JPH0646026B2 - Knotting control method for internal combustion engine - Google Patents

Description

The present invention relates to a knocking control method for an internal combustion engine, and particularly to a comparison between a corrected retard amount for performing a retard angle at a relatively high speed depending on the presence or absence of knocking and the presence or absence of knocking. The present invention relates to a method of correcting the basic ignition advance angle and controlling the knocking by performing the retard advance at a relatively slow speed and using the learning retard amount changed by the learning control.

A conventional knocking control method based on learning control uses a ratio Q / of engine speed N, intake air amount Q and engine speed N /
The basic ignition advance angle θ _BASE, which is determined in advance by the load determined by N or the intake pipe negative pressure, is stored in the form of a map in the read-only memory (ROM) of the microcomputer, and is actually calculated based on the following equation (1). The ignition advance angle θ _ig for controlling the igniter is calculated, and the knocking control is performed using this ignition advance angle. Note that the knocking control is not performed because the knocking does not occur under a light load such as during idling.

θ _ig = θ _BASE − (θ _KG + θ _K ) ... (1) However, θ _KG is determined by the engine speed and the load in order to set the knocking level to a predetermined level and is changed by learning control. The learning retard amount, θ _K, is a corrected retard amount that retards the ignition timing when knocking occurs and advances the ignition timing when knocking does not occur.

Here, the correction retardation amount θ _K is obtained as follows, for example. First, the engine vibration is detected by using a knocking sensor composed of a microphone or the like, and a predetermined multiple Kb (where K is a proportional constant) of an average value (back ground) b of the engine vibration and a peak value a of the engine vibration are detected. Seeking
The peak value a and the value of Kb are compared. When the peak value a exceeds the value of Kb, it is determined that knocking has occurred, and as shown in the following equation (2), correction is performed so that the ignition timing is delayed by a predetermined crank angle (for example, 0.4 ° C A) per occurrence of knocking. Change the retard angle θ _K.

θ _K ← θ _K + 0.4 ° C A ... (2) When the peak value a is less than or equal to the value of Kb, it is determined that no knocking has occurred, and the first timer is used for a predetermined time (for example, 48 msec). ) Judging whether or not it has passed,
When the predetermined time has elapsed, the correction retard angle amount θ _K is changed so that a predetermined crank angle (for example, 0.08 ° C. A) ignition timing advances as shown in the following expression (3).

θ _K ← θ _K −0.08 ° C. A (3) Further, the learning retard amount θ _KG according to the engine condition is calculated as follows. First, as shown in FIG. 1, the random access memory (RAM) of the microcomputer is provided with addresses 0 to 23 for storing the learning retard amount corresponding to the engine speed N and the load Q / N, and the learning map is prepared. Is created. By taking in the engine speed N and the intake air amount Q, four RAM addresses surrounding the point (N, Q / N) indicating the current engine condition on the learning map are obtained.
Now, as shown in FIG. 2, the RAM address surrounding the point indicating the current engine condition is n (n = 0.1 ... 16), n +.
1, n + 6, n + 7, the learning retard amount θ _{KGn at} the address n, the learning retard amount θ _KG (n + 1) at the address n + 1, the learning retard amount θ _KG (n + 6) at the address n + 6, and the learning retard angle at the address n + 7. It is assumed that each quantity θ _KG (n + 7) is stored. The difference in engine speed between the addresses is X, the difference in load between the addresses is Y, the difference in engine speed between the address n and the point indicating the current engine condition is x, and the difference between the address n and the current engine is x. If the load difference between the point indicating the condition is y, the learning delay amount θ _{KG at the} point indicating the current engine condition is obtained by the two-dimensional interpolation method shown in the following equations (4) to (6). To be

The learning control of the learning map is performed as follows. First, a second timer that determines the learning control time according to the current engine condition and a third timer that determines the learning control time regardless of the engine condition are prepared. Predetermined time (for example, 48 msec) by the second timer
When it is detected that the time has elapsed, it is determined whether or not the corrected retard angle θ _K has been changed to exceed the predetermined crank angle (for example, 4 ° C. A), and the corrected retard amount θ _K has exceeded the predetermined crank angle. At this time, a predetermined crank angle (for example, 0.04 ° C. A) is added to the learning retard amounts of four points on the learning map surrounding the point indicating the current engine condition described above. As a result, the learning retard amount is learned and controlled so that the ignition timing is delayed. On the other hand, when it is detected by the third timer that a predetermined time (for example, 16 sec) has elapsed, regardless of presence or absence of knocking, a predetermined crank (for example, 0.01 ° C.A) is applied from the learning retard amount of all addresses on the learning map. ) The learning retard angle is learned and controlled by subtracting the ignition timing so that the ignition timing advances.

Thus, the corrected retard angle θ changed as described above
_K and the learning retard angle amount θ _KG obtained by the two-dimensional interpolation method from the learning map to be learning-controlled, the basic ignition advance angle θ _BASE is corrected based on the equation (1) to control the knocking. Of.

By the way, as shown in FIG. 3, the basic ignition advance θ _BASE, that is, MBT (Minimum Spark-Advance For Best Torgu
e) changes like a curve C ₁ according to the engine speed. In addition, the minute knocking occurrence ignition timing when the knocking is difficult to occur, such as when the air is moist, is the curve C.
₂ , the minute knocking occurrence ignition timing when the knocking is likely to occur, such as when the air is dry, becomes like the curve C ₃ . Therefore, the minute knocking occurrence ignition timing differs depending on the engine speed and the environmental conditions.

Therefore, in the notking control method by the learning control as described above, all the learning retard amounts are independently changed to the advance side by the learning control regardless of the presence or absence of the knocking when the predetermined time has elapsed. Under engine conditions where there are few opportunities for learning control on the angle side, there is a problem that the learning retard amount becomes too advanced and knocking occurs. Further, as described above, the learning retard amount tends to be learned and controlled toward the advance side, so that the learning control speed for controlling the ignition timing toward the advance side cannot be set fast, and the above-mentioned FIG. When the engine conditions and other factors change to make it difficult for knocking to occur, the ignition timing may be retarded too much due to the learning retardation amount, and the plague torque cannot be obtained in the region where knocking does not occur. There was a problem.

Here, in order to solve the above-mentioned problem, it is conceivable that all the learning retardation amounts are learned and controlled so that the correction retardation amount becomes a value within a predetermined range. When the engine condition is in the high load range, the learning control is performed so that the learning delay amount decreases in the region where the value is less than the value. For this reason, there arises a problem that knocking occurs when the load slightly increases from a region where the corrected retard amount is equal to or less than the predetermined value.

The present invention has been made to solve the above problems, and the learning retard angle is not disturbed even when the engine is operated in the light load range, and no knocking occurs even if the load is slightly increased from the light load range. It is an object of the present invention to provide a knotting control method of the above.

In order to achieve the above object, the structure of the present invention distinguishes between a knocking control region and a knocking non-control region, and in the knocking control region, from the basic ignition advance angle determined by the engine speed and the load, knocking is When the ignition timing is generated, the ignition timing is retarded, and when the knocking is not generated, the ignition timing is advanced, and the amount of the corrected ignition retard amount provided to set the knocking level to a predetermined level is the first. When the ignition timing is calculated by subtracting the sum with the learning retard amount rewritten by the learning control when it is equal to or more than the predetermined value of 1 or less than the second predetermined value, Therefore, the learning control of the learning retard amount under a predetermined load or less on the light load side adjacent to the non-knocking control region may be stopped. It is.

According to the above configuration of the present invention, since the learning control is stopped in the specific region on the light load side, the learning retard amount on the high load side is not destroyed even when the engine condition exists in the specific region. The unique effect that the optimal knocking control can be maintained and the occurrence of knocking when the load rises from a light load can be reduced is obtained.

Next, an example of an engine to which the present invention is applied is shown in FIG. As shown in the drawing, this engine includes an air flow meter 2 as an intake air amount sensor provided on the downstream side of an air cleaner (not shown). The air flow meter 2 is composed of a compensation plate 2A that is rotatably provided in the dipping chamber, and a potentiometer 2B that detects the opening of the compensation plate 2A. Therefore, the intake air amount Q is detected as the voltage output from the potentiometer 2B. An intake air temperature sensor 4 for detecting the temperature of intake air is provided near the air flow meter 2.

A throttle valve 6 is arranged downstream of the air flow meter 2, and a surge tank 8 is provided downstream of the throttle valve 6.
Is provided. An intake manifold 10 is connected to the surge tank 8, and a fuel injection valve 12 is arranged so as to project into the intake manifold 10. The intake manifold 10 is connected to the combustion chamber 14A of the engine body 14 and is connected to the combustion chamber 1 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 main body 14 is provided with a knocking sensor 18 configured by a microphone or the like for detecting engine vibration. 20 is a spark plug, 22
Is an O ₂ sensor for controlling the air-fuel mixture near the stoichiometric air-fuel ratio, and 24 is a cold / hot water temperature sensor for detecting 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. This Distributor 2
6 is provided with a cylinder discrimination sensor 30 and an engine rotation angle sensor 32 which are composed of a pick-up and a signal rotor fixed to the distributor. The cylinder discrimination sensor 30 has, for example, a crank angle of 7
A cylinder discrimination signal is output every 20 degrees to an electronic control circuit 34 composed of a microcomputer, and the engine rotation angle sensor 32 outputs a crank angle reference position signal to the electronic control circuit 34, for example, every 30 degrees of the crank angle. To do.

The electronic control circuit 34, as shown in FIG.
Access memory (RAM) 36, read only memory (ROM) 38, and central processing unit (CPU) 4
0, a clock (CLOCK) 41, a first input / output port 42, a second input / output port 44, a first output port 46, and a second output port 48, and the RAM 36. , ROM38, CPU40, CLOCK
41, first input / output port 42, second input / output port 4
4, first output port 46 and second output port 48
Are connected by a bus 50. The first input / output port 42 has a buffer (not shown), a multiplexer 5
4, an air flow meter 2, a cooling water temperature sensor 24, an intake air temperature sensor 4 and the like are connected via an analog-digital (A / D) converter 56. The multiplexer 54 and the A / D converter 56 are connected to the first input / output port 4
It is controlled by the signal output from 2. 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 the engine rotation angle sensor 32 are connected via a waveform shaping circuit 64. ing. The second input / output port 44 is also connected to the knocking sensor 18 via a band pass filter 60, a peak hold circuit 61, 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 and a second output for inputting either one of the output of the peak hold circuit 61 and the output of the integrating circuit 63 to an A / D converter 68. The control signal output from the input / output port 44 is input, and the 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 a drive circuit 70, and the second output port 48 is connected to the fuel injection valve device 12 via a drive circuit 72.

In the ROM 38 of the electronic control circuit 34, the map of the basic ignition advance angle θ _BASE represented by the engine speed and the intake air amount, the basic fuel injection amount, and the like are stored in advance. The signal from the air flow meter 2 and the engine speed are stored. Corner sensor 3
The basic ignition advance angle and the basic fuel injection amount are read by the signal from 2 and various signals including the signals from the cooling water temperature sensor 24 and the intake air temperature sensor 4 are used to determine the basic ignition advance angle and the basic fuel injection amount. The corrected ignition advance and the corrected fuel injection amount are added, 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 that controls the air-fuel ratio of the air-fuel mixture to near the stoichiometric air-fuel ratio. In addition, the electronic control circuit 34
The learning map shown in FIG. 1 is stored in advance in the RAM 36.

Next, an embodiment in which the present invention is applied to the above engine will be described in detail. In the description of the embodiment of the present invention, the main routine of fuel injection control, air-fuel ratio control, ignition timing control, etc. is the same as the conventional one, and therefore the description thereof is omitted and the knocking control related to the present invention is omitted. Only the routine will be described.

FIG. 6 shows an interrupt routine for every 30 ° C. A when the present invention is carried out by using a microcomputer. First,
At step 81, the engine speed N is obtained from the rotation time based on the signal from the engine rotation angle sensor 32. At step 82, the number of interrupts after the cylinder discrimination signal is input from the cylinder discrimination sensor 30 is counted and the current interrupt is counted. Set a flag that indicates the crank angle. Next, at step 83, the flag set at step 82 is set to the top dead center (TD
It is determined whether the flag is C). When it is not the top dead center at present, the routine proceeds to step 88, and when it is now the top dead center, it is judged at step 84 whether or not the knock gate is closed. When the knock gate is open, the knock gate is closed at step 85, and when the knock gate is closed, the channel switching circuit 66 is switched at step 86, and the engine vibration signal output from the knocking sensor 18 is integrated by the band pass filter 60 and integrated. A / D via circuit 63 and channel switching circuit 66
It is input to the converter 68, and the average value of the engine vibration, that is, the A / D conversion of the background level is started. Then, at step 87, the closing time t ₁ of the knock gate,
That is, next, the time at which the knock gate is closed is calculated, and the time coincidence interrupt A is set.

Next, in step 88, the crank angle is 90 ° C. A BTDC (before top dead center) based on the flag set in step 82.
Judging whether or not Crank angle is 90 ° C AB
If not TDC, proceed to step 91, 90 ° C AB
In the case of TDC, in step 89, the corrected advance amount θ _K is updated and the ignition timing calculation process is performed (the details will be described below). At step 90, the time at which the igniter 28 is turned on is obtained from the ignition timing calculated at step 89 and the current time, and the time coincidence interrupt B is obtained.
And set the igniter on flag. Then, in step 91, the crank angle is 60 ° C.
A BTDC is judged whether or not, 60 ℃ A BT
If it is not DC, it returns to the main routine and 60
If it is .degree. C. A BTDC, the igniter OFF time is calculated in step 92, the time coincidence interrupt B is set, and the igniter ON flag set in step 90 is cleared.

Next, the time coincidence interrupt A shown in FIG. 7 will be described.
This interrupt routine is for obtaining the peak value of the engine vibration, and is interrupted at the time set in step 87 of FIG. 6, and the peak value held in the peak hold circuit 61 in step 93 is changed to the channel switching circuit. The peak hold value is input to the A / D converter 68 via 66 to start the A / D conversion of the peak hold value, and the process returns to the main routine.

FIG. 8 shows a routine of the time coincidence interrupt B. When the time set in step 90 and step 92 in FIG. In step 94, it is judged whether the igniter on flag is set, that is, whether this flag is 1 or not. When the flag is set, the igniter is turned on in step 96, and when the flag is set, the igniter is set in step 95. Turn on and return to the main routine.

FIG. 9 shows an A / D conversion completion interrupt routine, which is executed when the background level A / D conversion and the peak hold value A / D conversion are completed. First, in step 97, it is determined whether or not the knock gate is currently open. When the nork gate is closed, the A / D converted value converted in step 86 of FIG. 6 is stored in the memory of the RAM 36 in step 98 to set it as the back ground level b, and in step 99 the notch gate is opened to return to the main routine. To do. On the other hand, when the knock gate is open, the A / D conversion value converted in step 93 of FIG.
The peak value a is stored in the memory of the AM 36, the knock gate is closed in step 101, and the process returns to the main routine.

FIG. 10 shows an interrupt routine that is performed every predetermined time (for example, 4 msec) for counting the time when no knocking occurs and the time for learning control. First, in step 102, the count value of the counter TIME1 for obtaining the time when the knocking does not occur is incremented by 1, and in step 103, the count value of the counter TIME2 for obtaining the time for learning control is set to 1
increase. At the next step 104, the counter T
It is determined whether the count value of IME1 is 12 (48 msec) or less. When the count value exceeds 12, in step 105, the counter TIME1
Is set to 12, and when the count value is 12 or less, it is determined in step 106 whether the count value of the counter TIME2 is 12 or less. Here, when the count value exceeds 12, step 1
In 07, when the count value of the counter TIME2 is 12 or less, the process returns to the main routine.

Next, the detailed routine of step 89 in FIG. 6 will be described with reference to FIG. When it is determined in step 88 of FIG. 6 that the crank angle has reached 90 ° C. BTDC, it is determined in step 122 whether the load Q / N is 0.6 [/ rev] or more, that is, whether it is in the knocking control region. to decide. When it is not in the knocking control region, the basic ignition advance angle θ _{BASE is set} to the ignition advance angle θig in step 123, and when it is in the knocking control region, step is performed. At 108, the peak value a stored at step 100 in FIG. 9 is compared with the background value b stored at step 98 in FIG. 9 multiplied by a constant K, Kb. The peak value a is the value K
When b is exceeded, it is determined that knocking has occurred, the correction retard angle amount θ _K is increased by a predetermined angle (for example, 0.4 ° CA) in step 110, and a counter for counting the time when no knocking occurs in step 112. Clear the count value of TIME1. On the other hand, when the peak value a is less than or equal to the value Kb, it is determined that the knocking does not occur, and it is determined in step 109 whether or not the count value of the counter TIME1 is equal to or more than the predetermined value (12), and the count value is the predetermined value. When the above is the case, the state in which no knocking occurs continues for a predetermined time. Therefore, in step 111, the correction retard angle amount θ _K is decreased by a predetermined angle (for example, 0.08 ° A), and then step 112 is performed.
The counter TIME1 is cleared with. Also, step 1
In 09, when the count value is less than the predetermined value,
Proceed to step 113. In step 113, 2 is obtained from the corrected advance / retard amount θ _K obtained as described above and the learning map.
The basic ignition advance angle θ _BASE is corrected by the learning retard amount θ _KG obtained by the three-dimensional interpolation method as shown in the equation (1) described above, and the ignition advance angle θig for actually controlling the igniter is calculated.

Next, a routine for obtaining the learning advance amount θ _KG corresponding to the current engine condition from the learning map and performing learning control will be described. FIG. 12 shows this routine from the middle of the main routine. In addition, the learning map shown in FIG. 1, 6, 7, 8,
Learning control is not performed for addresses 14, 15, 16, and 17.

First, in step 124, the load Q / N is 0.6 [
/ Rev] or more, that is, whether it is in the knocking control region or not. If it is in the knocking control region, the main routine is continued as it is, and if it is in the knocking control region, in step 114, a point indicating the current engine condition determined by the engine speed N and the load Q / N is surrounded 4
Find the RAM address of the point on the learning map. Next, in step 115, the two-dimensional interpolation method (two-dimensional interpolation method) is performed on the basis of the data stored in the obtained four-point RAM addresses, that is, the learning delay amount stored in the four-point RAM addresses. The routine will be described later), and the learning advance amount θ _KG of the point indicating the current engine condition is calculated, and the calculated value is R
Store in a predetermined location in AM.

At the next step 125, the engine speed H is 3000.
It is judged whether it is less than [rpm] and the engine speed is 3
If it is less than 000 [rpm], it is judged in step 126 whether the load Q / N is more than 0.8 [/ rev]. If the engine speed exceeds 3000 [rpm], in step 127. Load Q / N is 1.0 [/ r
[ev]] or less. When the load is 0.8 [/ rev] or more in step 126, the next step 116
If the load is less than 0.8 [/ rev], proceed to the next routine. If the load is 1.0 [/ rev] or more in step 127, the next step 116
If the load is less than 1.0, proceed to the next routine. As a result, the learning map shown in FIG.
When there is a point indicating the engine condition in a specific area below the line connecting the addresses 8, 14, 15, 16, 17, the learning control is not performed and the engine condition is shown in the area excluding this specific area. Only when there is a point, the learning control shown in step 116 to step 121 is performed.

At step 116, a counter TI for obtaining the learning control time counted at step 103 in FIG.
It is determined whether the count value of ME2 is equal to or greater than a predetermined value (for example, 12). 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 the counter TIME2 is cleared in step 117 and then updated in steps 110 and 111 in FIG. Step 11 is performed to determine whether the corrected retard angle amount θ _K is equal to or larger than the first predetermined crank angle (for example, 2 ° A).
Judge with 8.

If it is determined in step 118 that the corrected retard amount θ _K is less than the first predetermined crank angle, in step 121 it is stored at four points on the learning map surrounding the point indicating the current engine condition. Learning control for subtracting a predetermined crank angle (for example, 0.04 CA) from each of the learning retard amounts is performed, and the process returns to the main routine. As a result, when the corrected advance amount θ _K is less than the first predetermined crank angle, the learning control is performed so that the learning delay amount of the learning map becomes small, and the ignition timing is advanced according to the learning retard amount. To be done. On the other hand, if it is determined in step 118 that the corrected retard amount θ _K is greater than or equal to the first predetermined crank angle, in step 119, the corrected retard amount θ _K is set to a value larger than the first predetermined crank angle. 2 predetermined crank angle (eg 4 ° C
It is determined whether or not less than A). When it is determined in step 119 that the corrected retard amount θ _K is less than the first predetermined crank angle, that is, when the corrected retard amount θ _K satisfies the following condition, the first predetermined crank angle ( 2 ° C) ≤ θ _K <second predetermined crank angle (4 ° A) ...
(7) Return to the main routine without learning control. As a result, the learning control is not performed when the corrected retard amount θ _K takes a value in the predetermined range, and the ignition timing is not changed depending on the learned retard amount. It should be noted that learning control may be performed as necessary even when the correction delay amount takes a value within a predetermined range. If it is determined in step 119 that the corrected retard amount θ _K is greater than or equal to the second predetermined crank angle, in step 120, the learning delays stored at the four points on the learning map surrounding the point indicating the current engine condition are stored. Learning control for adding a predetermined crank (for example, 0.04 ° C. A) to each angular amount is performed, and a return is made to the main routine. As a result, the learning control is performed so that the learning delay amount of the learning map becomes large when the corrected retard amount θ _K is equal to or greater than the second predetermined crank angle, and the ignition timing is delayed by the learning retard amount. To be done.

By performing the learning control as described above, the learning delay amount of the learning map is changed so that the correction delay amount becomes a value within a predetermined range.

The learning routine shown in FIG. 12 will be described in detail below.

FIG. 13 shows a detailed routine of the two-dimensional interpolation method in step 115 of FIG. In this two-dimensional interpolation routine, the map shown in FIG. 1 is used as a learning map, and the four RAM addresses indicating the current engine conditions are set to n, n + 1, m + 6, n + 7 as shown in FIG. . First, in step 130, the present load Q /
N is the upper limit of the load on the learning map, that is, 1.2 [/
rev] or less. The load is 1.2
If [/ rev] is exceeded, 1.2 is stored in the register n in step 131 and the load is 1.2 [/ rev].
v] or less, the current load Q at step 134
Store the value of / N in register n. In step 135, it is determined whether or not the current engine speed N is less than or equal to the upper limit value of the engine speed on the learning map, that is, 6000 [rpm]. The engine speed is 6000 [rp
[m] is exceeded, the register m is reached in step 136.
6000 is stored, and the engine speed is 6000 [rp
m] or less, the current value of the engine speed N is stored in the register m in step 137. Step 13
In step 8, it is judged whether or not the value of the register n is equal to or more than the lower limit value of the load on the learning map, that is, 0.6 [/ rev] or more. If the value of n is 0.6 and the value of register n is 0.6 or more, the process proceeds to step 140. Then, in step 140, the value of the register m is the lower limit value of the engine speed on the learning map, that is, 1000.
If the value of the register m is less than 1000, the value of the register m is set to 1000 and the value of the register m is set to 10 in step 141.
When it is 00 or more, the routine proceeds to the next step 142. As a result, when the current engine speed N and the load Q / N are values on the learning map, the values are stored in the registers m and n, respectively, and the current engine speed N and the load Q / N are learned by the learning map. When the upper and lower limits are exceeded, the upper and lower limits 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, a value obtained by subtracting the value of the 0th load 0.6 [/ rev] from the value of the register n is stored in the register n. Next, in step 143, the value of the register n is divided by the load scale interval of 0.2 [/ rev], the integer part of the quotient is stored in the register n, and the remainder of the quotient is stored in the register y. The value of this register y is equal to the value y of the load from address n in FIG. 2 to the point indicating the current engine condition. In addition, the integer part of the quotient stored in the register n is a column of addresses that are closest to the point indicating the current engine condition and are equal to or less than the point indicating the current engine condition (horizontal arrangement of addresses, for example, 0-5 addresses). Is the first column). Then, in step 144, the value of the register y is further divided by 0.2 [/ rev]. Therefore, finally, in the register y,
A value corresponding to y / Y in the expression (6) is stored.

In step 145, the value of the engine speed at address 0 is 10000 [rpm] from the value of register m, as described above.
The value obtained by subtracting is stored in the register m. Next, in step 146, the value of the register m is divided by the scale interval 1000 [rpm] of the engine speed, 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 the register x is equal to the value x of the engine speed from the address n in FIG. 2 to the point indicating the current engine condition. In addition, the integer part of the quotient stored in the register m is the row of the addresses that are closest to the point indicating the current engine condition and are equal to or less than the point indicating the current engine condition (a vertical array of addresses, for example, 0, 6, The row number of addresses 12 and 18 is the first row). Then, in step 147, the value of the register x is further increased to 1000 [rp
m]. Therefore, finally, the register x stores the value corresponding to x / X in the equations (4) and (5).

Next, in step 148, the value of the register n is multiplied by 6 and stored in the register n, and in the next step 149, the value of the register n and the value of the register m are added and stored in the register n. As a result, the four lower left corner addresses surrounding the current engine condition, that is, the address number of the nth address in FIG. 2 are obtained and stored in the register n.

In step 150, the learning delay amount θ _KGn stored at address n on the learning _map is read out and stored in register A, and the learning delay amount θ _KG stored at address n + 1.
(N + 1) is read out and stored in the register B, the learning retardation amount θ _KG (n + 6) stored at address n + 6 is stored in the register C, and the learning retardation amount θ stored at address n + 7. _{Read KG} (n + 7) and register D
To memorize. Then, in step (5), the value of register B is subtracted from the value of register A and the value of register x is multiplied, and the value of register A is added to the value and stored in register E. 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 the value and stored in register F. Finally, at step 153, the value of the register E is subtracted from the value of the register E, the value of the register y is multiplied, and the value of the register E is added to the value to learn the point indicating the current engine condition. The amount of retardation is θ _KG .

The learning retard amount θ _KG in the learning routine shown in FIG.
The following table summarizes the relationship between the condition of the corrected retard amount θ _K and the increase / decrease of the learned retard amount θ _KG when updating is performed by learning control.

Further, FIG. 14 shows changes in the corrected retard amount θ _K , the learned retard amount θ _KG , and the ignition timing θ _{ig over} time. As can be seen, the retard amount theta _KG learning when the correction retard amount theta _K value of the predetermined range is constant, the retard amount learning when the delay correction amount theta _K exceeds the predetermined range theta _KG increases, and decreases when the corrected retard angle θ _K is less than the predetermined range.

Further, FIG. 15 shows the variation of the ignition timing corresponding to the engine speed. Curves C _{1 to} C ₃ in FIG. 15 are the same as those in FIG. 3, and the correction retard angle amount θ _K is always constant regardless of whether knocking is likely to occur or not. To be understood.

After the above learning control routine is executed, a routine shown in FIG. 16 for executing a constant learning delay amount at a specific address on the light load side is executed. This routine is a continuation of the learning control routine shown in FIG. 12, and is a continuation of the main routine after the completion of this routine. In step 190, addresses of a specific RAM below a predetermined load on the light load side on the learning map shown in FIG. 1 (in this embodiment, addresses 0, 1, 2, 3 existing in the range shown by the hatched lines in FIG. 1) , 4,
5, 9, 10, and 11), the learning retard amount stored in the memory is rewritten to a predetermined crank amount (for example, 0 ° C. A).

By setting the specific learning retardation amount on the light load side to a constant value as described above, the required retardation amount (θ _K + θ _KG ) from the basic ignition advance for the load Q / N is the characteristic shown in FIG. Becomes FIG. 17 shows that the engine speed is 2000 [rpm],
Although it shows a characteristic of 4000 [rpm], on the light load side, the ignition timing at which knocking occurs is on the advance side of the basic ignition advance angle and the learning retard amount is a constant value of 0 ° C. It is understood that the required retardation amount is 0 ° C. A, and the retardation amount rises smoothly.

Further, FIG. 18 shows the relationship between the load and the retard angle amount. As shown in the figure, it is understood that the learning retard amount is substantially constant in the light load region where the load is 0.8 [/ rev] or less.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a learning map, FIG. 2 is an explanatory diagram showing a point indicating a current engine condition and four points surrounding this point, and FIG. 3 is a line showing a relationship between an engine speed and an ignition timing. Figure,
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 flow chart of an interrupt routine every 30 ° C., and FIG. 8 is a flow chart of the time coincidence interrupt B, FIG. 9 is a flow chart of the A / D completion interruption routine, FIG. 10 is a flow chart showing an interruption routine of every 4 msec, and FIG. 11 is a correction delay. Flow chart of the routine for updating the angular amount, first
FIG. 2 is a flow chart of a learning control routine, FIG. 13 is a flow chart of a two-dimensional interpolation routine, and FIG. 14 is a diagram showing changes in the correction retard amount, the learning retard amount, and the ignition timing with respect to the passage of time.
FIG. 5 is a diagram similar to FIG. 3 showing the relationship between the engine speed and the ignition timing, the relationship between the correction retard amount and the learning retard amount;
FIG. 6 is a flow chart showing a routine for setting a specific learning retard amount to a constant value, FIG. 17 is a diagram showing a required advance angle characteristic with respect to a load, and FIG. 18 is a line showing an ignition timing characteristic with respect to a load. It is a figure. 2 ... Air flow meter, 12 ... Fuel injection valve, 18 ... Notting sensor, 32 ... Engine rotation angle sensor, 34 ... Electronic control circuit.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshio Suematsu 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Corporation (56) Reference JP-A-57-105530 (JP, A)

Claims (1)

[Claims] 1. A knocking control region and a knocking non-controlling region are distinguished from each other, and in the knocking control region, the ignition timing is delayed and knocking occurs when knocking occurs from a basic ignition advance angle determined by an engine speed and a load. When the ignition timing is not generated, the correction delay amount set to advance the ignition timing and the correction delay amount provided for setting the knocking level to a predetermined level are equal to or larger than a first predetermined value or a second predetermined value. In a knocking control method for an internal combustion engine that calculates an ignition timing by subtracting the sum of a learning retardation amount rewritten by learning control when the value is less than or equal to a value, in a lightning control adjacent to the non-knocking control region in the knocking control region. Knocking control of an internal combustion engine, characterized in that learning control of the learning retard amount is stopped under a predetermined load on the load side Law.