JP6855982B2 - Knocking judgment device - Google Patents

Description

The present invention relates to a knocking determination device that determines whether or not knocking has occurred in an internal combustion engine based on an output signal of a knocking sensor.

For example, in Patent Document 1 below, whether or not knocking occurs based on whether or not a plurality of frequency components are extracted from the time series data of the output signal of the knocking sensor and the intensity of the time series data of each frequency component is equal to or higher than the threshold value. A knocking determination device for determining the frequency is described. Specifically, in this device, each frequency component is binarized as "1" when the intensity is equal to or more than the threshold value and as "0" when the intensity is less than the threshold value, and each frequency component and each phase in the time series. In addition, the product of the binarized time series data and the master pattern data when knocking occurs is calculated, and the product is integrated. Then, when the integrated value is large, it is determined that knocking has occurred.

JP-A-2009-257316

By the way, in the case of the above-mentioned determination device, when all the binarized time series data are "1", the knocking is performed because the above-mentioned integrated value becomes large even though the similarity with the master pattern data is low. May be determined to have occurred.

In order to solve the above problem, in a knocking determination device that determines whether or not knocking has occurred in the internal combustion engine based on the output signal of the knocking sensor, a plurality of frequency components different from each other from the time series data of the output signal of the knocking sensor. The filter process for extracting the above frequency components, the length calculation process for calculating the length of the continuation section in which each of the plurality of frequency components is equal to or greater than the threshold value corresponding to the frequency component, and the respective frequency components. Based on the comparison process for comparing the lengths of the continuation sections and the comparison result, the length of the continuation section of one of the plurality of frequency components is higher than that of the frequency component. On the condition that it is longer than the length of the continuation section, the determination process of determining that knocking has occurred is executed.

As for the frequency component of vibration caused by knocking, the lower the frequency, the longer the intensity tends to be. Therefore, in the above configuration, the lengths of the continuation sections of the plurality of frequency components of the vibration accompanying knocking are compared by the comparison process, and it is determined that knocking has occurred based on the comparison result. For this reason, compared to the case where the comparison process is not executed, knocking is determined with high accuracy while determining whether or not the low frequency has a tendency to continue for a long time with high intensity, and as a result, knocking is performed with high accuracy. It can be determined.

The figure which shows the knocking determination apparatus and the internal combustion engine which concerns on one Embodiment. The flow chart which shows the procedure of the process which determines whether or not the knocking which concerns on this embodiment occurs. A time chart showing the transition of the intensity of the noise of the PCV valve for each frequency component. A time chart showing the transition of the intensity of the sliding noise of the piston ring for each frequency component. A time chart showing the transition of the intensity for each frequency component when knocking occurs.

Hereinafter, an embodiment of the knocking determination device will be described with reference to the drawings.
A throttle valve 14 for adjusting the cross-sectional area of the flow path is provided in the intake passage 12 of the internal combustion engine 10 shown in FIG. 1, and a fuel injection valve 16 is provided downstream of the throttle valve 14. The air sucked into the intake passage 12 and the fuel injected by the fuel injection valve 16 are partitioned by the cylinder 22 and the piston 24 provided with the piston ring 24a as the intake valve 18 opens. It flows into the combustion chamber 26. An ignition device 28 is exposed in the combustion chamber 26, and a mixture of fuel and air is used for combustion by spark discharge by the ignition device 28. The combustion energy of the air-fuel mixture is converted into the rotational energy of the crankshaft 30 via the piston 24. The air-fuel mixture used for combustion is discharged to the exhaust passage 34 as exhaust gas when the exhaust valve 32 is opened.

The crankcase 36 is connected to the intake passage 12 by the PCV passage 40. The PCV passage 40 is provided with a mechanical check valve (PCV valve 42) that opens when the pressure on the crankcase 36 side becomes higher than the pressure on the intake passage 12 side by a predetermined pressure or more.

The control device 50 targets the internal combustion engine 10, and in order to control the control amount (torque, exhaust component, etc.), the operation unit of the internal combustion engine 10 such as the throttle valve 14, the fuel injection valve 16, and the ignition device 28 is controlled. Manipulate. The control device 50 refers to the output signal Scr of the crank angle sensor 60 and the output signal Sn of the knocking sensor 62 when controlling the control amount. The control device 50 includes a CPU 52 and a ROM 54, and the CPU 52 executes a program stored in the ROM 54 to control the control amount. Further, the CPU 52 determines knocking when controlling the control amount, and operates the ignition timing of the ignition device 28 based on the determination.

FIG. 2 shows a procedure for processing related to determining whether or not knocking according to the present embodiment has occurred. The process shown in FIG. 2 is realized by the CPU 52 repeatedly executing the program stored in the ROM 54, for example, at a predetermined cycle.

In the series of processes shown in FIG. 2, the CPU 52 first acquires the time-series data of the vibration intensity D, which is the time-series data of the output signal Sn of the knocking sensor 62 (S10). In the present embodiment, the time series data of the vibration intensity D for each 5 ° CA is acquired for the section of the crank angle θ calculated based on the output signal Scr and having a length of 90 ° CA. Next, the CPU 52 calculates a shape correlation coefficient that quantifies the correlation between the transition of the vibration intensity D and the transition of the intensity when knocking occurs (S12). Specifically, the CPU 52 calculates the shape correlation coefficient according to the degree of similarity between the damping rate of the intensity when knocking occurs and the damping rate of the vibration intensity D. Next, the CPU 52 calculates the integrated intensity S obtained by integrating the vibration intensity D for each 5 ° CA over the section of 90 ° CA (S14).

Next, the CPU 52 executes a bandpass filter process on the time-series data of the vibration intensity D with four frequencies f1, f2, f3, and f4 that are different from each other as the center frequencies (S16). Here, "f1 <f2 <f3 <f4". As a result, the vibration intensity D1 of the frequency component having the frequency f1 as the central frequency, the vibration intensity D2 of the frequency component having the frequency f2 as the central frequency, the vibration intensity D3 of the frequency component having the frequency f3 as the central frequency, and the frequency f4 Time-series data over 90 ° CA for every 5 ° CA is generated with the vibration intensity D4 of the frequency component centered on.

Next, the CPU 52 calculates the lengths L1, L2, L3, L4 of the continuation section in which the vibration intensities D1, D2, D3, and D4 are larger than the corresponding threshold values D1th, D2th, D3th, and D4th (S18). .. Here, the CPU 52 variably sets the threshold values D1th, D2th, D3th, and D4th to a value larger when the vibration intensity (background noise intensity) when knocking does not occur is larger than when the vibration intensity is small. This is in view of the fact that when the rotation speed of the crankshaft 30 is high, the vibration generated in the internal combustion engine 10 is larger than when the rotation speed is low. Since the vibration intensity changes when knocking does not occur, it is determined that knocking has occurred on the condition that vibration with a relatively large intensity is generated with respect to the vibration intensity at that time when knocking does not occur. Therefore, the above variable setting process is executed. The variable setting process may be, for example, a process of detecting background noise based on the vibration intensity D and variably setting the threshold values D1th, D2th, D3th, and D4th based on the detection. Further, for example, the threshold values D1th, D2th, D3th, and D4th may be variably set by inputting the rotation speed NE and the load of the internal combustion engine 10, and the value variably set based on the rotation speed NE and the load may be detected background noise. It may be corrected based on.

Next, the CPU 52 calculates the frequency-specific integrated intensities S1, S2, S3, and S4, which are the integrated values of the 90 ° CA sections of the vibration intensities D1, D2, D3, and D4 (S20).
Next, the CPU 52 determines whether or not the shape correlation coefficient is larger than a predetermined value (S22). Then, when the CPU 52 determines that it is larger than the predetermined value (S22: YES), the CPU 52 determines whether or not the integrated strength S is larger than the predetermined value Sth (S24). Here, the CPU 52 variably sets the predetermined value Sth to a larger value when the intensity of the background noise is large than when it is small, for the same reason as the reason for variably setting the threshold value D1th or the like.

When the CPU 52 determines that it is larger than the predetermined value Sth (S24: YES), each of the frequency-specific integrated intensities S1, S2, S3, and S4 is larger than each of the corresponding predetermined values S1th, S2th, S3th, and S4th. Whether or not it is determined (S26). Here, for the same reason as the reason for variably setting the threshold value D1th or the like, the CPU 52 variably sets the predetermined values S1th, S2th, S3th, S4th to a larger value than when the background noise intensity is large and small.

When the CPU 52 determines that it is larger than each of the predetermined values S1th, S2th, S3th, and S4th (S26: YES), the lengths L1, L2, L3, and L4 of the above sections are compared, and the length corresponding to the low frequency is increased. It is determined whether or not there is a tendency to be long (S28). Specifically, based on the relationship of "L1> L2> L3> L4", which tends to be longer as the frequency is lower, the frequencies of the lengths L1, L2, L3, and L4 are adjacent to each other with respect to the relationship. Allows two specific magnitude relationships to be reversed. However, the "reversal" here includes the case where there is no magnitude relationship between the two, that is, the case where they are equal to each other.

In the CPU 52, the relationship of "L1> L2> L3> L4" is established, or two specific magnitude relationships of lengths L1, L2, L3, and L4 whose frequencies are adjacent to each other are reversed with respect to the relationship. If (S28: YES), it is determined that knocking has occurred because the length corresponding to the low frequency tends to be longer (S30).

The CPU 52 temporarily ends a series of processes shown in FIG. 2 when the process of S30 is completed or when a negative determination is made in the processes of S22, S24, S26, and S28.
Here, the operation of the present embodiment will be described.

FIG. 3 shows the transition of the intensity of each frequency component of noise accompanying the opening and closing of the PCV valve 42, and FIG. 4 shows each frequency component of noise generated when the piston ring 24a slides on the inner wall surface of the cylinder 22. Shows the transition of the intensity of. The noise associated with the opening and closing of the PCV valve 42 shown in FIG. 3 is caused by the fact that the pressure on the crankcase 36 side fluctuates in the vicinity of the pressure higher than the pressure on the intake passage 12 side by the predetermined pressure. When the noise shown in FIG. 3 or the noise shown in FIG. 4 occurs, a positive judgment can be made in all the processes of S22, S24, and S26. Therefore, it is not possible to determine with high accuracy whether or not knocking has occurred only by the processing of S22, S24, and S26. In particular, as the compression ratio of the combustion chamber 26 is set to be increased, the friction between the piston ring 24a and the inner wall surface of the cylinder 22 is set to be large, and the intensity of noise generated when sliding is increased. Becomes serious.

Therefore, in the present embodiment, the CPU 52 determines that knocking has occurred on condition that the affirmative determination is made by the process of S28. This is because, as shown in FIG. 5, when knocking occurs, the lower the frequency, the longer the continuous section in the state where the vibration intensity is large. In the case of the intensity distributions of the various noises illustrated in FIGS. 3 and 4, since there is no tendency shown in FIG. 5, it is highly determined whether or not knocking has occurred by making a positive judgment by the processing of S28. It can be judged with accuracy.

<Correspondence>
The correspondence between the matters in the above embodiment and the matters described in the above-mentioned "means for solving the problem" column is as follows. The knocking determination device corresponds to the control device 50, the filter process corresponds to the process of S16, the length calculation process corresponds to the process of S18, the comparison process corresponds to the process of S28, and the determination process corresponds to the process of S28. , S30.

<Other Embodiments>
In addition, at least one of each item of the said embodiment may be changed as follows.
-The processing of S26 is changed, and instead of determining whether each of the integrated frequencies S1, S2, S3, and S4 is larger than each of the predetermined values S1th, S2th, S3th, and S4th, the integrated intensity by frequency is determined. It may be a process of determining whether or not a part of S1, S2, S3, and S4 is larger than the corresponding predetermined values S1th, S2th, S3th, and S4th.

-The process of S28 may be changed to determine whether or not "L1> L2> L3> L4". Further, for example, whether or not any of "L1> L2> L3> L4", "L1 ≥ L2> L3> L4", "L1> L2 ≥ L3> L4", and "L1> L2> L3 ≥ L4" is applicable. May be determined.

-The plurality of frequency components are not limited to four, and may be, for example, two, three, or five or more.
-At least one of the processes of S22, S24, and S26 may be deleted.

-In the above embodiment, it has been illustrated that the noise associated with the opening and closing of the PCV valve 42 and the noise associated with the sliding of the piston ring 24a are separated from the knocking, but the present invention is not limited to this. For example, when the internal combustion engine 10 includes various actuators such as an actuator that changes the valve opening timing of the intake valve 18, noise and knocking due to the operation may be separated.

10 ... Internal combustion engine, 12 ... Intake passage, 14 ... Throttle valve, 16 ... Fuel injection valve, 18 ... Intake valve, 22 ... Cylinder, 24 ... Piston, 24a ... Piston ring, 26 ... Combustion chamber, 28 ... Ignition device, 30 ... Cylinder shaft, 32 ... Exhaust valve, 34 ... Exhaust passage, 36 ... Crankcase, 40 ... PCV passage, 42 ... PCV valve, 50 ... Control device, 52 ... CPU, 54 ... ROM, 60 ... Crank angle sensor, 62 ... Knocking sensor.

Claims (1)

In a knocking determination device that determines whether or not knocking has occurred in an internal combustion engine based on the output signal of the knocking sensor.
Filter processing that extracts a plurality of different frequency components from the time series data of the output signal of the knocking sensor, and
A length calculation process for calculating the length of a continuation section in which each of the plurality of frequency components is equal to or greater than a threshold value corresponding to the frequency component.
A comparison process for comparing the lengths of the continuation sections of the plurality of frequency components, and
Based on the comparison result by the comparison process, the length of the continuation section of one of the plurality of frequency components is longer than the length of the continuation section of the frequency component having a frequency higher than that of the frequency component . On the condition that the logical product with the predetermined condition is true, the determination process of determining that knocking has occurred and the determination process are executed.
The predetermined conditions are a condition that the integrated strength, which is an integrated value of the vibration intensity based on the output signal, is larger than the predetermined value, and a condition that the integrated value of each intensity of the plurality of frequency components is larger than the predetermined value. A knocking determination device including at least one of the two conditions.

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