JP2006307665A - Knocking determining device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately determine whether or not knocking is generated. <P>SOLUTION: An engine ECU executes a program including a step (S108) of correcting a waveform detected as a waveform of vibration caused by the knocking, a step (S110) of calculating a knock waveform model stored in a memory as the waveform of the vibration caused by the knocking, a step (S114) of calculating knock strength N on the basis of a result of comparing the corrected waveform with the calculated knock waveform model, a step (S118) of determining that the knocking is generated when the knock strength N is larger than a predetermined determining value (YES in S116), and a step (S122) of determining that the knocking is not generated when the knock strength N is not larger than the predetermined determining value (NO in S116). <P>COPYRIGHT: (C)2007,JPO&INPIT

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 Laid-Open No. 2001-227400 (Patent Document 1) discloses a knock control device for an internal combustion engine that can accurately determine the presence or absence of occurrence of knocking. The 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 with respect to 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 of the present invention is to provide a knock determination device that can accurately determine whether knock has occurred.

  A knock determination device according to a first aspect of the present invention is a knock determination device for 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 preliminarily storing a vibration waveform of the internal combustion engine during the crank angle, and vibration intensity at a first angle and a second angle between predetermined crank angles in the detected waveform Determination means for determining whether or not knocking has occurred in the internal combustion engine based on the result of comparing the waveform formed based on the waveform and the waveform stored in the storage means.

  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 a first angle (for example, a detected waveform) between the predetermined crank angles in the detected waveform. The waveform formed based on the vibration intensity at the second angle (for example, an angle advanced by a predetermined angle from the angle corresponding to the peak value) and the stored waveform were compared. Based on the result, it is determined whether or not knocking has occurred in the internal combustion engine. As a result, a knock waveform model, which is a vibration waveform when knocking occurs, is created and stored in advance by, for example, experiments, and knocking occurs by comparing this knock waveform model with the detected waveform. It can be determined whether or not. In particular, in the detected waveform, the waveform formed based on the vibration intensity at the first angle and the second angle between the predetermined crank angles is compared with the stored waveform. Thus, for example, if the first angle and the second angle are such that vibrations other than knocking are not superimposed, a waveform in which vibrations other than knocking are not superimposed can be detected. It is possible to provide a knocking determination device capable of accurately determining whether or not.

  In the knocking determination device according to the second invention, in addition to the configuration of the first invention, the stored waveform is formed based on the vibration intensity of the angles respectively corresponding to the first angle and the second angle. Is the waveform to be played.

  According to the second invention, the stored waveform is a waveform formed on the basis of the vibration intensity at angles corresponding to the first angle and the second angle, respectively. The vibration intensity at a first angle (for example, a peak value of the detected waveform) and a second angle (for example, an angle advanced by a predetermined angle from the angle corresponding to the peak value) in the detected waveform The waveform formed based on the waveform is compared with the waveform formed based on the vibration intensity of the angle respectively corresponding to the first angle and the second angle in the waveform stored in advance. For example, if the first angle and the second angle are such that vibrations other than knocking do not overlap, a waveform in which vibrations other than knocking do not overlap can be detected. At this time, the knock waveform model is also formed on the basis of the vibration intensity at the angles corresponding to the first angle and the second angle, respectively, and the detected waveform is compared with the formed knock waveform model. It is possible to accurately determine whether knocking has occurred in the engine.

  In the knock determination device according to the third aspect of the invention, in addition to the configuration of the first or second aspect, the first angle and the second angle are vibrations different from vibrations corresponding to knocking in vibrations corresponding to knocking. The angle is such that vibrations generated due to the operation of the internal combustion engine do not overlap.

  According to the third invention, the first angle and the second angle are different from the vibration corresponding to knocking on the vibration corresponding to knocking, and the vibration generated due to the operation of the internal combustion engine is superimposed. Do not angle. When a waveform is detected based on the first angle and the second angle, a waveform in which vibrations other than knocking are not superimposed can be detected.

  In the knock determination device according to the fourth invention, in addition to the configuration of any one of the first to third inventions, the vibration intensity in the detected waveform is between the first angle and the second angle. Includes the angle corresponding to the peak.

  According to the fourth invention, the angle corresponding to the peak of the vibration intensity in the detected waveform is included between the first angle and the second angle. In the detected waveform, it is possible to accurately determine whether or not knocking has occurred in the internal combustion engine by determining knocking based on a waveform including a vibration peak.

  In the knock determination device according to the fifth invention, in addition to the configuration of the fourth invention, either the first angle or the second angle is an angle corresponding to the peak of the vibration intensity in the detected waveform. is there.

  According to the fifth invention, in the detected waveform, the waveform is formed based on the vibration intensity corresponding to the peak and the vibration intensity corresponding to the angle advanced from the angle corresponding to the peak by a predetermined angle. Based on this, it is possible to accurately determine whether or not knocking has occurred in the internal combustion engine by determining knocking.

  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.

  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 the signals transmitted from each sensor and ignition switch 312, the map and program stored in memory 202, and controls the 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 determines the vibration intensity at angles α (1) and α (2) between the crank angles from top dead center to 90 degrees in the vibration waveform detected by knock sensor 300. A characteristic is that a determination is made as to whether or not knocking has occurred in the engine 100 based on the result of comparing the formed vibration waveform with the knock waveform model. The angle α (1) is an angle corresponding to the peak of the detected vibration waveform in the present embodiment, but is not particularly limited. Further, in the present embodiment, it is assumed that the vibration waveform is formed based on the respective vibration intensities at the angle α (1) and the angle α (2) between the top dead center and 90 degrees. It is not limited to -90 degrees.

  When comparing the detected vibration waveform (solid line) and the knock waveform model (thin line) as shown in FIG. 4, if vibrations other than knocking are superimposed, the vibration waveform at the crank angle α (3) is knocked. Since a deviation from the waveform model occurs, 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.

  In the present invention, 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 (1) corresponding to the peak are determined in advance. The detected vibration waveform is corrected based on the vibration intensity A (2) corresponding to the angle α (2) advanced by the angle. The predetermined angle is not particularly limited as long as the angle α (2) is an angle after the peak value and does not overlap vibration other than knocking. In the present embodiment, the predetermined angle is, for example, 10 degrees.

  On the other hand, for the knock waveform model, as shown in FIG. 4, when the peak of the knock waveform model is matched with the peak of the detected vibration waveform, the angle α Based on the vibration intensity corresponding to the peak of the vibration waveform in (1) and the vibration intensity corresponding to angle α (2) advanced by a predetermined angle from angle α (1), a knock waveform model (thin line) Form.

  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. 5, 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 vibration intensity A (1) corresponding to angle α (1) corresponding to the detected peak of the vibration waveform and angle α advanced by a predetermined angle from angle α (1). The vibration waveform is corrected based on the vibration intensity A (2) corresponding to (2).

  The vibration waveform corresponding to knocking is expressed by (vibration intensity) = exp (−), as shown by a thick line in FIG. λ (1) × crank angle). Note that the angle zero in FIG. 6 corresponds to the angle α (1) corresponding to the peak of the detected vibration waveform. Further, since the vibration intensity A (1) corresponding to the peak of the vibration waveform is normalized, it is “1”. Therefore, the attenuation factor λ (1) can be calculated based on the vibration intensity B (1) corresponding to the angle α (2) −α (1) in FIG. Here, B (1) is a value obtained by normalizing the vibration intensity A (2) corresponding to the angle α (2) (a value obtained by dividing A (2) by A (1)).

  In this way, by calculating λ (1), the vibration waveform corresponding to knocking is represented and corrected by the above-described equation.

  Returning to FIG. 5, in S110, engine ECU 200 calculates a knock waveform model. As for the knock waveform model, similarly to the detected vibration waveform, assuming that the attenuation rate is λ (2), the knock waveform model has (vibration intensity) = exp (−λ (2) as shown by a thin line in FIG. ) × crank angle). Note that the angle zero in FIG. 6 corresponds to the angle corresponding to the peak of the knock waveform model. The vibration intensity corresponding to the peak of the knock waveform model is “1”. Therefore, the vibration intensity B (2) corresponding to the angle advanced by the angle α (2) −α (1) from the angle corresponding to the peak of the knock waveform model is read from the knock waveform model stored in the memory 202, and The attenuation factor λ (2) can be calculated.

  Therefore, engine ECU 200 determines λ (2) based on vibration waveform peak value “1” stored in memory 202 and vibration intensity B (2) corresponding to angle α (2) −α (1). To calculate the knock waveform model represented by the above-described equation.

  In S112, engine ECU 200 calculates a correlation coefficient K that is a value relating to a deviation between the corrected vibration waveform and the corrected knock waveform model. 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.

  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. 7 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 enclosed figures (hatched lines) 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.

  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.

  Based on the vibration intensity at the angle α (1) and the vibration intensity at the angle α (2), the attenuation factor λ (1) is calculated, and the vibration waveform is corrected as shown by the thick line in FIG. 7 (S108). ).

  Then, in the knock waveform model stored in advance, the vibration intensity B (2) corresponding to the angle α (2) −α (1) is read, the attenuation rate λ (2) is calculated, and the knock waveform model is obtained. An expression representing (thin line) is calculated (S110).

  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). S ′ (area of the hatched portion) that is the sum of absolute values of deviations between the waveform and the 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.

  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 To calculate a correlation coefficient. 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, in the detected waveform, the waveform formed based on the vibration intensity at the angle α (1) and the angle α (2) between the predetermined crank angles is compared with the knock waveform model. As a result, when the angle α (1) and the angle α (2) are such that vibrations other than knocking do not overlap, it is possible to detect a waveform in which vibrations other than knocking are not mixed. It is possible to provide a knocking determination device capable of accurately determining whether or not it has occurred.

  The knock waveform model is also formed based on the vibration intensity at the angles corresponding to the angle α (1) and the angle α (2), respectively, similarly to the detected vibration waveform. Whether knocking occurred in the internal combustion engine by comparing the waveform formed based on the vibration intensity at the angle α (1) and the angle α (2) in the detected waveform with the formed knock waveform model It is possible to accurately determine whether or not.

  Preferably, an angle corresponding to the peak of the vibration intensity of the detected waveform is included between the angle α (1) and the angle α (2). In this way, since knocking can be determined based on the waveform corresponding to the peak, it is possible to accurately determine whether knocking has occurred in the engine.

  More preferably, as described in the present embodiment, the angle α (1) is desirably an angle corresponding to the peak. In this way, the detected waveform is formed based on the peak value and the vibration intensity corresponding to the angle α (2) advanced from the angle α (1) corresponding to the peak value by a predetermined angle. By determining knocking based on the vibration waveform, it can be accurately determined whether or not knocking has occurred in the engine.

  More 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.

  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 embodiment of this invention. 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 flowchart which shows the control structure of the program which engine ECU performs. It is a figure which shows the corrected vibration waveform and the calculated knock waveform model. It is a figure which shows the timing which compares the vibration waveform after normalization, and a knock waveform model.

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 (5)

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;
In the detected waveform, the waveform formed based on the vibration intensity at the first angle and the second angle between the predetermined crank angles is compared with the waveform stored in the storage means And a determination means for determining whether or not knocking has occurred in the internal combustion engine based on the result.   2. The knock determination device for an internal combustion engine according to claim 1, wherein the stored waveform is a waveform formed based on vibration intensity at an angle corresponding to each of the first angle and the second angle.   The first angle and the second angle are vibrations that are different from vibrations corresponding to knocking and vibrations caused by operation of the internal combustion engine are not superimposed on vibrations corresponding to knocking. The knock determination device for an internal combustion engine according to claim 1 or 2, wherein   The knock determination of the internal combustion engine according to any one of claims 1 to 3, wherein an angle corresponding to a peak of vibration intensity in the detected waveform is included between the first angle and the second angle. apparatus.   5. The knock determination device for an internal combustion engine according to claim 4, wherein one of the first angle and the second angle is an angle corresponding to a peak of vibration intensity in the detected waveform.

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