JPH0536634B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a knocking control method for an internal combustion engine, and more particularly to a corrected retard amount for retarding the engine at a relatively fast speed depending on the presence or absence of knocking, and a retardation amount for retarding the engine at a relatively slow speed depending on the presence or absence of knocking. The present invention relates to a method for controlling knocking by correcting the basic ignition advance angle using a learning retardation amount that is changed by learning control. The conventional knocking control method using learning control is
The basic ignition advance angle θ _BASE , which is predetermined by the load determined by the engine speed N, the ratio Q/N of the intake air amount Q and the engine speed N, or the intake pipe negative pressure, is stored in the read-on memory (ROM) of the microcomputer. It is stored in the form of a map, calculates the ignition advance angle θ _ig for actually controlling the igniter based on the following equation (1), and performs knocking control using this ignition advance angle. θ _ig = θ _BASE − (θ _KG + θ _K ) ...(1) However, θ _KG is determined by the engine speed and load and is changed by learning control in order to keep the knocking level at a predetermined level. The learned retard amount θ _K is a corrected retard amount that retards the ignition timing when knocking occurs and advances the ignition timing when knocking no longer occurs. Here, the corrected retard amount θ _K is obtained as follows. First, engine vibration is detected using a knocking sensor composed of a microphone, etc., and a predetermined times K・b (where K is a proportionality constant) of the average value (background) of engine vibration b is calculated as the peak of engine vibration. The peak value a is then compared with the value of K·b. When the peak value a exceeds the value of K・b, it is determined that knocking has occurred, and the ignition timing is corrected so that the ignition timing is delayed by a predetermined crank angle (for example, 0.4℃A) for each knocking occurrence, as shown in the following equation (2). Change the retard amount θ _K. θ _K ←θ _K +0.4°CA ...(2) Also, when the peak value a is less than the value of K・b,
After determining that no knocking has occurred, the first timer is used to determine whether a predetermined time (for example, 48 msec) has elapsed, and when the predetermined time has elapsed, the crank angle is adjusted to a predetermined crank angle as shown in the following equation (3). (for example
0.08°CA) Change the correction retard amount θ _K so that the ignition timing advances. θ _K ← θ _K −0.08°CA (3) Further, the learning retardation amount θ _KG according to the engine conditions is calculated as follows. First, as shown in Fig. 1, addresses 0 to 23 for storing learning retard amounts in correspondence with engine speed N and load Q/N are prepared in the random access memory (RAM) of a microcomputer, and a learning map is created. Create it.
The engine speed N and intake air amount Q are taken in, and the RAM addresses of four points surrounding the point (N, Q/N) indicating the current engine condition on the learning map are found. Now, as shown in Figure 2, the enclosing points indicating the current engine conditions are located at RAM address n (n=0, 1,
...16), n+1, n+6, n+7, and address n
Learning retardation amount θ _KGo at address n+1, learning retardation amount θ _KG(o+1) at address n+6, learning retardation amount θ _KG(o+3) at address n+7, learning retardation amount θ _KG(o+) at address n+7. ₇₎ are respectively memorized. Then, the difference in engine speed between addresses is X, the difference in load between addresses is Y, the difference in engine speed between address n and the point indicating the current engine condition is x, and the difference between address n and the current engine If the difference in load between the point indicating the condition and the point indicating the condition is y, then the learning retard amount θ _KG of the point indicating the current engine condition is determined by the two-dimensional interpolation method shown in equations (4) to (6) below. It will be done. A=x(θ _KGo −θ _KG(o+1) )/X+θ _KGo …(4) B=x(θ _KG(o+6) −θ _KG(o+7) )/X +θ _{KG(o+ 6)} ...(5) θ _KG =y(A-B)/Y+A...(6) And the learning control of the learning map is performed as follows. First, a second timer that determines the learning control time depending on the current engine condition and a third timer that determines the learning control time regardless of the engine condition are prepared. When the second timer detects that a predetermined time (for example, 48 msec) has elapsed, it is determined whether the correction retard amount θ _K has been changed to exceed a predetermined crank angle (for example, 4° CA), and the correction delay When the angle θ _K exceeds a predetermined crank angle, a predetermined crank angle (for example, 0.004° CA) is added to the learning retard amounts at the four points on the learning map surrounding the point indicating the current engine condition explained above. .
As a result, the learning retard amount is learning-controlled so that the ignition timing is delayed. On the other hand, when the third timer detects that a predetermined period of time (for example, 16 seconds) has elapsed, a predetermined crank angle (for example, 0.01° CA) is calculated from the learning retard amount of all addresses on the learning map, regardless of the presence or absence of knocking. By subtracting the value, the learning retard amount is controlled to advance the ignition timing. Using the corrected retardation amount θ _K changed as described above and the learning retardation amount θ _KG obtained by the two-dimensional interpolation method from the learning map subjected to learning control,
Knocking is controlled by correcting the basic ignition advance angle θ _BASE based on equation (1). By the way, as shown in Fig. 3, the basic ignition advance angle θ _BASE , or MBT (Minimum Spank Advance
For Best Torque) changes as shown by curve C ₁ depending on the engine speed. In addition, the ignition timing at which minute knocking occurs when knocking is difficult to occur, such as when the air is humid, is as shown by curve C ₂ , and the ignition timing at which minute knocking occurs when knocking is likely to occur, such as when the air is dry. The ignition timing will be as shown in curve _C3 . Therefore, the ignition timing at which minute knocking occurs varies depending on the engine speed and environmental conditions. In the knocking control method using learning control as described above, when a predetermined period of time has elapsed, the entire learning retard amount is independently changed to the advance side by learning control, regardless of the presence or absence of knocking. Under engine conditions where there are few opportunities for learning control, the learning retard amount becomes too advanced, resulting in knocking. In addition, as mentioned above, since the learning retardation amount tends to be learned and controlled to the advance side, the learning control speed for controlling the ignition timing to the advance side cannot be set quickly, and as shown in Figure 3 above. When the engine conditions change and knocking becomes less likely to occur, as in the case shown in , the ignition timing may be retarded too much due to the learned retardation amount, making it impossible to obtain pest torque in the range where knocking does not occur. There was a problem. The present invention has been made to solve the above problems, and an object of the present invention is to provide a knocking control method that can always perform knocking control in the same way under conditions where knocking is likely to occur and under conditions where knocking is unlikely to occur. In order to achieve the above object, the configuration of the present invention provides a correction retard amount that is added or subtracted from the basic ignition advance angle determined by the engine speed and load depending on the presence or absence of knocking, and a level of knocking to a predetermined level. Knocking is controlled by subtracting the sum of the learned retardation amount, which is determined by the engine speed and load and is rewritten when the magnitude of the corrected retardation amount is out of a predetermined range. In the knocking control method for an internal combustion engine, the learning control of the learning retard amount is stopped in an area where the engine rotational speed is less than a predetermined rotational speed on the low rotational side, and the learning control of the learning retard amount is stopped in an area where the engine rotational speed is higher than the predetermined rotational speed. The learned retard amount is controlled in a learning manner so that the corrected retard amount falls within a predetermined range. Here, in order to solve the above problem, the learned retard amount is controlled so that the corrected retard amount θ _K takes a value within a predetermined range (for example, 2° CA ≦ θ _K ≦ 4° CA). It is conceivable to always perform knocking control in the same way under conditions where knocking is unlikely to occur and under conditions where knocking is likely to occur. However, in a region where the engine speed is low, the S/N ratio is poor, so it may not be possible to distinguish between the knocking judgment level and the noise level, and the corrective retardation amount is changed due to incorrect knocking detection, resulting in a poor S/N ratio. Since learning control is applied to the bad low engine speed region, there is a problem that the learning retard amount in the region close to the bad low engine speed region with S/N may show an abnormal value due to the learning control. Occur. According to the configuration of the present invention, since the learning control is not performed in the low engine speed range and the learning value in the slightly higher engine speed side is used, the learned value in the low engine speed range may be affected by electrical and mechanical noise. This has the unique effect of preventing the engine from becoming abnormal, ensuring good learning control, and preventing a decrease in output and a deterioration in heating costs due to occurrence of knocking or excessive retardation. Next, FIG. 4 shows an example of an engine to which the present invention is applied. As shown in the figure, this engine is equipped with an air flow meter 2 as an intake air amount sensor provided downstream of an air cleaner (not shown). The air flow meter 2 includes a compensation plate 2A rotatably provided in the damping chamber and a potentiometer 2B that detects the opening degree of the compensation plate 2A.
It is composed of. Therefore, the intake air amount Q is detected as the voltage output from the potentiometer 2B. Further, an intake air temperature sensor 4 is provided near the air flow meter 2 to detect the temperature of intake air. A throttle valve 6 is arranged downstream of the air flow meter 2, and downstream of the throttle valve 6,
A surge tank 8 is provided. An intake manifold 10 is connected to the surge tank 8, and a fuel injection valve 12 is disposed protruding into the intake manifold 10. The intake manifold 10 is an engine main body 14
The combustion chamber 1 of the engine is connected to the fuel chamber 14A of the engine.
4A is connected via an exhaust manifold 16 to a catalytic converter (not shown) filled with a three-way catalyst. The engine body 14 is provided with a knocking sensor 18 configured with a microphone or the like to detect vibrations of the engine. In addition, 20 is a spark plug, 22 is an O ₂ sensor for controlling the air-fuel mixture near the stoichiometric air-fuel ratio, 2
4 is a cold/hot water temperature sensor that detects the engine cooling water temperature. The spark plug 20 of the engine body 14 is connected to a distributor 26, and the distributor 26 is connected to an igniter 28. The distributor 26 is provided with a cylinder discrimination sensor 30 and an engine rotation angle sensor 32, which are comprised of a pickup and a signal rotor fixed to the distributor shaft.
This cylinder discrimination sensor 30 is configured to detect, for example, a crank angle.
A cylinder discrimination signal is output every 720 degrees to an electronic control circuit 34 composed of a microcomputer, etc., and this engine rotation angle sensor 32 detects, for example, a crank angle.
A crank angle reference position signal is output to the electronic control circuit 34 every 30 degrees. As shown in FIG. 5, the electronic control circuit 34 includes a random access memory (RAM) 36, a read only memory (ROM) 38, a central processing unit (CPU) 40, and a clock (CLOCK).
41, a first input/output port 42, a second input/output port 44, a first output port 46, a second
RAM3
6, ROM38, CPU40, CLOCK41, 1st
an input/output port 42, a second input/output port 44,
First output port 46 and second output port 4
8 are connected by a bus 50. The first input/output port 42 includes a buffer (not shown) multiplexer 54, an analog-digital (A/
D) air flow meter 2 via transducer 56;
A cooling water temperature sensor 24, an intake air temperature sensor 4, etc. are connected. The multiplexer 54 and A/D converter 56 are controlled by a signal output from the first input/output port 42. The O ₂ sensor 22 is connected to the second input/output port 44 via a buffer (not shown) and a comparator 62, and the cylinder discrimination sensor 30 and engine rotation angle sensor 32 are connected via a waveform shaping circuit 64. ing. The second input/output port 44 also includes a bandpass filter 60 and a peak hold circuit 6.
1. The knocking sensor 18 is connected via a channel switching circuit 66 and an A/D converter 68. This bandpass filter is connected to a channel switching circuit 66 via an integrating circuit 63. This channel switching circuit 66 receives a control signal output from the second input/output port 44 for inputting either the output of the peak hold circuit 61 or the output of the integrating circuit 63 to the A/D converter 68. is input to the peak hold circuit 61, and a reset signal is input to the peak hold circuit 61 from the second input/output port 44. Further, the first output port 46 is connected to the igniter 28 via the drive circuit 70,
Second output port 48 is connected to fuel injector 12 via drive circuit 72 . The ROM 38 of the electronic control circuit 34 stores in advance a map of the basic ignition advance angle θ _BASE expressed by the engine speed and intake air amount, the basic fuel injection amount, etc. The basic ignition advance angle and the basic fuel injection amount are read by the signal from the angle sensor 32, and the basic ignition advance angle and the basic fuel injection amount are read by various signals including the signals from the cooling water temperature sensor 24 and the intake air temperature sensor 4. The corrected ignition advance angle and corrected fuel injection amount are added to the amount, and the igniter 28
and the fuel injection valve 12 are controlled. The air-fuel ratio signal output from the O ₂ sensor 22 is used for air-fuel ratio control to control the air-fuel ratio of the air-fuel mixture to near the stoichiometric air-fuel ratio. Further, a learning map shown in FIG. 1 is stored in advance in the RAM 36 of the electronic control circuit 34. Next, an embodiment in which the present invention is applied to the engine as described above will be described in detail. In addition,
In explaining the embodiments of the present invention, the main routines of fuel injection control, air-fuel ratio control, ignition timing control, etc. are the same as conventional ones, so explanations will be omitted, and the routine of knocking control related to the present invention will be omitted. will be explained only. FIG. 6 shows an interrupt routine every 30° CA when the present invention is implemented using a microcomputer. First, in step 81, the engine rotation speed N is calculated from the rotation time based on the signal from the engine rotation angle sensor 32, and in step 82, the number of interruptions after the cylinder discrimination signal is input from the cylinder discrimination sensor 30 is counted. Sets a flag indicating the current crank angle. Next, in step 83,
It is determined whether the flag set in step 82 is a top dead center (TDC) flag. If it is not currently the top dead center, the process advances to step 88, and if it is currently the top dead center, it is determined in step 84 whether or not the knock gate is closed. If the lock gate is open, the lock gate is closed in step 85, and if the lock gate is closed, the lock gate is closed in step 86.
At this point, the channel switching circuit 66 is switched, and the engine vibration signal output from the knocking sensor 18 is input to the A/D converter 68 via the bandpass filter 60, the integrating circuit 63, and the channel switching circuit 66, and the engine vibration signal is input to the A/D converter 68. A/D conversion of the average value or background level is started. Subsequently, in step 87, the closing time t ₁ of the knock gate, that is, the time when the next knock gate will be closed, is calculated and a time coincidence interrupt A is set. Next, in step 88, based on the flag set in step 82, it is determined whether the crank angle has reached 90° CA BTDC (before top dead center). The crank angle
If it is not 90°CA BTDC, proceed to step 91.
In the case of 90° CA BTDC, in step 89, the corrected advance angle amount θ _K is updated and the ignition timing is calculated (details of this will be explained below).
In step 90, the time to turn on the igniter 28 is determined based on the ignition timing calculated in step 89 and the current time, and a time coincidence interrupt B is set, and an igniter-on flag is set. Then, in step 91, the crank angle is 60° CA.
Determine whether it has become BTDC or not, 60°CA BTDC
If not, return to the main routine,
If it is 60° CA BTDC, the igniter off time is calculated in step 92, a time coincidence interrupt B is set, and the igniter on flag set in step 90 is removed. Next, the timing coincidence interrupt A shown in FIG. 7 will be explained. This interrupt routine is to find the peak value of engine vibration, and is performed using the steps shown in Figure 6.
When the time set in 87 is reached, an interrupt is generated.
In step 93, the peak value held in the peak hold circuit 61 is input to the A/D converter 68 via the channel switching circuit 66, A/D conversion of the peak hold value is started, and the process returns to the main routine. FIG. 8 shows the routine of time coincidence interrupt B, which includes step 90 and step 90 of FIG.
At the time set to 92, an interrupt will occur. In step 94, it is determined whether the igniter on flag is on, that is, whether this flag is 1. If the flag is on, the igniter is turned on in step 96, and if the flag is off, the igniter is turned on in step 95. Turn off and return to the main routine. FIG. 9 shows the A/D conversion completion interrupt routine.
This interrupt occurs when the conversion and A/D conversion of the peak hold value is complete. First, in step 97, it is determined whether the knock gate is currently open. When the check gate is closed, in step 98, the A/D conversion value converted in step 86 of FIG.
At 99, open the knock gate and return to the main routine. On the other hand, when the knock gate is open, the A/
The D-converted value is stored in the memory of the RAM 36 as the peak value a, the check gate is closed in step 101, and the process returns to the main routine. FIG. 10 shows an interrupt routine performed every predetermined time (for example, 4 msec) for counting the time when no knocking occurs and the time for learning control. First, step
In step 102, the count value of counter TIME1, which determines the time when no knocking occurs, is incremented by one, and in step 103, the count value of counter TIME2, which determines the time for learning control, is incremented by one. In the next step 104, the counter
It is determined whether the count value of TIME1 is 12 (48 msec) or less. If the count value exceeds 12, the counter is
The count value of TIME1 is 12, and the count value is 12
The counter is set in step 106 in the following cases.
Determine whether the count value of TIME2 is 12 or less. Here, if the count value exceeds 12, the counter is
The count value of TIME2 is set to 12 and the process returns to the main routine. When the count value is 12 or less, the process returns to the main routine. Next, the detailed routine of step 89 in FIG. 6 will be explained based on FIG. 11. When it is determined in step 88 of FIG. 6 that the crank angle has reached 90° CA BTDC, the load Q/N is reduced to 0.6 in step 122.
It is determined whether or not it is greater than [/rev.], that is, whether it is in the knocking control region. If it is not in the knocking control region, the basic ignition advance angle θ _BASE is set to ignition advance angle θ _ig in step 123, and if it is in the knocking control region, in step 108, step 100 in FIG.
The peak value a stored in step 98 of FIG.
A constant K is added to the background level b stored in
The value obtained by multiplying by K·b is compared. When the peak value a exceeds the value K·b, it is determined that knocking has occurred, and in step 110, the correction retard amount θ _K is increased by a predetermined angle (for example, 0.4° CA), and in step 112, no knocking occurs. Clear the count value of the counter TIME1 that counts time. On the other hand, when the peak value a is less than the value K・b, it is determined that knocking will not occur, and the step
In step 109, it is determined whether the count value of the counter TIME1 is greater than or equal to a predetermined value (12), and if the count value is greater than or equal to the predetermined value, it is determined that the state in which knocking does not occur has continued for a predetermined period of time. After decreasing the corrected retard amount θ _K by a predetermined angle (for example, 0.08° CA) in step 111, the counter TIME1 is cleared in step 112. Also, step
If the count value is less than the predetermined value in step 109, the process advances to step 113. In step 113, the correction retardation amount θ _K obtained as described above and the learned retardation amount θ _KG obtained from the learning map by the two-dimensional interpolation method are used to calculate the basic equation as shown in equation (1) above. The ignition advance angle θ _BASE is corrected to calculate the ignition advance angle θ _ig that actually controls the igniter. Next, a routine for determining the learning retard amount θ _KG corresponding to the current engine conditions from the learning map and performing learning control will be explained. FIG. 12 shows this routine from the middle of the main routine. First, in step 124, the load Q/N is 0.6
It is determined whether or not it is greater than [/rev.], that is, whether it is in the knocking control region. If it is not the knocking control area, the main routine continues as is, and if it is the knocking control area, in step 114, the RAM addresses of the four points surrounding the point indicating the current engine condition determined by the engine speed N and the load Q/N are stored. Find it on the learning map. Next, in step 115, a two-dimensional interpolation method (two-dimensional interpolation method (The routine will be explained later) calculates the learning retardation amount θ _KG at the point indicating the current engine condition, and stores the calculated value in a predetermined location in the RAM.
In the next step 124, it is determined whether the engine speed N is equal to or higher than a predetermined low speed (for example, 1500 [rpm]).If the engine speed is less than the predetermined speed, no learning control is performed and the main Returning to the routine, if the engine speed is equal to or higher than the predetermined speed, the process proceeds to the next step 116. In step 116, the count value of the counter TIME2 for determining the learning control time counted in step 103 of FIG. Predetermined value (e.g. 12)
Determine whether or not the above is true. If the count value is less than the predetermined value, the process returns to the main routine, and if the count value is greater than or equal to the predetermined value, the count value of counter TIME2 is cleared in step 117, and then
The corrected retardation amount θ _K updated in steps 110 and 111 in FIG.
In step 118, it is determined whether or not the temperature is greater than or equal to 2° CA. If it is determined in step 118 that the corrected retardation amount θ _K is less than the first predetermined crank angle, then in step 121 the retardation amount θ K is stored in four points on the learning map surrounding the point indicating the current engine condition. A predetermined crank angle (for example,
0.04°CA) Performs subtraction learning control and returns to the main routine. As a result, the corrected retardation amount θ _K
is less than the first predetermined crank angle, learning control is performed so that the learning retardation amount of the learning map becomes smaller, and the ignition timing is controlled to advance by the learning retardation amount. On the other hand, in step 118, the corrected retardation amount θ _K
is determined to be greater than or equal to the first predetermined crank angle, in step 119 the corrected retard amount θ _K is set to a second predetermined crank angle (for example, 4° CA) that is larger than the first predetermined crank angle. Determine whether the value is less than or equal to the value. If it is determined in step 119 that the corrected retard amount θ _K is less than the first predetermined crank angle, that is, if the corrected retard amount θ _K satisfies the following conditions, the first predetermined crank angle ( 2°CA)≦ _θK <second predetermined crank angle (4°CA)...(7) Return to the main routine without learning control. As a result, when the corrected retard amount θ _K takes a value within a predetermined range, learning control is not performed, and the ignition timing is not changed depending on the learned retard amount. Note that even when the corrected retard amount takes a value within a predetermined range, learning control may be performed as necessary. If it is determined in step 119 that the corrected retardation amount θ _K is greater than or equal to the second predetermined crank angle, then in step 120 the learning retardation amount stored in the four points on the learning map surrounding the point indicating the current engine condition is Learning control is performed to add a predetermined crank angle (for example, 0.04° CA) to each angle amount, and the process returns to the main routine. As a result, when the corrected retardation amount θ _K is equal to or greater than the second predetermined crank angle, learning control is performed so that the learning retardation amount of the learning map becomes larger, and the ignition timing is controlled to be delayed by the learning retardation amount. be done. By performing the learning control as described above, the learning retardation amount of the learning map is changed so that the corrected retardation amount falls within a predetermined range, and the engine speed is increased to 1500.
Learning control is not performed below [rpm] (region to the left of the dashed-dotted line in FIG. 1). Below are the steps 115 of the learning routine in Figure 12.
The detailed routine of the two-dimensional interpolation method in
This will be explained using figures. In this two-dimensional interpolation routine, the map shown in Figure 1 is used as a learning map, and four points representing the current engine conditions are used.
As shown in Figure 2, the RAM addresses are n, n+1,
Let n+6 and n+7. First, in step 130, it is determined whether the current load Q/N is less than the upper limit of the load on the learning map, that is, 1.2 [/rev.]. If the load exceeds 1.2 [/rev.], 1.2 is stored in register n in step 131, and if the load is less than 1.2 [/rev.], the current load Q/N is stored in step 134. value in register n
to be memorized. In step 135, it is determined whether the current engine speed N is less than or equal to the upper limit of the engine speed on the learning map, that is, 6000 [rpm]. If the engine speed exceeds 6000 [rpm], 6000 is stored in register m in step 136, and if the engine speed is below 6000 [rpm], the current engine speed N is stored in step 137.
stores the value in register m. In step 138,
It is determined whether the value of register n is greater than or equal to the lower limit of the load on the learning map, that is, 0.6 [/rev.], and if the value of register n is less than 0.6, the value of register n is set to 0.6 in step 139. , if the value of register n is 0.6 or more, step 140
Proceed to. Then, in step 140, it is determined whether the value of register m is greater than or equal to the lower limit value of the engine rotation speed on the learning map, that is, 1000 [rpm], and if the value of register m is less than 1000, step 140 is performed.
141, the value of register m is set to 1000, and if the value of register m is 1000 or more, the next step is
Proceed to 142. As a result of the above, when the current engine speed N and load Q/N are values on the learning map, those values are stored in registers m and n, respectively, and the current engine speed N and load Q/N are on the learning map. When the upper and lower limit values are exceeded, the upper and lower limit values are stored in registers m and n, respectively. Steps 142 to 149 are a routine for selecting four points on the learning map. first,
In step 142, the value obtained by subtracting the load value 0.6 [/rev.] at address 0 from the value of register n is stored in register n. Next, in step 143, the load scale interval of the register value is 0.2[/
rev.], the integer part of the quotient is stored in register n, and the remainder of the quotient is stored in register y. The value of this register y is the load value y from address n in Figure 2 to the point indicating the current engine condition.
be equivalent to. In addition, the integer part of the quotient stored in register n is the column of addresses closest to the point indicating the current engine condition and below the point indicating the current engine condition (horizontal array of addresses, for example, addresses 0 to 5). The first column is the first column). and,
In step 144, the value of register y is further increased by 0.2.
Divide by [/rev.]. Therefore, the value corresponding to y/Y in the above-mentioned equation (6) is finally stored in register y. In step 145, the engine speed value at address 0, 1000 [r.
pm] is subtracted and stored in register m.
Next, in step 146, the value in the register m is divided by the engine speed scale interval [rpm], and the integer part of the quotient is stored in the register m, and the remainder of the quotient is stored in the register x. The value of this register x is the value x of the engine speed from address n in Figure 2 to the point indicating the current engine condition.
be equivalent to. In addition, the integer part of the quotient stored in register m is the row of addresses closest to the point indicating the current engine condition and below the point indicating the current engine condition (vertical arrangement of addresses, for example 0, 6, The first row is the sequence of addresses 12 and 18).
Then, in step 147, the value of register x is further divided by 1000 [rpm]. Therefore, the value corresponding to x/X in the above-mentioned equations (4) and (5) is finally stored in the register x. Next, in step 148, the value of register n is multiplied by 6, stored in register n, and the next step is started.
At 149, the value of register n and the value of register m are added and stored in register n. As a result,
The address of the lower left corner of the four points surrounding the current engine condition,
In other words, the address number of address n in FIG. 2 is obtained,
Stored in register n. In step 150, the learning retardation amount θ _KGo stored at address n on the learning map is read out and stored in register A, and the learning retardation amount θ _KG(o+1) stored at address n+1 is read out. The learned retard amount θ KG(o+6) stored at address n+6 is read out and stored in register B, and the learned retard amount θ _{KG (o+6)} stored at address n+7 is read and stored in register C. _o+7) and stores it in register D. Subsequently, in step 151, the value of register B is subtracted from the value of register A, the value of register x is multiplied, and the value of register A is added to this value, and the result is stored in register E. Further, in step 152, the value of register D is subtracted from the value of register C, the value of register x is multiplied, and the value of register C is added to this value, and the value is stored in register F. Finally, in step 153, the value of register F is subtracted from the value of register E, multiplied by the value of register y, and the value of register E is added to that value to learn a point indicating the current engine condition. Let the amount of retardation be θ _KG . Next, a learning control routine in another embodiment of the present invention will be explained using FIG. 14. In addition, the 14th
In the figure, the same parts as in FIG. 12 are given the same reference numerals, and the explanation will be omitted. The difference between the learning control routine of FIG. 12 and the learning control routine of FIG. 14 is that steps 125, 126, and 127 are used in place of step 124 of FIG. 12 in FIG. After the learning retard angle for the current engine condition is calculated in step 115, it is determined in step 125 whether the load Q/N is 0.9 [/rev.] or more. If the load is 0.9 [/rev.] or more, it is determined in step 127 whether the engine rotation speed N is 1200 [rpm] or more, and if the load is less than 0.9 [/rev.], the engine rotation is determined in step 126. The number is 1500 [rpm]
Determine whether the value is less than or equal to the value. If the engine speed is 1200 [rpm] or more in step 127, the process advances to step 116, and the engine speed is 1200 [rpm].
If it is less than 1, proceed to the main routine. Also,
If the engine speed is less than 1500 in step 126, proceed to the main routine and check the engine speed.
If it is 1500 [rpm] or more, proceed to step 127. As a result, Q/N<0.9 [/rev.] and N<
1500 [rpm] area and Q/N≧0.9 [/rev.]
In addition, learning control is not performed in the region where N<1200 [rpm], and learning control is performed in other regions. According to this embodiment, since the learning control region is widened on the high load side where knocking is likely to occur, better learning control can be performed. Conditions for corrected retardation amount θ _{K and learning retardation amount θ KG when} updating learning retardation amount θ _KG by learning control in the learning routines shown in FIGS. 12 and 14 above.
The following table summarizes the relationship with the increase/decrease in

[Table] Furthermore, FIG. 15 shows changes in the corrected retard amount θ _K , learned retard amount θ _KG , and ignition timing θ _ig over time.
As can be understood from the figure, when the corrected retard amount θ _K is within a predetermined range, the learned retard amount θ _KG is constant;
When the corrected retard amount θ _K exceeds a predetermined range, the learned retard amount θ _KG increases, and when the corrected retard amount θ _K is less than a predetermined range, it decreases. Furthermore, FIG. 16 shows variations in ignition timing corresponding to engine speed. In Figure 16, the curve C _1
.about.C3 are the same as those in FIG. 3, and it is understood that the corrected retard amount θ _K is always constant regardless of whether knocking is likely to occur or when knocking is unlikely to occur.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the learning map, Figure 2 is an explanatory diagram showing a point indicating the current engine condition and the four points surrounding this point, and Figure 3 is a line indicating the relationship between engine speed and ignition timing. 4 is a schematic diagram showing an engine to which the present invention is applied, FIG. 5 is a block diagram showing the electronic control circuit of FIG. 4, FIG. 6 is a flowchart of an interrupt routine every 30° CA, and FIG. Figure 8 is a flowchart of time coincidence interrupt A, Figure 8 is a flowchart of time coincidence interrupt B, Figure 9 is a flowchart of the A/D completion interrupt routine, Figure 10 is a flowchart showing the interrupt routine every 4 msec, and Figure 11 is a flowchart of the A/D completion interrupt routine. FIG. 12 is a flowchart of a routine for updating the correction retardation amount; FIG. 12 is a flowchart of a learning control routine; FIG. 13 is a flowchart of a two-dimensional interpolation routine;
Fig. 14 is a flowchart showing a learning routine of another embodiment, Fig. 15 is a line chart showing changes in corrected retardation amount, learning retardation amount, and ignition timing over time, and Fig. 16 is the same as Fig. 3. FIG. 3 is a diagram showing the relationship between the engine rotation speed and the ignition timing, the corrected retard amount, and the learned retard amount. 2... Air flow meter, 12... Fuel injection valve, 18... Notking sensor, 32... Engine rotation angle sensor, 34... Electronic control circuit.

Claims (1)

[Scope of Claims] 1. A correction retard amount that is added or subtracted from the basic ignition advance angle determined by the engine speed and load depending on the presence or absence of knocking, and the engine speed to bring the level of knocking to a predetermined level. Knocking control for an internal combustion engine that controls knocking by subtracting the sum of a learning retardation amount that is determined by the number of motors and the load and that is rewritten when the magnitude of the corrected retardation amount is out of a predetermined range. In the method, the learning control of the learned retardation amount is stopped in an area where the engine rotational speed is less than a predetermined rotational speed on the low rotational side, and the corrected retardation amount is stopped in an area where the engine rotational speed is equal to or higher than the predetermined rotational speed. A knocking control method for an internal combustion engine, characterized in that the learning retardation amount is learning-controlled so as to fall within a predetermined range. 2. Knocking control for an internal combustion engine according to claim 1, wherein the predetermined rotation speed is changed according to the load, and the predetermined rotation speed when the load is below the predetermined load is greater than the predetermined rotation speed when the predetermined load is exceeded. Method.