JP4557893B2 - Ignition timing control device for internal combustion engine - Google Patents

Description

  The present invention relates to an ignition timing control device for an internal combustion engine, and more particularly to a technique for controlling the ignition timing according to the presence or absence of knocking.

  Conventionally, various methods for determining the presence or absence of knocking (knocking) have been proposed. For example, there is a technique for determining the occurrence of knocking based on whether or not the intensity of vibration detected from an internal combustion engine is greater than a knock determination value. A knock control device for an internal combustion engine described in Japanese Patent Laying-Open No. 2003-21032 (Patent Document 1) includes a knock sensor for detecting knocking of the internal combustion engine, and statistical processing for statistically processing an output signal detected by the knock sensor. A first temporary determination unit that determines the occurrence of knocking based on the processing result of the statistical processing unit, and a second temporary determination unit that determines the occurrence of knocking based on the waveform shape of the output signal detected by the knock sensor A determination unit, and a final knock determination unit that finally determines the occurrence of knocking based on the results of the knock temporary determination by the first temporary determination unit and the knock temporary determination by the second temporary determination unit. The final knock determination unit determines that knocking has finally occurred when both the first temporary determination unit and the second temporary determination unit determine that knocking has occurred. The first provisional determination unit compares the maximum value of the output signal detected by the knock sensor with the knock determination level (knock determination value) calculated based on the processing result of the statistical processing unit, thereby preventing knocking. It is determined whether it has occurred. The knock determination value is corrected to a value obtained by subtracting the set value ΔV from the knock determination value, or a value obtained by adding the product of the value A and the set value ΔV greater than “1” to the knock determination value, based on the occurrence frequency of knocking. Is done.

According to the knock control device described in this publication, only when it is determined that knocking has occurred in each temporary determination using the knock temporary determination by the statistical processing program and the knock temporary determination by the waveform shape program, Finally, it is determined that knocking has occurred. Thereby, in the knock determination using only the statistical processing program and the waveform shape program, it is possible to accurately determine the occurrence of knocking even for an output signal in which knocking is erroneously detected.
JP 200321032 A

  However, the knock control device described in Japanese Patent Laid-Open No. 2003-21032 only discloses the correction of the knock determination level during operation of the internal combustion engine, and the corrected knock determination after the internal combustion engine is stopped. There is no disclosure or suggestion on how to use the level during the next run. Therefore, the knock determination level is corrected again after the operation of the internal combustion engine is resumed, and the knock determination value is set so that the ignition timing can be appropriately controlled by accurately determining whether or not knocking has occurred. It takes time. Therefore, there is a possibility that the ignition delay when knocking occurs or the ignition advance when knocking does not occur cannot be performed properly.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an ignition timing control device for an internal combustion engine that can appropriately control the ignition timing.

  An ignition timing control device for an internal combustion engine according to a first aspect of the present invention includes a knock strength calculation means for calculating a knock strength related to the strength of vibration caused by knocking based on the strength of vibration generated in the internal combustion engine, and the knock strength And a control means for controlling the ignition timing of the internal combustion engine based on a result of comparing the predetermined determination value with a predetermined determination value, a correction means for correcting the determination value based on the occurrence frequency of knocking, and a correction Storage means for storing the determined determination value, and setting means for setting an initial value of the determination value based on the stored determination value.

  According to the first aspect, the knock magnitude related to the magnitude of the vibration caused by the knocking is calculated based on the magnitude of the vibration generated in the internal combustion engine. The ignition timing of the internal combustion engine is controlled based on a result of comparing the knock magnitude with a predetermined determination value. For example, if the knock intensity is greater than a predetermined determination value, it is determined that knocking has occurred, and the ignition timing is retarded. When the knock intensity is smaller than a predetermined determination value, it is determined that knocking has not occurred, and the ignition timing is advanced. By the way, even if the same vibration occurs in the internal combustion engine due to, for example, variation or deterioration of the output value of the knock sensor, the intensity detected by the knock sensor may change, and the calculated knock intensity may change. In this case, the ignition timing appropriately controlled in the initial state of the internal combustion engine may be inappropriate. Therefore, for example, when it can be said that the frequency of occurrence of knocking is high, it is necessary to correct the determination value in accordance with the state of vibration generated in the internal combustion engine so that the frequency of ignition timing retard control is increased. . Therefore, the determination value is corrected based on the occurrence frequency of knocking. For example, when the occurrence frequency of knocking is higher than a predetermined frequency, the determination value is corrected to be small. Therefore, the ignition timing retarding control can be performed more. On the contrary, when the occurrence frequency of knocking is lower than a predetermined frequency, the determination value is corrected so as to increase. Therefore, more advance control of the ignition timing can be performed. Thereby, the determination value can be corrected based on the occurrence frequency of knocking, and the ignition timing can be controlled appropriately. In this way, the determination value corrected so that the ignition timing can be appropriately controlled is stored, and the initial value of the determination value at the next operation, for example, is set based on the stored determination value. Thus, the determination value corrected based on the occurrence frequency of knocking can be used from the start of the next operation. Therefore, it is possible to appropriately control the ignition timing without waiting for correction of the determination value. As a result, an ignition timing control device for an internal combustion engine that can appropriately control the ignition timing can be provided.

  In the ignition timing control apparatus for an internal combustion engine according to the second invention, in addition to the configuration of the first invention, the setting means includes means for setting an initial value smaller than the stored determination value.

  According to the second invention, an initial value smaller than the stored determination value is set. Thereby, for example, in an internal combustion engine in which the ignition timing is retarded when the knock magnitude is greater than a predetermined determination value, it is possible to easily retard the ignition timing. Therefore, it is possible to easily suppress the occurrence of knocking.

  In the ignition timing control device for an internal combustion engine according to the third invention, in addition to the configuration of the first or second invention, the correction means increases the determination value when the occurrence frequency of knocking is low compared to when it is high. Means for correcting the determination value and means for correcting the determination value a plurality of times. The ignition timing control device includes means for increasing the correction amount of the determination value when the correction for increasing the determination value is continuously performed a predetermined number of times or more.

  According to the third aspect of the invention, when the occurrence frequency of knocking is low, the determination value is corrected to be larger than when it is high. When correction for increasing the determination value is continuously performed for a predetermined number of times or more, the correction amount of the determination value is increased. Thereby, for example, in the internal combustion engine in which the determination value is increased when the occurrence frequency of knocking is low, the determination value can be quickly increased when the occurrence frequency of knocking is low. Therefore, for example, in an internal combustion engine in which the ignition timing is retarded when the knock intensity is greater than a predetermined determination value, the ignition timing is retarded more than necessary even though the occurrence frequency of knocking is low. Can be suppressed. As a result, the ignition timing can be controlled appropriately.

  According to a fourth aspect of the invention, there is provided an internal combustion engine ignition timing control apparatus that, in addition to the configuration of any one of the first to third aspects, knocks occur every cycle based on a result of comparing a judgment value with a knock intensity. It further includes a determination means for determining whether or not it has been performed. The control means includes means for controlling the ignition timing of the internal combustion engine based on the determination result by the determination means.

  According to the fourth aspect of the invention, in the internal combustion engine in which it is determined whether or not knocking has occurred every cycle based on the result of comparing the determination value and the knock magnitude, and the ignition timing is appropriately set in the internal combustion engine in which the ignition timing is controlled. Can be controlled.

  In the ignition timing control device for an internal combustion engine according to the fifth invention, in addition to the configuration of any one of the first to fourth inventions, the correction means corrects the determination value every predetermined number of cycles. Including means.

  According to the fifth aspect of the invention, the determination value is corrected every predetermined number of cycles. Thereby, the determination value can be updated repeatedly. Therefore, a determination value corresponding to the occurrence frequency of knocking in a state closer to the current operating state can be obtained.

  In the ignition timing control device for an internal combustion engine according to the sixth invention, in addition to the configuration of any one of the first to fifth inventions, the storage means is an SRAM.

  According to the sixth invention, the corrected determination value is stored in an SRAM (Static Random Access Memory). Thus, for example, the determination value can be continuously stored even after the internal combustion engine is stopped unless the power supplied to the SRAM is interrupted by replacing the auxiliary battery or the like.

  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, an engine 100 for a vehicle equipped with an ignition timing control apparatus according to a first embodiment of the present invention will be described. The ignition timing control apparatus 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. The ignition timing is controlled to be MBT (Minimum advance for Best Torque) that maximizes the output torque, but is retarded or advanced according to the operating state of the engine 100 such as when knocking occurs. Or

  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. The engine ECU 200 includes a knock sensor 300, a water temperature sensor 302, a crank position sensor 306 provided facing the timing rotor 304, a throttle opening sensor 308, a vehicle speed sensor 310, an ignition switch 312, and an air flow meter. 314 is connected.

  Knock sensor 300 is provided in a cylinder block of engine 100. 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 and the rotational speed of crankshaft 110 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. Air flow meter 314 detects the amount of air taken into engine 100 and transmits a signal representing the detection result to engine ECU 200.

  Engine ECU 200 is operated by electric power supplied from auxiliary battery 320 as a power source. Engine ECU 200 performs arithmetic processing based on signals transmitted from each sensor and ignition switch 312, a map and a program stored in ROM (Read Only Memory) 202 and SRAM 204, and engine 100 enters a desired operating state. And control the equipment.

  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. The frequency of vibration generated due to knocking is not constant and has a predetermined bandwidth. Therefore, in the present embodiment, vibrations included in the first frequency band A, the second frequency band B, and the third frequency band C are detected as shown in FIG. Note that CA in FIG. 2 indicates a crank angle. Note that the frequency band of vibrations generated due to knocking is not limited to three.

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

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

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

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

  The integrating unit 450 integrates the signals selected by the bandpass filter (1) 410 to the bandpass filter (3) 430, that is, the vibration intensity by 5 degrees in terms of crank angle. Hereinafter, the integrated value is referred to as an integrated value. The integrated value is calculated for each frequency band. By calculating the integrated value, a vibration waveform in each frequency band is detected.

  Further, the calculated integrated values of the first frequency band A to the third frequency band C are added corresponding to the crank angle. That is, the vibration waveforms in the first frequency band A to the third frequency band C are synthesized.

  Thereby, as shown in FIG. 4, the vibration waveform of engine 100 is detected. That is, the combined waveform of first frequency band A to third frequency band C is used as the vibration waveform of engine 100.

  The detected vibration waveform is compared with a knock waveform model stored in ROM 202 of engine ECU 200 as shown in FIG. The knock waveform model is created in advance as a model of a vibration waveform when knocking occurs in engine 100.

  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, after the peak value of the vibration intensity, it is determined that the vibration intensity decreases as the crank angle increases. The corner is not fixed.

  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.

  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. The method of creating the knock waveform model is not limited to this, and may be created by simulation.

  In the comparison between the detected waveform and the knock waveform model, as shown in FIG. 6, the normalized waveform and the knock waveform model are compared. Here, normalization is to express the intensity of vibration by a dimensionless number from 0 to 1, for example, by dividing each integrated value by the maximum integrated value in the detected vibration waveform. The normalization method is not limited to this.

  In the present embodiment, engine ECU 200 calculates correlation coefficient K, which is a value related to the deviation between the normalized vibration waveform and 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. In the present embodiment, correlation coefficient K is calculated as a larger value as the shape of the vibration waveform is closer to the shape of the knock waveform model. Therefore, when the vibration waveform includes a vibration waveform due to a factor other than knocking, the correlation coefficient K is calculated to be small. Note that the method of calculating the correlation coefficient K is not limited to this.

  Further, engine ECU 200 calculates knock magnitude N based on the maximum value (peak value) of the integrated values. If the 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 = P / BGL. It is calculated by the equation. BGL is stored in the ROM 202. The method for calculating knock magnitude N is not limited to this.

  In the present embodiment, engine ECU 200 compares calculated knock magnitude N with determination value V (KX) stored in SRAM 204, and further compares the detected waveform with the stored knock waveform model. Whether or not knocking has occurred in engine 100 is determined for each ignition cycle.

  As shown in FIG. 7, the determination value V (KX) is stored as a map using the engine speed NE and the intake air amount KL as parameters.

  When the engine 100 or the vehicle is shipped, a value determined in advance through experiments or the like is used as the determination value V (KX) (initial value of the determination value V (KX) at the time of shipment) stored in the ROM 202. However, the detected intensity can change even when the same vibration occurs in engine 100 due to variations or deterioration in the output value of knock sensor 300. In this case, it is necessary to correct the determination value V (KX) and determine whether or not knocking has occurred using the determination value V (KX) corresponding to the actually detected intensity.

  Therefore, in the present embodiment, the relationship between the intensity value LOG (V), which is a value obtained by logarithmically converting the intensity V, and the frequency (also referred to as the number of times or probability) at which each intensity value LOG (V) is detected is shown. Based on the frequency distribution, knock determination level V (KD) is calculated.

  An intensity value LOG (V) is calculated for each region using the engine speed NE and the intake air amount KL as parameters. The intensity V used for calculating the intensity value LOG (V) is an intensity peak value (peak value of integrated value every 5 degrees) between predetermined crank angles. Based on the calculated intensity LOG (V), a median value V (50) is calculated that accumulates the frequency of the intensity value LOG (V) from the minimum value to 50%. In addition, a standard deviation σ at the intensity value LOG (V) equal to or lower than the median value V (50) is calculated. For example, in the present embodiment, median value V (50) and standard deviation σ approximated to median value and standard deviation calculated based on a plurality of (for example, 200 cycles) intensity values LOG (V) are as follows: It is calculated for each ignition cycle by the calculation method.

  When the intensity value LOG (V) detected this time is larger than the median value V (50) calculated last time, a value obtained by adding a predetermined value C (1) to the median value V (50) calculated last time Is calculated as the median value V (50) of this time. Conversely, when the intensity value LOG (V) detected this time is smaller than the median value V (50) calculated last time, a predetermined value C (2) ( For example, a value obtained by subtracting C (2) is the same value as C (1) is calculated as the median value V (50) of this time.

  The intensity value LOG (V) detected this time is smaller than the median value V (50) calculated last time, and the value obtained by subtracting the standard deviation σ calculated last time from the median value V (50) calculated last time. Is larger, the value obtained by subtracting a value obtained by doubling a predetermined value C (3) from the previously calculated standard deviation σ is calculated as the current standard deviation σ. Conversely, when the intensity value LOG (V) detected this time is larger than the median value V (50) calculated last time, or the standard deviation σ calculated last time from the median value V (50) calculated last time is used. When the value is smaller than the subtracted value, a value obtained by adding a predetermined value C (4) (for example, C (4) is the same value as C (3)) to the previously calculated standard deviation σ is the current standard deviation. Calculated as σ. In addition, the calculation method of median value V (50) and standard deviation (sigma) is not limited to this. The initial value of median value V (50) and standard deviation σ may be a preset value or “0”.

  Knock determination level V (KD) is calculated using median value V (50) and standard deviation σ. As shown in FIG. 8, the value obtained by adding the product of coefficient U (1) (U (1) is a constant, for example, U (1) = 3) and standard deviation σ to median value V (50) is knocked. The determination level is V (KD). The method for calculating knock determination level V (KD) is not limited to this. The frequency of the intensity value LOG (V) greater than the knock determination level V (KD) is determined as the frequency of occurrence of knocking, and the determination value V (KX) is corrected based on the frequency of occurrence of knocking.

  The coefficient U (1) is a coefficient obtained from data or knowledge obtained through experiments or the like. The magnitude value LOG (V) larger than the knock determination level V (KD) when U (1) = 3 substantially matches the magnitude value LOG (V) in the ignition cycle in which knocking actually occurs. A value other than “3” may be used for the coefficient U (1).

  In the frequency distribution of the intensity value LOG (V), if knocking does not occur in the engine 100, a normal distribution is obtained as shown in FIG. 9, and the maximum value V (MAX) of the intensity value LOG (V) and the knock determination level are obtained. V (KD) matches. On the other hand, when knocking occurs, the detected intensity V increases, and when a large intensity value LOG (V) is calculated, as shown in FIG. 10, the maximum value V is greater than the knock determination level V (KD). (MAX) increases.

  Further, when the frequency of occurrence of knocking increases, the maximum value V (MAX) further increases as shown in FIG. At this time, the median value V (50) and the standard deviation σ in the frequency distribution increase with the maximum value V (MAX). Therefore, knock determination level V (KD) increases.

  An intensity value LOG (V) smaller than knock determination level V (KD) is not determined to be an intensity value LOG (V) in a cycle in which knocking has occurred. Therefore, if knock determination level V (KD) increases, knocking is correspondingly increased. Even if this occurs, the frequency at which it is determined that knocking has not occurred increases.

  Therefore, in the present embodiment, as shown in FIG. 12, the intensity value LOG (V) larger than the threshold value V (1) is used by using the intensity value LOG (V) in the region surrounded by the broken line. The median value V (50) and the standard deviation σ are calculated by excluding. FIG. 12 is a diagram in which the calculated intensity value LOG (V) is plotted for each correlation coefficient K in the cycle in which the intensity value LOG (V) was obtained.

  The threshold value V (1) is the median of the frequency distribution of the intensity value LOG (V), the standard deviation and the coefficient U (2) (U (2) is a constant in the intensity value LOG (V) below the median value. For example, it is a value obtained by adding the product of U (2) = 3).

  By extracting only the intensity value LOG (V) smaller than the threshold value V (1) and calculating the median value V (50) and the standard deviation σ, the median value V (50) and the standard deviation σ are excessive. It becomes a stable value. Thereby, knock determination level V (KD) can be suppressed from becoming excessive. Therefore, even if knocking has occurred, it is possible to suppress an increase in the frequency at which it is determined that knocking has not occurred.

  The method of extracting the intensity value LOG (V) used for calculating the median value V (50) and the standard deviation σ is not limited to this. For example, among the intensity values LOG (V) smaller than the threshold value V (1), the intensity value LOG (V) calculated in the ignition cycle in which the correlation coefficient K is larger than the threshold value K (1) is used. You may make it extract.

  Referring to FIG. 13, an engine ECU 200 that is an ignition timing control apparatus according to the present embodiment determines whether or not knocking has occurred for each ignition cycle and controls an ignition timing. The control structure will be described.

  In step (hereinafter, step is abbreviated as S) 100, engine ECU 200 detects engine speed NE based on the signal transmitted from crank position sensor 306, and based on the signal transmitted from air flow meter 314. Thus, the intake air amount KL is detected.

  In S102, 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 S104, engine ECU 200 calculates a value (integrated value) obtained 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. The integrated value is calculated for each vibration in the first frequency band A to the third frequency band C. Further, the integrated values of first frequency band A to third frequency band C are added corresponding to the crank angle, and the vibration waveform of engine 100 is detected.

  In S106, engine ECU 200 calculates the largest integrated value (peak value P) among the integrated values in the combined waveform (vibration waveform of engine 100) of first frequency band A to third frequency band C.

  In S108, engine ECU 200 normalizes the vibration waveform of engine 100. Here, normalization means that the intensity of vibration is expressed by a dimensionless number from 0 to 1 by dividing each integrated value by the calculated peak value.

  In S110, engine ECU 200 calculates correlation coefficient K, which is a value related to the deviation between the normalized vibration waveform and knock waveform model. In S112, engine ECU 200 calculates knock magnitude N.

  In S114, engine ECU 200 determines whether or not correlation coefficient K is larger than a predetermined value and knock magnitude N is larger than determination value V (KX). If correlation coefficient K is greater than a predetermined value and knock magnitude N is greater than determination value V (KX) (YES in S114), the process proceeds to S116. If not (NO in S114), the process proceeds to S120.

  In S116, engine ECU 200 determines that knocking has occurred in engine 100. In S118, engine ECU 200 retards the ignition timing. In S120, engine ECU 200 determines that knocking has not occurred in engine 100. In S122, engine ECU 200 advances the ignition timing.

  Referring to FIG. 14, a control structure of a program executed by engine ECU 200, which is an ignition timing control device according to the present embodiment, to set determination value V (KX) when engine 1000 is started will be described. .

  In S200, engine ECU 200 determines whether engine 100 that has been stopped has been started or not. For example, when engine speed NE rises above a threshold value, it is determined that engine 100 has been started. If engine 100 in the stopped state is started (YES in S200), the process proceeds to S202. If not (NO in S200), the process returns to S200.

  In S202, engine ECU 200 determines whether determination value V (KX) is stored in SRAM 204 or not. If determination value V (KX) is stored in SRAM 204 (YES in S202), the process proceeds to S204. If not (NO in S202), the process proceeds to S206.

  In S204, engine ECU 200 reads determination value V (KX) stored in SRAM 204. Thereafter, this process ends. In S206, engine ECU 200 reads determination value V (KX) stored in ROM 202. Thereafter, this process ends.

  Referring to FIG. 15, a control structure of a program executed by engine ECU 200 that is the ignition timing control device according to the present embodiment to correct determination value V (KX) every predetermined number of cycles. explain.

  In S300, engine ECU 200 calculates intensity value LOG (V) from intensity V detected based on the signal transmitted from knock sensor 300. Here, the intensity V is a peak value between predetermined crank angles (peak value of integrated value every 5 degrees).

  In S302, engine ECU 200 determines whether intensity value LOG (V) is smaller than threshold value V (1) described above. If intensity value LOG (V) is smaller than threshold value V (1) described above (YES in S302), the process proceeds to S304. If not (NO in S302), the process returns to S300.

  In S304, engine ECU 200 calculates median value V (50) and standard deviation σ for extracted intensity value LOG (V). Median value V (50) and standard deviation σ may be calculated each time intensity values LOG (V) for N (N is a natural number, for example, N = 200) cycles are extracted. .

  In S306, engine ECU 200 calculates knock determination level V (KD) based on median value V (50) and standard deviation σ.

  In S308, engine ECU 200 counts the ratio of intensity value LOG (V) larger than knock determination level V (KD) in extracted intensity value LOG (V) as knock occupancy KC.

  In S310, engine ECU 200 determines whether intensity values LOG (V) for N cycles have been extracted since the last determination value V (KX) was corrected. If intensity values LOG (V) for N cycles have been extracted (YES in S310), the process proceeds to S312. If not (NO in S310), the process returns to S300.

  In S312, engine ECU 200 determines whether knock occupancy KC is larger than threshold value KC (0) or not. If knock occupancy KC is larger than threshold value KC (0) (YES in S312), the process proceeds to S314. If not (NO in S312), the process proceeds to S316.

  In S314, engine ECU 200 decreases determination value V (KX) by a predetermined correction amount. In S316, engine ECU 200 increases determination value V (KX) by a predetermined correction amount. In S318, engine ECU 200 stores determination value V (KX) in SRAM 204.

  The operation of engine ECU 200 that is the ignition timing control device according to the present embodiment based on the above-described structure and flowchart will be described.

  During operation of engine 100, engine speed NE is detected based on a signal transmitted from crank position sensor 306, and intake air amount KL is detected based on a signal transmitted from air flow meter 314. (S100). Further, based on the signal transmitted from knock sensor 300, the intensity of vibration of engine 100 is detected (S102).

  Between the top dead center and 90 degrees in the combustion stroke, an integrated value every 5 degrees is calculated for each vibration in the first frequency band A to the third frequency band C (S104). The calculated integrated values of the first frequency band A to the third frequency band C are added corresponding to the crank angle, and the vibration waveform of the engine 100 as shown in FIG. 4 is detected.

  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.

  Based on the calculated integrated value, a peak value P of the integrated value in the combined waveform (vibration waveform of engine 100) of first frequency band A to third frequency band C is calculated (S106).

  The integrated value in the vibration waveform of the engine 100 is divided by the calculated peak value P to normalize the vibration waveform (S108). 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.

  The timing at which the vibration intensity is maximized in the normalized vibration waveform and the timing at which the vibration intensity is maximized in the knock waveform model are matched (see FIG. 6). In this state, the normalized vibration waveform and knock An absolute value ΔS (I) of deviation for each crank angle from the waveform model is calculated. 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. (S110). Thereby, the degree of coincidence between the detected vibration waveform and the knock waveform model can be expressed numerically and objectively determined. Further, by comparing the vibration waveform with the knock waveform model, it is possible to analyze whether or not the vibration is during knocking from the vibration behavior such as the vibration attenuation tendency.

  Further, knock magnitude N is calculated by dividing peak value P by BGL (S112). Thereby, it is possible to analyze in more detail whether or not the vibration of engine 100 is a vibration caused by knocking based on the intensity of vibration.

  If correlation coefficient K is greater than a predetermined value and knock magnitude N is greater than determination value V (KX) (YES in S114), it is determined that knocking has occurred (S116), and the ignition timing is The angle is retarded (S118). Thereby, occurrence of knocking is suppressed. If correlation coefficient K is greater than a predetermined value and knock magnitude N is not greater than determination value V (KX) (NO in S114), it is determined that knocking has not occurred (S120). ), The ignition timing is advanced (S122). In this manner, by comparing the knock magnitude N with the determination value V (KX), it is determined whether or not knocking has occurred for each ignition cycle, and the ignition timing is retarded or advanced. .

  By the way, even if the same vibration occurs in the engine 100 due to variations or deterioration in the output value of the knock sensor 300, the detected intensity can change. In this case, it is necessary to correct the determination value V (KX) and determine whether or not knocking has occurred using the determination value V (KX) corresponding to the actually detected intensity.

  Therefore, in engine ECU 200 that is the ignition timing control device according to the present embodiment, intensity value LOG (V) is calculated (S300). If calculated intensity value LOG (V) is smaller than threshold value V (1) described above (YES in S302), median value V (50) and standard deviation σ are calculated (S304). Based on such median value V (50) and standard deviation σ, knock determination level V (KD) is calculated (S306). Therefore, it can be suppressed that knock determination level V (KD) becomes excessive. The ratio of the intensity value LOG (V) larger than the determination level V (KD) is counted as the knock occupancy KC (S308). Intensity value LOG (V) for N cycles has been extracted since the previous determination value V (KX) was corrected (YES in S310), and knock occupancy KC is greater than threshold value KC (0) ( (YES in S312), determination value V (KX) is reduced (S314) so that the frequency of ignition timing retard control (S118) is increased. If knock occupancy KC is smaller than threshold value KC (0) (NO in S312), determination value V (KX) is increased so that the frequency of ignition timing advance control (S122) is increased. (S316). Thereby, it is possible to appropriately correct the determination value V (KX) in the knocking determination for each ignition cycle, and to appropriately control the ignition timing.

  The corrected determination value V (KX) is stored in the SRAM 204 (S318). Here, the SRAM 204 is a nonvolatile memory, and continues to store the determination value V (KX) unless the power supplied to the SRAM 204 is interrupted by replacing the auxiliary battery 320 or the like.

  Therefore, when engine 100 is started again after engine 100 is stopped (YES in S200), determination value V (KX) is stored in SRAM 204 (YES in S202). (KX) is read (S204).

  Accordingly, unless the auxiliary battery 320 is replaced, the determination value V (KX) appropriately corrected in the current trip (between the start of the engine 100 and the stop) is used as the next trip start. Can be used. Therefore, the ignition timing can be appropriately controlled from the start of engine 100.

  As described above, according to the engine ECU that is the ignition timing control device according to the present embodiment, the determination value V (KX) corrected based on the occurrence frequency of knocking is stored in the SRAM. The determination value V (KX) stored in the SRAM is read from the SRAM when the engine is started on the next trip. As a result, the ignition timing can be retarded or advanced using the determination value V (KX) appropriately corrected based on the occurrence frequency of knocking from the start of the engine. Therefore, it is possible to appropriately control the ignition timing from the start of the engine.

<Second Embodiment>
Hereinafter, a second embodiment of the present invention will be described. In the first embodiment described above, the determination value V (KX) stored in the SRAM 204 during the previous operation is used as it is. In the present embodiment, however, the determination value V (KX) is more A small determination value V (KX) is set. Other structures are the same as those in the first embodiment. The function about them is the same. Therefore, detailed description thereof will not be repeated here.

  Referring to FIG. 16, a control structure of a program executed by engine ECU 200, which is the ignition timing control device according to the present embodiment, to set determination value V (KX) will be described. Note that the program described below is executed in addition to the program in the first embodiment described above.

  In S400, engine ECU 200 determines whether determination value V (KX) has been read from SRAM 204 or not. If determination value V (KX) is read from SRAM 204 (YES in S400), the process proceeds to S402. If not (NO in S400), this process ends.

  In S402, engine ECU 200 determines a constant K determined in advance from determination value V (KX) read from SRAM 204 (K is a positive number and is larger than the correction amount of determination value V (KX)). A value obtained by subtracting only this value is set as the initial value of the determination value V (KX) in the current trip (between starting and stopping the engine 100).

  In S404, engine ECU 200 determines whether determination value V (KX) has been corrected or not. If determination value V (KX) is corrected (YES in S404), the process proceeds to S410. If not (NO in S404), the process returns to S404.

  In S410, engine ECU 200 determines in advance that current determination value V (KX) is a value obtained by adding a constant K / 2 to the initial value of the current trip (determination value V (KX) read from SRAM 204). Whether or not the value obtained by subtracting only the constant K / 2).

  If current determination value V (KX) is smaller than a value obtained by adding constant K / 2 to the initial value of the current trip (YES in S410), the process proceeds to S412. If not (NO in S410), the process proceeds to S420.

  In S412, engine ECU 200 determines whether or not N (1) (N (1) is a natural number, for example, N (1) = 3) is corrected so that determination value V (KX) is increased continuously. To do. When correction is made so that determination value V (KX) increases N (1) times continuously (YES in S412), the process proceeds to S414. If not (NO in S412), the process returns to S404.

  In S414, engine ECU 200 resets the value obtained by adding constant K / 2 to the initial value of the current trip to determination value V (KX). In S416, engine ECU 200 stores determination value V (KX) in SRAM 204. Thereafter, the process proceeds to S404.

  In S420, engine ECU 200 determines whether or not current determination value V (KX) is smaller than determination value V (KX) read from SRAM 204 when engine 100 is started.

  If current determination value V (KX) is smaller than determination value V (KX) read from SRAM 204 when engine 100 is started (YES in S420), the process proceeds to S422. If not (NO in S420), this process ends.

  In S422, engine ECU 200 determines N (2) (N (2) is a natural number and N (2)> N (1), for example, N (2) = 6) times consecutively, and determination value V It is determined whether or not the correction is made so that (KX) increases. If correction is made so that determination value V (KX) increases N (2) times consecutively (YES in S422), the process proceeds to S424. If not (NO in S422), the process returns to S404.

  In S424, engine ECU 200 resets the value obtained by adding constant K to the initial value of the current trip (determination value V (KX) read from SRAM 204) to determination value V (KX). In S426, engine ECU 200 stores determination value V (KX) in SRAM 204. Thereafter, this process ends.

  An operation of engine ECU 200 that is the control device according to the present embodiment based on the structure and flowchart as described above will be described.

  When the determination value V (KX) stored in the previous trip is read (S400), the determination value V (KX) may not be a suitable value for the current trip. For example, if the temperature on the current trip is higher than the temperature on the previous trip, or if the humidity on the current trip is lower than the humidity on the previous trip, knocking is likely to occur. Nevertheless, if the determination value V (KX) is large, it can be determined that knocking has occurred and the frequency of performing the ignition delay can be reduced.

  Therefore, when determination value V (KX) is read from SRAM 204 (YES in S400), a value obtained by subtracting a predetermined constant K from determination value V (KX) read from SRAM 204 is the current value. The initial trip value is set (S402). As a result, it is possible to suppress the difficulty in retarding the ignition timing.

  However, if the current trip is not more likely to knock than the previous trip, or if knocking is less likely to occur, the ignition timing is delayed more than necessary because the determination value V (KX) is low. Can be horned.

  In such a case, it is desirable to quickly increase the determination value V (KX). Therefore, in a state where the current determination value V (KX) is smaller than a value obtained by adding the constant K / 2 to the initial value of the current trip (YES in S410), the determination value V ( KX) is corrected so as to increase (YES in S412), the value obtained by adding a constant K / 2 to the initial value of the current trip as shown at time T (1) in FIG. It is reset to (KX) (S414).

  Furthermore, determination value V (KX) is continuously N (2) times when current determination value V (KX) is smaller than determination value V (KX) read from SRAM 204 (YES in S420). When the correction is made to be larger (YES in S422), the value obtained by adding the constant K to the initial value of the current trip is re-set to the determination value V (KX) as shown at time T (2) in FIG. It is set (S424).

  Thus, when the determination value V (KX) is continuously corrected to be increased, the determination value V (KX) can be corrected to be larger than usual. That is, the correction amount can be made larger than usual. Therefore, when it can be said that the determination value V (KX) set as the initial value in this trip is smaller than the occurrence frequency of knocking, the determination value V (KX) can be quickly increased.

  As described above, according to the engine ECU that is the ignition timing control device according to the present embodiment, the value obtained by subtracting the constant K from the determination value V (KX) read from the SRAM is the initial value of the current trip. Set to As a result, it is possible to suppress the difficulty in retarding the ignition timing. When the determination value V (KX) is corrected so as to increase continuously several times, the value obtained by adding the constant K / 2 or the constant K to the initial value of the current trip is re-entered into the determination value V (KX). Is set. Thereby, when it can be said that the determination value V (KX) set as the initial value in this trip is smaller than the occurrence frequency of knocking, the determination value V (KX) can be quickly increased. Therefore, it is possible to suppress the ignition timing from being retarded more than necessary. As a result, the ignition timing can be controlled appropriately.

  In the present embodiment, the determination value V (KX) is reset when the correction for increasing the determination value V (KX) is performed N (1) times or N (2) times continuously. However, instead of resetting, the correction amount in the correction for increasing the determination value V (KX) may be increased. In this case, the correction amount may be decreased (returned to the original) as the determination value V (KX) is corrected and increased. Further, when the determination value V (KX) becomes equal to or higher than the determination value V (KX) read from the SRAM 204 at the time of starting, the correction amount may be returned to the original value.

  Furthermore, as shown in FIG. 18, when the intensity of vibration due to noise is large, the difference between the maximum integrated value at the time of knocking and the maximum integrated value due to noise is small. May be difficult to distinguish. Therefore, instead of the peak value P of the integrated value, as shown in FIG. 19, the knock intensity is calculated using a total sum of the integrated values in the vibration waveform (a value obtained by integrating all output voltage values of the knock sensor 300 in the knock detection gate). N may be calculated. That is, the knock magnitude N may be calculated by dividing the total sum of the integrated values in the vibration waveform by BGL.

  As shown in FIG. 19, since the generation period of vibration due to noise is shorter than the generation period of vibration due to knocking, the total sum of integrated values can be greatly different between knocking and noise. Therefore, by calculating the knock intensity N based on the total sum of the integrated values, the difference between the knock intensity N calculated at the time of knocking and the knock intensity N calculated by noise can be increased. Thereby, the vibration caused by knocking and the vibration caused by noise can be clearly distinguished.

  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.

1 is a schematic configuration diagram showing an engine controlled by an engine ECU that is an ignition timing control device according to a first embodiment of the present invention. It is a figure which shows the frequency band of the vibration which generate | occur | produces with an engine at the time of knocking. It is a control block diagram which shows the engine ECU of FIG. It is a figure which shows the vibration waveform of an engine. It is a figure which shows the knock waveform model memorize | stored in ROM of engine ECU. It is the figure which compared the vibration waveform and the knock waveform model. It is a figure which shows the map of the determination value V (KX) memorize | stored in ROM or SRAM of engine ECU. It is a figure (the 1) which shows frequency distribution of intensity value LOG (V). FIG. 6 is a second diagram illustrating a frequency distribution of intensity values LOG (V). FIG. 10 is a third diagram illustrating a frequency distribution of intensity values LOG (V). It is FIG. (4) which shows frequency distribution of intensity value LOG (V). It is a figure which shows intensity value LOG (V) used in order to create frequency distribution of intensity value LOG (V). It is a flowchart (the 1) which shows the control structure of the program which engine ECU which is the ignition timing control apparatus which concerns on the 1st Embodiment of this invention performs. It is a flowchart (the 2) which shows the control structure of the program which engine ECU which is the ignition timing control apparatus which concerns on the 1st Embodiment of this invention performs. It is a flowchart (the 3) which shows the control structure of the program which engine ECU which is the ignition timing control apparatus which concerns on the 1st Embodiment of this invention performs. It is a flowchart which shows the control structure of the program which engine ECU which is an ignition timing control apparatus which concerns on the 2nd Embodiment of this invention performs. It is a timing chart which shows transition of judgment value V (KX). It is the figure (the 1) which shows the integration value at the time of knocking, and the integration value by noise. It is the figure (the 2) which shows the integrated value at the time of knocking, and the integrated value by noise.

Explanation of symbols

  100 engine, 104 injector, 106 spark plug, 110 crankshaft, 116 intake valve, 118 exhaust valve, 120 pump, 200 engine ECU, 202 ROM, 204 SRAM, 300 knock sensor, 302 water temperature sensor, 304 timing rotor, 306 crank position Sensor, 308 Throttle opening sensor, 314 Air flow meter, 320 Auxiliary battery.

Claims (5)

An ignition timing control device for an internal combustion engine,
Knock intensity calculating means for calculating knock intensity related to the intensity of vibration caused by knocking based on the intensity of vibration generated in the internal combustion engine;
Control means for controlling the ignition timing of the internal combustion engine based on a result of comparing the knock intensity with a predetermined determination value;
Correction means for correcting the determination value based on the occurrence frequency of knocking;
Storage means for storing the corrected determination value;
Setting means for setting an initial value of the determination value based on the stored determination value;
It said setting means includes means for setting a small initial value than the stored decision value, the ignition timing control system for internal combustion engine. An ignition timing control device for an internal combustion engine,
Knock intensity calculating means for calculating knock intensity related to the intensity of vibration caused by knocking based on the intensity of vibration generated in the internal combustion engine;
Control means for controlling the ignition timing of the internal combustion engine based on a result of comparing the knock intensity with a predetermined determination value;
Correction means for correcting the determination value based on the occurrence frequency of knocking;
Storage means for storing the corrected determination value;
Setting means for setting an initial value of the determination value based on the stored determination value;
The correction means includes
Means for correcting the determination value to be larger compared to the case where the occurrence frequency of knocking is low compared to the case where it is high;
Means for correcting the determination value a plurality of times,
The ignition timing control device, when the correction of increasing the determination value is performed continuously over a predetermined number of times, including means for increasing the correction amount of the determination value, the ignition of the internal combustion engine Timing control device. The ignition timing control device includes:
Based on the result of comparing the determination value and the knock strength, further includes a determination means for determining whether knocking has occurred every cycle,
The ignition timing control device for an internal combustion engine according to claim 1 or 2 , wherein the control means includes means for controlling the ignition timing of the internal combustion engine based on a determination result by the determination means. The ignition timing control device for an internal combustion engine according to any one of claims 1 to 3 , wherein the correction means includes means for correcting the determination value every predetermined number of cycles. The ignition timing control device for an internal combustion engine according to any one of claims 1 to 4 , wherein the storage means is an SRAM.

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