JPS59113266A - Control of knocking in internal-combustion engine - Google Patents

Abstract

PURPOSE:To keep a knocking frequency in constant by a method wherein a time interval between the generation of knocking of this time and the same of next time is measured and the delaying amount of a correcting spark angle is increased when the time interval is shorter than a first predetermined time while it is decreased when the same is longer than the second predetermined time. CONSTITUTION:In a step 81, the time interval between the generation of knocking of this time and the same of next time is decided whether it is shorter than the first predetermined time (0.5s for example) or not. If the decision is YES, the delaying amount thetak of the correcting spark angle is increased. On the other hand, above-described time is decided whether it is longer than the second predetermined time (0.8s for example) or not. If it is YES, the delaying amount thetak of the correcting spark angle is decreased. According to this method, the frequency of the generation of the knocking may be kept in constant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a knocking control method for an internal combustion engine.

Conventional knocking control is performed as follows. First, a knocking sensor composed of a microphone or the like is attached to the engine to detect engine vibration, and a determination level is determined by multiplying the peak value of the engine vibration by a predetermined value and the average value of the engine vibration. Next, the peak value is compared with the judgment level, and when the peak value exceeds the judgment level, it is judged that knocking has occurred, and the value is subtracted from the basic ignition advance angle θBAf1g, which is determined according to the engine speed and load. The ignition timing is retarded by increasing the corrected retard amount θK. On the other hand, when the peak value is below the determination level, it is determined that knocking has not occurred, and the corrected ignition retard amount θK is subtracted from the basic ignition advance angle θBA8E when the state in which knocking does not occur continues for a predetermined time or a predetermined number of ignitions. The ignition timing is advanced by decreasing the ignition timing.

By the way, knocking occurs at the optimum ignition timing in terms of both output and knocking sound, and occurs at a rate of about 1 at Is. However, in the conventional method described above, the ignition timing is immediately retarded as soon as the occurrence of knocking is detected, so the ignition timing is unnecessarily retarded too much, resulting in a decrease in output and deterioration of fuel efficiency, or the ignition timing is delayed. There was a problem in that there was a risk of fluctuations.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a knocking control method that does not cause unnecessary retardation or fluctuations in ignition timing.

In order to achieve the above object, the configuration of the present invention is such that, in the conventional knocking control method, the time between the occurrence of the current knocking and the occurrence of the next knocking is measured, and this time When this time is longer than the second predetermined time, the corrected retard amount is decreased, and when this time is longer than the first predetermined time and the second predetermined time, the correction retard amount is increased. When the value is between 1 and 2, the corrected ignition retard amount is not increased or decreased, but is subtracted from the basic ignition advance angle to control knocking. Here, in order to achieve the desired purpose, it is considered that knocking control is performed by increasing or decreasing the corrected retard amount depending on the number of times of ignition. but,
In such a method, the frequency of occurrence of knocking differs depending on the engine speed, so a problem arises in that if the number of occurrences of knocking is large depending on the engine speed, the driver feels uncomfortable.

According to the configuration of the present invention described above, a unique effect can be obtained in that the frequency of knocking occurrence can be kept constant without causing the problems seen in the modified example described above.

Next, FIG. 1 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 microcomputer, and as shown in the figure, is equipped with an air flow meter 2 as an intake air amount sensor downstream of an air cleaner (not shown). The air flow meter 2 includes two conven motion plates rotatably provided in the damping chamber, and a potentiometer 2B that detects the opening degree of the compensation gray) 2A. Therefore, what is the amount of intake air? The voltage output from the tensimeter 2B) is detected. Also,
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 lo. The intake manifold l'10 is connected to the combustion chamber 14A of the engine body 14, and is connected to a catalytic converter (not shown) filled with a three-way catalyst via the combustion chamber 14 of the engine and the Ad exhaust manifold 16. . The engine body 14A is provided with a knocking sensor 18, which is composed of a microphone or the like, and detects vibrations of the engine due to combustion. In addition, 20 is a spark plug, and 22 is a feedback control system that controls the air-fuel mixture to near the stoichiometric air-fuel ratio.

0 to be around. Reference numeral 24 denotes a cooling water temperature sensor for detecting the engine cooling water temperature.

A spark plug 20 attached to the engine 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 discrimination sensor 3o and an engine rotation angle sensor 32, each of which includes a pickup fixed to the distributor housing and a signal loaf fixed to the distributor shaft. This cylinder discrimination sensor 3o outputs a cylinder discrimination signal to an electronic control circuit 34 made up of a microcomputer or the like every 720 degrees of the crank angle, for example, and the engine rotation angle sensor 32 outputs a cylinder discrimination signal based on the crank angle every 30 degrees of the crank angle. A position signal is output to the electronic control circuit 34.

As shown in FIG. 2, 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, a first Input/output boat 42
, a second input/output port 44, a first output port 46, and a second output port 48, and the RAM 36
, ROM38, CPU40, CLOC! The first input/output port 41, 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 path.

The first input/output port 42 includes a buffer (not shown),
Multiplexer 54, analog-digital (A/D
) The air 70-meter 2, cooling water temperature sensor 24, intake air temperature sensor 4, etc. are connected via the converter 56.

The multiplexer 54 and A/D converter 56 are controlled by a control signal output from the first input/output port 42.

The O sensor 22 is connected to the second input/output port 44 via a buffer (not shown) and a comparator 62, and a cylinder discrimination sensor 30 and an engine rotation angle sensor 32 are connected via a waveform shaping circuit 64. ing. Also,
The second input/output port 44 includes a band/4 filter 0, a peak hold circuit 61, and a channel switching circuit 66.
and the knocking sensor 18 via the A/D converter 68.
is connected. The channel switching circuit 66 is connected to the channel switching circuit 66 via a pantone filter integration circuit 63. A control signal for inputting either the output of the peak hold circuit 61 or the output of the integrating circuit 63 to the A/D converter 68 is input to the channel switching circuit 66 from the second input/output port 44. Further, a reset signal and a dirt signal are inputted 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 a drive circuit 70, and the second output port 48 is connected to the fuel injection valve 12 via a drive circuit 72.

The ROM 38 of the electronic control circuit 34 stores in advance a basic point map expressed by engine speed and intake air amount (or load), basic fuel injection amount, etc.
The basic ignition advance angle and 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 out. A corrected retard amount and a corrected fuel injection amount are added to the basic ignition advance angle and basic fuel injection amount by various signals including p, and the igniter 28 and the fuel injection valve 12 are controlled. 0. The air-fuel ratio signal output from the 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.

Next, an embodiment in which the present invention is applied to the above-mentioned machinery/gins will be described in detail. In addition, in explaining the present invention in detail, the main routines of fuel injection control, air-fuel ratio control, ignition timing control, etc. are the same as those of the conventional art, and therefore their explanations will be omitted.

FIG. 3 shows the knocking control routine of this embodiment. In step 80, it is determined whether or not knocking has occurred using a method similar to the conventional method. When knocking occurs, in step 81 it is determined whether the time between the current occurrence of knocking and the next occurrence of knocking is shorter than a first predetermined time (for example, O, SS).

This time is detected by a counter C which is incremented by 1 every time the distance decreases by 4 m, for example. Note that the count value 125 at step 81 indicates 0.58.

If the time between knocks is shorter than the first predetermined time, the corrected retard amount θK is increased (eg, increased by 1° C.A) in step 82, and the process proceeds to step 87. If the time between knocks is longer than the first predetermined time,
After clearing counter C in step 83, step 87
Proceed to.

On the other hand, if knocking does not occur, step 84 determines that the time between knocks is set to a second predetermined time (for example, O
, S S ).

The count value 200 of the counter C in step 84 is 0.
88 are excerpted. If the time between knocks is longer than the second predetermined time, the corrected retard amount θK is decreased (for example, decreased by 1°C) in step 85, and the counter C is cleared in step 86 to move to Stella f87. move on. If the time between knocks is shorter than the second predetermined time, the process directly proceeds to Stella f87.

In step 87, the ignition advance angle θ is calculated by subtracting the corrected ignition retard amount θK changed as described above from the basic ignition advance angle θBA8]C determined according to the engine speed and load. Then, the time to turn on and off the igniter is determined from this ignition advance angle θ and the current crank angle, and the igniter is controlled so that it is ignited at the ignition advance angle θ.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an ENZO/ to which the present invention is applied, FIG. 2 is a block diagram of the electronic control circuit of FIG. 1, and FIG. 3 is a flowchart of an embodiment of the present invention. 2...Air flow meter, 18...Knocking sensor, 32...Engine rotation angle sensor, 34...Electronic control circuit, Agent Tatsuyuki Unuma (and 2 others)

Claims (1)

[Claims] (1) Determine the basic ignition advance angle in advance according to the engine speed and load, detect the occurrence of engine knocking, and subtract the correction retard amount from the basic ignition advance angle when knocking occurs. In a knocking control method for an internal combustion engine that controls knocking, the time between the current knocking occurrence and the next knocking occurrence is measured,
When the time is less than or equal to the first predetermined time, the correction retard amount is increased, and the second time is longer than the first predetermined time.
When the time is longer than a predetermined time, the corrected retard amount is decreased, and when the time is between the first predetermined time and the second predetermined time, the knocking is controlled without increasing or decreasing the corrected retard amount. A knocking control method for an internal combustion engine, characterized in that: