JP3153394B2 - Knock detection method for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting knocking of an internal combustion engine and an ignition timing control method using the same, and more particularly to a method for reducing erroneous detection of knocking due to a change in an operating state of the internal combustion engine.

[0002]

2. Description of the Related Art As is well known, knocking is a phenomenon in which the gas in a combustion chamber vibrates due to the self-ignition of unburned gas at the end of the combustion chamber, and this vibration is transmitted to the engine body.

[0003] Since this knocking causes a loss of generated energy of the engine (output reduction), an impact on each part of the engine, and a reduction in fuel consumption, it is desirable to avoid knocking as much as possible. Accurate detection is essential. Under such a request, for example, as described in Japanese Patent Application Laid-Open No. 58-52020, only a resonance frequency component in the range of 5 to 12 kHz is separated from the output signal of the vibration detection sensor using a band-pass filter. And
A method of detecting the occurrence of knocking based on whether or not the integrated value of the output has become larger than the background level, or as described in JP-A-3-47449, a plurality of resonance frequency components are extracted to perform knocking. There was a method of performing detection.

By the way, the background level is
For example, as shown in Expressions ₁ and 2, a weighted average of the previous background level BGL ₁ and the output signal of the current vibration detection sensor f ₁ , or the output f ₂ of the previous vibration detection sensor and the current vibration obtained by a weighted average of the output of the detection f ₁ sensor.

[0005]

BGL = kBGL ₁ + (1−k) f ₁ (Equation 1)

[0006]

BGL = kf ₁ + (1−k) f ₂ (Equation 2) k: Constant Therefore, the above-described technique is used in a transient state such as acceleration.
As shown in FIG. 9, a delay in following the background level occurs, and during the transition, the calculated background level value is smaller than the target background level value. There is a problem that the possibility of erroneous detection of knocking due to an increase in the N ratio increases.

As a technique for solving this problem, for example, as disclosed in Japanese Patent Application Laid-Open No. 3-124951, the background level is always learned and stored for each operating area, and the operating area for detecting knocking is controlled. At the time of entry or transition, a method of performing knocking determination using the learned and stored background level instead of the calculated background level has been proposed.

[0008]

However, in the above-mentioned prior art, since the knocking determination is performed using the learned background level as it is, the learned value is lower than the required background level at the time of entry. If the value is learned, erroneous determination of knocking may occur.

[0009]

According to SUMMARY OF THE INVENTION The present invention, above problems is provided in the vicinity of the combustion chamber internal combustion engine, comprising a combustion state detection means for detecting the combustion state of the internal combustion engine, the fuel <br / Extracting a characteristic component related to knocking from the state signal of the burning detection means, calculating a comparison component serving as a reference for knocking determination based on the state signal, and determining knocking based on the characteristic component and the comparison component. Internal combustion engine
In the knocking detection method, only performs the operation of said comparison components with <br/> specific operation region is a knock control region retains calculation value of said comparison components in separation of the specific region,
At the time of re-entry of the specific operation region, the value of the held comparison component is compared with a predetermined comparison component reference value that is a reference value of the comparison component of the specific operation region, and the larger value is set to the larger value. The problem can be solved by setting the initial value of the comparison component at the time of entry and calculating the comparison component and determining knocking based on the initial value.

[0010]

According to the present invention, the learned and held background level is compared with a reference background level, and the higher background level is set in a specific operation area (hereinafter, referred to as a knock control area). Since the initial value of the background level at the time of entry is set, the initial value can be set to an appropriate value, and erroneous determination of knocking can be reduced. Further, since the reference value is learned and a limit value is provided for the learned value, it is possible to suppress the reference value from becoming an abnormal value.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

First, the principle of determining whether or not knocking has occurred in the present invention will be described. The vibration of the engine contains many vibration components. For example, vibration components due to piston friction, crankshaft rotation, valve operation, and the like. Further, these vibration components change depending on the engine state.

When knocking occurs in the engine, vibration peculiar to knocking occurs. The determination as to whether knocking has occurred is made by separating the vibration specific to knocking from the overall vibration of the engine detected by the vibration sensor.

FIG. 4 is a diagram showing an analysis result of a frequency component of an output of the vibration sensor when knocking does not occur. On the other hand, FIG. 5 is a diagram illustrating an analysis result of a frequency component of an output of the vibration sensor when knocking occurs.

As can be seen by comparing FIGS. 4 and 5, when knocking occurs, each characteristic component, that is, the resonance frequency component becomes larger than when knocking does not occur. I can understand that

Next, with reference to FIGS. 6 and 7, a description will be given of the determination of the presence / absence of knocking using the knocking determination index. In order to explain the principle operation, the resonance frequency f ₁₀
(For example, 6.3 KHz) and f ₀₁ (for example, 13.0 KHz)
A description will be given using the frequency components of FIG. However, the present invention is not limited to this, and it is possible to determine whether knocking has occurred using any two or more resonance frequency components.

The vibration sensor detects vibration by combining knocking vibration and vibration including background vibration.
Therefore, knocking determination index I is determined include vibration I _k due to the occurrence of background vibration I _b and knocking when index I _b becomes defined in the background vibration, the knocking occurs when a knocking has not occurred Is the index I to be obtained.

The above knocking determination index I is expressed by the following equation using a main resonance frequency component.

I = ω ₁₀ P (f ₁₀ ) + ω ₂₀ P (f ₂₀ ) + ω ₀₁ P (f ₀₁ ) + ω ₃₀ P (f ₃₀ ) + ω ₁₁ P (f ₁₁ ) where ω is determined by the engine speed. Take a real value. In addition, it can take two values of 1 or 0. P is the vibration intensity (power spectrum) of each resonance frequency component.

The index I _k indicated by the resonance frequency component of the vibration due to knocking determination index I _b and knocking generation indicated by the resonance frequency component of the background vibration as shown in FIG. 6 are different in direction and magnitude . This is because, as is clear from a human auditory test, the engine sound in the case of no knock can be distinguished from the engine sound in the case of knock by a crisp sound, for example, and the timbre differs depending on the presence or absence of knock.

When the vibration due to the occurrence of knocking is added to the background vibration, the knock determination index I based on the f ₀₁ and f ₁₀ components included in the vibration sensor enters a region below the knock determination threshold I ₀₁ in the case of FIG. , also it is possible to determine the presence of knock by exiting to the outside of the threshold value I ₀₂ in FIG.

In the present specification, not only the five terms on the right side of the equation (1) but also any combination of a plurality of resonance frequency components included in the output of the vibration sensor is defined as a knock index. .

As described above, when the knock determination index is used, the configuration of a specific frequency component due to the occurrence of knocking with respect to the background vibration is taken into consideration, so that the presence or absence of knocking can be determined even when the background vibration increases. .

Hereinafter, a method of detecting knocking, which is central to the present invention, will be described in detail.

FIG. 8 shows the vibration intensity (power spectrum) for each frequency. The case where knocking occurs is shown by a solid line, and the case where knocking does not occur is shown by a broken line. It can be seen that the vibration intensity in each resonance frequency band is large.

In the present invention, the above-mentioned knock index is obtained from the ratio of the vibration intensity with and without knocking (S / N ratio). The vibration intensity without knocking (background level) is determined for each detection frequency. It is created by averaging processing based on knock frequency components detected in the past.

For this reason, when the mechanical noise increases due to a sudden change in the engine speed such as in a transient operation state, or when the vibration intensity suddenly changes without knocking due to an increase in combustion vibration due to a sudden change in the engine load, the background level becomes the latest knock frequency component value. Therefore, there is a risk of erroneous knocking determination shown in FIG.

Knock control is often defined only in a specific region determined by the engine speed and engine load. In this case, the background level smoothing process is performed only in the specific knock control region. Irrespective of the processing method. Both of these will be described with reference to FIG.

In the former method, the background level at the time of the previous departure from the knock control area is set as it is as the initial value of the background level at the time of re-entering the knock control area. If the initial value of the background level at this time is abnormally high, the background level during the transition quickly converges to the target value, but knocking is hardly detected until the background level converges to the target value. Become. In the latter method, since the background level at the time of entering the knock control region is near the target value, knocking can be detected with high accuracy, but the tracking performance deteriorates during transition, and the background level quickly converges to the target value. become unable.

As described above, since the two have contradictory characteristics, the background level is smoothed in such a manner that the respective characteristics of the two are utilized and the respective disadvantages are canceled out. Processing must be performed.

Therefore, in the present invention, the background level smoothing process is limited to the knock control region, and the background level is converged from an appropriate high value to improve the followability of the background level even during the transient operation, thereby causing erroneous determination. And the knock controllability at the time of entering the knock control area can be ensured.

First, the operation of the CPU for determining the occurrence of knocking will be described with reference to FIG.

In FIG. 1, this flowchart is executed for each explosion cycle, and is started by interrupting the CPU.

At step 140, it is determined whether or not the current operation state is within the knock control region. If it is within the region, the process proceeds to step 141, and if it is outside the region, knock control is not performed. This knock control area determination is performed in step 1
02, 105, 106, etc., may be set.

In step 141, it is determined whether or not the vehicle was in the knock control region at the time of the previous explosion cycle, that is, it is determined that the vehicle has entered the knock region, and it was determined that the vehicle was also in the knock region and was continuously in the knock region last time. If so, step 1
In step 142, if it is determined that the previous time is outside the knock control area and it is time to enter the knock area, in step 142, BGLi is set to an initial value BGLINTi previously set in the memory, and the flow proceeds to step 101. In step 101, an A / D converted value obtained by converting the output signal from the vibration sensor by the A / D converter is taken in.

Next, at step 102, the frequency of the A / D converted signal of the vibration sensor is analyzed. This frequency analysis is performed by a method such as a fast Fourier transform or a Walsh Fourier transform.

Thereafter, among the signals subjected to the frequency analysis in step 103, n frequency bands including the resonance frequency are selected. In this embodiment, eight resonance frequencies are selected.

When a frequency is selected in step 103,
Next, in step 104, the S / N ratio representing the vibration intensity is determined for each selected frequency.

That is, a plurality of selected frequencies (f1... F
n) and the background level (BGL1... BGLn) of the frequency corresponding thereto are determined, and the S / N for each frequency is determined.
The ratio SLi = fi / BGLi is determined.

Therefore, in this embodiment, SL1 = f1 / B
GL1,..., SLi = fn / BGLn are obtained.

Step 132 is a counter, which is incremented by one each time the S / N ratio of one selected frequency is calculated once. In step 133, it is determined whether or not the value of the counter value i is equal to the selected number n, for example, 8. If n = i,
Proceed to step 105, and if n> i, step 129
Then, the above determination is repeated until all the S / N ratios of the selected frequency are calculated.

Next, at step 105, m of the selected frequencies are extracted in ascending order of S / N ratio, and in this embodiment, five are extracted to determine the knock intensity. The equation for determining this knock strength is, for example,

[0043]

(Equation 3)

It is obtained by adding the S / N ratio as expressed by

When the knock intensity is obtained, a predetermined value for knock determination is compared with the knock intensity obtained in step 105 in step 106, and knocking occurs when it is determined that the knock intensity obtained in step 105 is large. In step 107, knocking is detected.

Thereafter, at step 108, a knock flag indicating occurrence of knocking is set to "1". The knock flag is used in a separately started ignition control task.

On the other hand, if it is determined in step 106 that the knock intensity is smaller than the predetermined value, it is determined that knocking has not occurred, and in step 109 each background level BGL is determined.
It is determined whether i is greater than a predetermined limit value, here a lower limiter BGLMTi. In this embodiment, BGL1
BGLMT1 is compared with BGLMT1.

If it is determined in step 109 that the background level is larger than the lower limiter BGLMTi, that is, if it is determined that the background level is normal, the background level BGLi is updated in step 110.

The updating of the background level BGLi is obtained by filtering the vibration intensity of the selected frequency. Specifically, BGL for each selected frequency
i = BGLi × (1−α) + fi × α.

Conversely, in step 109, it is determined that the background level BGLi is smaller than the lower limiter BGLMTi, that is, if it is determined that the background level is abnormal, the limiter value is set and used as the BGLi in the next step 104.

Further, a lower limiter fLMTi of the selected frequency fi is provided at a stage preceding the step 104 to suppress an abnormal value input.

In step 129, it is determined whether or not the intensity is greater than or equal to a predetermined lower limiter fLMTi for each frequency fi. If it is determined that the value is larger or equal, the process proceeds to step 104, and the normal S / S
Perform N ratio calculation.

On the other hand, if it is determined in step 129 that the intensity of each frequency fi is smaller than the predetermined lower limiter fLMTi, the process proceeds to step 130, where the intensity of the frequency fi and the S / N ratio of the background level are set to 1. . That is,
A process is performed to determine that knocking has not occurred for the corresponding frequency.

Next, at step 131, the intensity of the corresponding frequency is replaced with a predetermined lower limiter fLMTi, and the routine proceeds to step 105, where the knock intensity is calculated.

This processing solves the problem that the S / N ratio abnormally increases due to a quantization error that occurs when the intensity of each frequency abnormally decreases by setting a lower limiter for the frequency intensity.

Here, the lower limiter fLMTi of each frequency fi in step 129 and the lower limiter BGLMTi of the background level in step 109 may be used in combination, or only one of them may be employed.

Next, at step 112, the knock flag is set to "0".

The knock detection routine ends with the above processing, and the knock flag set in this routine is used in the ignition control task. Note that the lower limiter is shared with the threshold for determining the background level, but may be provided separately.

The knock generation signal obtained as described above is used in the ignition control task described below, and will be described.

FIG. 10 is a system configuration diagram of the ignition device. Air enters through the inlet of the air cleaner 1, passes through the dust 3, the throttle body 5 having a throttle valve, and the intake cylinder 6, and is sucked into the cylinder of the engine 7. The intake air amount is detected by a hot-wire type air flow meter provided in the duct 3, and a detection signal is input to the control unit 9.

On the other hand, fuel is injected from a fuel tank (not shown) through an injector 16, mixed with intake air in an intake passage, and supplied to a cylinder of the engine 7.
The air-fuel mixture is compressed by the engine 7 and discharged from the exhaust pipe 8 after the explosion ignited by the ignition flag 15. Exhaust pipe 8
Is provided with an exhaust sensor 11, and a detection signal is input to the control unit 9.

The high voltage generated by the ignition coil 13 is distributed to each cylinder by the distributor 14 and supplied to the ignition plug 15. The rotation state of the engine is detected by a crank angle sensor 12, and the crank angle sensor 12 outputs a Ref signal indicating an absolute position for each rotation and a P _OS signal indicating a position shifted by a predetermined angle from the absolute position. The Ref signal and the P _OS signal are input to the control unit 9. A vibration sensor 151 for detecting vibration is attached to the engine 7, and a detection signal is input to the control unit 9.

The control unit 9 calculates the fuel supply amount and the ignition timing based on the signals from the sensors, and outputs control signals to the injector 16 and the ignition coil 13. FIG. 11 is a diagram showing details of the control unit 9. The control unit 9 is a CPU 20, an A / D
Converter 21, ROM 22, input I / O 23, RAM 2
4, a control block 34 composed of DPRAM 25, output I / O 26 and bus 37, CPU 29, port 2
7, timing circuit 28, A / D converter 30, ROM3
1, a RAM 32, a clock 33, an operational circuit 38, and a knocking detection block 35 composed of a bus 36. Here, CPU 20, CPU
Exchange of data of 29 is DPRA which is dual port RAM
Made through M25.

[0064] hot-wire flow meter 2 intake air amount Q _a detected by is converted into a digital value by the A / D converter 21, are incorporated into CPU 20. The Ref signal and the P _OS signal detected by the crank angle sensor 12 are taken into the CPU 20 through the input I / O 23. C
The PU 20 performs arithmetic processing according to a program stored in the ROM 22, and the arithmetic result is obtained from the output I / O 26 as a fuel injection time signal Ti indicating an amount of fuel injection and an ignition timing signal θig.
n to each actuator. Necessary data holding during the arithmetic processing is performed by the RAM 24.

On the other hand, the timing circuit 28 determines that the operation circuit 37 has a TDC indicating a top dead center (Top Dead Center).
When a signal is generated, the sampling signal is generated by dividing the frequency of the periodic signal generated by the clock 33 in accordance with the contents input to the port 27 by the CPU 20. When the sampling signal is generated, the A / D converter 30 converts the output signal P of the vibration sensor 151 into a digital value.

A conventional vibration sensor for detecting knocking resonates at around 13 KHz. In this embodiment, a vibration sensor that resonates at 18 KHz or more is used in order to obtain a resonance frequency component of at least 18 to 10 KHz. ing.

The CPU 29 converts the digital value sampled according to the program held in the ROM 31 into RA
The frequency analysis is performed based on the data stored in the M32 and based on the stored data as shown in FIG. 1 to determine whether knocking has occurred. The result of the determination as to whether or not knocking has occurred is sent to the CPU 20 via the DPRAM 25.
Conveyed to.

Next, the operation of the CPU 20 for calculating the ignition timing will be described with reference to the flowchart of FIG. The operation of this flowchart is started at regular time intervals, for example, every 10 msec. In step 201, the engine speed N and the intake air amount Q are read from predetermined registers set in the RAM 24. In step 202, the intake air amount Q / N per unit rotation speed is calculated, the fuel injection time width Ti is obtained from the Q / N, and the basic ignition timing is obtained from the basic ignition timing map stored in the ROM 22 for fuel supply. Timing θ
Find base. In step 203, it is determined whether knocking has occurred based on the content of the knock flag (knockflag) determined according to the flowchart shown in FIG. If knocking has occurred, at step 213 the ignition timing θad
The predetermined retard amount Δθret is subtracted from v. The ignition timing is retarded by this subtraction. In step 214, the ignition timing delayed by knocking is compared with a predetermined rotation, for example, 50 (step 2).
In step 05), the base to be recovered is determined. The count data A is initialized, and the process proceeds to step 208.

On the other hand, if knocking has not occurred in step 203, the count data A
Is counted up by one. The count data A is obtained by calculating the ignition timing θadv delayed by knocking occurrence by the advance amount Δθa.
It is used to determine whether it is time to recover by dv. In step 205, it is determined whether or not the count data A has become equal to the predetermined value 50. Since the flow shown in FIG. 16 is started every 10 msec, the count data A becomes equal to 50 when 0.5 seconds have elapsed since the count data A was initialized. It is recovered every elapse. If the count data A is not equal to 50 in step 205, step 20
Proceed to 6. In step 206, a predetermined advance amount Δθadv is added to the retard value θadv. By this addition, the ignition timing is recovered.

Next, at step 208, the basic ignition timing θba
The ignition timing θign is calculated by adding the ignition timing θadv obtained as described above to se. In step 209, the engine rotation speed N and the intake air amount Q / unit rotation speed Q /
The maximum advance value θres is obtained according to N. Maximum lead angle θ
The res is obtained by reading from the maximum advance value map stored in the ROM 31. In step 210, it is determined whether the ignition timing θign has exceeded the maximum advance value θres. If not, the process proceeds to step 211. If the maximum advance value θres is exceeded, the advance angle is excessive, so that the maximum advance value θres is set to the ignition aging θign in step 211.

Finally, after the ignition timing θign is set,
In step 212, the delay time td, the number of sampling points ns, and the frequency division ratio ts are set to the port 27 according to the engine state.
Output to

The sampling period of the digital value of the output of the vibration sensor is determined by the dividing ratio ts, and the number of sampling points is determined by the number of sampling points ns.

By detecting knocking from a plurality of resonance frequency components and controlling the ignition timing in this way, it is possible to avoid knocking of the engine.

By the way, the output from the vibration sensor attached to the cylinder block has a characteristic that increases as the engine speed and the load increase.

This is due to mechanical noise such as piston sludge in the engine or a change in combustion mode.

In the above description, the knock index is calculated from the knock frequency component and the background level. However, the background level is obtained by averaging the knock frequency components, and has a certain time constant. Therefore, in the transient operation state, it always delays with respect to the new value of the knock frequency component.

This means that the denominator side is apparently smaller in the ratio method of detection for each frequency as the premise of the present invention, and the knock index after calculation is larger.

Since the knock determination is performed by comparing the knock index with the knock determination threshold value, both clearances become very small in a transient state, and as a result, the knock detection means is very sensitive. In the worst case, the relationship between the two is reversed, and the knocking is erroneously determined to determine that knocking has occurred even though knocking has not occurred (FIG. 9 described above).

As described above, there are two kinds of processing methods for smoothing the background level, that is, the processing is performed only in the specific knock control area and the processing is performed irrespective of the area. In the present invention, when the knock control is defined only in a specific region determined by the engine speed and the engine load, the background level smoothing process is limited to the knock control region. This is because the background level is updated to the optimum value when entering the knock area, so that the background level is appropriate and converges from a value higher than the current value, and the background level follows even during transient operation This is because it is possible to improve the controllability and suppress the occurrence of erroneous determination, and to suppress a decrease in the sensitivity of the knock controllability when the vehicle enters the knock control region.

Hereinafter, a detailed example of setting an initial value when entering the knock control area will be described.

As one embodiment, as shown in step 142 of FIG. 1, a background level reference value previously set in the memory is provided as BGLINTi, and when entering the knock control area, this BGBLINTi is used. BGL
i is set as an initial value, and using this initial value, the S / N ratio is calculated in step 104, the knocking determination is performed in steps 105 to 106, and the BGL is determined in step 110.
The averaging process of i is performed.

This BGLINTi may be set for each of the engine speed, load, cylinder, and detection frequency as shown in FIG.

Next, a second embodiment will be described with reference to FIGS.

In step 301 of FIG. 13, it is determined whether the knock control area has left, and if it has left, in step 302, the final value BGLENDi of BGLi in the knock control area is held in the memory. Steps 301 to 302
May be provided before or after step 140 in FIG. Further, BGLENDi is set to the initial value of BGLi in step 150 in FIG. 14 instead of step 142 in FIG. Subsequent processes are the same as those described in the first embodiment.

According to the second embodiment, the number of matching steps for setting BGLINTi described in the first embodiment can be reduced. Further, as shown in FIG. 19, the front BGLENDi may be divided into regions according to the engine speed, load, cylinder, and detection frequency, and may be stored in the memory.

Next, a third embodiment will be described with reference to FIG.

Instead of step 142 in FIG. 1, a detection frequency component (knock frequency component fi) at the time of entering the knock control region is set as an initial value in step 151 in FIG.

According to the third embodiment, it is possible to contribute to saving of memory capacity, and it is effective when a microcomputer system having a small memory capacity is used.

Next, a fourth embodiment will be described with reference to FIG. The fourth embodiment is a combination of the first and second embodiments and is further developed.

Instead of step 142 in FIG. 1, BGLINTi and BGLENDi are compared in step 152 in FIG. 16, and the larger one is set as the initial value of BGLi when entering the knock control area.

Next, a fifth embodiment will be described with reference to FIG. This fifth embodiment is a combination of the first and second embodiments, and is further developed.

Instead of step 142 in FIG. 1, in step 154 in FIG. 17, the BGLINTi is compared with the knock frequency component fi.
Set as the initial value of Li.

According to the fourth and fifth embodiments, the initial value of the background level when entering the knock control area can be set to an appropriate value. If careful, it can be set to a value near or higher than the target value of the background level shown in FIG.

Further, the above-mentioned reference value of the background level may be learned. By learning, the deterioration with time of the engine and the variation in the manufacturing process can be eliminated. This method will be described with reference to FIGS.

At step 140 in FIG. 20, it is determined whether or not the vehicle is within the knock control area. If it is determined that it is within the knock control area, the background level BGLi calculated in step 156 and the background level reference value BGLI
Compare with NTi. If the BGLi is larger, in step 157, instead of the previously held BGLINTi, the BGLi
Hold Li, and the next background level reference value BGLI
NTi. Also, instead of step 157 in FIG.
As shown in step 158 of FIG. 21, BGLINTi held last time and BGLi obtained this time are averaged, that is,

[0096]

(Equation 4)

Alternatively, the reference value BGLINTi of the next background level may be used.

20 and 21 described above may be activated by a routine different from that of FIG. 1, or may be inserted between, for example, steps 140 and 141 in FIG. At that time, step 157 or step 158 and step 141 must be linked.

Further, as shown in FIG.
May be provided with a limit value to prevent learning of an abnormal value. For example, with a preset limit value, the learned BGLI
NTi is compared with the limit value. If the BGLINTi exceeds the limit value, the limit value is held as a background level reference value BGLINTi.

The learning value of BGLINTi is stored in a memory (eg, RAM) different from the memory in which BGLINTi was originally stored.
) May be stored, or the learning value or the limit value may be held or set in an area as shown in FIG.

Further, at the time of the gain correction of the knock sensor output signal and not described, it is better to prohibit the updating of the background learning value during a specific period after the gain switching. The method will be described with reference to FIG.

At step 140 in FIG. 23, it is determined whether or not the region is a knock control region. If it is within the knock control region, it is determined in step 160 whether or not the gain is switched. If it is not at the time of switching, learning of BGLINTi is performed in step 161 and
If there is a change, the learning of BGLINTi is prohibited.

The process in FIG. 23 may be started by a routine different from that in FIG. 1, or may be inserted between Step 140 and Step 141 in FIG.

According to this method, an erroneous learning factor of the learning value of BGLINTi can be eliminated, and learning of an abnormal value can be prevented.

[0105]

According to the present invention, erroneous determination of knocking during transition can be prevented, knock detection accuracy can be improved irrespective of steady or transient engine operation, and optimized ignition timing in all operating conditions Control becomes possible, which can contribute to improvement of engine output, fuel consumption and emission.

[Brief description of the drawings]

FIG. 1 is a flowchart according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a method of calculating knock intensity.

FIG. 3 is a flowchart illustrating a knock determination method.

FIG. 4 is a vibration waveform chart when no knock occurs.

FIG. 5 is a vibration waveform diagram when knock occurs.

FIG. 6 is a diagram relating to the spectrum intensity of knock.

FIG. 7 is a diagram relating to the spectrum intensity of knock.

FIG. 8 is a diagram showing the vibration intensity when knock has occurred and when knock has not occurred.

FIG. 9 is a schematic diagram illustrating a knock erroneous determination during transient.

FIG. 10 is a system configuration diagram.

FIG. 11 is a configuration diagram of a control device.

FIG. 12 is a flowchart showing an ignition calculation.

FIG. 13 is a flowchart for holding BGLi when leaving the knock area.

FIG. 14 is a flowchart showing an example of setting an initial value at the time of entering a knock area.

FIG. 15 is a flowchart showing an example of setting an initial value at the time of entering a knock area.

FIG. 16 is a flowchart showing an example of setting an initial value at the time of entering a knock area.

FIG. 17 is a flowchart showing an example of setting an initial value at the time of entering a knock area.

FIG. 18 is an area-separated memory storage area of BGLINTi.

FIG. 19 is an area storage memory area for BGLENDi.

FIG. 20 is a flowchart illustrating an example of learning of an initial value when a knock region enters.

FIG. 21 is a flowchart illustrating an example of initial value learning at the time of knock region entry.

FIG. 22 is a view showing a limiter of a background level learning value.

FIG. 23 is a flowchart showing the background level learning inhibition at the time of gain switching.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Air cleaner, 2 ... Hot wire type air flow meter, 3 ... Duct, 5 ... Throttle sensor, 6 ... Intake pipe, 7 ... Engine, 8 ... Exhaust pipe, 9 ... Control unit, 11 ... Air-fuel ratio sensor for measuring air-fuel ratio, 12 ... Crank angle sensor, 1
Reference numeral 3 represents an ignition coil, 14 represents a distributor, 15 represents an ignition flag, 16 represents a fuel injection valve, and 200 represents a combustion state sensor.

──────────────────────────────────────────────────の Continued on the front page (72) Inventor, Masami Shida 2520, Oaza Takaba, Katsuta-shi, Ibaraki Co., Ltd. Inside the Automotive Equipment Division of Hitachi, Ltd. Hitachi, Ltd. Automotive Equipment Division (72) Inventor Seiichi Kawasaki 2477 Kashima-Yatsu, Odai-Koba, Katsuta-shi, Ibaraki Prefecture Hitachi Automotive Engineering Co., Ltd. (56) References JP-A-58-45520 (JP) JP-A-3-47449 (JP, A) JP-A-3-124494 (JP, A) JP-A-4-370349 (JP, A) JP-A-6-108915 (JP, A) 4-86531 (JP, A) JP-A-3-14167 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 45/00 368 F02P 5/152 F02P 5/153

Claims (4)

(57) [Claims] 1. A combustion state detecting means provided near a combustion chamber of an internal combustion engine and detecting a combustion state of the internal combustion engine, wherein a characteristic component relating to knocking is extracted from a state signal of the combustion detecting means. An internal combustion engine that calculates a comparison component serving as a reference for knocking determination based on the state signal, and determines knocking based on the characteristic component and the comparison component.
In the knock detection method of Seki, the knock control area
That only performs the operation of said comparison components with a specific operating region, and holds the calculated value of said comparison components in separation of the specific region, wherein at the time of re-entry of a specific operation region, the value of the comparison component the retained, the A comparison value is compared with a reference value of a predetermined comparison component which is a reference value of a comparison component in a specific operation region, and a larger value is set as an initial value of the comparison component at the time of the rush, and the comparison is performed based on the initial value. A method for detecting knocking of an internal combustion engine, comprising calculating a component and determining knocking. 2. The knock detection method for an internal combustion engine according to claim 1, wherein the reference value of the comparison component is:
A knocking detection of an internal combustion engine, wherein the learning is performed only in the specific operation region and the learning is stored in any one of the operation region, the cylinder, the characteristic component, or the region including all of them. Method. 3. The knocking detection method for an internal combustion engine according to claim 2, wherein the learned value of the reference value of the comparison component is larger than the previously stored content by the calculated value of the comparison component obtained this time. when the knocking detection method for an internal combustion engine, characterized in that the calculated value memory is updated. 4. The knocking detection method for an internal combustion engine according to claim 2, wherein
A limit value is provided for the girth value of the comparison component reference value, and when the girth value of the comparison component reference value exceeds the limit value, the limit value is stored and updated instead of the learning value. A method for detecting knocking of an internal combustion engine.