JP2008096279A - Knock determination system for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve knock determination accuracy by reducing the influence due to the mechanical noise of an engine. <P>SOLUTION: A vibration waveform which hardly contains vibration components of mechanical noise, and wherein the intensity of vibration in the high frequency region of knocking is amplified, can be obtained by extracting the vibration components in the high-frequency region (frequency region where the output gain of a knock sensor 28 becomes larger, as the frequency becomes higher) from the output of the knock sensor 28. By focusing on this, a predetermined frequency band which is extracted from the output of the knock sensor 28 is set so as to contain both the frequency region (for example, a frequency region not lower than 20 kHz), where the output gain of the knock sensor 28 becomes larger as the frequency becomes higher, and the frequency region (for example, the frequency region that is not higher than 15 kHz) where the output gain of the knock sensor 28 becomes substantially constant, and the existence of a knocking is determined, on the basis of a vibration component in the predetermined frequency band. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a knock determination device for an internal combustion engine that determines the presence or absence of knocking based on the output of a vibration sensor that detects knocking vibration of the internal combustion engine.

  Generally, a knock determination device for an internal combustion engine has a knock sensor for detecting knocking vibration attached to a cylinder block of the internal combustion engine, and compares the peak value or integral value of the output (vibration waveform) of this knock sensor with a knock determination threshold value. Many of them are designed to perform knock determination.

  By the way, as shown in FIG. 5, for example, in a general knock sensor, the output gain is flat (almost constant) in a frequency region sufficiently lower than the resonance frequency, but the frequency is higher in a frequency region higher than that. It has an output characteristic that the output gain increases as it becomes higher (approaching the resonance frequency).

In order to perform knock determination without being affected by the change in the output gain of the knock sensor in consideration of the output characteristics of the knock sensor, it is described in Patent Document 1 (Japanese Patent Publication No. 7-113353). As described above, the vibration component in the frequency band where the output gain is flat is extracted from the output of the knock sensor with a filter such as a bandpass filter, and the vibration component in the extracted frequency band (frequency band where the output gain of the knock sensor is flat) is extracted. Some use it to make knock determinations.
Japanese Patent Publication No.7-113353 (first page, etc.)

  In recent years, new mechanical noise, such as injector drive noise in a direct injection engine and variable valve timing device, has increased, resulting in an increase in the conventional low frequency range (the output gain of the knock sensor is flat). In the knock determination using the vibration component in the frequency domain), it is becoming difficult to reduce the influence of mechanical noise.

  Therefore, the present inventors are researching a knock determination system that reduces the influence of mechanical noise using vibration components in a higher frequency range than before, but the following new problems were found in this research process did.

  If a general knock sensor tries to make a knock determination using a vibration component in a higher frequency range than before, the frequency region of the vibration component used for the knock determination approaches the resonance frequency of the knock sensor and the output gain is flat. It is no longer an area. Therefore, in order to perform knock determination using a vibration component in a frequency region where the output gain of the knock sensor is flat as in the technique of Patent Document 1, the resonance frequency of the knock sensor is increased and the output gain is flat. It is necessary to expand the frequency region to the high frequency side. However, in order to increase the resonance frequency of the knock sensor, it is necessary to newly design and develop a special knock sensor in which a device such as a thin vibration element is thinned, and an increase in cost is inevitable. In addition, even if a knock sensor with a high resonance frequency can be realized by making the vibration element thinner, problems such as impaired durability or reduced output in all areas and weakening to electrical noise. May occur.

  The present invention has been made in consideration of such circumstances. Therefore, the object of the present invention is to reduce the influence of mechanical noise without increasing the resonance frequency of the vibration sensor, and to detect knocking. An object of the present invention is to provide a knock determination device for an internal combustion engine that can improve accuracy.

  To achieve the above object, a first aspect of the invention relates to a vibration sensor for detecting knocking vibration of an internal combustion engine, a filter means for extracting a vibration component in a predetermined frequency band from an output of the vibration sensor, and the filter means. In the knock determination device for an internal combustion engine, which includes knock determination means for determining the presence or absence of knocking based on a vibration component in a predetermined frequency band extracted from the output of the vibration sensor by the filter, the predetermined frequency extracted from the output of the vibration sensor by the filter means The band is set so as to include a frequency region in which the output gain of the vibration sensor increases as the frequency increases.

  In general, mechanical noise hardly occurs in a high-frequency region (for example, a frequency region of 20 kHz or higher, and a frequency region in which an output gain increases as the frequency increases in a general vibration sensor). On the other hand, knocking vibration occurs even in the high frequency region. However, the knocking vibration generated in the high frequency region is a low frequency region (for example, a frequency region of 15 kHz or less, and a frequency region where an output gain is flat in a general vibration sensor. In many cases, the vibration intensity is small compared to the knocking vibration generated in (1). Therefore, if a vibration component in a high frequency region (a frequency region in which the output gain of the vibration sensor increases as the frequency increases) is extracted from the output of the vibration sensor, vibrations in the high frequency region of knocking that hardly contain mechanical noise components are extracted. A vibration waveform with an amplified intensity can be obtained.

  Therefore, as in the present invention, the predetermined frequency band extracted from the output of the vibration sensor is set so as to include a frequency region in which the output gain of the vibration sensor increases as the frequency increases, and the vibration component of the predetermined frequency band is set as the vibration component. If knock determination is performed based on this, the influence of mechanical noise can be reduced, and the accuracy of knock determination can be improved. Moreover, since it is not necessary to increase the resonance frequency of the vibration sensor (expanding the frequency region where the output gain is flat to the high frequency side), the conventional general vibration sensor can be used as it is, and the cost, durability, Problems such as electrical noise can also be solved.

  In this case, as in claim 2, the vibration sensor has an output characteristic in which the output gain becomes substantially constant in the frequency region from 5 kHz to 15 kHz, and the output gain increases as the frequency increases in the frequency region higher than 15 kHz. In the system, the predetermined frequency band extracted from the output of the vibration sensor by the filter means may be set so as to include both the frequency region of 15 kHz or less and the frequency region of 20 kHz or more. In this way, both the frequency region where the output gain of the vibration sensor is substantially constant (frequency region of 15 kHz or less) and the frequency region where the output gain of the vibration sensor increases as the frequency increases (frequency region of 20 kHz or more). The knock determination can be performed using the vibration component in the frequency domain, and the knock determination accuracy can be improved.

  Furthermore, as in claim 3, vibration components of a plurality of frequency bands are extracted from the output of the vibration sensor, and at least one of the frequency bands is set to include both a frequency region of 15 kHz or less and a frequency region of 20 kHz or more. You may do it. Since vibration specific to knocking occurs in multiple frequency bands, if vibration components in multiple frequency bands are extracted from the output of the vibration sensor, only vibration components in the frequency band in which vibration specific to knocking occurs are extracted. Therefore, knocking vibration components can be extracted while removing noise vibration components.

  Further, the knock determination may be performed by determining whether knocking is present or not using a peak value or an integrated value (area) of the vibration waveform extracted from the output of the vibration sensor, as in claim 4. If the peak value or integral value of the vibration waveform extracted from the output of the vibration sensor is used, it is possible to evaluate the vibration intensity and accurately determine the presence or absence of knocking.

  Further, as in claim 5, knocking is performed using a comparison result between a vibration waveform extracted from the output of the vibration sensor and a vibration waveform stored in advance, and a peak value or an integral value of the vibration waveform extracted from the output of the vibration sensor. It may be determined whether or not there is. In this way, even if noise and knocking cannot be distinguished only by the peak value or integral value (that is, vibration intensity information) of the vibration waveform extracted from the output of the vibration sensor, the vibration waveform extracted from the output of the vibration sensor Noise and knocking can be accurately distinguished based on a comparison result with a vibration waveform stored in advance (for example, an ideal knock waveform representing a knock-specific waveform).

  By the way, since a general vibration sensor has an output characteristic that an output gain changes suddenly near a resonance frequency, it is difficult to directly use a vibration component near the resonance frequency in the output of the vibration sensor for knock determination. .

  Therefore, as described in claims 6 and 7, after performing processing for suppressing sudden changes in the resonance frequency of the vibration sensor and the output gain in the vicinity thereof, a predetermined frequency band (for example, a frequency region of 20 kHz or more is included from the output of the vibration sensor). (Frequency band) vibration component may be extracted. By controlling the sudden change in the output gain near the resonance frequency of the vibration sensor, the output characteristics of the vibration sensor are adjusted to a flat output characteristic that gradually increases the output gain to the high frequency region near the resonance frequency. Therefore, the output of the vibration sensor can be used for knock determination up to a high frequency region near the resonance frequency.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 15 whose opening is adjusted by the motor 10 and a throttle opening sensor 16 for detecting the opening (throttle opening) of the throttle valve 15 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 17 is provided on the downstream side of the throttle valve 15, and an intake pipe pressure sensor 18 for detecting the intake pipe pressure is provided in the surge tank 17. The surge tank 17 is provided with an intake manifold 19 for introducing air into each cylinder of the engine 11, and a fuel injection valve 20 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 19 of each cylinder. Yes. A spark plug 21 is attached to each cylinder of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each spark plug 21.

  Further, the engine 11 is provided with an intake side variable valve timing device 31 that varies the valve timing (opening / closing timing) of the intake valve 29 and an exhaust side variable valve timing device 32 that varies the valve timing of the exhaust valve 30. Yes.

  On the other hand, the exhaust pipe 22 of the engine 11 is provided with a catalyst 23 such as a three-way catalyst that purifies the exhaust gas, and an exhaust gas sensor that detects the air-fuel ratio or rich / lean of the exhaust gas upstream of the catalyst 23. 24 (air-fuel ratio sensor, oxygen sensor, etc.) are provided.

  The cylinder block of the engine 11 includes a cooling water temperature sensor 25 that detects the cooling water temperature, a knock sensor 28 (vibration sensor) that detects knocking vibration, and a pulse each time the crankshaft of the engine 11 rotates a predetermined crank angle. A crank angle sensor 26 for outputting a signal is attached. Based on the output signal of the crank angle sensor 26, the crank angle and the engine speed are detected.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 27. The ECU 27 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby determine the fuel injection amount of the fuel injection valve 20 according to the engine operating state. The ignition timing of the spark plug 21 is controlled.

  By the way, as shown in FIG. 2, the knock sensor 28 has a flat (almost constant) output gain in a frequency region sufficiently lower than its resonance frequency (for example, a frequency region from 5 kHz to 15 kHz). In a high frequency region (for example, a frequency region higher than 15 kHz), the output gain is increased as the frequency becomes higher (approaching the resonance frequency). Further, in the region from 15 kHz to 25 kHz, the output gain increases almost in proportion to the frequency, and the output gain in the vicinity of 25 kHz is 1.5 times or more the output gain in the vicinity of 15 kHz.

  Further, as shown in FIG. 3A, generally, mechanical noise hardly occurs in a high frequency region (for example, a frequency region where the output gain of the knock sensor 28 increases as the frequency increases in a frequency region of 20 kHz or higher). . On the other hand, knocking vibration occurs even in the high frequency region, but knocking vibration that occurs in the high frequency region is knocking that occurs in a low frequency region (for example, a frequency region where the output gain of knock sensor 28 is flat in a frequency region of 15 kHz or less). The vibration strength is often smaller than the vibration.

  Therefore, if a vibration component in a high frequency region (a frequency region in which the output gain of the knock sensor 28 increases as the frequency increases) is extracted from the output of the knock sensor 28, as shown in FIG. It is possible to obtain a vibration waveform that contains almost no components and amplifies the vibration intensity in the high frequency region of knocking.

  Focusing on this point, in this embodiment, the predetermined frequency band extracted from the output of the knock sensor 28 is set to a frequency region of 5 kHz to 25 kHz, for example, so that the output gain of the knock sensor 28 becomes flat. (Frequency region of 15 kHz or less) and a frequency region (frequency region of 20 kHz or more) in which the output gain of the knock sensor 28 increases as the frequency increases, and the ECU 27 performs knock determination in FIG. By executing the program, a bandpass filter process for extracting a vibration component in a predetermined frequency band (for example, 5 kHz to 25 kHz) from the output of the knock sensor 28 is performed, and the predetermined band extracted from the output of the knock sensor 28 by this bandpass filter process. Determine knocking based on vibration component of frequency bandThereby, the influence of mechanical noise is reduced and the knock determination accuracy is improved.

Hereinafter, the processing content of the knock determination program of FIG. 4 executed by the ECU 27 will be described.
The knock determination program shown in FIG. 4 is executed at a predetermined cycle while the ECU 27 is turned on, and serves as a knock determination means in the claims. When this program is started, first, in step 101, the vibration of the engine 11 is detected by reading the output of the knock sensor 28. This vibration detection is performed in a predetermined section of the combustion stroke (for example, a section from top dead center to 90 ° C. after top dead center).

  Thereafter, the process proceeds to step 102, where low-pass filter processing is performed on the output of the knock sensor 28, thereby performing processing for suppressing sudden changes in the resonance frequency of the knock sensor 28 and the output gain in the vicinity thereof. Thereby, as shown in FIG. 2, the output characteristic of the knock sensor 28 is adjusted to a substantially flat output characteristic in which the output gain gradually increases up to a high frequency region near the resonance frequency.

Thereafter, the process proceeds to step 103, and the vibration component in the predetermined frequency band is extracted from the output of the knock sensor 28 after the low-pass filter process by performing the band-pass filter process on the output of the knock sensor 28 after the low-pass filter process. Here, the predetermined frequency band (that is, the pass band of the low-pass filter) is set, for example, in a frequency region from 5 kHz to 25 kHz, and a frequency region where the output gain of the knock sensor 28 is flat (a frequency region of 15 kHz or less) and a frequency Is set so as to include both the frequency region (frequency region of 20 kHz or more) in which the output gain of knock sensor 28 increases as the value increases.
The processing of these steps 102 and 103 serves as filter means in the claims.

  Thereafter, the process proceeds to step 104, and after a low pass filter process and a band pass filter process for each predetermined crank angle (for example, 5 ° C. A) in a predetermined section (for example, a section from the top dead center to 90 ° C. after the top dead center). After calculating the integrated value obtained by integrating the output of the knock sensor 28 by the predetermined crank angle (for example, 5 ° C.), the process proceeds to step 105 and the integrated value (vibration waveform) of the output of the knock sensor 28 for each predetermined crank angle. The largest peak value P is calculated.

  Thereafter, the routine proceeds to step 106, where the integrated value (vibration waveform) for each predetermined crank angle of the output of the knock sensor 28 is normalized. Here, normalization refers to dividing the integrated value for each predetermined crank angle of the output of the knock sensor 28 by the peak value P, so that the vibration intensity is expressed in a dimensionless number (for example, a dimensionless number of 0 to 1). The process to represent. The normalization method is not limited to this. For example, the integrated value for each predetermined crank angle of the output of the knock sensor 28 may be divided by the integrated value at the peak position. This normalization makes it possible to compare the detected vibration waveform with a pre-stored ideal knock waveform (vibration waveform representing a knock-specific waveform) regardless of the vibration intensity, so that it can handle vibration intensity. Thus, it is not necessary to store a large number of ideal knock waveforms, and it is easy to create an ideal knock waveform.

  Thereafter, the process proceeds to step 107, and the shape correlation coefficient K representing the degree of coincidence between the detected vibration waveform (vibration waveform after normalization) and the ideal knock waveform is calculated as follows. First, a predetermined crank angle (for example, 5 ° C. A) in a state where the timing at which the vibration intensity is maximum in the detected vibration waveform (that is, the peak position) and the timing at which the vibration intensity is maximum in the ideal knock waveform are matched. Every time, the absolute value ΔS of the deviation between the detected vibration waveform and the ideal knock waveform is calculated.

Thereafter, the total sum ΣΔS of ΔS in a predetermined section (for example, the section from the top dead center to 90 ° C. after the top dead center) and the integrated value S of the ideal knock waveform in the predetermined section (that is, the area of the ideal knock waveform) are used. Then, the shape correlation coefficient K is calculated from the following equation.
K = (S−ΣΔS (I)) / S

  Thereby, the degree of coincidence (similarity) between the detected vibration waveform and the ideal knock waveform can be digitized and objectively determined. Further, by comparing the detected vibration waveform with the ideal knock waveform, it is possible to analyze whether or not the vibration is at the time of knocking from vibration behavior such as a vibration attenuation tendency.

  Thereafter, the process proceeds to step 108, where it is determined whether or not the shape correlation coefficient K is larger than a predetermined value. If it is determined in step 108 that the shape correlation coefficient K is equal to or smaller than the predetermined value (that is, the degree of coincidence between the detected vibration waveform and the ideal knock waveform is low), the process proceeds to step 111, where knocking is performed. It is determined that it has not occurred, and the ignition timing is advanced.

On the other hand, if it is determined in step 108 that the shape correlation coefficient K is larger than the predetermined value (that is, the degree of coincidence between the detected vibration waveform and the ideal knock waveform is high), the process proceeds to step 109. Using the peak value P of the integrated value for each predetermined crank angle of the output of the knock sensor 28, the shape correlation coefficient K, and the BGL (Back Ground Level), the knock intensity N is calculated by the following equation.
N = P × K / BGL
Here, BGL is a value representing the vibration intensity of the engine 11 in a state where knocking has not occurred in the engine 11.

  As a result, in addition to the degree of coincidence between the detected vibration waveform and the ideal knock waveform, it is possible to analyze in more detail whether the vibration of the engine 11 is vibration caused by knocking based on the vibration intensity. .

  Thereafter, the process proceeds to step 110, where it is determined whether or not the knock magnitude N is larger than the knock determination value. If it is determined at step 110 that the knock magnitude N is equal to or smaller than the knock determination value, the routine proceeds to step 111, where it is determined that knocking has not occurred, and the ignition timing is advanced.

  On the other hand, if it is determined at step 110 that the knock magnitude N is greater than the knock determination value, the routine proceeds to step 112 where it is determined that knocking has occurred and the ignition timing is retarded. Thereby, occurrence of knocking is suppressed.

  In the present embodiment described above, if the vibration component in the high frequency region (frequency region where the output gain of the knock sensor 28 increases as the frequency increases) is extracted from the output of the knock sensor 28, the vibration component of mechanical noise is almost included. Focusing on the characteristic that a vibration waveform obtained by amplifying the vibration intensity in the high frequency region of knocking can be obtained, a predetermined frequency band extracted from the output of the knock sensor 28 is set to an output gain of the knock sensor 28 as the frequency increases. Is set so as to include a frequency region where the frequency becomes large, and the knock determination is performed based on the vibration component of the predetermined frequency band, so that the influence of mechanical noise can be reduced and the knock determination accuracy can be improved. Can do. Moreover, since it is not necessary to increase the resonance frequency of the knock sensor 28 (expand the frequency region where the output gain is flat to the high frequency side), the conventional general knock sensor 28 can be used as it is, and the cost is reduced. While satisfying these requirements, problems such as durability and electrical noise can be solved.

  Further, in this embodiment, the predetermined frequency band extracted from the output of the knock sensor 28 is set so as to include both the frequency region of 15 kHz or less and the frequency region of 20 kHz or more. Knocking using vibration components in both the frequency region where the frequency becomes substantially constant (frequency region below 15 kHz) and the frequency region where the output gain of the knock sensor 28 increases as the frequency increases (frequency region above 20 kHz). The determination can be performed, and the knock determination accuracy can be further improved.

  In this embodiment, since the knock determination is performed using the peak value of the detected vibration waveform (the peak value of the integrated value for each predetermined crank angle of the output of the knock sensor 28), the vibration intensity is evaluated. Thus, the presence or absence of knocking can be accurately determined. It should be noted that knock determination may be performed using an integral value (area) instead of the detected peak value of the vibration waveform.

  Furthermore, in this embodiment, since the knock determination is performed using the shape correlation coefficient K representing the degree of coincidence between the detected vibration waveform and the ideal knock waveform, the peak value or the integrated value (that is, the vibration value) of the vibration waveform is determined. Even when noise and knocking cannot be distinguished only by intensity information), noise and knocking can be accurately distinguished by the shape correlation coefficient K.

  By the way, since the knock sensor 28 has an output characteristic that the output gain changes suddenly near the resonance frequency, it is difficult to directly use the vibration component near the resonance frequency in the output of the knock sensor 28 for the knock determination.

  In this regard, in the present embodiment, since the process for suppressing the sudden change in the output gain at the resonance frequency of the knock sensor 28 and in the vicinity thereof is performed, the output characteristics of the knock sensor 28 are output to the high frequency region near the resonance frequency. Therefore, the output of the knock sensor 28 can be used for knock determination up to a high frequency region near the resonance frequency.

  In the above embodiment, the vibration component of one frequency band (for example, 5 kHz to 25 kHz) is extracted from the output of the knock sensor 28. However, the vibration component of a plurality of frequency bands is extracted from the output of the knock sensor 28. The frequency range of 15 kHz or less and the frequency region of 20 kHz or more may be included in at least one of the frequency bands. Since vibration specific to knocking occurs in a plurality of frequency bands, if vibration components in a plurality of frequency bands are extracted from the output of the knock sensor 28, only the vibration component in the frequency band in which vibration specific to knocking occurs is extracted. Thus, knocking vibration components can be extracted while removing noise vibration components.

  In the above embodiment, the predetermined frequency band extracted from the output of the knock sensor 28 is divided into a frequency region where the output gain of the knock sensor 28 is substantially constant, and a frequency where the output gain of the knock sensor 28 increases as the frequency increases. Although both regions are set to be included, only the frequency region in which the output gain of knock sensor 28 increases as the frequency increases may be extracted from the output of knock sensor 28.

  Further, the frequency band extracted from the output of the knock sensor 28 may be appropriately changed according to the output characteristics of the knock sensor 28, the knock determination method, and the like. In short, the output gain of the knock sensor 28 increases as the frequency increases. What is necessary is just to set so that the frequency area | region which becomes large may be included.

  In the above embodiment, the present invention is applied to the intake port injection engine. However, the present invention may be applied to an in-cylinder injection engine or a dual injection engine provided with fuel injection valves in both the intake port and the cylinder. good.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is an output characteristic figure of a knock sensor. It is a figure for demonstrating the characteristic of knocking and mechanical noise. It is a flowchart which shows the flow of a process of a knock determination program. It is a figure for demonstrating the frequency area | region where the output gain of a knock sensor is flat.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 20 ... Fuel injection valve, 21 ... Spark plug, 22 ... Exhaust pipe, 27 ... ECU (filter means, knock determination means), 28 ... Knock sensor (Vibration sensor)

Claims (7)

A vibration sensor for detecting knocking vibration of the internal combustion engine, a filter means for extracting a vibration component of a predetermined frequency band from the output of the vibration sensor, and a vibration component of the predetermined frequency band extracted from the output of the vibration sensor by the filter means. In a knock determination device for an internal combustion engine comprising knock determination means for determining the presence or absence of knocking based on
The predetermined frequency band extracted from the output of the vibration sensor by the filter means is set to include a frequency region in which the output gain of the vibration sensor increases as the frequency increases. Judgment device. The vibration sensor has an output characteristic in which an output gain becomes substantially constant in a frequency region from 5 kHz to 15 kHz, and an output gain increases as the frequency increases in a frequency region higher than 15 kHz,
2. The internal combustion engine according to claim 1, wherein the predetermined frequency band extracted from the output of the vibration sensor by the filter means is set to include both a frequency region of 15 kHz or less and a frequency region of 20 kHz or more. Engine knock determination device.   The filter means is configured to extract vibration components of a plurality of frequency bands from the output of the vibration sensor, and to include both a frequency region of 15 kHz or less and a frequency region of 20 kHz or more in at least one of the frequency bands. The knock determination device for an internal combustion engine according to claim 2, wherein the knock determination device is an internal combustion engine.   4. The knock determination unit according to claim 1, wherein the knock determination unit determines the presence or absence of knocking using a peak value or an integral value of a vibration waveform extracted from the output of the vibration sensor by the filter unit. Knock determination device for internal combustion engine.   The knock determination means includes a comparison result between a vibration waveform extracted from the output of the vibration sensor by the filter means and a vibration waveform stored in advance, and a peak value of the vibration waveform extracted from the output of the vibration sensor by the filter means or 5. The knock determination device for an internal combustion engine according to claim 4, wherein the presence or absence of knocking is determined using the integrated value.   The filter means performs a process of extracting a vibration component of the predetermined frequency band from the output of the vibration sensor after performing a process of suppressing a sudden change in the output frequency at and near the resonance frequency of the vibration sensor. The knock determination device for an internal combustion engine according to any one of claims 1 to 5. A vibration sensor for detecting knocking vibration of the internal combustion engine, a filter means for extracting a vibration component of a predetermined frequency band from the output of the vibration sensor, and a vibration component of the predetermined frequency band extracted from the output of the vibration sensor by the filter means. In a knock determination device for an internal combustion engine comprising knock determination means for determining the presence or absence of knocking based on
The predetermined frequency band extracted from the output of the vibration sensor by the filter means is set to include a frequency region of 20 kHz or more,
The filter means performs a process of extracting a vibration component of the predetermined frequency band from the output of the vibration sensor after performing a process of suppressing a sudden change in the output frequency at and near the resonance frequency of the vibration sensor. A knock determination device for an internal combustion engine.

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