JP4410719B2 - Internal combustion engine knock determination device - Google Patents

Description

  The present invention relates to a knock determination device, and more particularly to a knock determination device for an internal combustion engine that determines whether or not knocking has occurred based on a vibration waveform of the internal combustion engine.

  Conventionally, a technique for detecting knocking of an internal combustion engine is known. Japanese Patent Laying-Open No. 2001-227400 (Patent Document 1) discloses a knock control device for an internal combustion engine that can accurately determine whether or not knocking has occurred. A knock control device for an internal combustion engine described in Patent Literature 1 includes a signal detection unit that detects a vibration waveform signal generated in the internal combustion engine, and a period in which the vibration waveform signal detected by the signal detection unit is equal to or greater than a predetermined value. Is detected as an occurrence period, a peak position detection unit that detects a peak position in the occurrence period detected by the occurrence period detection unit, and occurrence of knock in the internal combustion engine based on the relationship between the occurrence period and the peak position A knock determination unit that determines presence or absence, and a knock control unit that controls the operating state of the internal combustion engine in accordance with a determination result by the knock determination unit. The knock determination unit determines that knock (knocking) has occurred when the peak position for the generation period is within a predetermined range.

According to the knock control device for an internal combustion engine described in this publication, the vibration waveform signal generated in the internal combustion engine is detected by the signal detection unit, and the generation period and the peak position where the vibration waveform signal is equal to or greater than a predetermined value. Are detected by the occurrence period detector and the peak position detector, respectively. In this way, by knowing at which position in the generation period of the vibration waveform signal the peak is generated, the knock determination unit determines whether or not knocking has occurred in the internal combustion engine, and the internal combustion engine is determined according to the knock determination result. The operating state is controlled. In the knock determination unit, when the peak position with respect to the occurrence period is within a predetermined range, that is, with a waveform shape such that the peak position appears earlier with respect to the occurrence period of the predetermined length of the vibration waveform signal. In some cases, it is recognized as unique when a knock occurs. As a result, even when the operating state of the internal combustion engine changes abruptly or when the electric load is turned on / off, the presence or absence of knocking in the internal combustion engine is accurately determined, and the operating state of the internal combustion engine can be controlled appropriately. .
JP 2001-227400 A

  However, even when knocking occurs, vibration having a magnitude greater than that caused by knocking may be detected as noise. That is, there is a case where the magnitude of vibration caused by knock sensor abnormality or the vibration of the internal combustion engine itself is greater than the magnitude of vibration caused by knocking. In such a case, in the knock control device for an internal combustion engine described in Japanese Patent Application Laid-Open No. 2001-227400, since knocking occurs, the peak position with respect to the generation period is outside the predetermined range. There has been a problem that it may be erroneously determined that knocking has not occurred.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a knock determination device for an internal combustion engine that can accurately determine whether knock has occurred or not. .

  A knocking determination device according to a first aspect of the present invention determines knocking of an internal combustion engine. The knock determination device includes a crank angle detection unit for detecting a crank angle of the internal combustion engine, a waveform detection unit for detecting a vibration waveform of the internal combustion engine between the predetermined crank angles, Storage means for storing in advance the vibration waveform of the internal combustion engine between the crank angles, and whether the detected waveform is a waveform in which the vibration intensity continuously decreases starting from the angle corresponding to the peak of the waveform Based on whether or not, a noise determination means for determining whether or not vibration corresponding to noise is superimposed on the detected waveform, and determination that vibration corresponding to noise is not superimposed on the detected waveform Then, the knocking determination means for determining whether knocking has occurred in the internal combustion engine based on the result of comparing the detected waveform with the waveform stored in the storage means Including the.

  According to the first invention, the crank angle detecting means detects the crank angle of the internal combustion engine, and the waveform detecting means detects the waveform of the vibration of the internal combustion engine between the predetermined crank angles. The storage means stores a vibration waveform of the internal combustion engine during a predetermined crank angle, and the detected waveform is not a waveform in which the vibration intensity continuously decreases starting from an angle corresponding to the peak of the waveform. Then, it is determined that the vibration corresponding to the noise is superimposed on the detected waveform. If it is not determined that the vibration corresponding to the noise is superimposed on the detected waveform, whether or not knocking has occurred in the internal combustion engine based on the result of comparing the detected waveform with the waveform stored in the storage means Determine whether. In this way, for example, whether a knock waveform model that is a vibration waveform when knocking has occurred is created in advance by comparing the knock waveform model with the detected waveform, for example, whether knocking has occurred. It can be determined whether or not. In particular, if the detected waveform is not a waveform in which the vibration intensity continuously decreases starting from an angle corresponding to the peak of the waveform, that is, a waveform having a plurality of portions corresponding to the peak. It can be determined that the vibration corresponding to the noise is superimposed on. Therefore, if it is determined that the vibration corresponding to the noise is not superimposed, the detected waveform and the knock waveform model are compared to suppress the deterioration of the correlation coefficient due to the noise, and to the internal combustion engine. It can be determined whether or not knocking has occurred. Therefore, it is possible to provide a knock determination device that can accurately determine whether knock has occurred in the internal combustion engine.

  In the knock determination device according to the second invention, in addition to the configuration of the first invention, the waveform stored in the storage means is a waveform in which the vibration intensity continuously decreases starting from an angle corresponding to the peak of the waveform. It is. The noise determination means includes means for determining that vibration corresponding to noise is superimposed on the detected waveform when the detected waveform and the waveform stored in the storage means have a portion that intersects.

  According to the second invention, when the noise determining means has a portion where the detected waveform and the waveform stored in the storage means intersect, it is determined that the vibration corresponding to the noise is superimposed on the detected waveform. To do. The stored waveform represents vibration corresponding to knocking, and is a waveform in which the vibration intensity continuously decreases starting from an angle corresponding to the peak of the waveform. So, for example, if the detected waveform matches the peak of the stored waveform and the detected waveform has a section that exceeds the stored waveform after it falls below, the detected waveform corresponds to the peak. It can be determined that the waveform has a plurality of portions. That is, it can be determined that vibration corresponding to noise is superimposed on the detected waveform.

  In the knocking determination device according to the third aspect of the invention, in addition to the configuration of the first aspect of the invention, the noise determination means has a continuous angle corresponding to the vibration intensity extracted in descending order from the largest vibration intensity of the detected waveform. Otherwise, a means for determining that vibration corresponding to noise is superimposed is included.

  According to the third invention, when the angle corresponding to the vibration intensity extracted in descending order from the largest vibration intensity of the detected waveform is not continuous, the waveform in which the vibration intensity continuously decreases starting from the angle corresponding to the peak Therefore, it can be determined that the vibration corresponding to the noise is superimposed on the detected waveform.

  In addition to the configuration of any one of the first to third aspects, the knocking determination device according to the fourth aspect of the present invention is configured such that when it is determined that the vibration corresponding to the noise is superimposed on the detected waveform, the peak of the waveform Further included is a correcting means for correcting the vibration intensity to have a waveform that continuously decreases starting from the angle corresponding to. The knocking determination means includes means for determining whether or not knocking has occurred in the internal combustion engine based on a result of comparing the corrected waveform and the waveform stored in the storage means.

  According to the fourth aspect of the invention, when it is determined that the vibration corresponding to the noise is superimposed on the detected waveform, the vibration intensity continuously decreases from the angle corresponding to the peak of the waveform. To correct. The knocking determination means determines whether knocking of the internal combustion engine has occurred based on the result of comparing the corrected waveform and the waveform stored in the storage means. When vibration corresponding to noise is superimposed on the detected waveform, even if a waveform including vibration corresponding to knocking is detected when comparing the detected waveform and the waveform stored in the storage means, The correlation coefficient with the stored waveform deteriorates. For this reason, the accuracy of knocking determination may deteriorate. Therefore, when it is determined that vibration corresponding to noise is superimposed, it is possible to cope with knocking by correcting the waveform so that the vibration intensity continuously decreases starting from the angle corresponding to the peak of the waveform. In the case where a waveform including vibration to be detected is detected, the deterioration of the correlation coefficient with the stored waveform can be suppressed. Therefore, it can be accurately determined whether or not knocking has occurred in the internal combustion engine.

  In the knock determination device according to the fifth aspect of the invention, in addition to the configuration of the fourth aspect of the invention, the correcting means includes vibrations at a reference angle that is a reference in the detected waveform and at each of a plurality of angles different from the reference angle. Means for correcting the detected waveform by the average value of the rate of change of the plurality of waveforms formed based on the intensity is included.

  According to the fifth invention, the correction means is an average of the change rates of the plurality of waveforms formed based on the vibration intensity at the reference angle serving as a reference in the detected waveform and each of the plurality of angles different from the reference angle. The detected waveform is corrected by the value. As a result, even when noise vibration is superimposed on the detected waveform, the detected waveform can be corrected to a waveform in which the vibration intensity continuously decreases starting from the angle corresponding to the peak. Thus, it is possible to suppress the occurrence of a large deviation between the waveform stored in the storage means and the corrected waveform due to the vibration of the superimposed noise. Therefore, even if vibration corresponding to knocking including noise occurs, it is possible to suppress the deterioration of the correlation coefficient between the corrected waveform and the stored waveform. Therefore, it can be accurately determined whether knocking has occurred in the internal combustion engine.

  In the knock determination device according to the sixth aspect of the present invention, in addition to the configuration of the fifth aspect, the reference angle is an angle corresponding to the peak of the vibration intensity in the detected waveform. The correction means includes a rate of change of a waveform formed based on the vibration intensity at the reference angle and the vibration intensity at the first angle different from the reference angle, and the vibration intensity at the reference angle and the second different from the reference angle. Means for correcting the detected waveform with an average value of the rate of change of the waveform formed based on the vibration intensity at the angle is included. The first angle and the second angle are different. The first angle and the second angle are larger than the reference angle.

  According to the sixth invention, the rate of change of the waveform formed based on the vibration intensity at the reference angle corresponding to the peak of the vibration intensity and the vibration intensity at the first angle, and the vibration intensity at the reference angle and the second The detected waveform is corrected by the average value of the rate of change of the waveform formed based on the vibration intensity at the angle. By correcting the detected waveform based on the average value of the change rate of the waveform after the reference angle, the detected waveform corresponds to the peak even when the vibration of noise is superimposed on the detected waveform. Since it can be corrected to a waveform in which the vibration intensity continuously decreases starting from the angle, a large deviation occurs between the waveform stored in the storage means and the corrected waveform due to the vibration of the superimposed noise. Can be suppressed. Therefore, even if vibration corresponding to knocking including noise occurs, it is possible to suppress the deterioration of the correlation coefficient between the corrected waveform and the stored waveform. Therefore, it can be accurately determined whether knocking has occurred in the internal combustion engine.

  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>
With reference to FIG. 1, a vehicle engine 100 equipped with a knock determination device according to an embodiment of the present invention will be described. The knocking determination device according to the present embodiment is realized by a program executed by an engine ECU (Electronic Control Unit) 200, for example.

  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.

  Engine 100 is controlled by engine ECU 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 clamp position sensor 306 increases or 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. .

  In the present embodiment, engine ECU 200 determines a predetermined knock detection gate (a predetermined second crank angle from a predetermined first crank angle based on a signal and a crank angle transmitted from knock sensor 300). The vibration waveform of the engine 100 (hereinafter referred to as a vibration waveform) is detected in the period up to this point), and whether or not knocking has occurred in the engine 100 is determined based on the detected vibration waveform. 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, vibration of a frequency near the frequency indicated by the solid line in FIG. That is, when knocking occurs, vibrations of frequencies included in first frequency band A, second frequency band B, third frequency band C, and fourth frequency band D are generated in engine 100. Note that CA in FIG. 2 indicates a crank angle. Moreover, the frequency band including the frequency of the vibration resulting from knocking is not limited to four.

  Among these frequency bands, the fourth frequency band D includes the resonance frequency of the engine 100 itself, which is indicated by a one-dot chain line in FIG. Resonance frequency vibration occurs regardless of knocking.

  Therefore, in the present embodiment, the vibration waveform is detected based on the intensity (magnitude) of vibration in the first frequency band A to the third frequency band C that does not include the resonance frequency. The number of frequency bands used for detecting the vibration waveform is not limited to three. The detected vibration waveform is compared with a knock waveform model described later.

  In order to determine whether or not knocking has occurred, the memory 202 of the engine ECU 200 stores a knock waveform model that is a model of a vibration waveform when knocking has occurred in the engine 100 as shown in FIG. .

  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. In the present embodiment, for example, the knock waveform model is stored in the memory 202 with the crank angle at which the vibration intensity has a peak value as zero. At this time, for example, a knock waveform model up to a predetermined angle β (1) is stored in the memory 202. The predetermined angle β (1) is an angle corresponding to an angle from the angle corresponding to the peak of the detected waveform to the end of the section of the knock detection gate when compared with the waveform detected by the knock sensor 300. If it is, it will not specifically limit. The knock waveform model is a composite wave of vibrations in the first frequency band A to the third frequency band C.

  The knock waveform model in the present embodiment 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.

  Engine ECU 200 compares the detected waveform with the stored knock waveform model, and determines whether knock has occurred in engine 100 or not.

  In the present invention, engine ECU 200 responds to noise in the detected waveform if the vibration waveform detected by knock sensor 300 is not a waveform in which the vibration intensity continuously decreases starting from an angle corresponding to the peak of the vibration waveform. It is characterized in that it is determined that the vibration to be superimposed is superimposed. Further, in the present invention, when it is determined that vibration corresponding to noise is superimposed on the detected waveform, engine ECU 200 has a waveform in which the vibration intensity continuously decreases starting from the angle corresponding to the peak. As described above, the feature is that the detected waveform is corrected.

  As shown in FIG. 4, when comparing the detected vibration waveform (solid line) and the knock waveform model (thin line), if vibrations other than knocking are superimposed, the vibration waveform at the crank angle α (3) is Since there is a deviation from the knock waveform model, the correlation coefficient between the detected vibration waveform and the knock waveform model may deteriorate. The vibration other than knocking is, for example, vibration caused by seating noise of the intake valve 116 or the exhaust valve 118 or the operation of the injector 104.

  For example, as shown in FIGS. 5 (A), 5 (B), and 5 (C), the vibration intensity change (solid line) after the angle α (1) corresponding to the detected waveform peak is detected. The knock waveform model (thin line) matched with the angle corresponding to the peak of the waveform is compared.

  In the waveform (solid line) shown in FIG. 5A, the vibration intensity after the angle α (1) corresponding to the peak of the detected waveform is continuously lower than the knock waveform model (thin line). In the waveform (solid line) shown in FIG. 5B, the vibration intensity after the angle α (1) corresponding to the peak of the detected waveform continuously exceeds the knock waveform model (thin line). On the other hand, in the waveform (solid line) shown in FIG. 5C, the vibration intensity after the angle α (1) corresponding to the peak of the detected waveform is a knock waveform model (thin line) at the angle α (2). Below the knock waveform model at angle α (3).

  Although the three waveforms as described above have different shapes, there is almost no difference in the correlation coefficient for the knock waveform model. This is because the correlation coefficient does not express the difference in shape in detail. The knock waveform model represents vibration corresponding to knocking, and has a waveform in which the vibration intensity continuously decreases. Therefore, in the waveform as shown in FIG. 5C, when the angle α (2) is below the knock waveform model and then exceeds the angle α (3), the vibration corresponding to the noise is superimposed on the detected waveform. It is thought that. Therefore, as shown in FIG. 5C, when noise is superimposed on the detected waveform, whether or not knocking has occurred based on the correlation coefficient between the detected waveform and the knock waveform model. If it is determined, the accuracy may deteriorate.

  Therefore, as shown in FIG. 5C, when the detected waveform matches the angle corresponding to the peak of the knock waveform model, the engine ECU 200 matches the angle α (corresponding to the peak of the detected waveform). 1) After that, it is determined whether or not there is a portion where the detected waveform and the knock waveform model intersect. That is, in this embodiment, engine ECU 200 determines whether or not there is a section in which the vibration intensity of the detected waveform exceeds after the vibration intensity of the knock waveform model falls below. When engine ECU 200 has the above-described section in the detected waveform, engine ECU 200 determines that noise is superimposed.

  When engine ECU 200 determines that the vibration corresponding to the noise is superimposed on the detected waveform, in the vibration waveform detected by knock sensor 300, the reference between the top dead center and the crank angle from 90 degrees. The detected waveform is corrected and corrected based on the average value of the change rates of the plurality of waveforms formed based on the vibration angles at the reference angle and each of a plurality of angles different from the reference angle. Whether or not knocking has occurred in engine 100 is determined based on the result of comparing the vibration waveform and the knock waveform model. The reference angle is an angle corresponding to the peak of the detected vibration waveform in the present embodiment, but is not particularly limited.

  In the present embodiment, in the vibration waveform detected by knock sensor 300, vibration intensity A (1) corresponding to the peak of the vibration waveform at angle α (1) and angle α (2) different from angle α (1). The rate of change of the vibration waveform formed based on the vibration intensity A (2) at the angle, the vibration intensity A (1) at the angle α (1), and the angle α different from the angle α (1) and the angle α (2). The detected vibration waveform is corrected by an average value of the change rate of the vibration waveform formed based on the vibration intensity A (3) in (3). In the present embodiment, the rate of change is also referred to as a rate of attenuation because it particularly refers to the rate of change at the time of attenuation after the peak of vibration intensity.

  In the present embodiment, both the angle α (2) and the angle α (3) are larger than the angle α (1). For example, the angle α (2) is an angle advanced 10 degrees from the angle α (1) corresponding to the peak of the detected vibration waveform, and α (3) is an angle advanced 5 degrees from the angle α (1). Suppose that

  Furthermore, the average value of the change rates is not limited to the average value of the change rates corresponding to the two angles of the angle α (2) and the angle (3). For example, the detected vibration waveform may be corrected based on the average value of the change rate of the vibration waveform formed at the angle α (1) and each of the three or more angles.

  In the present embodiment, an expression representing an attenuation waveform after the peak of the vibration intensity is represented by an exponential function expression to be described later, but is not particularly limited thereto.

  As shown in FIG. 6, a line having an attenuation factor λ (1) is formed by the vibration intensity A (1) at the angle α (1) and the vibration intensity A (2) at the angle α (2). On the other hand, a line having an attenuation factor λ (2) is formed by the vibration intensity A (1) at the angle α (1) and the vibration intensity A (3) at the angle α (3). Then, the average value λ (3) of the attenuation rate in each line is calculated from the equation (average value λ (3)) = (λ (1) + λ (2)) / 2. The waveform after the angle α (1) corresponding to the peak is corrected using the calculated average value λ (3).

  On the other hand, for the knock waveform model, when the peak of the knock waveform model is matched with the peak of the detected vibration waveform, the vibration intensity corresponding to the peak of the vibration waveform at the angle α (1) and the detected vibration waveform A knock waveform model is formed in advance and stored in the memory 202 based on the angle corresponding to the end of the section to be compared with, that is, the vibration intensity at the angle α (2). In the present embodiment, the knock waveform model may store in advance the vibration intensity up to an angle advanced by 10 degrees from the angle corresponding to the peak. In the present embodiment, the knock waveform model is represented by an exponential function expression to be described later. However, the present invention is not particularly limited to this, and an experimental measurement of a section to be compared with the detected vibration waveform is performed. The value may be stored in the memory 202 in advance.

  In the present embodiment, in the knock detection gate from the top dead center to 90 degrees, in particular, from the angle α (1) corresponding to the peak of the detected waveform to the angle α (2) advanced by a predetermined angle. And the detected waveform and the knock waveform model are compared. The two determination angles that define the determination section are not particularly limited to the angle α (1) and the angle α (2). For example, as long as the determination angle defines a section shorter than the knock detection gate. Good.

  Engine ECU 200 determines whether knocking has occurred or not by comparing the vibration waveform corrected as described above with the formed knock waveform model.

  With reference to FIG. 7, a control structure of a program executed by engine ECU 200 in the knocking determination device according to the present embodiment will be described.

  In step (hereinafter, step is abbreviated as S) 100, engine ECU 200 detects the intensity of vibration of engine 100 based on the signal transmitted from knock sensor 300. The intensity of vibration is represented by the output voltage value of knock sensor 300. The intensity of vibration may be represented by a value corresponding to the output voltage value of knock sensor 300. The intensity is detected from the top dead center to 90 degrees (90 degrees in crank angle) in the combustion stroke.

  In S102, engine ECU 200 integrates the output voltage value of knock sensor 300 (a value representing the intensity of vibration) every 5 degrees (only 5 degrees) in crank angle (hereinafter referred to as an integrated value). Is calculated. The integrated value is calculated for each vibration in the first frequency band A to the third frequency band C.

  In S104, engine ECU 200 synthesizes the vibration waveform of each frequency band. That is, among the calculated integrated values, the integrated values of vibrations in the first frequency band A to the third frequency band C are synthesized. Thereby, the vibration waveform of engine 100 is detected.

  In S106, engine ECU 200 normalizes the waveform using the maximum integrated value among the integrated values in the synthesized vibration waveform. Here, normalization of the waveform means, for example, dividing each integrated value by the maximum integrated value in the detected vibration waveform, thereby reducing the vibration intensity to 0-1 as shown in FIG. This is expressed by the number of dimensions. The value that divides each integrated value is not limited to the maximum integrated value.

  In S108, engine ECU 200 determines whether or not vibration corresponding to noise is superimposed on the accumulated waveform in a predetermined section. Specifically, as shown in FIG. 8 (A), engine ECU 200 oscillates the accumulated waveform at angle α (3) in a predetermined section from angle α (1) to angle α (2). The intensity A (3) is smaller than the corresponding vibration intensity C (3) of the knock waveform model, and the vibration intensity A (2) of the accumulated waveform at the angle α (2) is the corresponding vibration intensity of the knock waveform model. If it is smaller than C (3), it is determined that vibration corresponding to noise is not superimposed on the integrated waveform.

  Similarly, the vibration intensity A (3) of the accumulated waveform at the angle α (3) is larger than the corresponding vibration intensity C (3) of the knock waveform model, and the accumulated waveform at the angle α (2). If the vibration intensity A (2) is larger than the corresponding vibration intensity C (2) of the knock waveform model, it is determined that the vibration corresponding to the noise is not superimposed on the integrated waveform.

  On the other hand, as shown in FIG. 8B, the engine ECU 200 determines that the vibration intensity A (() of the accumulated waveform at the angle α (3) in a predetermined section from the angle α (1) to the angle α (2). 3) is smaller than the corresponding vibration intensity C (3) of the knock waveform model, and the vibration intensity A (2) of the accumulated waveform at the angle α (2) is the corresponding vibration intensity C (2 of the knock waveform model. If it is greater than (), it is determined that there is a section where the vibration intensity of the integrated waveform exceeds the vibration intensity of the knock waveform model and then exceeds, and it is determined that the vibration corresponding to the noise is superimposed on the integrated waveform. Returning to FIG. 7, if it is determined that the vibration corresponding to the noise is superimposed on the integrated waveform (YES in S108), the process proceeds to S110. If not (NO in S108), the process proceeds to S112.

  In S110, engine ECU 200 corrects the detected vibration waveform. Specifically, engine ECU 200 determines the vibration waveform based on vibration intensity A (1) at angle α (1) corresponding to the peak of the detected vibration waveform and vibration intensity A (2) at angle α (2). The attenuation factor λ (1) is calculated. Engine ECU 200 calculates vibration waveform attenuation factor λ (2) based on vibration intensity A (1) at angle α (1) and vibration intensity A (2) at angle α (3).

  The vibration waveform corresponding to knocking is expressed as (vibration) as shown by a thick line in FIG. 9, assuming that the attenuation rate is λ (1) for angles α (1) to α (2) corresponding to the peak of the vibration waveform. (Strength) = exp (−λ (1) × crank angle). Note that the angle zero in FIG. 9 corresponds to the angle α (1) corresponding to the peak of the detected vibration waveform. Also, the vibration intensity A (1) corresponding to the peak of the vibration waveform is “1” because it is normalized. Therefore, based on the vibration intensity B (1) corresponding to the angle α (2) −α (1) in FIG. 9, the attenuation rate λ (1) can be calculated from the above-described exponential function equation. Here, B (1) is a value obtained by normalizing the vibration intensity A (2) corresponding to the angle α (2) (that is, a value obtained by dividing A (2) by A (1)).

  Further, the vibration waveform corresponding to knocking has an attenuation rate of λ (2) for the angle α (1) to the angle α (3) corresponding to the peak of the vibration waveform, as shown by a thin line in FIG. (Vibration intensity) = exp (−λ (2) × crank angle). Note that the angle zero in FIG. 9 corresponds to the angle α (1) corresponding to the peak of the detected vibration waveform. Further, the vibration intensity A (1) corresponding to the peak of the vibration waveform is normalized, and is “1”. Therefore, based on the vibration intensity B (2) corresponding to the angle α (3) −α (1) in FIG. 9, the attenuation factor λ (2) can be calculated from the exponential function equation described above. Here, B (2) is a value obtained by normalizing the vibration intensity A (3) corresponding to the angle α (3) (a value obtained by dividing A (3) by A (1)).

  With the calculated average value λ (3) of λ (1) and λ (2) as the damping factor, the corrected vibration waveform (dashed line) is (vibration intensity) = exp (−λ (3) × crank angle ) Of the exponential function.

  In S112, engine ECU 200 calculates a correlation coefficient K that is a value relating to a deviation between the knock waveform model and the corrected vibration waveform. The deviation between the normalized vibration waveform and the knock waveform model in the state where the timing when the vibration intensity becomes maximum in the normalized vibration waveform and the timing when the vibration intensity becomes maximum in the knock waveform model are matched. By calculating the absolute value (deviation amount), the correlation coefficient K is calculated.

  As shown by the broken line in FIG. 9, the knock waveform model corresponding to the section to be compared with the corrected vibration waveform has (vibration intensity) = exp (−λ (4) × crank when the attenuation factor is λ (4). It can be expressed by an expression of an exponential function of (angle). The vibration intensity corresponding to the peak of the knock waveform model is “1”. Therefore, the knock waveform model sets the vibration intensity corresponding to the peak to 1, and sets the vibration intensity B (3) corresponding to the angle advanced by the angle α (2) −α (1) from the angle corresponding to the peak of the vibration intensity. The attenuation rate λ (4) is calculated by measurement through experiments or the like, and the above exponential function formula is stored in the memory 202 in advance as a knock waveform model.

  The sum of the absolute values of deviations from the top dead center to 90 degrees between the expression representing the normalized vibration waveform and the expression representing the knock waveform model is S ′, and the vibration intensity in the knock waveform model is integrated by the crank angle. When the value (area of the knock waveform model) is S, the correlation coefficient K is calculated by the equation K = (S−S ′) / S. Here, S ′ is normalized as shown in FIG. 10 by integrating the deviation between the expression representing the normalized vibration waveform and the expression representing the knock waveform model from the top dead center to 90 degrees. This is the sum of the areas of the figure (hatched line) surrounded by the lines indicating the above-mentioned formulas due to the deviation between the subsequent vibration waveform and the knock waveform model. Note that the method of calculating the correlation coefficient K is not limited to this.

  If it is determined in S108 that noise is not superimposed on the detected waveform, engine ECU 200 in S112 shows the measured value after normalization of the detected waveform and FIG. In the knock waveform model, the correlation coefficient K may be calculated in a state where the timings at which the vibration intensity is maximized are matched. Alternatively, the engine ECU 200 detects, in the detected waveform, the vibration intensity A (1) corresponding to the angle α (1) that is the start point of the determination section and the vibration intensity A ( 2), based on the vibration intensity corresponding to the start point of the determination section and the vibration intensity corresponding to the end point in the knock waveform model, It is also possible to calculate the waveform represented by the exponential function equation as described above, and calculate the correlation coefficient K of the waveform shape represented by both equations.

  Returning to FIG. 7, in S114, engine ECU 200 calculates knock magnitude N. If the calculated maximum value of the integrated value is P and 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 intensity N is N = It is calculated by the equation P × K / BGL. BGL is stored in the memory 202. The method for calculating knock magnitude N is not limited to this.

  In S116, engine ECU 200 determines whether knock magnitude N is greater than a predetermined determination value. If knock magnitude N is greater than a predetermined determination value (YES in S116), the process proceeds to S118. If not (NO in S116), the process proceeds to S122.

  In S118, engine ECU 200 determines that knocking has occurred in engine 100. In S120, engine ECU 200 retards the ignition timing. In S122, engine ECU 200 determines that knocking has not occurred in engine 100. In S124, engine ECU 200 advances the ignition timing.

  An operation of engine ECU 200 in the knocking determination device according to the present embodiment based on the above-described structure and flowchart will be described.

  When the driver turns on the ignition switch 312 and the engine 100 is started, the vibration intensity of the engine 100 is detected based on the signal transmitted from the knock sensor 300 (S100).

  Between the top dead center and 90 degrees in the combustion stroke, an integrated value every 5 degrees is calculated for each vibration of the frequency in the first frequency band A to the third frequency band C (S102). Of the calculated integrated values, the integrated values of vibrations from the first frequency band A to the third frequency band C are synthesized (S104). As a result, the vibration waveform of engine 100 is detected as a combined wave of vibrations from first frequency band A to third frequency band C.

  By detecting the vibration waveform by the integrated value every 5 degrees, it is possible to suppress detection of a vibration waveform having a complicated shape in which the vibration intensity changes finely. Of the integrated values in the vibration waveform detected in this way, the waveform is normalized using the maximum integrated value (S106).

  Here, it is assumed that each integrated value is divided by the integrated value from the angle α (1) to 5 degrees, and the vibration waveform is normalized. By normalization, the intensity of vibration in the vibration waveform is represented by a dimensionless number from 0 to 1. Thereby, it is possible to compare the detected vibration waveform with the knock waveform model regardless of the intensity of vibration. Therefore, it is not necessary to store a large number of knock waveform models corresponding to the vibration intensity, and the creation of the knock waveform model can be facilitated.

  In the detected waveform, after the vibration intensity at the angle α (3) after the angle α (1) falls below the vibration intensity of the knock waveform model of the corresponding angle, the vibration intensity at the angle α (2) corresponds. If there is a section exceeding the vibration intensity of the knock waveform model of the angle, it is determined that noise is superimposed on the detected waveform (YES in S108). When it is determined that noise is superimposed on the detected waveform, the attenuation rate is based on the vibration intensity A (1) at the angle α (1) and the vibration intensity A (2) at the angle α (2). λ (1) is calculated. Further, the attenuation rate λ (2) is calculated based on the vibration intensity A (1) at the angle α (1) and the vibration intensity A (3) at the angle α (2). The detected vibration waveform is corrected by the calculated average value λ (3) of the attenuation rates of λ (1) and λ (2) (S110).

  As shown in FIG. 10, the timing at which the vibration intensity is maximized in the corrected vibration waveform (thick line) matches the timing at which the vibration intensity is maximized in the calculated knock waveform model (thin line). Thus, S ′ (area of hatched portion) which is the sum of absolute values of deviation between the normalized vibration waveform and knock waveform model is calculated.

  Based on the calculated S ′ and the value S obtained by integrating the vibration intensity with the crank angle in the knock waveform model, the correlation coefficient K is calculated by K = (S−S ′) / S (S112). Thereby, the degree of coincidence between the detected vibration waveform and the knock waveform model can be expressed numerically and objectively determined.

  On the other hand, when it is determined that noise is not superimposed on the detected waveform (NO in S108), the timing at which the vibration intensity of the vibration waveform based on the actual measurement value is maximized and the vibration of the knock waveform model are maximized. In this state, S ′ that is the sum of absolute values of deviations between the normalized vibration waveform and the knock waveform model is calculated. A correlation coefficient K is calculated based on the calculated S ′ (S112).

  Knock strength N is calculated by dividing the product of correlation coefficient K calculated in this way and maximum value P of integrated values by BGL (S114). Thus, in addition to the degree of coincidence between the detected vibration waveform and the knock waveform model, it is possible to analyze in more detail whether or not the vibration of the engine 100 is vibration caused by knocking based on the intensity of vibration. it can. Here, it is assumed that knock magnitude K is calculated by dividing the product of correlation coefficient K and the integrated value from angle α (1) to the angle advanced by 5 degrees by BGL.

  If knock magnitude N is greater than a predetermined determination value (YES in S116), it is determined that knocking has occurred (S118), and the ignition timing is retarded (S120). Thereby, occurrence of knocking is suppressed.

  On the other hand, when knock intensity N is not greater than a predetermined determination value (NO in S116), it is determined that knocking has not occurred (S122), and the ignition timing is advanced (S124).

  As described above, according to the knock determination device for an internal combustion engine according to the present embodiment, the engine ECU detects the vibration waveform of the engine based on the signal transmitted from the knock sensor, and the vibration waveform and the knock waveform model And a correlation coefficient K is calculated. For example, a knock waveform model, which is a vibration waveform when knocking occurs, is created and stored in advance through experiments or the like, and whether or not knocking has occurred by comparing this knock waveform model with the detected waveform. Can be determined. In particular, if the detected waveform is not a waveform in which the vibration intensity continuously decreases starting from an angle corresponding to the peak of the waveform, it can be determined that vibration corresponding to noise is superimposed on the detected waveform. it can. If it is determined that the vibration corresponding to the noise is superimposed on the detected waveform, the engine ECU corrects the vibration intensity so that the vibration intensity continuously decreases starting from the angle corresponding to the peak of the waveform. . The engine ECU determines whether or not engine knocking has occurred based on the result of comparing the corrected waveform and the knock waveform model. When it is determined that the vibration corresponding to the noise is superimposed, the vibration corresponding to knocking is corrected by correcting the waveform so that the vibration intensity continuously decreases starting from the angle corresponding to the peak of the waveform. When a waveform including is detected, the deterioration of the correlation coefficient of the shape with the knock waveform model can be suppressed. Therefore, it is possible to provide a knock determination device that can accurately determine whether knock has occurred in the internal combustion engine.

  In addition, when it is determined that the vibration corresponding to the noise is not superimposed, the correlation coefficient is deteriorated due to the noise by comparing the measured value of the detected waveform with the knock waveform model. It can be determined whether knocking has occurred in the engine. Therefore, it can be accurately determined whether knocking has occurred in the engine.

  Preferably, the angle α (1) and the angle α (2) are the first half of the detection gate section (section from the top dead center to 90 degrees). In the second half of the gate section, since the output of the signal corresponding to knocking is small, it is difficult to distinguish it from BGL. Therefore, since the angle α (1) and the angle α (2) are the first half of the gate section, the signal output is also large, so that the accuracy of separating the vibration corresponding to noise and the vibration corresponding to knocking is improved. Can do.

<Second Embodiment>
Hereinafter, an internal combustion engine knock determination device according to a second embodiment of the present invention will be described. The knocking determination device for an internal combustion engine according to the present embodiment is different from the configuration of the knocking determination device for an internal combustion engine according to the first embodiment described above in the control structure of a program executed by engine ECU 200. The other configuration is the same as that of the knock determination device for the internal combustion engine according to the first embodiment described above. They are given the same reference numerals. Their functions are the same. Therefore, detailed description thereof will not be repeated here.

  In the present embodiment, it is determined whether there are one or two portions corresponding to the vibration peak in a section predetermined for the detected waveform. If there are two portions corresponding to the vibration peak, engine ECU 200 determines that the vibration waveform detected by knock sensor 300 is not a waveform in which the vibration intensity continuously decreases starting from the angle corresponding to the peak of the vibration waveform. It is determined that the vibration corresponding to the noise is superimposed on the detected waveform.

  In the present embodiment, if there are two portions corresponding to vibration peaks, the waveform after each vibration peak is compared with the knock waveform model, and either of the correlation coefficients of the shapes of the two is compared. It is characterized in that the knock intensity corresponding to the higher peak is calculated. In the following description, it is assumed that one vibration peak is a single peak, and two vibration peaks are two peaks.

  Specifically, as shown in FIG. 11, it is assumed that the detected waveform (solid line) includes vibration corresponding to knocking and vibration corresponding to seating noise of the intake valve 116 or the exhaust valve 118. When engine ECU 200 extracts three in descending order from the largest vibration intensity in a predetermined section of the detected waveform, engine ECU 200 determines whether or not the three angles corresponding to the extracted vibration intensity are continuous angles. Based on this, it is determined whether the detected waveform is one mountain or two mountains in a predetermined section.

  When engine ECU 200 determines that there are two peaks, the waveform of the determination section is compared with the knock waveform model (broken line) from the angle corresponding to each peak of the two peaks, and the waveform of the two peaks and the knock waveform model are compared. The correlation coefficient of the shape is calculated. Engine ECU 200 calculates the knock strength using the numerical value with the larger calculated correlation coefficient, and makes a knock determination.

  Hereinafter, a control structure of a program executed by engine ECU 200 in the present embodiment will be described with reference to FIG.

  In the flowchart shown in FIG. 12, the same steps as those in the flowchart shown in FIG. The processing is the same for them. Therefore, detailed description thereof will not be repeated here.

  In S200, engine ECU 200 starts a peak determination process for vibration waveforms, which will be described later. In S202, engine ECU 200 determines whether the detected waveform is a single mountain or two mountains in a predetermined section as a result of the single mountain determination process in S200. The “predetermined section” is not particularly limited as long as it is a section smaller than the knock detection gate, but is preferably the first half section of the knock detection gate. This is because the vibration corresponding to knocking has a vibration peak in the first half section of the knock detection gate. If it is determined that the detected waveform is a mountain in a predetermined section (YES in S202), the process proceeds to S112. If not (NO in S202), the process proceeds to S204.

  In S204, engine ECU 200 corrects the vibration waveform. Specifically, in each of the two peaks, as described in FIG. 9 of the first embodiment described above, when the angle α (1) corresponding to the peak of vibration corresponds to the angle α (1). Vibration intensity A (1), vibration intensity A (2) corresponding to angle α (2) advanced 10 degrees from angle α (1), and angle α (3) advanced 5 degrees from angle α (1) Based on the corresponding vibration intensity A (3), an average value λ (3) of the damping rate is calculated and corrected by an exponential function equation of (vibration intensity) = exp (−λ (3) × crank angle). Represents a vibration waveform. In addition, each crank angle corresponding to two mountains can be calculated in a single mountain determination process described later.

  In S206, engine ECU 200 calculates the correlation coefficient between the expressions representing the two peaks and the shape of the knock waveform model. Since the correlation coefficient calculation method is the same as the correlation coefficient calculation method described in the first embodiment, details thereof will not be repeated. In S208, engine ECU 200 selects the larger one of the calculated correlation coefficients as correlation coefficient K. After S208, the process proceeds to S114.

  Hereinafter, with reference to FIG. 13, a control structure of a program for determining a peak of a vibration waveform executed by engine ECU 200 in the present embodiment will be described.

  In S300, engine ECU 200 determines the angle corresponding to the largest vibration intensity (hereinafter referred to as the first vibration intensity) and the second largest vibration intensity (hereinafter referred to as the following vibration intensity) in a predetermined section of the detected waveform. The angle corresponding to the second vibration intensity) and the angle corresponding to the third largest vibration intensity (hereinafter referred to as the third vibration intensity) are extracted, and the extracted three points are continuous. It is determined whether or not. That is, in the present embodiment, the vibration intensity is represented by an integrated value every 5 degrees, and engine ECU 200 determines whether or not the extracted three points are angles that are continuous at intervals of 5 degrees. If determined to be continuous (YES in S300), the process proceeds to S301. If not (NO in S300), the process proceeds to S304.

  In S301, engine ECU 200 determines whether or not the third vibration intensity is in the center. That is, engine ECU 200 determines whether or not the angle corresponding to the third vibration intensity is between the angle corresponding to the first vibration intensity and the angle corresponding to the second vibration intensity. If the third vibration intensity is in the center (YES in S301), the process proceeds to S303. If not (NO in S301), the process proceeds to S302.

  In S302, engine ECU 200 determines that the detected vibration waveform in the predetermined section is a peak waveform having a vibration peak at an angle corresponding to the first vibration intensity.

  In S303, engine ECU 200 determines that the vibration waveform detected in a predetermined section has two peaks each having a vibration peak at an angle corresponding to the first vibration intensity and an angle corresponding to the second vibration intensity. It is determined that the waveform is

  In S304, engine ECU 200 determines whether or not only the angle corresponding to the first vibration intensity and the angle corresponding to the second vibration intensity are consecutive among the three extracted points. If it is determined that only the angle corresponding to the first vibration intensity and the angle corresponding to the second vibration intensity are continuous (YES in S304), the process proceeds to S306. If not (NO in S304), the process proceeds to S308.

  In S306, engine ECU 200 determines that the vibration waveform detected in a predetermined section has two peaks each having a vibration peak at an angle corresponding to the first vibration intensity and an angle corresponding to the third vibration intensity. It is determined that the waveform is

  In S308, engine ECU 200 determines whether or not only the angle corresponding to the second vibration intensity and the angle corresponding to the third vibration intensity among the extracted three points are continuous. If it is determined that only the angle corresponding to the second vibration intensity and the angle corresponding to the third vibration intensity are continuous (YES in S308), the process proceeds to S310. If not (NO in S308), the process proceeds to S312.

  In S310, engine ECU 200 determines that the vibration waveform detected in the predetermined section has two peaks each having a vibration peak at an angle corresponding to the first vibration intensity and an angle corresponding to the second vibration intensity. It is determined that the waveform is

  In S312, engine ECU 200 determines whether or not only the angle corresponding to the first vibration intensity and the angle corresponding to the third vibration intensity are consecutive among the extracted three points. If it is determined that only the angle corresponding to the first vibration intensity and the angle corresponding to the third vibration intensity are continuous (YES in S312), the process proceeds to S314. If not (NO in S312), the process proceeds to S316.

  In S314, engine ECU 200 determines that the vibration waveform detected in the predetermined section has a vibration peak at an angle corresponding to the first vibration intensity and an angle corresponding to the second vibration intensity. Judged to be a mountain waveform.

  In S316, engine ECU 200 determines that the vibration waveform detected in the predetermined section has a vibration peak at an angle corresponding to the first vibration intensity and an angle corresponding to the second vibration intensity. Judged to be a mountain waveform. In this case, there is a portion corresponding to the vibration peak at an angle corresponding to the vibration intensity at the third position, but the peak due to the vibration intensity at the third position is smaller than the vibration intensity at the first and second positions. As a matter of fact, engine ECU 200 determines that the waveform has two peaks, assuming that there is a vibration peak at angles corresponding to the first and second vibration strengths.

  The operation of the knock determination device for the internal combustion engine according to the present embodiment based on the structure and flowchart as described above will be described.

  When the driver turns on the ignition switch 312 and the engine 100 is started, the vibration intensity of the engine 100 is detected based on the signal transmitted from the knock sensor 300 (S100).

  Between the top dead center and 90 degrees in the combustion stroke, an integrated value every 5 degrees is calculated for each vibration of the frequency in the first frequency band A to the third frequency band C (S102). Of the calculated integrated values, the integrated values of vibrations from the first frequency band A to the third frequency band C are synthesized (S104). As a result, the vibration waveform of engine 100 is detected as a combined wave of vibrations from first frequency band A to third frequency band C.

  By detecting the vibration waveform by the integrated value every 5 degrees, it is possible to suppress detection of a vibration waveform having a complicated shape in which the vibration intensity changes finely. Of the integrated values in the vibration waveform detected in this way, the waveform is normalized using the maximum integrated value (S106).

  Here, it is assumed that each integrated value is divided by the integrated value from the angle α (1) to 5 degrees, and the vibration waveform is normalized. By normalization, the intensity of vibration in the vibration waveform is represented by a dimensionless number from 0 to 1. Thereby, it is possible to compare the detected vibration waveform with the knock waveform model regardless of the intensity of vibration. Therefore, it is not necessary to store a large number of knock waveform models corresponding to the vibration intensity, and the creation of the knock waveform model can be facilitated.

  Then, the peak determination process of the detected waveform is started (S200), the angles corresponding to the three extracted vibration intensities are consecutive (YES in S300), and the third vibration intensity is not the center. (NO in S301), it is determined that the detected waveform is a single waveform (YES in S302 and S202). Then, the timing at which the integrated value of the vibration intensity of the detected waveform is maximized coincides with the timing at which the vibration intensity of the knock waveform model is maximized, and in this state, the normalized vibration waveform and knock waveform model are S ′, which is the sum of absolute values of deviations, is calculated. At this time, S ′ is a sum of absolute values of deviations between the normalized vibration waveform and the knock waveform model in the determination section from the angle corresponding to the vibration peak to the angle advanced by 10 degrees. Is done.

  Based on the calculated S ′ and the value S obtained by integrating the intensity of vibration in the knock waveform model in this determination section, the correlation coefficient K is obtained by K = (S−S ′) / S based on the knock waveform model. Is calculated (S112). Thereby, the degree of coincidence between the detected vibration waveform and the knock waveform model can be expressed numerically and objectively determined.

  On the other hand, the angle corresponding to the extracted three vibration intensities is a continuous angle (YES in S300), and if the third vibration intensity is in the center (YES in S301), the detected waveform is first. It is determined that the waveform has two peaks having a vibration peak at an angle corresponding to the vibration intensity of 2 and an angle corresponding to the vibration intensity of the second place (S303). At this time, the vibration waveform is corrected in the determination section from the respective angles corresponding to the peaks of the two peaks to the angle advanced by 10 degrees (S204). As a result of comparison with the knock waveform model in this determination section, both Are respectively calculated (S206), and the larger one is selected as the correlation coefficient K (S208).

  Furthermore, if only the angles corresponding to the first and second vibration strengths are continuous (YES in S304), the detected waveform corresponds to the angle corresponding to the first vibration strength and the third vibration strength. It is determined that the two waveforms have vibration peaks at angles (NO in S306 and S202). At this time, the vibration waveform is corrected in the determination section from the respective angles corresponding to the peaks of the two peaks to the angle advanced by 10 degrees (S204). As a result of comparison with the knock waveform model in this determination section, both Are respectively calculated (S206), and the larger one is selected as the correlation coefficient K (S208).

  If only the angles corresponding to the second and third vibration intensity are continuous (YES in S308), the detected waveform corresponds to the angle corresponding to the first vibration intensity and the second vibration intensity. It is determined that the two waveforms have vibration peaks at angles (NO in S310 and S202). At this time, the vibration waveform is corrected in the determination section from each angle corresponding to the peak of the two peaks to an angle advanced by 10 degrees (S204), and as a result of comparison with the knock waveform model of this determination section, The correlation coefficient of both shapes is calculated (S206), and the larger one is selected as the correlation coefficient K (S208).

  Further, as shown in FIG. 14, if only the angles corresponding to the first and third vibration strengths are continuous (YES in S312), the detected waveform has an angle corresponding to the first vibration strength and 2 It is determined that the waveform has two peaks having a vibration peak at an angle corresponding to the vibration intensity of the position (NO in S314 and S202). At this time, the vibration waveform is corrected in the determination section from the respective angles corresponding to the peaks of the two peaks to the angle advanced by 10 degrees (S204), and as a result of comparison with the knock waveform model in this determination section, both shapes Are respectively calculated (S206), and the larger one is selected as the correlation coefficient K (S208).

  If the angles corresponding to the first and third vibration strengths are not continuous (S312), that is, if neither the first to third positions are continuous, the detected waveform corresponds to the first vibration strength. And an angle corresponding to the vibration intensity at the second place are determined to be two peaks having a substantial vibration peak (NO in S316 and S202). At this time, the vibration waveform is corrected in the determination section from each angle corresponding to the peak of the two peaks to the angle advanced by 10 degrees (S204), and the knock waveform model in this determination section was compared. As a result, the correlation coefficient of both shapes is calculated (S206), and the larger one is selected as the correlation coefficient K (S208).

  In the correction of the vibration waveform, the attenuation factor λ (1) is calculated based on the vibration intensity A (1) at the angle α (1) corresponding to the peak and the vibration intensity A (2) at the angle α (2). The Further, the attenuation rate λ (2) is calculated based on the vibration intensity A (1) at the angle α (1) and the vibration intensity A (3) at the angle α (2). The detected vibration waveform is corrected by the average value λ (3) of the calculated attenuation rates of λ (1) and λ (2).

  Knock strength N is calculated by dividing the product of correlation coefficient K calculated or selected in this way and maximum integrated value P by BGL (S114). Thus, in addition to the degree of coincidence between the detected vibration waveform and the knock waveform model, it is possible to analyze in more detail whether or not the vibration of the engine 100 is vibration caused by knocking based on the intensity of vibration. it can. Here, it is assumed that knock magnitude K is calculated by dividing the product of correlation coefficient K and the integrated value from angle α (1) to the angle advanced by 5 degrees by BGL.

  If knock magnitude N is greater than a predetermined determination value (YES in S116), it is determined that knocking has occurred (S118), and the ignition timing is retarded (S120). Thereby, occurrence of knocking is suppressed.

  On the other hand, when knock intensity N is not greater than a predetermined determination value (NO in S116), it is determined that knocking has not occurred (S122), and the ignition timing is advanced (S124).

  As described above, according to the knock determination device for an internal combustion engine according to the present embodiment, the engine ECU does not have an angle corresponding to the vibration intensity extracted in descending order from the largest vibration intensity of the detected waveform. Since the waveform does not have a continuously decreasing vibration intensity starting from the angle corresponding to the peak, it is determined that the vibration corresponding to the noise is superimposed on the detected waveform. When it is determined that the vibration corresponding to the noise is superimposed on the detected waveform, the engine ECU calculates a correlation coefficient between the vibration waveform after the angle corresponding to each peak and the knock waveform model, It is determined whether knocking has occurred in the engine based on the larger correlation coefficient. Therefore, it is possible to provide a knock determination device that can accurately determine whether or not knocking has occurred in the internal combustion engine even if noise is superimposed on the vibration corresponding to knocking.

  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 controlled by the knock determination apparatus which concerns on 1st Embodiment. It is a figure which shows the frequency of the vibration which generate | occur | produces with an engine. It is a figure which shows the knock waveform model memorize | stored in memory of engine ECU. It is a figure which shows the vibration waveform and knock waveform model in a detection gate. It is a figure (the 1) which shows the vibration waveform containing the vibration corresponding to noise, and a knock waveform model. It is a figure which shows the corrected vibration waveform. It is a flowchart which shows the control structure of the program which engine ECU of the knock determination apparatus which concerns on 1st Embodiment performs. FIG. 10 is a diagram (part 2) illustrating a vibration waveform including a vibration corresponding to noise and a knock waveform model; It is a figure which shows the corrected vibration waveform and knock waveform model after normalization. It is a figure which shows the timing which compares the vibration waveform after normalization, and a knock waveform model. It is a figure (the 1) which shows the vibration waveform of two mountains. It is a flowchart which shows the control structure of the program which engine ECU of the knock determination apparatus which concerns on 2nd Embodiment performs. It is a flowchart which shows the control structure of the program of the mountain determination process which engine ECU of the knock determination apparatus which concerns on 2nd Embodiment performs. It is a figure (the 2) which shows the vibration waveform of two mountains.

Explanation of symbols

  100 engine, 104 injector, 106 spark plug, 110 crankshaft, 116 intake valve, 118 exhaust valve, 120 pump, 200 engine ECU 200, 300 knock sensor, 302 water temperature sensor, 304 timing rotor, 306 crank position sensor, 308 throttle opening Sensor.

Claims (6)

A knock determination device for an internal combustion engine,
Crank angle detecting means for detecting the crank angle of the internal combustion engine;
Waveform detecting means for detecting a waveform of vibration of the internal combustion engine during a predetermined crank angle;
Storage means for storing in advance a waveform of vibration of the internal combustion engine during the predetermined crank angle;
Based on whether or not the detected waveform is a waveform in which the vibration intensity continuously decreases starting from an angle corresponding to the peak of the waveform, vibration corresponding to noise is superimposed on the detected waveform. Noise determining means for determining whether or not
When it is determined that the vibration corresponding to the noise is not superimposed on the detected waveform, the internal combustion engine is compared with the result of comparing the detected waveform with the waveform stored in the storage unit. A knocking determination device for an internal combustion engine, comprising knocking determination means for determining whether knocking has occurred. The waveform stored in the storage means is a waveform in which the vibration intensity continuously decreases starting from an angle corresponding to the peak of the waveform,
The noise determination unit determines that the vibration corresponding to the noise is superimposed on the detected waveform when the detected waveform and the waveform stored in the storage unit have a crossing portion. The knock determination device for an internal combustion engine according to claim 1, comprising the following means.   The noise judging means is means for judging that the vibration corresponding to the noise is superimposed if the angle corresponding to the vibration intensity extracted in descending order from the largest vibration intensity of the detected waveform is not continuous. The knock determination device for an internal combustion engine according to claim 1, comprising: When it is determined that the vibration corresponding to the noise is superimposed on the detected waveform, the knock determination device generates a waveform in which the vibration intensity continuously decreases starting from an angle corresponding to the peak of the waveform. And further includes a correction means for correcting so that
The knocking determination means includes means for determining whether or not knocking has occurred in the internal combustion engine based on a result of comparing the corrected waveform and a waveform stored in the storage means. Item 4. The knock determination device for an internal combustion engine according to any one of Items 1 to 3.   The correction means uses the average value of the change rates of a plurality of waveforms formed based on a reference angle serving as a reference in the detected waveform and a vibration intensity at each of a plurality of angles different from the reference angle. 5. The knock determination device for an internal combustion engine according to claim 4, further comprising means for correcting the detected waveform. The reference angle is an angle corresponding to a peak of vibration intensity in the detected waveform,
The correction means includes a change rate of a waveform formed based on the vibration intensity at the reference angle and the vibration intensity at a first angle different from the reference angle, the vibration intensity at the reference angle, and the reference angle. And means for correcting the detected waveform by an average value of the rate of change of the waveform formed based on the vibration intensity at the second angle different from
6. The knock determination device for an internal combustion engine according to claim 5, wherein the first angle and the second angle are different, and the first angle and the second angle are larger than the reference angle.

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