JPS59113267A - Control of knocking in internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the fluctuation of torque as well as the reduction of output by keeping the learned delaying amount of a spark angle in accordance with the knocking in constant under a light load. CONSTITUTION:In a step 122, the load Q/N is decided whether it is higher than 0.6(l/rev) or not or whether it is in a knocking control area or not. If the load Q/N is lower than 0.6(l/rev), an ignition timing is set to thetaBASE (step 123). According to this method, the fluctuation of torque or the reduction of output may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a knocking control method for an internal combustion engine, and particularly relates to a corrective retardation amount for performing retarding at a relatively fast speed depending on the presence or absence of knocking, and a method for controlling knocking 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 a basic ignition advance angle by retarding the ignition angle and using a learning retard amount changed by learning control.

The conventional knocking control method using learning control is based on the ratio Q of the engine rotation speed N1 and the intake air amount Q and the engine rotation speed N.
/ The basic ignition advance angle θBA811, which is predetermined by the load determined by N or intake pipe negative pressure, is stored in the read-only memory (ROM) K map of the microcomputer, and the igniter is actually activated based on the following formula (1). The ignition advance angle θ1g is calculated, and the knocking control is performed using this ignition advance angle. Furthermore, learning control and knocking control are not performed in a light load region such as when idling because knocking does not occur.

θig = θB person sw - (θKG + θK)...
...Song (1) However, θKG is the learning retardation amount, θ, which is determined by the engine speed and load and changed by learning control in order to bring the knocking level to a predetermined level.
X is a correction retard amount that retards the ignition timing when knocking occurs and advances the ignition timing when knocking no longer occurs.

Therefore, the corrected retard amount θ can be obtained as follows.

First, engine vibration is detected using a knocking sensor composed of a microphone, etc., and the engine vibration peak value a is multiplied by a predetermined times the average value (background) b of engine vibration (where K is a proportionality constant). and compare this peak value with the value of b. The peak value a is x,
When the value of b is exceeded, it is determined that knocking has occurred, and the correction retard amount θK is set so that the ignition timing is delayed by a predetermined crank angle (for example, 0.4° CA) per knocking occurrence, as shown in the following equation (2). change.

θ work ← θ 10, 4° OA ・・・・・・・・・・・・
・・・・・・・・・・・・・・・(2) Also, when the peak value a is less than the value b, it is determined that knocking has not occurred, and the first timer is used to calculate the For example 4
8 m6θC) has elapsed, and when a predetermined time has elapsed, the corrected retardation amount θK is changed so that the ignition timing advances by a predetermined crank angle (for example, 0.086CA) as shown in the following equation (3). .

To θ←θxO, 08°CA・・・・・・・・・・・・
(3) Further, the learning retardation amount θK() according to the engine conditions is calculated as follows. first,
As shown in Figure 1, engine speed N and load Q/N
Addresses 0 to 23 where learning delay angle amounts are stored in correspondence with the microcomputer's random access memory (RA
M) and create a learning map. Take the engine speed N and intake air amount Q, and surround the point ('%Q/'') indicating the current engine condition on the learning map.
Find the RAM address of the point. Now, as shown in Figure 2, the RAM address surrounding the point indicating the current engine moxibustion point is n(
n+=Q, l,...16), n+1, n
+6, n+7, address n has the learning retard amount θxGn, address n+1 has the learning retard amount θto(n++1, address n+6 has the learning retard amount θKG(n+l111, address n+7 has the learning retard amount θK(1(n+t) ) are stored respectively. Then, the difference in engine speed between addresses is x1, the difference in load between addresses is the difference in engine speed between address Y1 and the point indicating the current engine condition. If the difference in load between address The learning retardation amount θK(i) of the point shown is determined.

7(A-B) θ=□10A...Mercury (6) ICG y 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 whether the engine is running or not are prepared. A second timer is used for a predetermined period of time (for example, 46 m5e
c) When it is detected that the corrected retard amount θK has been changed to exceed a predetermined crank angle (for example, 4° CA), it is determined whether the corrected retard amount θK has exceeded the predetermined crank angle. At times, a predetermined crank angle (for example, 0.04° CA) is added to the learning retardation amount at four points on the map surrounding the point indicating the current engine condition described above. As a result, the learning retard amount is learning-controlled so that the ignition timing is delayed. On the other hand, a third timer is used for a predetermined period of time (for example, 16 (6)).
When it is detected that the ignition timing has elapsed, a predetermined crank angle (for example, 0.01'CA) is subtracted from the learning retard amount of all addresses on the learning map regardless of the presence or absence of knocking, so that the ignition timing is learned to advance. Learning and controlling the amount of retardation.

Using the corrected retardation amount θ changed as described above and the learning retardation amount θKG obtained by the two-dimensional interpolation method from the learning map subjected to learning control, the basic calculation is performed based on the above formula +11. Knocking is controlled by correcting the ignition advance angle θBA811.

However, in such conventional knocking control methods, learning control is performed within the knocking control area without performing learning control in the light load area (area where knocking does not occur) outside the knocking control area. There is a problem in that when engine operating conditions change within the knocking control region, there is a sudden change from a state with no retard amount to a state with a retard amount, resulting in torque fluctuations. In addition, if engine operating conditions exist in the knocking control region close to the light load region, if knocking occurs frequently and the corrected retardation amount becomes, for example, 4° CA or more, the learning retardation amount on the light load region side will increase. Since the learning retardation amount is maintained by learning control, when the engine operating conditions enter the light load side knocking control region from outside the knocking control region, the learning retardation amount learned above will increase. There was a problem in that the ignition timing was controlled too late, causing a decrease in output and deterioration of fuel efficiency.

The present invention has been made to solve the above-mentioned problems, and is designed to prevent torque fluctuations and output decreases due to ignition timing delays when the load changes from a knocking non-control area to a knocking control area. An object of the present invention is to provide a knocking control method for an internal combustion engine.

In order to achieve the above object, the present invention provides a method for controlling knocking by subtracting the sum of a corrected retard amount and a learned retard amount from a basic ignition advance angle. The learning retardation amount is set to a constant value. Preferably, this constant value is zero.

According to the above configuration of the present invention, since the amount of learning retardation at light load is kept constant, the change in ignition timing from light load to high load is smooth, and the ignition timing is not retarded excessively, resulting in output. This has the unique effect of improving

In addition, as shown in FIG. 3, the basic ignition advance angle θBAIII
+ That is, M B T (Minimum 5park
Advance for Bθst TO? guθ) is a curve C depending on the engine speed.

The ignition timing at which knocking occurs when knocking is difficult to occur, such as when the air is humid, is as shown by curve C7, and when knocking is likely to occur, such as when the air is dry, the ignition timing changes as shown in curve C7. The ignition timing at which slight knocking occurs is as shown by curve C8. Therefore, the ignition timing at which minute knocking occurs varies depending on the engine speed and environmental conditions. Therefore, in the above configuration of the present invention, in order to control knocking in the same way under operating conditions where knocking is likely to occur and operating conditions where knocking is unlikely to occur, the percentage constant is set so that the corrected retardation amount falls within a predetermined range. It is preferable to perform learning control on the learning retardation amount excluding the learning retardation amount.

Next, FIG. 4 shows an example of an engine to which the present invention is applied. This engine has an air cleaner (
An air flow meter 2 is provided as an intake air amount sensor provided on the downstream side of the engine (not shown). The air flow meter 2 includes two compensation motion plates 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 a surge tank 8 is arranged 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 disposed protruding 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 14A of the engine body 14.
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 and configured to detect vibrations of the engine. In addition, 20 is a spark plug, 2
2 is 0.0 to control the air-fuel mixture to near the stoichiometric air-fuel ratio. A sensor 24 is a cold/hot water temperature sensor that detects the engine cooling water temperature.

The spark plug 2o 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 3o 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 3o outputs a cylinder discrimination signal to an electronic control circuit 34 made up of 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. The angular 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) 4
0, a clock (CLOCK) 41, a first input/output boat 42, a second input/output boat 44, a first output boat 46, and a second output boat 48. RAM 36, ROM 38, CPU 40. C.L.O.
CK41, first output boat 42, second input/output boat 44, first output boat 46, and second output boat 4
8 are connected by a bus 50. The first input/output port 42 includes a buffer (not shown) multiplexer 5
4. An air flow meter 2, a cooling water temperature sensor 24, an intake air temperature sensor 4, etc. are connected via an analog-digital (A/D) converter 56. The multiplexer 54 and A/D converter 56 are controlled by a signal output from the first input/output port 42. The second input/output port 44 is connected to the sensor 22 via a buffer (not shown) and a comparator 62, and the cylinder discrimination sensor 3o and engine rotation angle sensor 32 are connected to the waveform shaping circuit 641'i. has been done. The second input/output boat 44 also includes a band pass filter 60, a peak hold circuit 61, a channel switching circuit 66, and an A
The knocking sensor 18 is connected via a /D converter 68. This bandpass filter is an integrator circuit 63
The channel switching circuit 66 is connected to the channel switching circuit 66 via the channel switching circuit 66. This channel switching circuit 66 includes a peak hold circuit 6.
1 and the output of the integrating circuit 63.
Second input/output port 44 for input to D converter 68
A control signal output from the peak hold circuit 61 is inputted, and a seven-bit signal from the second input/output port 44 is inputted to the peak hold circuit 61. Further, the first output boat 46 is connected to the igniter 28iC via a drive circuit 7o, and the second output boat 48 is connected to the fuel injection valve 12 via a drive circuit 72.

The ROM 38 of the electronic control circuit 34 stores in advance a map of the basic ignition advance angle θBA811 expressed by the engine speed and intake air amount, the basic fuel injection amount, etc.
The basic ignition advance angle and basic fuel injection amount are read out from the signals from the air flow meter 2 and from 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 read out. A corrected ignition advance and a corrected fuel injection amount are added to the basic ignition advance and basic fuel injection amount to control the igniter 28 and the fuel injection valve 12. The air-fuel ratio signal output from the Ol 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 the detailed explanation 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 the explanation 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 for each 306CA 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 to the band pass filter 60. , A/D via the integration circuit 63 and channel/channel switching circuit 66
Converter 68 initiates an A/D conversion of the average or background level of engine vibration. Subsequently, in step 87, the closing side t1 of the knock gate is
%, that is, the next time to close the knock gate, and set the time coincidence interrupt A.

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

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, and when the time set in step 87 in FIG. The peak hold value is inputted to the A/D converter 68 via A/D converter 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 the background level A/D conversion and the peak hold value A/D conversion are completed. First, in step 97, it is determined whether the knock gate is currently open. When the knock gate is closed, the sixth
The A/D conversion value converted in step 86 in the figure is stored in the RAM.
36 and set as background level b, the knock gate is opened in step 99 and the process returns to the main routine. On the other hand, in the case where the knock gate is open, the A/D conversion value converted in step 93 of FIG. 7 is stored in the memory of the RAM 36 and set as the peak value a.
In step 101, the knock gate is closed and the process returns to the main routine.

FIG. 1O shows an interrupt routine that is performed every predetermined time (for example, 41i1111θC) for counting the time when no knocking occurs and the time for learning control. First, in step 102, a counter TIM is used to calculate the time when knocking does not occur.
The count value of EII is increased by 1, and the count value of counter MK2 for determining the learning control time is increased by 1 in step 103.

In the next step 104, the counter T-work M1! ! 1
It is determined whether the count value of is less than or equal to 12 (48m5ec). If the count value exceeds 12, the count value of the counter T Mll 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 TIMK2 is 12 or less. . Here, if the count value exceeds 12, step 10
At step 7, the count value of the counter TIME2 is set to 12 and the process returns to the main routine, and 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 become 90°OA BTDCK, in step 122 the load Q/N is 0.6 (e/rθv
, ] or more, that is, whether or not it is in the knocking control region. Step 1 if not in knocking control area
23, the basic ignition advance angle θBA811 is set to ignition advance angle 01g, and when it is in the knocking control region, in step 108, the peak value a stored in step 100 of FIG.
and b are compared with the value obtained by multiplying the background level b stored in step 98 of FIG. 9 by a constant K.

When the peak value a exceeds the value Kab, it is determined that knocking has occurred, and in step 110 the corrected retard amount θK is increased by a predetermined angle (for example, 0.4° OA), and in step 112, the time during which knocking does not occur is determined. Clear the count value of counter TIMKI. On the other hand, when the peak value a is equal to or less than tl, it is determined that knocking is desired to occur, and in step 109, the count value of the counter MK1 is set to a predetermined value (12).
If the count value is greater than or equal to a predetermined value, it means that a 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 set to a predetermined angle (for example, 0.08°OA), the counter T-MKI is cleared in step 112. Further, if the count value is less than the predetermined value in step 109, the button advances to step 113. In step 113, the basic ignition advance angle 011 is determined by the corrected retard amount θX obtained as described above and the learned retard amount θKG obtained from the learning map by the two-dimensional interpolation method, as shown in the above-mentioned equation (1). The ignition advance angle θ1g that actually controls the igniter is calculated by correcting the human 8g.

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 load Q/N is 0.6
It is determined whether or not it is greater than or equal to (l/rev,), that is, whether or not it is in the knocking control region. When it is not in the knocking control area, that! Continuing to the main routine, if it is in the knocking control region, in step 114 the RAM addresses of four points surrounding the point indicating the current engine condition determined by the engine speed N and the load Q/N are found on the learning map. . Next, in step 115, the obtained four points of RAM
The data stored at the address, that is, 4 points of RAM
Based on the learning retardation amount stored at the address, the learning retardation amount θKG at the point indicating the current engine condition is calculated using the two-dimensional interpolation method (the routine of the two-dimensional interpolation method will be explained later). Then, the calculated value is stored in a predetermined location in the RAM. In step 116, it is determined whether the count value of the counter MK2 for determining the learning control time counted in step 103 in FIG. 10 is greater than or equal to a predetermined value (for example, 12). If the count value is less than a 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 MK2 is cleared in step 117, and then steps 110 and 111 in FIG. In step 118, it is determined whether or not the corrected retardation amount θK updated in is equal to or greater than a first predetermined crank angle (for example, 2° OA).

If it is determined in step 118 that the corrected retard amount θK is less than the first predetermined crank angle, step 121
, performs learning control to subtract a predetermined crank angle (for example, 0.04° OA) from each of the learning retard amounts stored at four points on the learning map surrounding the point indicating the current engine condition, and then returns to the main routine. Return. As a result, when the corrected retard amount θ is less than the first predetermined crank angle, learning control is performed so that the learning retard amount of the learning map becomes smaller, and the ignition timing is controlled to advance according to the learned retard amount. . On the other hand, if it is determined in step 118 that the corrected retard amount θK is greater than or equal to the first predetermined crank angle, then in step 119 the corrected retard amount θK is set to a second value larger than the first predetermined crank angle. at a predetermined crank angle (e.g. 4°
CA). If it is determined in step 119 that the corrected retard amount θK is less than the first predetermined crank angle, that is, if the corrected retard amount θK 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 performing learning control.

As a result, when the corrected retard amount θK takes a value within a predetermined range, learning control is not performed, and the ignition timing may be 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 retard amount θK is greater than or equal to the second predetermined crank angle, step 12
At 0, learning control is performed to add a predetermined crank angle (for example, 0.04° CA) to each of the learning retard amounts stored at four points on the learning map surrounding the point indicating the current engine condition, and the main routine Return to.

As a result, when the corrected retard amount θK is equal to or greater than the second predetermined crank angle, learning control is performed so that the learning retard amount of the learning map becomes larger, and the ignition timing is controlled to be delayed by the learned retard amount.

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 of values.

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

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 Figure 1 is used as a learning map, and the four RAM addresses representing the current engine conditions are set as n, n-1-1, n, as shown in Figure 2. -4-6,
Let it be n+7. First, in step 130, it is determined whether the current load Q/N is less than or equal to the upper limit of the load on the learning map, that is, 1.2[//rev,"1. If the load is 1.2C1/rev, ], 1.2 is stored in register n in step 131, and if the load is less than 1.2 [l/rev, "1", the current value of load Q/N is stored in step 134. is stored in register n. 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 (r-p-m), 6000 is stored in register m in step 136, and if the engine speed is less than 6000 (r-p-m:l), step 136 stores 6000 in register m. At step 137, the value of the current engine speed N is stored in register m. At 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 [:l/rev,]. 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 1
Proceed to 40. Then, in step 140, the value of register m is set to the lower limit of engine speed on the learning map, that is, 1.
000(:r-pzm” determine whether it is greater than or equal to 1,
When the value of register m is less than 1000, the value of register m is set to 1000 in step 141, and when the value of register m is 1000 or more, the next step 1 is performed.
Proceed to step 42. 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 stored 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 (l/rθv, ) at address θ from the value of register n is stored in register n.Next, in step 143, the value of register n is set to the load scale. 0, 2 (l
/rev, ], the integer part of the quotient is stored in register nVC, and the remainder of the quotient is stored in register y. The value of this register Y is equal to the load value y from address n in FIG. 2 to the point representing the current engine condition. 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 arrangement of addresses, e.g. O
5 is the first column).

Then, in step 144, the value of register y is further divided by 0.2 (1/ray.).Therefore, finally, register y contains the value corresponding to 7/Y in equation (6). remembered.

At step 145, the value of the engine rotation speed at address θ is calculated from the value of register m, as described above.

The value obtained by subtracting (r*p*m:) is stored in register m. Next, in step 146 register m
The value of 1000 (j
m p @ m :), the integer part of the quotient is stored in register m, and the remainder of the quotient is stored in register X. The value of this register X is equal to the value X of the engine speed from address n in FIG. 2 to the point indicating the current engine condition. Further, 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... 12.18 is the first row). Then, in step 147, the value of register X is further divided by 1ooo(r・p・m). Therefore, finally, register is memorized.

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

In step 150, the learning retard amount θKOn stored at address n on the learning map is read out and stored in register A, and the learned retard amount θKo(n++) stored at address n+1 is read out and stored in register B. memorize it,
Learning retardation amount θKG (n+,
) is read out and stored in register C, and the learning retard amount θtG(n+y) stored at address n+7 is read out and stored 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. 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 y, 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 θxa.

Next, a detailed routine of steps 118 to 121 in FIG. 12 is shown in FIG. Note that the register n in FIG. 14 is the register n of the two-dimensional interpolation routine in FIG. 13. First, in step 118, it is determined whether the corrected retard amount θ is equal to or greater than 2° CA in the same manner as described above. If the corrected retard amount θK is less than 2°OA, the learned value α is set to −0.04°CA in step 160, and the process proceeds to step 162. Correction retard amount θK is 2°CA
In the above case, in step 119, the correction retard amount θ
Determine whether X is greater than or equal to 4° CA. If the corrected retard amount θK is less than 4° CA, return to the main routine, and if the corrected retard amount θX is 4° CA or more, set the learning value α to 0.04° CA in step 161 and proceed to step 162. move on. In step 162, the load Q/N is set to the lower limit value of the learning map 0, 6 (lj/rev,)
Determine whether or not the above is true. If the load is 0.6 or more, it is determined in step 166 whether the engine speed N is more than the lower limit value 1000 (rapem) of the learning map, and if the load is less than 0.6, step 166 is performed. At 163, the engine speed N is 1000 (rap
Determine whether it is less than or equal to @ml.

In step 166, the engine speed N is 1000 [
r-p-m], step 16
7, the previously learned learning delay amount θ at address n
Learning control is performed in which learning value α is added to KGn,
In step 168, learning control is performed in which the learned value α is added to G(n++) to the previously learned learning retard amount θ at address n+1, and the process returns to the main routine. Here, as mentioned above, the current engine speed N and load Q/N are Q/N22.61J'/rev,]
If it exists in the area of N (1000 [r - p - m), the value of register n indicating the RAM address can take 0.6.12.18 in the first row, so the current engine If the point indicating the condition exists in the above area, the learning retard amount at address 0°6.12.18 is controlled in step 167, and the learning retard amount at address 1,7.13.19 is controlled in step 168. The amount is controlled by learning.

In step 166, the engine speed N is 1000 (
r-p-m”] or more, step 1
In step 69, learning control is performed in which the learning value α is added to the previously learned learning retard amount θK11) at address n. The point indicating the current engine condition is Q/N≧0.6 (1
/rev,) and N≧1000 (r-p-m), the value of register n indicating the RAM address can take a value from 0 to 23, so in step 169 all addresses are Becomes subject to learning control.Next step 1
At step 70, it is determined whether the value of register n is not 23 or not. If the value of register n is not 23, step 17
1. In steps 173 and 174, whether the value of register n is not 17 or 11, respectively, 5
Determine whether or not. The value of register n with 5.11
．． 17.23 represents the number jth on the 6th line. When the value of register n is 23, the process directly returns to the main routine. The learning retardation amount at address 23 at this time is subjected to learning control in step 169. If the value of register n is 17.11.5, step 17
Step 17: Decrease the value of the euteresistor n by 1 to 2.
At step 8, learning control is performed to add the learning value α to the learning retard amount θxe (n+t>) at address n+7, and the process returns to the main routine. Therefore, the value of register n is 17.11.
．． 5, the learning retard amounts for addresses 17.11.5 are each controlled in step 169, and the learning retard amounts for addresses 23.17.11 one column above are each controlled in step 178. I'm smiling.

When the value of register n is not 23, 17, or 11.5, in step 175, learning control is performed in which the learning value α is added to the learning delay amount θxa (n−+−+ 1) at address n+1. That is, if the RAM address obtained in step 149 of the two-dimensional interpolation routine is not on the sixth row, in steps 169 and 175, the RAM address obtained in the two-dimensional interpolation routine and the address to the right of this address are is learning controlled.Step 176
Then, it is determined whether the value of register n is less than 17, and if the value of register n is 17 or more, the process returns to the main routine. That is, when the RAM address is 18 to 22 in the fourth column, learning control is performed on the address stored in register n and the address to the right of it in steps 169 and 175. On the other hand, when the value of register n is less than 17, that is, when there are four addresses surrounding the point indicating the current engine condition, in step 177, the learning retard amount θKG (n+e l is set to learning value α) at address n+6. Learning control is performed to add , and step 178
Then, learning control is performed to add the learning value α to the learning retard amount θKG (n+t) at address n+7. As a result, if there are four addresses surrounding the point indicating the current engine condition, step 169, step 175, step 17
7 and step 178, the learning retard amounts of the four addresses are learning controlled.

In step 162, the load is 0. fi [: l/rev
, if it is determined that the engine speed is less than 3, it is determined in step 163 whether the engine rotation speed is 1000 (r-psm) or less, and if the engine rotation speed is 101000 (r-p- or less), the register is Subtract 7 from the value of n,
Learning control is performed in step 178. The point indicating the current engine condition is Q/N (0,6 [1/rev, ) and N
When present in the region of ≦1000 [rpm),
Since the value of register n is 0, step 1 in this case
In step 78, the learning retardation amount at address 0 is subjected to learning control. On the other hand, the engine speed N is 1000 [rapan:
], it is determined in step 164 whether the value of register n is divided by 5, and if it is not 5, 6 is subtracted from the value of register n in step 179,
In steps 177 and 178, learning control is performed on the learning retard amounts at addresses n+6 and n+7.

When the value of register n is 5, 7 is subtracted from the value of register n in step 180, and learning control is performed in step 178. The point indicating the current engine condition is Q/N
(0,6(l/rev,) and N〉1ooo(r-p
-m), the value of register n can take the value of the address in the first column, so if the value of register n is 5, the learning delay amount at address 5 is controlled by learning in step 178. , when the value of register n is 0.1.2.3.4, register n is set in step 177 and step 178.
The learning delay amount of the address with the value of and the address to the right of the address is controlled by learning.

Learning retardation amount θI in the learning routine shown in FIG. 14 above
The following table summarizes the relationship between the conditions for adjusting the corrected retard amount θ and the increase/decrease in the learned retard amount θKG when cG is updated by learning control.

In addition, FIG. 15 shows changes in the corrected retard amount θK, learned retard amount θKG, and ignition timing 01g 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 when the corrected retard amount θK exceeds the predetermined range, the learned retard amount θ increases. and decreases when the corrected retard amount θK is less than a predetermined range.

Furthermore, FIG. 16 shows variations in ignition timing corresponding to engine speed. In Fig. 16, curves 01 to C3 are the same as those in Fig. 3, and it is understood that the corrected retardation amount θK is always constant whether knocking is likely to occur or knocking is unlikely to occur. .

After the above learning control routine is performed, a routine shown in FIG. 17 for keeping the learning retard amount at a specific address on the light load side constant is performed. This routine follows the learning control routine shown in FIG. 12, and after this routine ends, the main routine continues. In step 190,
A specific RAM address with a predetermined load or less on the light load side on the learning map shown in FIG. .9
．． 10.11) is rewritten to a predetermined crank angle (for example, 0° CA).

By setting the specific learning retardation amount on the light load side to a constant value as described above, the required retardation amount (+θKG for θ) from the basic ignition advance angle for the load Q/NK is shown in Figure 18. Becomes a characteristic. Figure 18 shows the engine speed at 2000 (r-p・m).
], 4000 (r@p@m), but on the light load side, the ignition timing at which knocking occurs is advanced from the basic ignition advance angle, and the learning retardation amount is set to 0°C.
It can be seen that since A is set to a constant value, the required retardation amount is QOCA, and the rise of the retardation amount is smooth.

In addition, Fig. 19 shows the engine rotation speed 2ooo (r・p *
The characteristic curve of the ignition timing at which knocking occurs with respect to the load Q/N at [m] is shown by a solid line. The dashed line is the characteristic of the basic ignition advance angle.

[Brief explanation of drawings]

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. figure,
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 retard 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 showing details of the learning routine, FIG. 15 is a diagram showing changes in correction retardation amount, learning retardation amount, and ignition timing over time, and FIG. 16 is a flowchart showing the details of the learning routine. A diagram showing the relationship between the engine speed and ignition timing, the relationship between the corrected retard amount and the learned retard amount, similar to Figure 3;
Fig. 17 is a flowchart showing a routine for setting a specific learned retard amount to a constant value, Fig. 18 is a diagram showing the characteristics of the required retard amount with respect to the load, and Fig. 19 shows the characteristics of the ignition timing with respect to the load. FIG. 2... Air flow meter, 12... Fuel injection valve, 1'8... Knocking sensor, 32... Engine rotation angle sensor, 34... Electronic control circuit. Agent Tatsuyuki Unuma (and 2 others) Figure 11 Figure 12 439- 1.2 1.4 Cノ/reV')

Claims (3)

[Claims] (1) From the basic ignition advance angle determined by the engine speed and load, the learned retard amount is set at a constant value t, b depending on the engine speed and load and is changed by learning control in order to bring the knocking level to a predetermined level. In a knocking control method for an internal combustion engine that controls knocking by subtracting the sum of a correction retard amount that retards the ignition timing when knocking occurs and advances the ignition timing when knocking no longer occurs, a predetermined value on the light load side is used. A knocking control method for an internal combustion engine, characterized in that a specific learning retardation amount is set to a constant value under a load. (2) Claim 1 in which the certain value is zero
Knocking control method for an internal combustion engine as described in . (3) Any one of Claims 1 and 2, characterized in that the learned retard amount excludes the specific learned retard amount so that the corrected retard amount falls within a predetermined range of values. The described knocking control method for an internal combustion engine.