JP2003021032A - Knock control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a knock control device for an internal combustion engine capable of accurately detecting knock generated in the internal combustion engine. SOLUTION: In step S1000, whether or not a knock temporary decision is performed in a statistical processing is decided. If the knock temporary decision using the statistical processing is performed, the step is advanced to step S1100, and whether or not the knock temporary decision using a waveform is performed is decided. If the knock temporary decision using the waveform is performed at this stage, the step is advanced to step S1300. In step S1200, a final knock decision is performed based on results of the two knock temporary decisions, receiving that the two knock temporary decisions are performed. As a result, knock and noise can be accurately detected in the waveform, even in an output signal in which knock and noise are easy to be erroneously detected in the statistical processing, and thereby knock can be accurately detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knock control device for an internal combustion engine, which includes knock determination by statistically processing the output of a knock sensor and knock determination performed based on the output waveform shape of the knock sensor.

[0002]

2. Description of the Related Art Generally, a knock control system is the following technique. First, when an electrical signal from a knock sensor (hereinafter, referred to as a knock sensor output signal) that detects engine vibration exceeds a predetermined level (hereinafter, referred to as a knock determination level), a knock occurs. Is determined to have occurred. If it is determined that knock has occurred from the knock determination result, the ignition timing is retarded to suppress the occurrence of knock, and if it is determined that knock has not occurred, the ignition timing is advanced, Control the ignition timing. At this time, the ignition timing controlled as described above is controlled near the so-called knock limit, so that the fuel consumption and output characteristics of the engine can be maximized.

In such a knock control system, accurate detection of the knock generated in the internal combustion engine plays an important role in accurately controlling the ignition timing near the knock limit. As a technique for detecting this knock, the technique disclosed in Japanese Patent Publication No. 6-60621 is known, and the technique of Japanese Patent Application No. 2000-36462 filed by us is known.

In the technique disclosed in Japanese Examined Patent Publication No. 6-60621, the determination value for determining the knock is corrected by statistically processing the output value from the knock sensor, and the internal combustion engine based on this determination value is corrected. Knock generated during driving is detected.

More specifically, among the output values output from the knock sensor during operation of the internal combustion engine, the maximum value for each combustion cycle of the internal combustion engine is detected, and the detected maximum value V is increased for each cylinder. Individual sampling is performed to obtain the maximum frequency distribution. Then, the population of this maximum value is logarithmically converted. FIG. 5 shows distributions obtained by logarithmically categorizing into two cases, that is, the case where knock occurs and the case where knock does not occur. FIG. 5A shows the distribution when knock does not occur. That is, the fact that (a) in FIG. 5 is represented by one straight line means that this distribution follows one normal distribution. Further, (b) in FIG. 5 shows that the slope changes at a certain inflection point P, and (b) in FIG. 5 shows that the distribution is peculiar to the occurrence of knock, not the normal distribution.

Then, by utilizing this characteristic, it is determined with what percentage of probability the knock occurs, and a determination value for determining the knock is set according to the probability of occurrence of the knock. In the determination of the knock that occurs in the internal combustion engine, it is determined whether or not the knock has occurred based on the determination value thus obtained. That is, in the technique disclosed in Japanese Patent Publication No. 6-60621, the determination value is appropriately set according to the output value of the knock sensor that changes depending on the driving state.

Further, in the technique for detecting knock shown in Japanese Patent Application No. 2000-036462, from the waveform shape obtained from the output signal output from the knock sensor,
The knock is detected when the waveform shape peculiar to the knock is detected.

[0008]

However, in the technique disclosed in the above Japanese Patent Publication No. 6-60621, it is determined that the output signal of the knock sensor exceeds the determination value set by the statistical processing as the knock. Since the judgment is made, it is difficult to set the judgment value. That is, when the determination value is set in the vicinity of the inflection point of the output value, there is a possibility that it may be erroneously determined that the knock has occurred although the knock has not occurred due to the noise being superimposed on the output signal.

Further, in the technique disclosed in Japanese Patent Application No. 2000-036462, in a region where the sensor output is small, a plurality of noises are overlapped with each other so that the waveform of the sensor output signal exhibits a waveform similar to the knock. There is a risk that it may be erroneously determined to have occurred.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a knock control device for an internal combustion engine, which is capable of accurately detecting a knock that occurs in the internal combustion engine.

[0011]

According to the invention of claim 1, a knock sensor for detecting knock of the internal combustion engine, statistical processing means for statistically processing the output signal detected by the knock sensor, and statistical processing. The first provisional determination means for determining the occurrence of knock based on the processing result by the means, and the second provisional determination means for determining the occurrence of knock based on the waveform shape of the output signal detected by the knock sensor. A final knock determination means for finally determining the occurrence of knock based on the results of the temporary knock determination by the first temporary determination means and the temporary knock determination by the second temporary determination means, and the final knock determination means by the final knock determination means. Ignition timing control means for controlling the ignition timing based on the determination result of the occurrence of various knocks.

As a result, in the knock determination using only the knock determination using the statistical processing and the knock determination using the waveform shape of the prior art, the output signal for which the knock is erroneously detected is accurately measured. The occurrence of knock can be determined.

By the way, when the knock determination is performed by the two temporary knock determinations as disclosed in the invention of claim 1, it is expected that the calculation load for the knock determination is increased. Therefore, as in the invention of claim 2, the final knock determination means performs the temporary knock determination by the second temporary determination means when the first temporary knock determination means temporarily determines that the knock has occurred. .

As a result, the second temporary knock determination is executed only when the first temporary knock determination means makes a temporary determination that the knock has occurred. Therefore, it is possible to accurately determine the knock and reduce the calculation load. Is also prevented from becoming large.

Further, as in the third aspect of the invention, the final knock determination means has the knock provisional determination result by the first provisional determination means and the knock or theoretical aerial ratio determination result by the second provisional determination means. When both are tentatively determined to be knocks, it is finally determined that the knocks have occurred.

As a result, even if the first provisional determination means can easily erroneously detect noise as knock, the second provisional determination means can accurately determine knock and noise. Since the first provisional determination means can accurately determine the noise and the knock even if the output signal is likely to be erroneously detected as the knock by the second provisional determination means, the knock is accurately detected. be able to.

Further, in the invention of claim 4, a knock sensor for detecting knock of the internal combustion engine, a statistical processing means for statistically processing an output signal detected by the knock sensor, and a knock processing using the statistical processing means. First to determine the occurrence
No. 1 temporary decision means, frequency analysis means for performing frequency analysis of the output signal detected by the knock sensor, and third temporary decision means for determining the occurrence of knock based on the analysis result of the output signal by the frequency analysis means. , A final knock determination means for finally determining the occurrence of knock based on the determination result based on the first provisional determination means and the determination result based on the third provisional determination means, and a final knock determination means. Ignition timing control means for controlling the ignition timing on the basis of the result of the determination that the knock has occurred.

As a result, in the knock determination using only the knock determination using the statistical processing and the knock determination using the waveform shape of the prior art, it is possible to accurately detect an output signal that has been erroneously detected. The occurrence of knock can be determined.

According to the fifth aspect of the present invention, the final knock determination means temporarily determines that the knocking has occurred when the temporary determination results of both the first temporary determination means and the third temporary determination means are:
Finally, it is determined that a knock has occurred.

As a result, even if the output signal is erroneously detected as noise by the first provisional determination means, it is possible to accurately determine knock and noise by the third provisional determination means. Even if the output signal is apt to be erroneously detected as noise by the third provisional determination means, the first provisional determination means can accurately determine noise and knock, so that the knock is accurately detected. be able to.

Further, according to the invention of claim 6, a knock sensor for detecting knock of the internal combustion engine, and a second provisional determination for determining the occurrence of knock based on the waveform shape of the output signal detected by the knock sensor. Determination means, frequency analysis means for performing frequency analysis of the output signal detected by the knock sensor, and third provisional determination means for determining occurrence of knock based on the analysis result of the output signal by the frequency analysis means,
A final knock determination means for finally determining the occurrence of knock based on the determination result based on the second provisional determination means and the determination result based on the third provisional determination means, and the final knock determination means. Ignition timing control means for controlling the ignition timing based on the determination result of the occurrence of various knocks.

As a result, in the knock determination using only the knock determination using the statistical processing and the knock determination using the waveform shape according to the prior art, the output signal for which the knock is erroneously detected is accurately measured. The occurrence of knock can be determined.

Further, according to the invention of claim 7, the knock sensor for detecting knock of the internal combustion engine, the statistical processing means for statistically processing the output signal detected by the knock sensor, and the statistical processing means are used. First provisional determination means for determining the occurrence of knock, second provisional determination means for determining the occurrence of knock based on the waveform shape of the output signal detected by the knock sensor, and output detected by the knock sensor Frequency analysis means for performing frequency analysis of the signal; third provisional determination means for determining occurrence of knock based on the analysis result of the output signal by the frequency analysis means; determination result based on the first provisional determination; Based on at least any two or more of the determination result based on the second provisional determination means and the determination result based on the third provisional determination means, the occurrence of the knock is finally determined. Provided that the final knock determining means, and ignition timing control means for controlling the final knock determination means final knock determination based on the result of the ignition timing caused by.

As a result, in the determination of knock occurrence using only the knock determination using the statistical processing of the prior art or the knock determination using the waveform shape, the output signal for which the knock is erroneously detected can be accurately measured. The occurrence of knock can be determined.

According to the eighth aspect of the present invention, the final knock determination means has the temporary determination result by the first temporary determination means and the temporary knock determination result by the second temporary determination means and / or the third temporary determination means. When and determine that a knock has occurred, it is finally determined that a knock has occurred.

As a result, even if the output signal is erroneously detected as noise by the first provisional determination means, the second provisional determination means and / or the third provisional determination means can:
Even if the output signal is capable of accurately determining knock and noise, and the third provisional determination means easily erroneously detects noise as knock, the first provisional determination means accurately determines noise and knock. Therefore, the knock can be detected with high accuracy.

According to the invention of claim 9, the first value for detecting the maximum value in the output signal in the predetermined section by the knock sensor is provided.
And a first provisional judgment value setting means for setting a first judgment value based on a distribution shape obtained by logarithmically converting a plurality of maximum values detected by the maximum value detection means. The first provisional determination means provisionally determines occurrence of knock based on the determination value set by the first provisional determination value setting means and the output signal detected by the knock sensor.

As a result, when the maximum value V of the output signal from the knock sensor is in the vicinity of the judgment value set by the statistical processing, this maximum value V is a knock in the temporary judgment using the statistical processing. Even if the determination is made, the maximum value V of the output signal is equal to or larger than the determination value of the tentative determination using the statistical processing, and therefore it is not a signal in a small area as the sensor output area. That is, for example, since it is the area of the sensor output where it is possible to accurately determine whether the signal is a knock signal or a noise signal by tentative knock determination using a waveform shape program, it is difficult to determine whether the signal is knock or noise with only the statistical processing program. It is possible to accurately determine the occurrence of knock even for the output signal.

On the contrary, in the temporary knock determination using the waveform shape, even if the output signal from the knock sensor 6 is small, the temporary knock determination using the statistical processing must not exceed the determination value set by the statistical processing. Since it is not determined that there is a knock, it is easy to make a mistake by only making a knock determination using the waveform shape.Even if the knock signal does not occur even in a small region of the knock signal, it can be erroneously determined as a knock. It can be prevented.

According to the tenth aspect of the present invention, the second maximum value detecting means for detecting the maximum value of the output signal output by the knock sensor and the waveform shape of the output signal output by the knock sensor are the second Determination period setting means for setting a period that is equal to or greater than a predetermined value as a determination period for determining the waveform shape, and the second provisional determination means includes the determination period by the determination period setting means and the maximum value detection means It is advisable to tentatively determine the occurrence of knock based on the maximum value of the output signal detected during the determination period.

According to the eleventh aspect of the present invention, the A / D converting means for A / D converting the output signal output from the knock sensor at every predetermined time and accumulating in time series, and the predetermined for the A / D converting means. A third provisional determination is provided, which includes frequency analysis means for repeatedly performing frequency analysis each time the A-D converted value of the point is accumulated, and addition means for adding frequency analysis performed by the frequency analysis means a plurality of times. The means separates knock and noise from the result of the adding means and tentatively determines the occurrence of knock.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> This embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of the present invention. In FIG.
1 is a 4-cylinder 4-cycle engine, 2 is an air cleaner, 3
Is an air flow meter that detects the intake air amount of the engine and outputs a signal according to the detected intake air amount. Reference numeral 4 is a throttle valve. Reference numeral 5 is a reference for detecting a reference crank angle position (for example, top dead center) of the engine. Corner sensor 5A
And a crank angle sensor 5B for generating an output signal at every constant crank angle of the engine. Reference numeral 6 denotes a knock sensor for detecting the vibration of the engine block corresponding to the knock phenomenon of the engine by a piezoelectric element type (piezo element type), an electromagnetic type (magnet, coil) or the like. Reference numeral 9 is a water temperature sensor that generates a signal according to the cooling water temperature of the engine, 12 is a fully closed switch (idle switch) for outputting a signal when the throttle valve 4 is in a fully closed state, and 13 is a fully opened throttle valve 4. A full-open switch (power switch) for outputting a signal when the state is in the state, 14 is an air-fuel ratio of the exhaust gas (A /
This is an O2 sensor that generates an output signal depending on whether F) is richer or leaner than the stoichiometric air-fuel ratio.

Reference numeral 8 denotes an engine control unit (hereinafter, referred to as an engine control unit) for controlling the ignition timing and the air-fuel ratio of the engine in accordance with the input / output signal states from the respective sensors and switches.
Referred to as an ECU) 10 is an igniter and an ignition coil that receive an ignition timing control signal output from the ECU 8 to cut off the power supply to the ignition coil. The high voltage generated in the ignition coil is applied to the ignition plug of a predetermined cylinder at an appropriate time through the power distribution unit of the distributor 5. Reference numeral 11 is an injector for injecting fuel into the intake manifold based on the fuel injection time (τ) determined by the ECU 8.

Next, the detailed configuration and operation of the ECU 8 are shown in FIG.
Follow the instructions below. In FIG. 2, 6 is an engine 1.
Is a knock sensor as a vibration pickup attached to the cylinder block of the engine 1 for detecting a vibration waveform signal generated in the engine 1 and converting it into an electric signal. The knock sensor 6 is for detecting a vibration waveform signal in a wide frequency band. A non-resonant sensor is used. A signal from the knock sensor 6 and a low pass filter (Low) for removing frequency components of 20 KHz or more for preventing aliasing noise.
Pass Filter: low frequency band pass filter;
Hereinafter, the gain switch is provided via a LPF 21 and a high pass filter (high frequency band pass filter; hereinafter referred to as HPF) 22 for removing frequency components of 1 KHz or less unrelated to the knock signal. 23 is input.

The gain switch 23 has a wide dynamic range equivalent to that of a 16-bit A / D converter for adjusting the input signal to an appropriate size. The signal from the gain switch 23 is a digital signal processor (Digital Signal Process) capable of high-speed multiplication processing.
r; hereinafter referred to as DSP) 30. This D
SP30 is an A / D (analog-digital) converter 3
1 and parallel I / O (hereinafter referred to as PiO) 32,
33 is provided to perform gain selection by a gain switching signal for the gain switching device 23 and communication with a microcomputer 40 described later.

The # 1 cylinder discrimination signal is input from the microcomputer 40 to the DSP 30 as a reference signal of the crankshaft (not shown) of the engine, and the knock determination signal from the DSP 30, which determines whether or not a knock has occurred, is described below. It is input to the computer 40. Note that #
The cylinders other than the one cylinder are calculated using a counter. In addition, in the microcomputer 40, among the various sensor signals from the crank angle sensor (not shown), the air flow meter 3, the water temperature sensor 9, etc. of the engine 1, digital signals are unchanged and analog signals are A / D converter 41.
Are converted into digital signals via and input. Based on these input signals, the microcomputer 40 calculates the ignition timing, the fuel injection amount, etc., and the correction according to the knock determination signal is executed.

Here, the microcomputer 40 is a CP as a central processing unit for executing various well-known arithmetic processing.
U, a ROM storing a control program, a RAM storing various data, a B / U (backup) RAM, an input / output circuit, and a logical operation circuit including a bus line connecting them.

The knock detection method of this embodiment, which is performed in such a configuration, will be described in detail below with reference to the drawings.
First, the flowchart of FIG. 13 is a main routine for finally determining a knock. In this final determination, the final knock determination is performed based on the temporary knock determination using statistical processing described later and the temporary knock determination that performs the knock determination based on the waveform shape of the knock.

First, in step S1000, it is determined whether or not a temporary knock determination is made in the statistical processing. Then, if it has not been performed, this routine is finished as it is. On the other hand, if the temporary knock determination using the statistical processing is performed, the process proceeds to step S1100, and it is determined whether the temporary knock determination using the waveform shape is performed. here,
If the provisional determination has not been made, this routine is finished as it is. On the other hand, if the temporary knock determination using the waveform shape is performed, the process proceeds to step S1300.

In step S1200, in response to the two preliminary knock determinations to be described later, a final knock determination is made based on the results of the two temporary knock determinations. As a final knock determination method, the temporary knock determination result in the statistical processing and the temporary knock determination result using the waveform shape are knocked in the internal combustion engine only when both are determined to be knocks. It is determined that Then, based on this final knock determination result, step S130
At 0, the ignition timing calculation is performed. The calculation of this ignition timing is shown in the flowchart of FIG.

First, in step S1301 of FIG.
The basic ignition timing is calculated from the engine speed Ne and the load of the internal combustion engine, for example, the intake air amount by using a map or the like. Then, in step S1302, a delay amount calculation is performed. The calculation of the retard amount is performed based on the final knock determination result performed in step S1200 of FIG. That is, the retard amount is calculated only when it is determined that the final knock determination result is that the knock has occurred. The calculation of the retard angle amount may be a conventionally known method, for example, a method of calculating a predetermined retard angle amount according to the driving state by a map. When the retard amount is calculated,
Next, in step S1303, the final ignition timing is calculated. When a knock is generated by the final knock determination result, the ignition timing is set to an ignition timing that reflects the result of the knock determination, and when it is determined that no knock is generated, the ignition retard by the knock is set. The ignition timing is set.

Next, each knock provisional determination, that is, the provisional determination using the statistical processing and the provisional determination using the waveform shape will be described in detail. First, a temporary determination program using statistical processing will be described.

[Statistical Processing Program] First, the principle of temporary knock determination using statistical processing will be described. This program is roughly divided into the following two parts. The first is the presentation of a basic algorithm for correcting the knock determination level to an appropriate value based on the information of the knock signal. In other words, the basic value of logarithmically converting the maximum value of each cycle of the knock sensor, determining the suitability of the current knock determination level from the distribution shape obtained by sampling a large number of this, and correcting the knock determination level in the desired direction To provide a general algorithm.

The second is to provide a practical method and apparatus for utilizing this basic algorithm and realizing it in a simpler and lower cost manner. That is, based on the conclusions drawn from the basic algorithm,
The sensor signal does not necessarily have to be logarithmically transformed, and this algorithm can be replaced by multiplication and division, thus further simplifying the process. Moreover, the second item includes a method of knowing the multicycle distribution shape of the sensor signal without using a large number of RAM capacities (temporary storage locations of data).

First, the technical basis of the present invention will be described. Generally, a frequency distribution obtained by sampling a large number (peak value) V of maximum values (peak values) V of a knock sensor output signal during engine combustion in a steady operation state for each cylinder is as shown in FIG. FIG. 4 is a rewriting of this distribution into a cumulative distribution with the upper probability as the vertical axis.

By rewriting this cumulative distribution as shown in FIG. 4, the unique property of the distribution of the maximum value V will be described below.

In FIG. 5, the vertical axis represents the value Log (V) obtained by logarithmically converting the maximum value V of the knock sensor output signal. The horizontal axis of the figure shows the upper% points (points at which the upper probability is the% value) of the cumulative distribution corresponding to the ratio u of the deviation and the standard deviation in the normal distribution according to the normal distribution table.

That is, the horizontal axis u is defined by the following equation.

Here, x = Log (V) μ = Log (V50) (that is, the average value of Log (V)) σ = σ (x) (that is, the standard deviation of Log (V)) This definition equation (1) 5 corresponds to FIG. 5, the slope of the straight line in FIG. 5 corresponds to σ, and the value of Log (V) at u = 0 (V50 is a point where the upper probability is 50%) corresponds to μ.
To rewrite the cumulative distribution as shown in FIG. 3 according to the coordinates in FIG. 4, if the data at the (upper) 5% point is V5, u = 1.6 is obtained from the normal distribution table, and (1.6, Lo
% (g (Vs)) is the task of plotting points
Just do about the points.

5 (a) and 5 (b) show the distribution of Log (V) when the knock is not generated at all and when the knock is generated at a certain frequency. (A)
The fact that is represented by one straight line means that this distribution follows one normal distribution. Further, in (b), the slope changes at a certain inflection point P, and it can be seen that this distribution is composed of two different normal distributions.

Further, in (b), the slope of the straight line on the left side of the inflection point P is almost the same as that of (a), and the slope of the straight line on the right side is about twice as large as the slope of (a). The inflection point P shifts to the left side of the figure as the frequency of knock occurrence increases. From these, the inflection point P of (a) and (b)
It is considered that the distribution on the left side is a distribution peculiar to normal combustion in which knock has not occurred, and the distribution on the right side of the inflection point P in (b) is a distribution peculiar to knocking.

Regarding these two inclinations, the latter is 2 more than the former.
Since it is about twice as large, it is thought that the distribution becomes a normal distribution with the latter slope in the state where ignition knocks occur, but it is not possible to misidentify that distribution as the distribution when no knocks occur. Absent.

For the above reason, it is possible to determine the knock occurrence state from the distribution of the value Log (V) obtained by logarithmically converting the maximum value V of the knock sensor output signal. In this way, it is possible to judge the knock occurrence state from Log (V), but it is necessary to use an expensive device such as a logarithmic converter or to grasp the distribution of Log (V). Since it requires a long time and a large number of RAMs, it is necessary to further devise it.

Therefore, the following method is used as a simple method for correcting the knock determination level by utilizing the characteristics of the Log (V) distribution shape described above. First, the distribution when no knock has occurred is as shown in FIG.
It becomes like (a). Here, for example, the 10% point of the distribution,
The values at the 50% point and 90% point are V10, V50, and V, respectively.
If it is 90, Log (V10) -Log (V50) =
The relational expression Log (V50) -Log (V90) is established. This equation can be transformed as follows:

V10 / V50 = V50 / V90 (2) Further, when knocking occurs, when the frequency is low, it becomes as shown in FIG. 6B, and the expression (2) is established. However, the distribution when the knock occurs frequently is shown in Fig. 6 (c).
And V10 / V50> V50 / V90 (3). That is, in other words, V10, V50, V9
If the relationship of 0 is as in the expression (2), it can be determined that the knock occurrence frequency is too low, and conversely, if it is as in the expression (3), it can be determined that the knock occurrence frequency is too high.

Next, a simple method for obtaining V10, V50 and V90 will be described. For example, the maximum value V incorporated this time
On the other hand, if V> V10, ΔV10 is set as the set value V
10 = V10 + 9 × ΔV10, V <10 if V <V10
= V10-1 × ΔV10 By increasing the ratio of the change amount of V10 to 9 times, V10 is the upper 10% of the distribution.
The value matches the point. That is, if V10
Is the value of the upper 10% point, the probability of V> V10 is 0.1, and the probability of V <V10 is 0.9. The expected value of the quantity is 9 × 0.1-1 × 0.9 = 0, which stabilizes at the current value. If V10 is smaller than the value of the upper 10% point, for example, the value of the upper 20% point, V> V1
The probability of 0 is 0.2, and the probability of V <V10 is 0.
8, the expected value of the change amount of V10 is 1.8-0.
8 = 1, V10 changes to increase, and the top 1
Settle down to the 0% point. Similarly, when V10 is larger than the value of the upper 10% point, the expected value of the amount of change in V10 becomes negative, and the expected value changes to decrease and settles to the value of the upper 10% point.

Regarding V50, the ratio of the amount of change in the case of V> V50 and the amount of change in the case of V <V50 may be set to one,
V90 may be 1/9 times. By using this method, the value of any% point of the distribution can be easily obtained. In addition, it is better that each variation amount is a value according to the knock sensor output, rather than a constant value. For example V5
0 may be obtained as follows. ΔV50 is V and V5
The average of the differences of 0 is set and ΔV50 = (3 × ΔV50 +
| V-V50 |) / 4, and if V> V50, then V50
= V50 + ΔV50 / 4, if V <V50, V50 = V
50-ΔV50 / 4.

V10 and V5 thus obtained
0, V90, for example, V1 every 128 cycles
An accurate knock determination level can be created by calculating the values of 0 / V50 and V50 / V90, determining the knock occurrence state based on the magnitude relationship, and correcting the knock determination level. In addition, V when the frequency of knocking is low
The ratio of 10 to V50 does not change much even if the engine condition or the engine model changes, so the ratio of V10 to V50 has a certain value (for example, V10 when knocking does not occur).
It is also effective to correct the knock determination level so that it becomes a value slightly larger than the ratio of V50 to V50).

The following method is also effective for correcting the knock determination level by utilizing the characteristics of the distribution shape of Log (V). In this method, for example, the median value V50 of the distribution of the maximum value V is obtained, a certain constant is set to K0, and V is V
This is a method utilizing the fact that the probability of> K0 × V50 and the probability of V <V50 / K0 differ between when knock occurs and when knock does not occur.

The distributions of LOG (V) when no knock occurs and when the knock frequency is small are as shown in FIGS. 7 (a) and 7 (b), respectively. In such a state, Log within the range of V50 / K0 <V <K0 × V50
Since the linearity of the distribution of (V) is maintained, V> K0 × V
The probability of 50 and the probability of V <V50 / K0 are equal. In the example of the figure, both are 2%.

On the contrary, Lo when the knock occurs frequently
The distribution of g (V) is as shown in (c) of the figure, and V> K0 ×
The probability of V50 is greater than the probability of V <V50 / K0. In the example of the figure, they are 16% and 2%, respectively. That is, the knocking occurrence state can be determined by the probability of V> K0 × V50 and the probability of V <V50 / K0. In addition, V> K when there is no knock
The frequency of 0 × V50 does not change much depending on the engine condition and engine model. Therefore, knock this frequency so that it has a predetermined value (a value slightly larger than the frequency of V> K0 × V50 when no knock occurs). A method of correcting the judgment level is also effective.

In the method described above, the knock determination level may be created as K × V50, for example, by performing four arithmetic operations on the value of the% point in the V distribution.

The purpose, basis and basic principle of the tentative knock determination by the statistical processing have been described above. Next, a program for realizing the knock determination method by the statistical processing will be described.

The temporary knocking determination and the correction of the knocking determination level will be described with reference to the flowchart of FIG. 8 as an example. First, when the engine is started and an interrupt for ignition timing calculation is made, the interrupt is started. First, step S1
At 00, the above-described maximum value V in the predetermined section of the knock sensor output signal is read for each cylinder, and step S30
Go to 0. In step S300, the percentage points of the distribution of the maximum value V are calculated. The processing content of step S300 will be described later in detail.

Next, at step S400, it is judged from the engine load or the like whether or not the engine is in the knock control state, and if NO, this routine is terminated. If YES is determined in step S400, the process proceeds to step S500, and the knock determination level Vref for each cylinder is set to Vref =
It is calculated from the arithmetic expression K × V50. If the maximum value V> Vref in step S600, it is provisionally determined that knock has occurred, and the knock flag is set to "H". And
The process proceeds to step S900, the knock determination level is corrected, and this routine ends. The processing content of step S900 will be described later in detail.

The overall flow of knock determination and knock determination level correction for carrying out the present invention has been described above. Next, referring to the flow charts of FIGS. 9 and 10, the distribution of the output value V from the knock sensor will be described. Step S300 for calculating the percentage point and Step S9 for correcting the knock determination level
00 will be described.

The flowchart shown in FIG. 9 is a method of correcting the knock determination level from the relationship of the ratios of the values of the three% points of the V distribution, that is, the 10% point, the 50% point and the 90% point. 8 is a subroutine of step S300. Similarly, FIG. 10 is a subroutine of step S900 of FIG.

First, in the flowchart of FIG. 9, V10 for obtaining the maximum value V of the output signal from the knock sensor read this time at step S301 and the value at the 10% point of the distribution of the output signal V (RAM for each cylinder is stored in RAM). Stored)), and if YES, the process proceeds to step S302, and V10 = V10 + as described above.
9 × V10, and in the case of NO, the process proceeds to step S303 and V10 = V10−ΔV10. By doing so, V10 settles at the value of the top 10% point of the distribution. Next, the process proceeds to step S304, V> V50 is determined, and if YES, the process proceeds to step S305, V50 = V50 + ΔV
50, and if NO, proceed to step S306 and set V5
0 = V50−ΔV50.

By doing so, V50 settles at the median value of the distribution. Next, the process proceeds to step S307 and V> V90
If YES, the process proceeds to step S308,
V90 = V90 + ΔV90. If NO, the process proceeds to step S309 to set V90 = V90-9 × ΔV90. By doing so, V90 settles at the upper 90% point of the distribution. The value of the% point of the distribution is obtained by such steps.

Next, step S in the flowchart of FIG.
The flowchart of FIG. 10 will be described as a subroutine of processing 900. First, in step S901, it is determined whether or not the engine is in a steady operation state based on changes in the engine rotation speed Ne and the engine load Q / Ne. If NO is determined here, step S906
Go to. When YES is determined in step S901, the process proceeds to step S902, and the counter N that counts the combustion cycle of each cylinder is counted as N = N + 1. In step S903, it is determined whether or not the steady state as the operating state has continued for a predetermined number of cycles No. If YES is determined here,
Proceed to step S904, and V10 / V50> V50 / V
The judgment of 90 is made. On the other hand, if NO is determined, the process returns to the flowchart of FIG. 8 and ends the routine.

If YES is determined in the step S904, the process proceeds to a step S905, and the knock determination level is set to Vref = Vref-ΔV with respect to the set value ΔV, and if NO is determined, the process proceeds to step X-15 and Vref. =
Let Vref + A × ΔV. Here, A is set to a value larger than 1.

As described above, the reason why the amount A × ΔV for correcting the knock determination level Vref in the direction of increasing it is larger than the amount ΔV for correcting the knock determination level Vref is to increase when the frequency of knocking is low. This is because the probability of being performed is equal to the probability of being determined to be NO, and in such a case, the knock determination level is corrected to increase. In this way, the knock determination level is corrected, the process proceeds to step S906, the count value N is set to 0, and the present routine ends.

As described above in detail, in the temporary knock determination program using the statistical processing, the knock determination value for determining the knock is set by the statistical processing, and the output value exceeding the knock determination value is detected. Is temporarily determined to be a knock. That is, since the output value that is determined to be a knock is always an output value that is equal to or greater than the determination value, it is not possible to temporarily determine that an output signal obtained in a region where the output signal is small is a knock.

[Waveform Shape Program] Next, a program for making a temporary knock determination based on the waveform shape will be described in detail below.

First, the characteristics of each of the three signal shapes obtained by integration / differentiation by the DSP 30 with respect to the vibration waveform signal from the knock sensor 6 will be described with reference to the time chart of FIG. Here, FIG. 11A is a knock signal Sknock, FIG. 11B is a mechanical noise signal SFnoise, and FIG. 11C is an electrical noise signal SEn.
Indicates oise.

Knock signal Sknoc shown in FIG. 11 (a)
k is generated by self-ignition of the fuel in the combustion chamber of the engine 1. Therefore, the knock signal Sknock has a characteristic that a large output appears at the initial stage of the signal and then gradually attenuates due to pressure resonance in the combustion chamber. That is, in the knock signal Snock, a large peak value SP appears at an earlier peak generation time SPT with respect to a relatively long generation period SD that exceeds the predetermined signal presence / absence determination level Sth. Note that the length of the signal generation period SD is not determined by the signal presence / absence determination level Sth, but the signal shape may be known, and therefore the learning precision of the signal presence / absence determination level Sth may not be so good.

The mechanical noise signal SFnoise shown in FIG. 11 (b) is the friction between the individual parts of the engine 1,
That is, it is generated by friction noise. That is,
In the rotating body, the frictional pressure gradually increases and gradually decreases, so that the mechanical noise signal SFnoise has a characteristic that the transition also occurs. That is, in the mechanical noise signal SFnoise due to friction, a small peak value SP appears in the peak generation time SPT near the center of the generation period SD with respect to the generation period SD exceeding the predetermined signal presence / absence determination level.

Further, the electric noise signal SEnoise shown in FIG. 11 (c) is instantaneously generated by turning on / off the electric load. Therefore, the electric noise signal SEnoise has a characteristic that the gradient is steep at the rising and falling edges of the signal. That is, the electrical noise signal S
In Enoise, a large peak value SP appears in a short peak generation time SPT for a short generation period SD that exceeds a predetermined signal presence / absence determination level Sth. The mechanical noise signal SSnoise due to the tapping sound is the electrical noise signal SE.
It has a signal shape similar to noise.

As described above, the knock signal and the noise signal respectively exhibit the waveform shapes of the above characteristics. Hereinafter, a waveform shape program executed by the DSP 30 and utilizing the above-described waveform shape characteristic will be described in detail with reference to the flowchart of FIG. The temporary determination routine for knocking is repeatedly executed by the DSP 30 for each combustion cycle of the engine 1 based on the reference position signal and the # 1 cylinder determination signal from the microcomputer 30.

In FIG. 12, in step S1001, the ratio (SP / SD) between the peak value SP and the generation period SD in the signal shape obtained for the vibration waveform signal from the knock sensor 6 is preset for knock determination. It is determined whether the predetermined value K1 (lower limit value) and the predetermined value K2d (upper limit value) are within the range. That is, step S1001
In the determination process (1), which of the three waveform shapes shown in FIG. 11 the vibration waveform signal from knock sensor 6 has is determined. The determination condition of step S1001 is satisfied, that is, K1 <(SP / SD) <K2.
When the inequality is satisfied, the peak value SP with respect to the occurrence period SD has the knock signal Sknock shown in FIG.
Since it has a peculiar relationship to step S1002, the process proceeds to step S1002. Then, in step S1002, the knock temporary determination flag for the waveform shape program is set to "1" because the knock has occurred, and the present routine ends.

On the other hand, when the determination condition of step S1001 is not satisfied, that is, the inequality of K1 <(SP / SD) <K2 is not satisfied, the process proceeds to step S1003. In step S1003, it is determined that no knock has occurred, and the above-described temporary determination flag is set to "0", and this routine ends. Here, the inequality (SP / SD) ≦ K1 is satisfied when the peak value SP is small and the generation period SD is long, and the electric noise signal SEnoise shown in FIG.
It can be seen that it is e or a mechanical noise signal SSnoise due to a tapping sound.

As described above, in the present embodiment, when it is determined that knock has occurred in each temporary determination using the temporary knock determination by the statistical processing program and the temporary knock determination by the waveform shape program. Only, it is determined that the knock has finally occurred. By making the determination in this way, it is possible to accurately determine the occurrence of knock even with respect to the output signal for which the knock was erroneously detected in the knock determination using only the statistical processing program or the waveform shape program.

That is, when the maximum value V of the output signal from the knock sensor 6 is near the determination value set by the statistical processing, this maximum value V is determined to be a knock by the temporary determination of the statistical processing program. However, since the maximum value V of this output signal is equal to or larger than the determination value of the statistical processing program, it is not a signal in a small area as the sensor output area. That is, since it is the area of the sensor output where it is possible to accurately determine whether it is a knock signal or a noise signal by provisionally determining the knock by the waveform shape program, it is difficult to determine whether the signal is the knock or the noise with only the statistical processing program. Also, it is possible to accurately determine the occurrence of knock.

On the contrary, in the temporary knock determination by the waveform shape program, even if the output signal from the knock sensor 6 is small, the temporary knock determination by the statistical processing program does not exceed the determination value set by the statistical processing. Since it is not determined that there is a knock, it is possible to prevent a erroneous determination that a knock occurs even if the knock signal does not occur even in a small region of the knock signal that is easily erroneously determined by the waveform shape program.

In the present embodiment, both the tentative judgment of the statistical processing program and the waveform shape program are made at the same time. You may judge. Similarly, the knock determination may be performed by activating the statistical processing program only when the waveform shape program determines that the knock has occurred.

As described above, in the present embodiment, when the maximum value V of the output signal from the knock sensor is near the judgment value set by the statistical processing, this maximum value V uses the statistical processing. Even if it is determined that it is a knock by tentative determination,
Since the maximum value V of this output signal is equal to or higher than the determination value of the temporary determination using the statistical processing, it is not a signal in a small area as the sensor output area. That is, for example, since it is the area of the sensor output where it is possible to accurately determine whether the signal is a knock signal or a noise signal by tentative knock determination using a waveform shape program, it is difficult to determine whether the signal is knock or noise with only the statistical processing program. It is possible to accurately determine the occurrence of knock even for the output signal.

On the contrary, in the temporary knock determination using the waveform shape, even if the output signal from the knock sensor 6 is small, the temporary knock determination using the statistical processing must not exceed the determination value set by the statistical processing. Since it is not determined that there is a knock, it is easy to make a mistake by only making a knock determination using the waveform shape.Even if the knock signal does not occur even in a small region of the knock signal, it can be erroneously determined as a knock. It can be prevented.

In the present embodiment, the statistical processing means is shown in the flowchart of FIG. 9, the first provisional determination means is shown in the statistical processing program, the final knock determination means is shown in the flowchart of FIG. 13, and the ignition timing control means is shown in FIG. Each corresponds to a flowchart and functions.

<Second Embodiment> In the first embodiment, the occurrence of knock is determined from the temporary determination of the statistical processing program and the temporary determination of the waveform shape program. In the present embodiment, the knock occurrence is determined based on the tentative determination of the statistical processing program and the tentative determination of a frequency analysis program (hereinafter, referred to as FFT program) described later. The knock determination of the present embodiment will be described below using the main routine of FIG.

First, in step S1000, it is determined whether a tentative knock determination has been made by the statistical processing program. Since the statistical processing program has been described in detail in the first embodiment, the description thereof will be omitted. If it is determined that the temporary knock determination is not performed, step S
The routine proceeds to 1300, the ignition timing calculation processing is executed, and this routine is ended. On the other hand, if it is determined in step S1000 that the temporary knock determination is being performed by the statistical processing program, the process proceeds to step S2002.

In step S2002, the FFT described later is performed.
It is determined whether or not the temporary knock determination by the program is performed. If the knock preliminary determination by the FFT program has not been performed, this routine is ended via step S1300. On the other hand, if the knock preliminary determination is made by the FFT program, step S2003.
Go to and make the final knock decision. As the final knock determination, the knock is generated as the final determination only when the temporary determination by the statistical processing program and the temporary determination by the FFT program are determined to be knocks.
Then, in step S1300, this result is reflected in the ignition timing control, and this routine is ended.

Next, the temporary knock determination by the above FFT program will be described with reference to the drawings.

[FFT Program] First, FFT
The knock phenomenon will be described in order to explain the physical reason for making knock determination using (frequency analysis by fast Fourier transform). Knock is a phenomenon in which unburned gas in a cylinder is compressed by the combustion gas, self-ignites, and rapidly burns to resonate in the cylinder. If this knock is controlled at a minute level, fuel efficiency can be improved without damaging the engine. JP-A-3-47
As disclosed in the embodiment of No. 449, the above-mentioned resonance has a natural frequency determined by the bore diameter of the engine and the sound velocity, and the resonance vibration mode when the cylinder radial direction is n and the circumferential order is m. Let Pnm be, for example, in FIG.
It is predicted that a knock component will appear at a frequency as shown in (b).

However, when the knocking frequency is analyzed in an actual engine, the knocking component does not always occur at the frequency shown in FIG. 15 (b). Figure 15
(A) shows a frequency analysis result of a signal from a knock sensor attached to an engine block (not shown) for one ignition and when no knock is generated. ρ10
The vibration modes corresponding to ρ20 and ρ20 match the values expected from FIG. 15B, but ρ01 and ρ30 are 1 respectively.
Knock components are generated at 15.5 KHz and 16.5 KHz although they are expected to be 4.6 KHz and 16.0 KHz. Since the ρ10 and ρ20 modes similarly vary in another ignition cycle, it is necessary to search for the knock generation frequency for each ignition.

Next, a knock determination method will be described. The following findings were obtained from the engine combustion experiment. That is, in the vibration sensor attached to the block, the output of each knock generation frequency is different for each knock generation. For this reason, it is desirable to determine a knock detection threshold value for each knock generation frequency and make knock determination.

Next, the operation of the DSP 30 in the configuration of FIG. 2 of the first embodiment will be described with reference to the timing chart of FIG. A of FIG. 16 shows a reference position signal, and the trailing edge of the signal is ATDC-10 ° CA of each cylinder, whereby the reference position interrupt processing is executed in the period a from time t1 in FIG. B of FIG. 16 shows a knock determination section, and b and c of FIG. 16 show a period of a timer 1 interrupt process of FIG. 17 which will be described later, which is executed from the times t2 and t3. 17d shows the period of the timer 2 interrupt processing of FIG. 18 which will be described later and is executed from time t2.
16e shows the processing period such as FFT executed in the main routine.

First, the reference position interrupt processing a is executed at the fall of the reference position signal at time t1 in FIG. 16, and the start time of the knock determination section is set in the timer 1 as indicated by f. As a result, the timer 1 interrupt process b is executed at the judgment section start time of time t2. As a result, the end time of the knock determination section is reset in the timer 2 as indicated by g, and the timer 2 interrupt process d
Is executed to start AD conversion of the knock signal. This processing is performed once every 20 μsec using the timer 2 interrupt.

The FFT can handle only a predetermined number of data of 2 ^{n in} principle. Therefore, the FFT is performed here in units of 2 ⁷ = 128. The A-D converted values are accumulated in time series, and when the number reaches 128, F in FIG.
In the FT1 section, the knock signal data AD-converted in the section AD1 is FFTed. At the same time A-D conversion is section AD
2, following AD3. The number of A / D converted data in each section AD1 and AD2 is 1 for the division of each section AD1, AD2 and AD3.
The number of divisions is 28, and the A / D conversion operations are performed in the knock determination section in the same and continuously, and each A / D conversion data is accumulated in time series. Similarly in section AD2, when the number of data reaches 128, section F
Perform the second FFT with FT2. The second FFT result is added to the first result.

When the knock determination section ends, after the FFT ends in the main routine, the knock generation frequency is searched for each ignition based on the addition result of each FFT in one knock determination section to determine the knock intensity. Then, the result is sent to the microcomputer 40. It should be noted that the knock determination section does not usually end at the same time as the 128-point A-D conversion ends, and normally the A-D conversion is terminated midway like the section AD3 in FIG. In this case, the remaining A-D
The conversion point portion executes 128-point FFT assuming that the AD conversion input is 0.

If the knock detection section ends before the previous FFT has ended, the next FFT is executed after waiting for the end of the previous FFT. As mentioned above, multiple times of FF
With the configuration in which the result of T is added, the knock determination section can be set freely. In addition, at low rotation speed, the frequency can be analyzed with a smaller calculation amount than the frequency analysis of the entire FFT once.

17 to 25 are flowcharts showing the flow of the program of the DSP 30. Next, at time t1 in FIG. 16, the reference position interruption program shown in step S2040 of FIG. 18 is started by the angle interruption at the reference position. Here, the reference position indicates the crank angle of the engine, which is 10 ° CA before the top dead center (BTDC) of each cylinder, and is sent from the CPU in the microcomputer 40.
First, in step S2050, cylinder discrimination is performed, and a value corresponding to the distance from the cylinder to be ignited this time to the knock sensor is output. This signal is also a signal sent from the CPU in the microcomputer 40, which is 1 only for the # 1 cylinder, and the other cylinders are calculated using the counter. Step S
Reference numeral 2060 denotes a rotation speed calculation part, which calculates based on the time required from the previous reference signal to the current reference signal. In step S2070, input gain setting, fail determination and timer setting are performed as preprocessing. In step S2080, timer 1 is set in order to wait for the crank angle set in advance according to the engine speed. Here, the normal knock occurs at about 15 ° C after the top dead center (ATDC).
A to ATDC 70 ° CA, so step S208
At 0, the time corresponding to the value of ATDC 10 ° CA, which is slightly before, is set.

When the time set in step S2080 (t2 in FIG. 16) comes, step S20 in FIG.
The timer 1 interrupt program shown at 90 is started.
First, in step S2091, the knock determination end flag, which will be described later, is 1, so it is determined that the knock determination interval has started, and the process advances to step S2092 to set the knock determination interval end flag to 0. Next, proceeding to step S2093, the timer 1 is reset to the time corresponding to a value of about ATDC 70 ° CA, and then proceeding to step S2094, A-
The timer 2 for starting the D conversion is set and activated. After that, the process advances to step S2095 to activate the main routine.

Further, the reset time of the timer 1 (see FIG. 16)
At time t3), the timer 1 interrupt program shown in step S2090 of FIG. 17 is started again. This time, in step S2091, since the knock determination end flag is 0, it is determined that it is the knock determination end interval, the process proceeds to step S2096, the knock determination interval end flag is set to 1, and then the process proceeds to step S2097 and the timer 2 starts. The operation is stopped to end the A-D conversion.

Next, the timer 2 interruption step S2097 shown in FIG. 19 will be described. This timer 2 interrupt is executed every 20 μsec. First, step S20
After 99, the A / D converter 41 starts the A / D conversion of the knock signal, the process proceeds to step S100, and the A / D converted value by the A / D converter 31 is loaded into the DSP 30, and then step S2101. Go to and take this AD
The converted value is stored and accumulated in a RAM (not shown) in the DSP 30 in time series.

FIG. 20 shows the pre-processing of step S2070 of FIG. 19. First, in step S2071, the gain of the gain switch 23 is adjusted so that the input signal has an appropriate size. Next, in step S2072, it is determined whether the knock sensor 6 has failed. As the fail determination method, as shown in FIG. 21, step S272
1 is the value of PALL detailed in FIG.
The 16-annealed value is compared with the predetermined value, and if the 1 / 16-annealed value is smaller than the predetermined value, step S2722.
Proceed to and output the sensor fail output to the microcomputer 4.
Supply to 0 CPU.

FIG. 23 shows the main routine started in step S2094 of FIG. 17. First, in step S2102, it is determined whether the knock temporary determination section end flag using FFT is 1, and the knock temporary determination section end flag is 1. If not, the process proceeds to step S2103, it is determined whether the 128-point A-D conversion is completed, and if it is not completed, the process returns to step S2102, and if it is completed, the process proceeds to step S2104 to execute the FFT, and
The result is added to the previous addition result.

Next, when the knock determination section end flag is 1 in step S2102, the flow advances to step S2105 to set the value of the portion less than 128 in the A / D conversion at that time to a predetermined value = 0, and then in step S2106. Go to F
The FT is executed and the result is added to the addition result up to the previous time.

Then, in the next step S2107, after the post-processing such as the search of the knock generation frequency for each ignition based on the addition result of each FFT in the knock determination section, the ignition is performed once in step S2108. The knock strength is determined for each.

FIG. 24 shows step S2107 of FIG. 23 in more detail. The frequency-spectral intensity characteristic corresponding to FIG. 15 (a) obtained based on the addition result of each FFT in one knock determination section is shown in FIG. From step S3
101 to S3105, each knocking frequency ρ10, ρ
By executing each peak value search and each output calculation in the 20, ρ01, ρ30, ρ11 modes, each knock occurrence frequency is searched for each ignition, and the output corresponding to each knock occurrence frequency is calculated. In the next step S3106, the total power of the knock signals is calculated.

Referring to FIG. 25, step S3101 of FIG.
Will be described in more detail. Note that step S31 in FIG.
02 to S3105 are basically the same as those in FIG. Figure 1
The simplified result of addition of each FFT corresponding to the main part of the characteristic of 5 (a) is shown in FIG. 26, and the peak value search (knock occurrence frequency search) and its output calculation method will be described on behalf of this characteristic. To do. First, in step S2131, the lower limit frequency fL in the ρ10 mode is read from a ROM (not shown), and in the next step S2132, the upper limit frequency fu in the ρ10 mode is similarly read. Here, the upper and lower limit frequencies fL and fu are the resonance vibration mode (knock occurrence frequency) ρ
It is a value that is set in advance with a certain allowance for the value expected as 10.

In the next step S2133, the upper and lower limit frequencies f
After obtaining the maximum value fMAX of the spectral intensities in L and fu, in step M134, the total sum P10 of the spectral intensities at fMAX ± 1172 Hz is obtained. Next, in step S1135, a value MD10 obtained by normalizing the sum P10 of spectral intensities is obtained. That is, the sum MD10 of the spectral intensities is divided by a value obtained by multiplying the distance from the corresponding cylinder to the knock sensor 6 by the total number of data to obtain a normalized value MD10.

According to FIG. 22, step S3106 of FIG. 24.
Will be described in more detail. From the frequency-spectrum intensity characteristic corresponding to FIG. 15A obtained based on the addition result of each FFT in one knock determination section in step S2141, the sum PAL of all spectrum intensities of 5 to 20 KHz.
Find L.

FIG. 27 shows the knock determination step S2 of FIG.
108 in more detail. First, step S21.
After prohibiting the interrupt at 51, the intermediate layer output NMOUTn is calculated by the following equation at step S2152.

NMOUTn = CYL × WCYLHn + T
RPM x WRPMHn + PALL x WALLHn + MD
10 x W10Hn + MD20 x W20Hn + MD01 x
W01Hn + MD30 x W30Hn + MD11 x W11
Hn + WOFFHn Here, CYL is called the difference between cylinders, and is the reciprocal of what is obtained by subjecting the sum PALL of all spectrum intensities of each cylinder to 3/4, and TRPM is the microcomputer 40.
It is a value indicating the cycle of the reference position signal input from the CPU inside. PALL is the total value of the vibration energy of the knock sensor 6 between 5 KHz and 20 KHz, and MD
10, MD20, MD01, MD30, MD11 are summation values in the vicinity of the natural vibrations of the pressure wave caused by knocking inside the respective cylinders, and the difference between the cylinders,
And is normalized by dividing by the number of data input at the time of vibration analysis. WCYLHn, WRPMHn, WALL
Hn, W10Hn, W20Hn, W01Hn, W30H
n, W11Hn, and W0FFHn are weighting coefficients called synapse coupling coefficients. (Here, n is the number of intermediate neurons, and in the example, 16 of 0 to 9 and A to F)
It takes one value and is initially initialized to 0.

NMOUTn is the result obtained by Equation 1, and the upper 8 bits of this 16-bit data are the sigmoid function f (χ) = 1 / (1 + exp (-χ)) as shown in FIG. 28 in the next step S2153. ), The table is looked up by the function table of FIG.

In the next step S2154, it is determined whether or not the number of intermediate neurons is n = 16. When the number n of intermediate neurons is not reached, the process returns to step S2152, and when it becomes equal to the number n of intermediate neurons, the process proceeds to step S2155.

In step S2155, the weighting factors WH0 to WHF as shown in the following equations are applied to the n = 16 hidden layer outputs H0 to HF thus obtained, and the same calculation as in the hidden layer is performed. The output NN of the output layer neuron
Get OUT.

NNOUT = H0 × WH0 + H1 × WH1
+ H2 x WH2 + H3 x WH3 + H4 x WH4 + H5 x
WH5 + H6 x WH6 + H7 x WH7 + H8 x WH8 +
H9 x WH9 + HA x WHA + HB x WHB + HC x W
HC + HD × WHD + HE × WHE + HF × WHF This output NNOUT is shown in FIG. 28 in the next step S2156.
A 16-bit output corresponding to the knock strength is obtained by performing a table lookup with a function table as shown in FIG. 3, and in the next step M157, a process of outputting the upper 2 bits is performed to obtain a determination result KNK according to the knock strength.

Here, each of the above-mentioned weighting factors is obtained by learning by a generally known method such as the backpropagation method, and the output KNK for an unknown input group is obtained based on the learning data given by this. I will get it. Then, in the next step M158, the interrupt is permitted.

Incidentally, in the above-mentioned embodiment, FIG.
Although the knock strength determination is performed using the neural net in the knock determination step S2108, the knock strength determination may be performed using fuzzy inference.

In this embodiment, the frequency analysis means is shown in the flow chart of FIG. 27, and the third tentative determination means is shown in FIG.
The final knock determination means functions in the flowchart of FIG. 14 and corresponds to step S2003 of the flowchart of FIG.

(Other Example 1) In the first embodiment, provisional knock determination using a statistical processing program and temporary knock determination using a waveform shape program are provided.
A final knock determination was performed based on the two temporary knock determinations. Further, in the second embodiment, provisional knock determination using a statistical processing program and provisional knock determination using a frequency analysis program are provided, and the final knock determination is performed based on these two preliminary knock determinations. did.

In this embodiment, provisional knock determination using a frequency program and temporary knock determination using a waveform shape program are provided, and the final knock determination is performed based on these two temporary knock determinations. . This will be described below with reference to the flowchart of FIG. First, step S20
At 02, it is determined whether or not the temporary knock determination using the FFT program is performed. Here, if the temporary knock determination is not made, the normal ignition timing setting process is performed in step S1300 and the present routine is ended.

On the other hand, if the temporary knock determination using the FFT program has been made, the process advances to step S1100 to determine whether the temporary knock determination using the waveform shape program has been performed. If the temporary knock determination is not made, this routine is ended via step S1300. If it is determined in step S1100 that temporary knocking determination using the waveform shape program is performed, the process proceeds to step S4000. In step S4000, the FFT
When both the temporary knock determination result using the program and the temporary knock determination result using the waveform shape program are knocks, it is finally determined that the knock has occurred. Then, in step S1300, if the knock has occurred, the ignition timing is retarded. On the other hand, when the knock has not occurred, the normal ignition timing is set and the present routine is ended.

In the present embodiment, the final knock determination is performed from the temporary knock determination result using the FFT program and the temporary knock determination result using the waveform shape program. However, the knock determination using the FFT program is performed. Only when it is determined that the temporary determination result is knock, the temporary knock determination using the waveform shape program may be performed.

In the present embodiment, the final knock determination means corresponds to step S4000 in the flowchart of FIG. 30 and functions.

(Other Embodiment 2) This embodiment is provided with knock temporary judgment using a statistical processing program, knock temporary judgment using an FFT program, and knock temporary judgment using a waveform shape program. The final knock determination is performed based on the temporary determination result. Below, FIG.
This will be described using the flowchart of No. 1.

First, in step S1000, it is determined whether or not temporary knock determination using a statistical processing program has been performed. If the temporary knock determination is not made, this routine is ended via step S1300. On the other hand, if the temporary knock determination using the statistical processing program is performed in step S1000, the process proceeds to step S2002, and it is determined whether the temporary knock determination using the FFT program is performed. Here, if the temporary knock determination is not made, the present routine is ended via step S1300. When it is determined in step S2002 that the knock preliminary determination using the FFT program is performed, the process proceeds to step S1100, and it is determined whether the knock temporary determination using the waveform shape program is performed.
If the temporary knock determination is not made, step S130.
This routine is ended via 0. On the other hand, if it is determined that the temporary knock determination is made, step S5000.
Go to.

In step S5000, the final knock determination is made based on the temporary knock determination using the statistical processing program, the knock temporary determination using the FFT program, and the knock temporary determination using the waveform shape program. Make a knock decision. In the final knock determination, it may be determined that the knock has finally occurred only when all of the three knock temporary determination results indicate that the knock has occurred.

Further, when it is determined that the two provisional determinations out of the three are knocks, it may be determined that the knocks finally occur. At this time, it is preferable that at least the knock temporary determination result by the statistical processing program is determined to be a knock. The reason for this is that when the maximum value V of the output signal from the knock sensor is near the determination value set by the statistical processing, this maximum value V is determined to be a knock by the temporary determination using the statistical processing. However, since the maximum value V of this output signal is equal to or higher than the determination value of the temporary determination using the statistical processing, it is not a signal in a small area as the sensor output area. That is, for example, since it is a sensor output area in which it is possible to accurately determine whether the signal is a knock signal or a noise signal by tentative knock determination using a waveform shape program or an FFT program, it is possible to determine whether the signal is a knock or a noise with only the statistical processing program. It is possible to accurately determine the occurrence of knock even for an output signal that is difficult to generate.

Conversely, the waveform shape program or FF
In the temporary knock determination using the T program, even if the output signal from the knock sensor 6 is small, the temporary knock determination using the statistical processing determines that the knock is generated unless the determination value set by the statistical processing is exceeded. Therefore, it is possible to prevent the erroneous determination of the knock even if the knock signal does not occur even in a small region of the knock signal, which is apt to be erroneously determined only by the knock determination using the waveform shape.

In the present embodiment, the final knock determination is performed only when all three provisional determinations are made. For example, the knock provisional determination result using the statistical processing program causes knock. FF only when it is determined that
The knock provisional determination using the T program may be performed. Furthermore, when it is determined that knock has occurred as a result of temporary knock determination using the FFT program, temporary knock determination using the waveform shape program may be performed.

In this embodiment, the final knock determination means corresponds to step S5000 in the flowchart of FIG. 31 and functions.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an ECU of the present invention.

FIG. 3 is a frequency distribution chart of the maximum output value from the knock sensor.

FIG. 4 is a cumulative frequency distribution chart of the maximum output value from the knock sensor.

FIG. 5: Ratio u and Lo of deviation and standard deviation in normal distribution
It is a figure which shows the relationship of g (V).

FIG. 6 is a diagram illustrating the principle of temporary knock determination by a statistical processing program.

FIG. 7 is a diagram illustrating the principle of temporary knock determination by a statistical processing program.

FIG. 8 is a diagram showing setting of a temporary knock determination and a knock determination value by a statistical processing program.

9 is a subroutine of a distribution percentage point calculation process in step S300 of FIG.

FIG. 10 is a subroutine of a knock determination level correction process in step S900 of FIG.

FIG. 11 is an explanatory diagram showing respective characteristics of each signal obtained by processing the vibration waveform signal input to the DSP.

FIG. 12 is a flowchart of knock temporary determination by a waveform shape program.

FIG. 13 is a main flowchart of knock determination in the first embodiment.

FIG. 14 is a main flowchart of knock determination in the second embodiment.

15A is a frequency-spectral intensity characteristic diagram of a knock sensor signal, and FIG. 15B is an engine knock generation frequency analysis diagram.

FIG. 16 is a timing chart of the frequency analysis program according to the second embodiment.

FIG. 17 is a flowchart of timer 1 interruption in the frequency analysis program according to the second embodiment.

FIG. 18 is a flow chart of reference position interruption in the frequency analysis program of the second embodiment.

FIG. 19 is a flowchart of timer 2 interrupt in the frequency analysis program according to the second embodiment.

FIG. 20 is a flowchart of preprocessing in the frequency analysis program according to the second embodiment.

FIG. 21 is a flow chart of sensor failure determination in the frequency analysis program of the second embodiment.

FIG. 22 is a flowchart of power sum calculation in the frequency analysis program according to the second embodiment.

FIG. 23 is a flowchart of a main routine in the frequency analysis program of the second embodiment.

FIG. 24 is a flowchart of post-processing in the frequency analysis program according to the second embodiment.

FIG. 25 is a flowchart of ρ10 mode peak value search in the frequency analysis program according to the second embodiment.

FIG. 26 is a characteristic diagram for explaining the operation of a peak value search in the frequency analysis program according to the second embodiment.

FIG. 27 is a flowchart of temporary knock determination in the frequency analysis program according to the second embodiment.

FIG. 28 is a function table search characteristic diagram in the frequency analysis program of the second embodiment.

FIG. 29 is a flowchart showing an ignition timing calculation process according to the first embodiment.

FIG. 30 is a flowchart of knock determination according to another embodiment.

FIG. 31 is a flowchart of knock determination according to the second embodiment.

[Explanation of symbols]

1 ... engine, 2 ... Air cleaner, 3 ... Air flow meter, 4 ... Throttle valve, 5 ... Distributor, 6 ... knock sensor, 8 ... ECU, 11 ... Injector.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 45/00 F02D 45/00 368D G01L 23/22 F02P 5/153 G01M 15/00 A 17/12 F02P 5 / 15 D G01L 23/22 17/00 R G01M 15/00 F term (reference) 2F055 AA23 BB14 CC14 DD20 EE23 FF49 GG31 2G087 AA26 BB12 FF22 3G019 AB01 CC15 GA05 GA08 GA09 GA06 FA07 GA09 GA06 FA06 GA09 FA06 FA10 FA05 GA10 FA10 FA05 GA06 FA06 GA06 FA06 FA06 GA09 FA06 FA06 GA06 FA06 GA08 FA09 GA06 FA06 GA02 GA06 FA06 GA02 FA06 GA08 FA09 GA06 FA06 GA08 FA09 GA06 FA06 GA08 FA09 GA06 FA06 GA08 FA09 GA13 3G084 BA17 CA05 DA04 DA20 DA24 DA38 EA01 EA02 EA04 EA11 EB08 EB25 EC04 FA07 FA10 FA18 FA20 FA25 FA26 FA29 FA33 FA39

Claims (11)

[Claims] 1. A knock sensor for detecting knock of an internal combustion engine, statistical processing means for statistically processing an output signal detected by the knock sensor, and occurrence of knock based on a processing result by the statistical processing means. The first provisional determination means for determining, and the second provisional determination means for determining the occurrence of knock based on the waveform shape of the output signal detected by the knock sensor, the knock by the first provisional determination means A final knock determination means for finally determining the occurrence of knock based on the result of the temporary determination and the temporary knock determination by the second temporary determination means; and a final knock occurrence determination result by the final knock determination means. A knock control device for an internal combustion engine, comprising: an ignition timing control means for controlling an ignition timing based on the ignition timing control means. 2. The final knock determination means performs the temporary knock determination by the second temporary determination means when the first temporary determination means temporarily determines that a knock has occurred. The knock control device for an internal combustion engine according to claim 1. 3. The final knock determination means determines that a knock has finally occurred when both the first temporary determination means and the second temporary determination means determine that a knock has occurred. The knock control device for an internal combustion engine according to claim 1, wherein the knock control device is an internal combustion engine knock control device. 4. A knock sensor for detecting knock of an internal combustion engine, statistical processing means for statistically processing an output signal detected by the knock sensor, and determining occurrence of knock using the statistical processing means. 1
Tentative determination means, frequency analysis means for performing frequency analysis of the output signal detected by the knock sensor, and third tentative determination means for determining the occurrence of knock based on the analysis result of the output signal by the frequency analysis means. The determination result based on the first provisional determination means, and the third
The final knock determination means for finally determining the occurrence of knock based on the determination result based on the provisional determination means, and the ignition timing is controlled based on the final determination result for knock generation by the final knock determination means. A knock control device for an internal combustion engine, comprising: ignition timing control means. 5. The final knock determination means determines that a knock has finally occurred when both the first provisional determination means and the third provisional determination means have provisionally determined that a knock has occurred. The knock control device for an internal combustion engine according to claim 4, wherein: 6. A knock sensor for detecting knock of an internal combustion engine, second provisional determination means for determining occurrence of knock based on a waveform shape of an output signal detected by the knock sensor, and the knock sensor. Frequency analysis means for performing frequency analysis of the output signal detected by the: third provisional determination means for determining the occurrence of knock based on the analysis result of the output signal by the frequency analysis means; and the second provisional determination means. The determination result based on the
The final knock determination means for finally determining the occurrence of knock based on the determination result based on the provisional determination means, and the ignition timing is controlled based on the final determination result for knock generation by the final knock determination means. A knock control device for an internal combustion engine, comprising: ignition timing control means. 7. A knock sensor for detecting knock of an internal combustion engine, statistical processing means for statistically processing an output signal detected by the knock sensor, and determining occurrence of knock using the statistical processing means. 1
And a second provisional determination means for determining the occurrence of knock based on the waveform shape of the output signal detected by the knock sensor, and a frequency for performing frequency analysis of the output signal detected by the knock sensor. Analysis means, a third provisional determination means for determining the occurrence of knock based on the analysis result of the output signal by the frequency analysis means, a determination result based on the first provisional determination, and the second provisional determination Final knock determination means for finally determining the occurrence of knock based on at least any two or more determination results of the determination result based on the means and the determination result based on the third provisional determination means, A knock control device for an internal combustion engine, comprising: ignition timing control means for controlling ignition timing based on a final knock occurrence determination result by the final knock determination means. . 8. The final knock determination means knocks a temporary determination result by the first temporary determination means and a temporary knock determination result by the second temporary determination means and / or the third temporary determination means. 8. When it is determined that the knock has occurred, it is finally determined that the knock has occurred.
A knock control device for an internal combustion engine according to item 1. 9. A first maximum value detecting means for detecting a maximum value in an output signal of a predetermined section by the knock sensor; and a logarithmic conversion of a plurality of maximum values detected by the maximum value detecting means. And a first provisional determination value setting means for setting a first determination value based on the distribution shape of the distribution pattern, wherein the first provisional determination means is a determination value set by the first provisional determination value setting means. 8. The occurrence of knock is tentatively determined based on and an output signal detected by the knock sensor.
Alternatively, the knock control device for the internal combustion engine according to claim 8. 10. A second maximum value detecting means for detecting a maximum value of an output signal output by the knock sensor, and a period during which the output signal output by the knock sensor is equal to or more than a second predetermined value. A determination period setting unit that determines the waveform shape as a determination period, and the second provisional determination unit detects the determination period by the determination period setting unit and the maximum value detection unit during the determination period. 4. The provisional determination of knock occurrence is made based on the maximum value of the output signal that
Alternatively, the knock control device for the internal combustion engine according to any one of claims 6 to 8. 11. An A / D conversion unit for A / D converting an output signal output from the knock sensor at predetermined time intervals and accumulating in time series, and an A-D conversion unit at a predetermined point in the A / D conversion unit. A frequency analysis unit that repeatedly performs a frequency analysis each time a conversion value is accumulated, and an addition unit that adds the frequency analysis performed a plurality of times by the frequency analysis unit, and the third provisional determination unit, The knock control device for an internal combustion engine according to any one of claims 4 to 8, wherein knock and noise are separated from the result of the adding means to temporarily determine the occurrence of knock.