JPH06200859A - Knocking control method and its device - Google Patents

Abstract

PURPOSE:To enable judgement on knocking to be made with high accuracy by collecting an index value by each cylinder of an internal combustion engine, performing filter processing of the index values, and thereby setting each knock judging reference. CONSTITUTION:An output from a knock sensor 2 is inputted to an A/D converter 4 via a LPF 3, and crank pulses from a crank angle sensor 5 are inputted to a sampling signal generating circuit 7 via an input interface 6, so that a sampling signal is thereby introduced in response to these pulses. The A/D converter 4 outputs the output of the knock sensor 2 to a frequency analizer 8 while being synchronized with the aforesaid signal. The frequency analyzer analyzes spectral power for each frequency based on sampling data within the set period of observation, so that each maximum value of spectral power is set as each index value every cylinder. Meanwhile, a knock judging circuit 9 determines each knock judging reference based on the index values, it compares the aforesaid reference with each index value for this time, and when the aforesaid reference is found to be larger than the corresponding index value, it is judged that knocking has taken place, so that let a control circuit 11 make an ignition lead angle capacity small.

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 When performing ignition timing control of an internal combustion engine, knocking control is performed in which the ignition advance amount is increased within a range where knocking does not occur so as to obtain high output with low fuel consumption. In a typical prior art knocking control method, the vibration of the internal combustion engine is detected by an acceleration sensor or the like mounted on a cylinder block of the internal combustion engine, and the detected output is filtered by a bandpass filter that filters only the frequency component due to knocking. After that, the presence or absence of knocking is determined by discriminating the level of the filtered output according to a predetermined knocking determination standard.

The knocking determination criterion is the knock sensor output detected during the period from when the piston of the cylinder in the ignition stroke is at top dead center until the piston of the cylinder in the next ignition stroke reaches top dead center. Is calculated by averaging the peak value of 1 to the previous value by a predetermined number of data.

[0004]

In the above-mentioned prior art,
Due to the variation in the detection sensitivity of each cylinder of the knock sensor caused by the distance difference between the knock sensor and each cylinder,
For example, when the cylinder with high detection sensitivity is in the combustion stroke, it is always determined that knocking is present, and in the combustion stroke of the cylinder with low detection sensitivity, it may be determined that there is no knocking, and it is not possible to perform highly accurate determination There's a problem. Further, the output level of the knock sensor also greatly changes depending on the rotation speed of the internal combustion engine. Therefore, erroneous determination may occur when the rotation speed changes abruptly due to sudden acceleration or the like.

An object of the present invention is to provide a knocking control method and device capable of detecting knocking with high accuracy.

[0006]

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. An analysis is performed, and from the spectrum distribution of the analysis result, a value calculated based on the spectrum power over the observation period is set as an index value, and the cylinder to which the index value corresponds in response to the output of the crank angle sensor. Is determined, and a knocking determination standard is created by filtering the index value for each of a plurality of cylinders from the determination result, and knocking determination is performed based on the index value and the knocking determination standard, and the determination result is obtained. Is a knocking control method characterized in that the ignition advance angle is controlled in accordance with.

Further, according to the present invention, in response to the output of the crank angle sensor, the 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 plurality of frequency bands that may include a signal component indicating the occurrence of knocking are preset over the observation period, and within each frequency band, The value calculated based on the spectrum power of the is set as an index value, and the index value is filtered for each of the frequency bands to create a knocking determination standard,
A knocking control method is characterized in that knocking determination is performed from each index value and a corresponding knocking determination reference, and the ignition advance angle is controlled in accordance with the determination result.

Further, according to the present invention, a knocking observation period is set at a predetermined timing between the top dead centers of the pistons in response to the output of the crank angle sensor, and the frequency of the knock sensor output is analyzed during the observation period. From the spectrum distribution of the analysis result, set the value calculated based on the spectrum power over the observation period to the index value,
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 one of a plurality of predetermined rotational speed bands the detection result belongs to, and from the determination result, each rotational speed band is determined. The knocking control is characterized in that a knocking determination standard is created by filtering the index value in the above, a knocking determination is performed from the index value and the knocking determination standard, and the ignition advance angle is controlled according to the determination result. Is the way.

Further, according to the present invention, in response to the output of the crank angle sensor, the 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 plurality of frequency bands that may include a signal component indicating the occurrence of knocking are preset over the observation period, and within each frequency band, The index value is set to a value calculated based on the spectrum power of, and in response to the output of the crank angle sensor, the cylinder corresponding to each index value is determined and the rotation speed of the internal combustion engine is detected. , Which of the plurality of rotation speed bands the detection result belongs to is determined, and based on the determination results, the index value of each frequency band is determined for each rotation of each cylinder. It is characterized in that a knocking determination standard is created by filtering for each frequency band, knocking determination is performed from the index values and the corresponding knocking determination standard, and the ignition advance angle is controlled according to the determination result. This is a knocking control method.

Furthermore, the present invention is characterized in that the index value is multiplied by a predetermined coefficient.

Further, the present invention is characterized in that a predetermined increment is added to the index value.

Furthermore, the present invention is characterized in that the index value is multiplied by a predetermined coefficient and a predetermined increment is added.

Further, the present invention is characterized in that at least one of the coefficient and the increment is changed for each cylinder.

Furthermore, the present invention is characterized in that at least one of the coefficient and the increment is changed for each frequency band.

Further, the present invention is characterized in that at least one of the coefficient and the increment is changed for each rotational speed band.

Furthermore, the present invention is characterized in that at least one of the changing coefficient and the increment is stored as a map.

Further, the present invention is characterized in that at least one of a coefficient and an increment stored in the map is interpolated and obtained in accordance with the detected rotation speed.

Furthermore, the present invention further comprises 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. Based on the setting means, the cylinder discriminating means that discriminates the cylinder corresponding to the index value in response to the output of the crank angle sensor, and the discrimination result of the discriminating means, the index value is filtered for each of a plurality of cylinders. Judgment standard creating means for processing and creating a knocking judgment standard, and knocking judgment based on the index value and the knocking judgment standard, A knock control apparatus characterized by results in corresponding and a control means for controlling the spark advance.

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. From the analysis result of the analysis means for performing frequency analysis of the output from the knock sensor in the knocking observation period set between the predetermined timings between the dead points, and the analysis result of the analyzing means, the occurrence of knocking is represented over the observation period. Index value setting means for obtaining an index value for each of a plurality of frequency bands that may include a signal component, and determination standard creating means for filtering the index value for each frequency band to create a knocking determination standard. And a knocking determination based on the index value and the knocking determination standard, and a control hand that controls the ignition advance angle according to the determination result. A knock control apparatus which comprises and.

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, detecting the rotational speed of the internal combustion engine in response to the output of the crank angle sensor,
From the detection result, a rotation speed determination unit that determines which one of a plurality of rotation speed bands to which the rotation speed band belongs in advance, and from the determination result of the rotation speed determination unit, the index value is filtered for each rotation speed band. And a knocking judgment reference based on the index value and the knocking judgment reference, and control means for controlling the ignition advance angle according to the judgment result. Is a knocking control device.

[0021]

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. On the other hand, in response to the output of the crank angle sensor, the cylinders in the combustion stroke are discriminated, and the calculated index values are aggregated for each cylinder. For example, when the internal combustion engine has four cylinders, the index value of this time is The index value before 4, the index value before 8, and so on are totaled. In the tabulation, for example, the value obtained by multiplying the previous knocking determination standard for that cylinder by 7 is added with the index value of this time to obtain 8
Filtering is performed by dividing by. The filter processing result obtained in this way is set as the knocking determination standard for this time, and the knocking determination standard is compared with the index value this time. When the index value is large, it is determined that knocking has occurred and ignition is advanced. The angular amount is controlled to be small.

Further, according to the present invention, there is a possibility that the signal component indicating occurrence of knocking is included, for example, 7k.
Hz, 11 kHz, 13 kHz, 15 kHz and 19
A plurality of frequency bands are set in advance with a frequency such as kHz as the center frequency. In each of the set frequency bands, for example, the maximum value of the spectrum power is set as the index value. The index determination values thus obtained are aggregated for each frequency band and filtered to create a knocking determination standard, and the knocking determination is performed by comparing the knocking determination standard with the index value.

Furthermore, according to the present invention, the index value obtained from the spectrum distribution of the analysis result of the frequency analysis during the knocking observation period is preset from the rotational speed of the internal combustion engine obtained from the output of the crank angle sensor. A knocking determination standard is created by aggregating each of the plurality of rotation speed bands corresponding to each other and performing a filtering process.

Therefore, as described above, the index values are aggregated for each cylinder of the internal combustion engine or for each knocking frequency band or each rotational speed band, and the knocking criterion is set by performing the filtering process and setting the knocking determination standard. It is possible to perform a highly accurate knocking determination by compensating for the variation in the detection sensitivity that changes in accordance with the difference in distance or the rotational speed of the internal combustion engine.

Further, preferably, each index value is multiplied by a predetermined coefficient, or a predetermined increment is added, and these coefficients and increments are added to each cylinder,
By varying for each knocking frequency band or for each rotational speed band, it is possible to compensate for variations in detection sensitivity and offsets, and perform more accurate knocking determination.

Further preferably, at least one of the coefficient and the increment is stored in a memory in advance as a map, and these coefficient and increment are interpolated from the detected rotational speed. Good.
As a result, even for continuously changing rotation speed,
The coefficient or increment can be calculated with high accuracy with a small amount of data.

According to the present invention, a piezoelectric element or the like is used for the knocking determination as described above.
With a knock sensor that can be attached to a cylinder block,
A crank angle sensor for detecting the rotation 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 cylinder to which the obtained index value corresponds. Cylinder discriminating means to be performed, and from the discrimination result of the cylinder discriminating means, a judgment criterion creating means for creating a knocking judgment criterion by filtering the index value for each cylinder is provided, and the obtained index value and knocking judgment criterion are set. Based on the above, the control means makes the knocking determination based on the determination result, and controls the ignition advance angle according to the determination result.

Further, according to the present invention, when performing knocking determination, the knock sensor, the crank angle sensor, the analyzing means, and the signal component representing the knocking determination over the observation period from the analysis result of the analyzing means. Is provided by providing index value setting means for obtaining an index value for each of a plurality of frequency bands that may include, and judgment criterion creating means for filtering the index value to create a knocking judgment criterion. The control means performs knocking determination based on the index value and the knocking determination standard.

According to the invention, the knock sensor, the crank angle sensor, the analyzing means, the index value setting means, and the rotational speed of the internal combustion engine are detected in response to the outputs of the crank angle sensor, Knocking by filtering the index value for each rotation speed band from the detection result of the rotation speed determination unit and the rotation speed determination unit that determines which one of the plurality of rotation speed bands is determined from the detection result Judgment criterion creating means for creating a judgment criterion is provided, and the control means makes knocking judgment based on the index value and the knocking judgment criterion.

[0031]

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 transformation method in synchronization with the sampling signal. , And outputs the analysis result to the knocking determination circuit 9. As will be described later, the knocking determination circuit 9 uses the knocking frequency created based on the outputs of the frequency analyzer 8 and the cylinder determination circuit 10, the knocking frequency band width and the signal level to be filtered in order to pass only the knocking signal. Based on a knocking determination standard V that determines a knocking signal, it is determined whether knocking has occurred, and the determination result is derived to a control circuit 11 realized by a microcomputer or the like.

In relation to 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 analyzes the spectrum power at each of a plurality of frequencies, as shown in FIG. 3, based on all the sampling data in the observation period W1. In response to the discrimination output from the cylinder discrimination circuit 10 corresponding to the crank pulse shown in FIG. 2 (2), the knocking discrimination circuit 9 first discriminates the cylinder of the frequency analysis result as shown in FIG. 2 (3). To do. Next, in the analysis result for each cylinder, the maximum values P1, P2, P3, P4 of the spectrum power (hereinafter, indicated by reference numeral P when collectively referred to) are index values as shown in FIG. It is set to S1, S2, S3, S4 (hereinafter referred to as a reference symbol S when collectively referred).

In this embodiment, the distance between the top dead centers is 180.
Although it is a 4-cylinder internal combustion engine with ° CA, 1
In the case of a 6-cylinder internal combustion engine having a top dead center every 20 ° CA, six index values S are also set. 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 knocks assigned to the respective cylinders are provided. The output of each sensor 2 may be subjected to frequency analysis.

From the index value S, the knocking determination circuit 9 determines, for example, the previous knocking determination standard as V (i-1).
Then, as shown in Expression 1, 1 / is added to the index value Si of this time.
8 is weighted to obtain the knocking determination standard V of this time.

V = {V (i-1) × 7 + Si} / 8 (1) The knocking determination circuit 9 determines the knocking determination criteria V1 to V4 for each cylinder and the index values S1 to S4 of this time.
When the index values S1 to S4 are large, it is determined that knocking has occurred, and the control circuit 1
The ignition advance amount is reduced to 1. In this way, the ignition timing control corresponding to the output of the knock sensor 2 is performed.

FIG. 4 is a flow chart for explaining a concrete index value setting operation in each cylinder. Step m
At 1, 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 (fn-f0) when the analysis target frequency is f0 to fnHz and the resolution of the frequency analyzer 8 is fdHz.
It is an integer value of / fd.

At step m2, it is judged whether or not the comparison of the spectrum powers for all the frequencies is completed. If so, the operation is terminated, and if not so, the routine proceeds to step m3. In step m3, the spectrum power Pi of the i-th frequency fi is read, and in step m4 the maximum value P up to that time and the spectrum power Pi of this time are compared, and the spectrum power Pi of this time is read.
Is larger, the maximum value P is updated to the spectrum power Pi of this time in step m5, and then step m6
Move to step m6, otherwise move directly to step m6.
In step m6, 1 is added to the count value i to update it, and then the process returns to step m2. In this way, the maximum value P of the spectrum power Pi is searched over the frequencies f0 to fn, and the searched maximum value P is set as the index value S.

As described above, in the knocking control method according to the present invention, the frequency analysis result of the vibration detected by the knock sensor 2 is filtered for each cylinder generating the vibration, that is, in the ignition stroke, and knocking is performed. Since the determination reference V is obtained, it is possible to perform highly accurate knocking determination by compensating for variations in detection sensitivity due to the distance difference between the knock sensor 2 and each cylinder.

In the above embodiment, the maximum value P of the spectrum power is calculated from the spectrum distribution of the frequency analysis result.
Is set to the index value S, but as another embodiment of the present invention, as shown in FIG. 3, the frequency f (i−, which is adjacent to the frequency fi which becomes the maximum value P is added to the maximum value P.
The index value S may be set to a value obtained by adding the spectrum powers of 1) and f (i + 1).

FIG. 5 is a diagram for explaining the concept of a knocking determination method according to another embodiment of the present invention. This embodiment is similar to the above-described embodiment, and FIGS. 5 (1) to 5 (4) correspond to FIGS. 2 (1) to 2 (4), respectively. In this embodiment, when the knocking determination standard V is obtained from the respective index values S obtained by discriminating the frequency analysis cylinder for each cylinder, mutually different coefficients α1, α2, α3 for each cylinder.
α4 (hereinafter referred to as a reference symbol α when collectively referred to) is multiplied.

Therefore, as shown by 4 in FIG. 5 (4), for example, the coefficient α2 is set in the order of the second cylinder, the first cylinder, the fourth cylinder, and the third cylinder in the descending order of the detection sensitivity of the knock sensor 2. , Α1, α4, α3 are 1, 1.5, 1.
It is set to 8 and 2. This makes it possible to further compensate for variations in the detection sensitivity and improve the determination accuracy.

FIG. 6 is a diagram for explaining the concept of a knocking determination method according to still another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIG.
(1) to FIG. 6 (4) are shown in FIGS. 5 (1) to 5 (4), respectively.
It corresponds to. It should be noted that in this embodiment, the filter processing result of the index value S includes increments β1, β2, β3, β4 which are different from each other for each cylinder.
) Is added to obtain the knocking determination standard V. In this way, variations in sensor sensitivity may be compensated.

FIG. 7 is a diagram for explaining the concept of the knocking determination method of another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIG. 5 and FIG. (1) to FIG. 7 (4) are shown in FIGS. 5 (1) to 5 respectively.
This corresponds to (4) and FIGS. 6 (1) to 6 (4).
In this embodiment, the filter result of the index value S is multiplied by the coefficient α and the increment β is added. In this way, the variation in sensor sensitivity may be compensated with higher accuracy.

In each of the embodiments shown in FIGS. 5 to 7, the coefficient α and the increment β are set to different values for each cylinder. However, for example, there are differences in the type and specifications of the internal combustion engine. In the corresponding case, or for compensating the offset of the knock sensor 2, for example, the same value may be used. In this way, the versatility can be improved by compensating for the difference in the types and specifications of the internal combustion engine or the variation in the performance of the knock sensor 2.

FIG. 8 is a diagram for explaining the concept of a knocking determination method according to still another embodiment of the present invention. The output of the knock sensor 2 shown in FIG.
The frequency is analyzed as shown in (2). In this embodiment, for example, 7 kHz, 11
In FIG. 8 (2), reference numerals F1, F2, F3, F4, and F5 (collectively referred to as "generic frequencies", centering on frequencies that may include signal components representing the occurrence of knocking, such as kHz, 13 kHz, 15 kHz, and 19 kHz. Indicates a plurality of frequency bands in advance, and as shown in FIG. 8C, the maximum value Pf1 of the spectrum power in each frequency band F is set.
To Pf5 are set to the index values Sf1 to Sf5, respectively. From each index value Sf1 to Sf5, knocking determination criterion V
In determining f1 to Vf5, in this embodiment, as in the embodiment shown in FIG. 7, the coefficients αf1 to αf5 are multiplied for each frequency band F, and the increment β is obtained.
f1 to βf5 are added. Note that, as in the above-described embodiment, multiplication or increments βf1 to βf of the coefficients αf1 to αf5 are performed.
Either one of the additions of 5 may be performed. Further, the coefficients αf1 to αf5 and the increments βf1 to βf5 may be set to constant values.

In this way, weighting can be performed for each frequency band F, and the signal levels of knocking signal components appearing in each frequency band F can be averaged to facilitate comparison of the analysis results of each frequency band F. Further, it is possible to reliably detect knocking signal components having different frequencies due to differences in vibration modes such as the number of knocking locations in the cylinder.

FIG. 9 is a block diagram showing the electrical construction of an ignition timing control device 21 according to another embodiment of the present invention. This embodiment is similar to and corresponds to the embodiment shown in FIG. The parts have the same reference numerals. In this embodiment, the crank pulse from the crank angle sensor 5 is also input to the rotation speed determination circuit 20. Rotational speed discrimination circuit 20
Detects the rotational speed of the internal combustion engine from the cycle W0 of the crank pulse shown in FIG. 10 (2), and the rotational speed is determined in advance in a plurality of rotational speed bands N1, N2, ... (Indicated by (4)) is discriminated, and the coefficient α and the increment β are changed in accordance with the discrimination result as shown in FIG. 10 (4).

That is, the knock sensor output shown in FIG. 10 (1) is changed to the value shown in FIG. 10 (3) within the observation period W1 set corresponding to the crank pulse shown in FIG. 10 (2).
As shown by, the frequency is analyzed to determine the cylinder, and the index value S is obtained from the analysis result. These index values S
After filtering, the knocking determination reference V is obtained by multiplying the coefficient α and adding the increment β as in the embodiment shown in FIG. As shown in Table 1, the coefficient α and the increment β are preset for each rotation speed band N of the internal combustion engine and stored as a map, and the rotation speed of the internal combustion engine detected from the cycle W0 of the crank pulse. The coefficient α and the increment β are determined depending on which of these rotational speed bands N is in.

[0054]

[Table 1]

In this way, even if the output level of the knock sensor 2 greatly changes depending on the rotation speed, it is possible to compensate for them and to easily perform knocking determination.

It should be noted that the coefficient α and the increment β are not changed for each rotation speed band N as described above, but sample values corresponding to a plurality of rotation speeds are set in advance, and the actually detected rotation speeds are set. When is an intermediate value of these sample values, a sample value close to the intermediate value may be interpolated. In this case, the coefficient α and the increment β can be finely set according to the continuously changing rotation speed.

As another embodiment of the present invention, the rotation speed band N may be determined and the frequency band F shown in FIG. 8 may be determined.
Also, as shown in Table 2, the cylinder speed determination may be performed in addition to the determination of the rotation speed band N and the frequency band F.

[0058]

[Table 2]

[0059]

As described above, according to the present invention, the index value is aggregated for each cylinder of the internal combustion engine, or for each knocking frequency band or each rotational speed band, and the knocking criterion is set by performing the filtering process. A highly accurate knocking determination can be performed by compensating for the difference in distance between each cylinder and the knock sensor, or the variation in the detection sensitivity that changes corresponding to the rotation speed of the internal combustion engine.

Further, preferably, each index value is multiplied by a predetermined coefficient, or a predetermined increment is added, and these coefficients and increments are set for each cylinder.
By varying for each knocking frequency band or for each rotational speed band, it is possible to compensate for variations in detection sensitivity and offsets, and perform more accurate knocking determination.

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

FIG. 6 is a diagram for explaining the concept of a knocking determination method according to still another embodiment of the present invention.

FIG. 7 is a diagram for explaining the concept of a knocking determination method according to another embodiment of the present invention.

FIG. 8 is a diagram for explaining the concept of a knocking determination method according to still another embodiment of the present invention.

FIG. 9 is a block diagram showing an electrical configuration of 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. 10 is a diagram for explaining the concept of the knocking determination method of the embodiment shown in FIG.

FIG. 11 is a diagram for explaining the concept of a knocking determination method according to still another embodiment of the present invention.

[Explanation of symbols]

 1, 21 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 (15)

[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, set the value calculated based on the spectrum power over the observation period to the index value, and in response to the output of the crank angle sensor, determine the cylinder to which the index value corresponds, and the determination result From each of a plurality of cylinders to create a knocking determination standard by filtering the index value, perform knocking determination based on the index value and the knocking determination standard, the ignition advance corresponding to the determination result. A knocking control method characterized by controlling. 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, over the observation period, preset a plurality of each frequency band that may contain a signal component representing the occurrence of knocking, for each of the frequency band, the spectrum power in the frequency band A value calculated based on the above is set as an index value, a knocking determination standard is created by filtering the index value for each of the frequency bands, and a knocking determination is made from the knocking determination standard corresponding to each of the index values. A knocking control method, wherein the ignition advance angle is controlled in accordance with the determination result. 3. 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 the frequency of the knock sensor output is analyzed during the observation period. From the spectrum distribution, a value calculated based on the spectrum power over the observation period is set as an index value, the rotation speed of the internal combustion engine is detected in response to the output of the crank angle sensor, and the detection result is predetermined. It is determined which of the plurality of rotation speed bands belongs to, and a knocking determination standard is created by filtering the index value for each of the rotation speed bands from the determination result, and from the index value and the knocking determination standard. A knocking control method characterized by performing knocking determination and controlling an ignition advance angle according to the determination result. 4. A knocking observation period is set at a predetermined timing between the top dead centers of the pistons in response to the output of the crank angle sensor, and the frequency of the output of the knock sensor is analyzed during the observation period. From the spectrum distribution, over the observation period, preset a plurality of each frequency band that may contain a signal component representing the occurrence of knocking, for each of the frequency band, the spectrum power in the frequency band The index value is set to a value calculated based on the above, and in response to the output of the crank angle sensor, the cylinder to which each of the index values corresponds is detected, and the rotation speed of the internal combustion engine is detected, and the detection is performed. It is determined which of the plurality of rotational speed bands the result belongs to, and from each of the determination results, the index value of each frequency band is determined for each rotational speed band of each cylinder. Knock control method filtered to create a knocking determination criterion, the performed knocking determination from the corresponding knock determination reference each index value, and controlling the spark advance in response to the determination result. 5. The knocking control method according to claim 1, wherein the index value is multiplied by a predetermined coefficient. 6. The knocking control method according to claim 1, wherein a predetermined increment is added to the index value. 7. The knocking control method according to claim 1, wherein the index value is multiplied by a predetermined coefficient and a predetermined increment is added. 8. The method according to claim 5, wherein at least one of the coefficient and the increment is changed for each cylinder.
7. The knocking control method according to any one of 7. 9. The knocking control method according to claim 5, wherein at least one of the coefficient and the increment is changed for each frequency band. 10. The knocking control method according to claim 5, wherein at least one of the coefficient and the increment is changed for each rotation speed band. 11. The knocking control method according to claim 8, wherein at least one of the changing coefficient and the increment is stored as a map. 12. The knocking control method according to claim 11, wherein at least one of a coefficient and an increment stored in the map is interpolated in accordance with the detected rotation speed. 13. 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, In response to the output of the crank angle sensor, a cylinder discriminating unit that discriminates a cylinder to which the index value corresponds, and based on the discrimination result of the discriminating unit, the index value is filtered for each of a plurality of cylinders and knocked. Judgment standard creating means for creating a judgment standard, and knocking judgment based on the index value and the knocking judgment standard, and corresponding to the judgment result. And a control unit for controlling the ignition advance angle. 14. 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 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, over the observation period,
Index value setting means for obtaining an index value for each of a plurality of frequency bands that may include a signal component representing the occurrence of knocking, and a knocking determination standard is created by filtering the index value for each frequency band. A knocking control device comprising: a judgment reference creating means for performing knocking judgment based on the index value and the knocking judgment reference; and a control means for controlling an ignition advance angle corresponding to the judgment result. . 15. 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, Rotational speed discriminating means for detecting the rotational speed of the internal combustion engine in response to the output of the crank angle sensor and discriminating to which of a plurality of predetermined rotational speed zones it belongs from the detection result; Determination criterion creating means for creating a knocking determination criterion by filtering the index value for each rotation speed band from the determination result of A knocking control device comprising: a control unit that performs knocking determination based on the index value and a knocking determination standard, and controls the ignition advance angle in accordance with the determination result.