JP2006307710A - Knocking determining device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately determine whether knocking is generated. <P>SOLUTION: An engine ECU executes a program including steps of: (S120) calculating a correlation coefficient K by comparing a knock waveform model with a vibration waveform of an engine detected on the basis of an integral value of integrating an output voltage value of a knock sensor; (S122) calculating knock strength N by dividing the product of the calculated correlation coefficient K and a maximum value P of the integral value in the detected vibration waveform by BGL set so as to become large as an engine speed of the engine becomes high; (S126) determining that the knocking is generated when the knock strength N is larger than a determining value (YES in S124); and (S130) determining that the knocking is not generated when the knock strength N is not larger than the determining value (NO in S124). <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. 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 value detection unit that detects a peak value in the occurrence period detected by the occurrence period detection unit, and occurrence of knock occurrence in the internal combustion engine based on the relationship between the occurrence period and the peak value 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 has occurred when the ratio between the peak value and the generation period is within a predetermined range.

According to the knock control device for an internal combustion engine described in this publication, a vibration waveform signal generated in the internal combustion engine is detected by the signal detection unit, and a generation period during which the vibration waveform signal is equal to or greater than a predetermined value and its peak value Are detected by the occurrence period detector and the peak value detector, respectively. Thus, by knowing the generation period of the vibration waveform signal and its peak value, the knock determination unit determines whether or not knocking has occurred in the internal combustion engine, and the operation state of the internal combustion engine is controlled according to the knock determination result. The The knock determination unit has a waveform shape in which the peak value is large when the ratio between the peak value and the generation period is within a predetermined range, that is, the generation period of the predetermined length of the vibration waveform signal. Sometimes 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, the intensity (magnitude) of vibration detected by the internal combustion engine includes the intensity of mechanical vibration of the internal combustion engine itself in addition to the intensity of vibration caused by knocking. The intensity of mechanical vibration of an internal combustion engine tends to increase as the load on the internal combustion engine increases or the rotational speed increases. Therefore, in the knock control device for an internal combustion engine described in Japanese Patent Laid-Open No. 2001-227400, it is necessary to determine whether or not knocking has occurred using a threshold value corresponding to the load and the rotational speed of the internal combustion engine. For this reason, there is a problem that the accuracy of the knocking determination may deteriorate due to a sudden change in the threshold used for the determination, particularly in a transient state in which the load and the rotational speed of the internal combustion engine change frequently.

  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.

  An internal combustion engine knock determination device according to a first aspect of the present invention is an intensity detection means for detecting a first value relating to a vibration intensity of the internal combustion engine, and a crank angle detection means for detecting a crank angle of the internal combustion engine. A waveform detecting means for detecting a vibration waveform of the internal combustion engine at a predetermined interval with respect to the crank angle based on the first value; a means for previously storing the vibration waveform of the internal combustion engine; Based on the result of comparing the detected waveform with the stored waveform, means for calculating a value related to the deviation between the detected waveform and the stored waveform, and based on the value related to the deviation and the first value The calculation means for correcting the calculated value with the second value and calculating the third value relating to the vibration intensity of the internal combustion engine and the fourth value relating to the vibration intensity of the internal combustion engine are stored in advance. Means for , Including on the basis of a result of comparison with a third value and a fourth value, and a determination means for determining whether or not knocking has occurred in the internal combustion engine.

  According to the first invention, the first value related to the vibration intensity is detected, and the vibration waveform of the internal combustion engine is detected. The detected waveform is compared with a waveform stored in advance as a vibration waveform when knocking occurs in the internal combustion engine, for example, and a value relating to a deviation between the detected waveform and the stored waveform is calculated. Here, the vibration of the internal combustion engine increases as the load increases or increases as the rotational speed increases due to the mechanical vibration of the internal combustion engine itself, regardless of whether knocking occurs or not. Therefore, the first value increases as the load on the internal combustion engine increases. The first value is larger as the rotational speed is higher. The third value is calculated by correcting the value calculated based on the first value and the value relating to the deviation with the second value. For example, the third value is calculated by dividing the product of the first value and the value related to the deviation by the second value. The second value is set so as to satisfy at least one of a first condition that increases as the load of the internal combustion engine increases and a second condition that increases as the rotational speed of the internal combustion engine increases. Thereby, the 3rd value by which the change according to the load and rotation speed of an internal-combustion engine was controlled can be obtained. By comparing the third value with the fourth value, it is determined whether or not knocking has occurred. Thereby, the value by which the change according to the load and rotation speed of an internal combustion engine, such as a constant, was suppressed can be used for the 4th value used as a threshold value of knocking determination. Therefore, even during a transition in which the load of the internal combustion engine changes, a change in the threshold value for knocking determination is suppressed, and it can be determined whether knocking has occurred with high accuracy. As a result, it is possible to provide a knock determination device that can accurately determine whether or not knocking has occurred.

  In the knock determination device for an internal combustion engine according to the second aspect of the invention, in addition to the configuration of the first aspect, the second value increases as the load on the internal combustion engine increases, and the rotational speed of the internal combustion engine. Is a value that is set so as to satisfy at least one of the second conditions that the higher the value is.

  According to the second invention, for example, the first condition that the product of the first value and the value related to the deviation increases as the load of the internal combustion engine increases and the second condition that the product increases as the rotational speed of the internal combustion engine increases. A third value is calculated by dividing by a second value set to satisfy at least one of the conditions. Thereby, the 3rd value by which the change according to the load and rotation speed of an internal-combustion engine was controlled can be obtained. By comparing the third value with the fourth value, it is determined whether or not knocking has occurred. Thereby, the value by which the change according to the load and rotation speed of an internal combustion engine, such as a constant, was suppressed can be used for the 4th value used as a threshold value of knocking determination. Therefore, even during a transition in which the load of the internal combustion engine changes, a change in the threshold value for knocking determination is suppressed, and it can be determined whether knocking has occurred with high accuracy.

  In the internal combustion engine knock determination device according to the third invention, in addition to the configuration of the second invention, the second value is in addition to at least one of the first condition and the second condition, Knocking with a predetermined strength has occurred in at least one of a state where the load of the internal combustion engine is larger than a predetermined load and a state where the rotational speed of the internal combustion engine is higher than the predetermined rotational speed In this case, the value is set so as to satisfy the third condition that the third value is smaller than the fourth value.

  According to the third invention, when the load is large or the rotational speed is high, noise due to mechanical vibration of the internal combustion engine is large. Therefore, even if knocking occurs, there is little discomfort or the like that an abnormal noise due to knocking gives to the occupant. Therefore, the third value is set to be smaller than the fourth value when knocking with a predetermined strength occurs when the load is large or the rotational speed is high. Thereby, when the load is large or the rotational speed is high, it can be determined that knocking has not occurred even if knocking with a predetermined strength has occurred. For this reason, for example, it is possible to suppress the retard control of the ignition timing that is executed when it is determined that knocking has occurred, thereby suppressing a decrease in the output of the internal combustion engine.

  In the knock determination device for an internal combustion engine according to the fourth invention, in addition to the configuration of any one of the first to third inventions, the calculation means calculates the product of the value relating to the deviation and the first value as the second value. Means for dividing to calculate a third value;

  According to the fourth aspect of the invention, the third value is calculated by dividing the product of the first value and the value related to the deviation by the second value. For example, the second value is set so as to satisfy at least one of a first condition that the larger the load of the internal combustion engine is, and a second condition that the second condition is that the larger is the higher the rotational speed of the internal combustion engine. Is done. Thereby, the 3rd value by which the change according to the load and rotation speed of an internal-combustion engine was controlled can be obtained. By comparing the third value with the fourth value, it is determined whether or not knocking has occurred. Thereby, the value by which the change according to the load and rotation speed of an internal combustion engine, such as a constant, was suppressed can be used for the 4th value used as a threshold value of knocking determination. Therefore, even during a transition in which the load of the internal combustion engine changes, a change in the threshold value for knocking determination is suppressed, and it can be determined whether knocking has occurred with high accuracy.

  In the knocking determination device for an internal combustion engine according to the fifth aspect of the invention, in addition to the configuration of any one of the first to fourth aspects, the determination means determines whether the internal combustion engine has a third value greater than the fourth value. Means for determining that knocking has occurred.

  According to the fifth aspect, it is possible to detect that knocking has occurred by comparing the third value and the fourth value.

  An internal combustion engine knock determination device according to a sixth aspect of the invention is for detecting a fifth value relating to the vibration intensity of the internal combustion engine in a predetermined operating state, in addition to the configuration of any one of the first to fifth aspects. , Means for storing in advance a sixth value relating to the intensity of vibration of the internal combustion engine in a predetermined operating state, and correcting the first value based on the fifth value and the sixth value Means for further comprising.

  According to the sixth invention, for example, based on the difference between the fifth value detected in the idling state or the cranking state and the sixth value stored as the value related to the vibration intensity in the idling state or the cranking state, The first value is corrected. Further, the fifth value detected in the operating state where the temperature of the internal combustion engine is a temperature within a predetermined range and the intensity of vibration in the operating state where the temperature of the internal combustion engine is a temperature within the predetermined range. The first value is corrected based on the difference from the sixth value stored as the value. Thereby, the dispersion | variation by the individual difference of the knock sensor contained in the detected 1st value can be suppressed.

  In the knock determination device for the internal combustion engine according to the seventh aspect of the invention, in addition to the configuration of the sixth aspect, the predetermined operating state is an idling state.

  According to the seventh aspect, the first value can be corrected based on the vibration of the internal combustion engine in the idling state in which the vibration of the internal combustion engine is relatively stable. Thereby, the first value can be corrected with high accuracy.

  In the internal combustion engine knock determination device according to the eighth aspect of the invention, in addition to the configuration of the sixth aspect, the predetermined operating state is a cranking state.

  According to the eighth invention, the first value can be corrected based on the vibration of the internal combustion engine in the cranking state in which the vibration of the internal combustion engine is relatively stable. Thereby, the first value can be corrected with high accuracy.

  In the knock determination device for an internal combustion engine according to the ninth aspect of the invention, in addition to the configuration of the sixth aspect of the invention, the predetermined operation state is an operation state in which the temperature of the internal combustion engine is a temperature within a predetermined range. It is.

  According to the ninth aspect, the first value is corrected based on the fifth value and the sixth value in the operating state that the temperature of the internal combustion engine is a temperature within a predetermined range. Thereby, it is possible to suppress the difference between the fifth value and the sixth value caused by the difference in the output of the knock sensor due to the different temperature conditions. Therefore, the first value can be corrected with high accuracy.

  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 crank position sensor 306 increases and decreases, and an electromotive force is generated in the coil portion. . Crank position sensor 306 transmits a signal representing the electromotive force to engine ECU 200. Engine ECU 200 detects the crank angle based on the signal transmitted from crank position sensor 306.

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

  Engine ECU 200 performs arithmetic processing based on 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.

  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. The knock waveform model is a combined wave of vibrations in each frequency band. Note that CA in FIG. 2 indicates a crank angle.

  The knock waveform model in the present embodiment corresponds to vibrations after the peak value of the vibration intensity generated by knocking. In addition, as shown in FIG. 3, you may memorize | store the knock waveform model corresponding to the vibration after the rise of the vibration resulting from knocking.

  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.

  The knock waveform model is created using the engine 100 (hereinafter referred to as a characteristic center engine) in which the dimensions of the engine 100 and the output value of the knock sensor 300 are the median of the tolerances of the dimensions and the output value of the knock sensor 300 Is done. That is, the knock waveform model is a vibration waveform when knocking is forcibly generated in the characteristic center engine.

  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 addition to the knock waveform model, the memory 202 stores the intensity of vibration when the characteristic center engine is operated in an idling state, as shown in FIG. 4, for each frequency band of vibration. The vibration intensity of the characteristic central engine in the idling state is a value obtained by integrating the output voltage value of the knock sensor 300 (a value indicating the vibration intensity) at the knock detection gate (90 degrees from the top dead center) (hereinafter referred to as an integrated value). ). The intensity of vibration may be represented by a value corresponding to the output voltage value of knock sensor 300. In the present embodiment, the vibration intensities (integrated values) in the four frequency bands from the first frequency band to the fourth frequency band are stored, but the number of frequency bands is not limited to four. .

  In the present embodiment, as will be described later, the integrated value of vibration detected in an operation state (for example, during acceleration) different from the idling state is corrected using the integrated value of vibration of the characteristic central engine in the idling state. .

  Further, as shown in FIG. 5, in the memory 202, BGL (Back Ground Level), which is a value representing the vibration intensity of the engine 100 in a state where the engine 100 is not knocked, is set as the engine speed. Correspondingly stored.

  The higher the rotational speed of the engine 100, the greater the mechanical vibration strength of the engine 100 itself. Therefore, as shown in FIG. 5, BGL is stored as a value that increases as the engine speed increases.

  Whether or not knocking has occurred is determined by whether or not the knock intensity N calculated using BGL is larger than the determination value indicated by the broken line in FIG. When knock magnitude N is larger than the determination value, it is determined that knocking has occurred. When knock magnitude N is smaller than the determination value, it is determined that knocking has not occurred. A method for calculating knock magnitude N will be described in detail later.

  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 determines whether or not an integrated value from the top dead center in the idling state to 90 degrees has been calculated. Since the engine ECU 200 determines the operating state of the engine 100 and the integrated value is calculated by the engine ECU 200, whether or not the integrated value in the idling state is calculated is determined inside the engine ECU 200. If the integrated value in the idling state has been calculated (YES in S102), the process proceeds to S104. If not (NO in S102), the process proceeds to S100.

  In S104, engine ECU 200 calculates a correction coefficient for vibration intensity (integrated value) for each frequency band. The correction coefficient is calculated, for example, by dividing the vibration intensity (integrated value) of the characteristic center engine stored in the memory 202 in the idling state by the integrated value actually calculated in the idling state. The correction coefficient calculation method is not limited to this.

  In S106, engine ECU 200 calculates an integrated value for vibration in the first frequency band in an operating state different from the idling state. In S106, the integrated value is calculated by integrating the output voltage value of knock sensor 300 (a value representing the intensity of vibration) every 5 degrees (for 5 degrees) in crank angle.

  In S108, engine ECU 200 calculates an integrated value for vibration in the second frequency band in an operating state different from the idling state. In S108, the integrated value is calculated by integrating the output voltage value of knock sensor 300 (a value representing the intensity of vibration) every 5 degrees (for 5 degrees) in crank angle.

  In S110, engine ECU 200 calculates an integrated value for the vibration in the third frequency band in an operating state different from the idling state. In S110, the integrated value is calculated by integrating the output voltage value of knock sensor 300 (a value representing the intensity of vibration) every 5 degrees (for 5 degrees) in crank angle.

  In S112, engine ECU 200 calculates an integrated value for the vibration in the fourth frequency band in an operating state different from the idling state. In S112, the integrated value is calculated by integrating the output voltage value of knock sensor 300 (a value representing the intensity of vibration) every 5 degrees (for 5 degrees) in crank angle. Note that the processes of S106 to S112 may be performed simultaneously.

  In S114, engine ECU 200 corrects the integrated value of vibration in each frequency band (integrated value every 5 degrees). The integrated value is corrected by multiplying the integrated value of each frequency band by the correction coefficient of that frequency band. The method for correcting the integrated value is not limited to this.

  In S116, engine ECU 200 synthesizes the integrated value of the vibration in each frequency band after correction. Thereby, a vibration waveform from the top dead center to 90 degrees is detected in the combustion stroke. In S118, engine ECU 200 normalizes the detected vibration waveform. Here, the normalization of the vibration waveform is, for example, by dividing each integrated value by the maximum value of the integrated value in the detected vibration waveform, thereby reducing the vibration intensity from 0 to 1 as shown in FIG. It is expressed in numbers.

  Returning to FIG. 7, in S120, engine ECU 200 calculates correlation coefficient K, which is a value related to the deviation between the normalized vibration waveform and the 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) for each crank angle (every 5 degrees), the correlation coefficient K is calculated.

  The absolute value of the deviation between the normalized vibration waveform and knock waveform model for each crank angle is ΔS (I) (I is a natural number), and the value obtained by integrating the vibration intensity in the knock waveform model with the crank angle (knock waveform model) If S is the area, the correlation coefficient K is calculated by the equation K = (S−ΣΔS (I)) / S. Here, ΣΔS (I) is the total sum of ΔS (I) from the top dead center to 90 degrees. Note that the method of calculating the correlation coefficient K is not limited to this.

  In S122, engine ECU 200 calculates knock magnitude N. When the maximum value of the integrated value after correction is P, the knock magnitude N is calculated by the equation N = P × K / BGL. The method for calculating knock magnitude N is not limited to this.

  Here, BGL is knock strength even when knocking of a predetermined strength (for example, small strength) occurs when the condition that the rotational speed of engine 100 is higher than the predetermined rotational speed is satisfied. N is set to be smaller than a predetermined determination value.

  In S124, 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 S124), the process proceeds to S126. If not (NO in S124), the process proceeds to S130.

  In S126, engine ECU 200 determines that knocking has occurred in engine 100. In S128, engine ECU 200 retards the ignition timing. In S130, engine ECU 200 determines that knocking has not occurred in engine 100. In S132, engine ECU 200 advances the ignition timing.

  The operation of engine ECU 200 of the knock 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).

  As shown by a solid line in FIG. 9, when the integrated value of vibration from the top dead center to 90 degrees in the idling state is calculated (YES in S102), the integrated value of the vibration of the characteristic central engine in the idling state (FIG. 9). The correction coefficient is calculated by dividing the broken line in FIG. 5 for each frequency band by the integrated value in the detected vibration waveform (S104).

  Further, an integrated value every 5 degrees is calculated for vibrations in the first frequency band in an operating state different from the idling state (S106). Thereby, as shown in FIG. 10, the vibration waveform of the first frequency band is detected.

  Further, an integrated value every 5 degrees is calculated for vibrations in the second frequency band in an operating state different from the idling state (S108). Thereby, as shown in FIG. 11, the vibration waveform of the second frequency band is detected.

  Further, an integrated value every 5 degrees is calculated for vibrations in the third frequency band in an operating state different from the idling state (S110). Thereby, as shown in FIG. 12, the vibration waveform of the third frequency band is detected.

  Furthermore, an integrated value is calculated every 5 degrees for vibrations in the fourth frequency band in an operating state different from the idling state (S112). Thereby, as shown in FIG. 13, the vibration waveform of the fourth frequency band is detected.

  The calculated integrated value every 5 degrees is multiplied by the correction coefficient of the corresponding frequency band, and the integrated value of each frequency band is corrected (S114). In the idling state, when the calculated integrated value is larger than the stored integrated value (the integrated value of the vibration of the characteristic central engine), the integrated value every 5 degrees in the operating state different from the idling state is reduced. On the other hand, when the calculated integrated value is smaller than the stored integrated value (the integrated value of the vibration of the characteristic center engine) in the idling state, the integrated value every 5 degrees in the driving state different from the idling state is increased. The Thereby, variation in the intensity of vibration caused by individual differences of knock sensors 300 can be suppressed.

  The corrected integrated values of the vibrations in the respective frequency bands are synthesized (S116), and a vibration waveform from the top dead center to 90 degrees is detected in the combustion stroke as shown in FIG. 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. Therefore, the comparison between the detected vibration waveform and the knock waveform model can be facilitated.

  The vibration waveform is normalized using the maximum integrated value in the vibration waveform thus detected (S118). Here, it is assumed that normalization is performed using integrated values from 15 degrees to 20 degrees.

  In normalization, the integrated value at each crank angle is divided by the integrated value from 15 degrees to 20 degrees, and the vibration intensity in the vibration waveform is represented by a dimensionless number from 0 to 1, as shown in FIG. By this normalization, it is possible to compare the detected vibration waveform with the knock waveform model regardless of the vibration intensity. 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.

  As shown in FIG. 15, the timing at which the vibration intensity is maximized in the vibration waveform after normalization is matched with the timing at which the vibration intensity is maximized in the knock waveform model. And the absolute value ΔS (I) of the deviation for each crank angle between the knock waveform model and the knock waveform model. The correlation coefficient K is calculated by K = (S−ΣΔS (I)) / S based on the sum ΣΔS (I) of ΔS (I) and the value S obtained by integrating the vibration intensity with the crank angle in the knock waveform model. (S120). Thereby, the degree of coincidence between the detected vibration waveform and the knock waveform model can be expressed numerically and objectively determined.

  Further, the knock magnitude N is calculated by dividing the product of the calculated correlation coefficient K and the corrected maximum value P by BGL (S122). 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, the maximum value P of the integrated values used when calculating the knock magnitude N is calculated by integrating the output voltage value of the knock sensor 300. The output voltage value of knock sensor 300 increases as the rotational speed of engine 100 increases, and the intensity of mechanical vibration of engine 100 itself increases. Therefore, the maximum integrated value P increases as the rotational speed of engine 100 increases.

  By dividing the product of the maximum value P of the integrated value and the correlation coefficient K by BGL stored as a value that increases as the engine speed increases, as shown by a solid line in FIG. It is possible to suppress the calculated knock magnitude N from changing according to the rotational speed of engine 100.

  Thereby, as indicated by a broken line in FIG. 16, it is possible to determine whether or not knocking has occurred using a constant determination value in which a change according to the rotational speed of engine 100 is suppressed. Therefore, even during a transition in which the rotational speed of engine 100 changes, the change in the determination value is suppressed, and it can be determined whether knocking has occurred with high accuracy. In FIG. 16, the determination value is described as a constant, but the determination value may be gradually changed according to the engine speed.

  If knock magnitude N is greater than a predetermined determination value (YES in S124), it is determined that knocking has occurred (S126), and the ignition timing is retarded (S128). Thereby, occurrence of knocking is suppressed.

  On the other hand, when knock intensity N is not greater than a predetermined determination value (NO in S124), it is determined that knocking has not occurred (S130), and the ignition timing is advanced (S132).

  Here, BGL is knock strength even when knocking of a predetermined strength (for example, small strength) occurs when the condition that the rotational speed of engine 100 is higher than the predetermined rotational speed is satisfied. N is set to be smaller than a predetermined determination value. Therefore, in a region where the rotational speed of engine 100 is higher than a predetermined rotational speed, it is determined that knocking has not occurred even when knocking with low strength has occurred (S130), and ignition is performed. The timing is advanced (S132).

  Thereby, in the high speed region, the output of engine 100 can be prioritized over the suppression of knocking. In this case, knocking is not suppressed, but in a high rotation region, since the sound is loud from a sound source other than knocking such as traveling sound, the discomfort given to the occupant by the abnormal sound due to knocking is small.

  As described above, the engine ECU of the knock determination device according to the present embodiment calculates the integrated value (first value) of the output voltage value of the knock sensor for each frequency band of vibration. Further, the correction coefficient is calculated by comparing the integrated value (fifth value) calculated in the idling state with the integrated value (sixth value) of the characteristic central engine stored in advance. With this correction coefficient, the integrated value (first value) calculated in the driving state different from the idling state is corrected. Thereby, variation in the intensity of vibration due to individual differences among engines can be suppressed. By synthesizing the calculated value after correction (first value), the vibration waveform of the engine in an operating state different from the idling state is detected. This vibration waveform and the knock waveform model are compared, and a correlation coefficient K is calculated. BGL (second value) stored as a value such that the product of the calculated correlation coefficient K and the corrected maximum value P (first value) increases as the engine speed increases. The knock magnitude N (third value) is calculated by dividing by. When knock magnitude N is larger than a determination value (fourth value), it is determined that knocking has occurred in the engine. When knock magnitude N is not greater than the determination value, it is determined that knocking has not occurred in the engine. Here, the maximum value P (first value) of the integrated values used when calculating the knock intensity N is calculated by integrating the output voltage value of the knock sensor. The output voltage value of the knock sensor becomes higher as the engine speed of the engine itself becomes higher as the engine speed increases. Therefore, the maximum value P (first value) of the integrated values increases as the engine speed increases. By dividing the product of the maximum value P (first value) of the integrated value and the correlation coefficient K by BGL (second value), the calculated knock magnitude N (third value) is obtained. It can suppress changing according to the number of rotations of an engine. Thereby, it can be determined whether knocking has occurred using the determination value (fourth value) in which the change according to the engine speed is suppressed. Therefore, even when the engine speed changes, the change in the determination value (fourth value) is suppressed, and it can be determined whether knocking has occurred with high accuracy.

  In this embodiment, the correction coefficient is calculated based on the integrated value in the idling state. However, instead of the integrated value in the idling state, the integrated value in the cranking state (when the engine is started by a starter motor or the like). The correction coefficient may be calculated as follows. In this case, you may make it correct | amend the integrated value in the driving | running state different from a cranking state.

  Further, since the output of knock sensor 300 changes under the influence of temperature, it is based on the integrated value when the temperature of engine 100, that is, the temperature of the cooling water of engine 100 is within a predetermined temperature range. Thus, the correction coefficient may be calculated.

  In this case, the integrated value stored as the integrated value in the idling state or the cranking state when the temperature of the cooling water is within the predetermined temperature range is the same as the temperature of the cooling water within the predetermined temperature range. In this case, the correction coefficient may be calculated by dividing by the integrated value actually calculated in the idling state or the cranking state.

  Further, the greater the load on engine 100, the greater the mechanical vibration strength of engine 100 itself. Therefore, BGL may be stored as a value that increases as the load on engine 100 increases. In this case, when the condition that the load of engine 100 is larger than a predetermined load is satisfied, knock strength N is determined in advance even when knocking of a predetermined strength (for example, a small strength) occurs. BGL may be set to be smaller than the determined value.

  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 (the 1) which shows the knock waveform model memorize | stored in the memory of engine ECU. It is a figure (the 2) which shows the knock waveform model memorize | stored in the memory of engine ECU. It is a figure which shows the integrated value of the output voltage value of the knock sensor of the characteristic center engine in an idling state. It is a figure which shows BGL. It is a figure which shows a judgment value. It is a flowchart which shows the control structure of the program which engine ECU of the knock determination apparatus which concerns on embodiment of this invention performs. It is a figure which shows the vibration waveform after normalization. It is a figure which shows the integrated value of the output voltage value of a knock sensor in an idling state. It is a figure which shows the waveform of the vibration of a 1st frequency band. It is a figure which shows the waveform of the vibration of a 2nd frequency band. It is a figure which shows the waveform of the vibration of a 3rd frequency band. It is a figure which shows the waveform of the vibration of a 4th frequency band. It is a figure which shows the vibration waveform before normalization. It is a figure which shows the state which compared the vibration waveform after normalization, and a knock waveform model. It is a figure which shows knock intensity | strength N and a determination value.

Explanation of symbols

  100 engine, 104 injector, 106 spark plug, 110 crankshaft, 200 engine ECU, 300 knock sensor, 302 water temperature sensor, 304 timing rotor, 306 crank position sensor, 308 throttle opening sensor.

Claims (9)

Intensity detecting means for detecting a first value relating to the intensity of vibration of the 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 at a predetermined interval for a crank angle based on the first value;
Means for storing in advance the vibration waveform of the internal combustion engine;
Means for calculating a value relating to a deviation between the detected waveform and the stored waveform based on a result of comparing the detected waveform with the stored waveform;
A calculating means for correcting a value relating to the deviation and a value calculated based on the first value with a second value to calculate a third value relating to the intensity of vibration of the internal combustion engine;
Means for previously storing a fourth value relating to the intensity of vibration of the internal combustion engine;
An internal combustion engine knock determination device comprising: determination means for determining whether knock has occurred in the internal combustion engine based on a result of comparison between the third value and the fourth value.   The second value satisfies at least one of a first condition that the larger the load of the internal combustion engine becomes, and a second condition that the second value becomes larger as the rotational speed of the internal combustion engine becomes higher. The knock determination device for an internal combustion engine according to claim 1, which is a set value.   In addition to at least one of the first condition and the second condition, the second value is determined when the load of the internal combustion engine is greater than a predetermined load and the rotation of the internal combustion engine. The third value is smaller than the fourth value when knocking of a predetermined strength occurs in at least one of the states where the number is higher than the predetermined number of revolutions. The knock determination device for an internal combustion engine according to claim 2, wherein the knocking determination device is a value set so as to satisfy the third condition.   The calculation means includes means for calculating the third value by dividing a product of the value related to the deviation and the first value by the second value. An internal combustion engine knock determination device according to claim 1.   The internal combustion engine according to any one of claims 1 to 4, wherein the determination means includes means for determining that knocking has occurred in the internal combustion engine when the third value is greater than the fourth value. Engine knocking determination device. The knocking determination device includes:
Means for detecting a fifth value relating to the intensity of vibration of the internal combustion engine in a predetermined operating state;
Means for storing in advance a sixth value relating to the intensity of vibration of the internal combustion engine in the predetermined operating state;
The knock determination device for an internal combustion engine according to any one of claims 1 to 5, further comprising means for correcting the first value based on the fifth value and the sixth value.   The knock determination device for an internal combustion engine according to claim 6, wherein the predetermined operating state is an idling state.   The knock determination device for an internal combustion engine according to claim 6, wherein the predetermined operating state is a cranking state.   The knock determination device for an internal combustion engine according to claim 6, wherein the predetermined operating state is an operating state in which a temperature of the internal combustion engine is a temperature within a predetermined range.

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