JP2010281262A - Knock determining device for internal combustion engine, and knocking control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase accuracy in knock determination based on vibration intensity detected by a knock sensor and the waveform of the vibration intensity. <P>SOLUTION: The vibration intensity detected by the knock sensor is weighted by a weighting coefficient Kcn(f) set for each cylinder and each narrow frequency band based on an engine revolving speed NE, and then knock determining vibration intensity is calculated (S106-S112). A correlation coefficient K between the knock intensity N and the waveform analysis of vibration is calculated based on the vibration intensity (S116-S118), and used for knock determination. The vibration intensity is therefore obtained which leads to adequate knock determination corresponding to a vibration state difference between cylinders relative to the knock sensor, a vibration state difference between frequency bands, and the influences of the engine revolving speed NE on the differences, thus enabling knock determination with higher accuracy. Aside from this, wide band determination and narrow band determination are both executed in determining the waveform of the vibration intensity to adequately distinguish the waveform of noise from the waveform of actual knocking vibration, thus enabling knock determination with higher accuracy. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an internal combustion engine knock determination device that makes a knock determination based on a vibration intensity and a vibration strength waveform detected by a knock sensor provided in an internal combustion engine having a plurality of cylinders, and an internal combustion engine using the internal combustion engine knock determination device The present invention relates to a knocking control device.

  In order to detect vibration caused by knocking with high accuracy in distinction from noise, there is known an apparatus for determining knock based on the vibration intensity waveform together with the vibration intensity detected by a knock sensor (see, for example, Patent Documents 1 to 3). ).

  Devices that detect knocking based on vibration intensity detected by a knock sensor are known (see, for example, Patent Documents 4 to 6).

JP 2007-327367 A (page 8-10, FIG. 7-10) JP 2008-96279 A (page 6-8, FIG. 4) JP 2008-95602 A (page 6-8, FIG. 2) JP 04-65638 A (page 5-6, FIG. 5) Japanese Patent Laid-Open No. 06-200859 (page 6-7, FIG. 1-2) JP-A-10-205386 (page 3-4, FIG. 5)

  When the noise is superimposed on the detection value of the knock sensor, it is easy to erroneously detect whether or not knocking has occurred if the knock determination is made based only on the vibration intensity. For this reason, in Patent Documents 1 to 3, a correlation is obtained by comparing an actual vibration intensity waveform with a knocking waveform model, and knock determination is made based on both the vibration intensity and the correlation.

  However, even when comparing vibration intensity waveforms, the waveform itself may increase the correlation with the knocking waveform model due to noise, and even when knocking is determined based on the waveform along with the vibration intensity, the determination accuracy can be further improved. It is desired.

  Further, when the correlation is determined as described above, the influence of the vibration intensity on the detection value of the knock sensor differs for each cylinder depending on the positional relationship between the cylinder and the knock sensor. In Patent Documents 4 to 6, the vibration level for knock determination or the determination reference value is calculated corresponding to the difference in the distance between the knock sensor and the cylinder, or vibration during combustion and knock vibration By setting the knocking determination reference value for each cylinder according to the ratio to the above, it is possible to compensate for the difference in distance and perform highly accurate knock determination for all the cylinders.

  However, in Patent Documents 4 to 6, the vibration intensity waveform is not taken into account, and the method for improving the determination accuracy in the knock determination including the correlation with the knocking waveform model is unknown.

  An object of the present invention is to improve the accuracy of knock determination performed based on vibration intensity and vibration intensity waveform detected by a knock sensor.

In the following, means for achieving the above-mentioned purpose, and its operation and effect are described.
An internal combustion engine knock determination device according to claim 1 is a knock determination device for determining knock based on vibration intensity and vibration intensity waveform detected by a knock sensor provided in an internal combustion engine having a plurality of cylinders. A plurality of frequency band vibration intensity detecting means for obtaining the vibration intensity detected by the knock sensor for each frequency band, and the vibration intensity obtained by the plurality of frequency band vibration intensity detecting means for all frequency bands. Determination target value calculation means for obtaining a vibration intensity to be the object of the knock determination and a vibration intensity waveform indicating the transition of the vibration intensity, and when the sum is calculated by the determination target value calculation means, based on the situation And weight setting means for setting a weight for the vibration intensity for each cylinder and each frequency band.

  In a multi-cylinder internal combustion engine, the influence of vibration during combustion on the knock sensor differs for each cylinder. Further, even if the cylinders are the same, different effects occur for each frequency band of vibration, and the difference between the frequency bands differs depending on the cylinder.

Therefore, the weight setting unit sets the weight for the vibration intensity for each cylinder and for each frequency band based on the situation at the time of the summation by the determination target value calculation unit.
By combining the weighting for each cylinder and the weighting for each frequency band in this way, the weighting is obtained from the relationship between the cylinder and the frequency band based on the situation, and the vibration strength and vibration strength waveform are obtained by this weighting. Is determined as a knock determination target.

Therefore, the knock determination is performed in consideration of the difference in vibration intensity between the cylinders in addition to the difference in vibration intensity depending on the frequency band.
Thus, the accuracy of knock determination performed based on the vibration intensity and vibration intensity waveform detected by the knock sensor can be improved.

  The internal combustion engine knock determination device according to claim 2, wherein the weight setting unit is configured to determine whether the weight setting unit is a cylinder based on an arrangement relationship between the knock sensor and each cylinder as the situation. A weight is set for the vibration intensity for each and each frequency band.

  Examples of the situation include an arrangement relationship between the knock sensor and each cylinder. Based on this arrangement relationship, weights for vibration intensity are set for each cylinder and each frequency band, so that vibration intensity and vibration intensity waveform can be set. The accuracy of the knock determination performed based on this can be improved.

  The internal combustion engine knock determination apparatus according to claim 3, wherein the weighting setting unit is configured to set the weight setting unit for each cylinder and for each frequency band based on the operating state of the internal combustion engine as the situation. A weight is set for the vibration intensity.

  Examples of the situation include an internal combustion engine operating state. Based on the internal combustion engine operating state, weighting is applied to the vibration intensity for each cylinder and for each frequency band, so that the operation is performed based on the vibration intensity and the vibration intensity waveform. The accuracy of knock determination can be improved.

  5. The internal combustion engine knock determination apparatus according to claim 4, wherein the weighting setting means includes an arrangement relationship between the knock sensor and each cylinder as the situation and an internal combustion engine operating state. Based on the above, weighting is set for the vibration intensity for each cylinder and for each frequency band.

  Examples of the situation include both the positional relationship between the knock sensor and each cylinder and the operating state of the internal combustion engine. Based on this positional relationship and the operating state of the internal combustion engine, the vibration intensity is weighted for each cylinder and each frequency band. By setting, the accuracy of knock determination performed based on the vibration intensity and the vibration intensity waveform can be improved.

  The internal combustion engine knock determination apparatus according to claim 5, wherein the weighting setting means sets the weighting to the vibration intensity by the cylinder as the cylinder is farther from the knock sensor. It is characterized by being enlarged.

  Thus, the weighting is increased as the cylinder is farther from the knock sensor. By setting the weighting according to the arrangement relationship between the cylinder and the knock sensor in this way, the vibration intensity and vibration intensity waveform appropriately reflecting the cylinder position can be obtained together with the difference in the frequency band, so that the knock determination Accuracy can be improved.

  In the internal combustion engine knock determination device according to claim 6, in the internal combustion engine knock determination device according to claim 3 or 4, the weight setting unit corresponds to the difference in operating state of the internal combustion engine toward a lower frequency band side. The difference in weighting is increased.

  In this way, in the low frequency band, the influence of vibration on the knock sensor according to the operating state of the internal combustion engine changes greatly compared to the high frequency band side. For this reason, when the weighting is set according to the operating state of the internal combustion engine, the difference in weighting corresponding to the difference in the operating state of the internal combustion engine on the low frequency band side is increased. In this way, by changing the weighting difference corresponding to the difference in influence on the knock sensor depending on the frequency band, it is possible to obtain the vibration intensity and the vibration intensity waveform that appropriately reflect the difference in the frequency band together with the cylinder position. Therefore, knock determination accuracy can be improved.

  The internal combustion engine knock determination device according to claim 7, wherein the weight setting unit corresponds to the difference in the operation state of the internal combustion engine as the cylinder closer to the knock sensor. It is characterized by eliminating or reducing the difference in weighting.

  In the cylinder close to the knock sensor, the influence of vibration at the time of combustion on the knock sensor does not fluctuate greatly due to the difference in the operating state of the internal combustion engine, as compared to the far cylinder. For this reason, the closer the cylinder to the knock sensor, the smaller or less the weighting difference corresponding to the difference in the operating state of the internal combustion engine.

As a result, the accuracy of the knock determination performed based on the vibration intensity and the vibration intensity waveform can be improved.
In the internal combustion engine knock determination device according to claim 8, in the internal combustion engine knock determination device according to claim 3, 4, 6 or 7, as the internal combustion engine operating state, the higher the internal combustion engine speed is in a high rotation region. The weighting for each cylinder by the weighting setting means is the same or close.

  An example of the operating state of the internal combustion engine is the internal combustion engine speed. When the rotational speed of the internal combustion engine is in the high rotation region, the influence of vibration on the knock sensor due to the difference in cylinder is smaller than that in the low rotation region. For this reason, when the weighting is set for each cylinder, the weighting for each cylinder is the same or close in the high rotation region. In this way, by changing the weighting difference between the cylinders in response to the difference in the effect on the knock sensor due to the rotational speed of the internal combustion engine, the vibration intensity and vibration appropriately reflecting the cylinder position as well as the difference in frequency band Since the intensity waveform can be obtained, the knock determination accuracy can be improved.

  In the internal combustion engine knock determination device according to claim 9, in the internal combustion engine knock determination device according to any one of claims 1 to 8, the plurality of frequency bands have a minimum frequency band of 7kHz, and the 7kHz The weighting difference set based on the situation in the band is increased.

  Thus, by setting the 7 kHz band as the lowest frequency band and increasing the difference in weight set based on the situation in this 7 kHz band, it is possible to set the weight according to the difference in influence on the knock sensor. Become. As a result, the vibration intensity and vibration intensity waveform appropriately reflecting the difference between the cylinder position and the frequency band can be obtained, so that the knock determination accuracy can be improved.

  The internal combustion engine knock determination device according to claim 10 is an internal combustion engine knock determination device that performs knock determination based on vibration intensity determination and vibration intensity waveform determination with respect to vibration detected by a knock sensor provided in the internal combustion engine, The vibration intensity waveform determination includes a wideband determination that determines a waveform correlation between a wideband waveform that is a vibration intensity waveform in a wide frequency band in the vibration and a knocking waveform, and a narrow frequency that is a partial band within the wide frequency band. And narrow-band determination for determining a vibration intensity state in the band.

As described above, the determination of the vibration intensity waveform includes not only the wideband determination for determining the waveform correlation between the wideband waveform and the knocking waveform but also the narrowband determination.
Waveform determination using a simple vibration frequency waveform in a wide frequency band is not sufficient as waveform determination. That is, even if the knocking vibration is not large, a vibration intensity waveform similar to the knocking waveform may occur due to noise.

  Therefore, it is necessary to distinguish a waveform similar to the knocking waveform caused by such noise from a waveform in the case of actually knocking vibration. In the case of knocking vibration, a characteristic vibration intensity state appears in a narrow frequency band that is a partial band within the wide frequency band. Therefore, by adding such a narrow band determination together with the wide band determination, it is possible to appropriately distinguish a waveform due to noise and a waveform in the case of actually knocking vibration.

  As a result, the accuracy of the vibration intensity waveform determination can be improved, so that the accuracy of the knock determination performed based on the vibration intensity detected by the knock sensor and the vibration intensity waveform can be improved.

  The internal combustion engine knock determination device according to claim 11, wherein the narrow frequency band has a strong tendency to superimpose vibration due to knocking within the wide frequency band. It is a band.

  In narrow band determination, the accuracy of vibration intensity waveform determination can be further improved by determining the vibration intensity state in a narrow frequency band where vibration due to knocking is particularly strong in a wide frequency band.

  In the internal combustion engine knock determination device according to claim 12, in the internal combustion engine knock determination device according to claim 11, the wide frequency band has a 7 kHz band as a lowest frequency band, and vibration due to knocking is superimposed on the lowest frequency band. It is characterized by a narrow frequency band with a strong tendency.

  Specifically, such a 7 kHz band is a wide frequency band having the lowest frequency band, and a 7 kHz band is a narrow band. At the time of vibration intensity waveform determination, the 7 kHz band can be used as an index to improve the determination accuracy.

  In the internal combustion engine knock determination device according to claim 13, the internal combustion engine knock determination device according to any one of claims 10 to 12, wherein the vibration intensity waveform determination shows a high correlation in the broadband determination. In addition, the condition for knock determination is that a high vibration intensity state is indicated in the narrow band determination.

  In this way, it is possible to easily determine vibration intensity waveform with high accuracy by providing a high correlation with a wide band waveform and a high vibration intensity state in a narrow frequency band. Accuracy can be improved.

  The internal combustion engine knock determination device according to claim 14, wherein the vibration intensity state determined by the narrow band determination is an internal combustion engine combustion. It is an integrated value of vibration intensity in the stroke region.

By using such an integrated value as the vibration intensity state in the narrow frequency band, it is possible to determine the vibration intensity waveform with high accuracy.
The internal combustion engine knock determination device according to claim 15, wherein the vibration intensity state determined by the narrow band determination is an internal combustion engine combustion. It is a peak value of vibration intensity in the stroke region.

  Such a vibration intensity peak value can be used as the vibration intensity state in the narrow frequency band. As a result, accuracy can be maintained to some extent and simple vibration intensity waveform determination can be performed.

  The internal combustion engine knock determination device according to claim 16, wherein the narrow band determination is performed by setting a plurality of narrow frequency bands in the wide frequency band, and knocking the internal combustion engine knock determination device according to claim 14 or 15. When the vibration intensity in the narrow frequency band where vibration due to is easy to be superimposed is larger than the vibration intensity in other narrow frequency bands, it is determined that a high vibration intensity state is indicated. And

  In this way, it is possible to make a judgment by comparing the narrow frequency band where vibration due to knocking is likely to be superimposed with the other narrow frequency band based on the vibration intensity in the vibration intensity state, and it is possible to make a highly accurate and simple vibration intensity waveform determination. Become.

  In the internal combustion engine knock determination device according to claim 17, in the internal combustion engine knock determination device according to claim 14 or 15, in the narrow band determination, a plurality of narrow frequency bands are set in the wide frequency band, If the vibration intensity in two or more narrow frequency bands is larger than the median of the vibration intensity distribution by n (5 ≧ n ≧ 2) times the standard deviation, a high vibration intensity state is indicated. It is characterized by determining.

  When knocking occurs, large vibrations are superimposed on two or more narrow frequency bands. Therefore, the vibration intensity in two or more narrow frequency bands is more standard than the median value of the vibration intensity distribution. When the deviation is larger than n (5 ≧ n ≧ 2) times or more, it may be determined that a high vibration intensity state is indicated.

This can improve the accuracy of vibration intensity waveform determination.
The internal combustion engine knock determination device according to claim 18, wherein in the internal combustion engine knock determination device according to claim 14 or 15, the narrow band determination is performed by setting a plurality of narrow frequency bands within the wide frequency band, and knocking. The vibration intensity in the narrow frequency band in which vibration due to is easy to be superimposed is larger than the vibration intensity in other narrow frequency bands, and the vibration intensity in any two or more narrow frequency bands is If the standard deviation is larger than the median of the vibration intensity distribution by n (5 ≧ n ≧ 2) times or more, it is determined that a high vibration intensity state is indicated.

  By comparing the vibration intensity in the narrow frequency band where vibration due to knocking is likely to be superimposed with other narrow frequency bands, and determining the position based on the position of the vibration intensity distribution, a more accurate vibration intensity waveform can be obtained. Judgment is possible.

  In the internal combustion engine knock determination device according to claim 19, in the internal combustion engine knock determination device according to any one of claims 16 to 18, the vibration intensity in each narrow frequency band is a difference in vibration frequency of the knock sensor. It is characterized by weighting corresponding to the detection characteristics associated with.

  By adjusting the weighting in this way, it is possible to accurately compare the vibration intensities between narrow frequency bands in consideration of the detection characteristics of the knock sensor. Thus, more accurate vibration intensity waveform determination can be performed.

  An internal combustion engine knock determination device according to a twentieth aspect is characterized in that in the internal combustion engine knock determination device according to a nineteenth aspect, the weighting is increased toward a lower frequency side.

Specifically, by doing so, highly accurate vibration intensity can be obtained for each narrow frequency band in correspondence with the detection characteristics of the knock sensor, and highly accurate vibration intensity waveform determination can be performed.
The internal combustion engine knock determination device according to claim 21, wherein the standard deviation is vibration intensity in one narrow frequency band of a plurality of narrow frequency bands. What is calculated based on the distribution is used in all narrow frequency bands.

  The standard deviation is not calculated in all of the two or more narrow frequency bands, but the standard deviation calculated based on the vibration intensity distribution in any one narrow frequency band may be used in all the narrow frequency bands. good. The vibrations generated in the same combustion stroke tend to have similar standard deviations in any narrow frequency band. Accordingly, since it is not necessary to perform standard deviation calculation for each narrow frequency band, it is possible to execute vibration intensity waveform determination quickly and easily without reducing accuracy even if the calculation processing load is reduced.

  The internal combustion engine knocking control device according to claim 22 performs knock determination based on vibration intensity determination and vibration intensity waveform determination for vibration detected by a knock sensor provided in the internal combustion engine, and based on the result of the knock determination. A knock control device for adjusting an ignition timing, wherein the knock determination is performed by the internal combustion engine knock determination device according to any one of claims 1 to 21.

  Thus, in the knocking control device that adjusts the ignition timing based on the result of the knock determination, the knock determination by the internal combustion engine knock determination device according to any one of claims 1 to 21 enables high-accuracy knock determination. This makes it possible to perform knocking control with high accuracy.

4 is a flowchart of knocking control processing executed by the internal combustion engine knock determination device in the first embodiment. The flowchart of an ignition timing feedback control process similarly. FIG. 5 is a diagram illustrating the configuration of a weighting coefficient Kcn (f) map. FIG. 2 is a block diagram of an internal combustion engine control system in the first embodiment. (A)-(c) The graph for demonstrating knock vibration intensity | strength waveform analysis in Embodiment 1. FIG. 10 is a flowchart of knocking control processing according to the second embodiment. The flowchart of an ignition timing feedback control process similarly. 10 is a graph for setting median value VM and standard deviation σ based on vibration intensity frequency distribution in the second embodiment. (A), (b) The graph for demonstrating the weighting coefficient Kw setting in Embodiment 3. FIG.

[Embodiment 1]
1 and 2 are flowcharts of a knocking control process, which is a process as an internal combustion engine knocking determination apparatus of the present invention, and an ignition timing feedback control process related thereto. FIG. 3 is a weighting coefficient Kcn (f) map used in the knocking control process. An electronic control unit (hereinafter referred to as ECU) 4 that controls the internal combustion engine 2 shown in the block diagram of FIG. 4 corresponds to the internal combustion engine knocking control device, and the ECU 4 executes the processes of FIGS. .

  The internal combustion engine 2 shown in FIG. 4 is a port injection spark ignition type in-line four-cylinder gasoline engine mounted on a vehicle for driving the vehicle. FIG. 4 shows only one of the # 1 to # 4 cylinders. It may be an internal combustion engine having another number of cylinders such as 6 cylinders or 8 cylinders, or a V-type internal combustion engine.

  Air is supplied to each combustion chamber 6 of the internal combustion engine 2 through an intake passage 8 including a surge tank 8a and a branch pipe 8b, and from the fuel injection valve 10 provided for each cylinder, An air-fuel mixture is formed by injecting fuel into the fuel cell. This air-fuel mixture is supplied into each combustion chamber 6 of the internal combustion engine 2.

The fuel injection valve 10 may be a direct injection type arranged so as to inject fuel directly into each combustion chamber 6 of the internal combustion engine 2.
As a result, the air-fuel mixture formed in the combustion chamber 6 is ignited by the spark of the spark plug 12 at the ignition timing, so that the air-fuel mixture is combusted, and the piston 14 is pushed down and the crankshaft which is the output shaft 16 is rotated. The air-fuel mixture after combustion is discharged as exhaust from the combustion chamber 6 to the exhaust port 18a, and is discharged to the outside through an exhaust passage 18 having an exhaust purification catalyst and a muffler.

  Here, both the intake valve 20 that opens and closes at the intake port 8c and the exhaust valve 22 that opens and closes at the exhaust port 18a are driven at a constant valve operating angle (or maximum valve lift). The intake valve 20 may be provided with a variable valve timing mechanism so that the valve operating angle (or the maximum valve lift amount) is variable, or the open / close valve timing is advanced or retarded. The exhaust valve 22 may also be configured to advance or retard the opening / closing valve timing.

  The amount of intake air distributed from the intake passage 8 to the combustion chamber 6 of each cylinder is adjusted by the ECU 4 controlling the opening of the throttle valve 26 in accordance with the accelerator operation amount ACCP, which is the depression amount of the accelerator pedal 24. The When the valve operating angle (or maximum valve lift amount) of the intake valve 20 is variable, that is, when a variable valve mechanism is employed, the valve operating angle (or maximum valve lift) of the intake valve 20 is adopted. The amount of intake air distributed to the combustion chamber 6 of each cylinder is adjusted by adjusting the amount). In this case, the throttle valve 26 is normally controlled to be fully opened and the internal combustion engine 2 is operated.

  As described above, the ECU 4 executes ignition timing control and other processes in addition to the fuel injection amount, injection timing, and intake air amount of the internal combustion engine 2. For these processes, the ECU 4 detects signals from the engine speed sensor 28, the cooling water temperature sensor 30, the throttle opening sensor 32, the intake air amount sensor 34, the accelerator operation amount sensor 36, the cam position sensor 38, the knock sensor 40, and the like. Is entered.

  The engine speed sensor 28 is the internal combustion engine speed NE corresponding to the rotation of the crankshaft 16, the coolant temperature sensor 30 is the coolant temperature THW as the internal combustion engine temperature, the throttle opening sensor 32 is the throttle valve opening TA, The intake air amount sensor 34 detects the intake air amount GA, and the accelerator operation amount sensor 36 detects the accelerator operation amount ACCP. Further, the cam position sensor 38 gives the cam angle of the intake cam that drives the intake valve 20, and the knock sensor 40 gives a knock signal (here, voltage signal: V) corresponding to the vibration generated during the combustion stroke of the internal combustion engine 2. Detected by cylinder block. The knock sensor 40 is attached to the cylinder block of the internal combustion engine 2. Here, the knock sensor 40 is attached to the cylinder block at the center position of the in-line four cylinders, that is, the position between the # 2 cylinder and the # 3 cylinder. ~ Vibration during combustion in cylinder # 4 is detected.

  The ECU 4 executes various controls based on these signals, stored data, calculation results, and the like. That is, the ignition timing by the spark plug 12, the fuel injection amount and injection timing by the valve opening control of the fuel injection valve 10, the opening adjustment of the throttle valve 26 described above (if the variable valve mechanism is employed, the intake valve 20 Control such as valve working angle or maximum valve lift adjustment, opening / closing valve timing) is executed. As for the knock signal from the knock sensor 40, the vibration intensity is detected in each narrow frequency band of 7 kHz, 10 kHz, 15 kHz and 20 kHz by the filter processing in the ECU 4, and the wide frequency band between 5 kHz and 20 kHz. But the vibration intensity is detected. In addition, the vibration intensity detection in each narrow frequency band is detected with a bandwidth of ± 2.5 kHz for each frequency. With regard to the wide frequency band, the vibration intensity may be detected by a filter process independent of the narrow frequency band, or may be detected as a combination of vibration intensity in the narrow frequency band.

  Next, the knocking control process of FIG. 1 and the ignition timing feedback control process of FIG. 2 executed by the ECU 4 will be described. The knocking control process (FIG. 1) is a process repeatedly executed at a constant crank angle cycle, and the ignition timing feedback control process (FIG. 2) is a process executed continuously after the knocking control process. The steps in the flowchart corresponding to the individual processing contents are represented by “S˜”.

  When the knocking control process (FIG. 1) is started, it is first determined whether or not the coolant temperature THW is 60 ° C. or higher (S102). If the cooling water temperature THW is less than 60 ° C. after starting (NO in S102), the process proceeds to the ignition timing feedback control process (S120: FIG. 2).

  In the ignition timing feedback control process (FIG. 2), it is first determined whether or not the coolant temperature THW ≧ 60 ° C. (S130). In this case, since the coolant temperature THW <60 ° C. again (NO in S130), the ignition timing is immediately set (S142). Here, the ignition timing learning value stored in the ECU 4 during the previous internal combustion engine operation is used to set the ignition timing corresponding to the current coolant temperature THW. And ignition control is performed based on this ignition timing. Thereafter, as long as the cooling water temperature THW <60 ° C., the above-described processing continues.

  If the coolant temperature THW rises due to continued operation of the internal combustion engine 2 and THW ≧ 60 ° C. (YES in S102), based on the detection results of the engine speed sensor 28 and the cam position sensor 38, It is determined whether any of the cylinders is within a certain crank angle range in the combustion stroke (S104). Here, it is determined whether or not the combustion stroke is within a range of 0 ° to 90 ° CA (° CA represents a crank angle). If the combustion stroke is outside 0 ° to 90 ° CA in any cylinder (NO in S104), the process proceeds to the ignition timing feedback control process (S120: FIG. 2). The process in the state where THW ≧ 60 ° C. in the ignition timing feedback control process (FIG. 2) will be described later.

  If any of the cylinders (represented by “#n cylinder”) is within the combustion stroke of 0 ° to 90 ° CA (YES in S104), it is next determined whether or not the internal combustion engine speed NE exceeds 3000 rpm. (S106).

  If NE ≦ 3000 rpm (NO in S106), a low-rotation weighting coefficient Kcn (f) for the vibration intensity detected by knock sensor 40 during combustion of the #n cylinder is set (S108). The low-rotation weighting coefficient Kcn (f) is as shown in the weighting coefficient Kcn (f) map of FIG.

  In this map, the low-rotation weighting coefficient Kcn (f) is 7 kHz narrow for the # 2 and # 3 cylinders that are adjacent to the knock sensor 40 because the knock sensor 40 is disposed therebetween. Kcn (f) = 0.25 is set in the frequency band, and Kcn (f) = 1 is set in the narrow frequency bands of 10 kHz, 15 kHz, and 20 kHz. For the # 1 and # 4 cylinders that are positioned at both ends of the cylinder block of the internal combustion engine 2 and are not adjacent to the knock sensor 40, Kcn (f) in all narrow frequency bands (7 kHz, 10 kHz, 15 kHz, 20 kHz) ) = 1.

  If NE> 3000 rpm (YES in S106), a high-rotation weighting coefficient Kcn (f) for the vibration intensity detected by knock sensor 40 during combustion of the #n cylinder is set (S110). The high-rotation weighting coefficient Kcn (f) is as shown in the weighting coefficient Kcn (f) map of FIG.

  Since the difference in vibration intensity is small in all cylinders at high rotation, the high rotation weighting coefficient Kcn (f) is Kcn (n) in the narrow frequency band of 7 kHz for all cylinders regardless of whether or not they are adjacent to the knock sensor 40. f) = 0.25, and Kcn (f) = 1 is set in each narrow frequency band of 10 kHz, 15 kHz, and 20 kHz.

  This is because the difference in transmission strength between the cylinders (# 1, # 4) at the end of the cylinder block and the central cylinders (# 2, # 3) becomes large at low revolutions. This means that there is a difference between the cylinders as described above with respect to the weighting coefficient Kcn (f).

  Thus, based on the situation, weights are set for each cylinder and each frequency band based on the positional relationship between the knock sensor 40 and each cylinder and the operating state of the internal combustion engine (in this case, the internal combustion engine speed NE). Yes.

When the weighting coefficient Kcn (f) is set in step S108 or step S110, next, calculation and accumulation of all narrow frequency band summed data are executed (S112).
That is, the vibration intensity of each narrow frequency band (7 kHz, 10 kHz, 15 kHz, 20 kHz) is detected, and the vibration intensity for each narrow frequency band is weighted using the above-described weighting coefficient Kcn (f), and then the entire narrow frequency band. Are summed up every 5 ° CA and the sum is accumulated.

For example, in the case of the # 1 cylinder and the # 4 cylinder, the vibration intensity Nd (5 ° CA) is calculated according to Equation 1 every 5 ° CA when NE ≦ 3000 rpm.
[Formula 1] Nd ← 1 × 7 kHz band vibration strength + 1 × 10 kHz band vibration strength
+ 1 × 15 kHz band vibration intensity + 1 × 20 kHz band vibration intensity When NE> 3000 rpm, the vibration intensity Nd (5 ° CA) is calculated according to Equation 2 every 5 ° CA.

[Formula 2] Nd ← 0.25 × 7 kHz band vibration strength + 1 × 10 kHz band vibration strength
+ 1 × 15 kHz band vibration strength + 1 × 20 kHz band vibration strength In the case of the # 2 cylinder and the # 3 cylinder, the vibration strength Nd (5 ° CA) is calculated according to Equation 3 every 5 ° CA when NE ≦ 3000 rpm.

[Formula 3] Nd ← 0.25 × 7 kHz band vibration strength + 1 × 10 kHz band vibration strength
+ 1 × 15 kHz band vibration intensity + 1 × 20 kHz band vibration intensity When NE> 3000 rpm, the vibration intensity Nd (5 ° CA) is calculated as shown in Equation 4 every 5 ° CA.

[Formula 4] Nd ← 0.25 × 7 kHz band vibration strength + 1 × 10 kHz band vibration strength
+ 1 × 15 kHz band vibration strength + 1 × 20 kHz band vibration strength Here, Equation 3 and Equation 4 are the same.

In this way, the total value of all narrow frequency bands is calculated by using the weighting coefficient Kcn (f) by the above formulas 1 to 4, and this total value is accumulated at intervals of 5 ° CA.
Next, it is determined whether or not the current crank angle is 90 ° CA of the combustion stroke in the #n cylinder (S114). If it has not yet reached 90 ° CA (NO in S114), the routine proceeds to ignition timing feedback control processing (S120: FIG. 2).

  Thereafter, as long as the state is less than 90 ° CA in the range of 0 ° to 90 ° CA, the above-described processing of steps S106 to S112 is repeated, and here, the processing is repeated every 5 ° CA in the current combustion stroke. Accumulated data of all narrow frequency band summed data at 5 ° CA intervals can be obtained by detecting the vibration intensity.

  When the temperature reaches 90 ° CA, in the #n cylinder in the current combustion stroke, the vibration is as illustrated in FIG. 5A with the crank angle as the horizontal axis and the total narrow frequency band combined vibration strength Nd as the vertical axis. Intensity data is obtained.

  If the combustion stroke is 90 ° CA in the #n cylinder (YES in S114), then knock magnitude N is calculated (S116). Here, as the knock intensity N, the vibration intensity Nd shown in FIG. 5A is calculated as a total value (integrated value) from 0 ° CA to 90 ° CA. It should be noted that the maximum value (peak value) in the accumulated data of 5 ° CA vibration intensity may be set as the knock intensity N. Alternatively, a value obtained by dividing the maximum value of the accumulated data by a value representing the vibration intensity of the internal combustion engine 2 in a state where knocking has not occurred may be set as the knock intensity N. Knock strength N may be expressed by other methods.

  Next, a correlation coefficient K with the knock vibration intensity waveform model by vibration waveform analysis is calculated (S118). The knock vibration intensity waveform model is as shown in FIG. 5B and is created in advance as a vibration waveform model when knocking occurs in the internal combustion engine 2.

  This knock vibration intensity waveform model corresponds to vibrations after the peak value of vibration intensity generated by knocking, and is a dimensionless number converted to a value in the range of 0 to 1. Therefore, the values shown in FIG. 5A are normalized by being converted to dimensionless numbers by dividing the peak and subsequent values by the peak value. As a result, as shown in FIG. 5C, it can be compared with the knock vibration intensity waveform model, and the correlation coefficient K can be calculated.

  For example, the absolute value of the deviation between the normalized vibration intensity waveform and the knock vibration intensity waveform model every 5 ° CA is ΔS (I) (I is a natural number), and the vibration intensity in the knock vibration intensity waveform model is expressed by the crank angle. When the integrated value (the area of the knock vibration intensity waveform model) is S, the correlation coefficient K is calculated by the equation K = (S−ΣΔS (I)) / S. Here, ΣΔS (I) is the sum of ΔS (I) from 0 ° CA to 90 ° CA.

  The correlation coefficient K obtained in this way is calculated as a value closer to “1” as the shape of the vibration intensity waveform is closer to the shape of the knock vibration intensity waveform model. When the vibration intensity waveform includes a vibration waveform due to a factor other than knocking, the correlation coefficient K decreases and approaches “0”.

When knock magnitude N and correlation coefficient K are calculated in this way, the routine proceeds to ignition timing feedback control processing (S120: FIG. 2).
The ignition timing feedback control process (FIG. 2) will be described.

First, it is determined whether THW ≧ 60 ° C. (S130). If THW <60 ° C. (NO in S130), the routine proceeds to ignition timing setting (S142) as described above.
If THW ≧ 60 ° C. (YES in S130), knock determination is executed based on the obtained knock magnitude N and correlation coefficient K (S132).

In this knock determination, it is determined that knocking is present when both of the following two conditions are satisfied, and it is determined that knocking is not present when either or both are not satisfied.
Condition 1: Knock strength N ≧ knock determination threshold value J (i)
Condition 2: correlation coefficient K ≧ correlation determination value K1
The knock determination threshold value J (i) in the condition 1 is a value that is updated by correction for each region of the operating state of the internal combustion engine in each cylinder in accordance with the knock magnitude N and the occurrence frequency thereof under a certain condition. It is a determination value for determining the presence or absence of occurrence. Here, (i) represents a region, which is a region divided by the load of the internal combustion engine 2 and the internal combustion engine speed NE. The load is the amount of air taken into the combustion chamber 6 per revolution of the internal combustion engine 2 and is a value obtained from the intake air amount GA and the internal combustion engine speed NE.

The correlation determination value K1 in the condition 2 is a correlation determination reference value set in advance corresponding to the model of the internal combustion engine 2, and is set to “0.6”, for example.
If either or both of the conditions 1 and 2 are not satisfied ("No knocking" is determined in S132), an advance processing is performed on the feedback correction value for feedback control of the ignition timing (S134). Here, if the feedback correction value is represented by an advance value, the feedback correction value is increased.

  If both of the above conditions 1 and 2 are satisfied ("Knocking is determined" in S132), the feedback correction value for correcting the ignition timing is retarded (S136). If the feedback correction value is represented by an advance value, the feedback correction value is decreased. In some cases, a negative value may be set.

  When the feedback correction value is calculated in step S134 or step S136, it is determined whether or not the ignition timing learning condition is satisfied (S138). If it is established (YES in S138), learning of the ignition timing learned value, that is, the ignition timing learned value is updated (S140).

Then, after step S140 or after determining NO in step S138, an ignition timing setting process (S142) is performed.
In the configuration described above, the relationship with the claims corresponds to an internal combustion engine knock determination device in which the ECU 4 includes a plurality of frequency band vibration intensity detection means, determination target value calculation means, and weight setting means. In the knocking control process (FIG. 1) executed by the ECU 4, the vibration intensity detection in each narrow frequency band in step S112 is a process as a plurality of frequency band vibration intensity detecting means. This corresponds to processing as a determination target value calculation means. The setting of the weighting coefficient Kcn (f) in steps S106 to S110 and step S112 and the use in equations 1 to 4 correspond to the processing as the weight setting means.

According to the first embodiment described above, the following effects can be obtained.
(1) In step S112 of the knocking control process (FIG. 1), the weighting coefficient Kcn (f) set for low rotation or high rotation in step S108 or step S110 is used.

  Thus, since the influence of knocking vibration on the knock sensor 40 is different for each cylinder, the weighting coefficient Kcn (f) is set for each cylinder. Specifically, as shown in the case of NE ≦ 3000 rpm in FIG. 3, the weighting coefficient Kcn (f) is increased for the cylinders (# 1, # 4 cylinders) farther from the knock sensor 40, and the cylinders (# 2, # 2) are the opposite. The weighting coefficient Kcn (f) is made smaller as # 3 cylinder).

  Further, since the influence of knocking vibration differs depending on the frequency band of vibration even in the same cylinder, weighting is set for each frequency band, here for each narrow frequency band. Specifically, the weighting coefficient Kcn (f) is decreased in the narrow frequency band of 7 kHz that is the lowest frequency band, and the weighting coefficient Kcn (f) is increased in the narrow frequency bands of 10 kHz, 15 kHz, and 20 kHz that are higher frequency bands. is doing.

  As a result, when knock determination (S132) is performed based on the vibration intensity calculated in step S112 and the vibration intensity waveform, the accuracy of the knock determination can be improved.

(2) When the internal combustion engine 2 is in the high speed region (NE> 3000 rpm), the weights for each cylinder are the same or close to each other. Here, they are the same as shown in FIG.
In the high rotation region, the influence of the vibration on the knock sensor 40 due to the difference in cylinder is smaller than that in the low rotation region. For this reason, when the internal combustion engine 2 is in the high speed region, the weights for each cylinder are the same or close to each other, so that the position of the cylinder is appropriately reflected along with the difference in frequency band even if the internal combustion engine speed NE is different. Since the vibration intensity and the vibration intensity waveform can be obtained, the knock determination accuracy can be improved.

(3) Since the highly accurate knock determination can be performed as described above, the highly accurate knocking control based on the ignition timing becomes possible.
[Embodiment 2]
In the present embodiment, the hardware configuration is as shown in FIG. 6 differs from the first embodiment in that the process of FIG. 6 is performed as the knocking control process executed by the ECU 4, and the process of FIG. 7 is performed as the ignition timing feedback control process.

  When the knocking control process (FIG. 6) is started, it is first determined whether or not the coolant temperature THW is 60 ° C. or higher (S202). This process is the same as step S102 in FIG. If cooling water temperature THW is less than 60 ° C. (NO in S202), the process proceeds to an ignition timing feedback control process (S216: FIG. 7).

  In the ignition timing feedback control process (FIG. 7), it is first determined whether or not the coolant temperature THW ≧ 60 ° C. (S230). In this case, since the coolant temperature THW <60 ° C. again (NO in S230), the ignition timing is immediately set (S244). This process is the same as step S142 in FIG. Thereafter, as long as the cooling water temperature THW <60 ° C., the above-described processing continues.

  If the coolant temperature THW rises due to continued operation of the internal combustion engine 2 and THW ≧ 60 ° C. (YES in S202), based on the detection results of the engine speed sensor 28 and the cam position sensor 38, It is determined whether any of the cylinders is within a certain crank angle range in the combustion stroke (S204). This process is also the same as step S104 in FIG. If any of the cylinders is outside the combustion stroke of 0 ° to 90 ° CA (NO in S204), the process proceeds to the ignition timing feedback control process (S216: FIG. 7).

  If any of the cylinders (represented by “#n cylinder”) is within 0 ° to 90 ° CA of the combustion stroke (YES in S204), the vibration intensity in the next wide frequency band (5 kHz to 20 kHz) and a plurality of The vibration intensity in the narrow frequency band (here, four) (7 kHz, 10 kHz, 15 kHz, 20 kHz) is detected, and the vibration intensity data is accumulated every 5 ° CA (S206).

  Next, the median value VM and the standard deviation σ in the vibration intensity frequency distribution are calculated for each narrow frequency band (S208). In step S208, as illustrated in FIG. 8 in each narrow frequency band, the median value VM and the standard deviation σ are calculated based on the vibration intensity frequency distribution.

  In FIG. 8, the vertical axis represents the frequency and the horizontal axis represents the logarithmic value of the vibration intensity Nd. Actually, the median value VM and the standard deviation σ of such a frequency distribution are repeatedly calculated approximately as shown in Equations 5 and 6 every time the vibration intensity Nd is detected.

[Formula 5] VM ← VM + (Nd−VM) / x
[Formula 6] σ ← σ + (Nd−σ) / y
Here, in Equations 5 and 6, VM and σ on the right side of “←” are previous values, and VM and σ on the left side are current values. x and y are positive values for weighted average weighting, and a process in which a certain amount of delay occurs with respect to the change in the vibration intensity Nd, so-called “smoothing process” is performed.

Equations 5 and 6 are executed by the ECU 4 for each ignition cycle, and the median value VM and the standard deviation σ are repeatedly calculated for each of the four narrow frequency bands according to the value of the vibration intensity.
Next, it is determined whether or not the current crank angle is 90 ° CA of the combustion stroke in the #n cylinder (S210). If it has not yet reached 90 ° CA (NO in S210), the routine proceeds to ignition timing feedback control processing (S216: FIG. 7).

  If the combustion stroke is 90 ° CA in the #n cylinder (YES in S210), then the knock intensity N in the wide frequency band and each narrow frequency band is calculated (S212). Here, the knock intensity N is the same as that in the first embodiment, and as shown in FIG. 5A, the vibration intensity Nd is a total value from 0 ° CA to 90 ° CA (integrated value). Calculate as

  As described in the first embodiment, the peak value may be set as the knock magnitude N, and the peak value is divided by a value representing the vibration intensity of the internal combustion engine 2 in a state where knocking has not occurred. May be used as the knock strength N, and the knock strength N may be expressed by other methods. In this way, knock strength N is obtained for each of the wide frequency band and the four narrow frequency bands.

  Next, based on the vibration intensity accumulation data in the wide frequency band, a correlation coefficient K with the knock vibration intensity waveform model by vibration waveform analysis is calculated (S214). The knock vibration intensity waveform model is the model as described in the first embodiment, and is shown in FIG. The calculation of the correlation coefficient K is as described in step S118 (FIG. 1) of the first embodiment.

  When the knock intensity N for the wide frequency band and each narrow frequency band and the correlation coefficient K for the wide frequency band are calculated in this way, the process proceeds to the ignition timing feedback control process (S216: FIG. 7). To do.

The ignition timing feedback control process (FIG. 7) will be described.
First, it is determined whether THW ≧ 60 ° C. (S230). If THW <60 ° C. (NO in S230), the routine proceeds to ignition timing setting (S244) as described above.

  If THW ≧ 60 ° C. (YES in S230), knock determination is executed based on the correlation coefficient K of the wide frequency band and the knock intensity N of the wide frequency band and the narrow frequency band (S232, S234).

  First, as knock strength determination, it is determined whether or not the knock strength N in the wide frequency band is equal to or greater than the knock determination threshold J (i) (S232). This knock determination threshold value J (i) is as described in condition 1 in step S132 of FIG.

  If knock intensity N in the wide frequency band <knock determination threshold value J (i) (NO in S232), “no knocking” determination is made, and an advance processing is performed on the feedback correction value for feedback control of the ignition timing. (S236). This process is the same as step S134 in FIG.

  If the knock intensity N of the wide frequency band is greater than or equal to the knock determination threshold value J (i) (YES in S232), the determination regarding the vibration intensity waveform is executed next. That is, it is determined whether or not all of the following three conditions are satisfied (S234).

Condition 1: wide frequency band correlation coefficient K ≧ correlation determination value K1 (for example, K1 = 0.6)
Condition 2: Knock strength N in a narrow frequency band of 7 kHz is ranked first or second in the entire narrow frequency band. Condition 3: Knock strength N ≧ VM + 3 · in any two narrow frequency bands. σ (intensity A in FIG. 8)
If all three conditions are satisfied (YES in S234), it can be determined that knocking has occurred in terms of the waveform. Therefore, “knocking present” is determined, and the feedback correction value for correcting the ignition timing is retarded. Is made (S238). This process is the same as step S136 in FIG.

After step S236 or step S238, steps S240 to 244 are executed. This process is as described in steps S138 to S142 in FIG.
In the configuration described above, the ECU 4 corresponds to the internal combustion engine knock determination device, the determination process in step S234 corresponds to the vibration intensity waveform determination, the condition 1 is the broadband determination, and the conditions 2 and 3 are the narrow band. Corresponds to judgment.

According to the second embodiment described above, the following effects can be obtained.
(1) In the ignition timing feedback control process (FIG. 7), knock determination is performed based on vibration intensity determination (S232) and vibration intensity waveform determination (S234). Among these, the vibration intensity waveform determination (S234) includes not only the condition 1 which is the broadband determination for determining the waveform correlation between the broadband waveform and the knocking waveform but also the conditions 2 and 3 which are the narrowband determination. It has become.

  In the vibration intensity waveform determination, the vibration intensity waveform determination in only the wide frequency band according to the condition 1 is not sufficient as the knocking vibration waveform determination. That is, even if the knocking vibration is not large, a vibration intensity waveform similar to the knocking waveform may appear in a wide frequency band due to noise, and the condition 1 may be satisfied.

However, in the case of knocking vibration, a characteristic vibration intensity state appears in a narrow frequency band which is a partial band within the wide frequency band.
Therefore, in order to distinguish such a waveform that is similar to the knocking waveform due to noise and a waveform in the case of actual knocking vibration, vibration intensity waveform determination in which conditions 2 and 3 are ANDed with condition 1 (S234). It is said.

  As described above, by adding the narrow band determination (conditions 2 and 3) together with the wide band determination (condition 1), it is possible to appropriately distinguish the waveform due to noise and the waveform in the case of actually knocking vibration.

  As a result, the accuracy of the vibration intensity waveform determination (S234) can be improved, so that the accuracy of the knock determination performed by both the vibration intensity determination (S232) and the vibration intensity waveform determination (S234) can also be improved. it can.

  (2) Particularly, in condition 2, the vibration intensity state in the 7 kHz band where the vibration due to knocking is likely to be superimposed in the wide frequency band (7 kHz to 20 kHz band) is determined. Here, the determination is made by comparing the vibration intensity with other narrow frequency bands. For this reason, the comparison can be made easily, and the vibration intensity integrated value in the 7 kHz band can be used as an index to further improve the accuracy of the vibration intensity waveform determination.

  (3) As condition 3, when the vibration intensity (here, the integrated value) in two or more narrow frequency bands is greater than or equal to three times the standard deviation than the median value VM of vibration intensity distribution (≧ VM + 3 · σ) It is determined that the vibration intensity state is high. When knocking occurs, a large vibration is superimposed on two or more narrow frequency bands, so such a condition is included. This can improve the accuracy of vibration intensity waveform determination.

Since Condition 3 and Condition 2 are the logical product condition of Condition 1 which is the waveform determination only in the original wide frequency band, more accurate vibration intensity waveform determination is possible.
(4) As described above, the highly accurate knocking control based on the ignition timing becomes possible as in the first embodiment.

[Embodiment 3]
In the present embodiment, knock condition N is detected and compared for each of the four narrow frequency bands of 7 kHz, 10 kHz, 15 kHz, and 20 kHz in condition 2 of step S234 of the ignition timing feedback control process (FIG. 7). However, the fourth embodiment differs from the second embodiment in that the four knock intensities N are compared after the weighting process is executed. Other points are the same as those of the second embodiment.

  Knock intensity N (7k) is a vibration intensity corresponding to a 7 kHz band, knock intensity N (10 k) is a 10 kHz band, knock intensity N (15 k) is a 15 kHz band, and knock intensity N (20 k) is a vibration intensity corresponding to a 20 kHz band. Each knock intensity Nc as a comparison object is calculated as follows.

[Formula 7] Knock strength Nc (7k) <-Knock strength N (7k) x Kw (7k)
[Formula 8] Knock strength Nc (10k) <-Knock strength N (10k) x Kw (10k)
[Formula 9] Knock strength Nc (15k) <-Knock strength N (15k) x Kw (15k)
[Formula 10] Knock strength Nc (20k) <-Knock strength N (20k) x Kw (20k)
Here, the weighting coefficients Kw (7k), Kw (10k), Kw (15k), and Kw (20k) have a relationship as shown in FIG. That is, the weighting coefficient Kw tends to decrease as the frequency increases. This corresponds to an output (voltage) tendency corresponding to the frequency of the knock sensor 40 at the same vibration intensity. As shown in FIG. 9B, the output of the knock sensor 40 tends to increase as the vibration frequency increases. The weighting coefficient Kw is reduced as the vibration frequency increases.

  As a result, according to the third embodiment, the effects of the second embodiment are produced, and correction is performed with the weighting coefficient Kw that takes into account the output tendency of the knock sensor 40, whereby the knock strength N with higher accuracy is obtained. Comparison determination is possible.

Therefore, highly accurate knock determination and highly accurate knocking control based on the ignition timing associated therewith are possible.
[Embodiment 4]
In the second and third embodiments, the knock magnitude N detected for each of the four narrow frequency bands of 7 kHz, 10 kHz, 15 kHz, and 20 kHz in the condition 3 in step S234 of the ignition timing feedback control process (FIG. 7) is It was determined to be equal to or greater than “the median value VM + 3σ of vibration intensity distribution” in a narrow frequency band.

However, vibrations generated in the same combustion stroke tend to be similar in standard deviation σ in any narrow frequency band.
Therefore, in the present embodiment, with respect to the standard deviation σ, four narrow frequency bands of 7 kHz, 10 kHz, 15 kHz, and 20 kHz are obtained using the standard deviation σ obtained from any one of the four narrow frequency bands. It is determined that the knock magnitude N detected every time is equal to or greater than “the median value VM + 3σ of the vibration intensity distribution in each narrow frequency band”. For example, assuming that the standard deviation σ in the narrow frequency band of 7 kHz or 10 kHz is the representative standard deviation, the knock intensity N detected for each of the four narrow frequency bands is “the median value VM + 3 × representative standard of the vibration intensity distribution in each narrow frequency band”. It is determined that the deviation is equal to or greater than “deviation”.

Other configurations are the same as those in the second or third embodiment.
As a result, according to the fourth embodiment, the effects of the second embodiment or the third embodiment are produced, and the calculation of the standard deviation σ used in the condition 3 can be calculated by one standard deviation σ. Therefore, even if the calculation load of the ECU 4 is reduced, the vibration intensity waveform determination can be performed quickly and easily without reducing the accuracy.

[Other embodiments]
In the first embodiment, the boundary for switching the weighting coefficient Kcn (f) is set to NE = 3000 rpm in step S106 of the knocking control process (FIG. 1). However, it corresponds to the type of the internal combustion engine and the knocking control design. Thus, the switching boundary may be set to less than 3000 rpm or may be set to a value exceeding 3000 rpm.

  In the first embodiment, instead of providing a boundary for switching the weighting coefficient Kcn (f), the weighting coefficient Kcn (f) may be continuously changed according to the internal combustion engine speed NE. . Alternatively, the weighting coefficient Kcn (f) may be changed step by step in a plurality of steps.

  In the first embodiment, the weighting coefficient Kcn (f) is actually switched based on the situation in the 7 kHz band of the # 1 and # 4 cylinders, but the other narrow frequency band is also switched. May be. Also, for the # 2 and # 3 cylinders, the weighting coefficient Kcn (f) in any narrow frequency band may be switched based on the situation.

  In the second to fourth embodiments, the condition 2 is determined by determining the integrated value of the vibration intensity in the combustion stroke of the internal combustion engine as the knock intensity N, or by performing further weighting processing. Instead, in condition 2, the peak value of the vibration intensity in the combustion stroke region of the internal combustion engine may be determined as the knock intensity N, or may be determined by further weighting.

  In Embodiments 2 to 4, two conditions of conditions 2 and 3 are used as logical product conditions for condition 1, but one condition of conditions 2 and 3 is logical for condition 1 It may be a product condition.

  In the second to fourth embodiments, in the condition 3, “the knock intensity N ≧ VM + 3 · σ in the two narrow frequency bands” is set, but instead of “VM + 3 · σ” on the right side of this equation, “VM + n A value such as σ ”(5 ≧ n ≧ 2) may be used. That is, as shown in FIG. 8, it may be set in the range of “VM + 2 · σ” to “VM + 5 · σ”.

  In this condition 3, “knock strength N ≧ VM + 3 · σ in two narrow frequency bands” may be set to “knock strength N ≧ VM + n · σ in three narrow frequency bands”. And knock strength N ≧ VM + n · σ ”.

  In the above embodiments, the number of narrow frequency bands is four, but it may be two or three, or five or more. In accordance with the number of narrow frequency bands, the number of narrow frequency bands having a large rank or knock strength N in the conditions 2 and 3 is set.

  In each of the above embodiments, the port injection spark ignition type internal combustion engine is used. However, the present invention can also be applied to a cylinder injection spark ignition type internal combustion engine.

  DESCRIPTION OF SYMBOLS 2 ... Internal combustion engine, 4 ... ECU, 6 ... Combustion chamber, 8 ... Intake passage, 8a ... Surge tank, 8b ... Branch pipe, 8c ... Intake port, 10 ... Fuel injection valve, 12 ... Spark plug, 14 ... Piston, 16 ... crankshaft, 18 ... exhaust passage, 18a ... exhaust port, 20 ... intake valve, 22 ... exhaust valve, 24 ... accelerator pedal, 26 ... throttle valve, 28 ... engine speed sensor, 30 ... cooling water temperature sensor, 32 ... throttle Opening sensor 34... Intake air amount sensor 36. Accelerator operation amount sensor 38. Cam position sensor 40. Knock sensor

Claims (22)

A knock determination device for determining knock based on vibration intensity and vibration intensity waveform detected by a knock sensor provided in an internal combustion engine having a plurality of cylinders,
A plurality of frequency band vibration intensity detecting means for obtaining a vibration intensity detected by the knock sensor for each of a plurality of frequency bands;
The vibration intensities obtained by the plurality of frequency band vibration intensity detecting means are added up for all the frequency bands to obtain a vibration intensity for making the knock determination and a vibration intensity waveform indicating the transition of the vibration intensity. A determination target value calculating means;
A weight setting means for setting a weight for the vibration intensity for each cylinder and for each frequency band based on a situation when the sum is calculated by the determination target value calculating means;
An internal combustion engine knock determination device comprising: 2. The internal combustion engine knock determination device according to claim 1, wherein the weight setting unit weights the vibration intensity for each cylinder and for each frequency band based on an arrangement relationship between the knock sensor and each cylinder as the situation. Is set, the internal combustion engine knock determination device. 2. The internal combustion engine knock determination device according to claim 1, wherein the weight setting unit sets a weight for the vibration intensity for each cylinder and for each frequency band based on an internal combustion engine operating state as the situation. An internal combustion engine knock determination device. 2. The internal combustion engine knock determination device according to claim 1, wherein the weighting setting unit performs the vibration for each cylinder and for each frequency band based on an arrangement relationship between the knock sensor and each cylinder as the situation and an internal combustion engine operating state. An internal combustion engine knock determination device that sets weighting to strength. 5. The internal combustion engine knock determination device according to claim 2, wherein the weighting setting unit increases the weighting with respect to the vibration intensity of the cylinder as the cylinder is farther from the knock sensor. 6. 5. The internal combustion engine knock determination device according to claim 3, wherein the weighting setting unit increases the difference in weighting corresponding to the difference in operating state of the internal combustion engine toward a lower frequency band side. Knock determination device. 7. The internal combustion engine knock determination device according to claim 6, wherein the weighting setting means eliminates or reduces the weighting difference corresponding to the difference in the operating state of the internal combustion engine in a cylinder closer to the knock sensor. An internal combustion engine knock determination device. In the internal combustion engine knock determination device according to claim 3, 4, 6, or 7, as the internal combustion engine operating state, the weighting for each cylinder by the weighting setting means is the same as the internal combustion engine speed is in a high speed region. Alternatively, an internal combustion engine knock determination device characterized in that it is close. The internal combustion engine knock determination device according to any one of claims 1 to 8, wherein the plurality of frequency bands have a 7 kHz band as a lowest frequency band, and the weighting is set based on the situation in the 7 kHz band. An internal combustion engine knock determination device characterized by increasing the difference between the two. An internal combustion engine knock determination device that performs knock determination based on vibration intensity determination and vibration intensity waveform determination with respect to vibration detected by a knock sensor provided in the internal combustion engine,
The vibration intensity waveform determination is
Broadband determination for determining a waveform correlation between a wideband waveform and a knocking waveform that is a vibration intensity waveform in a wide frequency band in the vibration,
Narrow band determination for determining a vibration intensity state in a narrow frequency band that is a partial band in the wide frequency band;
An internal combustion engine knock determination device comprising: 11. The internal combustion engine knock determination device according to claim 10, wherein the narrow frequency band is a narrow frequency band in which vibration due to knocking has a strong tendency to overlap within the wide frequency band. . 12. The internal combustion engine knock determination device according to claim 11, wherein the wide frequency band is a 7 kHz band as a minimum frequency band, and the minimum frequency band is a narrow frequency band in which vibration due to knocking is highly likely to be superimposed. Internal combustion engine knock determination device. The internal combustion engine knock determination device according to any one of claims 10 to 12, wherein the vibration intensity waveform determination shows a high correlation in the wide band determination and a high vibration intensity state in the narrow band determination. An internal combustion engine knock determination device characterized in that what is shown is a condition for knock determination. The internal combustion engine knock determination device according to any one of claims 10 to 13, wherein the vibration intensity state determined by the narrow band determination is an integrated value of vibration intensity in an internal combustion engine combustion stroke region. An internal combustion engine knock determination device. The internal combustion engine knock determination device according to any one of claims 10 to 13, wherein the vibration intensity state determined by the narrow band determination is a peak value of vibration intensity in an internal combustion engine combustion stroke region. An internal combustion engine knock determination device. 16. The internal combustion engine knock determination device according to claim 14, wherein the narrow band determination is performed by setting a plurality of narrow frequency bands in the wide frequency band, and vibration in the narrow frequency band in which vibration due to knocking is easily superimposed. An internal combustion engine knock determination device that determines that a high vibration intensity state is indicated when the intensity is larger than vibration intensity in another narrow frequency band. The internal combustion engine knock determination device according to claim 14 or 15, wherein the narrow band determination sets a plurality of narrow frequency bands within the wide frequency band, and vibration intensity in any two or more narrow frequency bands is set. An internal combustion engine knock determination device that determines that a high vibration intensity state is indicated when the standard deviation is larger than the median of the vibration intensity distribution by n (5 ≧ n ≧ 2) times or more. 16. The internal combustion engine knock determination device according to claim 14, wherein the narrow band determination is performed by setting a plurality of narrow frequency bands in the wide frequency band, and vibration in the narrow frequency band in which vibration due to knocking is easily superimposed. When the intensity is larger than the vibration intensity in other narrow frequency bands, and the vibration intensity in any two or more narrow frequency bands is less than the median of the vibration intensity distribution. An internal combustion engine knock determination device that determines that a high vibration intensity state is exhibited when n (5 ≧ n ≧ 2) times or more. The internal combustion engine knock determination device according to any one of claims 16 to 18, wherein the vibration intensity in each narrow frequency band is weighted corresponding to a detection characteristic associated with a difference in vibration frequency of the knock sensor. An internal combustion engine knock determination device. 20. The internal combustion engine knock determination device according to claim 19, wherein the weighting is increased toward a lower frequency side. The internal combustion engine knock determination device according to claim 17 or 18, wherein the standard deviation is calculated based on a vibration intensity distribution in any one of a plurality of narrow frequency bands. An internal combustion engine knock determination device characterized by being used in a band. A knock control device that performs knock determination based on vibration intensity determination and vibration intensity waveform determination with respect to vibration detected by a knock sensor provided in an internal combustion engine, and adjusts an ignition timing based on a result of the knock determination,
The internal combustion engine knock control device according to any one of claims 1 to 21, wherein the knock determination is performed by the internal combustion engine knock determination device according to any one of claims 1 to 21.

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