JP2008069752A - Method for specifying frequency - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately specify a frequency of vibration by knocking. <P>SOLUTION: The method for specifying the frequency includes a step (S104) for calculating SN ratio (1) in a state where the noise is generated in a knocking detection gate for each of the frequencies, a step (S114) for calculating SN ratio (2) in the state where the noise is not generated in the knocking detection gate for each of the frequencies, a step (S120) for calculating a ratio between the SN ratio (1) and the SN ratio (2) by dividing the SN ratio (1) by the SN ratio (2), and a step (S140) for specifying the frequency coinciding with the reference including that the ratio between the SN ratio (1) and the SN ratio (2) is near "1" in the frequency in the center of a frequency band of the vibration extracted in order to determine the presence of knocking. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for specifying a frequency, and more particularly to a technique for specifying a frequency of vibration to be extracted in order to determine the presence or absence of knocking.

  Conventionally, it is known that knocking occurs in an internal combustion engine. When knocking occurs, vibration specific to knocking occurs in the internal combustion engine. Therefore, in general, knocking is detected from the vibration intensity of the internal combustion engine. For example, when the intensity of vibration of the internal combustion engine is higher than a threshold value, it is determined that knocking has occurred. However, in an internal combustion engine, vibration occurs due to factors other than knocking. For example, vibration is generated by seating of an intake valve and an exhaust valve, piston slap, operation of an injector (particularly, in-cylinder injector), and operation by a fuel pump. The strength of the vibration caused by these parts is as high as the strength of the vibration caused by knocking. Therefore, it is difficult to accurately determine the presence or absence of knocking only from the vibration intensity. Therefore, a technique has been proposed in which knocking is detected based on a vibration intensity change pattern, that is, a vibration waveform.

  Japanese Patent Laying-Open No. 4-76249 (Patent Document 1) discloses a knocking detection device that detects the occurrence of knocking from a detection signal of engine vibration. A knocking detection device described in Patent Document 1 includes a vibration sensor attached to an engine body for detecting engine vibration, an intensity detection unit for detecting the intensity of a specific frequency component of a detection signal of the vibration sensor, and a detection signal of the vibration sensor. An intensity change detection unit for detecting the intensity change pattern of the specific frequency component, and a knock determination unit for determining the occurrence of knocking based on the detected intensity of the specific frequency component and the intensity change pattern.

According to the knocking detection device described in this publication, in addition to the intensity of the specific frequency component of the vibration sensor, a pattern of intensity change of the specific frequency component is used as information for knocking determination. Since the pattern of intensity change is not related to the absolute level of the detection signal, the accuracy of knocking detection can be improved even when the detection signal level is low as a whole, compared to the case where knocking detection is performed based only on the intensity.
Japanese Patent Laid-Open No. 4-76249 (Japanese Patent Publication No. 8-19890)

  When determining the presence or absence of knocking using the intensity of a specific frequency component, as in the knocking detection device described in Japanese Patent Application Laid-Open No. 4-76249, vibration due to knocking is prominent in the frequency component used for the knocking determination. It is necessary to specify the frequency that appears. However, there is a case where vibration due to the operation of the components of the internal combustion engine, that is, noise frequency is mixed with the frequency at which vibration due to knocking appears remarkably. If the presence or absence of knocking is determined based on such a frequency, the presence or absence of knocking may be erroneously determined. However, Japanese Patent Laid-Open No. 4-76249 does not describe how to distinguish between the frequency of only the vibration caused by knocking and the frequency where noise is mixed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a frequency specifying method that can accurately specify the frequency of vibration caused by knocking.

  The frequency specifying method according to the first aspect of the invention is a method for specifying the frequency of vibration extracted for determining the presence or absence of knocking. In this identification method, vibrations due to knocking occur at predetermined crank angle intervals, and vibrations due to the operation of predetermined parts provided in the internal combustion engine occur. A step of detecting the strength of the crankshaft at a predetermined crank angle interval, a state in which vibration due to knocking does not occur at a predetermined crank angle interval, and vibration due to operation of a predetermined component occurs. Detecting a second intensity of vibration of the internal combustion engine at a predetermined crank angle interval, calculating a first intensity and a first ratio of the second intensity for each frequency of the vibration, An internal combustion engine with vibration caused by knocking at a predetermined crank angle interval and no vibration caused by operation of a predetermined part. Detecting the third strength of the function at a predetermined crank angle interval, and no vibration due to knocking occurs at a predetermined crank angle interval, and vibration due to operation of a predetermined part is generated. And detecting a fourth intensity of the internal combustion engine at a predetermined crank angle interval, and calculating a third intensity and a second ratio of the fourth intensity for each frequency of vibration. And specifying the frequency of vibration to be extracted based on the result of comparing the first ratio and the second ratio for each frequency and the first ratio.

  According to the first aspect of the present invention, vibration due to knocking occurs at a predetermined crank angle interval and vibration due to operation of a predetermined component provided in the internal combustion engine occurs. The first intensity is detected at a predetermined crank angle interval. In a state in which vibration due to knocking does not occur at a predetermined crank angle interval and vibration due to operation of a predetermined component occurs, the second strength of vibration of the internal combustion engine is equal to a predetermined crank angle. Detected at intervals. A first ratio of the first intensity and the second intensity, that is, the SN ratio is calculated for each frequency of vibration. Further, the third strength of the internal combustion engine is set at a predetermined crank angle interval in a state where vibration due to knocking occurs at a predetermined crank angle interval and vibration due to operation of a predetermined component does not occur. Is detected. The fourth strength of the internal combustion engine is set at a predetermined crank angle interval in a state where no vibration due to knocking occurs at a predetermined crank angle interval and no vibration due to operation of a predetermined component occurs. Detected. A second ratio of the third intensity and the fourth intensity, that is, the SN ratio is calculated for each frequency of vibration. Accordingly, the first ratio in a state where vibration is generated by the operation of a predetermined part provided in the internal combustion engine and the second state in which vibration is not generated by the operation of a predetermined part provided in the internal combustion engine. Can be obtained for each frequency of vibration. The frequency at which the difference between the first ratio and the second ratio is small can be said to be a frequency at which vibration due to the operation of a predetermined component provided in the internal combustion engine does not occur. Further, the difference between the first intensity and the second intensity, that is, the frequency at which the first ratio is large can be said to be the frequency of vibration due to knocking. Therefore, the frequency of the vibration to be extracted is specified based on the result of comparing the first ratio and the second ratio for each frequency and the first ratio. As a result, it is possible to specify a frequency at which vibration due to the operation of a predetermined component provided in the internal combustion engine does not appear and vibration due to knocking appears. Therefore, it is possible to provide a frequency specifying method that can accurately specify the frequency of vibration caused by knocking.

  In addition to the configuration of the first invention, the frequency specifying method according to the second invention is obtained by integrating one of the first ratio and the second ratio for each of a plurality of frequency bands having the same width. The method further includes calculating. The step of identifying the frequency of vibration generated by knocking includes the frequency of vibration to be extracted based on the integration value in addition to the result of comparing the first ratio and the second ratio for each frequency and the first ratio. Including the step of identifying

  According to the second invention, an integrated value is calculated by integrating either the first ratio or the second ratio for each of a plurality of frequency bands having the same width. For example, when the first ratio or the second ratio is calculated so as to increase at a frequency at which vibration due to knocking occurs, vibration due to knocking appears in a frequency band having a large integral value compared to a frequency band having a small integral value. It can be said that the bandwidth is wide. The wider the band in which the vibration due to knocking appears, the easier it is to detect the vibration. Therefore, in order to select a frequency band in which a band in which vibration due to knocking appears is wide, in addition to the result of comparing the first ratio and the second ratio for each frequency and the first ratio, based on the integral value, The frequency of vibration to be extracted is specified. Thereby, it is possible to specify a frequency at which vibration due to knocking can be easily detected.

  In addition to the configuration of the first invention, the frequency specifying method according to the third invention is obtained by integrating any one of the first intensity and the third intensity for each of a plurality of frequency bands having the same width. The method further includes calculating. The step of identifying the frequency of vibration generated by knocking includes the frequency of vibration to be extracted based on the integration value in addition to the result of comparing the first ratio and the second ratio for each frequency and the first ratio. Including the step of identifying

  According to the third invention, an integral value obtained by integrating any one of the first intensity and the third intensity for each of a plurality of frequency bands having the same width is calculated. It can be said that the frequency band where the integral value is large has a wider band in which vibration due to knocking appears than the frequency band where the integral value is small. The wider the band in which the vibration due to knocking appears, the easier it is to detect the vibration. Therefore, in order to select a frequency band in which a band in which vibration due to knocking appears is wide, in addition to the result of comparing the first ratio and the second ratio for each frequency and the first ratio, based on the integral value, The frequency of vibration to be extracted is specified. Thereby, it is possible to specify a frequency at which vibration due to knocking can be easily detected.

  In the frequency specifying method according to the fourth invention, in addition to the configuration of the first invention, an integrated value obtained by integrating the ratio of the first ratio and the second ratio is calculated for each of a plurality of frequency bands having the same width. The method further includes a step. The step of identifying the frequency of vibration generated by knocking includes the frequency of vibration to be extracted based on the integration value in addition to the result of comparing the first ratio and the second ratio for each frequency and the first ratio. Including the step of identifying

  According to the fourth invention, an integral value obtained by integrating the ratio of the first ratio and the second ratio is calculated for each of a plurality of frequency bands having the same width. When the ratio of the first ratio and the second ratio is calculated so as to decrease at a frequency at which vibration is generated by the operation of a predetermined component provided in the internal combustion engine, the frequency band having a small integral value is an integral value. It can be said that the band in which the vibration due to the operation of the parts appears is wider than the frequency band where the Vibration due to the operation of a component can be a cause of erroneous determination when determining the presence or absence of knocking. Therefore, in order to exclude the frequency at which the vibration due to the operation of the component appears, the first ratio and the second ratio are extracted based on the integration value in addition to the result of comparing the first ratio and the second ratio for each frequency and the first ratio. The frequency of vibration is specified. Thereby, the frequency which excluded the vibration by operation of parts can be specified.

  In addition to the configuration of any one of the first to fourth inventions, the frequency specifying method according to the fifth invention is defined based on the same frequency as one of the first ratio and the second ratio. Further, each first integrated value is corrected based on a step of calculating a first integrated value integrated for each of a plurality of frequency bands having different widths, and a ratio of the width of each frequency band and a predetermined width. The method further includes a step of calculating a second integral value and a step of specifying a width of a frequency band of vibration to be extracted based on each second integral value.

  According to the fifth invention, a first integrated value obtained by integrating any one of the first ratio and the second ratio for each of a plurality of frequency bands having different widths, which is determined based on the same frequency. Calculated. Based on the width of each frequency band and a ratio of a predetermined width, a second integrated value obtained by correcting each first integrated value is calculated. For example, when the first ratio or the second ratio is calculated so as to increase at a frequency at which vibration due to knocking occurs, a frequency band with a large second integral value is compared with a frequency band with a small second integral value. It can be said that it includes more frequencies at which vibration due to knocking appears. Therefore, the frequency band width of the vibration to be extracted is specified based on each second integrated value. Thereby, the width of the frequency band including the frequency of the vibration caused by knocking can be specified.

  The frequency specifying method according to the sixth invention is determined based on the same frequency as one of the first intensity and the second intensity in addition to the configuration of any one of the first to fourth inventions. Further, each first integrated value is corrected based on a step of calculating a first integrated value integrated for each of a plurality of frequency bands having different widths, and a ratio of the width of each frequency band and a predetermined width. The method further includes a step of calculating a second integral value and a step of specifying a width of a frequency band of vibration to be extracted based on each second integral value.

  According to the sixth invention, there is provided a first integrated value obtained by integrating one of the first intensity and the second intensity for each of a plurality of frequency bands having different widths determined with reference to the same frequency. Calculated. Based on the width of each frequency band and a ratio of a predetermined width, a second integrated value obtained by correcting each first integrated value is calculated. It can be said that the frequency band in which the second integral value is large includes more frequencies at which vibration due to knocking appears than the frequency band in which the second integral value is small. Therefore, the frequency band width of the vibration to be extracted is specified based on each second integrated value. Thereby, the width of the frequency band including the frequency of the vibration caused by knocking can be specified.

  In the frequency specifying method according to the seventh invention, in addition to the configuration of any one of the first to fourth inventions, the first integrated value obtained by integrating the ratio of the first ratio and the second ratio is set to the same frequency. A step of calculating for each of a plurality of frequency bands having the same width, which is determined based on a reference, and a second value obtained by correcting each first integral value based on a ratio of the width of each frequency band and a predetermined width. The method further includes the step of calculating the integral value and the step of specifying the width of the frequency band of the vibration to be extracted based on each second integral value.

  According to the seventh invention, the first integrated value obtained by integrating the ratio of the first ratio and the second ratio is calculated for each of a plurality of frequency bands having the same width, which are determined based on the same frequency. . Based on the width of each frequency band and a ratio of a predetermined width, a second integrated value obtained by correcting each first integrated value is calculated. For example, when the ratio of the first ratio and the second ratio is calculated so as to decrease at a frequency at which vibration is generated by the operation of a predetermined component provided in the internal combustion engine, the frequency band in which the second integral value is large. Can be said to contain more frequencies at which vibrations due to the operation of the parts do not appear and vibrations due to knocking appear than in the frequency band where the second integral value is small. Therefore, the frequency band width of the vibration to be extracted is specified based on each second integrated value. Thereby, the width of the frequency band including the frequency of the vibration caused by knocking can be specified.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<First Embodiment>
A vehicle engine 100 will be described with reference to FIG. Engine 100 is an internal combustion engine that burns an air-fuel mixture of air sucked from air cleaner 102 and fuel injected from injector 104 by igniting with an ignition plug 106 in a combustion chamber.

  When the air-fuel mixture burns, the piston 108 is pushed down by the combustion pressure, and the crankshaft 110 rotates. The combusted air-fuel mixture (exhaust gas) is purified by the three-way catalyst 112 and then discharged outside the vehicle. The amount of air taken into engine 100 is adjusted by throttle valve 114.

  The engine 100 is controlled by an engine ECU (Electronic Control Unit) 200. Engine ECU 200 is connected to knock sensor 300, water temperature sensor 302, crank position sensor 306 provided opposite to timing rotor 304, throttle opening sensor 308, vehicle speed sensor 310, and ignition switch 312. ing.

  Knock sensor 300 is composed of a piezoelectric element. Knock sensor 300 generates a voltage due to vibration of engine 100. The magnitude of the voltage corresponds to the magnitude of the vibration. Knock sensor 300 transmits a signal representing a voltage to engine ECU 200. Water temperature sensor 302 detects the temperature of the cooling water in the water jacket of engine 100 and transmits a signal representing the detection result to engine ECU 200.

  The timing rotor 304 is provided on the crankshaft 110 and rotates together with the crankshaft 110. A plurality of protrusions are provided on the outer periphery of the timing rotor 304 at predetermined intervals. The crank position sensor 306 is provided to face the protrusion of the timing rotor 304. When the timing rotor 304 rotates, the air gap between the protrusion of the timing rotor 304 and the crank position sensor 306 changes, so that the magnetic flux passing through the coil portion of the crank position sensor 306 increases and decreases, and an electromotive force is generated in the coil portion. . Crank position sensor 306 transmits a signal representing the electromotive force to engine ECU 200. Engine ECU 200 detects the crank angle based on the signal transmitted from crank position sensor 306.

  Throttle opening sensor 308 detects the throttle opening and transmits a signal representing the detection result to engine ECU 200. Vehicle speed sensor 310 detects the number of rotations of a wheel (not shown) and transmits a signal representing the detection result to engine ECU 200. Engine ECU 200 calculates the vehicle speed from the rotational speed of the wheel. Ignition switch 312 is turned on by the driver when engine 100 is started.

  Engine ECU 200 performs arithmetic processing based on signals transmitted from each sensor and ignition switch 312, a map and a program stored in memory 202, and controls equipment so that engine 100 is in a desired operating state. .

  Based on the signal and crank angle transmitted from knock sensor 300, engine ECU 200 determines an engine in a predetermined knock detection gate (a section from a predetermined first crank angle to a predetermined second crank angle). 100 vibration waveforms (hereinafter referred to as vibration waveforms) are detected. As will be described later, the detected vibration waveform is compared with a knock waveform model created in advance to determine whether or not knocking has occurred. The knock detection gate in the present embodiment is from top dead center (0 degree) to 90 degrees in the combustion stroke. The knock detection gate is not limited to this.

  When knocking occurs in the cylinder of engine 100, the cylinder pressure resonates. Due to the resonance of the in-cylinder pressure, the cylinder block of the engine 100 vibrates. Therefore, the vibration of the cylinder block, that is, the frequency of vibration detected by the knock sensor 300 tends to be included in the in-cylinder pressure resonance frequency band.

  The in-cylinder pressure resonance frequency is a frequency corresponding to the resonance mode of the in-cylinder air column. Typical frequency bands in which specific vibrations appear at the time of knocking include frequency bands in the tangential first, second, third, fourth, and radial primary resonance modes.

  The theoretical in-cylinder pressure resonance frequency is calculated from the resonance mode, bore diameter, and sound velocity. FIG. 2 shows an example of the in-cylinder pressure resonance frequency in each resonance mode when the sound speed is constant and the bore diameter is changed from X to Y. As is apparent from FIG. 2, the in-cylinder pressure resonance frequency increases in the order of tangential primary, tangential secondary, radial primary, tangential tertiary, and tangential fourth order.

  The in-cylinder pressure resonance frequency shown in FIG. 2 is the in-cylinder pressure resonance frequency at the timing when knocking occurs. After the occurrence of knocking, the volume of the combustion chamber increases due to the lowering of the piston, so that the temperature and pressure in the combustion chamber decrease. Therefore, the speed of sound is reduced and the in-cylinder pressure resonance frequency is reduced. Therefore, as shown in FIG. 3, the peak component of the in-cylinder pressure frequency decreases as the crank angle increases from the top dead center (ATDC).

  The cylinder block vibrates due to resonance of the in-cylinder pressure having such characteristics. Therefore, in the ignition cycle in which knocking occurs, vibrations detected by knock sensor 300 include vibrations in the frequency band of the tangential primary resonance mode, vibrations in the frequency band of the tangential secondary resonance mode, and radial. The vibration of the primary frequency band, the vibration of the tangential third-order frequency band, and the vibration of the frequency band of the tangential fourth-order resonance mode are included.

  By the way, as shown in FIG. 3, the frequency band of the tangential primary resonance mode includes the resonance frequency of the engine 100. Therefore, as shown in FIG. 4, mechanical vibration of engine 100 itself appears in the frequency band of the tangential primary resonance mode even if knocking does not occur. Such vibration may appear in the vicinity of a frequency twice the resonance frequency. The vibration having a frequency twice the resonance frequency is included in the frequency band of the radial primary resonance mode.

  Therefore, in the present embodiment, the vibration of the frequency band A determined to correspond to the frequency band of the tangential secondary resonance mode, and the frequency band B determined to correspond to the tangential tertiary frequency band. The frequency band C vibration determined to correspond to the frequency band of vibration and tangential fourth-order resonance mode is extracted by a bandpass filter. Note that the frequency band of vibration to be extracted is not limited to three, and may be any number as long as it is one or more.

  As shown in FIG. 5, the frequency band A is a frequency band including the frequency F (A) ± X (X is a positive value). The frequency band B is a frequency band including the frequency F (B) ± X. The frequency band C is a frequency band including the frequency F (C) ± X. That is, the bandwidths of the frequency bands A to C are all 2 × X. The frequency bands A to C are determined by specifying the center frequencies F (A) to F (C).

  X is, for example, “1”. The frequencies F (A) to F (C) include the intake valve 116, the exhaust valve 118, the piston 108, and the injector 104 in addition to the vibration of the resonance frequency described above in the frequency bands A to C and the vibration of twice the resonance frequency. In addition, the vibration by the fuel pump 120 or the like, that is, the vibration by the noise component is not included. Thereby, the vibration peculiar to knocking can be extracted with high accuracy. A method for specifying the frequencies F (A) to F (C) will be described later. Further, the timing of opening and closing the intake valve 116 or the exhaust valve 118 is changed by, for example, a VVT (Variable Valve Timing) mechanism.

  By the way, if the bandwidth of the frequency band for extracting vibrations is narrow, vibrations caused by noise components other than those caused by knocking can be suppressed. However, characteristic parts of noise components (vibration occurrence timing and attenuation) Rate) is removed. In this case, even if the vibration is actually caused by a noise component, a vibration waveform not including the noise component, that is, a waveform similar to the vibration waveform at the time of knocking is detected. For this reason, it is difficult to distinguish vibrations caused by knocking and vibrations caused by noise from the vibration waveform.

  Therefore, in order to determine whether or not knocking has occurred in consideration of noise when noise is generated, as shown in FIG. 5, vibration in a wide frequency band D including frequency bands A to C is taken. Are extracted by a band pass filter. The vibration in the frequency band D is used to detect the vibration waveform of the engine 100.

  As shown in FIG. 5, the frequency band D is a frequency band including the frequency F (D) ± Y / 2 (Y is a positive value). That is, the bandwidth of the frequency band D is Y. The frequency band D is determined by specifying the bandwidth Y.

  For the frequency F (D), for example, the average value of the frequencies F (A) to F (C) is used so as to be the center of the frequencies F (A) to F (C). Bandwidth Y is specified such that frequency band D includes vibrations from intake valve 116, exhaust valve 118, piston 108, injector 104, fuel pump 120, and the like. A method for specifying the bandwidth Y will be described later.

  As shown in FIG. 6, in the frequency band D, the vibration waveform when knocking occurs has a shape in which the vibration gradually attenuates after the peak value of the vibration waveform, as indicated by the solid line. On the other hand, when knocking does not occur and vibrations are generated by the intake valve 116, the exhaust valve 118, the piston 108, the injector 104, the fuel pump 120, etc., the vibration waveform is quickly It becomes a shape to attenuate. Therefore, the vibration caused by knocking and the vibration caused by noise can be accurately distinguished from the vibration waveform of the frequency band F.

  The engine ECU 200 will be further described with reference to FIG. The engine ECU 200 includes an A / D (analog / digital) converter 400, a bandpass filter (1) 410, a bandpass filter (2) 420, a bandpass filter (3) 430, and a bandpass filter (4). 440 and an integration unit 450.

  The A / D converter 400 converts the analog signal transmitted from the knock sensor 300 into a digital signal. Bandpass filter (1) 410 passes only the signal of frequency band A among the signals transmitted from knock sensor 300. That is, only the vibration in the frequency band A is extracted from the vibration detected by knock sensor 300 by bandpass filter (1) 410.

  Bandpass filter (2) 420 passes only the signal of frequency band B among the signals transmitted from knock sensor 300. That is, only the vibration in the frequency band B is extracted from the vibration detected by the knock sensor 300 by the bandpass filter (2) 420.

  Bandpass filter (3) 430 passes only the signal in frequency band C among the signals transmitted from knock sensor 300. That is, only the vibration in the frequency band C is extracted from the vibration detected by the knock sensor 300 by the bandpass filter (3) 430.

  Bandpass filter (4) 440 passes only the signal of frequency band D among the signals transmitted from knock sensor 300. That is, only the vibration in the frequency band D is extracted from the vibration detected by knock sensor 300 by bandpass filter (4) 440.

  The integrating unit 450 integrates the signals selected by the bandpass filter (1) 410 to the bandpass filter (4) 440, that is, the vibration intensity by 5 degrees in terms of crank angle. Hereinafter, the integrated value is expressed as a 5-degree integrated value. The 5-degree integrated value is calculated for each frequency band.

  Among the calculated 5-degree integrated values, the 5-degree integrated values in the frequency bands A to C are added corresponding to the crank angle. That is, the vibration waveforms in the frequency bands A to C are synthesized. Further, a 5-degree integrated value of frequency band D is used as a vibration waveform of engine 100.

  The vibration waveform in frequency band D is compared with the knock waveform model shown in FIG. 8 to determine whether or not knocking has occurred. A knock waveform model is a model of a vibration waveform when knocking occurs in engine 100. The knock waveform model is stored in memory 202 of engine ECU 200.

  In the knock waveform model, the vibration intensity is expressed as a dimensionless number from 0 to 1, and the vibration intensity does not uniquely correspond to the crank angle. That is, in the knock waveform model of the present embodiment, it is determined that the vibration intensity decreases as the crank angle increases after the peak value of the vibration intensity. The corner is not fixed.

  The knock waveform model corresponds to vibrations after the peak value of the vibration intensity generated by knocking. Note that a knock waveform model corresponding to the vibration after the rise of vibration caused by knocking may be stored.

  The knock waveform model detects the vibration waveform of engine 100 when knocking is forcibly generated by experiments or the like, and is created and stored in advance based on the vibration waveform. Note that the method of creating the knock waveform model is not limited to this.

  In the comparison between the detected waveform and the knock waveform model, as shown in FIG. 9, the normalized waveform and the knock waveform model are compared. Here, normalization means, for example, dividing the 5-degree integrated value by the maximum value of the 5-degree integrated value in the detected vibration waveform to express the vibration intensity as a dimensionless number from 0 to 1. is there. The normalization method is not limited to this.

  Engine ECU 200 calculates a correlation coefficient K representing the degree to which the normalized vibration waveform is similar to the knock waveform model (representing the deviation between the vibration waveform and the knock waveform model). In the state where the timing when the vibration intensity is maximized in the vibration waveform after normalization and the timing when the vibration intensity is maximum in the knock waveform model are matched, the intensity in the vibration waveform after normalization and the intensity in the knock waveform model The correlation coefficient K is calculated by calculating the absolute value (deviation amount) of each difference for each crank angle (every 5 degrees). The absolute value of the difference between the intensity in the vibration waveform and the intensity in the knock waveform model may be calculated for each crank angle other than 5 degrees.

  The absolute value of the deviation between the normalized vibration waveform and knock waveform model for each crank angle is ΔS (I) (I is a natural number), and the value obtained by integrating the vibration intensity in the knock waveform model with the crank angle (knock waveform model) If S is the area, the correlation coefficient K is calculated by the equation K = (S−ΣΔS (I)) / S.

  Here, ΣΔS (I) is the sum of ΔS (I). In the present embodiment, correlation coefficient K is calculated as a larger value as the shape of the vibration waveform is closer to the shape of the knock waveform model. Therefore, when the vibration waveform includes a vibration waveform due to a factor other than knocking, the correlation coefficient K is calculated to be small. Note that the method of calculating the correlation coefficient K is not limited to this.

  Further, engine ECU 200 calculates knock magnitude N based on the largest 5-degree integrated value (peak value) among 5-degree integrated values in the combined waveforms of frequency bands A to C. If the maximum value of the integrated value of 5 degrees in the combined waveform of the frequency bands A to C is P, a value representing the vibration intensity of the engine 100 in a state where the engine 100 is not knocked is BGL (Back Ground Level). The knock magnitude N is calculated by the equation N = P / BGL. The BGL is determined in advance and stored in the memory 202, for example. Further, the calculation method of knock strength N is not limited to this.

  Engine ECU 200 determines that knocking has occurred when knock magnitude N is greater than determination value V (KX) and correlation coefficient K is greater than threshold value K (0). If it is determined that knocking has occurred, the ignition timing is retarded.

  With reference to FIG. 10, the process of specifying the frequencies F (A) to F (C) at the center of the frequency bands A to C and the bandwidth Y of the frequency band D will be described. In addition, the order of each process is not restricted to the order demonstrated below.

  In step (hereinafter, step is abbreviated as S) 100, vibration due to knocking occurs in the knock detection gate, and vibration due to intake valve 116, exhaust valve 118, piston 108, injector 104, fuel pump 120, etc. occurs. In a state where the engine 100 is operated as described above, the vibration intensity (S1) is detected for each vibration frequency by performing a fast Fourier transform (FET) on the signal transmitted from the knock sensor 300.

  In S102, the engine 100 is operated so that vibration due to knocking does not occur in the knock detection gate and vibrations due to the intake valve 116, the exhaust valve 118, the piston 108, the injector 104, the fuel pump 120, etc. occur. The vibration intensity (N1) is detected for each vibration frequency by performing a fast Fourier transform on the signal transmitted from the knock sensor 300.

  In S104, by dividing the vibration intensity (S1) by the vibration intensity (N1) for each frequency, the vibration intensity (S1) at the time of occurrence of knocking in a state including noise in the knock detection gate is obtained. An S / N ratio (1) representing a ratio with the vibration intensity (N1) when knocking does not occur is calculated.

  In S110, in a state where the engine 100 is operated so that vibration due to knocking occurs in the knock detection gate and vibrations due to the intake valve 116, the exhaust valve 118, the piston 108, the injector 104, the fuel pump 120, etc. do not occur. By performing a fast Fourier transform on the signal transmitted from knock sensor 300, vibration intensity (S2) is detected for each vibration frequency.

  In S112, in a state where engine 100 is operated so that vibration due to knocking does not occur in the knock detection gate and vibration due to intake valve 116, exhaust valve 118, piston 108, injector 104, fuel pump 120, etc. does not occur. The vibration intensity (N2) is detected for each vibration frequency by performing a fast Fourier transform on the signal transmitted from the knock sensor 300.

  In S114, by dividing the vibration intensity (S2) by the vibration intensity (N2) for each frequency, the vibration intensity at the time of knocking occurrence (S2) in a state in which no noise is included in the knock detection gate. And an S / N ratio (2) representing the ratio between the vibration intensity when knocking does not occur (N2).

  In S120, by dividing the SN ratio (1) in a state where noise is included in the knock detection gate by the SN ratio (2) in a state where noise is not included in the knock detection gate, the SN ratio (1) and The ratio with the SN ratio (2) is calculated.

  In S130, for each of a plurality of frequency bands including each frequency ± X of vibration, an integrated value obtained by integrating the SN ratio (1) in a state including noise in the knock detection gate is calculated. In other words, the center frequency of the frequency band having a bandwidth of 2 × X is changed (swept) from the minimum frequency to the maximum frequency of the obtained frequency, and for each frequency used as the center, An integral value of the SN ratio (1) of the frequency included in the 2 × X bandwidth is calculated. Instead of the SN ratio (1), the SN ratio (2) in a state where no noise is included in the knock detection gate may be used. In S132, the calculated integral value is plotted in correspondence with the center frequency of each frequency band.

  In S140, close to the theoretical in-cylinder pressure resonance frequency (for example, frequency of tangential second-order resonance mode, tangential third-order resonance mode, and tangential fourth-order resonance mode), SN ratio (1) and SN Based on the fact that the ratio to the ratio (2) is close to “1”, the SN ratio (1) is high, and the integral value is large, frequencies that meet these standards are set to the centers of the frequency bands A to C. Frequency F (A) to F (C).

  In S150, the vibration intensity (S1) obtained in a state including the vibration and noise caused by knocking in the knock detection gate is obtained as an average value (frequency F (D)) of frequencies F (A) to F (C). An integrated value obtained by integrating each frequency band having only a different bandwidth as the center is calculated. In other words, by changing the bandwidth of the frequency band centered on the average value of the frequencies F (A) to F (C), the integral value of the vibration intensity (S1) of the frequency included in each bandwidth is calculated. . Instead of the vibration intensity (S1), the vibration intensity (S2) obtained in a state where the knock detection gate includes vibration due to knocking and does not include noise may be used.

  In S152, each integral value is corrected by multiplying the value obtained by dividing the integral value of each frequency band by the bandwidth of each frequency band by a bandwidth (for example, 10 KHz) determined in advance as a reference. That is, the integrated value of each frequency band is corrected by the ratio of the bandwidth predetermined as the reference and the bandwidth of each frequency band (bandwidth predetermined as the reference / bandwidth of each frequency band).

  In S154, the corrected integral values are plotted for each bandwidth of each frequency band. In S156, with reference to the fact that the corrected integrated value is large, the bandwidth that matches this criterion is specified as the bandwidth Y of the frequency band D.

  A method for specifying the frequencies F (A) to F (C) at the center of the frequency bands A to C and the bandwidth Y of the frequency band D based on the flowchart as described above will be described.

  A state in which the engine 100 is operated (a state in which noise is generated) such that vibration due to knocking occurs in the knock detection gate and vibrations due to the intake valve 116, the exhaust valve 118, the piston 108, the injector 104, the fuel pump 120, etc. ), The vibration intensity (S1) indicated by the solid line in FIG. 11 is detected for each vibration frequency by performing a fast Fourier transform on the signal transmitted from knock sensor 300 (S100).

  Further, in the state where the engine 100 is operated so that vibration due to knocking does not occur in the knock detection gate and vibrations due to the intake valve 116, the exhaust valve 118, the piston 108, the injector 104, the fuel pump 120, etc. occur. By performing a fast Fourier transform on the signal transmitted from the sensor 300, the vibration intensity (N1) indicated by the broken line in FIG. 11 is detected for each vibration frequency (S102).

  By dividing the vibration intensity (S1) by the vibration intensity (N1), the S / N ratio (1) is calculated for each frequency, as indicated by the one-dot chain line in FIG. 11 (S104).

  As shown in FIG. 11, the intensity (N1) increases at the frequency at which noise appears. Therefore, the SN ratio (1) is small at the frequency at which noise vibration appears.

  Further, the engine 100 is operated so that vibration due to knocking occurs in the knock detection gate and vibrations due to the intake valve 116, the exhaust valve 118, the piston 108, the injector 104, the fuel pump 120, and the like are not generated (noise is generated). In a state where the vibration is not performed, the signal transmitted from the knock sensor 300 is fast Fourier transformed to detect the vibration intensity (S2) indicated by the solid line in FIG. 12 for each vibration frequency (S110).

  Further, knocking is not performed in the knock detection gate while the engine 100 is operated so that vibration due to knocking does not occur and vibration due to the intake valve 116, the exhaust valve 118, the piston 108, the injector 104, the fuel pump 120, and the like does not occur. By performing a fast Fourier transform on the signal transmitted from the sensor 300, the vibration intensity (N2) indicated by a broken line in FIG. 12 is detected for each vibration frequency (S112).

  By dividing the vibration intensity (S2) by the vibration intensity (N2) for each frequency, the SN ratio (2) indicated by the alternate long and short dash line in FIG. 12 is calculated (S114).

  By dividing the SN ratio (1) by the SN ratio (2), as shown in FIG. 13, the ratio between the SN ratio (1) and the SN ratio (2) is calculated (S120).

  Here, as described above, the SN ratio (1) becomes small at the frequency at which noise appears. Therefore, as shown in FIG. 13, the ratio between the SN ratio (1) and the SN ratio (2) becomes small at the frequency at which noise appears. On the other hand, at a frequency at which no noise appears, the ratio of the SN ratio (1) and the SN ratio (2) is close to “1”.

  Therefore, if the frequency is specified based on the fact that the ratio of the SN ratio (1) to the SN ratio (2) is close to “1”, the frequency at which the noise does not appear and the vibration due to the knocking is accurately specified. can do.

  By the way, as shown in FIG. 14, the SN ratio or the detected vibration intensity often has a high peak but a narrow bandwidth. In order to efficiently detect vibration due to knocking, it is desirable to select a frequency of vibration with a wide bandwidth.

  Therefore, as shown in FIG. 15, an integrated value is calculated by integrating the SN ratio (1) in the state including noise in the knock detection gate for each of a plurality of frequency bands including each frequency ± X (S130). That is, the center frequency of the frequency band having a bandwidth of 2 × X is changed (swept) from the minimum frequency to the maximum frequency, and the bandwidth of 2 × X is used for each frequency used as the center. An integral value of the SN ratio (1) of the frequency included in the is calculated. The calculated integral value is plotted in correspondence with the center frequency of each frequency band as shown in FIG. 16 (S132).

  It can be said that the frequency band with a large integrated value includes more vibration than the small frequency band. Therefore, based on the fact that the integral value is large, it is possible to select a vibration frequency with a wide bandwidth.

  Therefore, in addition to the basic criteria of being close to the theoretical in-cylinder pressure resonance frequency and having a high SN ratio (1), the ratio of the SN ratio (1) and the SN ratio (2) is close to “1”. On the basis of the fact that the integration value is large, the frequencies that meet these criteria are specified as the frequencies F (A) to F (C) at the centers of the frequency bands A to C (S140).

  As a result, the frequency at which the vibration due to knocking does not appear and the vibration due to knocking does not appear due to the intake valve 116, the exhaust valve 118, the piston 108, the injector 104, the fuel pump 120, etc. It can be specified as F (C). Therefore, when detecting vibration of engine 100, vibration due to knocking can be detected with high accuracy.

  On the other hand, in order to specify the bandwidth Y of the wide frequency band D, as shown in FIG. 17, the vibration intensity (S1) obtained in a state including the vibration due to knocking and the noise in the knock detection gate is expressed as An integrated value obtained by integrating each frequency band having only the bandwidth around the average value (frequency F (D)) of F (A) to F (C) is calculated (S150). That is, by changing the bandwidth of the frequency band centered on the average value of the frequencies F (A) to F (C), the integral value of the vibration intensity (S1) of the frequency included in each bandwidth is calculated. .

  In order to correct the difference in integral value due to the difference in bandwidth, the value obtained by dividing the integral value of each frequency band by the bandwidth of each frequency band is multiplied by a bandwidth (for example, 10 KHz) determined in advance as a reference, Each integral value is corrected (S152). Each corrected integrated value is plotted for each bandwidth of each frequency band as shown in FIG. 18 (S154).

  Since the vibration intensity (S1) is high at the frequency at which vibration due to knocking occurs, the frequency band of the bandwidth with a large corrected integrated value has a higher frequency at which vibration due to knocking occurs as shown in FIG. It can be said that many are included.

  Therefore, based on the fact that the corrected integrated value is large, a bandwidth that matches this criterion is specified as the bandwidth Y of the frequency band D (S156). Thereby, the bandwidth including vibration due to knocking can be specified.

  As described above, according to the method for specifying a frequency according to the present embodiment, vibration due to knocking occurs in the knock detection gate, and vibration due to an intake valve, an exhaust valve, a piston, an injector, a fuel pump, and the like occurs. In such a state that the engine is operated, the vibration intensity (S1) of the engine is detected for each vibration frequency. Further, in the state where the engine is operated so that vibration due to knocking does not occur in the knock detection gate and vibration due to the intake valve, the exhaust valve, the piston, the injector, the fuel pump, etc., is generated, the vibration intensity (N1 ) Is detected for each frequency of vibration. By dividing the vibration intensity (S1) by the vibration intensity (N1), the SN ratio (1) is calculated for each frequency. Further, the strength of the engine vibration (S2) in a state where the engine is operated such that vibration due to knocking occurs in the knock detection gate and vibration due to the intake valve, exhaust valve, piston, injector, fuel pump, etc. does not occur. Is detected for each frequency of vibration. Further, in the state where the engine is operated so that vibration due to knocking does not occur in the knock detection gate and vibration due to the intake valve, exhaust valve, piston, injector, fuel pump, etc. does not occur, the vibration intensity (N2 ) Is detected for each frequency of vibration. For each frequency, the SN ratio (2) is calculated by dividing the vibration intensity (S2) by the vibration intensity (N2). By dividing the SN ratio (1) by the SN ratio (2), the ratio of the SN ratio (1) and the SN ratio (2) is calculated. The frequency that matches the standard including that the ratio of the SN ratio (1) and the SN ratio (2) is close to “1” is the center of the frequency band A to C of the vibration extracted to determine the presence or absence of knocking. It is specified as frequencies F (A) to F (C). As a result, the frequencies F (A) to F (C) at the centers of the frequency bands A to C are defined as frequencies at which vibrations due to intake valves, exhaust valves, pistons, injectors, fuel pumps, etc. do not appear and vibrations due to knocking appear. Can be identified.

<Second Embodiment>
Hereinafter, a second embodiment of the present invention will be described. In the present embodiment, when the center frequencies F (A) to F (C) of the frequency bands A to C are specified, an integrated value obtained by integrating the vibration intensity instead of the SN ratio is calculated. This is different from the first embodiment. Other structures are the same as those in the first embodiment. Therefore, detailed description thereof will not be repeated here.

  Referring to FIG. 19, the process of specifying the center frequencies F (A) to F (C) of the frequency bands A to C and the bandwidth Y of the frequency band D in the present embodiment will be described. In addition, the order of each process is not restricted to the order demonstrated below. The same steps as those in the first embodiment are given the same step numbers. Therefore, the details thereof will not be repeated here.

  In S230, an integral value obtained by integrating the vibration intensity (S1) for each of a plurality of frequency bands including the vibration frequencies ± X is calculated. In other words, the frequency at the center of the frequency band having a bandwidth of 2 × X is changed (swept) from the minimum frequency to the maximum frequency, and for each frequency used as the center, the bandwidth of 2 × X An integral value of the intensity (S1) of the frequency included in the width is calculated. The vibration intensity (S2) may be used instead of the vibration intensity (S1).

  A method for specifying the frequencies F (A) to F (C) at the center of the frequency bands A to C and the bandwidth Y of the frequency band D based on the flowchart as described above will be described. Since steps other than S230 are the same as those in the first embodiment, detailed description thereof will not be repeated here.

  As shown in FIG. 20, an integrated value is calculated by integrating the vibration intensity (S1) in a state including noise in the knock detection gate for each of a plurality of frequency bands including each frequency ± X (S230). That is, the center frequency of the frequency band having a bandwidth of 2 × X is changed (swept) from the minimum frequency to the maximum frequency, and the bandwidth of 2 × X is used for each frequency used as the center. The integral value of the intensity (S1) of the frequency included in is calculated. Even if it does in this way, there can exist an effect similar to the above-mentioned 1st Embodiment.

<Third Embodiment>
Hereinafter, a third embodiment of the present invention will be described. In the present embodiment, when specifying the center frequencies F (A) to F (C) of the frequency bands A to C, the ratio between the SN ratio (1) and the SN ratio (2) is used instead of the SN ratio. This is different from the first embodiment described above in that an integrated value is calculated. Other structures are the same as those in the first embodiment. Therefore, detailed description thereof will not be repeated here.

  With reference to FIG. 21, the process of identifying the frequencies F (A) to F (C) at the center of the frequency bands A to C and the bandwidth Y of the frequency band D in the present embodiment will be described. In addition, the order of each process is not restricted to the order demonstrated below. The same steps as those in the first embodiment are given the same step numbers. Therefore, the details thereof will not be repeated here.

  In S330, an integral value obtained by integrating the ratio of the SN ratio (1) and the SN ratio (2) is calculated for each of a plurality of frequency bands including each frequency ± X of vibration. In other words, the frequency at the center of the frequency band having a bandwidth of 2 × X is changed (swept) from the minimum frequency to the maximum frequency, and for each frequency used as the center, the bandwidth of 2 × X An integral value of the ratio between the SN ratio (1) and the SN ratio (2) at the frequency included in the width is calculated.

  A method for specifying the frequencies F (A) to F (C) at the center of the frequency bands A to C and the bandwidth Y of the frequency band D based on the flowchart as described above will be described. Since steps other than S330 are the same as those in the first embodiment, detailed description thereof will not be repeated here.

  As shown in FIG. 22, an integral value is calculated by integrating the ratio of the SN ratio (1) and the SN ratio (2) for each of a plurality of frequency bands including each frequency ± X (S330). That is, the center frequency of the frequency band having a bandwidth of 2 × X is changed (swept) from the minimum frequency to the maximum frequency, and the bandwidth of 2 × X is used for each frequency used as the center. An integrated value of the ratio of the SN ratio (1) and the SN ratio (2) at the frequency included in the.

  As described above, the ratio between the SN ratio (1) and the SN ratio (2) is small at the frequency at which vibrations from the intake valve 116, the exhaust valve 118, the piston 108, the injector 104, the fuel pump 120, and the like appear. Therefore, as shown in FIG. 23, it can be said that vibrations due to the intake valve 116, the exhaust valve 118, the piston 108, the injector 104, the fuel pump 120, and the like appear at a frequency with a small integral value.

  Therefore, based on the fact that the integral value is large, it is possible to specify a frequency at which vibrations by the intake valve 116, the exhaust valve 118, the piston 108, the injector 104, the fuel pump 120, etc. do not appear.

<Fourth embodiment>
Hereinafter, a fourth embodiment of the present invention will be described. The present embodiment is different from the first embodiment described above in that, when the bandwidth Y of the frequency body D is specified, the integrated value of the SN ratio is calculated instead of the vibration intensity. Other structures are the same as those in the first embodiment. Therefore, detailed description thereof will not be repeated here.

  With reference to FIG. 24, the process of specifying the frequencies F (A) to F (C) at the center of the frequency bands A to C and the bandwidth Y of the frequency band D in the present embodiment will be described. In addition, the order of each process is not restricted to the order demonstrated below. The same steps as those in the first embodiment are given the same step numbers. Therefore, the details thereof will not be repeated here.

  In S450, an integrated value obtained by integrating the SN ratio (1) for each frequency band with only the bandwidth differing from the average value (frequency F (D)) of the frequencies F (A) to F (C) is calculated. . In other words, the integrated value of the SN ratio (1) of the frequency included in each bandwidth is calculated by changing the bandwidth of the frequency band centered on the average value of the frequencies F (A) to F (C). Note that the SN ratio (2) may be used instead of the SN ratio (1).

  A method for specifying the frequencies F (A) to F (C) at the center of the frequency bands A to C and the bandwidth Y of the frequency band D based on the flowchart as described above will be described. Since steps other than S450 are the same as those in the first embodiment, detailed description thereof will not be repeated here.

  As shown in FIG. 25, the integrated value obtained by integrating the SN ratio (1) for each frequency band having only the bandwidth around the average value (frequency F (D)) of the frequencies F (A) to F (C). Is calculated (S450).

  Even in this case, since the SN ratio (1) becomes large at the frequency at which the vibration due to knocking appears, the same effect as in the first embodiment described above can be obtained.

<Fifth embodiment>
The fifth embodiment of the present invention will be described below. In the present embodiment, when the bandwidth Y of the frequency body D is specified, an integrated value obtained by integrating the ratio of the SN ratio (1) and the SN ratio (2) is calculated instead of the vibration intensity (S1). This is different from the first embodiment described above. Other structures are the same as those in the first embodiment. Therefore, detailed description thereof will not be repeated here.

  With reference to FIG. 26, the process of specifying the frequencies F (A) to F (C) at the center of the frequency bands A to C and the bandwidth Y of the frequency band D in the present embodiment will be described. In addition, the order of each process is not restricted to the order demonstrated below. The same steps as those in the first embodiment are given the same step numbers. Therefore, the details thereof will not be repeated here.

  In S550, the ratio of the SN ratio (1) and the SN ratio (2) is changed to a frequency band in which only the bandwidth is different from the average value (frequency F (D)) of the frequencies F (A) to F (C). The integrated value integrated every time is calculated. In other words, by changing the bandwidth of the frequency band centered on the average value of the frequencies F (A) to F (C), the SN ratio (1) and the SN ratio (2) at the frequency included in each bandwidth The integral value obtained by integrating the ratio is calculated.

  A method for specifying the frequencies F (A) to F (C) at the center of the frequency bands A to C and the bandwidth Y of the frequency band D based on the flowchart as described above will be described. Since steps other than S550 are the same as those in the first embodiment, detailed description thereof will not be repeated here.

  As shown in FIG. 27, the ratio of the SN ratio (1) and the SN ratio (2) is determined by using only the bandwidth around the average value (frequency F (D)) of the frequencies F (A) to F (C). An integrated value obtained by integrating for each different frequency band is calculated (S550).

  Even in this case, since the ratio of the SN ratio (1) and the SN ratio (2) becomes large at the frequency at which the vibration due to knocking appears as described above, the same effect as that of the first embodiment is obtained. Can play.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic block diagram which shows the engine of a vehicle. It is a figure (the 1) which shows the frequency band of the vibration of a cylinder pressure. It is a figure which shows the frequency band of the vibration at the time of generation | occurrence | production of knocking. It is a figure which shows the frequency band of the vibration when knocking does not occur. It is a figure which shows frequency band AD. 6 is a diagram illustrating a vibration waveform in a frequency band D. It is a control block diagram which shows engine ECU of FIG. It is a figure which shows the knock waveform model memorize | stored in memory of engine ECU. It is the figure which compared the vibration waveform after normalization, and a knock waveform model. The flowchart which shows the process of specifying the frequency F (A) -F (C) of the center of frequency band AC, and the bandwidth Y of the frequency band D in the frequency identification method which concerns on the 1st Embodiment of this invention. It is. It is a figure (the 1) which shows the intensity | strength and SN ratio of a vibration. It is a figure (the 2) which shows the intensity | strength and SN ratio of a vibration. It is a figure (the 1) which shows the ratio of SN ratio (1) and SN ratio (2). It is a figure which shows the intensity | strength of a vibration. It is a figure (the 1) which shows SN ratio. It is a figure which shows the integrated value of SN ratio. It is a figure (the 1) which shows the intensity | strength of a vibration. It is a figure which shows the integrated value of intensity | strength. The flowchart which shows the process of specifying the frequency F (A) -F (C) of the center of frequency band AC, and the bandwidth Y of the frequency band D in the frequency identification method which concerns on the 2nd Embodiment of this invention. It is. It is a figure (the 2) which shows the intensity | strength of a vibration. The flowchart which shows the process of specifying the frequency F (A) -F (C) of the center of frequency band AC, and the bandwidth Y of the frequency band D in the frequency identification method which concerns on the 3rd Embodiment of this invention. It is. It is a figure (the 2) which shows the ratio of SN ratio (1) and SN ratio (2). It is a figure which shows the integral value of the ratio of SN ratio (1) and SN ratio (2). The flowchart which shows the process of specifying the frequency F (A) -F (C) of the center of frequency band AC, and the bandwidth Y of the frequency band D in the frequency identification method which concerns on the 4th Embodiment of this invention. It is. It is a figure (the 2) which shows SN ratio. The flowchart which shows the process of specifying the frequency F (A) -F (C) of the center of frequency band AC, and the bandwidth Y of the frequency band D in the frequency identification method which concerns on the 4th Embodiment of this invention. It is. It is a figure (the 3) which shows the ratio of SN ratio (1) and SN ratio (2).

Explanation of symbols

  100 engine, 102 air cleaner, 104 injector, 106 spark plug, 108 piston, 110 crankshaft, 112 three-way catalyst, 114 throttle valve, 116 intake valve, 118 exhaust valve, 120 fuel pump, 200 engine ECU, 202 memory, 300 knock Sensor, 302 Water temperature sensor, 304 Timing rotor, 306 Crank position sensor, 308 Throttle opening sensor, 310 Vehicle speed sensor, 312 Ignition switch, 400 A / D converter, 410 Band pass filter (1), 420 Band pass filter (2 ) 430 band pass filter (3), 440 band pass filter (4), 450 accumulator.

Claims (7)

A method for identifying the frequency of vibrations extracted to determine the presence or absence of knocking,
In a state where vibration due to knocking occurs at a predetermined crank angle interval and vibration due to operation of a predetermined component provided in the internal combustion engine occurs, the first intensity of vibration of the internal combustion engine is Detecting at predetermined crank angle intervals;
In a state where vibration due to knocking does not occur at the predetermined crank angle interval and vibration due to operation of the predetermined component occurs, a second intensity of vibration of the internal combustion engine is determined in advance. Detecting at a crank angle interval;
Calculating a first ratio of the first intensity and the second intensity for each frequency of vibration;
The third strength of the internal combustion engine is set to the predetermined crank angle in a state where vibration due to knocking occurs at the predetermined crank angle interval and vibration due to operation of the predetermined component does not occur. Detecting at intervals of
The fourth strength of the internal combustion engine is set to the predetermined crank in a state in which vibration due to knocking does not occur at the predetermined crank angle interval and vibration due to operation of the predetermined component does not occur. Detecting at angular intervals;
Calculating a second ratio of the third intensity and the fourth intensity for each frequency of vibration;
A method of specifying a frequency, comprising: a step of specifying a frequency of vibration to be extracted based on a result of comparing the first ratio and the second ratio for each frequency and the first ratio. The specifying method further includes a step of calculating an integral value obtained by integrating one of the first ratio and the second ratio for each of a plurality of frequency bands having the same width,
The step of identifying the frequency of vibration generated by knocking is extracted based on the result of comparing the first ratio and the second ratio for each frequency and the first ratio, and the integrated value. The frequency specifying method according to claim 1, further comprising: specifying a frequency of vibration to be performed. The specifying method further includes a step of calculating an integral value obtained by integrating any one of the first intensity and the third intensity for each of a plurality of frequency bands having the same width,
The step of identifying the frequency of vibration generated by knocking is extracted based on the result of comparing the first ratio and the second ratio for each frequency and the first ratio, and the integrated value. The frequency specifying method according to claim 1, further comprising: specifying a frequency of vibration to be performed. The identification method is as follows:
Calculating an integrated value obtained by integrating the ratio of the first ratio and the second ratio for each of a plurality of frequency bands having the same width;
The step of identifying the frequency of vibration generated by knocking is extracted based on the result of comparing the first ratio and the second ratio for each frequency and the first ratio, and the integrated value. The frequency specifying method according to claim 1, further comprising: specifying a frequency of vibration to be performed. In the specifying method, a first integrated value obtained by integrating one of the first ratio and the second ratio for each of a plurality of frequency bands having different widths, which is determined based on the same frequency. A calculating step;
Calculating a second integral value obtained by correcting each of the first integral values based on a width of each frequency band and a ratio of a predetermined width;
The frequency specifying method according to claim 1, further comprising: specifying a width of a frequency band of vibration to be extracted based on each of the second integrated values. In the specifying method, a first integrated value obtained by integrating one of the first intensity and the second intensity for each of a plurality of frequency bands having different widths, which is determined based on the same frequency. A calculating step;
Calculating a second integral value obtained by correcting each of the first integral values based on a width of each frequency band and a ratio of a predetermined width;
The frequency specifying method according to claim 1, further comprising: specifying a width of a frequency band of vibration to be extracted based on each of the second integrated values. The identification method is as follows:
Calculating a first integral value obtained by integrating the ratio of the first ratio and the second ratio for each of a plurality of frequency bands having the same width, which is determined based on the same frequency;
Calculating a second integral value obtained by correcting each of the first integral values based on a width of each frequency band and a ratio of a predetermined width;
The frequency specifying method according to claim 1, further comprising: specifying a width of a frequency band of vibration to be extracted based on each of the second integrated values.

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