JPH06207876A - Method and apparatus for knocking control - Google Patents

Abstract

PURPOSE:To enhance the stability of criteria for knocking and the response of judgement to knocking. CONSTITUTION:The output from a knock sensor undergoes frequency analysis during a period W1 corresponding a given crank angle between the instant the piston of a firing cylinder reaches the top dead center in response to a crank pulse and the instant the piston of the next cylinder reaches the top dead center. On the basis of the analysis result, the knocking criterion V is obtained from an index value S to be set to the maximum value of the spectrum power by the following equation. V={V(i-1)X(m-1)+Si}/mo where, Si: Index of this time, V(i-1): Preceding criteria, m: Filter constant to show the degree of annealing. The filter constant (m) can vary according to at least one of the cylinders, frequency zones, or rotation speed zones of an internal combustion engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knocking control method and device suitably implemented in an ignition timing control device for an internal combustion engine.

[0002]

2. Description of the Related Art In the conventional knocking control method for controlling the ignition timing of an internal combustion engine,
Of the output from the knock sensor that detects vibrations due to knocking of the internal combustion engine, only the frequency component due to knocking is filtered by a bandpass filter, and the filtered output is subjected to analog / digital conversion, and then level discrimination is performed according to a predetermined knocking determination standard. Thus, the presence or absence of knocking is determined, and the ignition advance amount is controlled according to the determination result. The knocking determination criterion is, for example, data that predetermines the maximum value of the conversion result in a predetermined observation period from when the piston of a certain cylinder reaches top dead center to when the piston of the next cylinder reaches top dead center. It is set to the average value of the numbers.

[0003]

In the above-mentioned prior art,
The number of data is a predetermined constant number. On the other hand, if the number of data is increased, for example, the stability is improved, but the responsiveness to load fluctuation is poor. Therefore, if the number of data is fixed as described above, it becomes impossible to achieve both stability and responsiveness.

An object of the present invention is to provide a knocking control method and device capable of achieving both stability and responsiveness.

[0005]

According to the present invention, a knocking observation period is set at a predetermined timing between the top dead centers of pistons in response to the output of a crank angle sensor, and the frequency of the output of the knock sensor during the observation period is set. Analysis is performed, a value calculated based on the spectrum power over the observation period is set as an index value S from the spectrum distribution of the analysis result, and knocking is performed based on the index value S and a predetermined knocking determination standard V. A knocking control method for performing a determination and controlling an ignition advance according to the determination result, wherein the knocking determination standard V is a previous knocking determination standard V (i-1), and a filter constant m is a natural number. Then, the index value Si at this time is obtained by performing a filter process by V = {V (i−1) × (m−1) + Si} / m to obtain the filter constant It is a knocking control method characterized in that several m can be changed in accordance with the condition of the internal combustion engine.

Further, according to the present invention, in response to the output of the crank angle sensor, a knocking observation period is set at a predetermined timing between the top dead centers of the pistons, and the frequency of the output of the knock sensor is analyzed during the observation period. From the spectrum distribution of the analysis result, a value calculated based on the spectrum power over the observation period is set as the index value S, and knocking determination is performed based on the index value S and a predetermined knocking determination standard V, and A knocking control method for controlling an ignition advance angle according to a determination result, wherein the knocking determination criterion V is such that an index value of this time is Si, an index value of a previous time is S (i-1), and an index value of the last two times. S (i-2), ...
And when the filter constant m is a natural number, V = {Si + S (i-1) + S (i-2) + ... S (i-
m + 1)} / m, and the filter constant m is made variable according to the condition of the internal combustion engine.

Furthermore, in the present invention, in the spectrum distribution of the analysis result, a plurality of frequency bands that may include a signal component indicating the occurrence of knocking are preset, and an index value is set for each frequency band. When S is obtained and the corresponding knocking determination standard V is obtained from the index value S, the filter constant m is set for each of the frequency bands.

Further, according to the present invention, the cylinder corresponding to the index value S is discriminated in response to the output of the crank angle sensor, and the index constant S is calculated from the index value S by using the filter constant m preset for each cylinder. It is characterized in that the knocking determination standard V is obtained.

Furthermore, the present invention detects the rotational speed of the internal combustion engine in response to the output of the crank angle sensor, determines which of a plurality of predetermined rotational speed bands the detection result belongs to, and The knocking criterion V is obtained from the index value S using the filter constant m preset for each rotational speed band.

Further, according to the present invention, in the spectrum distribution of the analysis result, a plurality of frequency bands that may include a signal component indicating occurrence of knocking are preset, and the index value S is set for each frequency band. In determining the corresponding knocking determination reference V from the index value S, the cylinder corresponding to each index value S is determined in response to the output of the crank angle sensor, and the rotation speed of the internal combustion engine is detected. Then, it is determined which of a plurality of predetermined rotational speed bands the detection result belongs to, and the filter constant m is set for each frequency band, each cylinder, and each rotational speed band. And

Further, according to the present invention, the filter constant m for each frequency band, each cylinder, and each rotational speed band is set.
Is stored as a map.

Further, the knocking determination criterion V of the present invention is
Is determined based on up to the previous index value S (i-1), determines that knocking is present when the knocking criterion V exceeds the knocking determination reference V, and knocks with the current index value Si. It is characterized in that the update of the criterion V is suspended.

Still further, according to the present invention, a knock sensor for detecting knocking of the internal combustion engine, a crank angle sensor for detecting a rotational angle position of the internal combustion engine, and a piston of the internal combustion engine in response to an output of the crank angle sensor. Analyzing means for performing frequency analysis of the output from the knock sensor in a knocking observation period set during a predetermined timing between top dead centers, and an index value for obtaining an index value over the observation period from the analysis result of the analyzing means. Setting means, judgment reference creating means for filtering the index value to create a knocking judgment reference, knocking judgment based on the index value and knocking judgment reference, and ignition advance angle corresponding to the judgment result. And a control means for controlling the.

[0014]

According to the present invention, in response to the output of the crank angle sensor, when the internal combustion engine is, for example, a four-cylinder, four-cycle internal combustion engine, every 180 ° crank angle (hereinafter referred to as ° CA), or 6 In the case of a cylinder, in every 120 ° CA, in the period from when the piston of a certain cylinder reaches the top dead center to when the piston of the next cylinder reaches the top dead center,
For example, the knocking observation period is set between 10 ° and 110 ° CA from the top dead center. In the observation period, the frequency analysis of the output of the knock sensor realized by the piezoelectric element or the like is performed, that is, the spectrum power at each frequency is analyzed.

From the spectrum distribution of the analysis result, for example, the maximum value of all spectrum power over the observation period is set as the index value S. This index value S is used as a knocking determination reference V, the previous value of the knocking determination reference V is V (i-1), and the current value of the index value S is S
When i and m are natural number filter constants, V = {V (i−1) × (m−1) + Si} / m is used for filtering. That is, the knocking determination standard V is obtained by so-called 1 / m annealing. When the current index value Si exceeds the knocking determination reference V, it is determined that knocking has occurred, and the ignition advance amount is controlled to be small.

According to the present invention, the knocking determination standard V is set such that the current index value is Si and the previous index value is S (i
−1), when the index value of the previous two times is S (i-2), ..., V = {Si + S (i-1) + S (i-2) + ... S (i-
m + 1)} / m. That is, it may be obtained by a simple average of previous values up to the m-1 calculation cycle.

Furthermore, the filter constant m can be changed according to the conditions of the internal combustion engine. Ie, for example,
Preferably, in the spectrum distribution of the frequency analysis result, there is a possibility that a signal component indicating occurrence of knocking is included, for example, 7 kHz, 11 kHz, 13 kHz.
A plurality of frequency bands are set in advance with frequencies such as z, 15 kHz and 19 kHz as the center frequencies, and the maximum value is calculated for each set frequency band to set the index value S. To do. When obtaining the knocking determination reference V corresponding to the index value S for each frequency band, the filter constant m may be changed for each frequency band.

Therefore, for example, in each of the frequency bands, the filter constant m is set large in a frequency band susceptible to noise such as valve opening / closing noise and ignition noise, and the filter constant m in the remaining frequency band is set small. By setting it, it is possible to prevent erroneous determination of knocking due to noise and improve stability, and it is possible to adjust the ignition advance amount with good responsiveness when knocking occurs.

Further preferably, the cylinder to which the index value S corresponds is discriminated in response to the output of the crank angle sensor,
The knocking determination standard V may be obtained using a filter constant m preset for each cylinder.

Therefore, for example, the more the cylinder is located farther from the knock sensor where the detection sensitivity becomes lower, the larger the filter constant m can be to prevent erroneous determination due to noise or the like.

Still more preferably, the rotational speed band of the internal combustion engine is, for example, 1000 rpm, 1000 to 200.
The filter constant m is set in advance for each 0 rpm, ... To determine which of the plurality of rotational speed bands the rotational speed of the internal combustion engine detected in response to the output of the crank angle sensor belongs to, The knocking determination standard V may be obtained from the index value S using the filter constant m of the determined band.

Therefore, by changing the filter constant m in accordance with the load state of the internal combustion engine, it is possible to improve the responsiveness when knocking occurs while maintaining the stability in the steady state.

Furthermore, the filter constant m may be set for each rotational speed band of each cylinder for each frequency band, and in this case, the filter constant m is preferably stored as a map. It

Further, the knocking determination standard V may be obtained based on the previous index value S (i-1),
Further, in this case, it is determined that knocking has occurred when the index value Si of this time exceeds the obtained knocking determination standard V, and the next update of the knocking determination standard V by the index value Si is stopped. You may As a result, it is possible to suppress large fluctuations in the knocking determination reference V and improve stability accuracy.

Further, according to the present invention, in performing the knocking determination as described above, it is realized by a piezoelectric element or the like,
With a knock sensor that can be attached to a cylinder block,
A crank angle sensor for detecting the rotational angle position of the crankshaft, an analyzing means for performing the frequency analysis, an index value setting means for obtaining the index value from the analysis result, and a filter processing of the obtained index value as described above. Then, the control means makes knocking determination as described above based on the obtained index value and the knocking determination reference, and the ignition progress is made corresponding to the determination result. Control the corners.

[0026]

1 is a block diagram showing an electrical configuration of an ignition timing control system 1 for an internal combustion engine in which a knocking control method according to an embodiment of the present invention is used. The knock sensor 2, which is realized by a piezoelectric element such as a so-called piezo-type acceleration sensor, is fixed to a cylinder block of an internal combustion engine. The output from the knock sensor 2 is input to the analog / digital converter 4 via a low-pass filter (abbreviated as LPF) 3 having a cutoff frequency of 20 kHz, for example, in order to prevent aliasing noise.

On the other hand, from the crank angle sensor 5 provided for detecting the rotational angle position of the internal combustion engine, every time the piston of the cylinder about to enter the ignition stroke reaches the top dead center, that is, for example, the internal combustion engine. Is a 4-cylinder 4-cycle internal combustion engine, a crank pulse is derived every 180 ° CA, and when it is 6-cylinder, 120 ° CA
A crank pulse is derived every time. The crank pulse is input to the sampling signal generating circuit 7 via the input interface circuit 6. A sampling signal is derived from the sampling signal generation circuit 7 in response to the crank pulse, and the analog / digital converter 4 outputs the sampling signal.
Converts the output from the knock sensor 2 into a digital value at a sampling frequency of, for example, 40 kHz in synchronization with the sampling signal, and then outputs the digital value to the frequency analyzer 8.

The frequency analyzer 8 is realized by a so-called digital signal processor or the like, and performs frequency analysis on the knock sensor output converted into a digital value by a fast Fourier transform method in synchronization with the sampling signal. , And outputs the analysis result to the knocking determination circuit 9. The knocking determination circuit 9 determines a knocking signal from the knocking frequency created based on the output of the frequency analyzer 8 and the knocking frequency band width and signal level to be filtered in order to pass only the knocking signal, as described later. Based on the knocking determination standard V, it is determined whether or not knocking has occurred, and the determination result is derived to the control circuit 11 realized by a microcomputer or the like.

In connection with the control circuit 11, there are provided an intake pressure sensor 12, a cooling water temperature sensor 13, and other sensors 14 such as an intake temperature sensor and a throttle valve opening sensor. The detection result of 14 is input to the analog / digital converter 16 via the input interface circuit 15, converted into a digital value, and then input to the control circuit 11. The crank pulse from the crank angle sensor 5 is also input to the control circuit 11, and the control circuit 11 responds to the crank pulse by the determination result of the knocking determination circuit 9 and the sensor 1.
The ignition advance amount is calculated based on the detection results of 2 to 14.
The control circuit 11 outputs an ignition signal to the igniter 18 via the output interface circuit 17 so that the ignition advance amount thus calculated is obtained, and the ignition timing of the ignition plug 19 is drive-controlled. In this way, it is possible to suppress the occurrence of knocking and perform ignition timing control with a large ignition advance amount.

FIG. 2 is a diagram for explaining the concept of the knocking determination method of the present invention. For the output shown in FIG. 2A from the knock sensor 2, the observation period W1 is
Between the top dead center (TDC) of the piston, it is set to a period from when the period W2, for example, 10 ° CA, elapses from the top dead center to when 110 ° CA is reached.

Now, when the internal combustion engine has four cylinders and four cycles, and the rotation speed of the internal combustion engine detected by the crank angle sensor 5 is 3000 rpm, the interval between the top dead centers is 180.
It becomes CA, and the time becomes 10 msec. Also,
The start time of the observation period W1 after the period W2 has elapsed is a time point after 0.56 msec from the top dead center,
The end of the observation period W1 is 6.11 m from the top dead center.
This is the time when sec has elapsed.

The frequency analyzer 8 is shown in FIG. 3 and FIG. 2 based on all the sampling data in the observation period W1.
As shown in (2), the spectrum power at each of the plurality of frequencies is analyzed in the frequency band of 0 to 20 kHz. The knocking determination circuit 9 compares the analysis result with, for example, 7 kHz, 11 kHz, 13 kHz,
Indicated by reference numerals F1, F2, F3, F4, F5 (indicated by reference numeral F when collectively referred to), centering on frequencies that may include signal components representing the occurrence of knocking, such as 15 kHz and 19 kHz. Thus, a plurality of frequency bands F are set in advance.

The knocking determination circuit 9 first determines the maximum value Pf1 of the spectrum power in each frequency band F.
Pf2, Pf3, Pf4 and Pf5 are determined, and FIG.
As shown by, the index value S for each frequency band F
It is set to f1, Sf2, Sf3, Sf4 and Sf5 (denoted by reference numeral S when collectively referred to). From each index value S thus obtained, the knocking determination standard V for each frequency band F
Is calculated from the following formula.

V = {V (i−1) × (m−1) + Si} / m (1) However, V (i−1) is the previous knocking determination standard, and Si is in each frequency band F. It is the index value at this time,
The filter constant m is a natural number. The filter constant m
Is likely to include valve opening / closing noise, ignition noise, etc. in the knocking signal component, for example, in the frequency band F.
A relatively large value for the constant mf3 of 3, for example, 1
2 and the remaining frequency bands F1, F2, F4, F
8 for the constants mf1, mf2, mf4, mf5 of 5
Is set to. That is, in the frequency band F3, the so-called smoothing time constant or the smoothing degree is increased. As a result, in the frequency band F3, erroneous determination due to the noise can be prevented and stability can be improved.
In the remaining frequency bands F1, F2, F4, F5, knocking determination can be quickly performed in response to the knocking signal component. When it is determined that knocking is present in three frequency bands from the determination results in each frequency band F, knocking determination circuit 9 controls ignition advance amount to be small via control circuit 11.

The knocking criterion V is an index value S (i−m +) up to m−1 calculation cycle, as shown in the following equation.
It may be the average value of 1).

V = {Si + S (i-1) + S (i-2) + ... S (i-m + 1)} / m (2) where S (i-1) is the previous index value and S (I-
2) is the index value two times before, and S (i-m + 1) is m-
The index value is one calculation cycle before. Further, instead of simple addition as described above, each index value Si, S
The weighting may be performed by multiplying (i-1), ... By the coefficients α1, α2 ,.

V = {Si * α1 + S (i-1) * α2 + S (i-2) * α3 + ... S (i-m + 1) * αm} / m (3) FIG. 4 shows each frequency band in FIG. 7 is a flowchart for explaining an index value setting operation for each F. Step m
At 1, each index value S1 to S5 is reset to 0. In step m2, the count value i of the counter is reset to 0. The minimum value of the count value i is 0, and the maximum value is that the analysis target frequency is f0 to fnHz,
When the resolution of the frequency analyzer 8 is fdHz, (fn
It becomes an integer value of −f0) / fd.

At step m3, all frequencies f0 to f
It is determined whether or not the determination operation of the spectrum power for n has been completed, and if not, the process proceeds to step m4. In step m4, the spectrum power Pi of the i-th frequency fi is read, and in step m5, it is judged whether or not the frequency fi is within the frequency band F1, and if so, the process moves to step m6. In step m6, the maximum value Pf1 up to that point in the frequency band F1 and the spectrum power Pi of this time are compared,
When the spectrum power Pi of this time is large, the maximum value Pf1 is updated to the spectrum power Pi of this time in step m7, and then the process proceeds to step m8. If not, the process directly proceeds to step m8. In step m8, 1 is added to the count value i to update the count value i, and then the process returns to step m3, and thus the maximum value P of the frequency band F1 is obtained.
When f1 is determined, the above steps m5 to m
Go to 9.

In step m9, it is judged whether or not the frequency fi is within the frequency band F2, and if so, the maximum value Pf2 up to that point in the frequency band F2 is compared with the current spectrum power Pi in step m10. When the current spectrum power Pi is large, the maximum value Pf2 is updated to the current spectrum power Pi in step m11, and then the process returns from step m8 to step m3. Thus, the maximum value Pf of the frequency band F2
When 2 is determined, the maximum values Pf3 to Pf5 of the remaining frequency bands F3 to F5 are obtained by the same operation. In steps m12 and m13, the peak value P of the frequency band F5
After f5 is obtained, steps m8 to m3
When the determination operation of all spectrum power up to the frequency fn is completed, the operation is completed from step m3.

FIG. 5 shows an ignition timing control device 21 for an internal combustion engine in which a knocking control method according to another embodiment of the present invention is used.
FIG. 3 is a block diagram showing the electrical configuration of this embodiment, and this embodiment is similar to the above-mentioned embodiment, and the corresponding portions bear the same reference numerals. In this embodiment, the frequency analysis result of the output from the knock sensor 2 shown in FIG. 6 (1) first responds to the discrimination output from the cylinder discrimination circuit 10 corresponding to the crank pulse shown in FIG. 6 (2). In the knocking determination circuit 9, cylinder determination is performed as shown in FIG. 6 (3). Next, in the analysis result for each cylinder, the maximum values P1, P2, P3, P4 of the spectrum power of the analysis result for each cylinder are indexed as shown in FIG. Set to the values S1, S2, S3, S4.

For the set index values S1 to S4, corresponding filter constants m1 to m4 (indicated by reference numeral m when collectively referred to) are used, and the above-mentioned expressions 1 to 3 are used.
By performing any one of the above filter calculations, knocking determination standards V1 to V4 for each cylinder are obtained.

In this embodiment, the top dead center is 180 °.
Although it is a 4-cylinder internal combustion engine with CA, 12
In the case of a 6-cylinder internal combustion engine having a top dead center at every 0 ° CA, six index values S and filter constants m are also set.
Further, in the case of an 8-cylinder internal combustion engine, for example, the first cylinder and the fifth cylinder have the same ignition timing. Therefore, in such a case, a plurality of knock sensors 2 are provided and the knock assigned to each cylinder is assigned. The output of each sensor 2 may be subjected to frequency analysis.

As described above, the filter constant m is set for each cylinder.
For example, for a cylinder distant from the knock sensor 2, the S / N ratio of the vibration component of knocking decreases, so that the filter constant m is set to a relatively large value and knocking due to noise occurs. False determination can be prevented.

FIG. 7 is a block diagram showing the electrical construction of an ignition timing control device 31 of still another embodiment of the present invention, which is similar to the above-mentioned embodiment and the same reference numerals are given to corresponding parts. Attach. In this embodiment, the crank pulse from the crank angle sensor 5 is also input to the rotation speed determination circuit 20. The rotation speed determination circuit 20 detects the rotation speed of the internal combustion engine from the cycle W0 of the crank pulse shown in FIG. 8 (1), and the rotation speed is determined in advance in a plurality of rotation speed bands N1, N2 ,. Is indicated by reference sign N)
It is determined which band of the band. Corresponding to the discrimination results of the cylinder discriminating circuit 10 and the rotational speed discriminating circuit 20, as shown in FIG. 8C, filter constants m1f1 to m1.
f5 is changed.

That is, the knock sensor output shown in FIG. 8 (1) is subjected to frequency analysis within the observation period W1 as shown in FIG. 8 (2), and in the analysis result, for each frequency band F of each cylinder. Then, the index values Sf1 to Sf5 are obtained. These index values Sf1 to Sf5 are preset filter constants m1f1 to m1f as shown in Table 1 for each rotation speed band N for each frequency band F for each cylinder.
5; m2f1 to m2f5; m3f1, ... Performs a filter operation to obtain knocking determination standards Vf1 to Vf5 for each frequency band F1 to F5.

[0046]

[Table 1]

The contents of Table 1 are as follows:
It is stored as a map inside.

FIG. 9 is a diagram for explaining the concept of the knocking determination method of another embodiment of the present invention. In this embodiment, the knock sensor output shown in FIG. 9 (1) is output at the observation period W1 in the same manner as in the embodiment shown in FIG.
Frequency analysis is performed as shown in (2). In the analysis result, the maximum values Pf1 to Pf5 of the spectrum power in the frequency bands F1 to F5 are shown in FIG.
The index values Sf1 to Sf5 are set as indicated by (3).

It should be noted that in this embodiment, each index value S
Knocking determination criteria Vf1 to Vf5 based on f1 to Sf5
Of the frequency bands F1 to F1 as described above.
If it is determined that knocking is present in three or more of F5, the operation is suspended.

As a result, it is possible to prevent the determination criteria Vf1 to Vf5 from largely fluctuating due to occurrence of knocking, and to always perform stable knocking determination with the knocking determination criteria Vf1 to Vf5.

[0051]

As described above, according to the present invention, when the knocking determination reference V is obtained by filtering the index value S obtained by frequency analysis of the knock sensor output,
Since the filter constant m that determines the degree of the smoothing process is changed in accordance with the frequency band, the cylinder of the internal combustion engine, or the load state, it is possible to improve the responsiveness to knocking while maintaining stability against noise and the like. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of an ignition timing control device 1 for an internal combustion engine in which a knocking control method according to an embodiment of the present invention is used.

FIG. 2 is a diagram for explaining the concept of a knocking determination method according to an embodiment of the present invention.

FIG. 3 is a diagram showing an example of a frequency analysis result.

FIG. 4 is a flowchart for explaining an index value setting operation in FIG.

FIG. 5 is a block diagram showing an electrical configuration of an ignition timing control device 21 in which a knocking control method according to another embodiment of the present invention is used.

FIG. 6 is a diagram for explaining the concept of the knocking determination method of the embodiment shown in FIG.

FIG. 7 is a block diagram showing an electrical configuration of an ignition timing control device 31 in which a knocking control method according to still another embodiment of the present invention is used.

FIG. 8 is a diagram for explaining the concept of the knocking determination method of the embodiment shown in FIG.

FIG. 9 is a diagram for explaining the concept of a knocking determination method according to another embodiment of the present invention.

[Explanation of symbols]

 1, 21, 31 Ignition timing control device 2 Knock sensor 5 Crank angle sensor 7 Sampling signal generation circuit 8 Frequency analyzer 9 Knocking determination circuit 10 Cylinder determination circuit 11 Control circuit 12 to 14 Sensor 20 Rotation speed determination circuit S1, S2, ... Sf1, Sf2, ... Index value W1 Observation period

Claims (9)

[Claims] 1. A knocking observation period is set at a predetermined timing between the top dead center of the piston in response to the output of the crank angle sensor, and a frequency analysis of the output of the knock sensor is performed during the observation period. From the spectrum distribution, a value calculated based on the spectrum power over the observation period is set as the index value S, and knocking determination is performed based on the index value S and a predetermined knocking determination standard V, and the determination result is obtained. Correspondingly, a knocking control method for controlling an ignition advance angle, wherein the knocking determination criterion V is the previous knocking determination criterion V (i-1), and the filter constant m is a natural number, the current index value Si is obtained by filtering with V = {V (i−1) × (m−1) + Si} / m, and the filter constant m is the condition of the internal combustion engine. Knock control method characterized by enabling changes correspondingly. 2. A knocking observation period is set at a predetermined timing between the top dead center of the piston in response to the output of the crank angle sensor, and a frequency analysis of the output of the knock sensor is performed during the observation period. From the spectrum distribution, a value calculated based on the spectrum power over the observation period is set as the index value S, and knocking determination is performed based on the index value S and a predetermined knocking determination standard V, and the determination result is obtained. A knocking control method for controlling an ignition advance correspondingly, wherein the knocking determination criterion V is that the present index value is Si, the previous index value is S (i-1), and the index value of the second previous time is S (i. −
2), ... And when the filter constant m is a natural number, V = {Si + S (i-1) + S (i-2) + ... S (i-
m + 1)} / m for filtering, and the filter constant m can be changed according to the condition of the internal combustion engine. 3. In the spectrum distribution of the analysis result, a plurality of frequency bands that may include a signal component indicating the occurrence of knocking are preset, and an index value S is calculated for each frequency band, 3. The knocking control method according to claim 1, wherein the filter constant m is set for each of the frequency bands when the corresponding knocking determination reference V is obtained from the index value S. 4. A cylinder for which the index value S corresponds is discriminated in response to the output of the crank angle sensor, and a knocking judgment criterion is determined from the index value S using the filter constant m preset for each cylinder. 3. The knocking control method according to claim 1, wherein V is obtained. 5. The rotational speed of the internal combustion engine is detected in response to the output of the crank angle sensor, and it is determined which of a plurality of predetermined rotational speed bands the detection result belongs to.
3. The knocking control method according to claim 1, wherein the knocking determination reference V is obtained from the index value S using the filter constant m preset for each rotational speed band. 6. In the spectrum distribution of the analysis result, a plurality of frequency bands that may include a signal component indicating the occurrence of knocking are preset, and an index value S is calculated for each frequency band, In obtaining the corresponding knocking determination reference V from the index value S, in response to the output of the crank angle sensor, the cylinder corresponding to each index value S is determined, and the rotation speed of the internal combustion engine is detected. The filter constant m is set for each frequency band, for each cylinder, and for each rotation speed band by determining which one of a plurality of predetermined rotation speed bands the detection result belongs to. Item 3. The knocking control method according to Item 1 or 2. 7. The knocking control method according to claim 6, wherein the filter constant m for each frequency band, each cylinder, and each rotation speed band is stored as a map. 8. The knocking determination standard V is obtained based on up to a previous index value S (i-1), and when the current index value Si exceeds the knocking determination standard V, it is determined that knocking is present. The knocking control method according to any one of claims 1 to 6, wherein the updating of the knocking determination reference V by the index value Si at this time is suspended. 9. A knock sensor for detecting knocking of an internal combustion engine, a crank angle sensor for detecting a rotational angle position of the internal combustion engine, and a top dead center between pistons of the internal combustion engine in response to an output of the crank angle sensor. Of analysis means for performing a frequency analysis of the output from the knock sensor in the knocking observation period set between the predetermined timing, from the analysis result of the analyzing means, an index value setting means for obtaining an index value over the observation period, Judgment standard creating means for filtering the index value to create a knocking judgment standard; control for performing knocking judgment based on the index value and the knocking judgment standard, and controlling ignition advance corresponding to the judgment result. And a knocking control device.