JPH0663482B2 - Knocking control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a knocking control device for an internal combustion engine, which corrects a knocking determination level and effectively detects knocking.

[Prior Art] The mechanical vibration generated in the engine due to abnormal combustion of the internal combustion engine is detected as an electrical signal, and knocking occurs when the amplitude of the electrical signal exceeds a predetermined determination level (knock determination level). There is a known technique for determining.

Since the detection of this knocking is performed based on a subtle knock signal that changes depending on the driving state, the setting of the knock determination level is extremely important, and various techniques for setting a more favorable knock determination level than before have been proposed. ing. For example, (1) using the maximum value (peak) of the amplitude value of the electric signal in a predetermined crank angle range (knock detection period) after ignition of at least one predetermined cylinder, and using the maximum value in a plurality of ignition cycles. "Knocking detection method for internal combustion engine" for detecting occurrence of knocking by calculating average value and comparing magnitude of knock determination level based on the average value and amplitude value of electric signal in knock detection period 58-28645).

Further, in the method (1), the knock determination level may not be appropriately set depending on the driving state, and thus the following technique has been developed in recent years. That is, (2) as shown in FIG. 13, the maximum value of the amplitude value of the knock signal in the knock detection period is obtained a predetermined number of times, the most frequent point A is obtained from the distribution of the occurrence frequencies thereof, and the coefficient k is assigned to the maximum frequency point. "Knocking control device for engine" in which the knocking determination level Axk is calculated by multiplying the above, and the knocking control level is set using this knocking determination level Axk.
63-253155).

(3) As shown in FIG. 13, from the distribution of the frequency of occurrence of the maximum value of the knock signal, a frequency average value B which is an average value of the frequency of occurrence is obtained, and the frequency average value B is multiplied by a coefficient K to knock. The determination level B × K is calculated, and this knock determination level B ×
"Knocking detection device for internal combustion engine" that uses K to detect knocking (Japanese Patent Application No. 63-115133).

[Problems to be Solved by the Invention] However, the conventional techniques have the following problems and have not been satisfactory yet. That is, (1) In a configuration in which knocking occurrence is detected by comparing the average value of the amplitude values of the electric signal in a plurality of ignition cycles with the detected amplitude value of the electric signal, the value of the large amplitude value of the electric signal is detected. Is added, the average value when knocking occurs tends to shift to a side larger than the average value when knocking does not occur. Therefore, there is a problem that the knock determination level is cumulatively increased due to the increase of the average value, and it becomes impossible to determine the occurrence of knocking unless an electric signal having a larger amplitude value is input, and the knocking detection accuracy deteriorates.

(2) Further, in the configuration in which the knock determination level A × k is calculated based on the maximum frequency point A of the maximum value of the amplitude value of the knock signal, and knocking is detected using this knock determination level A × k, Compared with the example using the average value, the knock determination level A × k does not change significantly, and therefore, there is an advantage that the accuracy does not decrease when knocks occur frequently. However, in the case of using the most frequent point A, since it is necessary to detect a knock signal and perform statistical processing over a predetermined period, the number of data to be stored is large and the RAM becomes a heavy burden.
There is also a problem that it takes a long time to calculate.

(3) Furthermore, in the configuration in which the frequency average value B of the maximum values of the knock signal amplitude values is obtained and the knock determination level B × k is set based on the frequency average value B, the average value of (1) above is used. The fluctuation of the knock determination level B × k was smaller than that of the conventional one, but the knock determination level B × k also increased as the occurrence of knocking increased. Particularly, when knocking occurs frequently, as shown in FIG. 13 (iii), the knocking determination level A × k based on the most frequent point A in (2) above becomes larger, and it becomes difficult to detect knocking. There was an occasion.

It is an object of the present invention to provide a knocking control device for an internal combustion engine that finds the most frequent points with a simple structure and realizes accurate knocking detection based on the most frequent points.

Structure of the Invention [Means for Solving the Problems] The present invention, which has been made to achieve the above object, detects a mechanical vibration of an engine body of an internal combustion engine M1 and knocks a knock signal, as illustrated in FIG. A knock signal detecting means M2 for outputting, a most frequent point calculating means M3 for obtaining the most frequent point of the maximum value in the knock detection period of the knock signal outputted by the knock signal detecting means M2, and the most frequent point calculating means M3. Knock determination means M4 for determining the knock determination level based on the determined most frequent points and determining the occurrence of knock using the knock determination level
In a knocking control device for an internal combustion engine, comprising: If the maximum value of the knock signal detected by the knock signal detecting means M2 is in a predetermined range exceeding the maximum frequency point, the maximum frequency point is predetermined. If the maximum frequency of the knock signal detected by the most frequent point addition updating means M5 for adding and updating the value and the knock signal detecting means M2 is within a predetermined range below the most frequent point, the maximum frequency The gist is a knocking control device for an internal combustion engine, characterized in that it includes a most frequent point subtraction updating means M6 for subtracting and updating a predetermined value from points.

[Operation] As illustrated in FIG. 1, the knocking control device for an internal combustion engine of the present invention detects mechanical vibrations of the engine body of the internal combustion engine M1 by the knock signal detecting means M2 and outputs a knock signal. Obtain the most frequent point of the maximum value in the knock detection period of the knock signal by the frequency point calculating means M3, further, by the knock determination means M4, obtain the knock determination level based on the most frequent point of the maximum value of the knock signal, this knock Knocking occurrence is determined using the determination level. Then, when the maximum value of the knock signal is in the predetermined range exceeding the most frequent points, the most frequent point addition updating means M5 adds the predetermined value to the most frequent points to update. On the other hand, when the maximum value of the knock signal is within the predetermined range below the most frequent point, the most frequent point subtraction update means M6 updates the maximum frequency point by subtracting the predetermined value from the maximum frequency point.

That is, the above-described configuration quickly finds a suitable most frequent point by increasing or decreasing the most frequent point according to the maximum value of the knock signal detected during the knock detection period.

Next, the principle of the present invention will be described in detail with reference to FIG.

Here, consider a case where the distribution of the maximum values of the knock signals detected over a plurality of knock detection periods is, for example, statistically the graph shown in FIG. In the figure, is the most frequent point of the maximum value of the knock signal obtained up to the previous time.
A1, A2, A3, and the shaded areas a that spread to the left and right of them,
The areas of b, a ′, b ′, b ″, b ″ are the most frequent points A1 ~
The area | region which updates A3 is shown. In addition, areas a, a ',
B "is a region for decreasing correction, and regions B, B ', B" are regions for increasing correction.

Here, for example, when the most frequent frequency point A1 of the previous time is, and when it is determined in the next measurement that the maximum value of the knock signal is in the area i, the most frequent frequency point A1 is decreased and corrected so as to move to the left side of the graph. On the other hand, when it is determined that the maximum value of the knock signal is in the area mouth, the most frequent point A1 is increased and corrected so that moves to the right side of the graph.

That is, since the maximum value of the knock signal statistically has a high probability of appearing in the vicinity of the maximum frequency point A of this graph, the maximum value of the measured knock signal is often closer to the area mouth than the area a. When the updating process is repeated, the most frequent point A1 comes close to the most frequent point A in the graph. This also applies to the other most frequent points A2 and A3, and each time the update is repeated, the most frequent point A of the graph is approached.

The probability that the maximum value of the knock signal occurs is the frequency average value B
Since it is the same on both sides of, the calculated most frequent points A1 to A3 are the most frequent points A of the graph unless the area to be updated is limited.
To the frequency average value B without converging on. Therefore, the update areas of a predetermined width are set on both sides of the most frequent point A.

In this way, the maximum value of the knock signal and the most frequent points A1 to A3
By comparing and, and updating the most frequent points A1 to A3 one after another based on the latest knock signal, it is possible to quickly obtain the desired most frequent points A1 to A3 close to the most frequent point A in the graph. . Therefore, the coefficient k is assigned to the most frequent points A1 to A3.
It is possible to obtain the knock determination level by multiplying by and to accurately grasp the knocking based on the knock determination level.

The technical problems of the present invention are solved by the action of each component of the present invention as described above.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail with reference to the drawings. FIG. 3 shows the system configuration of the engine knocking control device according to the first embodiment of the present invention.

As shown in the figure, the engine knocking control device 1
Is composed of a four-cylinder engine 2 and an electronic control unit (hereinafter simply referred to as ECU) 3 for controlling the engine 2.

The engine 2 has a first cylinder (# 1) 11 and a second cylinder (# 2)
12th, 3rd cylinder (# 3) 13 and 4th cylinder (# 4) 14
Spark plugs 15, 16, 17, and 18 are provided in the cylinders 11, 12, 13, and 14, respectively. These spark plugs 15, 16, 17, 18 have a high voltage required for ignition generated by an igniter 19 equipped with an ignition coil, through a distributor 20 equipped with a cam shaft that works in conjunction with a crank shaft (not shown),
Distributed and supplied.

The engine knocking control device 1 is a resonance type knock sensor that is provided as a detector in a cylinder block of the engine 2 and outputs mechanical vibration as an electrical knock signal.
31. A cylinder discrimination sensor 32 which is built in the distributor 20 and generates a cylinder discrimination signal (G signal) at every 1/4 rotation of the cam shaft of the distributor 20, that is, every crank angle 180 [°], and the cam of the distributor 20. Every 24th revolution of the shaft, that is, crank angle 30
A rotation angle sensor 33 that also functions as a rotation speed sensor that generates a rotation angle signal (Ne signal) every [°], an intake pipe pressure sensor 34 that measures the intake pipe pressure inside the intake manifold, and an engine 2
A water temperature sensor 35 for measuring the engine temperature from the cooling water temperature is provided. The detection signal of each of these sensors is input to ECU3,
The ECU 3 controls the engine 2.

ECU3 is MPU3a, ROM3b, RAM3c, backup RAM3d, timer
It is configured as a logical operation circuit centered on 3e, and the common bus 3f
It is connected to the input / output units 3g and 3h via the to input / output with the outside.

The knock signal output from the knock sensor 31 has an impedance conversion function, and has a frequency band (7-
Bandpass filter circuit 3 whose pass band is 8 [KHz] 3
i, bandpass filter circuit 3i according to the control signal of MPU3a
The peak hold circuit 3j that performs the hold operation of the maximum amplitude of the knock signal that has passed through the output signal of the peak hold circuit 3j is A / D-converted according to the control signal of the MPU 3a, and A / D
A / D converter 3 that outputs D conversion end interrupt signal to MPU3a
k is input to the MPU 3a via the input / output port 3g. The cylinder discrimination signal (G signal) detected by the cylinder discrimination sensor 32 is stored in the buffer 3m and the interrupt request signal forming circuit 3n, and the rotation angle signal (Ne signal) detected by the rotation angle sensor 33 is stored in the buffer 3p.
Interrupt request signal forming circuit 3n and speed signal forming circuit 3q
An interrupt signal and a rotation speed signal are input to the MPU 3a from the input / output port 3h via each. Further, the detection signal of the intake pipe pressure sensor 34 is input to the buffer 3r, the detection signal of the water temperature sensor 35 is input to the buffer 3s, and is input via the multiplexer 3t and the A / D converter 3u which operate according to the control signal of the MPU 3a. Input from output port 3h to MPU3a. Meanwhile, MPU
3a outputs a control signal to the drive circuit 3v via the input / output port 3g to drive the igniter 19 to control the ignition timing.

Next, the knocking detection start time calculation processing executed by the ECU 3 is shown in FIG. 4, the knocking detection end time calculation processing is shown in FIG. 5, the A / D conversion start processing is shown in FIG. 6, and the knocking detection processing is shown in FIG. Will be explained based on each.

First, the knocking detection start time calculation process will be described based on the flowchart shown in FIG. This knocking detection start time calculation processing is executed in accordance with an interrupt signal generated for each predetermined specific crank angle {top dead center (TDC) in this embodiment}.

First, in step 100, a process of reading various data is performed. In the following step 110, a process of calculating the knocking detection start time t1 is performed. Here, the knocking detection start time t1 is the starting crank angle of a predetermined knocking detection period (in this embodiment, for example, ATDC10
~ 20 [° CA]}, detected current crank angle Cθ
[° CA], and is calculated based on the current time value TM of the timer 3e. Next, the routine proceeds to step 120, where the knocking detection start time t1 calculated at step 110 is set in a register inside the MPU 3a, and then this processing is once terminated.
After that, this process is performed in steps 100 to 1 for each specific crank angle.
Repeat 20.

Next, the knocking detection end time calculation process will be described based on the flowchart shown in FIG. This knocking detection end time calculation processing is executed in accordance with the interrupt signal generated at time t1 calculated in the above knocking detection start time calculation processing.

First, in step 200, a process of outputting a high level ("1") control signal to the peak hold circuit 3j is performed.
By the processing of this step 200, the peak hold circuit 3j
Starts the peak hold operation of the knock signal. In the following step 210, a process of reading various data is performed. Next, the routine proceeds to step 220, where processing for calculating the knocking detection end time t2 is performed. Here, the knocking detection end time t2 is the crank angle from the start time to the end time of the predetermined knocking detection period (in this embodiment, for example, 60 to 90 [° CA]), the detected current crank It is calculated based on the angle Cθ [° CA] and the current measured value TM of the timer 3e. Continue to step 230, step 2
After performing the process of setting the knocking detection end time t2 calculated in 20 in the register inside the MPU 3a, this process is once ended. After that, this process repeats steps 200 to 230 each time an interrupt signal is generated.

Next, the A / D conversion start processing will be described based on the flowchart of FIG. This A / D conversion start processing is executed in accordance with the interrupt signal generated at time t2 calculated by the knocking detection end time calculation processing described above.

First, in step 300, a process of outputting a high level ("1") control signal to the A / D conversion circuit 3k is performed. Through the processing of step 300, the A / D conversion circuit 3k starts A / D conversion of the knock signal. After performing the processing of this step 300, this processing is once terminated. After that, this process
Step 300 is repeated every time an interrupt signal is generated.

Next, the most frequent point updating process used for knocking detection will be described with reference to the flowchart of FIG. In this most frequent point update process, knocking detection process (step
400 to 440) and the update process (steps 445 to 470) of the most frequent points, which is the main part of the present embodiment, will be described subsequently. Note that this processing is performed by the A / D conversion end interrupt signal output from the A / D converter 3k (in this embodiment, for example, A / D conversion end signal).
It is activated when 10 [msec] has passed after the start of D conversion}.

First, in step 400, a process of reading various data is performed. In the following step 405, the A / D converted value A /
A process of setting D to the knock sensor output signal amplitude value (knock signal amplitude value) a is performed. Next, in step 410, a process of outputting a peak hold end control signal to the peak hold circuit 3j is performed. That is, MPU3a is
A low-level ("0") control signal is output to the peak hold circuit 3j.

In the following step 415, it is determined whether or not the knock signal amplitude value a is equal to or lower than the knock determination level k × A for determining the occurrence of knocking, that is, whether knocking has occurred, and it is determined that the knocking has not occurred. Proceed to step 420, while
If it is determined that it has occurred, the process proceeds to step 425. here,
The value k is a coefficient (for example, k = 2 in this embodiment),
The value A is the maximum frequency point of the knock signal amplitude value a and is updated successively.

In step 420, it is determined whether or not the count value of the counter n that counts the number of consecutive knock-free states is 10 or more. If an affirmative determination is made, the processing proceeds to step 430, while if a negative determination is made, a step 435 is performed. Proceed to.

In step 435, which is executed when the knocking-free state is less than 10 consecutive ignition cycles, a process of adding 1 to the count value of the counter n is performed, and then the process proceeds to step 445.

On the other hand, in step 430, which is executed when the knocking-free state is 10 consecutive ignition cycles or more, the ignition timing advance correction value θ is advanced by the crank angle Y. This advance angle correction value θ is a value used in a known ignition timing calculation process executed for each predetermined crank angle.
That is, in the ignition timing calculation process, the ROM 3 is set in advance based on the intake pipe pressure PM and the rotation speed Ne of the engine 2.
The basic ignition timing θ0 is calculated according to the map stored in b, and the basic ignition timing θ0 is corrected by the advance correction value θ to calculate the target ignition timing θ ^* . Therefore, step 43
By the processing of 0, the target ignition timing θ ^* is advanced by the crank angle Y.

In the following step 440, the process of resetting the counter n to the value 0 is performed, and then the process proceeds to step 445.

In step 425, which is executed when knocking occurs, the ignition timing advance correction value θ is retarded by the crank angle X. By this processing, the target ignition timing θ ^* is retarded by the crank angle X, and the occurrence of knocking is suppressed. Then, the process proceeds to step 445 via step 440.

In the following step 445, it is determined whether or not the knock signal amplitude value a is less than or equal to the product of the most frequent point A and the coefficient k1, and if a positive determination is made, the routine proceeds to step 450. Here, the coefficient k1 (for example, k1 = 1.2) is within a predetermined range where the knock signal amplitude value a exceeds the most frequent point A (for example, b, b ', b in FIG. 2).
It is a value for determining whether or not it is in the area "B".
If the knock signal amplitude value a exceeds the above range,
The most frequent point A is not updated.

In the following step 450, contrary to step 445, it is determined whether or not the knock signal amplitude value a is equal to or more than the product of the most frequent point A and the coefficient k2, and if a positive determination is made, the process proceeds to step 455. Here, the coefficient k2 (for example, k2 = 0.8) indicates whether or not the knock signal amplitude value a is within a predetermined range below the most frequent point A (for example, areas a, a ', a "in FIG. 2). It is determined whether or not the maximum frequency point A is not updated when the value is below this range.

That is, the processes of steps 445 and 450 described above are processes for determining whether or not the detected knock signal amplitude value a is in a constant update region including the most frequent point A, and only when it is in this range, The most frequent point A is updated in step 455 and the like.

Then, in step 455, in order to update the most frequent point A, it is determined whether or not the knock signal amplitude value a exceeds the most frequent point A. If an affirmative decision is made, the routine proceeds to step 460,
On the other hand, if a negative decision is made, the operation proceeds to step 465.

In step 460, the value 1 is added to the most frequent point A to perform the increase correction, and then the process proceeds to step 470. On the other hand, in step 465, the value 1 is subtracted from the most frequent point A to perform the reduction correction, and then the process proceeds to step 470.

In step 470, the process of storing various calculated or updated data in the RAM 3c or the backup RAM 3d is performed, and then this process is temporarily terminated.

As described above, according to the first embodiment, the knock signal amplitude value a obtained by A / D converting the peak hold value of the output signal of the knock sensor 31 is in the predetermined range that exceeds the most frequent point A. When the knock signal amplitude value a is in a predetermined range below the most frequent point A, the value 1 is subtracted from the most frequent point A to decrease the value. Correcting. As a result, the highest frequency point A
Therefore, the optimum most frequent point A can be set quickly and appropriately according to the operating state, and knocking can be accurately detected using this most frequent point A. . Furthermore, in order to calculate the most frequent point A,
Since it is not necessary to store a lot of data and statistically process it, it is possible to reduce the use area of the RAM3c etc. for storing data, and to reduce the calculation load of the statistical processing of the MPU3a. is there.

Further, since the highest frequency point A is used for calculating the knock determination level, even if the number of occurrences of knocking increases, the variation amount of the knock determination level is smaller than that when the frequency average value B is used, and stable knocking is achieved. Occurrence can be determined.

Next, a second embodiment of the present invention will be described in detail with reference to the drawings. The main difference between the second embodiment and the first embodiment is that this embodiment uses not only the most frequent points A but also the area average value (frequency average value) B of the frequency distribution to increase or decrease the occurrence of knocking. Accordingly, the knock determination level is switched to one based on the most frequent points A or one based on the frequency average value B for use. The rest of the device configuration is the same as that of the first embodiment, so the same parts are denoted by the same reference numerals and the description thereof is omitted.

The eighth most frequent point update process executed in the second embodiment is
A description will be given based on the flowchart in the figure. This processing is the same as the first embodiment, that is, knocking detection processing (step 500).
~ 520) and update processing of the most frequent points (steps 522-54)
4) consists of

First, in step 500, a process of reading various data is performed. In the following step 502, the A / D converted value A /
A process of setting D to the knock signal amplitude value a is performed.
Next, the process proceeds to step 504, and a process of outputting a peak hold end control signal to the peak hold circuit 3j is performed.

In the following step 506, it is determined whether or not the knock determination level K × B based on the frequency average value B exceeds the knock determination level k ′ × B × M based on the most frequent points A, and a positive determination is made. Proceed to step 508, while if negative determination is made, proceed to step 510. Here, the coefficient K is a coefficient for converting the frequency average value B into a knock determination level, and the coefficient k '
Is a coefficient set to a value slightly larger than the coefficient k of the first embodiment, and the coefficient M is a value A / calculated using the most frequently set point A and the frequency average value B set last time. B
Is.

In the determination of step 506, as shown in FIG. 13 described above, the knock determination level also changes depending on the knocking occurrence state, so the knock determination level K × B based on the frequency average value B and the most frequent point A are determined. This is a process for comparing the knock determination level k ′ × B × M based on the selected knock determination level and selecting the optimum knock determination level for detecting knocking. That is, when knocking occurs frequently, the routine proceeds to step 508, where the knock determination level k ′ × B × M based on the most frequent point A, which has little variation due to frequent knocking, is used. On the other hand, if knocking is small, the routine proceeds to step 510, where the knock determination level K × B based on the frequency average value B excellent in transient response is used.

In step 508, it is determined whether the knock signal amplitude value a is equal to or lower than the knock determination level k ′ × B × M based on the most frequent point A, it is determined that knocking has occurred, and it is determined that knocking has not occurred. If it is determined, the process proceeds to step 512, while if it is determined that knocking has occurred, the process proceeds to step 514.

In step 512, it is determined whether or not the count value of the counter n that counts the number of consecutive knock-free states is 10 or more. If the determination is affirmative, the process proceeds to step 516, whereas if the determination is negative, the process is step 518. Proceed to.

And, in the state where there is no knocking, continuous ignition cycle 10
In step 518 executed when the number of times is less than the number of times, the process of adding 1 to the count value of the counter n is performed, and then the step
Continue to 522.

On the other hand, in step 516 which is executed when the ignition cycle is 10 or more consecutive ignition cycles, the ignition timing advance correction value θ is advanced by the crank angle Y. Therefore, the target ignition timing θ
^* Is advanced by the crank angle Y. Continued Step 52
At 0, after performing the process of resetting the counter n to the value 0, the process proceeds to step 522.

Also, the steps that are executed when knocking occurs.
At 514, processing for retarding the ignition timing advance correction value θ by the crank angle X is performed. By this processing, the target ignition timing θ ^* is retarded by the crank angle X, and the occurrence of knocking is suppressed. Then, the process proceeds to step 522 via step 520.

Next, in this step 522, it is determined whether or not the frequency average value B is equal to or greater than the knock signal amplitude value a. If the affirmative determination is made, the routine proceeds to step 524, while if the negative determination is made, the routine proceeds to step 526. .

Then, if the frequency average value B is equal to or greater than the knock signal amplitude value a, it is determined in step 524 whether the frequency average value B is equal to the knock signal amplitude value a. Go to step 5 if not equal
At 28, the value 1 is subtracted from the frequency average value B to correct the decrease, and the routine proceeds to step 530.

On the other hand, if the frequency average value B is not greater than or equal to the knock signal amplitude value a, the value 1 is added to the frequency average value B in step 526 to increase the correction, and the process proceeds to step 530.

That is, when it is determined in steps 522 and 524 that the frequency average value B exceeds the knock signal amplitude value a measured this time, the frequency average value B is biased toward the larger knock signal amplitude value a. So step 528
Then, the frequency average value B is reduced and corrected by adding the data of this time. On the contrary, when the frequency average value B is lower than the knock signal amplitude value a, it means that the frequency average value B is biased toward the smaller knock signal amplitude value a. The increase correction is performed at 526.

In the following step 530, a process of setting a value obtained by multiplying the frequency average value B by the coefficient M as the temporary most frequent point b is performed.
That is, the provisional maximum frequency point b is set by multiplying the value A / B of the coefficient M by the frequency average value B of this time that has been corrected for decrease or increase.

In the following step 532, it is determined whether or not the knock signal amplitude value a is less than or equal to the product of the temporary most frequent point b and the coefficient k3 (for example, k3 = 1.2), and if an affirmative determination is made, the process proceeds to step 534. Then, in step 534, contrary to step 532, it is determined whether or not the knock signal amplitude value a is equal to or more than the product of the most frequent point A and the coefficient k4 (for example, k4 = 0.8), and an affirmative determination is made. Then, it proceeds to step 536.

That is, the processing of steps 532 and 534 is processing for determining whether or not the knock signal amplitude value a is within the range for updating the most frequent point A, as in the first embodiment.

In step 536, it is determined whether or not the knock signal amplitude value a exceeds the tentative maximum frequency point b. If the determination is affirmative, the process proceeds to step 538, whereas if the determination is negative, the process proceeds to step 540.

Then, in step 538 that is executed when the knock signal amplitude value a is on the side larger than the temporary most frequent point b, the value 0.01 is added to the coefficient M to perform the increase correction, and then the process proceeds to step 542. . On the other hand, in step 540, which is executed when the knock signal amplitude value a is on the side smaller than the temporary most frequent point b, the value 0.01 is subtracted from the coefficient M to perform the reduction correction, and then to step 542. move on.

That is, the processing in steps 538 and 540 is performed in step 53.
According to the determination based on the latest knock signal amplitude value a of 6,
The coefficient M for updating the most frequent points A is corrected by decreasing or increasing.

In the following step 542, the coefficient M corrected to the frequency average value B
Is multiplied by, and the value is set as the most frequent point A, and in the subsequent step 544, the value and various data are stored in the RAM 3c or the backup RAM 3d, and then this process is once terminated.

As described above, according to the second embodiment, in addition to the effects of the first embodiment described above, the following unique effects are exhibited.

In the second embodiment, the most frequent point A is obtained by using the coefficient M which is the ratio of the most frequent point A and the frequency average value B.
Even when the knock signal amplitude value a becomes large when the rotation of the engine 2 rises and the like, and the entire frequency distribution changes to a larger output, it is possible to sufficiently cope with the situation. That is, the frequency average value B updated using the maximum value of all knock signal amplitude values a is
Since the response corresponds to the frequency distribution that changes according to the operating state, the most frequent point A also changes, and it is possible to suitably follow the transient.

Furthermore, when knocking occurs frequently, the knock determination level based on the most frequent point A that is stable against change is used, while when knocking occurs less, the transient response is excellent. Since the knock determination level based on the frequency average value B is used, the knock determination level can be appropriately switched according to the knocking occurrence state, and the occurrence of knocking can be accurately detected.

As the process (steps 445 to 470) for updating the most frequent points A in the first embodiment, the process (steps 522 to 544) for updating the most frequent points A in the second embodiment may be adopted. On the contrary, as the process (steps 522 to 544) for updating the most frequent point A in the second embodiment,
The process (steps 445 to 470) of updating the most frequent point A in the first embodiment may be adopted. That is, the update processing of the most frequent points A in the first embodiment has an advantage that the calculation is simple, and the update processing of the most frequent points A in the second embodiment has an advantage that it has excellent responsiveness at the transition. Since there is, you can choose either feature.

Next, a third embodiment and a fourth embodiment will be described. The third embodiment and the fourth embodiment are the same as the first embodiment or the second embodiment.
A major difference from the embodiment is that the most frequent point A is divided into an area for increasing correction and an area for decreasing correction, and each area is divided into a large correction area and a small correction area.

First, the most frequent point updating process of the third embodiment will be described with reference to the flowchart of FIG.

In step 600, a process of reading various data is performed. In the following step 605, the A / D conversion value A / D is
A process of setting the knock signal amplitude value a is performed. Next, in step 610, a process of outputting a peak hold end control signal to the peak hold circuit 3j is performed.

In the following step 615, it is determined whether or not the most frequent point A obtained up to the previous time is the knock signal amplitude value a or more,
If an affirmative decision is made, the operation proceeds to step 620, while if a negative decision is made, the operation proceeds to step 625. In step 620, it is determined whether the most frequent point A is equal to the knock signal amplitude value a,
If they are equal, proceed to step 655, while if they are not equal proceed to step 630.

In this step 630, it is determined whether or not the knock signal amplitude value a is less than the product of the most frequent point A and the coefficient k5 (for example, k5 = 0.8), and if an affirmative decision is made, the routine proceeds to step 635, while
If a negative decision is made, the operation proceeds to step 640. This Step 635
Then, the value 1 is subtracted from the most frequent point A to perform the reduction correction, and then the process proceeds to step 655. Meanwhile, step 640
Then, after the value 2 is subtracted from the most frequent point A to perform the reduction correction, the process proceeds to step 655.

Further, in step 625, it is determined whether or not the knock signal amplitude value a exceeds the product of the most frequent point A and the coefficient k6 (for example, k6 = 1.2). If an affirmative determination is made, the processing proceeds to step 645, while If a negative decision is made, the operation proceeds to step 650. In this step 645, the value 1 is added to the most frequent point A to perform the increase correction, and then the process proceeds to step 655. on the other hand,
In step 650, the value 2 is added to the most frequent point A to perform the increase correction, and then the process proceeds to step 655.

Here, in the processing of steps 615 to 650, as shown in FIG. 10, it is first determined whether the knock signal amplitude value a is in the left or right area of the most frequent point A obtained up to the previous time, and the decrease is performed. It is determined whether to perform correction or increase correction. Subsequently, it is determined whether or not the knock signal amplitude value a is in a predetermined range (C, D in the figure) indicated by the diagonal lines in FIG. 10, and the update amount of the most frequent point A is set to 2 within that range. In the case of the outside area (e.g., (e) and (e) in the figure) that is made larger than that area, the update amount is set to be as small as 1.

In the following step 655, it is determined whether or not the knock signal amplitude value a is equal to or lower than the knock determination level k × A for determining the occurrence of knocking. If an affirmative determination is made, the processing proceeds to step 660, while if a negative determination is made. Go to step 665.

Steps to be performed when knocking is not occurring
In 660, it is determined whether or not the count value of the counter n that counts the number of continuous knocking-free states is 10 or more. If an affirmative determination is made, the routine proceeds to step 670, while if a negative determination is made, the routine proceeds to step 675. .

In step 675, which is executed when the knocking-free state is less than 10 consecutive ignition cycles, the value 1 is added to the count value of the counter n, and then the process proceeds to step 685.

On the other hand, in step 670, which is executed when the ignition cycle is 10 or more consecutive ignition cycles, the ignition timing advance correction value θ is advanced by the crank angle Y.

In the following step 680, the process of resetting the counter n to the value 0 is performed, and then the process proceeds to step 685. Further, in step 665 executed when knocking occurs, a process of retarding the ignition timing advance correction value θ by the crank angle X is performed in order to suppress knocking. Then, the process proceeds to step 685 via step 680.

In this step 685, a process of storing various calculated or updated data in the RAM 3c or the backup RAM 3d is performed, and then this process is temporarily terminated.

As described above, according to the third embodiment, the area where the most frequent point A is increased and the area where the most frequent point A is decreased are divided into two areas.
The area is divided into two areas, and the update amount in the area closer to the most frequent point A is set larger (double) than the update amount in the far area. In this way, by setting different update amounts, even when the knock signal amplitude value a greatly changes during the transition, the most frequent point A is quickly updated according to the change in the operating state, and the knock determination level is thereby updated. Can be changed to appropriately detect the occurrence of knocking. In other words, in the present embodiment, since the update is performed not only in a partial area but in the entire area, the most frequent point A is quickly updated, and the followability is excellent. Further, since the update amount of the area close to the most frequent point A is large, there is an advantage that the most frequent point A is prevented from excessively changing and the convergence is excellent.

Furthermore, when the above-mentioned coefficient M is used, when the operating state changes suddenly, the statistical distribution also changes greatly, so in some cases guarding is required and the calculation of the most frequent points A must be redone from the beginning. However, in this embodiment, since the most frequent point A is changed quickly over the entire area,
There is an effect that the possibility of being guarded is reduced and the calculation is simplified.

Next, a fourth embodiment will be described with reference to FIGS. 11 and 12.

The major difference of the fourth embodiment from the third embodiment is that the update amount of the most frequent point A is changed according to the change of the engine speed. And guards are applied to prevent this amount of change from becoming too large.

First, regarding the guard value update processing in the present embodiment,
Description will be given based on the flowchart of FIG. This process is 20
It is executed by an interrupt every 0 msec.

In step 700, the current engine speed Nnew is subtracted from the previous engine speed Nold obtained based on the signal from the rotation speed sensor 33, and the absolute value of 1/50 of the difference is set as the correction value d. The reason for dividing by 50 here is that if the difference in engine speed is simply used, the update amount becomes too large, and the most frequent point A cannot be obtained suitably.

Next, at step 710, the current engine speed Nnew is set to the previous engine speed Nold.

In the following step 720, in order to update the guard value C for checking the correction value d, it is determined whether or not the correction value d is equal to or more than the previously set guard value C, that is, whether or not the change in the engine speed is large. If the affirmative judgment is made, the routine proceeds to step 730, while if the negative judgment is made, the routine proceeds to step 740. Then, in step 730, the correction value d is set to the guard value C on the assumption that the change in the engine speed has increased, while on the other hand, in step 740, the guard value is considered to have converged on the change in the engine speed. Correct the value C to 1/2 of it.

That is, in the present process, the guard value C is increased when the amount of change in the engine speed is large, but the guard value C is decreased when the amount of change is small.
In this embodiment, the engine speed change is 50 rpm / 200.
In msec or less, d <1 and d = 0 due to cancellation of digits, so C = 0. Therefore, the calculated most frequent points A when there is no change in rotation converges to the most statistically frequent points A.

Next, regarding the most frequent point update processing in the present embodiment,
Description will be given based on the flowchart of FIG.

At step 800, a process of reading various data is performed. In the following step 805, the A / D conversion value A / D is
A process of setting the knock signal amplitude value a is performed. Next, proceeding to step 810, a process of outputting a peak hold end control signal to the peak hold circuit 3j is performed.

In the following step 815, the correction value d is set to the absolute value of 1/4 of the difference between the most frequent point A and the knock signal amplitude value a. This is a so-called 1/4 smoothing process, and when the knock signal amplitude value a is small, it is unnecessarily the most frequent point A.
Is not updated.

In step 820, it is determined whether or not the correction value d is less than or equal to the guard value C, and if an affirmative determination is made here, the process proceeds to step 830, while if a negative determination is made, the process proceeds to step 825 to set the value of the guard value C. Set as the correction value d. That is, when it is determined in step 820 that the correction value d is not less than or equal to the guard value C, the correction value d is set using the guard value C obtained in the processing of FIG. 11 described above.

In the following step 830, it is determined whether or not the most frequent point A obtained up to the previous time is the knock signal amplitude value a or more,
If the affirmative judgment is made, the routine proceeds to step 835, while if the negative judgment is made, the routine proceeds to step 840. In step 835, it is determined whether the most frequent point A is equal to the knock signal amplitude value a,
If they are equal, proceed to step 870, while if they are not equal proceed to step 845.

In this step 845, it is determined whether or not the knock signal amplitude value a falls below the product of the most frequent point A and the coefficient k7 (for example, k7 = 0.8). If an affirmative decision is made, the routine proceeds to step 855, while a negative decision is made. And proceed to step 850. And step 850
Then, after the value 1 is subtracted from the most frequent point A to perform the reduction correction, the process proceeds to step 855.

In this step 855, a value obtained by subtracting the correction value d from the most frequent point A is set as the most frequent point A. That is, in steps 845 to 855, in the predetermined range in which the knock signal amplitude value a is far from the most frequent point A (for example, the area of E in FIG. 10), the most frequent point A is only reduced and corrected by the correction value d. However, in a predetermined range in which the knock signal amplitude value a is close to the most frequent point A (for example, the area C in FIG. 10), a large decrease correction is performed by subtracting the value 1 and the correction value d from the most frequent point A. It will be.

Further, in step 840, it is determined whether or not the knock signal amplitude value a exceeds the product of the most frequent point A and the coefficient k8 (for example, k8 = 1.2), and if an affirmative decision is made, the routine proceeds to step 865, while a negative decision is made. If it is determined, the process proceeds to step 850. In this step 860, the value 1 is added to the most frequent point A to perform the increase correction, and then the process proceeds to step 865. Step 8
At 65, a value obtained by subtracting the correction value d from the most frequent point A is set as the most frequent point A. That is, steps 840,860,865
Contrary to steps 845 to 855, in the predetermined range in which the knock signal amplitude value a is far from the most frequent point A (for example, the area shown in FIG. 10), the most frequent point A is increased and corrected by the correction value d. However, within a predetermined range (for example, the second area in FIG. 10) where the knock signal amplitude value a is close to the most frequent point A,
A large increase correction in which the value 1 and the correction value d are added to the most frequent point A is performed.

In the following step 870, the process of storing the data in the RAM 3C or the like is performed, and then this process is once terminated.

As described above, according to the fourth embodiment, in addition to the effect that the maximum frequency point A is excellent in convergence as in the third embodiment, the maximum frequency point A is increased according to the engine speed. Since the correction value d of is changed, the followability during the transition is excellent. Furthermore, the guard value C is set according to the engine speed.
Is changed and set, it is possible to set a suitable guard value C during a transition. As a result, the most frequent point A can be adjusted appropriately, and a large knock or an erroneous retardation can be prevented.

Although some embodiments of the present invention have been described above, the present invention is not limited to these embodiments and can be implemented in various modes without departing from the scope of the present invention. Of course.

Effects of the Invention As described in detail above, the knocking control device for an internal combustion engine of the present invention, when the maximum value of the knock signal is in a predetermined range exceeding the most frequent points, adds a predetermined value to the maximum frequency points,
Moreover, when the maximum value of the knock signal is within the predetermined range below the most frequent point, the predetermined value is subtracted from the maximum frequency point and updated. Therefore, it is possible to easily calculate the update of the most frequent points and reduce the load on the processing device. That is, since a large-scale storage capacity and high-speed arithmetic processing capacity are not necessarily required, it can be realized with a relatively simple device configuration, and versatility and vehicle mountability can be improved.

Further, the difference between the most frequent points when knocking occurs and when the knocking does not occur is relatively small, and since the knock determination level for detecting occurrence of knocking does not fluctuate significantly, the reliability of the knocking control device increases, and based on the detection result. When the knocking suppression control is effectively executed, the durability of the internal combustion engine is enhanced.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram conceptually illustrating the content of the present invention, FIG. 2 is a graph for explaining the operation of the present invention, and FIG. 3 is a system configuration diagram of the first embodiment, FIGS. 5, 6 and 7 are flowcharts showing the same control, FIG. 8 is a flowchart showing control of the second embodiment, FIG. 9 is a flowchart showing control of the third embodiment, and FIG. A graph showing the relationship between the knock signal amplitude value and the occurrence frequency,
FIG. 11 is a flow chart showing the guard value updating process of the fourth embodiment, FIG. 12 is a flow chart showing the most frequent point updating process, and FIG. 13 is a graph for explaining the prior art. M1 ...... Internal combustion engine M2 ...... Knock signal detection means M3 ...... Maximum frequency point calculation means M4 ...... Knock determination means M5 ...... Maximum frequency point addition update means M6 ...... Maximum frequency point subtraction update means 1 ...... Engine knocking Control unit 2 …… Engine 3 …… Electronic control unit (ECU) 3a …… MPU 31 …… Knock sensor

Claims (1)

[Claims] 1. A knock signal detecting means for detecting a mechanical vibration of an engine body of an internal combustion engine to output a knock signal, and a maximum frequency point of a maximum value of a knock signal outputted by the knock signal detecting means in a knock detecting period. And a knock determining means for calculating a knock determination level based on the most frequent points obtained by the most frequent point calculating means, and a knock determining means for determining occurrence of knocking using the knock determining level, In a knocking control device for an internal combustion engine provided, in the case where the maximum value of the knock signal detected by the knock signal detecting means is in a predetermined range exceeding the most frequent point, a predetermined value is added to the maximum frequency point. And the maximum value of the knock signal detected by the knock signal detection means is less than the predetermined frequency. When in the circumference, the knock control apparatus for an internal combustion engine characterized by comprising a maximum frequency point subtraction update means for updating by subtracting a predetermined value from said maximum frequency point, the.