JPS59136575A - Control of knocking in multi-cylinder engine - Google Patents

Abstract

PURPOSE:To prevent the generation of output reduction by a method wherein the amount of spark delay angle of a specified cylinder, remote from a knocking sensor mostly, is made larger than other cylinders in only an operating area, in which the knocking upon high revolution and high load can not be detected easily. CONSTITUTION:An electronic control circuit 34 decides at a predetermined crank angle by the ratio of the amount of air Q, detected by an airflow meter 2, and a revolution signal N, detected by a sensor 32, whether an engine condition is in a knocking control area or not, and if it is in the control area and the generation of the knocking is detected by the signal of the knock sensor 18, the knocking is controlled by subtracting the correcting amount of the spark delay angle from the basic amount of spark delay angle. Here, the detection of knocking of the specified cylinder becomes difficult in accordance with the change of an operating condition which is entering into the high revolution and high load area, therefore, the amount of spark delay angle of the specified cylinder, remote from the knocking sensor 18 mostly, is made larger than the other cylinders in only the high revolution and high load operating area. Thus, the reduction of the output of the engine and the deterioration of fuel consumption may be prevented even when the knocking control is applied to all of the cylinders simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a knocking control method for a multi-cylinder engine.
In particular, the present invention relates to a knocking control method that simultaneously retards ignition timing in all cylinders when knocking occurs.

Conventionally, a knocking sensor consisting of a microphone or the like is attached to the engine block, converts engine vibration into an electrical signal, and detects the peak value a of the electrical signal and the judgment level Kb.
When the peak value a exceeds the determination level Kb, it is determined that knocking has occurred, and the ignition timing is delayed.
A knocking control method is known in which it is determined that knocking does not occur when the peak value a becomes equal to or less than the determination level Kb, and the ignition timing is advanced. Here, the peak value a is calculated by inputting an electrical signal to a peak hold circuit through a bandpass filter that allows the frequency band (7 to 8 kHz) specific to knocking to pass, and calculating the peak value a by 10° CA during the explosion process of the incense cylinder.
ATDC ~ 50° CA It is obtained by holding the peak value in a predetermined crank angle range around ATDC. Further, the determination level Kb is obtained by multiplying an electrical signal unrelated to combustion in the engine by a pack ground level b l/fi constant K, which is obtained by integrating an electrical signal unrelated to combustion in the engine using an integrating circuit. In this knocking control method, the knocking sensor is installed on the side wall of the engine block at the approximate center, so the distance from the knocking sensor to the common cylinder varies.
Even if knocking of the same intensity occurs in each cylinder, the vibration due to knocking will be attenuated in proportion to the distance, and the peak value will be different for the common cylinders, making it particularly difficult to detect knocking in the cylinder farthest from the knocking sensor. It was difficult.

For this reason, in the case of a 6-cylinder engine, as shown in Figure 1,
Knocking is caused by protrusions that are rotated and opposed in turn on the tip surface of a pole piece that is fixed to a distributor shaft that is driven by a cedar reduction ratio with respect to the engine crankshaft and has a pickup coil wound around its tip. A method is adopted in which the protrusion 1 corresponding to the sixth cylinder 6 which is farthest from the sensor is previously displaced to the retard side by a predetermined crank angle X/2'CA.

However, in this method of displacing the protrusion of the distributor in advance, the ignition timing is retarded for all ranges of engine operating conditions, resulting in an unnecessary reduction in output and deterioration in fuel efficiency.

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 a multi-cylinder engine that does not cause a decrease in output or deterioration of fuel efficiency even when knocking control is performed on all cylinders simultaneously. .

In order to achieve the above object, the present invention has a structure in which the retardation noise of a specific cylinder farthest from the knock sensor is detected only in an operating range where chain acid knocking is difficult to detect at a predetermined engine speed or higher and at a predetermined load or higher. is made larger than the retard angle of other cylinders. Furthermore, as the operating conditions change to a high engine speed and high load region, it becomes difficult to detect knocking in a specific cylinder, so in the configuration of the present invention, the retard angle increases as the engine speed and load increase. is preferable.

Next, FIG. 2 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 make 2 as an intake air mass sensor downstream of an air cleaner (not shown). The air flow meter 2 includes 12 compensation motion plates rotatably provided in a damping chamber and a potentiometer 2B that detects the opening degree of the compensation plate 2A. Therefore, the intake air meter is detected from the voltage output from the potentiometer 2B. Also,
An intake air temperature sensor 4 is provided near the air flow meter 2 to detect the temperature of intake air.

A throttle sotol valve 6 is arranged downstream of the air flow meter 2, and a surge tank 8 is arranged downstream of the throttle valve 6. 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 the engine itself! The engine combustion chamber 14A is connected via an exhaust manifold 16 to a catalytic converter (not shown) filled with a three-way catalyst. Next to the engine body 14, a knocking sensor 18 is provided which is composed of a microphone or the like and detects vibrations of the engine due to combustion. Note that 20 is a spark plug, 22 is an 02 sensor for bringing the air-fuel mixture near the stoichiometric air-fuel ratio through feedback control, and 24 is 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 eve knife 28. The distributor 26 is provided with a cylinder discrimination sensor 30 and an engine rotation angle sensor 32, each of which includes a pickup fixed to the distributor housing and a signal rotor fixed to the distributor shaft. This cylinder discrimination sensor 30 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. 3, 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,
It is configured to include a second human output port 44, a first output port 46, and a second output port 48, and includes a RAM 36,
I70IVI38, CPU40, CLOCK41, 1st
The input/output port 42, the second input/output port 44, the first output port 46, and the second output port 48 are connected to a bus 50 such as a data bus or a control bus.

The first input/output boat 42 includes a buffer (not shown),
Multiplexer 54, analog-digital (A/D)
The air flow meter 2, cooling water temperature sensor 24, intake air temperature sensor 4, etc. are connected via the converter 56. The multiplexer 54 and the A/R converter 56 are connected to the first
It is controlled by a control signal output from the human output boat 42.

The second input/output boat 44 includes 7a (not shown).
Q and SEF f22 are connected through the OYOHIKO 1 comparator 62, and the cylinder discrimination sensor 3 is connected through the waveform shaping circuit 64.
0 and engine rotation angle sensor v32 are connected.

Further, the knocking sensor 18 is connected to the second human output port 44 via a bandpass 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 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 gate 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 electronic control circuit 340 ROM 38 stores basic points Odori (expressed by engine speed and intake air pressure (or load)).
θB A S E) correction value θ61. based on the rotation speed shown in FIG. The correction value θ62 due to the load and the basic fuel injection ratio are stored in advance, and the air flow meter 2
The basic ignition advance angle and the basic fuel injection angle are read out based on the signals input from the engine rotation angle sensor 32 and the signals input from the engine rotation angle sensor 32. According to the signal, a correction retard angle paper and a correction fuel injection meter are added to the basic ignition advance angle and basic fuel injection needle, 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.

Next, an embodiment in which the present invention is applied to the engine as described above 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. 4 shows the middle of an interrupt routine that is executed every predetermined crank angle (for example, 90° CA B T I C) for calculating the corrected retard angle θK. In step 80, the A/D-changed peak value 2 is compared with the A7D-converted judgment level Kb obtained by multiplying the constant K by the A7D-converted peak value 2 in the same way as in the past, and it is determined whether or not knocking has occurred. If knocking occurs, the corrected retarded cornea θK is increased by a predetermined value (for example, 0.4° CA) in step 82, and the process proceeds to step 84.

On the other hand, if knocking does not occur t7, step 8
At step 1', it is determined whether the count value T I M E 1 of a timer that counts the time during which no knocking occurs is greater than or equal to a predetermined value (for example, 12). The count value of this timer is incremented by 1 every predetermined time (for example, 4 rl't-1 sec), and the count value 12 in step 81 represents 48 m sec.

If the count value 'rIME1 is greater than or equal to the predetermined value, this means that a state in which no knocking occurs has continued for a predetermined period of time, so the correction steering angle amount θK is decreased by a predetermined value (for example, 0.080 CA) in step 83. Go ahead.

On the other hand, when the count value TIMFJl is less than the predetermined value,
Proceed to the next routine. Then, in step 84, the timer is cleared.

A routine for correcting the corrected attack angle meter calculated as described above to make the corrected retard angle of a specific cylinder larger than the retard angle of other cylinders will be explained with reference to FIG.

This routine is performed at a predetermined crank angle (for example, 120'C
A) This is executed by each interrupt, and the specific cylinder is the 6th cylinder +6 of a 6-cylinder engine. First, in step 90, based on the cylinder discrimination signal and the crank angle reference position signal, the next cylinder to be ignited is the 6th cylinder +
The next cylinder to be ignited is the 6th cylinder 4-
If not 6, the basic ignition advance angle θBA determined by the engine speed N and the load Q/N (ratio of intake air tQ and engine speed N) is determined in step 96 as usual.
The value obtained by subtracting the correction retard number θK from SE is the ignition advance angle θig.
The process then proceeds to step 95. On the other hand, if the next cylinder to be ignited is the 6th cylinder + 6, then in step 92 a correction value for the current engine speed N is calculated from the correction amount for the engine speed N stored in advance in the ROM (Fig. 6). θ61 is read out and stored in the RAM, and at the same time, in step 93, the correction amount 062 for the current load Q/H is read out from the load correction piece (FIG. 7) previously stored in the ROM and stored in the RAM. Next step 9
4, the correction amount θ61 and correction lθ obtained above are
62 is added to the corrected angle of attack meter θK to correct the corrected retard angle θK, and the corrected retard number θ is +061+θ6 from the basic ignition advance angle e BABE! The value obtained by subtracting is the ignition advance angle θi
Then, in step 95, a time coincidence interrupt is set so that the ignition is ignited at an ignition advance angle of O1g, and the process returns to the main routine. Thereafter, at the time of the time coincidence interrupt, the igniters are turned off in order and the 1st to 6th cylinders are ignited at θBASE -θ, and the 6th cylinder is ignited at θBABE-(θ +061+06
2) is ignited. Furthermore, as shown in Fig. 6, the correction i''at is 0 when the engine speed is less than the predetermined engine speed, and the correction amount 062 is 0 when the load is less than the predetermined load. Only a specific cylinder is retarded to a greater extent than other cylinders.

As explained above, according to the present invention, the unique effect of being able to prevent a decrease in output and a deterioration in fuel efficiency on the low engine speed side and low load side can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the protrusions of a conventional distributor rotor, FIG. 2 is a schematic diagram showing an example of an engine to which the present invention is applied, and FIG. 3 is a block diagram showing the electronic control circuit of FIG. Figure 4 is a flowchart showing a routine for calculating the corrected retardation amount, Figure 5 is a flowchart showing a routine for correcting the corrected retardation amount according to the engine speed and load, and Figure 6 is a flowchart showing a routine for calculating the correction amount for the engine speed. The diagram shown in FIG. 7 is a diagram showing the amount of correction for the load. 2... Air flow meter, 18... Knocking sensor, 32... Engine rotation angle sensor. 34...Electronic control circuit. Agent Tatsuyuki Unuma (and 2 others)

Claims (2)

[Claims] (1) A knocking sensor is used to detect engine knocking, and a correction retard is subtracted from a predetermined basic ignition advance angle, which retards the ignition timing when knocking is detected and advances the ignition timing when no knocking is detected. In a knocking control method for a multi-cylinder engine in which knocking is controlled simultaneously on all cylinders, a corrected retardation experiment is performed on a specific cylinder farthest from the knocking sensor in an operating range above a predetermined engine speed and an operating range above a predetermined load. A knocking control method for a multi-cylinder engine characterized by increasing the correction retardation angle of the cylinders. (2) The multi-cylinder engine 9 knocking control method according to claim 1, wherein the corrected retardation angle is increased as the engine speed and load increase.