JPS59138773A - Control method for knocking of internal-combustion engine - Google Patents

Abstract

PURPOSE:To have smooth control of ignition timing by stopping the study control of the amount of study angle delay in a specific range including light load, and by giving a constant value to the specific study control amount or the light load side in said specific range. CONSTITUTION:At Step 125 is judged whether the number of engine revolution H is below 3,000rpm, and if it turns out to be YES, it shall be judged at Step 126 whether the load Q/N is over 0.81/rev. If the number of engine revolutions is over 3,000rpm, it shall be judged at Step 126 whether the load is no more than 0.8l/rev. Then the study cotrol made at Steps 120, 121 is stopped in the specific range including light load. In this case, the amount of study control is held at a constant value. Thereby the ignition timing can be controlled smoothly.

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 retarding the ignition angle and correcting the basic ignition advance angle using a learning retard number changed by learning control.

The conventional knocking control method using learning control is based on the engine speed N, the ratio Q between the intake air IQ and the engine speed N.
/N or the load determined by the intake pipe negative pressure, the basic ignition advance angle θBAsK is stored in the read-only memory (ROM) of the microcomputer in the form of a map, and the igniter is actually activated based on the following equation (1). The ignition advance angle θheel is calculated and the knocking control is performed using this ignition advance angle. In addition, knocking does not occur under light loads such as during idling, so
Knocking control is not performed.

θig=θBA81C-(θKG+θK)°°°01°
(1) However, θKG is a learning retardation amount that is changed by constant and learning control depending on the engine speed and load in order to bring the level of knocking to a predetermined level. This is a correction retard amount that advances the ignition timing when knocking no longer occurs.

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

First, engine vibration is detected using a knocking sensor configured with a microphone, etc., and a predetermined times Kb (where K is a proportionality constant) of the average value (background) b of engine vibration and the peak value a of engine vibration are calculated. The peak value a and the value of Kb are compared. The peak value a is Kb
When the value exceeds 1. When it is determined that knocking has occurred, the correction retard angle θK is changed so that the ignition timing is delayed by a predetermined crank angle (for example, 0.4° CA) per occurrence of knocking, as shown in the following equation (2).

+04°CA in θ - θ +04°CA (2) Also, when the peak value a is less than the KbO value, it is determined that knocking has not occurred, and the first timer is used to It is determined whether a predetermined time (e.g., 48 msec) has elapsed, and when the predetermined time has elapsed, the ignition timing is corrected to advance by a predetermined crank angle (e.g., 0.08° CA) as shown in the following equation (3). Change the retardation amount θK.

θ to ← θ to −0,08° CA... (3) Also,
The learned retardation amount θKG according to engine conditions is calculated as follows. First, as shown in Fig. 1, addresses 0 to 23 for storing learning retard amounts in correspondence with engine speed N and load Q/N are prepared in the random access memory (RAM) of the microcomputer, and a learning map is created. Create. The engine speed N and intake air IAI Q are taken in, and the RAM address surrounding the point (h=u, 1...
...16).

n+1. h+g, IQ+7, and the learning delay angle θKG for the address! Learning retardation amount θxq(n+1) at address ny+1
.

Learning retardation amount θxa()1+6) at address h+6, address h+
It is assumed that the learning retardation amount θKG (, n+7) is also stored in 7. Then, the difference in engine speed between the addresses is X2. If the difference in load between the two points is y, then the learning retardation amount θKG of the point indicating the current engine condition can be determined by the two-dimensional interpolation method shown in equations (4) to (6) below.

Momme (θKG4-θKG (n+1) A=□+θKG, l'l...(4)φ(θKa
(n-44)-〇KG (n+7)B=□+θKG(n
(10) ... (5) The learning control of the learning map described above is performed as follows. First, a second timer that determines the learning control time depending on the current engine conditions and a third timer that determines the learning control time regardless of the engine conditions are prepared. A second timer is used for a predetermined period of time (for example, 48 m 5e
c) When it is detected that the time has elapsed, the correction retard angle 7i
It is determined whether or not eK has been changed to exceed a predetermined crank angle (for example, 40CA), and when the corrected retardation amount θK exceeds the predetermined crank angle, a point indicating the current engine condition explained above is enclosed. A predetermined crank angle (for example, 0.04° CA) is added to the learning retard amounts at the four points on the learning map.As a result, the learning retard amounts are learning-controlled so that the ignition timing is delayed.Meanwhile, the third timer for a predetermined time (for example, 16 seconds)
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 θK G obtained by two-dimensional interpolation from the learning map subjected to learning control, the above equation (1) is calculated. Based on this, the basic ignition advance angle θBASE is corrected to control knocking.

By the way, as shown in Fig. 3, the basic ignition advance angle Adva
nce F'or Be5t Torgue) changes like a curve C1 according to the engine speed. In addition, 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 C2, and when knocking is likely to occur, such as when the air is dry, minute knocking occurs. The ignition timing is as shown by curve C3. Therefore, the ignition timing at which minute knocking occurs varies depending on the engine speed and environmental conditions.

Therefore, in the above-mentioned knocking control method using learning control, all the learning retard amounts are independently changed to the advance side by learning control after a predetermined period of time has elapsed, regardless of the presence or absence of knocking. Under engine conditions where there are few opportunities for side learning control, the learning retard angle number becomes too advanced, resulting in the problem of knocking. Also,
As mentioned above, since the amount of learning retardation tends to be controlled to the advanced side, the learning control speed for controlling the ignition timing to the advanced side cannot be set quickly, as shown in Fig. 3 above. When engine conditions change and knocking becomes less likely to occur, the ignition timing may be retarded too much due to the learned retardation amount, and knocking does not occur (the best torque cannot be obtained in the region where knocking occurs). There was a problem with it being ugly.

Here, in order to solve the above problem, it is possible to perform learning control on all the learning retard numbers so that the corrected retard amount falls within a predetermined range11, but the corrected retard amount in the light load range Learning control is performed so that the amount of learning retardation is reduced in a region where is less than a predetermined value, and the learning retardation l on the light load side that is learned when the engine condition is in a high load range is also learned to be reduced. Therefore, a problem arises in that knocking occurs when the load slightly increases beyond the range where the corrected retard amount is equal to or less than a predetermined value.

The present invention was made to solve the above-mentioned problems, and the learning retardation amount is not disturbed even when the engine is operated in a light load range, and knocking does not occur even if the load increases slightly from the static load range. It is an object of the present invention to provide a knocking control method.

In order to achieve the above object, the configuration of the present invention is based on a basic ignition advance angle determined by the engine speed and load, and a learning control that determines the knocking level based on the engine speed and load in order to bring the knocking level to a predetermined level. Subtract the sum of the learning retard number changed by and the corrected retard amount that retards the ignition timing when knocking occurs and advances the ignition timing when knocking no longer occurs, and determines that the corrected retard amount is within a predetermined range. A knocking control method for an internal combustion engine, in which the learning control method of the internal combustion engine controls knocking by learning-controlling the learning retardation amount so that the learning retardation amount reaches a value of The specific learning delay angle number on the light load side is set to a constant value.

According to the configuration of the present invention, the learning control is stopped within a specific region on the light load side, and the number of learning retard angles on the light load side within this specific region is kept constant, so that the engine condition exists within the specific region. Optimal knock control can be maintained without destroying the learned retard angle number on the high load side even when the load is increased, reducing the occurrence of knocking when the load increases from light load. A unique effect can be obtained in that the ignition timing changes smoothly.

Next, FIG. 4 shows an example of an engine to which the present invention is applied. As shown in the figure, this engine is equipped with a near 70-meter 2 as an intake air amount sensor provided downstream of an air cleaner (not shown). The air flow meter 2 includes a compensation plate 2A that is rotatably provided in a damping chamber, and a potentiometer 2B that detects the opening degree of the convention plate 2A. Therefore, the intake air IQ is detected as the voltage output from the potentiometer 2B. Further, an intake air temperature sensor 4 is provided near the air meter 2 to detect the temperature of intake air.

A throttle valve 6 is arranged downstream of the air throw 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 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 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 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. The reference position signal is output to the electronic city 1 control circuit 34.

The electronic control circuit 34, as shown in FIG.
Access Memo'J (RAM) 36, Read Only Memory (ROM) 38, and Central Processing Unit (C
PU) 40, a clock (CLOCK) 41, a first input/output boat 42, a second input/output boat 44, and a first input/output boat 44.
and a second output port 48, and the RAM 36. ROM38. CPU40. C.L.
The OCK 41, the first input/output port 42, the second input/output port 44, the first output port 46, and the second output port 48 are connected by a bus 50. The first input/output boat 42 includes a buffer (not shown), a multiplex V
Kusa 54. Analog-digital (A/D) converter 56
Through the air flow meter 2. Cooling 1 water temperature sensor 24
and intake air temperature riser 4 etc. are connected. The multiplexer 54 and A/D converter 56 are controlled by signals output from the first input/output port 42.

An Ox 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 rotor 4. ing.

In addition, the second input/output capo 44 includes a bandpass 7 filter 60. Peak hold circuit 61. Knocking sensor 18 is connected via channel switching circuit 66 and A/D converter 68. This band-pass filter is connected to a channel switching circuit 66 via an integrating circuit 63, and a second circuit for inputting either the output of the peak hold circuit 61 or the output of the integrating circuit 63 to an A/D converter 68. A control signal output from the human output boat 44 is input, and a reset signal is input from the second input/output boat 44 to the peak hold circuit 61.

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 device 12 via a drive circuit 72.

The ROM 3B of the electronic control circuit 34 stores in advance a map of the basic ignition advance angle θBABK expressed by the engine speed and intake air intake, the basic fuel injection amount, etc.
The basic ignition advance angle and the basic fuel injection amount are continuously output based on the signals from the air 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 output. In response to the signal, a corrected ignition advance angle and a corrected fuel injection number 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 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 only the knocking control routine related to the present invention will be explained. explain.

FIG. 6C shows an interrupt routine every 30° CA when the present invention is implemented using a microcomputer. First, in step 81, the engine rotation speed N is calculated from the rotation time based on the signal from the engine rotation angle sensor 32, and in step 82, the number of interruptions is counted after the cylinder discrimination signal is input from the air pressure discrimination sensor 30. to set a flag indicating the current crank angle. Next, step 8
3, the flag set in step 82 is at top dead center (T
DC) flag. 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 switched to a pantone filter. ri60,
A via the integral M path 63 and the channel switching circuit 66
A/D converter 68 starts A/D conversion of the average engine vibration value, that is, the background level. Subsequently, in step 87, the closing side t1 of the knock gate is
That is, the next time to close the knock gate is calculated and 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 9000A BTDC (before top dead center). Crank angle is 90°C
A If it is not BTDC, proceed to step 91,
When it is CA BTDC, the corrected advance angle is updated to θ in step 89, and the ignition timing is calculated (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 one engine vibration, and when the time set in step 87 of 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 then returned to the main circuit.

FIG. 8 shows the routine of time coincidence interrupt B, and when the time set in step 90 and step 92 of FIG. 6 comes, an interrupt 752 is performed. Step 9
In step 4, it is determined whether the igniter on flag is set, that is, whether this flag is 1 force λ or not, and if the flag is set, step.

The igniter is turned on in step 96, and when the flag is off, the igniter is turned off in step 95 and the process returns to the main routine.

FIG. 9 shows the A/D conversion completion interrupt routine, in which the A/D conversion of the background level and the A/D conversion of the peak hold value (this interrupt is performed when the A/D conversion 73 (of the peak hold value) is completed. First, step In step 97, it is determined whether or not the knock gate is currently open.If the knock gate is closed, the sixth
Diagram steps.

The A/D conversion value converted in step 86 is stored in the memory of RAM 36 and set as background level b.
At 9, the knock gate is opened and the process returns to the main routine. On the other hand, when the knock gate crab is open, the A/D conversion value converted in step 93 of FIG.
The memory K1 of M36 is stored as the peak value a, and in step 101, the knock 'y'-) is closed and the process returns to the main routine.

FIG. 10 shows an interrupt routine that is performed every predetermined time (for example, 4 m5 ec) for counting the time when no knocking occurs and the time for learning control. First, in step 102, the count value of the counter TIMEI, which determines the time when no knocking occurs, is increased by 1, and in step 103, the count value of the counter TIMFJ2, which determines the time for learning control, is increased by 1. In the next step 104, the count value of the counter TIMEI is 12 (48m8ee).
Determine whether the following is true or not. Count value is 12
If the count value exceeds 12, the count value of the counter TIMEL is set to 12 in step 105.
In the following cases, the counter TIM is entered in step 106.
It is determined whether the count value of E2 is 12 or less. Here, if the count value exceeds 12, the process proceeds to step 107, and if the counter TIME20 count value is 12 or less, the process returns to the main routine.

Next, the detailed routine of step 89 in FIG. 6 will be explained based on FIG. 11. When it is determined in step 88 of FIG. 6 that the crank angle has reached 90° CA BTDC, the load Q/N is determined to be 0.6 C1/r in step 122.
e It is determined whether or not it is v3 or higher, that is, whether or not it is in the knocking control region. If it is not in the knocking control region, in step 123, the basic ignition advance angle θBASE is changed to the ignition advance angle θi.
g and 1. Step when in knock control area. 10
8, the peak value a stored in step 100 of FIG. 9 is compared with a value Kb 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 Kb, it is determined that knocking has occurred, and in step 11O, the correction retard amount θK is increased by a predetermined angle (for example, 0.4° CCA), and in step 112, the time during which knocking does not occur is determined. Clear the count value of the counter TIMEI. On the other hand, when the peak value a is less than or equal to the value Kb, it is determined that knocking will not occur, and in step 109, the counter T I M J! It is determined whether the count value of E1 is greater than or equal to a predetermined value (12), and if the count value is greater than or equal to the predetermined value, it means that a state in which no knocking occurs has continued for a predetermined period of time, so step 11
1, the correction retard amount θK is set to a predetermined angle (for example, 0.08°
CA) After decrementing, in step 112 the counter T I
Clear M E 1. 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 advance angle is calculated using the corrected advance/retardation θ obtained as described above and the learned retard point needle θKG obtained from the learning map by the two-dimensional interpolation method, as shown in the above-mentioned equation (1). θBAliB is corrected to calculate the ignition advance angle θig that actually controls the igniter.

A routine for determining the learning advance angle amount θKG corresponding to the current engine condition from the following learning map and performing learning control will be explained. FIG. 12 shows this routine from the middle of the main routine. In addition, 6.7, 8, and 6.7, 8 of the learning map shown in Figure 1
14. ] Learning control is not performed for addresses 5, 16° and 17.

First, in step 124, the load Q/N is 0.6 (1
/ r ev ) or more, that is, whether or not it is in the knocking control region. If it is not in the knocking control region, continue directly to the main routine. If it is in the knocking control region, in step 114, the four points in the RAM surrounding the point indicating the current engine condition determined by the engine speed N and the load Q/N are stored. Find the street address on the learning map. Next, in step 115 h, the obtained four points of RAM
The data stored at the address, that is, the 4 points of RA
Using the two-dimensional interpolation method (the routine of the two-dimensional interpolation method will be explained later) based on the before learning delay angle stored at the address M,
A learning advance angle amount θKG at a point indicating the current engine condition is calculated, and the calculated value is stored in a predetermined location in the RAM.

In the next step 125, the engine speed iI is set to 300.
0 (rpm) or less, and if the engine rotation speed is 3000 [rpm] or less, step 12
Step 6 determines whether the load Q/N is 0.8 (f/rev) or more, and if the engine speed exceeds 3000 (rpm), step 12!?, determines whether the load Q/N is 1.
．． o(//Determine whether it is less than rev3. Step 1
26, when the load is 0.8 (1/re v ) or more, the process proceeds to the next step 116, and the load is 0.8 C1/
r e v), the process proceeds to the next routine. Further, if the load is 1.0 (J/rev) or more in step 127, the process proceeds to the next step 116, and if the load is less than 1.0, the process proceeds to the next routine. As a result, 6.7, 8, 14, 15, 16, 17 of the learning map shown in Fig.
If a point indicating the engine condition exists within a specific area below the line connecting the addresses, learning control is not performed, and only in step 116 if a point indicating the engine condition exists within the area excluding this specific area. The learning control shown in step 121 is then performed.

In step 116, the counter TI is used to obtain the learning control time counted in step 103 in FIG.
It is determined whether the count value of ME2 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 counter values of counter T and IME2 are cleared in step 117, and then step 110 in FIG. Then, in step 118, it is determined whether the corrected retardation amount θK updated in step 111 is greater than or equal to a first predetermined crank angle (for example, 2° CA).

If it is determined in step 118 that the corrected retardation amount OK is less than the first predetermined crank angle, then in step 121 the learning information stored in the four points on the learning map surrounding the point indicating the current engine condition is determined. Learning control is performed to subtract a predetermined crank angle (for example, 0.04 CA) from each retard amount, and the process returns to the main routine. As a result, when the corrected advance angle θK is less than the first predetermined crank angle, learning control is performed so that the learning retardation value of the learning map becomes smaller, and the ignition timing is controlled to advance by the learning retardation value. On the other hand, if it is determined in step 118 that the corrected retard angle θK is greater than or equal to the first predetermined crank angle, then in step 119 the corrected retard angle lθK is set to a second predetermined value larger than the first predetermined crank angle. Crank angle (e.g. 4'C)
A) Determine whether it is less than or not. 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 eK satisfies the following conditions, the first predetermined crank angle (2° CA) ≦θ 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 is not changed by the learning retard. 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°C) to the learning retard stage stored at the four points on the learning map surrounding the point indicating the current engine condition, and the main Return to routine.

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

By performing the learning control as described above, the learning retardation experience 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 1150 of FIG. 12. In this two-dimensional interpolation routine, the map shown in Fig. 1 is used as a learning map, and the four RAM addresses representing the current engine conditions are determined as n, n + 1, and n + 1 as shown in Fig. 2.
Let m + 6 and 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 (1/rev3).
), the step knob 131 stores 1.2 in the V distal, and the load is 1°, 2(l/re
v] or less, the current value of load Q/H is stored in register n in step 134.

In step 135, the current engine speed N is determined to be the upper limit of the engine speed on the learning map, that is, 6000 (
rpm) or less.

If the engine speed exceeds 6000 (rpm), 6000 is stored in register m in step 136, and if the engine speed is 6000 (rpm) [F, the current engine speed is stored in step 137. Store the value of N in register m. In step 138, the value of register n is set to the lower limit of the load on the learning machine, that is, 0.6.
C1/r e v) or more, and if the value of register n is less than 0.6, step 13
In step 9, the value of register n is set to 0.6, and if the value of V distal is 0.6 or more, the process proceeds to step 140.

Then, in step 140, the value of V register m is set to the lower limit of engine speed on the learning map, that is, 100'0 (
It is determined whether the rpm is 3 or more, and if the value of register m is less than 1000, in step 141 V
The value of register m is 1000, and the value of register m is 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 n, respectively, and the current engine speed N and load Q/N are on the learning map. When the upper and lower limit values are exceeded, the upper and lower limit values are stored in registers m and nK, 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 at address 0 (0.6 C1/r e v) from the value of register n is stored in register n. Next, in step 143, the value of register n is set to 0, 2, which is the load scale interval.
The integer part of the quotient is stored in register n, and the remainder of the quotient is stored in register y. The value of this register y is 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, for example, addresses O to 5). The first column is the first column). Then, in step 144, the value of register y is further divided by 0.2 C1/r e vl. Therefore, in the end, register y contains y/ of equation (6) above.
A value corresponding to Y is stored.

In step 145, the value of the engine rotation speed at address 0 is changed from the value of register m to 101000 (1(r
The value obtained by subtracting p is stored in register m. Next, in step 146, the value in register m is divided by 1000 [rpm], which is the scale interval of engine rotational speed, and 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 For example, 0°6.12.
18 is the first row).

Then, in step 147, the value of register X is further divided by 1000 (rpm). Therefore, finally, in register X, x /
A value corresponding to X is stored.

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 angle θKGHi stored at address n on the learning map is read out from the register A.
The learning delay angle θ stored at address n+1
KG (n+1) is read and stored in register B, and n
Learning retardation amount θKG stored at address +6 (n+6
) is read out and stored in V register C, and the learned retard amount θKc(n-)-7) stored in address n+7 is read out and stored in register D. Next, step (5)
), the value of register B is subtracted from the value of register A, the value of telesistor X is multiplied, and the value of register A is added to this value, and the result is stored in register E. Further, in step 152, the value of register D is subtracted from the value of register C, the value of register X is multiplied by L, and the value of register C is added to the value of t to F, and the value of register C is stored in the register F. Finally, in step 153, the value of V 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 obtain a point indicating the current engine condition. Let the learning retard amount θKG be.

Learning retardation amount θK in the learning routine shown in FIG. 12 above
The following table summarizes the relationship between the conditions for the corrected retard amount θ when G is updated by learning control and the increase/decrease in the learned retard amount θKG.

Further, FIG. 14 shows changes in the corrected retard amount θK, learned retard angle θKG, and ignition timing O1g over time. As can be understood from the figure, when the corrected retard amount θK is within a predetermined range, the learned retard amount &xa is constant, and the corrected retard amount θK
When θK exceeds a predetermined range, the learned retard amount θKG increases, and when the corrected retard amount θK falls below a predetermined range, it decreases.

Furthermore, FIG. 15 shows variations in ignition timing corresponding to engine speed. In Fig. 15, the curves C1 to C8 are the same as those in Fig. 3, and it is understood that the corrected retardation amount θK is always constant regardless of whether knocking is likely to occur or when knocking is unlikely to occur. be done.

After the above-described learning control routine is performed, a Nissl routine for keeping the learning retard amount constant at a specific address on the light load side shown in FIG. 16 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, addresses of specific RAMs below a predetermined load on the light load side on the learning map shown in FIG. ,4゜5.
9, 10, and 11) is rewritten to a predetermined crank angle (for example, O'CA).

By setting the specific learned retard amount on the light load side to a constant value as described above, the required retard amount (+θKG for θ) from the basic ignition advance angle for the load Q/'H has the characteristics shown in Fig. 17. becomes. Figure 17 shows the engine speed is 2000 [rpm].
), 4000 (which shows the characteristics of rpml,
On the light load side, the ignition timing at which knocking occurs is more advanced than the basic ignition advance angle, and the learning retardation amount is 0°CA.
It is understood that since the value is set to a constant value, the required retardation amount is 0° CA, and the rise of the retardation amount is smooth.

Further, FIG. 18 shows the relationship between the load and the amount of retardation.

As shown in the figure, load 0.8 C1/ r e 'V1
It is understood that the learning retardation amount is approximately constant in the following light load range.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the learning map, Figure 2 is an explanatory diagram showing a point indicating the current engine condition and the four points surrounding this point, and Figure 3 is a line indicating the relationship between engine speed and ignition timing. 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 4m sec, 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 two-dimensional interpolation routine. Flowchart, Fig. 14 is a diagram showing changes in corrected retardation, learned retard number, and ignition timing over time; Fig. 15 is a graph showing the relationship between engine speed and ignition timing, similar to Fig. 3; corrected retardation A diagram showing the following relationship between the learning delay angle and the learning delay angle, Fig. 16 is 3.
2...Engine rotation angle sensor. 34...Electronic control circuit. Agent Tatsuyuki Unuma. ((1 force, 2 threads) Fig. 1 Fig. 2 Fig. 3 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 11 Fig. 12 Fig. 14 Fig. B = 1 sec] Figure 15, Figure 16

Claims (2)

[Claims] (1) Determined by engine speed and load -
From the basic ignition advance angle, when knocking occurs, the ignition timing is delayed and the learning retardation amount is determined depending on the engine speed and load and changed by learning control in order to bring the knocking level to a predetermined level. An internal combustion engine that controls knocking by subtracting the sum with a corrected retard amount that advances the ignition timing when knocking no longer occurs, and performs learning control on a learned retard amount so that the corrected retard amount falls within a predetermined range. The knocking control method is characterized in that the learning control of the learning retardation amount in a specific area including light loads is stopped, and the specific learning retardation noise on the light load side in the specific area is set to a constant value. A knocking control method for an internal combustion engine. (2) A knocking control method for an internal combustion engine according to claim 1, wherein the certain value is zero.