JP4992688B2 - 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 Laid-Open No. 2007-255195 (Patent Document 1) discloses a detection unit for detecting the intensity of vibration generated in an internal combustion engine a plurality of times, and vibration caused by knocking according to each intensity detected by the detection unit. And a control unit for controlling the ignition timing of the internal combustion engine based on a result of comparing the knock intensity with a predetermined first determination value. A second calculation unit for calculating the median value and standard deviation of the intensity detected by the detection unit, and a second calculation unit that is calculated by adding the product of the standard deviation and a predetermined coefficient to the median value An internal combustion engine that includes a second correction unit for correcting the first determination value so that the degree to which the ignition timing is retarded by the control unit is increased when the determination value is larger than the first determination value. Open engine ignition timing control device .

According to the ignition timing control device described in this publication, the intensity of vibration generated in the internal combustion engine is detected a plurality of times. In accordance with each detected intensity, a knock intensity relating to the intensity of vibration caused by knocking is calculated. 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, when the knock magnitude is larger than the determination value, the ignition timing is retarded, and when the knock intensity is smaller than the determination value, the ignition timing is advanced. When the second determination value calculated by adding the product of the standard deviation and a predetermined coefficient to the median is larger than the first determination value, the degree to which the ignition timing is retarded by the control unit increases. As described above, the first determination value is corrected. Thereby, in a state where it can be said that knocking frequently occurs, it is possible to suppress the determination value compared with the vibration intensity from being excessive with respect to the vibration generated in the internal combustion engine. Therefore, it is possible to easily retard the ignition timing. As a result, the occurrence of knocking can be suppressed.
JP 2007-255195 A

  By the way, in an internal combustion engine, noise such as vibration generated when an intake valve or an exhaust valve is closed, vibration due to a fuel pump (in particular, a high pressure fuel pump of a direct injection injector) is generated. In an internal combustion engine provided with a plurality of cylinders, a cylinder in which noise is superimposed and a cylinder in which noise is not superimposed may be mixed. Therefore, the detected intensity can include the intensity of the cylinder where noise is superimposed and the intensity of the cylinder where noise is not superimposed. Therefore, when the determination value is set based on the detected median value and standard deviation, the determination value may be erroneously set due to the influence of noise. In this case, the controllability of the ignition timing can be deteriorated. However, Japanese Patent Laid-Open No. 2007-255195 does not disclose or suggest such a problem.

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

  An internal combustion engine ignition timing control device according to a first aspect of the present invention is an internal combustion engine ignition timing control device provided with a plurality of cylinders. The ignition timing control device compares the detected intensity and the first determination value with detection means for detecting the intensity of vibration of the internal combustion engine corrected for each cylinder in a plurality of ignition cycles for each cylinder. Control means for controlling the ignition timing of the internal combustion engine according to the result, setting means for setting a second determination value according to the intensity detected in the plurality of cylinders, and a second determination value or more Means for counting the frequency at which the intensity is detected and 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. 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 first aspect of the invention.

  According to this configuration, the vibration intensity of the internal combustion engine is detected in a plurality of ignition cycles for each cylinder. The ignition timing of the internal combustion engine is controlled according to the result of comparing the intensity of vibration of the internal combustion engine and the first determination value. The first determination value is corrected according to the frequency with which the intensity equal to or higher than the second determination value is detected. The second determination value is set according to the intensity detected in the plurality of cylinders. The intensity of vibration of the internal combustion engine corrected for each cylinder is detected. For example, the correction is made so that the strength of the cylinder on which the noise is superimposed is reduced and the strength of the cylinder on which the noise is not superimposed is increased. Thereby, the difference between the strength of the cylinder where noise is superimposed and the strength of the cylinder where noise is not superimposed can be reduced. Therefore, the influence of noise on the second determination value can be reduced. Based on such a second determination value, the first determination value used for controlling the ignition timing is corrected. 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 improve the controllability of the ignition timing.

  In the internal combustion engine ignition timing control apparatus according to the second aspect of the invention, in addition to the configuration of the first aspect of the invention, the detection means is an internal combustion engine that is corrected so as to be small in at least any one of the plurality of cylinders. Means for detecting the intensity of vibration of the engine. 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 second aspect.

  According to this configuration, correction is made so that the vibration intensity of the internal combustion engine is reduced in at least one of the plurality of cylinders. Thereby, for example, correction can be made so that the strength of the cylinder on which noise is superimposed is reduced. Therefore, the difference between the strength of the cylinder where noise is superimposed and the strength of the cylinder where noise is not superimposed can be reduced. As a result, the influence of noise on the second determination value used for correcting the first determination value can be reduced.

  In the internal combustion engine ignition timing control apparatus according to the third aspect of the invention, in addition to the configuration of the first aspect of the invention, the detection means is an internal combustion engine that has been corrected so as to increase in at least one of the plurality of cylinders. Means for detecting the intensity of vibration of the engine. 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 third aspect of the invention.

  According to this configuration, correction is made so that the vibration intensity of the internal combustion engine is increased in at least one of the plurality of cylinders. Thereby, for example, it is possible to correct the cylinder so that the strength of the cylinder on which no noise is superimposed is increased. Therefore, the difference between the strength of the cylinder where noise is superimposed and the strength of the cylinder where noise is not superimposed can be reduced. As a result, the influence of noise on the second determination value used for correcting the first determination value can be reduced.

  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, when the detected intensity is larger than the first determination value, Means for retarding. The correcting means includes means for correcting the first determination value to be smaller when the frequency at which the intensity equal to or higher than the second determination value is detected is higher than a predetermined frequency. An internal combustion engine ignition timing control method according to an eleventh aspect of the invention has the same requirements as the internal combustion engine ignition timing control apparatus according to the fourth aspect of the invention.

  According to this configuration, when the detected intensity is greater than the first determination value, the ignition timing is retarded. Thereby, when knocking occurs, the ignition timing can be retarded. 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 decreased. This makes it easy to retard the ignition timing when knocking occurs frequently. Therefore, the frequency with which knocking occurs can be reduced.

  An ignition timing control device for an internal combustion engine according to a fifth aspect of the invention includes, in addition to the configuration of any one of the first to fourth aspects, means for calculating an average value of the intensity detected in a plurality of cylinders, and an average value The means for calculating the first value representing the median value of the detected intensity is updated by updating with a smaller update amount as the value is larger, and the detection is performed by updating with a smaller update amount as the average value is larger. Means for calculating a second value representative of the standard deviation of the measured intensity. The setting means includes means for setting the second determination value by adding the product of the coefficient greater than zero and the second value to the first value. An internal combustion engine ignition timing control method according to a twelfth 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 average value of the intensity detected in the plurality of cylinders is calculated. By updating with a smaller update amount as the average value is larger, a first value representing the median value of the detected intensity and a second value representing the standard deviation of the detected intensity are calculated. The second determination value is set by adding the product of the coefficient greater than zero and the second value to the first value. In the ignition timing control device for an internal combustion engine using the second determination value, the controllability of the ignition timing can be improved.

  An ignition timing control device for an internal combustion engine according to a sixth aspect of the present invention includes, in addition to the configuration of any one of the first to fourth aspects, means for calculating an average value of the intensity detected in a plurality of cylinders, And means for calculating a first value representing the median value of the intensity and means for calculating a second value representing the standard deviation of the detected intensity. The setting means includes a means for setting the second determination value by adding the product of the coefficient greater than zero and the second value to the first value, and a smaller correction amount as the average value increases. Means for correcting the determination value of 2. An ignition timing control method for an internal combustion engine according to a thirteenth invention has the same requirements as the ignition timing control device for an internal combustion engine according to the sixth invention.

  According to this configuration, the average value of the detected intensity in the plurality of cylinders, the first value indicating the median value of the detected intensity, and the second value indicating the standard deviation of the detected intensity are calculated. The second determination value is set by adding the product of the coefficient greater than zero and the second value to the first value. The second determination value is corrected with a smaller correction amount as the average value is larger. In the ignition timing control device for an internal combustion engine using the second determination value, the controllability of the ignition timing can be improved.

  An ignition timing control device for an internal combustion engine according to a seventh aspect of the invention includes, in addition to the configuration of any one of the first to fourth aspects of the invention, means for calculating an average value of the intensities detected in a plurality of cylinders, In order to calculate the first value representing the median value of the detected intensity by determining an update amount that increases as the intensity increases and decreases as the average value increases and updates without limiting the update amount And an update amount that increases as the detected intensity increases and decreases as the average value increases, and updates the update amount by limiting the update amount to a predetermined limit value or less. Means for calculating a second value representing the standard deviation. The setting means includes means for setting the second determination value by adding the product of the coefficient greater than zero and the second value to the first value.

  According to this configuration, the average value of the intensity detected in the plurality of cylinders is calculated. By updating with a smaller update amount as the average value is larger, a first value representing the median value of the detected intensity and a second value representing the standard deviation of the detected intensity are calculated. The second determination value is set by adding the product of the coefficient greater than zero and the second value to the first value. The update amount of the first value is determined so as to increase as the detected intensity increases. The update amount of the first value is not limited. The update amount of the second value is determined so as to increase as the detected intensity increases. The update amount of the second value is limited to a predetermined limit value or less. As a result, it is possible to quickly follow the detected intensity via the first value and to obtain the second determination value in which the variation amount due to the second value is limited. Therefore, it is possible to obtain the second determination value that accurately corresponds to the intensity actually generated in the internal combustion engine. Based on such a second determination value, the first determination value used for controlling the ignition timing is corrected. As a result, the controllability of the ignition timing can be improved.

  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. BGL is a value obtained by subtracting the product of the standard deviation sgm and a coefficient (for example, “1”) from the median value vmed in a 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 When calculating knock magnitude N, BGL is used after inverse logarithmic transformation. 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. That knock magnitude N is equal to or greater than determination value VJ is the same as that 90-degree integrated value lpkknk is equal to or greater than the product of determination value VJ and BGL.

  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 intensity detector 602 detects the intensity corrected for each cylinder in a plurality of ignition cycles for each cylinder. The intensity of vibration is corrected for each cylinder so as to reduce the difference between the cylinders. In the present embodiment, the intensity corrected by a predetermined correction amount is detected so that the intensity of the cylinder on which noise is superimposed is reduced. That is, the intensity corrected to be small in at least any one of the plurality of cylinders is detected. Further, an intensity corrected by a predetermined correction amount is detected so that the intensity of the cylinder to which no noise is superimposed is increased. That is, the intensity corrected so as to increase in at least one of the plurality of cylinders is detected. It should be noted that the cylinder in which the noise is superimposed and the cylinder in which the noise is not superimposed can be determined from the ignition order of the cylinder, the fuel injection timing, and the like as a result of experiment or simulation.

  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 vibration waveform is detected for each cylinder.

  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 correlation coefficient K is calculated for each cylinder.

  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. The 90-degree integrated value lpkknk is calculated for each cylinder.

  Calculation unit 610 calculates knock magnitude N using 90-degree integrated value lpkknk. Knock strength N is calculated for each cylinder. Determination unit 612 determines whether or not knocking has occurred for each ignition using correlation coefficient K and knock magnitude N. 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.

  The ignition timing control unit 614 performs control by correcting the ignition timing according to whether knocking has occurred. The ignition timing is controlled for each cylinder. 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 for each cylinder. The determination value setting unit 700 includes a vkd calculation unit 702, a vkd correction unit 704, an average value calculation unit 706, a median value calculation unit 710, a standard deviation calculation unit 720, a count unit 730, and a determination value correction unit 732. With.

  The vkd calculation unit 702 calculates a knock determination level vkd. As shown in FIG. 11, knock determination level vkd is calculated for each cylinder using the frequency distribution of 90 ° 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. The frequency distribution is created for each cylinder.

  In the frequency distribution, as shown in FIG. 11, the median value vmed and standard deviation sgm of 90-degree integrated value lpkknk are calculated for each cylinder. Further, knock determination level vkd is calculated using median value vmed and standard deviation sgm.

  In the present embodiment, median vmed and standard deviation sgm approximated to median and standard deviation calculated based on a plurality of (for example, 200 ignition cycles) 90-degree integrated values lpkknk are calculated for each ignition cycle. Is done. Therefore, median value vmed and standard deviation sgm calculated in the present embodiment may be different from the actual median value and standard deviation.

  As shown in FIG. 11, a value obtained by adding the product of the coefficient U (U is a constant, for example, U = 3) and the standard deviation sgm to the median value vmed is calculated as the knock determination level vkd. The coefficient U is a coefficient obtained from data or knowledge obtained through experiments or the like. A value other than “3” may be used as the coefficient U.

  The vkd correction unit 704 corrects the knock determination level vkd by adding the update amount dv to the knock determination level vkd. Therefore, knock determination level vkd is expressed by the following equation (3).

vkd [i] = vmed [i] + U × sgm [i] + dv… (3)
[I] in equation (3) indicates that this is the current value.

The update amount dv is calculated using the following equation (4).
dv = abs (lpkknk [i-1] -vmed [i]) / C… (4)
[I-1] in equation (4) indicates the previous value. “Abs (lpkknk [i-1] -vmed [i])” indicates the absolute value of lpkknk [i-1] -vmed [i]. In Expression (4), “C” is a constant (for example, “4”).

  From equations (3) and (4), knock determination level vkd is expressed by equation (5) below.

vkd [i] = vmed [i] + U × sgm [i] + abs (lpkknk [i-1] -vmed [i]) / C… (5)
When calculating the knock determination level vkd, the update amount dv is limited to the upper guard value verm or less. Further, the update amount dv is limited to a lower limit guard value min (for example, “1”) or more. That is, the update amount dv is represented by the following inequality.

min ≦ dv ≦ verm [i-1]… (6)
The upper guard value verm is calculated using the following equation (7).

verm [i-1] = verm [i-2] + (lpkknk [i-1] -vmall [i-1] -verm [i-2]) / D… (7)
In Expression (7), “D” is a constant (for example, “16”). “Vmall” is an average value of 90 degree integrated values lpkknk detected in a plurality of cylinders (all cylinders). [I-2] indicates that the previous value is further the previous value.

  The average value calculation unit 706 calculates an average value vmall. The average value vall is calculated using the following equation (8).

vmall [i-1] = vmall [i-2] + (lpkknk [i-1] -vmall [i-2]) / tKNMS… (8)
“TKNMS” in Expression (8) is a value determined according to the upper guard value verm. The tKNMS is set so as to decrease as the upper guard value verm increases, that is, increase as the upper guard value verm decreases.

Median value calculation unit 710 calculates median value vmed using equation (9) below.
vmed [i] = vmall [i-1] + dvm [i]… (9)
“Dvm” in Equation (9) is a correction value.

  The correction value dvm is calculated by adding the update amount dv to the previous value. Therefore, the correction value dvm is expressed by the following equation (10).

dvm [i] = dvm [i-1] + dv… (10)
As is clear from the equations (8) to (10), the median value vmed is represented by the following equation (11).

vmed [i] = vmall [i-2] + (lpkknk [i-1] -vmall [i-2]) / tKNMS + dvm [i-1] + dv… (11)
Equation (4) and Formula (11) As it is clear from, in this embodiment, by updating the larger the detected 90-degrees integrated value lpkknk large listening update amount, median vmed calculated . Further, when the median value vmed is calculated, the update amount dv is not limited. Accordingly, in this embodiment, defines the detected 90-degrees integrated value update amount lpkknk is ing larger as larger, and by updating without limiting update amount, the median vmed is calculated.

  The standard deviation calculation unit 720 calculates a standard deviation sgm. The standard deviation sgm is calculated by adding the update amount dv to the previous value of the standard deviation sgm. Therefore, the standard deviation sgm is expressed by the following equation (12).

sgm [i] = sgm [i-1] + dv… (12)
Equation (4) and it is clear from (12), in this embodiment, by updating the larger the detected 90-degrees integrated value lpkknk large heard updating amount, the standard deviation sgm is calculated . Further, when calculating the standard deviation sgm, the update amount dv is limited to the upper guard value verm or less and the lower guard value min or more.

Accordingly, in the present embodiment, the detected 90-degrees integrated value lpkknk determine the update amount as large ing large, and by updating by limiting the amount of update, the standard deviation sgm is calculated.

  Counting unit 730 counts the frequency (ratio) of 90-degree integrated value lpkknk equal to or higher than knock determination level vkd as a knock occupancy KC for each cylinder.

  The determination value correction unit 732 corrects the determination value VJ for each cylinder. 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).

  A control structure of a program executed by engine ECU 200 will be described with reference to FIGS. Note that the program described below is repeatedly executed, for example, every ignition cycle. That is, the program described below is executed in a plurality of ignition cycles.

  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 for each cylinder based on the signal transmitted from knock sensor 300, corresponding to the crank angle. The intensity corrected so that the intensity of the cylinder on which noise is superimposed is reduced and the intensity of the cylinder on which noise is not superimposed is increased is detected.

  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, 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 S210.

  In S204, determination value VJ is corrected 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 S210, engine ECU 200 calculates an average value vmall of 90-degree integrated value lpkknk.

  In S212, engine ECU 200 calculates median value vmed and standard deviation sgm. In S214, engine ECU 200 calculates knock determination level vkd. In S216, engine ECU 200 corrects knock determination level vkd. Thereafter, the process returns to S100.

  Note that the order in which the processes of S100 to S216 are performed is not limited to the order shown in FIGS. You may make it perform the process of S100-S216 in the order different from the order shown in FIG. 12 and FIG.

  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, in order to correct determination value VJ, the frequency of 90-degree integrated value lpkknk equal to or higher than knock determination level vkd is counted as knock occupancy KC (S200).

  If the number of ignition cycles after correcting previous 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.

  Further, an average value vmall of the 90-degree integrated value lpkknk is calculated (S210). The median value vmed and standard deviation sgm of the 90-degree integrated value lpkknk are calculated (S212). Knock determination level vkd is calculated using median value vmed and standard deviation sgm (S214). Further, knock determination level vkd is corrected (S216).

By the way , since the 90-degree integrated value lpkknk detected in the cylinder in which noise is superimposed is large, the knock determination level vkd is difficult to be updated when the average value vmall increases. Therefore, knock determination level vkd can be unnecessarily reduced. In this case, the knock occupancy KC can increase by mistake. Therefore, eventually, the ignition timing can be delayed by mistake.

  Therefore, in the present embodiment, the intensity of vibration of engine 100 corrected so that the intensity of the cylinder where noise is superimposed is reduced and the intensity of the cylinder where noise is not superimposed is increased is detected. Thereby, the difference between the strength of the cylinder where noise is superimposed and the strength of the cylinder where noise is not superimposed can be reduced. Therefore, the influence of noise can be reduced so that the average value vmall does not increase. As a result, the knock determination level vkd can be increased to a value that can appropriately control the ignition timing.

  In the present embodiment, the median value vmed is calculated by determining an update amount that increases as the detected 90-degree integrated value lpkknk increases, and updating without limiting the update amount. Also, the standard deviation sgm is calculated by determining an update amount that increases as the detected 90-degree integrated value lpkknk increases, and updating the update amount so as to be less than or equal to the upper limit guard value.

  As a result, it is possible to quickly follow the detected intensity via the median value vmed, and obtain the knock determination level vkd in which the variation amount due to the standard deviation sgm is limited. Therefore, it is possible to obtain a knock determination level vkd that accurately corresponds to the intensity actually generated in the internal combustion engine. Based on the knock determination level vkd, the determination value VJ used for controlling the ignition timing is corrected. As a result, the controllability of the ignition timing can be improved.

  As described above, according to the ignition timing control apparatus according to the present embodiment, the ignition timing of the engine is determined according to the result of comparing the knock magnitude N calculated using the magnitude of the engine vibration and the determination value VJ. Be controlled. The determination value VJ is corrected according to the frequency at which an intensity equal to or higher than the knock determination level vkd is detected. Knock determination level vkd is set according to the intensity detected in a plurality of cylinders. The intensity of engine vibration corrected for each cylinder is detected. Thereby, the difference between the strength of the cylinder where noise is superimposed and the strength of the cylinder where noise is not superimposed can be reduced. Therefore, the influence of noise on the knock determination level vkd can be reduced. Based on the knock determination level vkd, the determination value VJ used for controlling the ignition timing is corrected. As a result, the controllability of the ignition timing can be improved.

  Instead of the 90-degree integrated value lpkknk, the maximum intensity lvpk in the vibration waveform may be used as shown in FIG.

  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 the largest intensity | strength lvpk in a vibration waveform.

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 vkd calculator, 704 vkd correction unit, the average value calculating unit 706, 710 a central value calculating section, 720 a standard deviation calculator, 730 counting unit, 732 determination value correction unit.

Claims (12)

An ignition timing control device for an internal combustion engine provided with a plurality of cylinders,
Detecting means for detecting the intensity of vibration of the internal combustion engine corrected for each cylinder in a plurality of ignition cycles for each cylinder;
Control means for retarding the ignition timing when the detected intensity is greater than the first determination value;
Setting means for setting a second determination value according to the intensity detected in the plurality of cylinders;
Means for counting the frequency at which an intensity equal to or greater than the second determination value is detected;
Ignition of an internal combustion engine, comprising: correction 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. Timing control device.   2. The internal combustion engine according to claim 1, wherein the detection unit includes a unit for detecting a vibration intensity of the internal combustion engine corrected to be small in at least one of the plurality of cylinders. Ignition timing control device.   2. The internal combustion engine according to claim 1, wherein the detection means includes means for detecting a vibration intensity of the internal combustion engine corrected to be large in at least one of the plurality of cylinders. Ignition timing control device. Means for calculating an average value of detected intensities in a plurality of cylinders;
A calculation means for calculating a first value representing a median value of the detected intensity by determining an update amount that increases as the detected intensity increases and updating without limiting the update amount ;
Means for calculating a second value representing a standard deviation of the detected intensity by determining an update amount that increases as the detected intensity increases, and updating the update quantity by limiting the update amount to the limit value or less. And further comprising
It said setting means includes means for setting said second judgment value by adding the product of the zero coefficient larger than the second value to the first value, of claim 1-3 The ignition timing control device for an internal combustion engine according to any one of the above. Before Symbol setting means, in addition to the product of the second value and the coefficient, the addition increases as the detected intensity is large, and the update amount is limited to below the limit value to the first value The ignition timing control device for an internal combustion engine according to claim 4 , further comprising means for setting the second determination value. The calculation means uses a value determined to be larger as the detected intensity is larger and smaller as the average value is larger and the update amount, and updating without limiting the update amount , comprising said first hand stage for calculating the value, the ignition timing control apparatus for an internal combustion engine according to claim 4 or 5. An ignition timing control method for an internal combustion engine provided with a plurality of cylinders,
Detecting the intensity of vibration of the internal combustion engine corrected for each cylinder in a plurality of ignition cycles for each cylinder;
If the detected intensity is greater than the first determination value, retarding the ignition timing ;
Setting a second determination value according to the intensity detected in the plurality of cylinders;
Counting the frequency at which an intensity equal to or greater than the second determination value is detected;
An ignition timing control method for an internal combustion engine , comprising: correcting so that the first determination value is decreased when the frequency at which the intensity equal to or greater than the second determination value is detected is greater than a predetermined frequency. . Detecting the intensity of the internal combustion engine, comprising the steps of detecting a magnitude of vibration of the corrected the internal combustion engine so as to be smaller in at least one of the cylinders of the plurality of cylinders, in claim 7 An ignition timing control method for an internal combustion engine as described. Detecting the intensity of the internal combustion engine, comprising the steps of detecting a magnitude of vibration of the corrected the internal combustion engine so as to be larger in at least one of the cylinders of the plurality of cylinders, in claim 7 An ignition timing control method for an internal combustion engine as described. Calculating an average value of intensity detected in a plurality of cylinders;
Setting a limit value to be smaller as the average value is larger;
Calculating a first value representing a median value of detected intensities by determining an update amount that increases as the detected intensity increases and updating without limiting the update amount ;
A step of calculating a second value representing a standard deviation of the detected intensity by determining an update amount that increases as the detected intensity increases, and updating the update quantity to be limited to the limit value or less. In addition,
The step of setting the second determination value includes the step of setting the second determination value by adding a product of a coefficient greater than zero and the second value to the first value. Item 10. The ignition timing control method for an internal combustion engine according to any one of Items 7 to 9 . Before Symbol setting a second determination value, in addition to the product of the second value and the coefficient increases as the detected intensity is large, and the update amount is limited to below the limit value Setting the second determination value by adding to the first value;
The ignition timing control method for an internal combustion engine according to claim 10 , further comprising a step of correcting the second determination value with a smaller correction amount as the average value is larger. The step of calculating the first value uses a value determined so as to increase as the detected intensity increases and decreases as the average value increases and the update amount, and does not limit the update amount. by updating the said including first steps of calculating the value, the ignition timing control method for an internal combustion engine according to claim 10 or 11.

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