JP2004353531A - Knock control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a knock control device of an internal combustion engine which is capable of correctly determining presence/absence of knock occurrence, and adequately controlling the running state of the internal combustion engine. <P>SOLUTION: The vibration waveform signal from a knock sensor 10 which is generated in an internal combustion engine is separated into a plurality of frequency components by BPFs 22a-22e of a knock detection circuit 20. The knock waveform shape as the total of each vibration mode can be expressed by the knock waveform shape set by the frequency component consisting of a value that the plurality of frequency components are intensity-integrated for each predetermined section of a predetermined crank angle and a value that the intensity-integrated values are added for the same section. Presence/absence of knock occurrence in the internal combustion engine can be correctly determined and the running state of the internal combustion engine can be adequately controlled by using the knock waveform shape with the corrected knock intensity according to the degree of deviation of the knock waveform shape from the ideal knock waveform stored in an ideal knock waveform storage unit 26. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a knock control device for an internal combustion engine that controls an operation state of the internal combustion engine based on knock determination.
[0002]
[Prior art]
Conventionally, as prior art documents related to a knock control device for an internal combustion engine, those disclosed in Japanese Patent Publication No. 6-60621 and Japanese Patent Application Laid-Open No. 2001-227400 are known.
[0003]
In the former, knocking is detected by detecting only the most remarkably oscillating component of frequency components generated when knocking of the internal combustion engine occurs, statistically processing the peak value or the integrated value of a predetermined section, and comparing the result with a predetermined level. A technique for determining whether or not occurrence has occurred is shown.
[0004]
In the latter, a technique is described in which knock is determined based on a relationship between a generation period of a knock frequency component and a peak value in a vibration waveform signal generated in an internal combustion engine.
[Patent Document 1] Japanese Patent Publication No. 6-60621 (pages 1 to 4)
[Patent Document 2] JP-A-2001-227400 (page 2)
[0005]
[Problems to be solved by the invention]
By the way, the frequency components which remarkably vibrate due to knocking of the internal combustion engine are not always the same, and the frequency components at which the vibration intensity increases each time knocking occurs are different. Therefore, when only one frequency component is extracted as in Japanese Patent Publication No. 6-60621, other vibration modes (such as a secondary vibration waveform with respect to the primary vibration waveform) are large, and when the extracted frequency component is small, Knock cannot be detected. Furthermore, when it is determined whether or not knock has occurred from only the peak value or the integrated value in a predetermined section, when electrical and mechanical noise occurs in a frequency band near the knock frequency component, the increase in frequency intensity due to the noise is generated. However, there is a problem that it is erroneously determined that knocking has occurred despite no occurrence of knocking because it cannot be distinguished from an increase in frequency intensity due to the above.
[0006]
Also, as in Japanese Patent Application Laid-Open No. 2001-227400, when the presence or absence of knock is determined based only on the relationship between the occurrence period of the knock frequency component and the peak value, it is possible to distinguish the knock from the knock when a plurality of noises are superimposed. There was a problem that it disappeared.
[0007]
Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to provide a knock control device for an internal combustion engine that can accurately determine whether knock has occurred and appropriately control the operating state of the internal combustion engine.
[0008]
[Means for Solving the Problems]
According to the knock control apparatus for an internal combustion engine of claim 1, the vibration waveform signal generated in the internal combustion engine detected by the signal detection means is separated into a plurality of frequency components by the frequency separation means, and the separated frequency components are separated. A knock waveform shape is set by a waveform shape setting means based on a value obtained by integrating the strength of the engine for each predetermined section consisting of a predetermined crank angle, and the presence or absence of knock occurrence in the internal combustion engine is determined by the knock determination means based on the knock waveform shape. The operating state of the internal combustion engine is controlled by the knock control means according to the result. In this manner, the vibration waveform signal generated in the internal combustion engine is separated into a plurality of frequency components, and a knock waveform shape set by a value obtained by integrating the plurality of separated frequency components into strengths for each predetermined section having a predetermined crank angle. According to this, the knock waveform shape as the sum of the respective vibration modes can be represented, and according to the knock waveform shape, the presence or absence of knock in the internal combustion engine is accurately determined, so that the operation state of the internal combustion engine is appropriately determined. Is controlled.
[0009]
The waveform shape setting means in the knock control device for an internal combustion engine according to claim 2, wherein the value obtained by integrating the intensity of a plurality of frequency components separated by the frequency separating means for each predetermined section having a predetermined crank angle is the same as the value of the same section. The knock waveform shape is set by at least two or more frequency components consisting of the value added every time. In this manner, the vibration waveform signal generated in the internal combustion engine is separated into a plurality of frequency components, and the value obtained by integrating the values of the separated plurality of frequency components for each predetermined section having a predetermined crank angle is equal to the value of the same section. According to the knock waveform shape set by at least two or more frequency components including the value added for each case, the knock waveform shape as a sum of the respective vibration modes can be represented. By accurately determining whether knock has occurred in the engine, the operating state of the internal combustion engine is appropriately controlled.
[0010]
According to the knock control apparatus for an internal combustion engine of the third aspect, the ideal knock waveform of the vibration waveform signal generated in the internal combustion engine is preset by the ideal waveform setting means, and the ideal knock waveform is set by the waveform shape setting means. The correction is performed in a direction in which the knock intensity decreases in accordance with the degree of deviation from the knock waveform. This prevents a noise waveform having a large intensity but a waveform shape different from that of knock from being erroneously determined as knock.
[0011]
According to the waveform shape setting means in the knock control device for an internal combustion engine of claim 4, when the intensity increase portion up to the peak of the knock waveform shape is slower than the intensity increase rate of the ideal knock waveform, the intensity is small because it is suspicious of the knock waveform. Is corrected in the following direction. In other words, since the intensity increase rate of the intensity increase portion up to the peak of the knock waveform shape varies widely, when the intensity increase rate is steep as compared with the intensity increase rate of the ideal knock waveform, the intensity is kept as it is and is gentle. Sometimes the intensity is corrected in the direction of decreasing intensity. This prevents the knock detection accuracy from deteriorating due to variations in the rate of increase in intensity up to the peak of the knock waveform shape.
[0012]
In the knock control device for a knock control device for an internal combustion engine according to claim 5, the knock intensity is corrected so that the knock intensity increases as the knock waveform shape approaches the ideal knock waveform by comparison with the ideal knock waveform. According to the knock intensity corrected in this manner, a knock-specific waveform shape is exhibited only when the knock frequency component is present, so that the separability between the noise waveform shape and the knock waveform shape, which are difficult to distinguish, is improved.
[0013]
The knock determination means in the knock control device for an internal combustion engine according to claim 6, wherein the background level created based on the intensity of the frequency component of the signal range not including the knock frequency component is used as a reference for the knock determination. It is possible to make a knock determination for each combustion cycle regardless of the operation state of
[0014]
In the knock determination means in the knock control device for an internal combustion engine according to claim 7, the background level created based on the average value or the sum of the intensities of the frequency components in the signal range not including the knock frequency component is used as a reference for knock determination. Thus, the knock determination can be performed by comparing the strength of the knock frequency component with the frequency component other than the knock, regardless of the operating state of the internal combustion engine.
[0015]
In the knock determination means in the knock control device for an internal combustion engine according to claim 8, the knock intensity at each frequency component of the knock waveform shape corrected by comparison with the ideal knock waveform is used as a knock determination value, so that the knock determination value for each knock occurrence Deterioration of knock detection accuracy due to different vibration modes is prevented.
[0016]
In the knock control device for an internal combustion engine according to the ninth aspect, the attenuation shape of the ideal knock waveform is set based on the attenuation shape of the in-cylinder pressure during the expansion stroke of the internal combustion engine. That is, the damping shape of the pressure vibration of the knock has a great effect of the pressure decrease in the expansion stroke of the internal combustion engine. Therefore, the ideal knock waveform can be easily set based on the damping shape of the in-cylinder pressure at this time.
[0017]
In the ideal waveform setting means in the knock control device for an internal combustion engine according to claim 10, the attenuation shape of the in-cylinder pressure may be the actual in-cylinder pressure detected in the internal combustion engine, the in-cylinder pressure estimated from the operating state of the internal combustion engine, or a predetermined value. It is set based on the set in-cylinder pressure for each of one or more operation regions. That is, the attenuation shape of the in-cylinder pressure, which is used as a reference when setting the ideal knock shape, is determined based on an actual detected value, an estimated value based on the operating state of the internal combustion engine, or a predetermined value for each of one or more operating regions. It is easily set based on the value.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples.
[0019]
FIG. 1 is a block diagram showing an overall configuration of a knock control device for an internal combustion engine according to one example of an embodiment of the present invention.
[0020]
In FIG. 1, reference numeral 1 denotes a knock sensor, and a knock sensor 10 includes a vibration sensor that is installed on an engine block wall of an internal combustion engine (not shown) and detects vibration or an in-cylinder pressure sensor that is installed in a cylinder and detects an in-cylinder pressure. is there. The sensor signal from the knock sensor 10 is input to the input circuit 11 and is taken into the knock detection circuit 20 at the subsequent stage. Therefore, the input circuit 11 adjusts the sensor signal so as to be within a predetermined voltage range. Further, the sensor signal is passed through the filter 12 before being taken into the knock detection circuit 20. As this filter 12, an LPF (Low Pass Filter: low-pass filter) for cutting high-frequency components or a BPF (Band Pass Filter: band-pass filter) for extracting only a specific frequency component is set to prevent aliasing.
[0021]
Next, the sensor signal that has passed through the filter 12 is taken into the knock detection circuit 20 via an A / D (analog-digital) converter 21. The sampling cycle of the knock detection circuit 20 with respect to the sensor signal via the A / D converter 21 is fast enough to sufficiently extract a knock frequency component specific to knock. In this embodiment, the frequency components subjected to A / D conversion by the A / D converter 21 are input to five BPFs 22a, 22b, 22c, 22d, and 22e having different pass bands, and the three BPFs 22a, 22b, and 22c use the three frequency components. The knock frequency component and the BPFs 22d and 22e separate the signal into frequency components in a signal range that does not include two knock frequency components (hereinafter simply referred to as “noise frequency components”).
[0022]
The frequency components separated by the BPFs 22a to 22e are input to the interval integrating units 23a to 23e, respectively, and the intensity of each frequency component is integrated for each predetermined interval. This integration section is defined by a crank angle [° CA (Crank Angle)] period. That is, by defining the crank angle rather than the real time, it is possible to extract a characteristic waveform at the time of knock occurrence regardless of the engine speed. In addition, the sum of the respective knock frequency components integrated by the section calculators 23a, 23b, and 23c is obtained by the adder 24, so that a knock waveform is extracted even if a knock occurs in which a plurality of vibration modes appear simultaneously. You can do it.
[0023]
In the comparison calculation units 25a to 25d, each knock frequency component by the section calculation units 23a to 23c and the addition unit 24 is compared with an ideal knock waveform having an ideal knock waveform shape stored in advance in the ideal knock waveform storage unit 26. The knock intensity is corrected so that the knock intensity increases as the waveform approaches the ideal knock waveform. As this correction method, for example, a coefficient (error coefficient) E corresponding to the degree of deviation from the ideal knock waveform is calculated, and the knock intensity is multiplied by (1−E) as a correction coefficient. Here, the ideal knock waveform may be determined by theoretical calculation such as a combustion model formula, or the knock shape may be set in advance for each operating condition of each internal combustion engine by adaptation. In addition, when using an in-cylinder pressure sensor, there is a high correlation between the damping shape of the resonance vibration peculiar to knock and the attenuating shape of the average pressure in the cylinder due to combustion and piston movement. The attenuation shape of the ideal knock waveform may be defined.
[0024]
Next, in the knock intensity selection unit 27, a frequency component used for knock determination is selected from the knock intensity corrected by comparison with the ideal knock waveform for each frequency component by the comparison calculation units 25a to 25d. Here, as the selected frequency component, the vibration mode that appears remarkably for each knock varies, so that the one having the maximum corrected knock strength or the sum of the respective frequency components is used.
[0025]
On the other hand, in the BGL (Back Ground Level: background level) creating unit 28, a BGL is created based on the noise frequency components from the section integrating units 23d and 23e in order to make a knock determination regardless of the operating state of the internal combustion engine. As the BGL creation method, similarly to the knock frequency component, a corrected noise intensity obtained by comparing / correcting the noise frequency component with the ideal knock waveform is calculated, or the sum or average value of the noise frequency components is calculated. .
[0026]
The comparison / knock determination unit 29 performs a comparison calculation using the knock intensity selected by the knock intensity selection unit 27 and the BGL created by the BGL creation unit 28. If the knock intensity is equal to or greater than a predetermined value, the knock is determined. As the comparison method, the determination may be made from the ratio between the knock strength and the BGL, or the determination may be made from the difference between the knock strength and the BGL.
[0027]
Further, a reference position signal and a cylinder discrimination signal of a crankshaft (not shown) of the internal combustion engine are input from an electronic control unit (ECU) 30 for controlling the internal combustion engine to the A / D converter 21 of the knock detection circuit 20. A knock determination signal corresponding to a knock determination result from a comparison calculation / knock determination unit 29 of a knock detection circuit 20, which will be described later, is input to the internal combustion engine control ECU 30. In addition, various sensor signals from the internal combustion engine, such as a crank angle sensor, an intake air amount sensor, and a water temperature sensor, are input to the internal combustion engine control ECU 30. The ignition timing, the fuel injection amount, and the like are calculated by the internal combustion engine control ECU 30 based on these input signals, and a correction according to the knock determination result is executed, so that the igniter 40 and the injector (fuel injection valve) 50 are appropriately controlled. Will be done.
[0028]
Here, the internal combustion engine control ECU 30 includes a CPU serving as a central processing unit for executing various known arithmetic processing, a ROM storing a control program and a control map, a RAM storing various data, and a B / U (backup). It is configured as a logical operation circuit including a RAM, an input / output circuit, and a bus line connecting them.
[0029]
Next, a schematic operation of knock detection / judgment by the knock detection circuit 20 with respect to the vibration waveform signal from the knock sensor 10 will be described with reference to time charts of FIGS.
[0030]
A waveform sample section signal is generated based on the falling edge of the reference position signal from the internal combustion engine control ECU 30 (time t0 shown in FIG. 2), and the waveform sample section signal is "ON" for each predetermined section. In the section (time t0 to time t1 shown in FIG. 2), the frequency components Fa (S1,1, S1,2, S1,3,..., S1, n) via the BPFs 22a to 22e by the section calculation units 23a to 23e. Fe (S5,1, S5,2, S5,3, ..., S5, n) are respectively integrated. Then, a period from the end of the integration section in which the current waveform sample section signal is “OFF” to the start of the integration section in which the next waveform sample section signal is “ON” (time t1 to time t2 shown in FIG. 2). Next, knocks 1, 2, and 3 are obtained as detection waveforms based on knock frequency components Fa, Fb, and Fc, and the intensities of knocks 1, 2, and 3 and the ideal knock waveform stored in ideal knock waveform storage unit 26 are obtained. The calculated values are compared with each other by the comparison calculation sections 25a to 25d to calculate the corrected knock strength.
[0031]
Among these corrected knock intensities, the maximum corrected knock intensity is selected by the knock intensity selector 27. Then, the comparison operation / knock determination unit 29 uses the maximum corrected knock intensity from the knock intensity selection unit 27 and the BGL from the BGL creation unit 28 based on the noise frequency components Fd and Fe as described below. A knock determination parameter is calculated. The knock determination parameter is compared with a preset determination threshold to determine whether knock has occurred. Then, at the next fall of the reference position signal, that is, at the start of the next integration section when the waveform sample section signal becomes “ON” (time t2 shown in FIG. 2), the current integration value is reset. At this time, a knock determination signal corresponding to the knock determination result is output to ECU 30 for controlling the internal combustion engine, and the same operation is repeated thereafter.
[0032]
Next, a description will be given based on a flowchart of FIG. 3 showing a processing procedure of knock determination in knock detection circuit 20 used in a knock control device for an internal combustion engine according to one example of an embodiment of the present invention. This knock determination routine is repeatedly executed by knock detection circuit 20 for each combustion cycle of the internal combustion engine based on the reference position signal and cylinder determination signal from internal combustion engine control ECU 30.
[0033]
In FIG. 3, first, in step S101, the process waits until the integration section starts, and then proceeds to step S102, where the vibration waveform signal is separated into a plurality of frequency components, and digital filtering is performed on each frequency component. In step S103, the intensity integration is performed on the frequency components subjected to the digital filter processing. The process proceeds to step S104 to determine whether the predetermined crank angle has elapsed. If the determination condition in step S104 is not satisfied, that is, if the predetermined crank angle has not elapsed, the process returns to step S102, and the same processing is repeatedly executed.
[0034]
On the other hand, when the determination condition of step S104 is satisfied, that is, when the predetermined crank angle has elapsed, the process proceeds to step S105, and the integrated intensity value of step S103 is stored in the RAM (not shown) of knock detection circuit 20. The process proceeds to step S106, where the integrated intensity value in step S103 is reset. The process moves to step S107, and it is determined whether or not the accumulation section has ended. If the determination condition of step S107 is not satisfied, that is, if the integration section is not completed, the process returns to step S102, and the same processing is repeatedly executed.
[0035]
On the other hand, when the determination condition of step S107 is satisfied, that is, when the integration section is completed, the process proceeds to step S108, and the corrected knock intensity is calculated by comparing the knock frequency component with an ideal knock waveform described later. Proceeding to step S109, the maximum corrected knock strength is selected from the corrected knock strengths calculated in step S108. In step S110, a BGL (background level) creation process for a noise frequency component, which will be described later, is executed.
[0036]
In step S111, the maximum correction knock intensity selected in step S109 is divided by the BGL (background level) created in step S110 to calculate a knock determination parameter. In step S112, it is determined whether the knock determination parameter calculated in step S111 exceeds a predetermined determination threshold. When the determination condition of step S112 is satisfied, that is, when the knock determination parameter exceeds the determination threshold and is large, the process proceeds to step S113, knock is determined, and this routine ends. On the other hand, if the determination condition of step S112 is not satisfied, that is, if the knock determination parameter is smaller than or equal to the determination threshold, the process proceeds to step S114, it is determined that there is no knock, and this routine ends.
[0037]
Next, a description will be given based on a flowchart of FIG. 4 showing a processing procedure of comparison calculation with an ideal knock waveform in step S108 in the knock determination of FIG.
[0038]
In FIG. 4, in step S201, a peak value p of each knock frequency component is searched. In step S202, an ideal knock waveform a (θ) calculation process described later is executed. In step S203, the scale adjustment is performed by multiplying the ideal knock waveform a (θ) calculated in step S202 by the peak value p searched in step S201. The process proceeds to step S204, where a correlation calculation process of the waveform before the peak value described later is executed. The process proceeds to step S205, where a correlation calculation process for the post-peak value waveform described below is performed. In step S206, the correction intensity before the peak value and the correction intensity after the peak value are added to calculate the correction knock intensity, and this routine ends.
[0039]
Next, a description will be given based on a flowchart of FIG. 5 showing a processing procedure of the ideal knock waveform calculation of step S202 in the comparison calculation with the ideal knock waveform of FIG.
[0040]
In FIG. 5, in step S301, the in-cylinder pressure is detected. The process moves to step S302, where low-pass filtering is performed. In step S303, a logarithmic decrement per predetermined crank angle is calculated. The process proceeds to step S304, where an attenuation factor calculation process is executed, and the routine ends. In this way, as shown in FIG. 6, an ideal knock waveform a (θ) based on the attenuation shape of the in-cylinder pressure is created.
[0041]
Next, a description will be given based on a flowchart of FIG. 7 showing a processing procedure of the correlation calculation of the waveform before the peak value in step S204 in the comparison calculation with the ideal knock waveform of FIG.
[0042]
In FIG. 7, in step S401, it is determined whether the ideal knock waveform a (θ) is smaller than the detection waveform s (θ). When the determination condition of step S401 is satisfied, that is, when the ideal knock waveform a (θ) is smaller than the detection waveform s (θ), the process proceeds to step S402, and the peak-value-corrected knock magnitude is calculated by the following equation (1). This routine ends.
[0043]
(Equation 1)
Corrected knock intensity before peak value ← a (θ) × [1- {s (θ) −a (θ)} / a (θ)] (1)
[0044]
On the other hand, if the determination condition in step S401 is not satisfied, that is, if the ideal knock waveform a (θ) is greater than or equal to the detected waveform s (θ), the process proceeds to step S403, where the corrected knock intensity before the peak value is equal to the ideal knock waveform a (θ). θ), and this routine ends.
[0045]
Next, a description will be given based on a flowchart of FIG. 8 showing a processing procedure of the correlation calculation of the waveform after the peak value in step S205 in the comparison calculation with the ideal knock waveform of FIG.
[0046]
8, in step S501, the difference d (θ) between the ideal knock waveform a (θ) and the detected waveform s (θ) is calculated by the following equation (2).
[0047]
(Equation 2)
d (θ) ← | s (θ) −a (θ) | (2)
[0048]
Next, the routine proceeds to step S502, where the corrected knock intensity after the peak value is calculated by the following equation (3), and this routine ends.
[0049]
[Equation 3]
Corrected knock intensity after peak value ← a (θ) × {1−d (θ) / a (θ)} (3)
[0050]
Next, a description will be given based on a flowchart of FIG. 9 showing a processing procedure of creating a BGL (background level) in step S110 in the knock determination of FIG.
[0051]
In FIG. 9, in step S601, the average intensity of the noise frequency component is calculated, and this routine ends.
[0052]
As described above, the knock control device for an internal combustion engine according to the present embodiment includes a signal detection unit including the knock sensor 10 for detecting a vibration waveform signal generated in the internal combustion engine (not shown), the input circuit 11, and the filter 12; Frequency separating means including an A / D converter 21 and BPFs 22a to 22e of a knock detecting circuit 20 for separating a vibration waveform signal detected by the detecting means into a plurality of frequency components; and a plurality of frequencies separated by the frequency separating means. The section integrating units 23a to 23c of the knock detection circuit 20 that sets the knock waveform shape based on the value obtained by integrating the components Fa to Fc for each of the predetermined sections each including a predetermined crank angle, the adding unit 24, the comparison calculating units 25a to 25d, Knock generation in the internal combustion engine based on the waveform shape setting means achieved by the selection unit 27 and the knock waveform shape by the waveform shape setting means Knock determination means achieved by comparison operation / knock determination section 29 of knock detection circuit 20 for determining presence / absence of knock, and internal combustion engine control ECU 30 for controlling the operating state of the internal combustion engine according to the determination result by the knock determination means And knock control means achieved by the above.
[0053]
Here, in the case of a knock waveform in which one vibration mode is dominant, a knock determination can be made by extracting the vibration component waveform. However, when one knock waveform includes a plurality of vibration modes, the raw waveform of the sensor has an ideal knock waveform because the dominant vibration mode changes during the knock period. Looking only at the waveform shape of each knock frequency component, the knock waveform may deviate greatly from the ideal knock waveform, and the knock may not be determined.
[0054]
On the other hand, a vibration waveform signal generated in the internal combustion engine is separated into a plurality of frequency components, and a knock waveform set by a value obtained by integrating the plurality of separated frequency components for each predetermined section having a predetermined crank angle. According to the shape, a knock waveform shape as a sum of each vibration mode can be represented, and by using the knock waveform shape, the presence or absence of knock in the internal combustion engine can be accurately determined, and the operating state of the internal combustion engine can be appropriately determined. Can be controlled.
[0055]
In addition, the waveform shape setting means achieved by the section integration units 23a to 23c, the addition unit 24, the comparison calculation units 25a to 25d, and the knock intensity selection unit 27 of the knock detection circuit 20 of the knock control device for an internal combustion engine of the present embodiment. Is a value obtained by integrating the intensity of a plurality of frequency components Fa to Fc separated by the frequency separation means including the A / D converter 21 and the BPFs 22a to 22e of the knock detection circuit 20 for each predetermined section having a predetermined crank angle. The knock waveform shape is set by a frequency component consisting of a value obtained by adding a value for each same section.
[0056]
As described above, the vibration waveform signal generated in the internal combustion engine is separated into a plurality of frequency components, and a value obtained by intensity-integrating the separated plurality of frequency components for each predetermined section having a predetermined crank angle is obtained. According to the knock waveform shape set by at least two or more frequency components consisting of a value added to the above, a knock waveform shape as a sum of the respective vibration modes can be represented. It is possible to accurately determine whether knock has occurred in the engine, and to appropriately control the operating state of the internal combustion engine.
[0057]
The knock control device for an internal combustion engine according to the present embodiment uses the ideal knock waveform storage unit 26 of the knock detection circuit 20 that presets an ideal knock waveform shape of a vibration waveform signal generated in the internal combustion engine as an ideal knock waveform. An ideal waveform setting means is provided, wherein the waveform shape setting means corrects the knock intensity in the knock waveform shape according to the degree of deviation from the ideal knock waveform. In other words, by correcting the knock waveform shape in such a manner that the knock intensity becomes smaller as it deviates from the ideal knock waveform, it is possible to prevent a noise waveform having a large intensity but having a waveform shape different from the knock from being erroneously determined as a knock. be able to.
[0058]
Further, the waveform shape setting means achieved by the section integration units 23a to 23c, the addition unit 24, the comparison calculation units 25a to 25d, and the knock intensity selection unit 27 of the knock detection circuit 20 of the knock control device for an internal combustion engine of the present embodiment. Is to correct the knock intensity to be small when the intensity increase portion up to the peak of the knock waveform shape is gentler than the intensity increase rate of the ideal knock waveform. In other words, since the intensity increase rate of the intensity increase portion up to the peak of the knock waveform shape varies widely, when the intensity increase rate is steep as compared with the intensity increase rate of the ideal knock waveform, the intensity is kept as it is and is gentle. Sometimes the intensity is corrected in the direction of decreasing intensity. Thereby, it is possible to prevent the knock detection accuracy from deteriorating due to the variation in the rate of increase in intensity up to the peak of the knock waveform shape.
[0059]
Furthermore, the waveform shape setting achieved by the section integration units 23a to 23c, the addition unit 24, the comparison calculation units 25a to 25d, and the knock intensity selection unit 27 of the knock detection circuit 20 of the knock control device for an internal combustion engine of the present embodiment. The means corrects the knock intensity so that the knock intensity increases as the knock waveform shape approaches the ideal knock waveform. According to the knock intensity corrected in this manner, a knock-specific waveform shape is exhibited only when the knock frequency component is present, so that the separability between the noise waveform shape and the knock waveform shape, which are difficult to distinguish, can be improved.
[0060]
In addition, the knock determination means achieved by the comparison operation / knock determination unit 29 of the knock detection circuit 20 of the knock control device for an internal combustion engine of the present embodiment includes a noise frequency component (a frequency in a signal range not including the knock frequency component). BGL (background level) created based on the intensity of the component) is used as a reference for knock determination. Thus, knock determination can be made for each combustion cycle regardless of the operating state of the internal combustion engine.
[0061]
The knock determination means achieved by the comparison operation / knock determination unit 29 of the knock detection circuit 20 of the knock control device for an internal combustion engine according to the present embodiment includes a noise frequency component (a frequency component of a signal region not including a knock frequency component). BGL) created based on the average value or the sum of the intensities described in (1) is used as a criterion for knock determination. Thus, knock determination can be performed by comparing the strength of the knock frequency component with the frequency component other than knock, regardless of the operating state of the internal combustion engine.
[0062]
The knock determination means achieved by the comparison calculation / knock determination section 29 of the knock detection circuit 20 of the knock control device for an internal combustion engine of the present embodiment includes a knock waveform shape corrected by comparison with an ideal knock waveform. The knock determination value is set based on the knock intensity of the frequency component. Thus, it is possible to prevent the knock detection accuracy from deteriorating due to different vibration modes for each knock occurrence.
[0063]
Further, the ideal waveform setting means achieved by the ideal knock waveform storage section 26 of the knock detection circuit 20 of the knock control device for the internal combustion engine of the present embodiment determines the attenuation shape of the ideal knock waveform by using the in-cylinder pressure during the expansion stroke of the internal combustion engine. Is set with reference to the attenuation shape of. In other words, the damping shape of the pressure vibration of the knock is greatly affected by the pressure decrease in the expansion stroke of the internal combustion engine. Therefore, the ideal knock waveform can be easily set by using the damping shape of the in-cylinder pressure at this time as a reference. it can.
[0064]
Further, the ideal waveform setting means achieved by the ideal knock waveform storage section 26 of the knock detection circuit 20 of the knock control device for the internal combustion engine of the present embodiment is provided by an actual cylinder in which the in-cylinder pressure attenuation shape is detected by the internal combustion engine. It is set based on the internal pressure. That is, the attenuation shape of the in-cylinder pressure, which is used as a reference when setting the ideal knock shape, can be easily set based on the actual detected value.
[0065]
By the way, as shown in the above embodiment, it is ideal to set the ideal knock waveform by using a sensor device such as an in-cylinder pressure sensor capable of directly detecting the in-cylinder pressure. According to the predetermined value for each operating region, the sensor device can be omitted.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of a knock control device for an internal combustion engine according to an example of an embodiment of the present invention.
FIG. 2 is a time chart showing a schematic operation of knock detection / determination by a knock detection circuit of FIG. 1;
FIG. 3 is a flowchart showing a procedure of a knock determination in a knock detection circuit used in a knock control device for an internal combustion engine according to one embodiment of the present invention.
FIG. 4 is a flowchart illustrating a processing procedure of a comparison operation with an ideal knock waveform in the knock determination of FIG. 3;
FIG. 5 is a flowchart illustrating a processing procedure of an ideal knock waveform calculation in a comparison operation with the ideal knock waveform of FIG. 4;
FIG. 6 is an explanatory view showing creation of an ideal knock waveform based on the attenuation shape of the in-cylinder pressure in FIG.
FIG. 7 is a flowchart showing a processing procedure of a correlation calculation of a waveform before a peak value in a comparison calculation with an ideal knock waveform of FIG. 4;
8 is a flowchart illustrating a processing procedure of a correlation calculation of a waveform after a peak value in a comparison calculation with the ideal knock waveform of FIG. 4;
FIG. 9 is a flowchart illustrating a processing procedure of BGL creation in knock determination in FIG. 3;
[Explanation of symbols]
10 Knock sensor
20 Knock detection circuit

Claims (10)

Signal detection means for detecting a vibration waveform signal generated in the internal combustion engine,
Frequency separation means for separating the vibration waveform signal detected by the signal detection means into a plurality of frequency components,
Waveform shape setting means for setting a knock waveform shape by a value obtained by integrating the intensity of a plurality of frequency components separated by the frequency separation means for each predetermined section consisting of a predetermined crank angle,
Knock determination means for determining whether or not knock has occurred in the internal combustion engine based on a knock waveform shape by the waveform shape setting means,
A knock control device for controlling the operating state of the internal combustion engine according to a result of the determination by the knock determination device. The waveform shape setting means includes a value obtained by integrating the intensity of a plurality of frequency components separated by the frequency separation means for each predetermined section having a predetermined crank angle, and a value obtained by adding this value for each same section. The knock control device for an internal combustion engine according to claim 1, wherein the knock waveform shape is set by one or more frequency components. An ideal knock setting unit that presets an ideal knock waveform shape of a vibration waveform signal generated in the internal combustion engine as an ideal knock waveform,
The knock control of an internal combustion engine according to claim 1 or 2, wherein the waveform shape setting means corrects the knock intensity with respect to the knock waveform shape according to a degree of deviation from the ideal knock waveform. apparatus. The waveform shape setting means corrects the knock intensity so that the knock intensity decreases when the intensity increase portion up to the peak of the knock waveform shape is gentler than the intensity increase rate of the ideal knock waveform. Item 4. A knock control device for an internal combustion engine according to Item 3. 4. The knock control apparatus for an internal combustion engine according to claim 3, wherein the waveform shape setting means corrects the knock intensity so that the knock intensity increases as the knock waveform shape approaches the ideal knock waveform. 4. The knock control of an internal combustion engine according to claim 3, wherein the knock determination means uses a background level created based on the intensity of a frequency component in a signal range not including a knock frequency component as a reference for knock determination. apparatus. 4. The knock determination unit according to claim 3, wherein the knock determination unit uses a background level created based on an average value or a sum of the intensities of the frequency components in the signal range that does not include the knock frequency component as a reference for knock determination. 5. Knock control device for internal combustion engine. 4. The internal combustion engine according to claim 3, wherein the knock determination unit sets a knock determination value based on a knock intensity in each frequency component of the knock waveform shape corrected by comparison with the ideal knock waveform. Knock control device. 4. The knock control device for an internal combustion engine according to claim 3, wherein the ideal waveform setting means sets the attenuation shape of the ideal knock waveform based on the attenuation shape of the in-cylinder pressure during an expansion stroke of the internal combustion engine. The ideal waveform setting means is configured to determine the attenuation shape of the in-cylinder pressure by an actual in-cylinder pressure detected in the internal combustion engine, or an in-cylinder pressure estimated from an operation state of the internal combustion engine, or one or more preset cylinder pressures. The knock control device for an internal combustion engine according to claim 9, wherein the setting is performed based on the in-cylinder pressure for each operation region.

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