JP4919939B2 - Ignition timing control device and ignition timing control method for internal combustion engine - Google Patents

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 the ignition timing according to a result of comparing the intensity of vibration 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 Application Laid-Open No. 2007-198317 (Patent Document 1) discloses a detection unit for detecting the intensity of vibration generated in an internal combustion engine and the intensity of vibration caused by knocking based on the intensity of vibration generated in the internal combustion engine. Based on the result of comparing the knock intensity with a predetermined determination value, a control section for controlling the ignition timing of the internal combustion engine, and a frequency of occurrence of knocking When the difference between the correction unit for correcting the determination value and the intensity of vibration generated in the internal combustion engine and the determination value is larger than a predetermined value, the determination value is determined as the intensity of vibration generated in the internal combustion engine. An ignition timing control device for an internal combustion engine is disclosed, including a setting unit for setting to a value determined according to the above.

According to the ignition timing control device described in this publication, the knock magnitude relating to the magnitude of vibration caused by knocking is calculated based on the magnitude of 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. 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. Further, when the difference between the intensity of vibration generated in the internal combustion engine and the determination value is larger than a predetermined value, the determination value is set to a value determined according to the intensity of vibration generated in the internal combustion engine. For example, the determination value is set to a value obtained by adding a predetermined value to the maximum value of the intensity of vibration generated in the internal combustion engine. Thereby, the determination value can be brought close to the intensity of vibration actually generated in the internal combustion engine. Therefore, it is determined that knocking has not occurred despite the occurrence of knocking, and the ignition timing has been advanced, or it has been determined that knocking has occurred although knocking has not occurred, and the ignition timing has been reached. Can be prevented from being delayed.
JP 2007-198317 A

  However, when correcting the determination value based on the occurrence frequency of knocking as in the ignition timing control device described in JP 2007-198317 A, if the occurrence frequency of knocking is erroneously determined, the determination value is erroneously determined. It can be corrected. In this case, the ignition timing can be delayed or advanced by mistake.

  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.

  In the ignition timing control apparatus for an internal combustion engine according to the first invention, means for detecting the vibration intensity of the internal combustion engine in a plurality of ignition cycles and a first value smaller than the median value of the intensity are calculated. According to the result of comparing the second value and the first determination value, the calculating means for calculating the second value by dividing the intensity by the first value, Control means for controlling the ignition timing, setting means for setting a second determination value larger than the median value of the intensity, and for counting the frequency at which an intensity greater than the second determination value is detected One of the intensity and the second value is determined in advance according to the means, the frequency at which the intensity equal to or higher than the second determination value is detected, and the correction means for correcting the first determination value. If the threshold is smaller than And a stopping means for stopping at least one of the counts. The ignition timing control method according to the sixth invention has the same requirements as the ignition timing control device according to the first invention.

  According to this configuration, the intensity of vibration of the internal combustion engine is detected in a plurality of ignition cycles. A first value smaller than the detected median value is calculated. Thereby, BGL (Back Ground Level) which becomes a reference of the intensity of vibration can be obtained. A second value is calculated by dividing the intensity by the first value. Thereby, the 2nd value which shows the relative magnitude | size with the detected intensity | strength and the reference | standard of the intensity | strength of a vibration can be obtained. The ignition timing of the internal combustion engine is controlled according to the result of comparing the second value and the first determination value. For example, when the second value is larger than the first determination value, there is a high possibility that knocking has occurred. Therefore, the ignition timing is retarded. For the purpose of correcting the first determination value, a second determination value larger than the median value of the intensity is set. The frequency at which the intensity equal to or higher than the second determination value is detected is counted. When the frequency at which the intensity equal to or higher than the second determination value is detected is high, the possibility of frequent knocking is high. Therefore, the first determination value is corrected according to the frequency at which the intensity equal to or higher than the second determination value is detected. For example, if the calculated frequency is greater than a predetermined frequency, the first determination value is corrected to be small. Thereby, it is possible to easily retard the ignition timing. By the way, for example, when the load of the internal combustion engine changes from a low state to a high state, the detected intensity suddenly increases. Therefore, even if knocking does not occur, the frequency at which an intensity greater than the second determination value is detected can be increased. In this case, the first determination value can be corrected by mistake. Even if knocking does not occur, the second value calculated by dividing the intensity by the first value can be increased. In this case, the ignition timing can be retarded even if knocking does not occur. Therefore, when either one of the intensity and the second value is smaller than a predetermined threshold value, at least one of the ignition timing control and the frequency count is stopped. Thus, the ignition timing control or frequency count can be stopped until the intensity of vibration detected in the internal combustion engine becomes sufficiently large. Therefore, when the load of the internal combustion engine changes from a low state to a high state, it is possible to prevent the first determination value from being corrected erroneously and the ignition timing from being erroneously retarded. 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 stop means performs ignition when either one of the intensity and the second value is smaller than the threshold value. Means for stopping both timing control and frequency counting are included. The ignition timing control method according to the seventh invention has the same requirements as the ignition timing control device according to the second invention.

  According to this configuration, when either one of the intensity and the second value is smaller than a predetermined threshold value, both the ignition timing control and the frequency count are stopped. Thereby, the control of the ignition timing and the counting of the frequency can be stopped until the intensity of vibration detected in the internal combustion engine becomes sufficiently large. Therefore, when the load of the internal combustion engine changes from a low state to a high state, it is possible to prevent the first determination value from being corrected erroneously and the ignition timing from being erroneously retarded. As a result, the ignition timing can be accurately controlled.

  In the ignition timing control apparatus for an internal combustion engine according to the third invention, in addition to the configuration of the first or second invention, the calculating means calculates the product of the standard deviation of the intensity and the first coefficient from the median value of the intensity. Means for calculating the first value by subtraction are included. The setting means includes means for setting the second determination value by adding the product of the standard deviation of the intensity and the second coefficient to the median value of the intensity. The ignition timing control method according to the eighth invention has the same requirements as the ignition timing control device according to the third invention.

  According to this configuration, the first value can be calculated by subtracting the product of the standard deviation of the intensity and the first coefficient from the median value of the intensity, and the standard deviation of the intensity and the second coefficient can be calculated. The second determination value can be set by adding the product to the median intensity.

  In the ignition timing control device for an internal combustion engine according to the fourth invention, in addition to the configuration of any one of the first to third inventions, the control means performs ignition when the second value is larger than the first determination value. Includes means for retarding the time. The ignition timing control method according to the ninth aspect has the same requirements as the ignition timing control apparatus according to the fourth aspect.

  According to this configuration, when the second value is larger than the first determination value, the ignition timing is retarded. Thereby, when the detected intensity is large, that is, when knocking occurs, the ignition timing can be retarded. Therefore, the number of times that knocking occurs can be reduced.

  In the ignition timing control apparatus for an internal combustion engine according to the fifth aspect of the invention, in addition to the configuration of the fourth aspect of the invention, the correction means is configured such that the frequency at which the intensity equal to or higher than the second determination value is detected is higher than a predetermined frequency. Means for correcting the first determination value to be smaller when it is larger, and the first determination value when the frequency at which the intensity equal to or higher than the second determination value is detected is smaller than a predetermined frequency. And means for correcting so as to increase. The ignition timing control method according to the tenth invention has the same requirements as the ignition timing control device according to the fifth invention.

  According to this configuration, when the frequency at which the intensity equal to or greater than the second determination value is detected is greater than a predetermined frequency, the first determination value is corrected to be small. Thereby, it is possible to easily retard the ignition timing. Therefore, the number of times that knocking occurs can be further reduced. When the frequency at which the intensity equal to or higher than the second determination value is detected is smaller than a predetermined frequency, the first determination value is corrected so as to increase. This makes it difficult to retard the ignition timing. Therefore, the output of the internal combustion engine can be made difficult to decrease.

  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 standard deviation σ and a coefficient (for example, “1”) from median value VMED in a frequency distribution representing the frequency (number of times, also called 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. A determination unit 612, an ignition timing control unit 614, a determination value setting unit 700, and a stop unit 800.

  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. Determination value setting unit 700 includes a frequency distribution creation unit 702, a BGL calculation unit 704, a knock determination level calculation unit 706, a count unit 708, and a correction unit 710.

  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 median value and standard deviation calculated based on a plurality of (for example, 200 ignition cycles) 90 degree integrated value 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”.

  The BGL calculation unit 704 calculates BGL by subtracting the product of the standard deviation σ and the coefficient from the median value VMED.

  Knock determination level calculation unit 706 calculates (sets) knock determination level VKD 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.

  Counting unit 708 counts the ratio (frequency) of 90-degree integrated value lpkknk that is greater than knock determination level VKD in a predetermined number of ignition cycles (for example, 200 ignition cycles) as knock occupancy KC.

  When knock occupancy KC is equal to or greater than threshold value KC (0), correction unit 710 corrects determination value VJ so that it is reduced by a predetermined correction amount A (1). Further, when knock occupancy KC is smaller than threshold value KC (0), correction unit 710 corrects determination value VJ so as to increase by a predetermined correction amount A (2).

  Stop unit 800 stops the determination of knocking by determination unit 612, that is, the control of the ignition timing by ignition timing control unit 614, when knock magnitude N is smaller than a predetermined minimum guard value. Stop unit 800 stops counting of knock occupancy KC by counting unit 708 when knock magnitude N is smaller than a predetermined minimum guard value. The setting (updating) of median value VMED, standard deviation σ, and knock determination level VKD is pending.

  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 S112, engine ECU 200 determines whether knock magnitude N is smaller than the minimum guard value or not. If knock magnitude N is smaller than the minimum guard value (YES in S112), the process proceeds to S114. If not (NO in S112), the process proceeds to S120.

  In S114, engine ECU 200 stops knocking determination, ignition timing control, and knock occupancy KC count. Thereafter, the process proceeds to S206.

  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, at S200, engine ECU 200 counts knock occupancy KC. In S202, 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 S202), the process proceeds to S204. If not (NO in S202), the process proceeds to S206.

  In S204, 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 S206, 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.

  Note that the order in which the processes of S100 to S206 are performed is not limited to the order shown in FIGS. The processes of S100 to S206 may be executed in an order different from the order shown in FIGS.

  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).

  If knock magnitude N is greater than the minimum guard value (NO in S112), it is determined whether or not knocking has occurred. 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. In order to correct determination value VJ, knock occupancy KC is counted (S200). If the number of ignition cycles after correcting the previous determination value VJ is less than the predetermined number (NO in S202), a frequency distribution of 90-degree integrated value lpkknk is created using 90-degree integrated value lpkknk. (S206). As a result, median value VMED, standard deviation σ, BGL, and knock determination level VKD are set.

  If the number of ignition cycles since the last correction of determination value VJ is equal to or greater than a predetermined number (YES in S202), determination value VJ is corrected in accordance with knock occupancy KC (S204). .

  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, in an operating state in which the load of engine 100 is low and knocking hardly occurs, for example, during idling, the frequency distribution of 90-degree integrated value lpkknk is a normal distribution as shown in FIG. In this frequency distribution, the standard deviation σ is small. As a result, knock determination level VKD decreases.

  On the other hand, when the load on engine 100 is high, mechanical vibration of engine 100 itself increases. Therefore, even if knocking does not occur, the 90-degree integrated value lpkknk inevitably increases. However, calculation processing in engine ECU 200 requires time. Therefore, a certain amount of time is required for knock determination level VKD to increase following the 90-degree integrated value lpkknk.

  Therefore, when the load is changed from a low state to a high state, such as when the stopped vehicle starts, the number of times that the 90 degree integrated value lpkknk equal to or higher than the knock determination level VKD is increased. If the determination value VJ is corrected in this state, the determination value VJ is erroneously reduced even if knocking has not occurred.

  Knock strength N is calculated by dividing 90-degree integrated value lpkknk by BGL. BGL is calculated by subtracting the standard deviation σ from the median value VMED. Therefore, when the standard deviation σ temporarily increases when the load changes from a low state to a high state, the knock strength N can be increased even if knocking does not occur.

  In either case, the ignition timing can be retarded unnecessarily. Therefore, when knock intensity N is smaller than the minimum guard value (YES in S112), knock determination, ignition timing control, and knock occupancy KC count are stopped (S114).

  Thus, until the magnitude of vibration detected in engine 100 becomes sufficiently large, knocking determination, ignition timing control, and knock occupancy KC counting can be stopped. Therefore, when the load of engine 100 changes from a low state to a high state, determination value VJ can be prevented from being erroneously corrected, and ignition timing can be prevented from being retarded erroneously. As a result, the ignition timing can be accurately controlled.

  As described above, in the ignition timing control apparatus according to the present embodiment, when the knock magnitude N calculated by dividing the intensity 90 integrated value lpkknk by BGL is smaller than the minimum guard value, the determination of knocking, ignition Timing control and counting of knock occupancy KC for correcting determination value VJ are stopped. Thereby, the determination of knocking, the control of the ignition timing, and the counting of the knock occupancy KC can be stopped until the intensity of vibration detected in the engine becomes sufficiently large. Therefore, when the engine load changes from a low state to a high state, it is possible to prevent the determination value VJ from being erroneously corrected and the ignition timing from being erroneously retarded. As a result, the ignition timing can be accurately controlled.

  Instead of stopping knocking determination, ignition timing control, and knock occupancy rate KC counting when knock intensity N is smaller than the minimum guard value, knocking is detected when 90-degree integrated value lpkknk is smaller than the minimum guard value. Determination, ignition timing control, and knock occupancy KC counting may be stopped.

  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 FIG. (1) which shows the 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. FIG. 10 is a diagram (part 2) illustrating a frequency distribution of a 90-degree integrated value lpkknk.

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 Band pass 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 704 calculating unit 706 knock determination level calculation unit, 708 counting unit, 710 correction unit 800 stops.

Claims (8)

Means for detecting the intensity of vibration of the internal combustion engine in a plurality of ignition cycles;
Calculating means for calculating a first value by subtracting a product of the standard deviation of the intensity and a first coefficient from the median value of the intensity ;
Means for calculating a second value by dividing the intensity by the first value;
Control means for controlling the ignition timing of the internal combustion engine according to a result of comparing the second value and the first determination value;
Setting means for setting a second determination value by adding the product of the standard deviation of the intensity and the second coefficient to the median value of the intensity ;
Means for counting the frequency at which an intensity equal to or greater than the second determination value is detected;
Correction means for correcting the first determination value according to the frequency at which the intensity equal to or higher than the second determination value is detected;
If the previous SL second value is smaller than a predetermined threshold value, and a stop means for stopping at least one of the count of control and frequency of the ignition timing, the ignition timing control for an internal combustion engine apparatus. Said stop means, if the previous SL second value is smaller than the threshold value, comprising means for stopping both the control and frequency counts of the ignition timing, the ignition timing of the internal combustion engine according to claim 1 Control device. The ignition timing control device for an internal combustion engine according to claim 1 or 2 , wherein the control means includes means for retarding the ignition timing when the second value is larger than the first determination value. The correction means includes
Means for correcting the first determination value to be smaller when the frequency at which the intensity equal to or greater than the second determination value is detected is greater than a predetermined frequency;
And means for correcting so that the first determination value when frequency of the second judgment value or more intensity is detected is smaller than the frequency of said predetermined increase, to claim 3 An ignition timing control device for an internal combustion engine as described. Detecting the intensity of vibration of the internal combustion engine in a plurality of ignition cycles;
Calculating a first value by subtracting a product of the standard deviation of the intensity and a first coefficient from the median value of the intensity ;
Calculating a second value by dividing the intensity by the first value;
Controlling the ignition timing of the internal combustion engine according to a result of comparing the second value and the first determination value;
Setting a second determination value by adding a product of the standard deviation of the intensity and a second coefficient to the median value of the intensity ;
Counting the frequency at which an intensity equal to or greater than the second determination value is detected;
Correcting the first determination value according to the frequency with which the intensity equal to or higher than the second determination value is detected;
If the previous SL second value is smaller than a predetermined threshold value, and a step of stopping the at least one of the count of control and frequency of the ignition timing, the ignition timing control method for an internal combustion engine. Step stopping the at least one may be pre SL when the second value is smaller than the threshold value, stop both the count of control and frequency of the ignition timing of the count of control and frequency of the ignition timing The ignition timing control method for an internal combustion engine according to claim 5 , comprising: Controlling the ignition timing of the internal combustion engine, when the second value is greater than the first determination value, comprising the step of retarding the ignition timing, the internal combustion engine according to claim 5 or 6 Ignition timing control method. The step of correcting the first determination value includes:
Correcting the first determination value to be smaller when the frequency at which the intensity equal to or greater than the second determination value is detected is greater than a predetermined frequency;
And a step of correcting so that the frequency of the second judgment value or more intensity is detected increases said first determination value is smaller than the frequency of said predetermined, according to claim 7 An ignition timing control method for an internal combustion engine.

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