JP2009138625A - Ignition timing control method and ignition timing control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately determine ignition timing by correcting a decision value VJ. <P>SOLUTION: An engine ECU includes an ignition timing setting part 500, an intensity detection part 602, a calculation part 610, a determination part 612, an ignition timing control part 614, and a decision value setting part 700. The ignition timing setting part 500 sets base ignition timing depending on an engine operation state. The intensity detection part 602 detects intensity of vibration. The calculation part 610 calculates knocking intensity N based on intensity of the vibration. The determination part 612 determines the occurrence of knocking if the knocking intensity N is not less than the decision value VJ. The ignition timing control part 614 retards ignition timing by predetermined quantity if the occurrence of knocking is determined. The decision value setting part 700 includes a third correction part 713. The third correction part 713 corrects the decision value VJ if difference between the base ignition timing and the corrected ignition timing is not greater than threshold ΔCA. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ignition timing control device and an ignition timing control method for an internal combustion engine, and more particularly, to a technique for controlling an ignition timing according to a result of comparing a value related to a vibration intensity of an internal combustion engine and a determination value.

  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. However, the intensity of vibration detected in the internal combustion engine can change due to aging of the internal combustion engine and the knock sensor. In addition, the intensity of vibration detected in the internal combustion engine may be different for each individual internal combustion engine. Therefore, in order to accurately determine the presence or absence of knocking, it is desirable to correct the knock determination value according to the intensity actually detected in the internal combustion engine.

  Japanese Patent Laying-Open No. 2007-198313 (Patent Document 1) discloses an ignition timing control device for an internal combustion engine that determines a determination value according to an intensity value related to the intensity of vibration generated in the internal combustion engine. An ignition timing control device described in Patent Document 1 includes a knock intensity calculation unit for calculating a knock intensity related to the intensity of vibration caused by knocking based on the intensity of vibration generated in an internal combustion engine, a knock intensity and a determination value A control unit for controlling the ignition timing of the internal combustion engine, a detection unit for detecting an intensity value related to the intensity of vibration generated in the internal combustion engine in a plurality of ignition cycles, and an intensity A determination unit for determining the occurrence frequency of knocking based on the value, and a determination unit for determining a determination value based on the occurrence frequency of knocking and the rotation speed of the internal combustion engine are included.

According to the ignition timing control device described in this publication, the knock magnitude related to the magnitude of vibration caused by knocking is calculated based on the magnitude of vibration generated in the internal combustion engine, and the knock magnitude and a predetermined determination value are calculated. Based on the comparison result, the ignition timing of the internal combustion engine is controlled. The occurrence frequency of knocking is determined based on an intensity value related to the intensity of vibration generated in the internal combustion engine. A determination value is determined based on the occurrence frequency of knocking and the rotational speed of the internal combustion engine. For example, when it is determined that the occurrence frequency of knocking is high, the determination value is determined to be small. Conversely, when it is determined that the occurrence frequency of knocking is low, the determination value is determined to be large. In addition, when the rotational speed of the internal combustion engine is low, the determination value is determined so as to be closer to a value that can appropriately control the ignition timing, compared to when the rotational speed is high. Thus, the determination value can be determined based on the occurrence frequency of knocking and the rotational speed of the internal combustion engine, and the ignition timing can be appropriately controlled. As a result, the ignition timing can be controlled appropriately.
JP 2007-198313 A

  However, in an operating state where knocking hardly occurs, the frequency of occurrence of knocking cannot be obtained correctly. Therefore, the determination value cannot be corrected according to the occurrence frequency of knocking as in the ignition timing control device described in Japanese Patent Application Laid-Open No. 2007-198313. For this reason, the determination value may be smaller than necessary. If the determination value is smaller than necessary, the ignition timing may be erroneously retarded even when a small intensity vibration due to a factor different from knocking is detected. In particular, when shifting from an operation state in which knocking does not occur to an operation state in which knocking can occur, the ignition timing can be erroneously retarded even when knocking has not occurred. This is because, in an operating state where knocking can occur, vibrations not caused by knocking can be larger than in an operating state where knocking does not occur.

  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 and an ignition timing control method for an internal combustion engine that can accurately control the ignition timing. is there.

  An ignition timing control device for an internal combustion engine according to a first aspect of the invention is a means for detecting the vibration intensity of the internal combustion engine, and for calculating a value related to the vibration intensity of the internal combustion engine according to the detected intensity. A calculating means; a setting means for setting a judgment value to be compared with a value relating to the intensity of vibration of the internal combustion engine; a means for setting an ignition timing in accordance with an operating state of the internal combustion engine; and an operating state of the internal combustion engine And a control means for controlling the ignition timing set according to the control by correcting the ignition timing according to the result of comparing the value related to the vibration intensity of the internal combustion engine and the determination value. The setting means includes correction means for correcting the determination value when the difference between the ignition timing set according to the operating state of the internal combustion engine and the corrected ignition timing is equal to or less than a predetermined difference. An internal combustion engine ignition timing control method according to a sixth aspect of the invention has the same requirements as the internal combustion engine ignition timing control apparatus according to the first aspect of the invention.

  According to this configuration, the value related to the vibration intensity of the internal combustion engine is calculated according to the vibration intensity of the internal combustion engine. A determination value to be compared with a value related to the intensity of vibration of the internal combustion engine is set. The ignition timing of the internal combustion engine is set according to the operating state of the internal combustion engine. The ignition timing set according to the operating state of the internal combustion engine is controlled by correcting the ignition timing according to the result of comparing the value related to the vibration intensity of the internal combustion engine and the determination value. For example, if it is considered that knocking has occurred as a result of comparing the value relating to the vibration intensity of the internal combustion engine and the judgment value, the ignition timing is retarded. When the difference between the ignition timing set according to the operating state of the internal combustion engine and the corrected ignition timing is equal to or less than a predetermined difference, the determination value is corrected. Thereby, the determination value can be corrected in an operation state in which knocking does not occur. Therefore, for example, before shifting from an operation state in which knocking does not occur to an operation state in which knocking can occur, the determination value can be corrected in advance so that a preferable determination value is obtained in the operation state in which knocking can occur. As a result, it is possible to provide an ignition timing control device or ignition timing control method for an internal combustion engine that can accurately control the ignition timing.

  In the ignition timing control device for an internal combustion engine according to the second invention, in addition to the configuration of the first invention, the correction means is an operation state in which the operation state of the internal combustion engine is predetermined and the operation of the internal combustion engine is When the difference between the ignition timing set according to the state and the corrected ignition timing is equal to or less than a predetermined difference, a means for correcting the determination value is provided. The ignition timing control method for an internal combustion engine according to the seventh invention has the same requirements as the ignition timing control device for the internal combustion engine according to the second invention.

  According to this configuration, the operation state of the internal combustion engine is a predetermined operation state, and the difference between the ignition timing set according to the operation state of the internal combustion engine and the corrected ignition timing is equal to or less than the predetermined difference. If it is, the determination value is corrected. Accordingly, the operating state in which the determination value is corrected according to the difference between the ignition timing set according to the operating state of the internal combustion engine and the corrected ignition timing is limited to, for example, only the operating state where knocking does not occur. it can. Therefore, unnecessary processing can be omitted.

  In the internal combustion engine ignition timing control apparatus according to the third aspect of the invention, in addition to the configuration of the second aspect of the invention, the setting means is an operation state in which the operation state of the internal combustion engine is predetermined, and the operation of the internal combustion engine. When a difference between the ignition timing set according to the state and the corrected ignition timing is larger than a predetermined difference, a means for stopping correction of the determination value is included. An internal combustion engine ignition timing control method according to an eighth aspect of the invention has the same requirements as the internal combustion engine ignition timing control apparatus according to the third aspect of the invention.

  According to this configuration, the operating state of the internal combustion engine is a predetermined operating state, and the difference between the ignition timing set according to the operating state of the internal combustion engine and the corrected ignition timing is based on the predetermined difference. If it is larger, the correction of the judgment value is stopped. For example, if the correction amount of the ignition timing is large in an operating state in which knocking does not occur, it is considered that some malfunction has occurred, and thus correction of the determination value is stopped. Thereby, it can prevent correcting a judgment value accidentally.

  In the internal combustion engine ignition timing control apparatus according to the fourth aspect of the invention, in addition to the configuration of the first or second aspect of the invention, the setting means includes an ignition timing set according to the operating state of the internal combustion engine and a corrected ignition timing. If the difference is larger than a predetermined difference, means for stopping correction of the determination value is included. An ignition timing control method for an internal combustion engine according to a ninth aspect has the same requirements as the ignition timing control apparatus for an internal combustion engine according to the fourth aspect.

  According to this configuration, when the difference between the ignition timing set according to the operating state of the internal combustion engine and the corrected ignition timing is greater than a predetermined difference, correction of the determination value is stopped. Thereby, it can prevent correcting a judgment value accidentally.

  In the internal combustion engine ignition timing control apparatus according to the fifth aspect of the invention, in addition to the configuration of any one of the first to fourth aspects of the invention, the calculation means increases the intensity of the vibration of the internal combustion engine such that the calculation means increases. Means for calculating a value relating to the intensity of the vibration. The control means includes means for retarding the ignition timing when the value relating to the vibration intensity of the internal combustion engine is larger than the determination value. The correcting means has means for correcting the determination value so as to increase. An internal combustion engine ignition timing control method according to a tenth aspect of the invention has the same requirements as the internal combustion engine ignition timing control apparatus according to the fifth aspect of the invention.

  According to this configuration, the value related to the vibration intensity of the internal combustion engine is calculated so as to increase as the vibration intensity of the internal combustion engine increases. When the value relating to the vibration intensity of the internal combustion engine is larger than the determination value, the ignition timing is retarded. Thereby, when knocking occurs, knocking can be suppressed. When the difference between the ignition timing set according to the operating state of the internal combustion engine and the corrected ignition timing is equal to or less than a predetermined difference, the determination value is corrected so as to increase. This makes it difficult to retard the ignition timing. Therefore, it is possible to reduce the frequency that the ignition timing is retarded unnecessarily. As a result, the ignition timing can be accurately controlled.

  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, an engine 100 of a vehicle equipped with an ignition timing control device according to an embodiment of the present invention will be described. The engine 100 is provided with a plurality of cylinders. 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. The program executed by engine ECU 200 may be recorded on a recording medium such as a CD (Compact Disc) or a DVD (Digital Versatile Disc) and distributed to the market.

  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 set according to the operating state of engine 100. Hereinafter, the ignition timing set according to the operating state of engine 100 is also referred to as basic ignition timing. When knocking occurs, the ignition timing is retarded from the basic ignition timing.

  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. When the intake valve 116 is opened, the air-fuel mixture is introduced into the combustion chamber. When the exhaust valve 118 is opened, the exhaust gas is discharged from the combustion chamber.

  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. The engine ECU 200 performs arithmetic processing based on signals transmitted from the sensors and the ignition switch 312, a map and a program stored in a ROM (Read Only Memory) 202, so that the engine 100 enters a desired operating state. Control 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, as shown in FIG. 2, vibration of a frequency included in frequency bands A to C is generated in engine 100. Therefore, in the present embodiment, vibrations in a wide frequency band D including the frequency bands A to C are detected.

  As shown in FIG. 3, engine ECU 200 includes an A / D (analog / digital) conversion unit 400, a band pass filter 410, and an integration unit 420.

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

  The integrating unit 420 calculates an integrated value (hereinafter also referred to as a 5-degree integrated value) obtained by integrating the signal selected by the band-pass filter 410, that is, the intensity of vibration by 5 degrees at the crank angle. Thereby, as shown in FIG. 4, the vibration waveform of the frequency band D is detected.

  The detected vibration waveform is used to calculate a correlation coefficient K that represents the degree to which the vibration waveform is similar to the knock waveform model (represents the difference between the shape of the vibration waveform and the shape of the knock waveform model). As shown in FIG. 5, it is detected in the range of the crank angle after the crank angle at which the strength is the largest, that is, the crank angle at which the strength is peak, which is larger than the strength of the adjacent crank angle. The correlation coefficient K is calculated by comparing the generated vibration waveform with the knock waveform model.

  The knock waveform model is determined as a reference for the vibration waveform of engine 100 when knocking occurs. In the present embodiment, the strength of the knock waveform model is set every time it is compared with the vibration waveform. More specifically, the maximum intensity value in the knock waveform model is set to be the same as the intensity (peak value of intensity) greater than the adjacent intensity in the vibration waveform.

  On the other hand, the intensity other than the maximum value is set according to the engine speed NE and the load of the engine 100. More specifically, the attenuation rate of the intensity at the adjacent crank angle is set according to a map having the engine speed NE and the load of engine 100 as parameters.

  For example, when an intensity of 20 degrees is set as the crank angle with an attenuation rate of 25%, the intensity decreases by 25% as shown in FIG. The method for setting the strength of the knock waveform model is not limited to this.

  The correlation coefficient K is calculated by calculating the absolute value (deviation amount) of the difference between the intensity in the vibration waveform and the intensity in the knock waveform model for each crank angle (every 5 degrees). The absolute value of the difference between the intensity in the vibration waveform and the intensity in the knock waveform model may be calculated for each crank angle other than 5 degrees.

  The absolute value of the difference for each crank angle between the intensity in the vibration waveform and the intensity in the knock waveform model is set to ΔS (I) (I is a natural number). As indicated by hatching in FIG. 7, a value obtained by summing the vibration intensities of the knock waveform model, that is, the area of the knock waveform model is S. The correlation coefficient K is calculated using the following equation (1).

K = (S−ΣΔS (I)) / S (1)
ΣΔS (I) is the sum of ΔS (I). Note that the method of calculating the correlation coefficient K is not limited to this.

  In the present embodiment, in addition to correlation coefficient K, knock magnitude N is calculated. Knock intensity N is calculated using 90 degree integrated value lpkknk obtained by summing up the intensity (5 degree integrated value) in the vibration waveform, as indicated by hatching in FIG. Note that the maximum intensity in the vibration waveform may be used instead of the 90-degree integrated value lpkknk.

  A value representing the intensity of vibration of engine 100 in a state where knocking has not occurred in engine 100 is represented as BGL (Back Ground Level). Knock strength N is calculated using the following equation (2).

N = lpkknk / BGL (2)
The method for calculating knock magnitude N is not limited to this. When calculating knock magnitude N, a logarithmic conversion value of 90-degree integrated value lpkknk is used. BGL is a value obtained by subtracting the product of the standard deviation σ and a coefficient (for example, “1”) from the median value VMED in the frequency distribution representing the frequency (number of times, also referred to as probability) at which each 90-degree integrated value lpkknk is detected. Is calculated as Note that the BGL calculation method is not limited to this, and the BGL may be stored in the ROM 202. Further, when creating the frequency distribution, a logarithmic conversion value of the 90-degree integrated value lpkknk is used.

  In the present embodiment, whether or not knocking has occurred is determined for each ignition using the correlation coefficient K calculated based on the shape of the vibration waveform and the knock intensity N calculated based on the strength of the vibration waveform. Is determined. Whether or not knocking has occurred is determined for each cylinder. If correlation coefficient K is equal to or greater than threshold value K (1) and knock magnitude N is equal to or greater than determination value VJ, it is determined that knocking has occurred. Otherwise, it is determined that knocking has not occurred.

  If it is determined that knocking has occurred, the ignition timing is retarded by a predetermined amount. If it is determined that knocking has not occurred, the ignition timing is advanced by a predetermined amount.

  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 VJ (initial value of the determination value VJ 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 VJ and determine whether knocking has occurred using the determination value VJ according to the actually detected intensity. Therefore, in the present embodiment, determination value VJ is corrected every predetermined ignition cycle, for example, every 200 ignition cycles.

  The function of engine ECU 200 will be described with reference to FIG. Note that the functions described below may be realized by software or hardware.

  Engine ECU 200 includes an ignition timing setting unit 500, a crank angle detection unit 600, an intensity detection unit 602, a waveform detection unit 604, a correlation coefficient calculation unit 606, a 90-degree integrated value calculation unit 608, and a calculation unit 610. And a determination unit 612, an ignition timing control unit 614, and a determination value setting unit 700.

  Ignition timing setting unit 500 sets the basic ignition timing according to the operating state of engine 100. As shown in FIG. 10, the basic ignition timing is set according to a map having the engine speed NE and the load KL as parameters.

  In the present embodiment, MBT (Minimum advance for Best Torque) in an operating state (operating region) where engine speed NE is smaller than threshold value NE (0) and load KL is smaller than threshold value KL (0). ) Is set as the basic ignition timing. This is because knocking hardly occurs when the engine speed NE is smaller than the threshold value NE (0) and the load KL is smaller than the threshold value KL (0). MBT represents an ignition timing at which the output of engine 100 is maximized.

  The load KL is calculated based on the intake air amount detected by the air flow meter 314 and the engine speed NE. In addition, since the method of calculating load KL should just use a known general technique, those detailed description is not repeated here.

  The crank angle detection unit 600 detects the crank angle based on the signal transmitted from the crank position sensor 306.

  Based on the signal transmitted from knock sensor 300, intensity detector 602 detects the intensity of vibration at the knock detection gate. The intensity of vibration is detected corresponding to the crank angle. The intensity of vibration is expressed 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 waveform detection unit 604 detects the vibration waveform at the knock detection gate by integrating the vibration intensity by 5 degrees in terms of the crank angle.

  The correlation coefficient calculation unit 606 calculates a correlation coefficient K that represents the degree to which the vibration waveform is similar to the knock waveform model (represents the difference between the shape of the vibration waveform and the shape of the knock waveform model).

  The 90-degree integrated value calculation unit 608 calculates a 90-degree integrated value lpkknk that is the sum of the intensities (5-degree integrated value) in the vibration waveform.

  Calculation unit 610 calculates knock magnitude N using 90-degree integrated value lpkknk. Determination unit 612 determines whether or not knocking has occurred for each ignition using correlation coefficient K and knock magnitude N. If correlation coefficient K is equal to or greater than threshold value K (1) and knock magnitude N is equal to or greater than determination value VJ, it is determined that knocking has occurred. Otherwise, it is determined that knocking has not occurred.

  The ignition timing control unit 614 performs control by correcting the ignition timing according to whether knocking has occurred. If it is determined that knocking has occurred, the ignition timing is retarded by a predetermined amount. If it is determined that knocking has not occurred, the ignition timing is advanced by a predetermined amount. The ignition timing is advanced or retarded, for example, in the range from MBT to the retard limit value. That is, when it is most advanced, the ignition timing is MBT. When retarded most, the ignition timing is the retard limit value.

  Determination value setting unit 700 sets determination value VJ to be compared with knock magnitude N. The determination value setting unit 700 includes a frequency distribution creation unit 702, a first correction unit 711, a second correction unit 712, a third correction unit 713, and a stop unit 714.

  As shown in FIG. 11, the frequency distribution creating unit 702 creates a frequency distribution of the 90-degree integrated value lpkknk calculated in each ignition cycle. When creating the frequency distribution, the logarithm conversion value of the 90-degree integrated value lpkknk is used.

  In the frequency distribution, as shown in FIG. 11, median value VMED and standard deviation σ of 90-degree integrated value lpkknk are calculated. In the present embodiment, median value VMED and standard deviation σ approximated to a median value and a standard deviation calculated based on a plurality of (for example, 200 ignition cycles) 90-degree integrated values lpkknk are set to 1 ignition by the following calculation method. Calculated for each cycle.

  When the 90 degree integrated value lpkknk calculated this time is larger than the median value VMED calculated last time, a value obtained by adding a predetermined value C (1) to the median value VMED calculated last time is the current median value VMED. Is calculated as On the other hand, when the 90-degree integrated value lpkknk calculated this time is smaller than the median value VMED calculated last time, a predetermined value C (2) (for example, C (2) is C) from the median value VMED calculated last time. A value obtained by subtracting (the same value as (1)) is calculated as the current median value VMED.

  When the 90 degree integrated value lpkknk calculated this time is smaller than the median value VMED calculated last time and larger than the value obtained by subtracting the standard deviation σ calculated last time from the median value VMED calculated last time, it is calculated last time. A value obtained by subtracting a value obtained by doubling a predetermined value C (3) from the standard deviation σ is calculated as the current standard deviation σ. Conversely, when the 90-degree integrated value lpkknk calculated this time is larger than the median value VMED calculated last time, or smaller than the value obtained by subtracting the standard deviation σ calculated last time from the median value VMED calculated last time 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 calculated as the current standard deviation σ. In addition, the calculation method of median value VMED and standard deviation (sigma) is not limited to this. Further, the initial values of median value VMED and standard deviation σ may be preset values or “0”.

  Knock determination level VKD is calculated using median value VMED and standard deviation σ. As shown in FIG. 11, a value obtained by adding the product of coefficient U (U is a constant, for example, U = 3) and standard deviation σ to median value VMED is knock determination level VKD. The method for calculating knock determination level VKD is not limited to this.

  The coefficient U is a coefficient obtained from data or knowledge obtained through experiments or the like. The 90-degree integrated value lpkknk, which is larger than the knock determination level VKD when U = 3, substantially matches the 90-degree integrated value lpkknk in the ignition cycle in which knocking actually occurs. A value other than “3” may be used as the coefficient U.

  The first correction unit 711 determines a predetermined correction when the knock occupancy KC counted as the ratio (frequency) of the 90-degree integrated value lpkknk larger than the knock determination level VKD is equal to or greater than the threshold value KC (0). The determination value VJ is corrected so as to be reduced by the amount A (1). Further, when knock occupancy KC is smaller than threshold value KC (0), first correction unit 711 corrects determination value VJ to be increased by a predetermined correction amount A (2).

  Second correction unit 712 determines in advance when the number of 90 degree integrated values lpkknk greater than determination value VJ is equal to or greater than threshold value C (0) during a predetermined number of ignition cycles (for example, 200 ignition cycles). The determination value VJ is corrected so as to increase by the correction amount A (3).

  The second correction unit 712 has a 90 degree integrated value lpkknk greater than the determination value VJ in an operating state in which the engine speed NE is smaller than the threshold value NE (0) and the load KL is smaller than the threshold value KL (0). When the number is equal to or greater than the threshold value C (0), the determination value VJ is corrected.

  The third correction unit 713 is predetermined when the difference between the basic ignition timing and the corrected ignition timing, that is, the actual ignition timing (basic ignition timing−corrected ignition timing) is equal to or less than the threshold value ΔCA. The determination value VJ is corrected so as to increase by the correction amount A (4). More specifically, when the average value of the difference between the basic ignition timing and the corrected ignition timing in a predetermined number of ignition cycles (for example, 200 ignition cycles) is equal to or less than the threshold value ΔCA, the determination value VJ is corrected.

  Further, the third correction unit 713 corrects the basic ignition timing and the ignition timing corrected in the operating state in which the engine speed NE is smaller than the threshold value NE (0) and the load KL is smaller than the threshold value KL (0). Is equal to or less than the threshold value ΔCA, the determination value VJ is corrected.

  Stop unit 714 stops correction of determination value VJ when the difference between the basic ignition timing and the corrected ignition timing is greater than threshold value ΔCA. More specifically, when the average value of the difference between the basic ignition timing and the corrected ignition timing in a predetermined number of ignition cycles (for example, 200 ignition cycles) is larger than threshold value ΔCA, determination value VJ Correction is stopped.

  Stop unit 714 also determines whether the basic ignition timing and the corrected ignition timing are in an operating state where engine speed NE is smaller than threshold value NE (0) and load KL is smaller than threshold value KL (0). When the difference is larger than the threshold value ΔCA, the correction of the determination value VJ is stopped.

  A control structure of a program executed by engine ECU 200 will be described with reference to FIGS.

  In step (hereinafter step is abbreviated as S) 100, engine ECU 200 detects the crank angle based on the signal transmitted from crank position sensor 306. In S102, engine ECU 200 detects the intensity of vibration of engine 100 in accordance with the crank angle based on the signal transmitted from knock sensor 300.

  In S104, engine ECU 200 calculates a 5-degree 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. A vibration waveform of engine 100 is detected.

  In S106, engine ECU 200 calculates correlation coefficient K. In S108, engine ECU 200 calculates 90-degree integrated value lpkknk. In S110, engine ECU 200 calculates knock magnitude N.

  In S120, engine ECU 200 determines whether or not correlation coefficient K is greater than or equal to threshold value K (1) and knock magnitude N is greater than or equal to determination value VJ. If correlation coefficient K is equal to or greater than threshold value K (1) and knock magnitude N is equal to or greater than determination value VJ (YES in S120), the process proceeds to S122. If not (NO in S120), the process proceeds to S126.

  In S122, engine ECU 200 determines that knocking has occurred in engine 100. In S124, engine ECU 200 retards the ignition timing. In S126, engine ECU 200 determines that knocking has not occurred in engine 100. In S128, engine ECU 200 advances the ignition timing.

  Referring to FIG. 13, in S200, engine ECU 200 determines whether or not the number of ignition cycles after correcting previous determination value VJ is equal to or greater than a predetermined number. If the number of ignition cycles after correcting previous determination value VJ is equal to or greater than a predetermined number (YES in S200), the process proceeds to S202. If not (NO in S200), the process proceeds to S240.

  In S202, engine ECU 200 determines whether engine speed NE is smaller than threshold value NE (0) and load KL is smaller than threshold value KL (0). If engine speed NE is smaller than threshold value NE (0) and load KL is smaller than threshold value KL (0) (YES in S202), the process proceeds to S210. If not (NO in S202), the process proceeds to S230.

  In S210, engine ECU 200 determines whether or not the number of 90 degree integrated values lpkknk greater than determination value VJ is equal to or greater than threshold value C (0) during a predetermined number of ignition cycles. If the number of 90-degree integrated values lpkknk greater than determination value VJ is equal to or greater than threshold value C (0) (YES in S210), the process proceeds to S212. If not (NO in S212), the process proceeds to S220.

  In S212, engine ECU 200 corrects determination value VJ so as to increase by correction amount A (3).

  In S220, engine ECU 200 determines whether or not the average value of the difference between the basic ignition timing and the corrected ignition timing is equal to or less than threshold value ΔCA. If the average value of the difference between the basic ignition timing and the corrected ignition timing is equal to or smaller than threshold value ΔCA (YES in S220), the process proceeds to S222. If not (NO in S220), the process proceeds to S224.

  In S222, engine ECU 200 corrects determination value VJ so as to increase by correction amount A (4). In S224, engine ECU 200 stops the correction of determination value VJ.

  In S230, engine ECU 200 corrects determination value VJ according to knock occupancy KC. When knock occupancy KC is equal to or greater than threshold value KC (0), determination value VJ is corrected so as to decrease by a predetermined correction amount A (1). When knock occupancy KC is smaller than threshold value KC (0), determination value VJ is corrected so as to increase by a predetermined correction amount A (2).

  In S240, engine ECU 200 creates (updates) a frequency distribution of 90-degree integrated value lpkknk. That is, median value VMED, standard deviation σ, and knock determination level VKD are set (updated). Thereafter, the process returns to S100.

  In addition, the order which performs the process of S100-S240 is not restricted to the order shown in FIG. 12 and FIG. You may make it perform the process of S100-S240 in the order different from the order shown in FIG. 12 and FIG. The process of S202 may be performed immediately before S220.

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

  During operation of engine 100, the crank angle is detected based on the signal transmitted from crank position sensor 306 (S100). Based on the signal transmitted from knock sensor 300, the intensity of vibration of engine 100 is detected in correspondence with the crank angle (S102). A vibration waveform of engine 100 is detected by calculating a 5-degree integrated value obtained by integrating the output voltage value of knock sensor 300 every 5 degrees in crank angle (S104).

  In order to determine whether knocking has occurred or not based on the shape of the waveform, a correlation coefficient K is calculated using a knock waveform model (S106). Further, in order to determine whether or not the vibration generated due to knocking is included in the vibration waveform based on the strength, a 90-degree integrated value lpkknk is calculated (S108). Knock strength N is calculated by dividing 90-degree integrated value lpkknk by BGL (S110).

  When correlation coefficient K is equal to or greater than threshold value K (1) and knock intensity N is equal to or greater than determination value VJ (YES in S120), the detected waveform shape is similar to the waveform shape due to knocking. It can be said that the vibration strength is high. That is, it is very likely that knocking has occurred. In this case, it is determined that knocking has occurred in engine 100 (S122). In order to suppress knocking, the ignition timing is retarded (S124).

  On the other hand, when correlation coefficient K is smaller than threshold value K (1), or when knock magnitude N is smaller than determination value VJ, it is determined that knocking has not occurred in engine 100 (S126). In this case, the ignition timing is advanced (S128).

  By the way, 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 VJ stored in the ROM 202 (initial value of the determination value VJ at the time of shipment). 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 VJ and determine whether knocking has occurred using the determination value VJ according to the actually detected intensity.

  Therefore, in the present embodiment, determination value VJ is corrected using the frequency distribution of 90-degree integrated value lpkknk. If the number of ignition cycles after correcting the previous determination value VJ is less than the predetermined number (NO in S200), a frequency distribution of 90-degree integrated value lpkknk is created using 90-degree integrated value lpkknk. (S240). As a result, median value VMED, standard deviation σ, and knock determination level VKD are set.

  If the number of ignition cycles after correcting the previous determination value VJ is equal to or greater than a predetermined number (YES in S200), engine speed NE is smaller than threshold value NE (0) and load KL Is smaller than the threshold value KL (0) (S202).

  When engine speed NE is equal to or greater than threshold value NE (0), or when load KL is equal to or greater than threshold value KL (0) (NO in S202), determination value VJ is set according to knock occupancy KC. It is corrected (S230).

  When knock occupancy KC is equal to or greater than threshold value KC (0), determination value VJ is corrected so as to decrease by correction amount A (1). Thereby, it can be easily determined that knocking has occurred. Therefore, the frequency of retarding the ignition timing can be increased. As a result, the number of times that knocking occurs can be reduced.

  When knock occupancy KC is smaller than threshold value KC (0), determination value VJ is corrected so as to increase by correction amount A (2). Thereby, it can be made difficult to determine that knocking has occurred. For this reason, the frequency at which the ignition timing is advanced can be increased. As a result, the output of engine 100 can be increased.

  By the way, when the operating state of the engine 100 is low load and low rotation, knocking hardly occurs. Therefore, when engine 100 is operating at a low load and a low speed, correction of determination value VJ using knock occupancy KC cannot be performed.

  Therefore, when engine speed NE is smaller than threshold value NE (0) and load KL is smaller than threshold value KL (0) (YES in S202), determination value VJ is not used without knock occupancy KC. It is corrected.

  If the number of 90-degree integrated values lpkknk greater than determination value VJ is equal to or greater than threshold value C (0) during the predetermined number of ignition cycles (YES in S210), mechanical vibrations of engine 100 itself are not affected. It can be said that the judgment value VJ is low. In this case, the determination value VJ is corrected so as to increase by the correction amount A (3) (S212).

  If engine speed NE is smaller than threshold value NE (0) and load KL is smaller than threshold value KL (0) (YES in S202), knocking hardly occurs. Therefore, there is no problem even if the frequency at which the ignition timing is advanced is increased as a result of the correction so that the determination value VJ is increased.

  By the way, when the determination value VJ is corrected using the number of 90-degree integrated values lpkknk larger than the determination value VJ, as shown in FIG. 14, the lower the engine speed NE, the lower the determination value VJ. This is because knocking hardly occurs, and therefore, the 90-degree integrated value lpkknk larger than the determination value VJ may not be detected.

  If the determination value VJ remains small and changes to an operating state in which mechanical vibration of the engine 100 itself increases, it may be erroneously determined that knocking has occurred although knocking has not occurred. In this case, the ignition timing is retarded by mistake.

  Therefore, during the predetermined number of ignition cycles, if the number of 90-degree integrated values lpkknk greater than determination value VJ is less than threshold value C (0) (NO in S210), ignition is corrected to the basic ignition timing. It is determined whether or not the average value of the difference from the time is equal to or less than a threshold value ΔCA (S220).

  If the average difference between the basic ignition timing and the corrected ignition timing is equal to or smaller than threshold value ΔCA (YES in S220), it can be said that knocking hardly occurs. In this case, the determination value VJ is corrected so as to increase by the correction amount A (4) (S222).

  On the other hand, if the average value of the difference between the basic ignition timing and the corrected ignition timing is greater than threshold value ΔCA (NO in S220), it is determined that knocking has occurred in the low load and low rotation state. . In this case, some trouble may have occurred. Therefore, the correction of the determination value VJ is stopped (S224). As a result, it is possible to prevent the determination value VJ from being erroneously corrected.

  As described above, according to the ignition timing control apparatus according to the present embodiment, knock magnitude N corresponding to the intensity of engine vibration is calculated. When knock magnitude N is equal to or greater than determination value VJ, the ignition timing is retarded. If the difference between the basic ignition timing determined according to the operating state of the engine and the ignition timing corrected according to the presence or absence of knocking is equal to or less than a threshold value ΔCA, a determination value VJ to be compared with the knock intensity N is It is corrected. As a result, the determination value can be corrected in advance in an operating state in which knocking does not occur. Therefore, for example, before shifting from an operation state in which knocking does not occur to an operation state in which knocking can occur, the determination value can be corrected in advance so that a preferable determination value is obtained in the operation state in which knocking can occur. As a result, the ignition timing can be accurately controlled.

  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 an engine. 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 engine ECU. It is a figure which shows the vibration waveform of an engine. It is the figure which compared the vibration waveform and the knock waveform model. It is a figure which shows a knock waveform model. It is a figure which shows the area S of a knock waveform model. It is a figure which shows 90 degree | times integrated value lpkknk. It is a functional block diagram of engine ECU. It is the map which defined basic ignition timing. It is a figure which shows frequency distribution of 90 degree | times integrated value lpkknk. It is FIG. (1) which shows the control structure of the program which engine ECU performs. It is FIG. (2) which shows the control structure of the program which engine ECU performs. It is a figure which shows transition of the judgment value VJ.

Explanation of symbols

  100 engine, 104 injector, 106 spark plug, 110 crankshaft, 116 intake valve, 118 exhaust valve, 200 engine ECU, 202 ROM, 300 knock sensor, 302 water temperature sensor, 304 timing rotor, 306 crank position sensor, 308 throttle opening Sensor, 310 Vehicle speed sensor, 312 Ignition switch, 314 Air flow meter, 320 Auxiliary battery, 400 A / D converter, 410 Bandpass filter, 420 Accumulator, 500 Ignition timing setting unit, 600 Crank angle detector, 602 Strength detection Unit, 604 waveform detection unit, 606 correlation coefficient calculation unit, 608 90-degree integrated value calculation unit, 610 calculation unit, 612 determination unit, 614 ignition timing control unit, 700 determination value setting unit, 7 2 frequency distribution creation unit, 711 first correcting unit, 712 second corrector, 713 third correction unit, 714 stop.

Claims (10)

Means for detecting the intensity of vibration of the internal combustion engine;
Calculating means for calculating a value related to the intensity of vibration of the internal combustion engine according to the detected intensity;
Setting means for setting a determination value to be compared with a value related to the intensity of vibration of the internal combustion engine;
Means for setting the ignition timing according to the operating state of the internal combustion engine;
Control means for controlling the ignition timing set according to the operating state of the internal combustion engine by correcting the ignition timing according to a result of comparing the value relating to the vibration intensity of the internal combustion engine and the determination value;
The setting means includes correction means for correcting the determination value when a difference between an ignition timing set according to an operating state of the internal combustion engine and the corrected ignition timing is equal to or less than a predetermined difference. An ignition timing control device for an internal combustion engine.   The correction means is an operation state in which the operation state of the internal combustion engine is determined in advance, and a difference between the ignition timing set according to the operation state of the internal combustion engine and the corrected ignition timing is determined in advance. The ignition timing control device for an internal combustion engine according to claim 1, further comprising means for correcting the determination value when the difference is equal to or smaller than the difference.   The setting means is configured so that an operating state of the internal combustion engine is the predetermined operating state, and a difference between the ignition timing set according to the operating state of the internal combustion engine and the corrected ignition timing is The ignition timing control device for an internal combustion engine according to claim 2, further comprising means for stopping the correction of the determination value when the difference is larger than a predetermined difference.   The setting means is means for stopping correction of the determination value when a difference between the ignition timing set according to the operating state of the internal combustion engine and the corrected ignition timing is larger than the predetermined difference. The ignition timing control device for an internal combustion engine according to claim 1, comprising: The calculating means includes means for calculating a value related to the vibration intensity of the internal combustion engine so as to increase as the vibration intensity of the internal combustion engine increases.
The control means includes means for retarding the ignition timing when a value related to the vibration intensity of the internal combustion engine is greater than the determination value,
The ignition timing control device for an internal combustion engine according to any one of claims 1 to 4, wherein the correction means includes means for correcting the determination value so as to increase. Detecting the intensity of vibration of the internal combustion engine;
Calculating a value related to the intensity of vibration of the internal combustion engine according to the detected intensity;
Setting a determination value to be compared with a value related to the intensity of vibration of the internal combustion engine;
Setting the ignition timing according to the operating state of the internal combustion engine;
Controlling the ignition timing set according to the operating state of the internal combustion engine by correcting the ignition timing according to the result of comparing the value relating to the intensity of vibration of the internal combustion engine and the determination value,
The step of setting the determination value is a step of correcting the determination value when a difference between an ignition timing set according to an operating state of the internal combustion engine and the corrected ignition timing is equal to or less than a predetermined difference. An ignition timing control method for an internal combustion engine, comprising:   The step of correcting the determination value is a difference between an ignition timing set according to the operating state of the internal combustion engine and the corrected ignition timing when the operating state of the internal combustion engine is a predetermined operating state. The ignition timing control method for an internal combustion engine according to claim 6, further comprising a step of correcting the determination value when the difference is equal to or less than the predetermined difference.   In the step of setting the determination value, the operation state of the internal combustion engine is the predetermined operation state, and the ignition timing set according to the operation state of the internal combustion engine and the corrected ignition timing are set. The ignition timing control method for an internal combustion engine according to claim 7, further comprising a step of stopping correction of the determination value when the difference is larger than the predetermined difference.   The step of setting the determination value stops the correction of the determination value when the difference between the ignition timing set according to the operating state of the internal combustion engine and the corrected ignition timing is larger than the predetermined difference. An ignition timing control method for an internal combustion engine according to claim 6 or 7, comprising the step of: The step of calculating a value related to the vibration intensity of the internal combustion engine includes a step of calculating a value related to the vibration intensity of the internal combustion engine such that the value is larger as the vibration intensity of the internal combustion engine is larger.
The step of controlling the ignition timing includes a step of retarding the ignition timing when a value related to the intensity of vibration of the internal combustion engine is larger than the determination value,
The ignition timing control method for an internal combustion engine according to any one of claims 6 to 9, wherein the step of correcting the determination value includes a step of correcting the determination value so as to increase.

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