307, and the DFT value S [0] which is the DFT value of the knock center frequency is changed to the DFT value S.
[2] It is determined whether or not it is above. This is a countermeasure in a case where the knock center frequency is shifted due to a variation in a sensor or the like.

When the determination condition of step S307 is satisfied, that is, when the DFT value S [0] is larger than the DFT value S [2], the flow shifts to step S308, where the DFT value S [0] is set to the knock value KNK. On the other hand, the determination condition of step S307 is not satisfied, that is, the DFT value S [0] is changed to the DFT value S [2].
If less than DF, the flow shifts to step S309, where DF
T value S [2] is set as knock value KNK. Next, step S
Proceeding to 310, the knock value KNK is changed to the DFT value S [1].
It is determined whether the value obtained by subtracting the predetermined value exceeds a predetermined value K1. The determination condition of step S310 is satisfied, that is, the value obtained by subtracting the DFT value S [1] from the knock value KNK is equal to the predetermined value K1.
If the value exceeds the predetermined value K, the process proceeds to step S311, and the value obtained by subtracting the DFT value S [1] from the knock value KNK is equal to the predetermined value K.
It is determined whether the value exceeds a predetermined value K2 larger than 1.
The determination condition of step S311 is satisfied, that is, the knock value K
When the value obtained by subtracting the DFT value S [1] from NK is larger than the predetermined value K2, the process proceeds to step S312, where it is determined that the knock is large, and this routine ends.

On the other hand, if the determination condition of step S311 is not satisfied, that is, if the value obtained by subtracting DFT value S [1] from knock value KNK is smaller than predetermined value K2, step S3 is executed.
Then, the routine proceeds to step 13, where it is determined that the knock is small, and the routine ends. On the other hand, when the determination condition of step S305 is not satisfied, that is, when the DFT value S [4] is greater than or equal to the predetermined value K4, or when the determination condition of step S306 is not satisfied, that is, D
When the FT value S [3] is larger than the predetermined value K3 or when the determination condition of step S310 is not satisfied, that is, when the value obtained by subtracting the DFT value S [1] from the knock value KNK is smaller than the predetermined value K1. It is determined as noise and step S314
Then, it is determined that there is no knock, and this routine ends.

As described above, the control signal processing system for an internal combustion engine according to the present embodiment detects the ion current IION flowing between the ignition plug 12 disposed in the combustion chamber and the ground for each cylinder of the internal combustion engine. Spark plug 12, ignition coil 1
0, an ion current detecting means including a capacitor 15, an ion current detecting resistor 16 and the like, and an LPF 27, an HPF 28 and the like in the ECU 20 for extracting a predetermined frequency component included in the ion current IION detected by the ion current detecting means. This is achieved by the frequency component extracting means and the ECU 20 which performs analog-to-digital conversion of the predetermined frequency component extracted by the frequency component extracting means by the A / D converter 42 and performs frequency analysis using the A / D converted value. Calculating means for determining the operating state of the internal combustion engine based on the frequency analysis result of the A / D converted value by the calculating means
Operating state determination means achieved by the CU 20.

That is, a predetermined frequency component included in the ion current IION flowing between the spark plug 12 and the ground is extracted by the LPF 27, the HPF 28, and the like, and A / D converted by the A / D converter 42. ECU using / D conversion value
At 20, frequency analysis is performed, and the operation state of the internal combustion engine is determined based on the result. That is, in the frequency analysis after the predetermined frequency component included in the ion current IION is A / D converted and digitized, for example, the characteristic of occurrence of knock or superposition of noise is remarkably shown in the frequency analysis result. As a result, the operating state of the internal combustion engine can be accurately determined.

In the control signal processing system for an internal combustion engine according to the present embodiment, the arithmetic processing means achieved by the ECU 20 uses the arithmetic processing unit 44 by the DSP 40.
That is, in the frequency analysis using the A / D conversion value, the calculation processing using the acquisition interval of the A / D conversion value is necessary. Therefore, the calculation processing unit 44 by the DSP 40 as the CPU capable of the high-speed multiplication / addition processing is required. It is used.

In the control signal processing system for an internal combustion engine according to the present embodiment, the arithmetic processing means achieved by the ECU 20 performs frequency analysis of the A / D converted value by Fourier transform to obtain the spectrum intensity at a predetermined frequency component. Things. That is, the ECU 20 calculates the spectrum intensity at a predetermined frequency component by Fourier transform of the A / D converted value. For this reason, for example, in the knock detection processing, the spectrum intensity at the knock center frequency and the spectrum intensity at frequencies near the knock center frequency are obtained, and the transition state of the spectrum intensity corresponding to the frequency is known.

Further, in the control signal processing system for an internal combustion engine according to the present embodiment, the arithmetic processing means achieved by the ECU 20 uses the DFT algorithm as the Fourier transform of the A / D converted value. That is, according to the DFT algorithm, Fourier transform is performed every time the A / D conversion value is fetched, that is, the fetching interval of the A / D conversion value, in the gate section for fetching the A / D conversion value that is set in advance. , A DFT operation can be executed as a Fourier transform, and immediately after the end of the gate section, for example, a knock determination process can be performed using the result of the DFT operation. For this reason, it is possible to greatly reduce the processing time in the knock determination processing and the like.

In the present embodiment, the knock determination is executed by the arithmetic processing unit 44 in the DSP 40.
The DFT frequency analysis result calculated in step 40 is used by the host CPU.
50 may be communicated via the DMA 45 and the host CPU 50 may execute the knock determination.

<Embodiment 2> FIG. 12 is a block diagram showing the configuration of an ECU 20 in a control signal processing system for an internal combustion engine according to a second embodiment of the present invention. In the drawings, the same reference numerals and symbols are given to components having the same configuration or corresponding portions as those in the above-described embodiment, and detailed description thereof will be omitted. The electrical configuration for detecting the ion current is the same as that of FIG. 1 showing the circuit diagram of the above-described embodiment, and the description thereof will be omitted. Then, as described above, the ignition order in the four-cylinder internal combustion engine is # 1 cylinder → # 3 cylinder → # 4 cylinder → # 2 cylinder. In the following, disconnection detection, knock detection, misfire using ion current Of the detection and the plague detection processing, mainly the knock detection processing will be described.

In FIG. 12, the difference from the above-described embodiment is that in the knock detection processing by the arithmetic processing unit 44 of the DSP 40 in the ECU 20, F
Only the knock determination is made after the FT frequency analysis. Therefore, the control signal processing system for an internal combustion engine according to the present embodiment is applied to extract a knock detection signal, and the DSP 40
12 and 1 show a knock detection process for performing a knock determination based on the FFT frequency analysis by the arithmetic processing unit 44 in FIG.
3 will be described.

First, as shown in FIG. 12, the MPX 25 in the ECU 20 switches the # 1 ion current to the # 4 ion current to extract a knock detection signal necessary for the knock detection process (FIG. 13 (a)). reference). This signal is LPF2
7 removes unnecessary high-frequency noise components at the time of knock detection, and also removes low-frequency noise components via the HPF 28, and then amplifies via the AMP 29 (see FIG. 13B). . The knock detection signal amplified by the AMP 29 is input to the A / D converter 42 via the MPX 41 in the DSP 40. The knock detection signal preprocessed in this manner is supplied to the A / D converter 4 in the DSP 40.
A / D conversion is performed in step 2 and the A / D conversion value is stored in the corresponding storage area of the RAM 43 as an A / D conversion value for knock detection. Then, in the knock detection process of the arithmetic processing unit 44 in the DSP 40, according to the FFT frequency analysis on the A / D conversion value for knock detection, a large spectrum intensity near the knock center frequency appears (see FIG. 13C). ). Knock determination is performed based on the spectrum intensity thus obtained.

Next, a case where the control signal processing system for an internal combustion engine according to the present embodiment is applied to extract a knock detection signal and determine a knock will be described with reference to FIG. FIG. 14 is a time chart showing transition states of various signals and the like.

In FIG. 14, an ignition command signal # 1IGT output from the ECU 20 is used as the # 1 ion current.
After the pulse waveform is output at the ignition timing when the ignition goes from High to Low, if the ignition is normal after # 1 TDC, the flame spreads into the combustion chamber, and the desired waveform appears. A gate section signal as an A / D conversion value acquisition section for knock detection is sent from the host CPU 50 to the DSP 4.
0 is output in response to the FFT frequency analysis in the knock detection processing of the arithmetic processing unit 44 of 0. The gate section by this gate section signal is ATDC15 ° CA from Low to Hi.
gh and rise, ATDC60 ° CA ~ ATDC90 °
Fall from High to Low at CA. The MPX 25 for disconnection / knock / misfire detection is switched so that this gate section includes a High section and # 1 is selected. Then, a knock detection signal is obtained by switching the MPX 25 for the # 1 ion current. In the section where this gate section is High, for example, the knock detection signal
The A / D converted values for every 50 μs are sequentially stored in the RAM 43. Then, immediately after the gate section changes from High to Low, the FFT calculation processing is performed, and the knock determination processing is performed based on the calculation result.

That is, the difference from the first embodiment described above is that after the A / D converted values in the gate section are sequentially stored in the RAM 43, the FFT operation processing is performed immediately after the end of the gate section, and the knock determination processing is performed. It is only that. This F
In the FT frequency analysis, arithmetic processing cannot be performed unless all A / D conversion values in the gate section are captured.

Next, the A / D conversion value storage and the FFT frequency of the knock detection signal in the DSP 40 in the ECU 20 used in the control signal processing system for the internal combustion engine according to the second embodiment of the present invention. A description will be given based on the flowchart of FIG. 15 showing the processing procedure of the analysis. The A / D conversion value storage and the FFT frequency analysis routine are repeatedly executed by the DSP 40 at interruptions of 50 μs.

In FIG. 15, it is determined in step S401 whether or not the gate is ON based on the gate section signal from the host CPU 50. When the determination condition of step S401 is satisfied, that is, during the gate section in which the gate is ON, the process proceeds to step S402, and the A / D converted value is captured. Next, the process proceeds to step S403, where writing to the storage area in the RAM 43 is performed. Next, the routine proceeds to step S404, where the frequency analysis start flag is turned ON, and this routine ends. In this way, the A / D converted values are sequentially stored in the RAM 43 during the gate section in which the gate is ON.

On the other hand, if the judgment condition of step S401 is not satisfied, that is, if the gate is OFF, step S4
05, it is determined whether the flag is ON. When the determination condition of step S405 is satisfied, that is, when the frequency analysis flag is ON, the process proceeds to step S406, and RA
Well-known FFT using A / D conversion values stored in M43
A frequency analysis process is performed. Next, the process proceeds to step S407, in which a knock determination process described later based on the result of the FFT frequency analysis in step S406 is performed. Next, the routine proceeds to step S408, where the frequency analysis start flag is turned off, and this routine ends. On the other hand, step S4
When the determination condition of 05 is not satisfied, that is, when the frequency analysis start flag is OFF, this routine ends without performing anything.

Next, a description will be given, with reference to FIG. 17, based on a flowchart of FIG. 16 showing a processing procedure for knock determination in step S407 of FIG. Here, FIG. 17 is an explanatory diagram showing an example of the distribution of the spectrum intensity in the handling frequency range of 1 kHz to 10 kHz. Note that this knock determination routine is performed by an interrupt every 50 μs.
It is repeatedly executed at P40.

In FIG. 16, in step S501, the FFT calculation value of the knock center frequency f0 is R0, and the frequency (f0
+ Α) is R1 and the largest FFT calculation value in the handling frequency range is R2. Here, α is about 1 kHz
Is set to Next, the process proceeds to step S502, where the determination values K2, KN0, KN1,
KL1, KL2, KS0, and KS1 are determined. Next, the processing shifts to step S503, where the largest F
It is determined whether the FT operation value R2 is less than the determination value K2. When the determination condition of step S503 is satisfied, that is, when the maximum FFT calculation value R2 in the handling frequency range is smaller than the determination value K2 and has the relationship shown in FIG. 17A, the process proceeds to step S504, and there is no knock. Is determined, and this routine ends.

On the other hand, the determination condition of step S503 is not satisfied, that is, the maximum FFT calculation value R2 in the handling frequency range.
Is larger than the determination value K2, the process proceeds to step S505, where the FFT calculation value R0 of the knock center frequency f0 is equal to the largest FFT calculation value R2 in the handling frequency range, and the FFT calculation value R0 of the knock center frequency f0 is determined. Value KN
FFT operation value R1 exceeding 0 and having a frequency (f0 + α)
Is smaller than the determination value KN1. Step S
When the determination condition of 505 is satisfied, that is, when the relationship is as shown in FIG. 17B, the process proceeds to step S506, and the frequency (f) is calculated from the FFT calculation value R0 of the knock center frequency f0.
0 + α) is the determination value KL obtained by subtracting the FFT calculation value R1.
It is determined whether the number exceeds one. If the determination condition of step S506 is satisfied, that is, if the FFT calculation value R0 of the knock center frequency f0 is larger than the value obtained by adding the determination value KL1 to the FFT calculation value R1 of the frequency (f0 + α), step S
The flow shifts to 507, where it is determined that knock is large, and this routine ends.

On the other hand, the determination condition of step S506 is not satisfied, that is, the FFT calculation value R0 of the knock center frequency f0.
If the value obtained by subtracting the FFT calculation value R1 of the frequency (f0 + α) from the value is equal to or smaller than the determination value KL1, the process proceeds to step S508.
And the same value is smaller than the determination value KL1.
It is determined whether the number exceeds two. The determination condition of step S508 is satisfied, that is, as shown in FIG. 17C, the frequency (f0) is calculated from the FFT calculation value R0 of the knock center frequency f0.
+ Α) is the determination value KL2
If it is larger than the threshold value, the process proceeds to step S509, where it is determined that the knock is small, and the routine ends. Here, when the determination condition of step S508 is not satisfied, that is, when the value obtained by subtracting the FFT calculation value R1 of the frequency (f0 + α) from the FFT calculation value R0 of the knock center frequency f0 is equal to or smaller than the determination value KL2, the process proceeds to step S510. Then, it is determined that there is no knock, and this routine ends.

On the other hand, if at least one of the judgment conditions in step S505 is not satisfied, the flow shifts to step S511, where the FFT calculation value R0 of the knock center frequency f0 is larger than the judgment value KS0 and is larger than the FFT of the frequency (f0 + α).
It is determined whether the calculated value R1 is larger than the determination value KS1. The determination condition of step S511 is satisfied, that is, FIG.
If the relationship is as shown in (d), step S51
Then, the routine goes to 2 and is determined to be noise A, and this routine ends. The noise A is generated when a large current flows due to passing or a horn. On the other hand, step S511
If at least one of the determination conditions is not satisfied, the flow shifts to step S513, and as shown in FIG. 17 (e), it is determined to be noise B, and this routine ends. The noise B is generated by various disturbance noises.

In this embodiment, the arithmetic processing unit 44 in the DSP 40 analyzes the FFT frequency and makes a knock determination. However, as shown in FIG.
Knock determination may be performed by host CPU 50 based on the frequency analysis result.

As described above, the control signal processing system for an internal combustion engine according to the present embodiment detects the ion current IION flowing between the ignition plug 12 provided in the combustion chamber and the ground for each cylinder of the internal combustion engine. Spark plug 12, ignition coil 1
0, an ion current detecting means including a capacitor 15, an ion current detecting resistor 16 and the like, and an LPF 27, an HPF 28 and the like in the ECU 20 for extracting a predetermined frequency component included in the ion current IION detected by the ion current detecting means. This is achieved by the frequency component extracting means and the ECU 20 which performs analog-to-digital conversion of the predetermined frequency component extracted by the frequency component extracting means by the A / D converter 42 and performs frequency analysis using the A / D converted value. Calculating means for determining the operating state of the internal combustion engine based on the frequency analysis result of the A / D converted value by the calculating means
Operating state determination means achieved by the CU 20.

That is, a predetermined frequency component contained in the ion current IION flowing between the spark plug 12 and the ground is extracted by the LPF 27, the HPF 28, and the like, and A / D converted by the A / D converter 42. ECU using / D conversion value
At 20, frequency analysis is performed, and the operation state of the internal combustion engine is determined based on the result. That is, in the frequency analysis after the predetermined frequency component included in the ion current IION is A / D converted and digitized, for example, the characteristic of occurrence of knock or superposition of noise is remarkably shown in the frequency analysis result. As a result, the operating state of the internal combustion engine can be accurately determined.

In the control signal processing system for an internal combustion engine according to the present embodiment, the arithmetic processing means achieved by the ECU 20 uses the arithmetic processing unit 44 by the DSP 40.
That is, in the frequency analysis using the A / D conversion value, all A
The arithmetic processing unit 44 by the DSP 40 as a CPU capable of high-speed multiplication / addition processing is used because the arithmetic processing immediately after fetching the / D conversion value is required.

In the control signal processing system for an internal combustion engine according to the present embodiment, the arithmetic processing means achieved by the ECU 20 performs frequency analysis of the A / D conversion value by Fourier transform to obtain the spectrum intensity at a predetermined frequency component. Things. That is, the ECU 20 calculates the spectrum intensity at a predetermined frequency component by Fourier transform of the A / D converted value. For this reason, for example, in the knock detection processing, the spectrum intensity at the knock center frequency and the spectrum intensity at frequencies near the knock center frequency are obtained, and the transition state of the spectrum intensity corresponding to the frequency is known.

Further, in the control signal processing system for an internal combustion engine according to the present embodiment, the arithmetic processing means achieved by the ECU 20 uses the FFT algorithm as the Fourier transform of the A / D converted value. In other words, according to the FFT algorithm, all A / D conversion values are captured in a gate section that is set in advance for A / D conversion value capture,
Immediately after the end of the gate section, an FFT operation is performed as a Fourier transform, and for example, a knock determination process can be performed using the result of the FFT operation. Therefore, the reliability in knock determination processing and the like is improved.

In the above embodiment, the DFT frequency analysis and the FFT frequency analysis are performed by the knock detection processing in the arithmetic processing unit 44 of the DSP 40. However, the present invention is not limited to this. No, FIR
The frequency analysis may be performed using a (Finite Impulse Response) filter, an IIR (Infinite Impulse Response) filter, or the like.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an electrical configuration for detecting an ion current in a control signal processing system for an internal combustion engine according to a first example and a second example of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an ECU in a control signal processing system for an internal combustion engine according to a first example of an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between a frequency of a knock detection signal extracted by applying the control signal processing system for an internal combustion engine according to the first embodiment of the present invention and a spectrum intensity; is there.

FIG. 4 is a time chart showing transition states of various signals and the like in the control signal processing system for an internal combustion engine according to the first example of the embodiment of the present invention.

FIG. 5 is an enlarged view showing a relationship between a gate section and a knock detection signal in FIG. 4;

FIG. 6 is an explanatory diagram showing the knock detection signal of FIG. 5 in a further enlarged manner.

FIG. 7 is a DF used in a control signal processing system for an internal combustion engine according to a first example of an embodiment of the present invention;
This is the determinant of the T operation.

FIG. 8 is a table of a sine function stored in a ROM in the control signal processing system for an internal combustion engine according to the first example of the embodiment of the present invention.

FIG. 9 is a flowchart showing a procedure of a base control of knock detection in a DSP in an ECU used in a control signal processing system for an internal combustion engine according to a first example of an embodiment of the present invention. .

FIG. 10 is a flowchart illustrating a processing procedure of the DFT operation in FIG. 9;

FIG. 11 is a flowchart illustrating a processing procedure of knock determination in FIG. 9;

FIG. 12 is an EC in a control signal processing system for an internal combustion engine according to a second example of the embodiment of the present invention;
FIG. 3 is a block diagram showing a configuration of U.

FIG. 13 shows an ion current waveform in a control signal processing system for an internal combustion engine according to a second example of the embodiment of the present invention, an extracted waveform thereof, and a relationship between a frequency and a spectrum intensity in the waveform. FIG.

FIG. 14 is a time chart showing transition states of various signals and the like in the control signal processing system for an internal combustion engine according to the second example of the embodiment of the present invention.

FIG. 15 is a diagram showing a knock detection signal A / A of a DSP in an ECU used in a control signal processing system for an internal combustion engine according to a second example of the embodiment of the present invention.
It is a flowchart which shows the processing procedure of D conversion value storage and FFT frequency analysis.

FIG. 16 is a flowchart illustrating a processing procedure of knock determination based on the frequency analysis result of FIG.

FIG. 17 is an explanatory diagram showing an example of the distribution of the spectrum intensity in the frequency range handled by the control signal processing system for an internal combustion engine according to the second example of the embodiment of the present invention.

FIG. 18 is an EC in the control signal processing system for an internal combustion engine according to the second example of the embodiment of the present invention.
It is a block diagram which shows the modification of the structure of U.

[Explanation of symbols]

 12 spark plug 20 ECU (electronic control unit) 40 DSP (digital signal processor) 42 A / D converter 43 RAM 45 DMA

Claims (9)

[Claims] 1. An ion current detecting means for detecting an ion current flowing between a spark plug disposed in a combustion chamber and a ground for each cylinder of an internal combustion engine, and the ions detected by the ion current detecting means. Frequency component extraction means for extracting a predetermined frequency component contained in the current; analog-digital conversion of the predetermined frequency component extracted by the frequency component extraction means; and frequency analysis using the A / D converted value. Control signal processing for an internal combustion engine, comprising: an arithmetic processing means; and an operating state determining means for determining an operating state of the internal combustion engine based on a frequency analysis result of the A / D converted value by the arithmetic processing means. system. 2. The arithmetic processing means includes a digital signal processor (DSP).
The control signal processing system for an internal combustion engine according to claim 1, wherein a signal processor (digital signal processor) is used. 3. The arithmetic processing unit according to claim 1, wherein the arithmetic processing unit obtains a spectrum intensity in the predetermined frequency component by performing a frequency analysis of the A / D converted value by Fourier transform. Control signal processing system for internal combustion engines. 4. The arithmetic processing means performs a Fourier transform of the A / D converted value as a DFT (Discrete Fourier Transform).
The control signal processing system for an internal combustion engine according to claim 3, wherein an algorithm is used. 5. The arithmetic processing means as a Fourier transform of the A / D conversion value.
The control signal processing system for an internal combustion engine according to claim 3, wherein an m: fast Fourier transform) algorithm is used. 6. The control signal processing system for an internal combustion engine according to claim 3, wherein said arithmetic processing means makes a knock determination based on a spectrum intensity of said predetermined frequency component. 7. The control signal processing system for an internal combustion engine according to claim 6, wherein a plurality of the frequency components are provided. 8. The control signal processing system for an internal combustion engine according to claim 6, wherein the frequency component is transmitted from outside. 9. An ion current detecting means for detecting an ion current flowing between a spark plug disposed in a combustion chamber and a ground for each cylinder of the internal combustion engine, and an analog-digital conversion of the ion current. A
A control signal for an internal combustion engine, comprising: an arithmetic processing means for performing an arithmetic operation in a DSP using a / D conversion value; Processing system.