JPS59113264A - Controlling methd of knocking in internal-combustion engine - Google Patents

Abstract

PURPOSE:To permit proper learning control under all engine conditions by a method wherein a program is shortened and the learning value of an address near the present engine condition is increased while the same of the address far from the present engine condition is decreased. CONSTITUTION:A value alpha'' is obtained by multiplying the learned value by (x) in a step 170 and the learned value alpha is obtained by substracting the value alpha'' from the learned value alpha in the step 171. The value alpha, obtained in the step 171 is multiplied by (y) in the step 172 and the result is memorized once into a register alpha'. The value of the register alpha' is represented by alpha(1-x)y when it is represented by employing the learned value alpha. According to this method, the amount of the learned value at the address near a point showing the present engine condition is increased and the amount of the learned value at the address far from the point showing the present engine condition is reduced to effect the learning control while the delayed amount of a corrected spark angle may be brought into the value within a predetermined range in accordance with the delaying amount of the corrected spark angle.

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 correction retardation amount for retarding at a relatively fast speed depending on the presence or absence of knocking, and a correction retardation amount for performing a retardation at a relatively fast speed depending on the presence or absence of knocking. The present invention relates to an improvement of learning control in a method of controlling knocking by correcting the basic ignition advance angle by retarding the ignition angle and changing the learning retardation amount by learning control.

In the conventional knocking control method using learning control, the ratio of the engine rotation speed N1 to the intake air amount Q and the engine rotation speed N is Q/
The basic ignition advance angle θaAsxk, which is predetermined by the load determined by the N or intake pipe negative pressure, is stored in the read-only memory (ROM) of the microcomputer in the form of a map, and the igniter is actually controlled based on the following equation (1). The ignition advance angle θI is calculated, and the knocking control is performed using this ignition advance angle.

θiy=θBABK (θKG+θK)・・・・・・
・Song...(1) However, θKG is the knocking level k
Wi is the learned retard amount that is determined by the engine speed and load and changed by learning control in order to maintain a constant level; θ is the amount that delays the ignition timing when knocking occurs and changes the ignition timing when knocking no longer occurs. This is the amount of correction retardation to be advanced.

Here, the corrected retard amount θ is determined as follows.

First, engine vibration is detected using a knocking sensor composed of a microphone, etc., and a predetermined times the average value (background) b of engine vibration, A (where K is a proportionality constant) and a peak value a of engine vibration. This peak value α is compared with the value of K·b. Peak value α φb
When the value exceeds the value, it is determined that knocking has occurred, and the correction retard amount is set so that the ignition timing is delayed by a predetermined crank angle (for example, 0.4° CA) for each occurrence of knocking, as shown in the following equation (2). Change θK.

To θ←θx+0.4°CA ・・・・・・・・・・・・
・・・・・・・・・・・・ (2) Also, the peak value α is −6
If the value is less than or equal to , it is determined that knocking has not occurred, and the first timer is used for a predetermined period of time (for example, 48-
) has elapsed, and when a predetermined time has elapsed, the crank angle is changed to a predetermined crank angle (for example, 0.
08°CA) Change the corrected retard amount θK so that the ignition timing advances.

To θ←θK -0,08°CA ・・・・・・・・・
Song... (3) Further, the learning retardation amount θKG according to the engine conditions is calculated as follows. First, as shown in Fig. 1, addresses O 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 the microcomputer, and a learning map is created. Create. 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 determined.

Now, as shown in Figure 2, the RAM addresses surrounding the current point indicating the engine exclusion are n (n = Q, l, ・16), LE+1, LE+6, LE+7, and the address is learned. Retard amount θK
GFL % Assume that the learned retard amount θKG (rL+6) is stored at address 1+1, the learned retard amount θKG (rL+6) is stored at address 1+6, and the learned retard amount θKG (rL+7) is stored at address 1+7. . Then, the difference in engine speed between addresses is X1, the difference in load between addresses is Y1, and the difference in engine speed between address X1 and a point indicating the current engine condition is expressed as x1, which indicates the current engine condition. The difference in load between the points is y
Then, the current engine &f'? The learning retard amount θKG of the point indicating - is determined.

(5) 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 tQ are prepared. A second timer is used for a predetermined period of time (for example, 48m5ec).
), when it is detected that the correction retard amount θK
is changed and exceeds a predetermined crank angle (for example, 4° CA), and when the corrected retardation amount θK exceeds the predetermined crank angle, the point indicating the current engine condition explained above is determined. Learning control is performed to add a predetermined learning value (for example, 0.04° CA) to four points on the surrounding learning map.

On the other hand, when the third timer detects that a predetermined period of time (for example, 16 formulas) has elapsed, a predetermined learning value (for example, 0. 01CA) Learning control is performed to advance the ignition timing by subtraction.

However, although the learning control described above has the advantage of shortening the program, it is not possible to perform learning control appropriately depending on the engine conditions, resulting in inaccurate knocking control and the occurrence of large knocking. , there was a problem that the engine output decreased.

In order to solve the above problem and perform appropriate learning control under all engine conditions, the distance between the point indicating the current engine condition and the four points surrounding this point is calculated, and weights are assigned according to this distance. Learning control is performed by distributing learning values as shown in the following equation.

However, α is the learned value, “rL z rfL+1, rTL
+6 and rrL+7 are the distances on the learning map between the point indicating the current engine condition and the four addresses surrounding this point.

However, in such learning control, the distance 11111 rnX?
In order to find 7L+1, etc., it is necessary to find the square root of the sum of the square of the engine rotational speed and the square of the load, which causes the problem that the microcomputer program is long and difficult to incorporate into computer control.

In addition, this problem requires a long calculation time, and it is necessary to reduce the frequency of knocking control when the engine speed is high. This causes problems such as frequent knocking at high engine speeds) and a drop in output due to too much retardation of the ignition timing.

The present invention has been made to solve the above problems, and in addition to shortening the program, it increases the learned values at addresses close to the current engine conditions and decreases the learned values at addresses far from the current engine conditions. An object of the present invention is to provide a knocking control method for an internal combustion engine that allows appropriate learning control to be performed under engine conditions.

In order to achieve the above object, the configuration of the present invention is such that the address is changed by learning control to a predetermined address corresponding to engine operating conditions expressed by engine speed and load, and learning is performed to bring the knocking level to a predetermined level. The learning control is performed by storing the retardation amount and adding or subtracting a predetermined value (learning value) to the learning retardation amount at a specific address surrounding the current engine operating condition, and the learning control is performed based on the learning retardation amount at the specific address. The learning retard amount corresponding to the current engine operating conditions is determined, and the ignition timing is retarded and advanced from the basic ignition advance angle determined according to the engine operating conditions according to the learned learning retard amount and knocking. In a knocking control method for an internal combustion engine in which knocking is controlled by subtracting a sum of a corrected retardation amount to The predetermined value is distributed at the ratio of the difference between the specific addresses, and the distributed predetermined value is further divided at the ratio of the difference between the current load and the load at the specific address with respect to the difference in the load between the specific addresses.
, the amount of learning for specific addresses close to the current engine operating conditions is large, and the amount of learning for specific addresses far from the current engine operating conditions is small. As a result, the program is shorter, so it can be incorporated into the limited program of the microcomputer, and the calculation time is shorter, so learning control can be performed in the same way at high engine speeds and low engine speeds, and knocking can be prevented. A particular benefit is improved control.

Further, in the above configuration of the present invention, the predetermined value in the outer region of the knocking control region that includes the upper and lower limits of the engine speed and the upper and lower limits of the load corresponding to the stored learning retard amount is set. It is preferable to make it smaller than a predetermined value inside the knocking control area. By doing this, the accuracy of learning control in the boundary of the learning map and the knocking control area outside the learning map is improved, and opportunities for learning control are increased, making it unnecessary to change the learning map due to changes in engine conditions. We can respond promptly.

By the way, the basic ignition advance angle θBABg, that is, MBT (M
inimum 5park Advance for
13est 'l'orque) changes as shown in curve C1 according to the engine speed, as shown in Fig. 3, and the ignition that causes minute knocking when knocking is difficult to occur, such as when the air is humid. The timing is as shown in curve C7, and when knocking is likely to occur, such as when the air is dry, the ignition timing at which slight knocking occurs is curve C3.
become that way. Therefore, regardless of the conditions where knocking is likely to occur or the conditions where knocking is unlikely to occur, the
In the above configuration of the present invention, the corrected ignition advance angle is within a predetermined range (for example, 2° CA≦θ and ≦4°
It is preferable to perform learning control on the learning retardation amount so that the learning delay angle becomes CA).

Next, FIG. 4 shows an example of an engine to which the present invention is applied. This engine has an air cleaner (
(not shown) is provided with an air meter 2 as an intake air amount sensor. The air flow meter 2 includes a compensation plate (2A) which is rotatably provided in the damping chamber, and a potentiometer (2) that detects the opening degree of the compensation plate (2A) rotatably provided in the damping chamber.
It is composed of B. 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 a surge tank 8 is arranged downstream of the throttle valve 6.
is provided. An intake manifold 1o 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 connected to a combustion chamber 14A of the engine body 14, and the combustion chamber 14A of the engine 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 and configured to detect vibrations of the engine.

Note that 20 is a spark plug, 22 is an 02 sensor for controlling the air-fuel mixture to near the stoichiometric air-fuel ratio, and 24 is a cooling water temperature sensor for detecting the engine cooling water temperature.

The ignition grag 20 of the engine body 140 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 pickup and a signal rotor fixed to a distributor shaft.

This cylinder discrimination sensor 30 outputs a cylinder discrimination signal to an electronic control circuit 34 constituted by a microcomputer or the like, for example, every 720 degrees of crank angle, and this engine rotation angle sensor 32 outputs a cylinder discrimination signal, for example, every 30 degrees of crank angle. A reference position signal is output to the electronic control circuit 34.

The electronic control circuit 34, as shown in FIG.
Access memory (RAM) 36, read only memory (ROM) 38, and central processing unit (CPU)
) 40, a clock (CLOCK) 41, a first input/output port 42, a second output port 44, a first output port 46, and a second output port 48, RAM36, ROM38, CPU40, CLOC
K41, first input/output port 42, second input/output port 44, first output port 46, and second output port 4
8 is connected to bus soK and J:D. The first input/output port 42 includes a buffer (not shown), a multiplexer 54, and an analog-to-digital (A/D) converter 56.
An air flow meter 2, a cooling water temperature sensor 24, and four intake air temperature sensors are connected through the air flow meter 2. The multiplexer 54 and A/D converter 56 are controlled by a signal output from the first input/output port 42. The Ot sensor 22 is connected to the second input/output boat 44 via a buffer (not shown) and a comparator 62, and a cylinder discrimination sensor 30 and an engine rotation angle sensor 32 are connected via a waveform shaping circuit 64. There is.

The second input/output boat 44 also has a pass filter 0. Peak hold circuit 61. Knocking sensor 18 is connected via channel switching circuit 66 and A/D converter 68t. 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 the second input/output port 44 is input to the peak hold circuit 61.
A reset signal is input from

Further, the first output boat 46 is connected to the igniter 28 via the drive circuit 7o, and the second output boat 48 is connected to the fuel injection #t$12 via the drive circuit 72.

The ROM 38 of the electronic control circuit 34 stores the basic ignition advance angle θBASI! expressed by the engine speed and intake air amount. The map and basic fuel injection amount etc. are stored in advance.
The basic ignition advance angle and basic fuel injection amount are read from the signals from the air flow meter 2 and the engine rotation angle sensor 32, and various signals including the signals from the cooling water temperature sensor 24 and the intake air temperature sensor 4 are used to read out the basic ignition advance angle and basic fuel injection amount. , a corrected ignition advance angle and a corrected fuel injection amount are added to the basic ignition advance angle and basic fuel injection amount, and the igniter 28 and the fuel injection valve 12 are controlled. The air-fuel ratio signal output from the 02 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 present invention in detail, the main routines of fuel injection control, air-fuel ratio control, ignition timing control, etc. are the same as conventional ones, so the explanation will be omitted, and only the knocking control routine related to the present invention will be explained. explain.

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 determined from the rotation time based on the signal from the engine rotation angle sensor 32,
In step 82, the number of interruptions after the cylinder discrimination signal is input from the cylinder discrimination sensor 30 is counted, and a flag indicating the current crank angle is set. Next, step 83
, the flag set in step 82 is at top dead center (TD
It is determined whether the flag is C). If the current position is not the top dead center, the process proceeds to step 88, and if the current position is the top dead center, it is determined in step 84 whether or not the knock gate is closed. When the knock gate is open, the knock gate is closed in step 85, and when the knock gate is closed, the channel switching circuit 66 is switched in step 86, and the engine vibration signal output from the knock sensor 18 is passed through the band pass filter 60. , A/D via the integrating circuit 63 and channel switching circuit 66
The signal is input to converter 68 to begin A/D conversion of the average value of engine vibration, ie, background level. Subsequently, in step 87, the knock gate closing side t1, that is, the next time to close the knock gate, is calculated and a time coincidence interrupt A is set.

Next, in step 88, it is determined based on the flag set in step 82 whether the crank angle has reached 90° CA BTDC (before top dead center). Crank angle is 90°C
A If it is not BTDC, proceed to step 91,
In the case of °CA BTDC, the corrected retard amount θ is updated in step 89, and ignition timing calculation processing is performed (details of this will be explained below). Step 9
0, 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, it is determined whether the crank angle has reached 60° CA BTDC,
If it is not 60° CA BTDC, return to the main routine; if it is 60° CA BTDC, calculate the igniter off time in step 92, set time coincidence interrupt B, and set the igniter on flag set in step 90. Take it down.

Next, the time coincidence interrupt A shown in FIG. 7 will be explained.

This interrupt routine is for finding the peak value of engine vibration. When the time set in step 87 in FIG. The peak hold value is input to the A/D converter 68 via the circuit 66 to start A/D conversion of the peak hold value, and the process returns to the main routine.

FIG. 8 shows the routine of time coincidence interrupt B, and the interrupt is performed when the time set in step 90 and step 92 of FIG. 6 comes. In step 94, it is determined whether the igniter on flag is set, that is, whether this flag is 1 or not. Turn off the igniter and return to the main routine.

FIG. 9 shows an A/D conversion completion interrupt routine, and this interrupt is performed when A/D conversion of the p1 background level and A/D conversion of the peak hold value are completed. First, in step 97, it is determined whether the knock gate is currently open. When the knock gate is closed, in step 98, the A/D conversion value converted in step 86 in FIG. Return. On the other hand, if the knock gate is open, the A/D conversion value converted in step 93 of FIG. .

FIG. 10 shows an interrupt routine that is performed every predetermined time (for example, 4 m5ec) for counting the time when no knocking occurs and the time for learning control. First, in step 102, a counter TIME is used to calculate the time when knocking does not occur.
The count value of I is incremented by 1, and in step 103, the count value of counter TIME2 for determining the learning control time is incremented by 1. In the next step 104, the count value of the counter TIMEI is 12 (48m115
e) Determine whether the following is true. If the count value exceeds 12, the count value 1 of the counter TIMEI is set to 12 in step 105, and if the count value is 12 or less, it is determined in step 106 whether the count value of the counter TIME20 is 12 or less. Here, if the count value exceeds 12, the count value of the counter TIME2 is set to 12 in step 107, and the process returns to the main routine. If 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. Step 88 Step 10 in Figure 6
A is compared with the peak value α stored as 0 and the value obtained by multiplying the background level b stored in the ninth step 98 by a constant Kt.

When the peak value α exceeds the value A, it is determined that knocking has occurred, and in step 110, the correction retard amount θK is increased by a predetermined angle (for example, 0.4° CA), and in step 112, knocking has occurred. The count value of the counter TIME1, which counts the time when no operation is performed, is cleared. On the other hand, when the peak value α is less than or equal to the value K11b, it is determined that knocking does not occur, and in step 109, it is determined whether the count value of the counter TIMEI is greater than or equal to a predetermined value (12), and the count value is determined to be a predetermined value. If the value is above, the state in which knocking does not occur has continued for a predetermined period of time, so in step 111 the correction retard amount θK is decreased by a predetermined angle (for example, 0.08° CA), and then in step 112 the counter TIME1 is Clear. Further, if the count value is less than the predetermined value in step 109, the process proceeds to step 113. In step 113, the basic ignition is activated as shown in equation (1) above using the corrected retard amount θ obtained as described above and the learned retard amount θKG obtained from the learning map by the two-dimensional interpolation method. Advance angle θBAsE'fr: Corrected and calculates the ignition advance angle θ2 for actually controlling the igniter.

Next, a routine for determining the learning retardation amount θKG corresponding to the current engine condition 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 knocking control area (Q
/N≧0.6) or knocking non-control region (Q/N<0.
6), and if it is in the knocking non-control region, the process proceeds to the main routine; if it is in the knocking control region, in step 114, the engine rotation speed N and load Q/
The RAM addresses of four points surrounding the point indicating the current engine condition determined by N are found on the learning map. Next step 1
In step 15, two-dimensional interpolation is performed based on the data stored in the four RAM addresses obtained, that is, the learning retardation amounts stored in the four RAM addresses (the routine of the two-dimensional interpolation method will be explained later). ), calculate the learning retard amount θKG at the point that indicates the current engine condition, and use the calculated value as RA.
It is stored in a predetermined location of M. In step 116, the tenth
It is determined whether the count value of the counter TIM11i1:2 for determining the learning control time counted in step 103 in the figure is greater than or equal to a predetermined value (for example, 12). If the count value is less than the predetermined value, return to the main routine; if the count value is greater than or equal to the predetermined value, proceed to step 1.
After clearing the count value of the counter TIME2 in step 17, the value of the corrected retard amount θ updated in steps 110 and 111 in FIG. 11 is determined in step 118, and learning is performed based on the value of the corrected retard amount. (The learning control routine will be explained later).

FIG. 13 shows a detailed routine of the two-dimensional interpolation method in step 115 of FIG. 12. In this two-dimensional interpolation routine, the map shown in FIG. 1 is used as a learning map, and four RAM addresses representing the current engine conditions are set as shown in FIG. Le+6, Le+7
shall be. First - in step 130, the current load Q
/N is the upper limit of the load on the learning map, that is, 1.2 [
It is determined whether it is less than or equal to L/raw, ). If the load exceeds 1.2 (t/rgv, :l, 1.2 is stored in the register Kasumi in step 131, and the load exceeds l,
If 'l, (l/rtv, 3 or less), the value of the current load Q/N is stored in the register in step 134. In step 135, the current engine speed N is equal to the engine speed on the learning map. upper limit of number i.e. 600
0Cr, p, m] Determine whether or not. If the engine speed exceeds 6000 (γ, p, m), 6000 is stored in register m in step 136, and if the engine speed is below 6000 [r, F, 71, step 137 Store the value of the current engine speed N in register m. In step 138, the value of the register haze is set to the lower limit of the load on the learning map, that is, o, 6.
(t/raw,) or more, and if the register haze value is less than 0.6, the register haze value i is set to 0.6 in step 139, and the register haze value is 0.6 or more. If so, the process proceeds to step 140. Then, in step 140, the value of register m is set to the lower limit of engine speed on the learning map, that is, 1000(r, 7
), and if the register-only value is less than 1000, the value of register m is set to 1000 in step 141, and the value of register m is set to 100.
If it is 0 or more, the process advances to the next step 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 le, respectively, and the current engine speed N and load Q/N are on the learning map. When the upper and lower limits of 1 are exceeded, the upper and lower limits are stored in registers m and 1, 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 (z/rgv, :) at address O from the value of the register Kasumi is stored in the register Kasumi. Next, in step 143, the value of the register haze is set to 0, 2, which is the load scale interval.
Divide by (1/rgv, ), store the integer part of the quotient in the register, and store the remainder of the quotient in the register y. The value of this register y is equal to the load value y from address 1 in FIG. 2 to the point representing the current engine condition. In addition, the integer part of the quotient stored in the register is the column of addresses closest to the point indicating the current engine condition and below the point indicating the current engine condition (horizontal arrangement of addresses, e.g. θ
5 is the first column).

Then, in step 144, the value of register y is further divided by 0.2 (t/reV,). Therefore,
Finally, the value corresponding to y/Y in the above-mentioned equation (6) is stored in register y.

In step 145, the value of the engine rotation speed at address θ is 1000Cr, p, m from the value of register m, as described above.
] is subtracted and the value is stored in a register, etc. Next, in step 146, the value of register m is divided by 1000 (r, p, m), which is the interval of 9 scales of engine speed, and the integer part of the quotient is stored in register m, and the remainder of the quotient is stored in register. Let X memorize it. This register
is equal to the engine speed value X from address 1 in FIG. 2 to the point indicating the current engine condition. In addition, the integer part of the quotient stored in register m is stored in 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, e.g. 016.12
．． 18th row is the first row). Then, in step 147, the value of register X is further divided by 1000 (r, p, m). Therefore,
Finally, in register X, x of equations (4) and (5) above
A value corresponding to /X is stored.

In the next step 148, the value of the register is multiplied by six and stored in the register, and in the next step 149, the value of the register and the register-specific value are added and stored in the register. As a result, the addresses of the lower left corners of the four points surrounding the current engine condition, that is, the address numbers of address 1 in FIG. 2, are determined and stored in the register.

In step 150, the learned retard amount θKGrL stored at address 1 on the learning map is read and stored in register A, and the learned retard amount θxa (kGrL) stored at address 1,001 is read. and store it in register B,
Learning retardation amount θKG (rL+
6) and store it in register C, and
The learning retard amount θxc(n+7) stored at address 7 is stored in the reading 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. Also, in step 152, the value of register D is subtracted from the value of register C, and the value of register X is multiplied,
Furthermore, the value of register C is added to this value and the result 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 retard amount be θKG.

Next, the learning control in step 118 in FIG.
This will be explained in detail based on FIG. 4 and FIG. 15. In step 160, it is determined whether the corrected retard amount θK is equal to or greater than a first predetermined crank angle (for example, 2° CA). If it is determined in step 160 that the corrected retardation amount θK is less than the first predetermined crank angle, in step 161 the learning value α is set to a first predetermined value (0 or a positive or negative value, for example -0, 12 °CA) and the process proceeds to step 164. On the other hand, if it is determined in step 160 that the corrected retard amount is equal to or greater than the first predetermined crank angle, then in step 162 the corrected retard amount θK is set to a second predetermined value larger than the first predetermined crank angle. It is determined whether the crank angle is greater than or equal to the crank angle (for example, 4° CA). When the corrected retard amount θK is 46CA or more, the following routine is executed and the corrected retard amount θK is 4°C.
If it is less than A, in step 163 the learning value α is set to a second predetermined value (for example, 0.12° CA) and the process proceeds to step 164.

Steps 164 to 167 show a learning control routine, and using the value x1y that was once stored in the register in steps 144 and 147 in FIG. learning value α
Learning control is performed by distributing the information.

θKGL ← θKGL+ α(1-rXl-y)
・・・・・・・・・・・・・・・・・・・・・・・・(
11) θKG (rL-1-1) 80KG (m+ 1)
+αx(1-y) −・・・・・・・・・・・・・・・・
...(6) θxc(rL+6)←θKG(rL+6)
+α(1-x)y ・・・・・・・・・・・・・・・
...(2) θKG(rL+ 7)←θKG(rL+
7)+αxy・・・・・・・・・・・・・・・・・・
. . . α → Upper A detailed routine for distributing the learned value tube will be explained based on FIG. 15. In step 170, the learning value α is multiplied by X to obtain α.
In step 171, α obtained in step 170 is subtracted from the learning value α, and the value is set as α. Step 17
In step 2, α obtained in step 171 is multiplied by y and temporarily stored in register α'. When the value of this register α' is expressed using the learning value α, it becomes α(1−x)y, which is the learning amount of address +6.

In the next step 173, the value of register α' is subtracted from α obtained in step 171 and stored in register α. The value of this register α is α(1-T,)(1-y)
This is the amount of learning for Tonashi and Ru addresses. Also, step 174
In step 170, α obtained in step 170 is multiplied by y and stored in register α''.

The value of this register α″′ becomes αxy, which is the learning amount at address 1,700.Then, in step 175, the value of register α″′ is subtracted 17 from α obtained in step 170, and the result is stored in register α. do. The value of this register α is αx(1−y), which is the learning amount of address +1.

As a result of the above, the amount of learning at addresses near the point indicating the current engine condition is large, and the amount of learning at addresses far from the point indicating the engine condition is small, and the learning is controlled as shown in the table below. Learning control is performed so that the corrected retard amount falls within a predetermined range according to the magnitude of the corrected retard amount.

Further, FIG. 16 shows changes in the corrected retard amount θ, one learning retard amount θKG, and ignition timing θiy over time. As can be understood from the figure, when the corrected retard amount θK is within a predetermined range, the learned retard amount θKG is constant, and the corrected retard amount θK
The learned retard amount θKG increases when θK exceeds a predetermined range, and decreases when the corrected retard amount θK is less than a predetermined range.

Furthermore, FIG. 17 shows the variation in ignition timing corresponding to the engine speed. In Fig. 16, curves C8 to C3 are the third
It is understood that the corrected retardation amount θK is always constant regardless of whether knocking is likely to occur or knocking is unlikely to occur.

Next, another embodiment of the learning control of the present invention will be described in detail using FIG. 18. Note that in FIG. 18, the same parts as in FIG. 14 are designated by the same reference numerals, and explanations thereof will be omitted. In this embodiment, learning control is performed by varying the amount of learning between the knocking control area inside the learning map and the knocking control area outside including the boundary of the learning map.

In step 180, the current engine speed N is the lower limit value of the learning map t o OO(r, p, m
] In step 181, the current engine speed N is set to 6o, which is the upper limit of the learning map.
Determine whether it is smaller than oo(y, p, m). Also, in step 182, it is determined whether the current load Q/N is larger than the lower limit of the learning map, Q,5 [A/ rgv,), and in step 183, the current load Q/N is determined as the lower limit of the learning map. The upper limit is 1, 2(t/rg
v, :] Determine whether it is smaller than the value. If the engine speed is below the lower limit of the learning map or above the upper limit of the learning map, the learning value α is reduced to 1/2 in step 184, and this learning value is distributed in steps 164 to 167. learning control. If the load is greater than or equal to the lower limit value of the learning map or the upper limit value of the learning map, the learned value is set to the size of α't-1/2 in step 185, and this learned value is distributed in steps 164 to 167. to perform learning control. Further, when the current engine speed and load are within the upper and lower limit values, learning control is performed by leaving the learning value α unchanged and distributing this learning value in steps 164 to 167.

According to this embodiment, since the learning value is changed depending on the area, learning control can be performed in the same way both inside and outside the learning map, and the accuracy of learning control outside the learning map is improved. Furthermore, since opportunities for learning control are increased, it is possible to quickly respond to changes in the learning map due to changes in various conditions.

In addition, although the example in which learning control is performed so that the correction retard amount is within a predetermined range has been described above, the present invention is not limited to this. It can also be applied to the case where the learning control is performed in such a way that the entire learning map is advanced.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the learning map, Fig. 2 is an explanatory diagram showing a point indicating the current engine condition and the four points surrounding this point, and Fig. 3 is a diagram showing the relationship between engine speed and ignition timing. ,
FIG. 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. FIG. 8 is a flow chart of time match interrupt A, FIG. 9 is a flow chart of time match interrupt B, and FIG. 9 is a flow chart of A/D completion interrupt routine.
Fig. 10 is a flowchart showing the interrupt routine every 4 m5ec, Fig. 11 is a flowchart of the routine for updating the correction retardation amount, Fig. 12 is a flowchart of the learning control routine, and Fig. 13 is a flowchart of the routine for updating the correction retardation amount.
A flowchart of the dimensional interpolation routine, FIG. 14 is a flowchart of the learning control routine of the embodiment of the present invention shown in FIG. 12, FIG. 15 is a flowchart of the routine that distributes all learned values, and FIG. 16 is a flowchart of the correction retardation amount with respect to the passage of time.・Diagram showing the variation of learning retardation amount and ignition timing, Figure 17 is a diagram showing the relationship between engine speed and ignition timing similar to i31￥1 ・Diagram showing the relationship between corrected retardation amount and learning retardation amount , FIG. 18 is a flowchart of the learning control routine of another embodiment of the present invention shown in FIG. 2... Air flow meter, 12... Fuel P) injection valve,
18... Knocking sensor, 32... Engine rotation angle sensor, 34... Electronic control circuit. Figure 1 Figure 2 Figure 11 Figure 12 Figure 14-408- Figure 15

Claims (1)

[Claims] (1) The learned retard amount is changed by learning control to a predetermined address corresponding to the engine operating conditions expressed by engine speed and load, and the learning retardation amount is stored to bring the knocking level to a predetermined level. The learning control is performed by adding or subtracting a predetermined value to the learning retard amount at a specific address surrounding the engine operating condition, and the learning retard amount corresponding to the current engine operating condition is determined based on the learning retard amount at the specific address. Knocking is determined by subtracting the sum of the learned learning retardation amount and the corrected retardation amount for retarding the ignition timing in response to knocking from the basic ignition advance angle determined according to the engine operating conditions. In the knocking control method for an internal combustion engine, the predetermined value is distributed at a ratio of the difference between the current engine speed and the engine speed at the specific address to the difference in engine speed between the specific addresses; The distributed predetermined value is further distributed at a ratio of the difference between the current load and the load at the specific address to the difference in load between specific addresses, so that the amount of learning at the specific address close to the current engine operating condition becomes large and A knocking control method for an internal combustion engine, characterized in that the amount of learning at a specific address far from current engine operating conditions is reduced.