JPS6027782A - Method of controlling knocking of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the angle of the ignition timing from being delayed excessively in a method wherein learned control is carried out in accordance with the strength of knocking, by suspending the learned control at the transitional period where the state of an engine changes sharply. CONSTITUTION:In case an electronic control circuit 34 carried out learned control in accordance with the strength of knocking, the addresses in an RAM 36 of four points surrounding a point representing the present engine condition that is determined in accordance with the rotational frequency (N) of the current engine and the amount of intake air, that is, a load Q/N, are obtained in a learning map. Then based on the data of the addresses of the four points, an amount thetaKG of the learned delay angle is determined using two-dimensional interpolation technique. Then it is judged whether the engine is in the transitional state or not. If it is in the transitional state, the leaning is suspended. Thus, the angle of the ignition timing can be prevented from being delayed excessively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a knocking control method for an internal combustion engine, and more particularly to a knocking control method that performs learning control to perform precise knocking control.

Conventionally, the basic ignition advance angle is determined according to the engine speed and the engine load (intake pipe pressure or intake air amount per engine revolution), and when knocking occurs in the knock control region, a correction retard amount is determined. There is a known method of controlling ignition timing by increasing the value of the ignition timing and reducing the amount of correction retardation when knocking does not occur, and controlling the ignition timing with a value obtained by subtracting the amount of correction retardation from the basic ignition advance angle. . In order to precisely control knocking in this method, a learned retard amount was calculated and stored based on the corrected retard amount changed as described above, and the operating conditions were shifted from a 7-knock non-control area to a 7-knock control area. Sometimes, when the engine condition suddenly changes, such as when the torque ratio of the torque converter changes due to the value obtained by subtracting the learned retardation amount from the basic ignition advance angle, the knocking control can follow up and prevent knocking. It is more likely to occur. Therefore, in such a transient state, a large amount of knocking will occur, and the amount of correction retardation will gradually increase in order to prevent the engine from knocking. Furthermore, since the learning retard amount is learned based on the corrected retard amount,
It increases with the amount of correction retardation. Therefore, if the learned retard amount is larger than necessary, the ignition timing will be excessively retarded when using the learned retard amount to control the ignition timing.
There was a problem that the torque decreased.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a knocking control method for an internal combustion engine that prevents the learning retardation amount from becoming abnormally large and prevents a decrease in torque.

In order to achieve the above object, the configuration of the present invention calculates a corrected retard amount, updates a learned retard amount based on the corrected retard amount, and prevents knocking based on the corrected retard amount and the learned retard amount. In a knocking control method for an internal combustion engine, updating of the learned retardation amount is stopped during a transient state where the engine condition suddenly changes.

According to the above configuration of the present invention, since the learned retard amount is not updated during a transient period, the learned retard amount does not become abnormally large, and therefore, it is possible to prevent an unnecessary decrease in torque. .

Next, FIG. 1 shows an example of an internal combustion engine to which the present invention is applied. As shown in the figure, this engine is equipped with an air flow meter 2 as an intake air amount sensor provided downstream of an air cleaner (not shown). The air flow meter 2 includes a convention plate 2A that is rotatably provided in a damping chamber, and a potentiometer 2B that detects the opening degree of the two convention motion plates. 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 an O2 sensor for controlling the air-fuel mixture to near the stoichiometric air-fuel ratio, and 24 is a cooling water temperature sensor for detecting the engine cooling water temperature. - The 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 30 outputs a cylinder discrimination signal to an electronic control circuit 34 constituted by a microcomputer or the like, for example, every 720 degrees of crank angle, and this engine rotation angle sensor 32 outputs a cylinder discrimination signal, for example, every 30 degrees of crank angle. A reference position signal is output to the electronic control circuit 34.

The electronic control circuit 34, as shown in FIG.
Access memory (RAM) 36, read only memory (ROM) 38, and central processing unit (CPU) 4
0, a clock (CLOCK) 41, a first input/output port 42, a second input/output port 44, a first output port 46, and a second output port 48. , RAM36, ROM38, CPU40. CLOCK4
1 first input/output boat 42, second input/output boat 44,
The first output port 46 and the second output port 48 are
It is connected to bus 50. First input/output boat 4
2 includes a buffer (not shown), a multiplexer 54,
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. This multiplexer 5
4 and the A/D converter 56 are controlled by the signal output from the first input/output port 42. The second input/output port 44 is connected to an oxygen sensor 22 via a buffer (not shown) and a comparator 62, and a cylinder discrimination sensor 30 and an engine rotation angle sensor 32 are connected via a waveform shaping circuit 64. There is.

Further, the knocking sensor 18 is connected to the second input/output port 44 via a bandpass filter 60, a peak hold circuit 61, a channel switching circuit 66, and an A/D converter 68'ft. This bandpass filter is connected to a channel switching circuit 66 via an integrating circuit 63. This channel switching circuit 66 receives a control signal output from the second input/output port 44 for inputting either the output of the peak hold circuit 61 or the output of the integrating circuit 63 to the A/DW converter 68. is input, and a reset signal is input to the peak hold circuit 61 from the second input/output port 44. Further, the first output port 46 is connected to the igniter 28 via the drive circuit 70.
The second output port 48 is connected to the fuel injection device 12 via a drive circuit 727.

The ROM of the electronic control circuit 34 stores in advance a map of the basic ignition advance angle θBABK, which is expressed by the engine rotational speed and the intake air -3t (load) per engine rotation.

Next, an embodiment in which the present invention is applied to the engine as described above will be described in detail. Note that although the following description will be made using the next most inconvenient numerical values to avoid complication, the present invention is not limited to these numerical values, and the optimum value is selected for each type of engine.

Figure 3 shows the interrupt routine every 120° CA. First, in step 80, it is determined whether the intake air Jl (load) Q/Ni per engine revolution exceeds 0.511/rev. By doing so, it is determined whether or not the knocking control area is reached. Load Q/Ni is 0.5 A'/
rev, that is, in the knocking non-control region, the corrected retard amount θki is set to O in step 81, the flag fl is set in step 82, and the process proceeds to step 98. When the load Q/Ni exceeds 0,513/rev,t-, that is, in the knocking control region, it is determined in step 83 whether the flag f1 is set. Flag f! is set, that is, when the engine command shifts from the knocking non-control area to the knocking control area, in step 84, the learning retardation amount θKciO value stored in the RAM is changed to the corrected retardation amount θK.
i, the flag f1 is reset in step 85, and the process proceeds to step 98. On the other hand, if the flag fl has been reset, it is determined in step 86 whether or not knocking has occurred.

Whether or not non-king has occurred can be determined by checking the predetermined crank angle range of the electrical signal output from the knocking sensor (for example,
The determination is made by comparing the peak value at 10° CA ATDC to 500 CA ATDC) with the determination level determined by multiplying the background level obtained by integrating the electrical signal by a constant.

When it is determined in step 86 that knocking has occurred, in step 87 the previous corrected retardation amount θKj−1
0.1° CA is added to increase the correction retard amount, and the process proceeds to step 92. When it is determined in step 86 that knocking has not occurred, the count value cl of the first counter is incremented by 1 in step 88, and in step 89, the count value C1 is determined to be 10 (3, rotations) or more. to judge. When the count value c1 becomes 10 or more, the previous correction retard amount θ is determined in step 9o.
The corrected retard amount is reduced by subtracting 0.10 CA from xi-1, and the count value is set to C1kO in step 91. After fc, the process proceeds to step 92. On the other hand, the count value C.

If is less than 10, the process directly proceeds to step 92.

In step 92, the current load Q/Ni'ii is taken in, and in step 93, the current load Q/N + and the previous load Q are taken in.
/Ni-1. Q/Ni≧1.2 Q
/Nj-1, it is determined that it is a transient state, and the count value c2 of the second counter is set to 0 in step 96, and step 9
Proceed to step 8. When Q/Ni < 1.2 Q/Ni-1, it is determined that there is no transient state, and the count value C2 is incremented by 1 in step 94, and the count value c*y! is incremented in step 95. Determine whether zE is 10 or more. When the count value C, is 10 or more, the learning delay angle θKG for both times
The weighted average of j-1 and the current correction retardation amount θxi is used to obtain the current learning retardation amount θKatf: which is calculated as P, A.
The information is stored in a predetermined area of M and the process proceeds to step 98. on the other hand,
If the count value C2 is less than 10, proceed to step 9.
Proceed to step 8.

As a result of the above, the learned retard amount is not updated in a transient state, and the learned retard amount is updated after a predetermined period of time has passed in a state other than the transient state.

Further, in step 98, the corrected ignition retard amount θKi changed in steps 87 ia and 90 is subtracted from the basic ignition advance angle fJ BA8m read from the ROM, and the ignition advance angle θ executed in °C is subtracted.
I put it on. Then, in the primary igniter control routine, the igniter is controlled so that it is ignited at an effective ignition advance angle of 0.

Next, an embodiment in which learning control similar to the above is performed will be described. This knocking control method using learning control is based on the basic ignition advance angle θB18m', which is predetermined by the load determined by the engine rotational speed N, the ratio Q/N't of the intake nitrogen amount Q and the engine rotational speed N, and the intake pipe negative pressure. i Store it in the read-only memory (ROM) of the microcomputer in the form of a map, calculate the ignition advance angle θ that actually controls the igniter based on the following equation (1), and calculate this ignition advance angle. This is used to control knocking.

θ = θBA81-(θKG+θK) ・・・・・・
... (However, θKG is a learning retard angle t that is determined by the engine speed and load and is changed by learning control in order to bring the knocking level to a predetermined level.
, θ is a correction retard amount that retards the ignition timing when knocking occurs and advances the ignition timing when knocking no longer occurs.

Here, for the corrected retardation amount θ, the peak value and the judgment level are used in the same way as above to determine whether or not knocking has occurred, and when knocking occurs, knocking occurrence 1 range fi0 is calculated as shown in equation (2). .4°CA is increased and knocking does not occur for a specified period of time (for example, 48 m5ec)
As shown in equation (3), when the crank angle continues, it is reduced by 0.08° CA for each predetermined crank angle.

To θ ← To θ +0.4'CA ...Song, song, (2) To θ ←
+0.08° CA to θ...Song...(3) Also, the learned retard amount θKG according to the engine conditions is calculated as follows. 1. As shown in the fourth prisoner, prepare addresses 0 to 23 in the microcomputer's random access memory 'J (RAM) to store the learning retardation amount in correspondence with the engine speed N and load Q/N. Create a learning map. The engine speed N and intake air amount Q are taken in, and a point (
N, Q/N) Find the RAM addresses of the four points surrounding k. now,
As shown in Figure 5, point 10 indicates the current engine stock A↑
The RAM address is 11.11+1, n+6, n+7 (7
c, n = 0, lo,...16) At address n, learn retard amount (7xon, at address n+1, learn retard angle Jl)
(/KCk(n+1), address n+6 has learning retardation amount θ
K G (n+8), learning retard amount θK at address 11+7
It is assumed that G(n-1-7) are respectively stored. Then, the difference in engine speed between addresses is 'Ir, If 4 is the load difference 'ty between the ground n and the point indicating the current engine condition, then the two-dimensional interpolation method shown in the following equations (4) to (6) υ is the point indicating the current engine condition. The learning retardation amount θKG is calculated.

Next, an embodiment in which the present invention is applied to the knocking control method described above will be described. Moat step 1o.

In this step, four RAM addresses surrounding the point indicating the current engine condition determined by the engine speed N and the load Q/N are placed on the learning map. The above (4) According to formulas (5) and (6), the learning retardation amount/θKG at the point indicating the current engine condition is calculated by two-dimensional interpolation, and the calculated value is stored in the RAM.
is stored in a predetermined area. In the slab 102, it is determined whether or not there is a transient state in the same manner as in the above embodiment, and if it is a transient state, the process directly proceeds to the next routine, and if it is not a transient state, the following learning control is performed. That is, step 103
At h, did the count value TIME of the timer incremented every 'l m sec in the m3 interrupt routine become 40 (160 m5ec) or more? C41 is disconnected, and if the count value 'r IME is less than 40, the next routine is executed as is.

On the other hand, if the count value TIME is 40 or more, in step 104 the count 1rlL 'j' I M E 'a
-0.

In step 105, it is determined whether the corrected retard amount OK is 2° CA or more. When the corrected retardation amount OK is less than 2° CA, a point indicating the current engine condition is determined in step 108. ]l: Performs learning control to subtract 0.04°CA from each of the learning retard amounts stored at four points on the surrounding learning map. As a result, when the corrected retard amount θK is equal to or less than 28CA, the learned retard amount is set to the learning side so as to be smaller, and the ignition timing is controlled to be advanced by the learned retard amount. On the other hand, when the corrected retard amount θK is 2°C or more, it is determined in step 106 whether the corrected retard amount θK is less than 4'CA. When the corrected retard amount θK is less than 4°CA,
That is, when 2°CA≦θK<4'CA, learning control is not performed, and when the corrected retardation amount OK is 4°CA or more, in step 107, 4 on the learning map surrounding the point indicating the current engine condition is Learning control is performed to add 0.04° CA to each of the learning retard amounts stored at the points. As a result, when the second correction retard amount θK is 4° CA or more, learning control is performed so that the learned retard amount becomes large, and the ignition timing is controlled to be delayed by the learned retard amount.

The relationship 't between the conditions of the corrected retard amount θX and the increase/decrease of the learning retard amount θKG in the above learning control is summarized in the following table.

The learning retard amount θKG learned as described above and the corrected retard amount θ that is changed depending on whether or not knocking occurs are substituted into the above equation (0) to obtain the effective ignition advance angle θ.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an engine to which the present invention is applied, FIG. 2 is a block diagram of the electronic control circuit shown in FIG. 1,
FIG. 3 is a flowchart showing a processing routine of an embodiment of the present invention;
FIG. 4 is a diagram showing a learning map used in another embodiment of the present invention, FIG. 5 is an explanatory diagram showing four points on the learning i-tub surrounding a point indicating the current engine condition, and FIG. is a flowchart showing a processing routine of the above other embodiment. 18... Knocking sensor, 28... Igniter,
34...Electronic control circuit. Agent Tatsuyuki Unuma (and 1 other person) Figure 4 Figure 5

Claims (1)

[Claims] (!) In addition to setting a corrective retard amount that retards the ignition timing when knocking occurs and advances the ignition timing when knocking does not occur, the learned retard amount is updated by learning control based on the corrected retard amount. , in the 7-king control method for an internal combustion engine that controls knocking based on the corrected retard amount and the learned retard amount, updating of the learned retard amount is stopped during a transition when the state of five engines suddenly changes. Knocking control method for internal combustion engines.