JP7081420B2 - Knock determination device and knock control device - Google Patents

Description

The present invention relates to a knock determination device for determining the occurrence of knock in an internal combustion engine, and a knock control device for performing knock control for suppressing the occurrence of knock based on the knock determination.

In Patent Document 1, the knock determination is performed as follows. First, the vibration generated in the internal combustion engine is detected. Next, the detection signal is separated into a plurality of knock frequency components and a plurality of other noise frequency components by a plurality of bandpass filters. Next, a knock waveform is obtained by integrating only the knock frequency components among them.

Next, the knock waveform is compared with the ideal knock waveform. Then, the knock intensity is corrected according to the degree of deviation of the knock waveform from the ideal knock waveform. Knock determination is performed based on the corrected knock strength. Knock control is performed based on the knock determination.

Japanese Unexamined Patent Publication No. 2004-353531

In Reference 1, it is necessary to separate the detection signal into a plurality of knock frequency components and noise frequency components by a plurality of bandpass filters. Furthermore, it is also necessary to integrate a plurality of knock frequency components separated by this. Furthermore, it is also necessary to compare the knock waveform obtained thereby with the ideal knock waveform and correct the knock intensity based on the comparison. Therefore, in Cited Document 1, the processing load is large in performing the knock determination.

The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the processing load in performing a knock determination.

The knock determination device of the present invention has a detection unit for detecting vibration generated in an internal combustion engine, and performs a knock determination for determining the occurrence of knock based on the detection result by the detection unit. The knock determination device has a specific unit, a calculation unit, and a determination unit. The specific portion is a waveform obtained based on the detection result, and is a vibration waveform representing a time change of the intensity with the strength of the vibration as the intensity or the intensity with the absolute value of the intensity of the vibration as the intensity. From the absolute value waveform representing the time change of, the second point, which is the maximum point where the intensity is maximum within a predetermined period, and the second point, which is the maximum point within the predetermined period, among the plurality of maximum points where the intensity is maximum. At least three of the first point, which is one of the maximum points existing before the point, and the third point, which is one of the maximum points existing after the second point within the predetermined period. Identify the maximum point. The calculation unit calculates a predetermined feature amount using at least the three maximum points. The determination unit makes the knock determination based on the feature amount.

The present invention has been made by finding the following points. The shape of the vibration waveform has a predetermined difference depending on whether the vibration is due to knocking or non-knocking. Therefore, the knock determination can be performed based on the shape of the vibration waveform. The shape of the vibration waveform can be estimated based on the above features. Therefore, the knock determination can be performed based on the above-mentioned feature amount.

According to the present invention, since the knock determination is performed based on the above-mentioned feature amount calculated by using the above-mentioned three points, the processing as described in Patent Document 1 becomes unnecessary. Specifically, first, it is not necessary to separate the detection signal into a plurality of knock frequency components and a plurality of noise frequency components by a plurality of bandpass filters. Further, the process of integrating a plurality of knock frequency components separated by the process becomes unnecessary. Further, the process of comparing the knock waveform obtained by the process with the ideal knock waveform and correcting the knock intensity based on the comparison becomes unnecessary. Therefore, according to the present invention, the processing load can be reduced in performing the knock determination.

Schematic diagram showing the internal combustion engine of the first embodiment Flow chart showing control by knock control device Graph showing the vibration waveform obtained based on the detection signal A graph showing a vibration waveform different from that in FIG. Graph showing the shape pattern of vibration waveform Flow chart showing shape determination of vibration waveform A graph showing the distribution of shape patterns determined from the first time and the second time Flow chart showing shape determination in the second embodiment A graph showing the distribution of shape patterns determined from the rate of increase and the rate of attenuation In the third embodiment, a graph showing the relationship between the inclination ratio and the knock component. Flow chart showing shape judgment Graph showing absolute value waveforms in other embodiments A graph showing an absolute value waveform different from that in FIG.

Next, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiment, and can be appropriately modified and implemented without departing from the spirit of the invention.

[First Embodiment]
FIG. 1 is a schematic view showing an internal combustion engine 10 of the present embodiment. The internal combustion engine 10 includes an engine block 11, a piston 12, an intake valve 13, an exhaust valve 14, and the like. An accelerator pedal sensor 21, a knock sensor 29, an ECU 30, an electronic throttle 41, an injector 42, an ignition coil 43, and the like are installed in the internal combustion engine 10.

The ECU 30 inputs a request (acceleration request) from the driver via the accelerator pedal sensor 21. Based on the input, the amount of air, the amount of fuel, the ignition timing, etc. are controlled. Specifically, the ECU 30 controls the amount of air by controlling the electronic throttle 41, controls the amount of fuel by controlling the injector 42, and controls the ignition timing by controlling the ignition coil 43.

The knock sensor 29 detects the vibration generated in the internal combustion engine 10. The ECU 30 receives the detection signal from the knock sensor 29 during the gate open period, which is the period during which the gate is open. In the present embodiment, the knock sensor 29 corresponds to the "detection unit" in the present invention. Further, each gate opening period corresponds to the "predetermined period" in the present invention.

FIG. 2 is a flowchart showing a knock determination by the ECU 30 and a knock control based on the knock determination. The ECU 30 includes a digital conversion unit 31 that performs AD conversion (S100), a filter unit 32 that performs BPF processing (S200), a specific unit 33 that performs three-point identification (S300), and a calculation that performs feature amount calculation (S400). It has a unit 34, a shape determination unit 35 that performs shape determination (S500), a knock determination unit 36 that performs knock determination (S600), and a control unit 37 that performs knock control (S700).

The knock sensor 29, the digital conversion unit 31, the filter unit 32, the specific unit 33, the calculation unit 34, the shape determination unit 35, and the knock determination unit 36 constitute a knock determination device (29, 31 to 36). .. The knock determination device (29, 31 to 36) and the control unit 37 constitute a knock control device (29, 31 to 37). The shape determination unit 35 and the knock determination unit 36 are collectively referred to as "determination units 35, 36".

Specifically, the ECU 30 first converts the detection signal received from the knock sensor 29 from the analog signal to the digital signal (A / D conversion) by the digital conversion unit 31 (S100). Next, the filter unit 32 filters the detected signal with only one type of bandpass filter (S200).

Next, from the vibration waveform after the filter processing (S200), the specific unit 33 identifies three points, the first point p1, the second point p2, and the third point p3, which will be described later (S300). Next, the calculation unit 34 calculates the feature amount of the vibration waveform based on the three points (S400). Next, based on the feature amount, the shape determination unit 35 performs shape determination to determine the shape pattern to which the vibration waveform belongs (S500). Next, based on the shape determination, the knock determination unit 36 performs a knock determination for determining the occurrence of knock (S600). Next, based on the knock determination, the control unit 37 performs knock control for suppressing knock (S700).

3 and 4 are graphs showing an example of a vibration waveform after BPF processing (S200). In this vibration waveform, the horizontal axis indicates time, and the vertical axis indicates vibration intensity (detected voltage value). That is, this vibration waveform shows the time change of the vibration intensity. The vibration intensity here is positive in one direction (when the detected voltage value is positive) and negative in the opposite direction (when the detected voltage value is negative). There is.

In the following, a plurality of points at which the intensity of the vibration waveform becomes maximum will be referred to as "maximum points p". Further, the maximum point p that first exceeds the predetermined value Vc within each gate open period is defined as the “first point p1”. Further, the maximum point p at which the strength becomes maximum within each gate open period is defined as "second point p2". Further, the point that finally exceeds the predetermined value Vc within each gate open period is referred to as "third point p3".

Further, the time from the first point p1 to the second point p2 is defined as "first time t1". Further, the time from the second point p2 to the third point p3 is defined as the "second time t2". Further, the time from one to the other of two adjacent maximum points p among the plurality of maximum points p whose intensities exceed a predetermined value Vc within each gate open period is defined as "peak interval t3".

In the present embodiment, the calculation unit 34 calculates the first time t1, the second time t2, and the peak interval t3 as feature quantities (S400).

FIG. 5 is a graph showing each shape pattern of the vibration waveform. Specifically, FIG. 5A shows a damping type shape pattern in which the intensity rapidly increases and then gradually attenuates. If the vibration waveform belongs to the damping type shape pattern, it is likely that the vibration is due to knocking. This is because the knock waveform has a sharp increase in vibration and then gradually attenuates as the piston descends.

FIG. 5B shows a rhombic shape pattern in which the intensity gradually increases and then gradually attenuates. If the vibration waveform belongs to a diamond-shaped pattern, it is unlikely that it is a knock-induced vibration. While the shape of the latter half becomes a vibration waveform similar to the knock waveform (damping type), the vibration due to the piston slap (noise) gradually intensifies and then gradually converges, so the vibration waveform is this piston slap. This is because there is a possibility of vibration (noise) due to.

FIG. 5C shows an increasing shape pattern in which the intensity gradually increases and then rapidly attenuates. If the vibration waveform belongs to the increasing shape pattern, it is unlikely that it is a vibration due to knocking. This is because the vibration waveform has few shape portions similar to the knock waveform (damping type). That is, it is the opposite of the knock waveform, which is abruptly generated and then gradually attenuated as the piston descends.

FIG. 5D shows a rectangular shape pattern in which the intensity rapidly increases and then rapidly attenuates. If the vibration waveform belongs to a rectangular shape pattern, it is unlikely that it is a vibration due to knocking. This is because the rectangular shape pattern is rapidly attenuated, so that there are few shape portions similar to the knock waveform (attenuation type) as a whole. Further, since the vibration (noise) generated in a pulse manner starts instantaneously and then stops instantly, the vibration waveform is likely to be this pulse vibration (noise).

FIG. 5 (e) shows a bi-damping shape pattern in which two damping shapes are arranged side by side. If the vibration waveform belongs to the bi-damping shape pattern, it is unlikely that it is a vibration due to knocking. This is because the bi-attenuation type shape pattern repeats the increase and decrease of the strength twice, so that there are few shape portions similar to the knock waveform (attenuation type) as a whole. Further, since the knock waveform gradually attenuates as the piston descends, it does not occur twice in a row in such a short period of time.

FIG. 6 is a flowchart showing the details of the shape determination (S500) by the shape determination unit 35. First, it is determined whether or not the first time t1 is smaller than the predetermined first threshold value T1 (S511). When it is larger than the first threshold value T1 (S511: NO), it is determined whether or not the second time t2 is larger than the predetermined second threshold value T2 (S514). When it is smaller than the second threshold value T2 (S514: NO), it is determined that the vibration waveform belongs to the increasing shape pattern, and the shape determination (S500) is terminated. On the other hand, when the second time t2 is larger than the second threshold value T2 (S514: YES), it is determined that the vibration waveform belongs to the rhombic shape pattern, and the shape determination (S500) is terminated.

On the other hand, when it is determined in S511 that the first time t1 is smaller than the first threshold value T1 (S511: YES), it is determined whether or not the second time t2 is larger than the second threshold value T2 (S512). When it is smaller than the second threshold value T2 (S512: NO), it is determined that the vibration waveform belongs to the rectangular shape pattern, and the shape determination (S500) is terminated.

On the other hand, when the second time t2 is larger than the second threshold value T2 (S512: YES), it is determined whether or not any peak interval t3 is smaller than the predetermined interval threshold value T3 (S513). When any of the peak intervals t3 is larger than the interval threshold value T3 (S513: NO), it is determined that the vibration waveform belongs to the bi-attenuation type shape pattern, and the shape determination (S500) is terminated. On the other hand, when any of the peak intervals t3 is smaller than the interval threshold value T3 (S513: YES), it is determined that the vibration waveform belongs to the damping type shape pattern, and the shape determination (S500) is terminated.

This will be described again with reference to FIG. The knock determination unit 36 makes a knock determination (S600) based on the result of the shape determination (S500) by the shape determination unit 35. Specifically, in the shape determination (S500), the more the vibration waveform is determined to be a shape pattern closer to the knock waveform, the larger the correction term is set, and the more the shape pattern is determined to be different from the knock waveform. , Set the correction term smaller.

More specifically, when the shape determination unit 35 determines that the vibration waveform belongs to the damping type shape pattern, the knock determination unit 36 determines that knock has occurred and sets the correction term to "1". Set to. Further, when the shape determination unit 35 determines that the vibration waveform belongs to the diamond-shaped shape pattern, the knock determination unit 36 determines that the possibility of knocking is moderate, and sets the correction term to ". Set to "0.5". Further, when the shape determination unit 35 determines that the vibration waveform belongs to the increasing type, rectangular or bi-damping type shape pattern, the knock determination unit 36 determines that the possibility of knocking is low. , Set the correction term to "0.1". Further, when the specific unit 33 does not detect the first point p1 to the third point p3, that is, the three maximum points p whose intensities exceed a predetermined value Vc, the knock determination unit 36 determines that knock has not occurred. Judgment is made and the correction term is set to "0".

Based on the knock determination (S600), the control unit 37 performs knock control (S700). Specifically, the ignition angle, which is the crank angle for igniting the internal combustion engine 10, is retarded by a predetermined ignition retard angle from a predetermined ignition reference angle. The ignition retard angle amount is a value obtained by multiplying a predetermined basic ignition retard angle amount by a correction term.

Therefore, for example, when the correction term changes from "0" to "1", the ignition retard angle is retarded due to the increase in the ignition retard angle amount. Hereinafter, the control for retarding the ignition angle in this way is referred to as "ignition retard control". On the other hand, for example, when the correction term changes from "1" to "0", the ignition retard angle amount decreases, so that the ignition angle advances and returns to the ignition reference angle. Hereinafter, the control for advancing the ignition angle in this way is referred to as "advance angle return control", and the ignition retard angle amount reduced by the advance angle return control is referred to as "advance angle return amount". Excessive ignition retard control can be suppressed by performing advance return control.

FIG. 7 is a graph showing the distribution of the shape pattern to which the vibration waveform is determined to belong from the first time t1 and the second time t2. When the first time t1 is larger than the first threshold value T1 (above) and the second time t2 is larger than the second time t2 (right) (upper right), the vibration waveform is determined to belong to the rhombic shape pattern. .. Further, when the first time t1 is larger than the first threshold value T1 (above) and the second time t2 is smaller than the second threshold value T2 (left) (upper left), the vibration waveform belongs to the increasing shape pattern. It is judged.

Further, when the first time t1 is smaller than the first threshold value T1 (lower) and the second time t2 is larger than the second threshold value T2 (right) (lower right), the vibration waveform is attenuated or bi-damped. It is determined that it belongs to the shape pattern. Further, when the first time t1 is smaller than the first threshold value T1 (lower) and the second time t2 is smaller than the second threshold value T2 (left) (lower left), it is determined that the vibration waveform belongs to the rectangular shape pattern. Will be done.

According to this embodiment, the following effects can be obtained. Feature quantities (t1 to t3) are calculated using the above three points (p1 to p3), the shape pattern to which the vibration waveform belongs is determined based on the feature quantities, and knock determination and knock control are performed based on the shape pattern. Therefore, the processing as described in Patent Document 1 becomes unnecessary. Therefore, the processing load can be reduced when performing knock determination and knock control.

Further, in the BPF processing (S200), since the detection signal is filtered by the bandpass filter, a part of the noise can be removed from the vibration waveform. Therefore, the accuracy of the knock determination (S600) and the knock control (S700) performed based on the vibration waveform can be improved as compared with the case where the removal is not performed. Further, since noise is removed by only one type of bandpass filter, it is not necessary to perform a plurality of filter processes by a plurality of bandpass filters. Therefore, since the detection signal is not separated into a plurality of frequency components, the process of integrating the plurality of frequency components becomes unnecessary. Therefore, the processing load can be reduced.

Further, in the three-point identification (S300), the maximum point p whose intensity first exceeds the predetermined value Vc within each gate open period is set as the first point p1, so that the first point calculated by the feature amount calculation (S400) is used. Time t1 becomes as long as possible. Further, in the three-point identification (S300), the maximum point p whose intensity exceeds the predetermined value Vc at the end within each gate open period is set to the third point p3, so that the second point is calculated by the feature amount calculation (S400). The time t2 is also as long as possible. Therefore, the shape of the vibration waveform can be captured in as wide a range as possible. This makes it easier to capture the overall shape of the vibration waveform. Therefore, the knock determination (S600) and the knock control (S700), which are to be performed based on the vibration waveform, can be easily performed with high accuracy.

Further, in the feature amount calculation (S400), the shape on the front side of the second point p2 in the vibration waveform can be captured based on the first time t1. Further, based on the second time t2, the shape behind the second point p2 in the vibration waveform can be captured. Therefore, by using the second time t2 in addition to the first time t1, it is possible to capture the shape before and after the second point p2 in the vibration waveform. Therefore, it becomes easier to capture the entire shape of the vibration waveform as compared with the case of capturing the shape of only one of the front side or the rear side of the second point p2 in the vibration waveform. Therefore, the knock determination (S600) and the knock control (S700), which are to be performed based on the vibration waveform, can be easily performed with high accuracy.

Further, in the shape determination (S500), since the shape pattern to which the vibration waveform belongs is determined, it becomes easy to efficiently grasp the characteristics of the shape of the vibration waveform.

Further, in the shape determination (S500), as shown in the lower part of FIG. 7, when the first time t1 is smaller than the first threshold value T1, the vibration waveform may be a damping type (high possibility of knocking). There is sex. Therefore, in the knock determination (S600), it becomes easy to largely determine the possibility that knock has occurred, and in the knock control (S700), it becomes easy to increase the ignition retard angle amount. As described above, it becomes easy to determine the possibility of knock generation by a simple process, and thereby it becomes easy to perform a knock determination (S600) and a knock control (S700) by a simple process.

Further, in the shape determination (S500), as shown on the right side of FIG. 7, when the second time t2 is larger than the second threshold value T2, the vibration waveform may be a damping type (high possibility of knocking). There is. Therefore, in the knock determination (S600), it becomes easy to largely determine the possibility that knock has occurred, and in the knock control (S700), it becomes easy to increase the ignition retard angle amount. As described above, it becomes easy to determine the possibility of knock generation by a simple process, and thereby it becomes easy to perform a knock determination (S600) and a knock control (S700) by a simple process.

Further, in the shape determination (S500), when any of the peak intervals t3 shown in FIG. 5 (e) and the like is larger than the predetermined interval threshold value T3, the vibration waveform is a bi-damped type (high possibility of noise). Most likely to belong to a pattern. Therefore, in the knock determination (S600), it is easy to determine that the possibility of knocking is low, and in the knock control (S700), it is easy to reduce the ignition retard angle amount. As described above, it becomes easy to determine the possibility of knock generation by a simple process, and thereby it becomes easy to perform a knock determination (S600) and a knock control (S700) by a simple process.

Further, in the knock control (S700), since the ignition retard angle amount is determined based on the feature amount (t1 to t3), the ignition retard angle amount can be adjusted according to the possibility of knock occurrence. Further, since the advance angle return amount is also determined based on the feature amount (t1 to t3), the advance angle return amount can be adjusted according to the possibility of knock occurrence.

[Second Embodiment]
Next, the second embodiment will be described. In the description of the present embodiment, the same or corresponding members as those of the first embodiment are designated by the same reference numerals, and only the points different from those of the first embodiment will be described.

First, the parameters used in the present embodiment will be described with reference to FIGS. 3 and 4. Hereinafter, the value obtained by subtracting the intensity at the first point p1 from the intensity at the second point p2 is defined as the increase amount v1. Further, the value (v1 / t1) obtained by dividing the increase amount v1 by the first hour t1 is defined as the increase rate g1. Further, the value obtained by subtracting the intensity at the third point p3 from the intensity at the second point p2 is defined as the attenuation amount v2. Further, the value (v2 / t2) obtained by dividing the attenuation amount v2 by the second time t2 is defined as the attenuation factor g2. In the present embodiment, the calculation unit 34 calculates the increase rate g1 and the attenuation rate g2 in addition to the peak interval t3 as the feature amount.

FIG. 8 is a flowchart showing a shape determination (S500) by the shape determination unit 35 of the present embodiment. First, it is determined whether or not the increase rate g1 is larger than the predetermined increase threshold value G1 (S521). When it is smaller than the increase threshold value G1 (S521: NO), it is determined whether or not the attenuation factor g2 is smaller than the predetermined attenuation threshold value G2 (S524). When it is larger than the attenuation threshold value G2 (S524: NO), it is determined that the vibration waveform belongs to the increasing shape pattern, and the shape determination (S500) is terminated. On the other hand, when the damping factor g2 is smaller than the damping threshold value G2 (S524: YES), it is determined that the vibration waveform belongs to the rhombic shape pattern, and the shape determination (S500) is terminated.

Further, when it is determined in S521 that the increase rate g1 is larger than the increase threshold value G1 (S511: YES), it is determined whether or not the attenuation rate g2 is smaller than the attenuation threshold value G2 (S522). When the damping factor g2 is larger than the damping threshold value G2 (S522: NO), it is determined that the vibration waveform belongs to the rectangular shape pattern, and the knock determination (S500) is terminated.

On the other hand, when the attenuation factor g2 is smaller than the attenuation threshold value G2 (S522: YES), it is determined whether or not any peak interval t3 is smaller than the predetermined interval threshold value T3 (S523). When any of the peak intervals t3 is larger than the interval threshold value T3 (S523: NO), it is determined that the vibration waveform belongs to the bi-attenuation type shape pattern, and the knock determination (S500) is terminated. On the other hand, when any of the peak intervals t3 is smaller than the interval threshold value T3 (S523: YES), it is determined that the vibration waveform belongs to the damping type shape pattern, and the knock determination (S500) is terminated.

FIG. 9 is a graph summarizing the distribution of shape patterns determined from the increase rate g1 and the attenuation rate g2. When the increase rate g1 is larger than the increase threshold value G1 (above) and the damping rate g2 is larger than the attenuation threshold value G2 (right) (upper right), the vibration waveform is determined to belong to the rectangular shape pattern. Further, when the increase rate g1 is larger than the increase threshold value G1 (above) and the damping rate g2 is smaller than the attenuation threshold value G2 (left) (upper left), the vibration waveform belongs to the damping type or the bi-damping type shape pattern. It is judged.

Further, when the increase rate g1 is smaller than the increase threshold value G1 (lower) and the damping rate g2 is larger than the damping threshold value G2 (right) (lower right), the vibration waveform is determined to belong to the increasing shape pattern. .. Further, when the increase rate g1 is smaller than the increase threshold value G1 (lower) and the damping rate g2 is smaller than the damping threshold value G2 (left) (lower left), the vibration waveform is determined to belong to the rhombic shape pattern.

According to the present embodiment, since the increase rate g1 is used in the shape determination (S500), the shape of the front portion of the vibration waveform is captured by using the increase amount v1 in addition to the first time t1. Therefore, it becomes easier to accurately grasp the shape of the front portion of the vibration waveform. Further, since the damping factor g2 is used, the shape of the rear portion of the vibration waveform is captured by using the damping amount v2 in addition to the second time t2. Therefore, it becomes easier to accurately grasp the shape of the rear portion of the vibration waveform.

Further, in the shape determination (S500), as shown in the upper part of FIG. 9, when the increase rate g1 is larger than the increase threshold value G1, the vibration waveform may belong to the damping type (high possibility of knocking) shape pattern. There is. Therefore, in the knock determination (S600), it is easy to determine the possibility that knock has occurred, and in the knock control (S700), it is easy to increase the ignition retard angle amount. As described above, it becomes easy to determine the possibility of knock generation by a simple process, and thereby it becomes easy to perform a knock determination (S600) and a knock control (S700) by a simple process.

Further, in the shape determination (S500), as shown on the left side of FIG. 9, when the damping factor g2 is smaller than the damping threshold value G2, the vibration waveform may belong to the damping type (high possibility of knocking) shape pattern. There is. Therefore, in the knock determination (S600), it is easy to determine the possibility that knock has occurred, and in the knock control (S700), it is easy to increase the ignition retard angle amount. As described above, it becomes easy to determine the possibility of knock generation by a simple process, and thereby it becomes easy to perform a knock determination (S600) and a knock control (S700) by a simple process.

[Third Embodiment]
Next, the third embodiment will be described. In the description of the present embodiment, the same or corresponding members as those of the first embodiment are designated by the same reference numerals, and only the points different from those of the first embodiment will be described.

FIG. 10 is a graph for explaining the concept of shape determination (S500) and knock determination (S600) in the present embodiment. In the present embodiment, the calculation unit 34 calculates the slope ratio r, which is a value obtained by dividing the increase rate g1 by the attenuation rate g2, in addition to the peak interval t3, as the feature amount (S400). The determination units 35 and 36 determine that the larger the slope ratio r, the more waveform components (knock components) closer to the knock waveform, and the smaller the slope ratio r, the more waveform components (noise components) far from the knock waveform. do. The details are as shown below.

FIG. 11 is a flowchart showing a shape determination (S500) by the shape determination unit 35 of the present embodiment. First, it is determined whether or not any of the peak intervals t3 is larger than the interval threshold value T3 (S531). When any of the peak intervals t3 is larger than the interval threshold value T3 (S531: YES), it is determined that the vibration waveform belongs to the bi-attenuation type shape pattern, and the shape determination (S500) is terminated.

On the other hand, when any peak interval t3 is smaller than the interval threshold value T3 (S531: NO), the first point p1 and the second point p2 are the same maximum point p, that is, the second point having the maximum intensity. It is determined whether or not the point p2 is the head of the array of the maximum points p whose intensity exceeds the predetermined value Vc (S532). When the second point p2 is the head of the array (S532: YES), it is determined that the vibration waveform belongs to the damping type shape pattern, and the shape determination (S500) is terminated.

On the other hand, when the second point p2 is not the head of the sequence, the second point p2 and the third point p3 are the same maximum point p, that is, the second point p2 having the maximum intensity has a predetermined intensity. It is determined whether or not it is the end of the sequence of the maximum point p exceeding the value Vc (S533). When the second point p2 is the end of the array (S533: YES), it is determined that the vibration waveform belongs to the increasing shape pattern, and the shape determination (S500) is terminated.

On the other hand, when the second point p2 is not the end of the sequence (S533: NO), the condition that the inclination ratio r is larger than the predetermined lower inclination ratio threshold R1 and smaller than the predetermined upper inclination ratio threshold R2. It is determined whether or not the condition is satisfied (S534). When the inclination ratio r satisfies the condition (S534: YES), it is determined that the vibration waveform belongs to the rhombic shape pattern, and the shape determination (S500) is terminated.

On the other hand, when the inclination ratio r does not satisfy the condition (S534: NO), it is determined whether or not the inclination ratio r is larger than the upper inclination ratio threshold value R2 (S535). When the inclination ratio r is larger than the upper inclination ratio threshold value R2 (S535: YES), it is determined that the vibration waveform belongs to the damping type shape pattern, and the shape determination (S500) is terminated. On the other hand, when the inclination ratio r is smaller than the upper inclination ratio threshold value R2 (S535: NO), the result in S534 shows that it is smaller than the lower inclination ratio threshold value R1, so that the vibration waveform has an increasing shape pattern. It is determined that the shape belongs to, and the shape determination (S500) is terminated.

According to the present embodiment, in the shape determination (S500), when the inclination ratio r shown in FIG. 10 is larger than the inclination ratio threshold value R2, the vibration waveform may belong to the damping type (high possibility of knocking) shape pattern. Highly sex. Therefore, in the knock determination (S600), it is easy to determine the possibility that knock has occurred, and in the knock control (S700), it is easy to increase the ignition retard angle amount. As described above, it becomes easy to determine the possibility of knock generation by a simple process, and thereby it becomes easy to perform a knock determination (S600) and a knock control (S700) by a simple process.

[Other embodiments]
This embodiment can also be modified and implemented as follows. For example, instead of specifying the first point p1 to the third point p3 from the vibration waveforms shown in FIGS. 3 and 4, as shown in FIGS. 12 and 13, the absolute value of the vibration intensity (detection). It is also possible to specify the first point p1 to the third point p3 from the absolute value waveform showing the time change of the intensity with the absolute value of the voltage value as the intensity. That is, in this case, in the absolute value waveform, the maximum point where the intensity first exceeds the predetermined value Vc is the first point p1, the maximum point where the intensity is maximum is the second point p2, and the intensity is finally the predetermined value. The maximum point beyond Vc is the third point p3. According to this embodiment, the shape of the vibration waveform is captured not only on the positive side of the intensity in the vibration waveform but also on the negative side, so that the shape of the vibration waveform can be captured more accurately. Further, at this time, instead of determining the shape pattern to which the vibration waveform belongs, it is also possible to determine the shape pattern to which the absolute value waveform belongs.

Further, for example, the BPF process (S200) by the filter unit 32 can be omitted. Further, for example, in the three-point specification (S300), three points are specified from a part of the period within the gate open period, that is, the part of the period is set as the "predetermined period" in the present invention. It can also be carried out.

Further, for example, the first point p1 may be changed to any one of the other maximum points p existing before the second point p2. Further, for example, the third point p3 may be changed to any one of the maximum points p existing after the second point p2.

Further, for example, the knock determination unit 36 can be implemented as follows. When the shape determination unit 35 determines that the vibration waveform belongs to the damping type shape pattern, the knock determination unit 36 determines that knocking has occurred and sets the correction term to "1". On the other hand, when the shape determination unit 35 determines that the vibration waveform belongs to a shape pattern other than the damping type, the knock determination unit 36 determines that knock has not occurred and sets the correction term to "0". do.

Further, for example, the shape determination unit 35 can be eliminated and the knock determination unit 36 can directly perform the knock determination based on the feature amount. Specifically, for example, in the second embodiment, it can be carried out as follows. When the increase rate g1 is larger than the predetermined upper threshold value, the knock determination unit 36 determines that knock has occurred and sets the correction term to “1”. Further, when the increase rate g1 is smaller than the above upper threshold value and larger than the predetermined lower threshold value, it is determined that the possibility of knocking is moderate, and the correction term is set to "0". .5 ". Further, when the increase rate g1 is smaller than the above lower threshold value, it is determined that the possibility of knocking is low, and the correction term is set to "0.1".

Further, for example, in the knock control (S700), instead of performing the ignition retard angle control, the effective compression ratio is lowered by changing the timing of driving the intake valve 13, thereby controlling the knock suppression. , Can also be implemented.

10 ... Internal combustion engine, 29 ... Knock sensor, 33 ... Specific unit, 34 ... Calculation unit, 35 ... Shape determination unit, 36 ... Knock determination unit, p ... Maximum point, p1 ... 1st point, p2 ... 2nd point, p3 ... 3rd point, t1 ... 1st time, t2 ... 2nd time, t3 ... peak interval, v1 ... increase amount, v2 ... attenuation amount, r ... slope ratio.

Claims (13)

Knock determination devices (29, 31 to In 36),
A waveform obtained based on the detection signal, the vibration waveform representing the time change of the intensity with the strength of the vibration as the intensity, or the time change of the intensity with the absolute value of the intensity of the vibration as the intensity. From the absolute value waveform, of the plurality of maximum points (p) at which the intensity becomes maximum, the second point (p2), which is the maximum point at which the intensity becomes maximum within a predetermined period, and the second point (p2) within the predetermined period. The first point (p1), which is one of the maximum points existing before the two points, and the third point (p1), which is one of the maximum points existing after the second point within the predetermined period. A specific portion (33) that identifies at least three of the maximum points in p3), and
A calculation unit (34) that calculates a predetermined feature amount (t1 to t3, g1, g2, r) using at least the three maximum points, and
Judgment units (35, 36) that perform the knock determination based on the feature amount, and
Have,
The calculation unit increases the amount (v1), which is the value obtained by subtracting the intensity at the first point from the intensity at the second point, in the time from the first point to the second point. The rate of increase (g1), which is the value divided by a certain first time (t1), is calculated as the feature amount.
When the increase rate is larger than the predetermined increase threshold value (G1), the determination unit determines more likely that the knock has occurred in the knock determination than when the increase rate is smaller than the increase threshold value. A knock judgment device that makes it easier to do. The calculation unit calculates the attenuation amount (v2), which is the value obtained by subtracting the intensity at the third point from the intensity at the second point, in the time from the second point to the third point. The attenuation rate (g2), which is the value divided by a certain second time (t2), is calculated as the feature amount.
When the attenuation rate is smaller than the predetermined attenuation threshold value (G2), the determination unit determines more likely that the knock has occurred in the knock determination than when it is larger than the attenuation threshold value. The knock determination device according to claim 1 , which facilitates the operation. Knock determination devices (29, 31 to In 36),
A waveform obtained based on the detection signal, the vibration waveform representing the time change of the intensity with the strength of the vibration as the intensity, or the time change of the intensity with the absolute value of the intensity of the vibration as the intensity. From the absolute value waveform, of the plurality of maximum points (p) at which the intensity becomes maximum, the second point (p2), which is the maximum point at which the intensity becomes maximum within a predetermined period, and the second point (p2) within the predetermined period. The first point (p1), which is one of the maximum points existing before the two points, and the third point (p1), which is one of the maximum points existing after the second point within the predetermined period. A specific portion (33) that identifies at least three of the maximum points in p3), and
A calculation unit (34) that calculates a predetermined feature amount (t1 to t3, g1, g2, r) using at least the three maximum points, and
Judgment units (35, 36) that perform the knock determination based on the feature amount, and
Have ,
The calculation unit calculates the attenuation amount (v2), which is the value obtained by subtracting the intensity at the third point from the intensity at the second point, in the time from the second point to the third point. The attenuation rate (g2), which is the value divided by a certain second time (t2), is calculated as the feature amount.
When the attenuation rate is smaller than the predetermined attenuation threshold value (G2), the determination unit determines more likely that the knock has occurred in the knock determination than when it is larger than the attenuation threshold value. A knock determination device that makes it easier to do. The first time (1st time), which is the time from the first point to the second point, for the increase amount (v1), which is the value obtained by subtracting the strength at the first point from the intensity at the second point. The value divided by t1) is defined as the rate of increase (g1).
The second time (2), which is the time from the second point to the third point, is the attenuation amount (v2), which is the value obtained by subtracting the intensity at the third point from the intensity at the second point. The value divided by t2) is used as the attenuation factor (g2).
The calculation unit calculates the inclination ratio (r), which is the value obtained by dividing the increase rate by the attenuation rate, as the feature amount.
When the inclination ratio is larger than the predetermined inclination ratio threshold value (R2), the determination unit determines that the knock may have occurred in the knock determination as compared with the case where the inclination ratio is smaller than the inclination ratio threshold value. The knock determination device according to any one of claims 1 to 3 , which facilitates high determination. Knock determination devices (29, 31 to In 36),
A waveform obtained based on the detection signal, the vibration waveform representing the time change of the intensity with the strength of the vibration as the intensity, or the time change of the intensity with the absolute value of the intensity of the vibration as the intensity. From the absolute value waveform, of the plurality of maximum points (p) at which the intensity becomes maximum, the second point (p2), which is the maximum point at which the intensity becomes maximum within a predetermined period, and the second point (p2) within the predetermined period. The first point (p1), which is one of the maximum points existing before the two points, and the third point (p1), which is one of the maximum points existing after the second point within the predetermined period. A specific portion (33) that identifies at least three of the maximum points in p3), and
A calculation unit (34) that calculates a predetermined feature amount (t1 to t3, g1, g2, r) using at least the three maximum points, and
Judgment units (35, 36) that perform the knock determination based on the feature amount, and
Have ,
The first time (1st time), which is the time from the first point to the second point, for the increase amount (v1), which is the value obtained by subtracting the strength at the first point from the intensity at the second point. The value divided by t1) is defined as the rate of increase (g1).
The second time (2), which is the time from the second point to the third point, is the attenuation amount (v2), which is the value obtained by subtracting the intensity at the third point from the intensity at the second point. The value divided by t2) is used as the attenuation factor (g2).
The calculation unit calculates the inclination ratio (r), which is the value obtained by dividing the increase rate by the attenuation rate, as the feature amount.
When the inclination ratio is larger than the predetermined inclination ratio threshold value (R2), the determination unit determines that the knock may have occurred in the knock determination as compared with the case where the inclination ratio is smaller than the inclination ratio threshold value. A knock judgment device that makes it easy to judge high. The calculation unit is the time from one to the other of all two adjacent maximum points among the plurality of the maximum points whose intensities exceed a predetermined value (Vc) within the predetermined period. The peak interval (t3) was calculated as the feature amount, and
When the peak interval is larger than the predetermined interval threshold value (T3) , the determination unit determines that the peak interval is smaller than the interval threshold value in the knock determination. The knock determination device according to any one of claims 1 to 5 , wherein the possibility of knocking is low and easy to determine. Knock determination devices (29, 31 to In 36),
A waveform obtained based on the detection signal, the vibration waveform representing the time change of the intensity with the strength of the vibration as the intensity, or the time change of the intensity with the absolute value of the intensity of the vibration as the intensity. From the absolute value waveform, of the plurality of maximum points (p) at which the intensity becomes maximum, the second point (p2), which is the maximum point at which the intensity becomes maximum within a predetermined period, and the second point (p2) within the predetermined period. The first point (p1), which is one of the maximum points existing before the two points, and the third point (p1), which is one of the maximum points existing after the second point within the predetermined period. A specific portion (33) that identifies at least three of the maximum points in p3), and
A calculation unit (34) that calculates a predetermined feature amount (t1 to t3, g1, g2, r) using at least the three maximum points, and
Judgment units (35, 36) that perform the knock determination based on the feature amount, and
Have ,
The calculation unit is the time from one to the other of all two adjacent maximum points among the plurality of the maximum points whose intensities exceed a predetermined value (Vc) within the predetermined period. The peak interval (t3) was calculated as the feature amount, and
When the peak interval is larger than the predetermined interval threshold value (T3) , the determination unit determines that the peak interval is smaller than the interval threshold value in the knock determination. A knock determination device that makes it easier to determine the possibility of knocking. The determination unit includes a shape determination unit (35) that determines the shape pattern to which the vibration waveform or the absolute value waveform belongs based on the feature amount, and a knock determination that performs the knock determination based on the determination by the shape determination unit. The knock determination device according to any one of claims 1 to 7 , further comprising a unit (36). The first point is the maximum point where the intensity first exceeds the predetermined value (Vc) within the predetermined period, and the third point is the last point where the intensity exceeds the predetermined value within the predetermined period. The knock determination device according to any one of claims 1 to 8 , which is the maximum point that has been exceeded. The calculation unit calculates the first time (t1), which is the time from the first point to the second point, as the feature amount.
When the first time is smaller than the predetermined first threshold value (T1), the determination unit may have generated the knock in the knock determination as compared with the case where the first time is larger than the first threshold value. The knock determination device according to claim 9 , which makes it easier to determine the value. The calculation unit calculates the second time (t2), which is the time from the second point to the third point, as the feature amount.
When the second time is larger than the predetermined second threshold value (T2), the determination unit may have generated the knock in the knock determination as compared with the case where the second time is smaller than the second threshold value. The knock determination device according to claim 9 or 10 , which facilitates high determination. The knock determination device according to any one of claims 1 to 11 , further comprising a filter unit (32) for filtering the detection signal with only one type of bandpass filter to obtain the vibration waveform. The knock determination device according to any one of claims 1 to 12 and a control unit (37) that performs knock control for suppressing the occurrence of the knock based on the knock determination by the knock determination device. Knock control device to have.

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