JP3954679B2 - Knock detection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a knocking detection method for detecting a knocking phenomenon occurring in an internal combustion engine.
[0002]
[Prior art]
Conventionally, vibration caused by a knocking phenomenon generated in an internal combustion engine is detected by a vibrometer and a knocking detection signal is output. By passing the knocking detection signal through a filter circuit, low-frequency and high-frequency noise components are removed, A technique is known in which only a knocking frequency component of a specific frequency is allowed to pass, after which only a detection signal at a certain time is taken out through a time gate, and knocking determination is performed based on the magnitude of the waveform of the detection signal. For example, it is as described in Japanese Patent Publication No. 7-13507.
[0003]
[Problems to be solved by the invention]
However, conventionally, a single vibration meter has detected knocking vibrations of a plurality of cylinders, for example, about 3 cylinders to 4 cylinders. Therefore, the distance from each cylinder to the vibration meter is different and is generated in each cylinder. Even if the knocking strength is the same, the magnitude of the signal detected by the vibrometer was different.
In addition, if the magnitude of the load on the engine is different, the magnitude of vibration that occurs when knocking is different, so the signal detected by the vibrometer is not detected even though knocking has occurred. There was a problem that it was determined that knocking did not occur.
Therefore, the present invention detects the knocking vibration of a plurality of cylinders with a single knocking sensor, detects the magnitude of the detection signal between each cylinder uniformly, and evenly vibrates even when the load size is different. It is an object of the present invention to provide a knocking detection method that can detect and make an accurate knocking determination.
[0004]
[Means for Solving the Problems]
The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.
[0005]
According to the first aspect of the present invention, the magnitude of the detection signal of each cylinder is detected uniformly while detecting the vibration due to the knocking phenomenon occurring in the plurality of cylinders of the internal combustion engine by one knocking sensor, and the magnitude of the load is different. A knock detection method that can detect a vibration evenly and perform a knock determination even when the detection signal (8) of one knock sensor passes through only a vibration generated at a specific time, And passing through a filter circuit (15) including a band-pass filter that allows only vibrations of a specific frequency to pass through, and performing a knocking determination using the combustion signal (10) and the knocking signal (9) obtained thereby. The filter circuit (15) is configured to detect knocking vibration using a plurality of sets, and the filter circuit (15) is provided in a plurality. The gate is composed of a combustion part time gate (2a, 2a,...) And a knocking part time gate (2b, 2b,...), And the combustion part time gate (2a, 2a,...) 8), the combustion portion signal (8a) detected at the combustion timing (T1) in front of the occurrence timing of knocking is allowed to pass, and the knocking portion time gate (2b) In (8), only the knocking portion signal (8b) detected at the knocking occurrence time (T2) is allowed to pass, and the combustion portion signal passing through the combustion portion time gate (2a) Passing only the excitation frequency component, the knocking portion signal passing through the combustion portion bandpass filter (3a) and passing through the knocking portion time gate (2b, 2b...) Passes only the knocking frequency component. A representative value of the knocking signal (9) that has passed through the knocking part bandpass filter (3b) and passed through the knocking part time gate (2b) and the knocking part bandpass filter (3b), and the combustion part time gate (2a) ) And a representative value of the combustion signal (10) that has passed through the combustion bandpass filter (3a), and this calculated value is used for knocking determination .
[0006]
The knock detection method according to claim 1, wherein the knocking signal is passed through the knocking part time gate (2b) and the knocking part bandpass filter (3b), the maximum value (A2) of the knocking signal (9), and combustion. The ratio with the maximum value (A2) of the combustion signal (10) that has passed through the part time gate (2a) and the combustion part bandpass filter (3a) is calculated and used as the determination detection value (12) .
[0007]
The knocking detection method according to claim 1, wherein an effective value (B2) of the knocking signal (9) that has passed through the knocking part time gate (2 b) and the knocking part bandpass filter (3 b), and combustion The ratio with the effective value (B1) of the combustion signal (10) that has passed through the part time gate (2a) and the combustion part band-pass filter (3a) is calculated and used as the determination detection value (12 ′) .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described.
[0009]
FIG. 1 is a block diagram showing the overall configuration of the knocking detection method of the present invention, FIG. 2 is a diagram showing the relationship between the crank angle, in-cylinder pressure, and vibration acceleration, and FIG. 3 is a diagram showing the cutoff frequency of the knocking filter. FIG. 4 is a diagram showing the cutoff frequency of the combustion section filter, FIG. 5 is a block diagram showing an embodiment of a method for calculating a determination detection value, and FIG. 6 is a block diagram showing another embodiment.
[0010]
First, the overall configuration of the knocking detection method of the present invention will be described with reference to FIGS.
The vibration due to the knocking phenomenon generated in the internal combustion engine (excluding the diesel engine) detected by the knocking sensor is detected as an analog signal by the knocking sensor, and this detection signal 8 is converted into a digital signal by the A / D converter 1. The
The detection signal 8 converted into a digital signal passes through a time gate that allows only a signal generated at a certain time to pass through, but the time gates are the combustion part time gates 2a, 2a,. 2b...
[0011]
The combustor signal 8a that has passed through the combustor time gates 2a, 2a,... Is then passed through a combustor bandpass filter (hereinafter referred to as “combustor filter”) 3a, where the frequency is lower than a certain frequency. In addition, the high-frequency noise component is removed, and only the combustion signal 10 having a specific frequency passes.
The knocking part signal 8b that has passed through the knocking part time gates 2b, 2b,... Is then passed through a knocking part bandpass filter (hereinafter referred to as “knocking part filter”) 3b, By removing high frequency noise components, only the knocking signal 9 of a specific frequency passes.
[0012]
Then, the combustion signal 10 and the knocking signal 9 that have passed through the combustion part bandpass filter 3a and the knocking part bandpass filter 3b are arithmetically processed by the arithmetic unit 4 and based on a preset knocking determination set value 6. The D / A converter 5 converts the signal into an analog signal, and the determination result is output.
[0013]
The combustion section time gate 2a, the combustion section bandpass filter 3a and knocking section time gate 2b, and the knocking section bandpass filter 3b constitute a set of filter circuits 15 for detection from one cylinder. The signal is passed through a set of filter circuits 15.
In this embodiment, vibration for a plurality of cylinders is detected by one knocking sensor, and one set of filter circuits 15 corresponds to one knocking sensor. By appropriately setting the time gate 2a at the explosion timing of each cylinder, knocking of a plurality of cylinders can be detected. When the number of knocking sensors is three, three sets of filter circuits 15, 15, and 15 are provided. The number of filter circuits 15 is not limited to three, but may be increased or decreased according to the number of knocking sensors.
[0014]
The combustion section time gates 2a, 2a,... Are configured to pass only the combustion section signal 8a detected at the combustion timing T1, which is in front of the timing of occurrence of knocking, among the detection signals 8. The knocking part time gates 2b, 2b,... Are configured to pass only the knocking part signal 8b detected at the knocking occurrence time T2 among the detection signals 8.
Here, FIG. 2 shows a pressure curve 7 representing the relationship between the in-cylinder pressure and the crank angle, and a vibration curve representing the relationship between the vibration acceleration and the crank angle, that is, the detection signal 8. Yes.
The detection signal 8 is classified into a combustion part signal 8a and a knocking part signal 8b depending on the generation time. The combustion part signal 8a is a signal due to vibration caused by a normal combustion phenomenon at the combustion time T1, and the knocking part signal 8b. Is a signal including vibration due to the occurrence of knocking at the knocking occurrence time T2.
[0015]
The knocking portion signal 8b that has passed through the knocking portion time gate 2b is then passed through the knocking portion filter 3b to remove noise components of lower frequency and higher frequency than a certain frequency, and only a detection signal of a specific frequency passes. .
That is, since the frequency of vibration generated by knocking is determined by the diameter (bore) of the cylinder and the combustion temperature, the cut-off frequency FL on the low frequency side of the knocking filter 3b is removed so as to remove frequencies other than this frequency band. And the high frequency side cut-off frequency FH is set.
As shown in FIG. 3, the knocking portion signal 8b passes through the knocking portion filter 3b and becomes a knocking signal 9 including only the frequency component generated by knocking. Further, when knocking does not occur, a knocking signal 9 ′ is obtained, indicating that there is almost no vibration in the frequency band between the frequency FL and the frequency FH at the knocking occurrence time T2.
[0016]
On the other hand, the combustion part signal 8a that has passed through the combustion part time gate 2a is then passed through the combustion part filter 3a to remove low frequency and high frequency noise components from a certain frequency, and only a detection signal of a specific frequency is obtained. pass. That is, the low frequency side cut-off frequency FL ′ of the combustion section filter 3a is passed so that only the frequency component that resonates and excites in the cylinder among the combustion section signal 8a that is a detection signal of vibration generated by combustion is passed. And the high frequency side cut-off frequency FH ′ is set.
As shown in FIG. 4, when the combustion part signal 8a passes through the combustion part filter 3a, both ends of the combustion part signal 8a are cut off to become the combustion signal 10. The low-frequency cut-off frequency FL ′ and the high-frequency cut-off frequency FH ′ change depending on the shape and dimensions of the cylinder. In this embodiment, for example, the frequency FL ′ = 300 Hz and the frequency FH ′ = It is set to 20 kHz. Even if the combustion section filter 3a is not particularly provided, the object of the present case can be achieved.
[0017]
In this way, knocking signal 9 (9 ′) and combustion signal 10 that have passed through filter circuit 15 are subjected to arithmetic processing by arithmetic device 4, a determination detection value is calculated, and the determination detection value is set to knock determination setting value 6 It is compared and judged. An embodiment of a method for calculating the determination detection value will be described with reference to FIG. The detection signal 8 detected by the knocking sensor and converted into a digital signal passes through the combustion part time gate 2a and the combustion part filter 3a to become a combustion signal 10.
Further, the signal passes through the knocking part time gate 2b and the knocking part filter 3b to become a knocking signal 9 (9 '). The maximum value A1 of the combustion signal 10 is measured by the measuring unit 11a of the arithmetic device 4, and the maximum value A2 of the knocking signal 9 (9 ′) is measured by the measuring unit 11b of the arithmetic device 4.
Then, the ratio between the maximum value A1 and the maximum value A2 is calculated. For example, a value obtained by dividing the maximum value A2 by the maximum value A1 (A2 / A1) is obtained as the determination detection value 12, and the determination detection value 12 and the This is compared with the knocking determination setting value 6.
[0018]
Next, another embodiment of the method of calculating the determination detection value will be described with reference to FIG.
The detection signal 8 detected by the knocking sensor and converted into a digital signal passes through the combustion part time gate 2a and the combustion part filter 3a to become a combustion signal 10.
Further, the signal passes through the knocking part time gate 2b and the knocking part filter 3b to become a knocking signal 9 (9 '). The effective value B1 of the combustion signal 10 is measured by the measuring unit 11′a of the arithmetic device 4, and the effective value B2 of the knocking signal 9 (9 ′) is measured by the measuring unit 11′b of the arithmetic device 4. is there.
Then, the ratio between the effective value B1 and the effective value B2 is calculated, and, for example, a value (B2 / B1) obtained by dividing the effective value B2 by the effective value B1 is obtained as the determination detection value 12 ′, and the determination detection value 12 ′ Is compared with a preset knocking determination set value. Thus, representative values such as the maximum value and the effective value of the knocking signal 9 (9 ′) and the combustion signal 10 are measured, the ratio between the two values is calculated, and the knocking determination set value is compared with the determination value. . The representative values of the knocking signal 9 (9 ′) and the combustion signal 10 are not limited to the maximum value or the effective value, and other values may be used.
[0019]
Even if knocking has the same strength, if the distance from the knocking sensor to the cylinder is different or the load on the engine is different, the magnitude of vibration detected by the knocking sensor is different. If the determination is compared with the knocking determination set value, the determination result may be different despite knocking of the same strength.
However, even when knocking has the same intensity and the magnitude of vibration detected by the knocking sensor is different, the ratio between the combustion signal 10 and the knocking signal 9 does not change, so the maximum value A1 and the maximum value A2 are the same. Or the ratio between the effective value B1 and the effective value B2, and the comparison determination with the knocking determination set value can always obtain the same determination result.
As a result, when knocking of the same strength occurs, even if the distance from the knocking sensor to the cylinder is different or the load on the engine is different, the knocking judgment set value and the judgment detection value for comparison judgment are constant. Thus, the same determination result can always be obtained.
[0020]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
According to the first aspect of the present invention, the magnitude of the detection signal of each cylinder is detected uniformly while detecting the vibration due to the knocking phenomenon occurring in the plurality of cylinders of the internal combustion engine by one knocking sensor, and the magnitude of the load is different. A knock detection method that can detect a vibration evenly and perform a knock determination even when the detection signal (8) of one knock sensor passes through only a vibration generated at a specific time, And passing through a filter circuit (15) including a band-pass filter that allows only vibrations of a specific frequency to pass through, and performing a knocking determination using the combustion signal (10) and the knocking signal (9) obtained thereby. A plurality of sets of the filter circuits (15) are configured to detect knocking vibration, and the time gain of the plurality of filter circuits (15) provided is provided. The combustion part time gates (2a, 2a,...) And the knocking part time gates (2b, 2b,...), And the combustion part time gates (2a, 2a,...) 8), the combustion portion signal (8a) detected at the combustion timing (T1) in front of the occurrence timing of knocking is allowed to pass, and the knocking portion time gate (2b) In (8), only the knocking portion signal (8b) detected at the knocking occurrence time (T2) is allowed to pass, and the combustion portion signal passing through the combustion portion time gate (2a) Only the knocking frequency component is allowed to pass through the knocking part signal that has passed through the combustion part bandpass filter (3a) that passes only the excitation frequency component and passed through the knocking part time gate (2b, 2b...). A representative value of the knocking signal (9) passing through the knocking part bandpass filter (3b) and passing through the knocking part time gate (2b) and the knocking part bandpass filter (3b), and the combustion part time gate (2a) And the ratio of the combustion signal (10) that has passed through the combustion section bandpass filter (3a) with the representative value is calculated and used for knocking determination, so that detection signals from a plurality of cylinders can be simultaneously received by different filter circuits. It is possible to process the detection signal according to the distance from each cylinder to the knocking sensor.
[0021]
In addition, the detection signal detected by the knocking sensor depends on the generation time, the combustion part signal that is a signal due to vibration caused by a normal combustion phenomenon at the combustion time, and the knocking that is a signal including vibration due to the occurrence of knocking at the knocking generation time It was possible to distinguish it from the part signal.
In addition, it is possible to extract only a component necessary for knocking determination, such as a knocking signal including only a frequency component generated by knocking (a frequency component that resonates and vibrates in a cylinder) and a combustion part signal.
[0022]
Further, even when knocking has the same intensity and the magnitude of vibration detected by the knocking sensor is different, the ratio between the combustion signal 10 and the knocking signal 9 does not change, so the distance from the knocking sensor to the cylinder is different. Even if the load applied to the engine is different, a constant value is obtained as the determination detection value for performing the comparison determination with the knocking determination set value, and the same determination result can always be obtained.
[0023]
Since it is configured as in claims 2 and 3, the ratio of the combustion signal 10 and the knocking signal 9 does not change even when knocking of the same strength is performed and the magnitude of vibration detected by the knocking sensor is different. Therefore, if the ratio between the maximum value A1 and the maximum value A2 is calculated or the ratio between the effective value B1 and the effective value B2 is calculated and compared with the knocking determination set value, the same determination result is always obtained. It can be done.
As a result, when knocking of the same strength occurs, even if the distance from the knocking sensor to the cylinder is different or the load on the engine is different, the knocking judgment set value and the judgment detection value for comparison judgment are constant. Thus, the same determination result can always be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the overall configuration of a knocking detection method of the present invention.
FIG. 2 is a diagram showing a relationship between a crank angle, in-cylinder pressure, and vibration acceleration.
FIG. 3 is a diagram illustrating a cutoff frequency of a knocking filter.
FIG. 4 is a diagram showing a cutoff frequency of a combustion section filter.
FIG. 5 is a block diagram illustrating an embodiment of a method for calculating a determination detection value.
FIG. 6 is a block diagram showing another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 A / D converter 2a Combustion part time gate 2b Knocking part time gate 3a Combustion part bandpass filter 3b Knocking part bandpass filter 4 Arithmetic unit 8 Detection signal 8a Combustion part signal 8b Knocking part signal 9/9 'Knocking signal 10 Combustion Signal 12 Determination detection signal 15 Filter circuit

Claims (3)

While detecting the vibration caused by the knocking phenomenon that occurs in multiple cylinders of an internal combustion engine with a single knocking sensor, the magnitude of the detection signal of each cylinder is detected uniformly, and even if the load is different, the vibration is even. Is a knocking detection method capable of detecting knocking and performing a knocking determination, wherein a detection signal (8) of one knocking sensor passes only a vibration generated at a specific time and only a vibration at a specific frequency. Is passed through a filter circuit (15) that is a set of a band-pass filter that passes the filter, knocking determination is performed using the combustion signal (10) and the knocking signal (9) obtained thereby, and the filter circuit (15 ) To detect knocking vibration, and the time gate of the plurality of filter circuits (15) provided at the time of the combustion section It comprises a gate (2a, 2a ...) and a knocking part time gate (2b, 2b ...), and the combustion part time gate (2a, 2a ...) knocks out of the detection signal (8). The combustion portion signal (8a) detected at the combustion timing (T1) in front of the occurrence timing of the engine is allowed to pass, and the knocking portion time gate (2b) includes the detection signal (8) Only the knocking part signal (8b) detected at the knocking occurrence time (T2) is allowed to pass, and the combustion part signal that has passed through the combustion part time gate (2a) is converted into only the excitation frequency component in the cylinder. A knocking section bar that passes only the knocking frequency component of the knocking section signal that has passed through the combustion section bandpass filter (3a) to be passed and passed through the knocking section time gate (2b, 2b...). A representative value of the knocking signal (9) passing through the depass filter (3b) and passing through the knocking part time gate (2b) and the knocking part bandpass filter (3b), the combustion part time gate (2a) and the combustion A knocking detection method characterized by calculating a ratio of the combustion signal (10) passing through the partial bandpass filter (3a) to a representative value and using the calculated value for knocking determination . The knocking detection method according to claim 1, wherein a maximum value (A2) of the knocking signal (9) passing through the knocking part time gate (2b) and the knocking part bandpass filter (3b), and a combustion part time gate (2a). And a knocking detection method characterized by calculating a ratio of the combustion signal (10) that has passed through the combustion section bandpass filter (3a) to the maximum value (A2) to obtain a determination detection value (12) . The knocking detection method according to claim 1, wherein an effective value (B2) of the knocking signal (9) passing through the knocking part time gate (2b) and the knocking part bandpass filter (3b), and a combustion part time gate (2a). And the knocking detection method characterized by calculating ratio with the effective value (B1) of the combustion signal (10) which passed the combustion part band pass filter (3a), and making it a determination detection value (12 ') .

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