JPH0646024B2 - Knotting control method for internal combustion engine - Google Patents

Description

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

A conventional knocking control method based on learning control uses a ratio Q / of engine speed N, intake air amount Q and engine speed N /
The basic ignition advance angle θ _BASE, which is determined in advance by the load determined by N or the intake pipe negative pressure, is stored in the form of a map in the read-only memory (ROM) of the microcomputer, and is actually calculated based on the following equation (1). The ignition advance angle θig for controlling the igniter is calculated, and the knocking control is performed using this ignition advance angle.

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

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

θ _K ← θ _K + 0.4 ° C. A (2) When the peak value a is equal to or less than the judgment level K · b, it is judged that no knocking has occurred, and the first timer is used to set the predetermined value. It is determined whether or not a time (for example, 48 msec) has elapsed, and when a predetermined time has elapsed, a predetermined crank angle (for example, 0.08 ° A) ignition timing advance amount is advanced as shown in the following equation (3). Change θ _K.

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

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

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

In addition, in the above-described knocking control method, when an abnormality such as disconnection, sensor deterioration, contact failure, and electrical noise superimposed on the signal line occurs in the knocking sensor and the signal line, the knocking is detected. I can't
The electric signal above the judgment level is not output even though the engine is knocking, or the electric signal above the judgment level is output despite that the engine is not knocking. Especially, if it is judged that there is no knocking in spite of occurrence of knocking,
The ignition timing advances to the most advanced state, the engine causes severe knocking and plague, and in the worst case, the spark plug and the piston are melted and the engine is destroyed, such as the blowout of the gasket. There was a problem of being lost.

In order to solve such a problem, conventionally, the back ground level of the electric signal output from the knocking sensor is obtained, and the routine shown in FIG. 3 detects whether the knocking sensor or the like is abnormal. That is, in step S1, the engine speed is a predetermined value (for example, 2000 [r.p.
m]) or more, and in step S2, the background level b is a predetermined value b ₀ (for example, 100 [m
v]) It is determined whether or not the following. If the state in which the engine speed is equal to or higher than the predetermined value and the background level b is equal to or higher than the predetermined value has continued for the predetermined time (step S5), it is determined that the knocking sensor or the like is abnormal, and in step S6. It was detected by setting the notking sensor abnormality flag F _KF . As a result, it is possible to detect abnormality such as deterioration of the sensor and disconnection of the knocking sensor output.

The timer TIME3 in step S5 is a timer that increments the count value by 1 every predetermined time (for example, 4 msec), and the count value 12 in step S5 is 48 m.
represents sec. When the engine speed is less than the predetermined value, the routine directly proceeds to the next routine. When the engine speed is more than the predetermined value and the background level is less than the predetermined value, the counter TIME3 is cleared in the step S3 and the flag is set in the step S4. After lowering F _KF , the routine proceeds to the next routine, and when the engine speed is equal to or higher than the predetermined value, the background level is equal to or higher than the predetermined value, and the predetermined time has not elapsed, the routine directly proceeds to the next routine. FIG. 4 shows the knocking sensor output with respect to the engine speed, where A is the back ground level when no knocking occurs, and B is the noise level.

Then, when an abnormality such as the knocking sensor is detected as described above, in order to prevent the engine from being damaged, the engine is retarded to the ignition timing at which knocking does not occur for all engine operating conditions, and the fail safe is performed.

However, in the conventional knocking control method for performing learning control, the learning retard amount is learned and controlled in accordance with the magnitude of the corrected retard amount, so that the failing sensor returns to the normal state after failsafe is performed. The learning control causes a problem that the ignition timing is abnormally retarded, which causes a reduction in output and deterioration of fuel efficiency. As described in JP-A-56-47663, even if the ignition timing is simply retarded when the vibration sensor is abnormal, the ignition timing is immediately optimized when the vibration sensor returns to the normal state. It cannot be restored to a normal state.

An object of the present invention is to provide a knocking control method for an internal combustion engine that can immediately return the ignition timing to the optimum state when the vibration sensor returns from the abnormal state to the normal state.

In order to achieve the above-mentioned object, the structure of the first invention detects the occurrence of knocking by a vibration sensor that is sensitive to engine vibration, and knocks from the basic ignition advance determined by the engine speed and load. When the ignition timing is retarded and when the knocking does not occur, the ignition timing is set so as to advance the ignition timing and the knocking level is set to a predetermined level. Or a second predetermined value having an absolute value smaller than the absolute value of the first predetermined value, the sum is subtracted from the learning delay amount by which the value is rewritten,
In a knocking control method of an internal combustion engine for controlling knocking, when the vibration sensor output becomes abnormal, the learning retard amount is held without being changed, and the ignition timing is retarded to a predetermined maximum retarded state. To do. As a result,
The learning retard amount is held unchanged, and the ignition timing is retarded to the maximum retarded state that does not cause knocking under all engine operating conditions to perform fail-safe. According to the configuration of the first aspect of the present invention, the learning delay amount immediately before the abnormal state of the knocking sensor output can be used when the normal state is restored after the abnormal state of the knocking sensor output. A unique effect is obtained in that the knocking control can be performed by various learning controls.

In order to solve the above-mentioned problem, in the configuration of the second invention, the presence or absence of knocking is detected by the vibration sensor that is sensitive to the vibration of the engine, and the knocking is generated from the basic ignition advance angle determined by the engine speed and the load. When the ignition timing is retarded and when the knocking does not occur, the ignition timing is set so as to advance the ignition timing and the knocking level is set to a predetermined level. Or a second predetermined value having an absolute value smaller than the absolute value of the first predetermined value, the sum is subtracted from the learning delay amount by which the value is rewritten,
In a knocking control method of an internal combustion engine for controlling knocking, when the vibration sensor output becomes abnormal, the learning retard amount is held without being changed, and the learning retard amount is determined from a predetermined maximum retard amount. The value obtained by subtracting is used as the correction delay amount. As a result, the learning retard amount is maintained without being changed, and the learning retard amount is maximally retarded using the corrected retard amount that is changed at a relatively fast speed. Therefore, the second
According to the configuration of the invention, when the knotting sensor output becomes abnormal and then returns to the normal state, the delay amount is quickly controlled to the normal retard amount, the decrease in the output is reduced, and the fuel consumption at the time of returning to the normal state is reduced. It is possible to obtain a peculiar effect that is improved.

Further, in the configuration of the third invention, the presence or absence of knocking is detected by the vibration sensor sensitive to the vibration of the engine, and from the basic ignition advance angle determined by the engine speed and the load,
The ignition timing is retarded when knocking occurs and is advanced to advance the ignition timing when knocking does not occur. The knock is controlled by subtracting the sum of the first predetermined value or the second predetermined value having an absolute value smaller than the first predetermined value and the learning retard amount that is rewritten by the control. In the knocking control method for an internal combustion engine, when the vibration sensor output becomes abnormal, the learned retard amount is held without being changed and the corrected retard amount is set to a predetermined value, from the basic ignition advance, A value obtained by subtracting a predetermined maximum retardation amount is used as the ignition advance angle for ignition. According to this configuration, when the output of the knocking sensor becomes abnormal, the learning delay amount is held without being changed and the correction delay amount is set to the predetermined value, so that the output of the knocking sensor is changed again. When the normal state is restored, the optimum ignition advance angle is immediately obtained, and the output and fuel efficiency are improved, which is a unique effect.

By the way, the basic ignition advance angle θ _BASE, that is, MBT (Minimu
As shown in Fig. 5, m Spamk Advarce For Best Torque) changes according to the engine speed as shown by curve C ₁ , and is a minute knocking when knocking is difficult to occur when the air is wet. The generated ignition timing is as shown by the curve C ₂ , and the minute knocking generated ignition timing when the knocking is likely to occur such as when the air is dry is the curve C 2.
It becomes like ₃ . Therefore, in order to always perform the same knocking control under the condition that the knocking is likely to occur and the condition where the knocking is unlikely to occur, in the above-described configuration of the present invention, the corrected ignition advance angle is in the predetermined range (for example, 2 ° C. A ≦ θ _K ≦ 4 ° C
It is preferable to perform learning control of the learning retard amount so as to be A).

Further, in the above-described configuration of the present invention, it is preferable to retard the ignition timing and simultaneously reduce the air fuel consumption of the air-fuel mixture when the output of the knocking sensor is abnormal. By doing so, the exhaust gas temperature decreases, so that the actual retard amount can be brought close to the theoretical value.

Next, FIG. 6 shows an example of an engine to which the present invention is applied. This engine is controlled by an electronic control circuit such as a micro computer, and as shown in the figure, an air flow meter 2 as an intake air amount sensor is provided downstream of an air cleaner (not shown). The air flow meter 2 is composed of a compensation plate 2A that is rotatably provided in the dipping chamber, and a potentiometer 2B that detects the opening of the compensation plate 2A. Therefore, the intake air amount is detected from the voltage output from the potentiometer 2B. Also,
An intake air temperature sensor 4 that detects the temperature of intake air is provided near the air flow meter 2.

A throttle valve 6 is arranged downstream of the air flow meter 2, and a surge tank 8 is provided downstream of the throttle valve 6.
Is provided. An intake manifold 10 is connected to the surge tank 8, and a fuel injection valve 12 is arranged so as to project into the intake manifold 10. The intake manifold 10 is connected to the combustion chamber 14A of the engine body 14 and is connected to the combustion chamber 1 of the engine.
4A is connected via an exhaust manifold 16 to a catalytic converter (not shown) filled with a three-way catalyst. The engine body 14A is provided with a knocking sensor 18, which is composed of a microphone and detects the vibration of the engine due to combustion. Reference numeral 20 is an ignition plug, 22 is an O ₂ sensor for making the air-fuel mixture near the stoichiometric air-fuel ratio by feed back control, and 24 is a cooling water temperature sensor for detecting the engine cooling water temperature.

The spark plug 20 attached to the engine main body 14 is connected to a distributor 26, and the distributor 26 is connected to an igniter 28. The distributor 26 is provided with a cylinder discriminating sensor 30 and an engine rotation angle sensor 32, each of which is composed of a pick-up fixed to the distributor housing and a signal rotor fixed to the distributor shaft. . The cylinder discriminating sensor 30 outputs a cylinder discriminating signal to an electronic control circuit 34 composed of a microcomputer or the like for each crank angle of 720 degrees, and the engine rotation angle sensor 32 outputs a crank angle reference for each crank angle of 30 degrees. The position signal is output to the electronic control circuit 34.

As shown in FIG. 7, the electronic control circuit 34 includes a random access memory (RAM) 36, a read only memory (ROM) 38, a central processing unit (CPU) 40, a clock (CLOCK) 41, and a first memory. I / O port 42,
A RAM 36, which is configured to include a second input / output port 44, a first output port 46 and a second output port 48.
The ROM 38, the CPU 40, the CLOCK 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 such as a data bus or a control bus. There is.

The first input / output port 42 has a buffer (not shown),
Multiplexer 54, analog-digital (A / D)
The air flow meter 2, the cooling water temperature sensor 24, the intake air temperature sensor 4, and the like are connected via the converter 56. The multiplexer 54 and the A / D converter 56 have a first
It is controlled by a control signal output from the input / output port 42. The O ₂ sensor 22 is connected to the second input / output port 44 via a buffer (not shown) and a comparator 62.
Are connected, and the cylinder discrimination sensor 30 and the engine rotation angle sensor 32 are connected via a waveform shaping circuit 64. The second input / output port 44 is connected to the knocking sensor 18 via a band pass filter 60, a peak hold circuit 61, a channel switching circuit 66 and an A / D converter 68. This bandpass filter is connected to a channel switching circuit 66 via an integrating circuit 63. A control signal for inputting one of the output of the peak hold circuit 61 and the output of the integration circuit 63 to the A / D converter 68 is input to the channel switching circuit 66 from the second input / output port 44. The reset signal and the gate signal are input to the peak hold circuit 61 from the second input / output port 44.

Further, the first output port 46 is connected to the igniter 28 via the drive circuit 70, and the second output port 48 is connected to the fuel injection valve 12 via the drive circuit 72.

In the ROM 38 of the electronic control circuit 34, the basic ignition advance map and the basic fuel injection amount, which are represented by the engine speed and the intake air amount (or load), are stored in advance.
The basic ignition advance angle and the basic fuel injection amount are read based on the signal input from the air flow meter 2 and the signal input from the engine rotation angle sensor 32, and the signals from the cooling water temperature sensor 24 and the intake air temperature sensor 4 are read. By various signals including, the corrected ignition retard amount and the corrected fuel injection amount are added to the basic ignition advance and the basic fuel injection charge, and the igniter 28 and the fuel injection valve 12 are controlled. The air-fuel ratio signal output from the O ₂ sensor 22 is used for air-fuel ratio control that controls the air-fuel ratio of the air-fuel mixture to near the stoichiometric air-fuel ratio.

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

FIG. 8 shows an interrupt routine for every 30 ° C. when the present invention is carried out by using a microcomputer. First,
At step 81, the engine speed N is obtained from the rotation time based on the signal from the engine rotation angle sensor 32. At step 82, the number of interrupts after the cylinder discrimination signal is input from the cylinder discrimination sensor 30 is counted and the current interrupt is counted. Set a flag that indicates the crank angle. Next, at step 83, the flag set at step 82 is set to the top dead center (TD
It is determined whether the flag is C). When it is not the top dead center at present, the routine proceeds to step 88, and when it is now the top dead center, it is judged at step 84 whether or not the knock gate is closed. When the knock gate is open, the knock gate is closed at step 85, and when the knock gate is closed, the channel switching circuit 66 is switched at step 86, and the engine vibration signal output from the knocking sensor 18 is integrated by the band pass filter 60 and integrated. A / D via circuit 63 and channel switching circuit 66
It is input to the converter 68, and the average value of the engine vibration, that is, the A / D conversion of the background level is started. Then, at step 87, the closing time t ₁ of the knock gate,
That is, next, the time at which the knock gate is closed is calculated, and the time coincidence interrupt A is set.

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

Next, the time coincidence interrupt A shown in FIG. 9 will be described.
This interrupt routine is for obtaining the peak value of the engine vibration. When the time set in step 87 of FIG. 8 is reached, an interrupt is made, and the peak value held in the peak hold circuit 61 is transferred to the channel switching circuit in step 93. The peak hold value is input to the A / D converter 68 via 66 to start the A / D conversion of the peak hold value, and the process returns to the main routine.

FIG. 10 shows a routine of the time coincidence interrupt B. When the time set in step 90 and step 92 in FIG. Step 94
Then, it is determined whether the igniter on flag is set, that is, whether this flag is 1 or not. When the flag is set, the igniter is turned on in step 96, and when the flag is set, the igniter is turned off in step 95. And then returns to the main routine.

FIG. 11 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 or not the knock gate is currently open. When the knock gate is closed, in step 98 the A / D conversion value converted in step 86 of FIG. 8 is stored in the memory of the RAM 36 and set to the back ground level b. In step 99, the knock gate is opened and the main routine is returned. To do. On the other hand, when the knock gate is open, the A / D conversion value converted in step 93 of FIG.
The peak value a is stored in the memory of the AM 36, the knock gate is closed in step 101, and the process returns to the main routine.

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

Next, the detailed routine of step 89 in FIG. 8 will be described with reference to FIG. If it is determined in step 88 of FIG. 8 that the crank angle has reached 90 ° C. BTDC, step 122 determines whether it is in the knocking control region, and if it is not in the knocking control region, ignition advance angle θ _ig is determined in step 123. _Is set to the value of the basic ignition advance angle θ _BASE , and the routine proceeds to the next routine. On the other hand, in the knocking control area, in step 108, the peak level a stored in step 100 of FIG. 11 and the back ground level b stored in step 98 of FIG. 11 are multiplied by a constant K.・ Compare with b. When the peak value a exceeds the determination level K · b, it is determined that knocking has occurred, the correction retard angle θ _K is increased by a predetermined angle (for example, 0.4 ° C. A) in step 110, and the knocking is detected in step 112. The count value of the counter TIME1 that counts the time that does not occur is cleared. On the other hand, when the peak value a is equal to or lower than the determination level K · b, it is determined that the knocking does not occur, and in step 109, the counter T
It is determined whether or not the count value of IME1 is equal to or more than a predetermined value (12). When the count value is equal to or more than the predetermined value, the state in which no knocking occurs continues for a predetermined time. Delay angle θ
_{After K} is decreased by a predetermined angle (for example, 0.08 ° C. A), the counter TIME1 is cleared at step 112. Also,
When the count value is less than the predetermined value in step 109, the process proceeds to step 113. In step 113, the corrected retard amount θ _K obtained as described above and the learned retard amount θ obtained by the two-dimensional interpolation method from the learned map.
_KG is used to correct the basic ignition advance angle θ _BASE as shown in equation (1), and the ignition advance angle θ _ig that actually controls the igniter is calculated.

Next, a routine for obtaining the learning retard amount θ _KG corresponding to the current engine condition from the learning map and performing learning control will be described. FIG. 14 shows this routine from the middle of the main routine.

First, in step 124, it is judged whether or not it is in the knocking control region, and if it is in the knocking control region, step 11
4, 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 obtained on the learning map. Next, at step 115,
Based on the data stored in the obtained four-point RAM addresses, that is, the learning retard amount stored in the four-point RAM addresses, the above equations (4), (5) and (6) are used. Two-dimensional interpolation calculation is performed to calculate the learning retard amount θ _KG at the point indicating the current engine condition, and the calculated value is stored in a predetermined location of RAM. At step 116, a counter TIM for obtaining the learning control time counted at step 103 in FIG.
It is determined whether the count value of E2 is a predetermined value (for example, 12) or more. When the count value is less than the predetermined value, the process returns to the main routine, and when the count value is the predetermined value or more, the count value of the counter TIME2 is cleared in step 117, and then the steps 110 and 1 in FIG.
In step 118, it is determined whether the corrected retard angle amount θ _K updated in 11 is equal to or larger than the first predetermined crank angle (for example, 2 ° C. A).
To judge.

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

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

Learning delay amount θ _KG in the learning routine shown in FIG.
The following table collectively shows the relationship between the correction retard angle amount θ _K and the increase / decrease of the learning retard angle amount θ _KG when updating is performed by learning control.

Further, FIG. 15 shows changes in the corrected retard amount θ _K , the learned retard amount θ _KG , and the ignition timing θ _{ig over} time. As can be seen, the retard amount theta _KG learning when the correction retard amount theta _K value of the predetermined range is constant, the retard amount learning when the delay correction amount theta _K exceeds the predetermined range theta _KG increases, and decreases when the corrected retard angle θ _K is less than the predetermined range.

Further, FIG. 16 shows the variation of the ignition timing corresponding to the engine speed. In FIG. 16, the curves C _{1 to} C ₃ are the same as those in FIG. 5, and the correction delay angle amount θ _K is always constant regardless of whether knocking is likely to occur or not. To be understood.

Next, the relationship between the learning control and the notking sensor output abnormality determination in the present invention will be described using the main routine of FIG. In step 140, the load Q / N is 0.6 [/
rev] or more, that is, whether the learning map is in the knocking control region or not. When it is not in the knocking control area, the routine proceeds to the next routine, and when it is in the knocking control area, it is judged whether or not the knocking sensor output abnormality flag F _KF obtained in the routine of FIG. 3 is down (step 14).
1). When the flag F _KF is down, that is, when the output of the knocking sensor is normal, in steps 142 to 144, the learning delay amount of the point indicating the current engine condition is obtained from the learning map by the two-dimensional interpolation method. After the elapse of a predetermined time, the learning control described above is performed, and the routine proceeds to the next routine. On the other hand, when the flag F _KF is set, it is held without learning control, that is, without changing the learning delay amount of the learning map, and the routine proceeds to the next routine.

FIG. 18 shows an interrupt routine of an embodiment of the second invention for controlling the ignition timing to the maximum retarded state by changing the correction retarded amount. This interrupt routine is performed every predetermined crank angle (for example, 90 ° C BTDC). First, in step 150, it is determined whether or not it is in the knocking control region, and in step 151, it is determined whether or not the flag F _KF is down. If the flag F _KF is in the knocking control region and the flag F _KF is down, the correction retard angle amount θ _K is updated according to the presence or absence of knocking in step 152, and step 1
At 54, the ignition advance angle θ _ig is calculated based on the basic ignition advance angle θ _BASE , the learning retard angle amount θ _KG, and the corrected retard angle amount θ _K, and the routine proceeds to the next routine. When the flag F _KF is set in the knocking control region, the learning retardation amount θ _KG stored and retained at the time when the knocking sensor output is abnormal from the maximum retardation amount (for example, 10 ° C. A) stored in advance in step 153. The value obtained by subtracting is taken as the value of the correction retardation amount θ _K , and the routine proceeds to step 154. As a result, ignition is performed with an ignition advance angle obtained by subtracting the maximum retardation amount from the basic ignition advance angle θ _BASE . If it is not in the knocking control region, the value of the basic ignition advance angle θ _BASE is set to the value of the ignition advance angle θ _ig in step 155, and the routine proceeds to the next routine.

In the above embodiment, the correction retard amount, which is retarded more quickly than the learning retard amount, is changed to obtain the most retarded state of the ignition timing. Therefore, when the knocking sensor output returns to the normal state, The retard amount from the ignition advance amount quickly becomes the optimum value.

FIG. 19 shows an interrupt routine of an embodiment of the third invention for setting the correction retard amount to a predetermined value when the knocking sensor is abnormal. This interrupt routine is performed every predetermined crank angle (for example, 90 ° C BTDC). The first
In FIG. 9, parts corresponding to those in FIG. 18 are designated by the same reference numerals, and description thereof will be omitted. If the output of the knocking sensor is abnormal in the knocking control region, the correction retard angle amount θ _K is set to a predetermined value (for example, 3 ° C. A) in step 160. The predetermined value of 3 ° C. in the present embodiment is a central value when the learning control is performed so that the correction retard amount becomes a value within a predetermined range (2 ° C. ≦ θ _K ≦ 4 ° C. A). In determining the value of this predetermined value, the ignition advance angle obtained by subtracting the sum of this predetermined value and the stored learning retard angle amount θ _KG from the basic ignition advance angle is such that advancement does not cause frequent knocking. It is preferable that the angular value is obtained. In the next step 161, the value obtained by subtracting the maximum retardation amount (for example, 10 ° C. A) from the basic ignition advance angle θ _{BASE is} set as the ignition advance angle θ _ig , and the routine proceeds to the next routine.
If it is not in the knocking control range, the basic ignition advance value is set to the ignition advance value, and the correction retard amount θ _K is set to a predetermined value (for example, 3 ° C. A) in step 162, and the routine proceeds to the next routine.

In the above embodiment, the correction retard angle amount is set to the center value of the correction retard angle amount variation range and the learning retard amount is held when the knocking sensor output is abnormal, so that the knocking sensor output can be normally obtained. A normal ignition timing is immediately obtained when

In the above description, the example in which the maximum retarded state of the ignition timing is obtained by the corrected retarded amount, the learned retarded amount, and the basic ignition advance has been described, but the ignition timing in the maximum retarded state is stored in advance. In advance, when the knocking sensor is abnormal, the retard may be retarded regardless of the correction retard amount, the learning retard amount, and the like.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a learning map, FIG. 2 is a diagram showing addresses surrounding the present engine conditions, FIG. 3 is a flow chart of a conventional knocking sensor output abnormality detection routine, and FIG. 4 is an engine. FIG. 5 is a diagram showing the relationship between the engine speed and the ignition timing, FIG. 5 is a diagram showing the relationship between the engine speed and the ignition timing, and FIG. 6 is a schematic diagram showing the engine to which the present invention is applied. FIG. 7 is a block diagram of the electronic control circuit in FIG. 6, FIG. 8 is a flow chart of an interrupt routine every 30 ° C.,
FIG. 9 is a flow chart of the time coincidence interrupt A, FIG. 10 is a flow chart of the time coincidence interrupt B, FIG. 11 is a flow chart of the A / D completion interruption routine, and FIG. 12 is a flow chart showing an interruption routine at predetermined time intervals. FIG. 13 is a flow chart of a routine for updating the correction delay amount, FIG. 14 is a flow chart of a learning routine, and FIG.
FIG. 16 is a diagram showing the retard amount and ignition timing with respect to the passage of time, FIG. 16 is a diagram showing the relationship between engine speed and ignition timing, and FIG. 17 is a flowchart showing the main routine of the present invention.
FIG. 18 is a flow chart showing an interrupt routine of the second invention,
FIG. 19 is a flowchart showing the interrupt routine of the third invention. 2 ... Air flow meter, 12 ... Fuel injection valve, 18 ...
… Notting sensor, 32 …… Engine rotation angle sensor,
34 ... Electronic control circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiyasu Ito 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Corporation (56) Reference JP-A-56-47663 (JP, A) JP-A-55-134731 (JP, A)

Claims (3)

[Claims] 1. A vibration sensor, which is sensitive to engine vibration, detects whether or not knocking has occurred, and delays the ignition timing when knocking occurs and prevents knocking from the basic ignition advance angle determined by the engine speed and load. When the ignition timing is set to advance the correction retard amount and the knocking level to a predetermined level, the magnitude of the correction retard amount is set to the first predetermined value or the first predetermined value by the learning control. In a knocking control method for an internal combustion engine, which controls knocking by subtracting a sum with a learning retardation amount that is rewritten when the second predetermined value has an absolute value smaller than the absolute value, the vibration sensor output is When the abnormality occurs, the learning retard amount is held without being changed, and the ignition timing is retarded to a predetermined maximum retarded state. Knocking control method for internal combustion engine. 2. A vibration sensor, which is sensitive to engine vibration, detects whether knocking has occurred, and delays the ignition timing when knocking occurs and prevents knocking from the basic ignition advance angle determined by the engine speed and load. When the ignition timing is set to advance the correction retard amount and the knocking level to a predetermined level, the magnitude of the correction retard amount is set to the first predetermined value or the first predetermined value by the learning control. In a knocking control method for an internal combustion engine, which controls knocking by subtracting a sum with a learning retardation amount that is rewritten when the second predetermined value has an absolute value smaller than the absolute value, the vibration sensor output is When there is an abnormality, the learning retard amount is held without being changed, and a value obtained by subtracting the learning retard amount from a predetermined maximum retard amount is set in advance. A knocking control method for an internal combustion engine, characterized in that the correction retard amount is set. 3. A vibration sensor that is sensitive to engine vibration is used to detect the occurrence of knocking, and from the basic ignition advance angle determined by the engine speed and load, the ignition timing is delayed when knocking occurs and knocking does not occur. When the ignition timing is set to advance the correction retard amount and the knocking level to a predetermined level, the magnitude of the correction retard amount is set to the first predetermined value or the first predetermined value by the learning control. In a knocking control method for an internal combustion engine, which controls knocking by subtracting a sum with a learning retardation amount that is rewritten when the second predetermined value has an absolute value smaller than the absolute value, the vibration sensor output is When there is an abnormality, the learned retard amount is held without being changed, and the corrected retard amount is set to a predetermined value, which is determined in advance from the basic ignition advance angle. The method for knocking control of an internal combustion engine is characterized in that ignition is performed with a value obtained by subtracting the maximum retardation amount as the ignition advance angle.