JPS5974372A - Engine ignition timing control method - Google Patents

Abstract

PURPOSE:To restrain the generation of knocking in each engine cylinder, by obtaining the frequency of knocking detected in each cylinder, and as well by changing the spark advance compensating amount of ignition timing in each cylinder in accordance with the degree of the detected knocking frequency. CONSTITUTION:The number of an engine cylinder which has been ignited just before, is discriminated in view of a signal from an engine cylinder discriminating sensor 1, and is set to ''n''. Judgement is made on whether knocking is generated in each cylinder ignited just before or not, and if it is generated, 6 is added to the frequency KNOCK (n) of detected knocking in each cylinder ignited just before. Accordingly, the more the frequency of detected knocking an engine cylinder has, the greater a delay in its ignition timing is. By obtaining the frequency of detected knocking of each cylinder to change the spark advance compensating amount of ignition timing in accordance with the degree of the frequency of detected knocking, as above-mentioned, the generation of knocking in each cylinder may be restrained, thereby the output power of the engine may be aimed at being enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine ignition timing control method that corrects and controls ignition timing depending on whether or not engine knocking occurs.

Ignition timing control devices are well known that detect the presence or absence of knocking occurring in an engine using a knocking sensor, and control the knocking by reflecting the detection result on the ignition timing.

When detecting knocking in multiple cylinders with a single knocking sensor, the detection output of the knocking sensor when knocking occurs generally has a lower level as the cylinder is farther away from the knocking sensor. Knocking becomes difficult to detect. Therefore, with the conventional method of delaying the ignition timing by a certain amount when knocking is detected, and advancing the ignition timing by a certain amount if knocking is detected, for example, if knocking is occurring but cannot be detected, Since the ignition timing is advanced by a certain amount, knocking is more likely to occur. As a countermeasure to this, by decreasing the amount of advance of the ignition timing,
When the state of the engine changes from a state where knocking is likely to occur to a state where knocking is difficult, the ignition timing is delayed from the appropriate ignition timing, resulting in a decrease in engine output. Furthermore, when knocking is detected in a cylinder that is difficult to detect, that is, far from the cylinder to which the knocking sensor is installed, if the engine is retarded by a certain amount in the same way as other cylinders, the knocking will not occur even though knocking has occurred. I'd like to take into account conditions that could not be detected, so I'm worried that knocking will occur.

As a countermeasure to this problem, if the amount of retardation of the ignition timing is increased, the ignition timing will be delayed from the appropriate ignition timing and the engine output will decrease.

As a countermeasure to the above, a method has been proposed in which cylinders in which knocking is difficult to detect are inspected in advance, and the ignition timing retard and advance amounts are made different for these cylinders than for other cylinders. It was not possible to correct changes in the ignition timing of cylinders, which makes it difficult to detect knocking during mass production and changes over time.

An object of the present invention is to provide an engine ignition timing control method that suppresses the occurrence of knocking and improves engine output.

A feature of the present invention is that a knocking sensor installed in a specific cylinder detects knocking that occurs in multiple cylinders, and controls the ignition timing of the fragrance 1vi based on the detected output. Time 1υI fbll fil
In the power method, the knocking detection frequency in the aroma cylinder is determined, and the ignition timing advance correction amount of each cylinder is changed depending on the magnitude of the knocking detection frequency.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the overall configuration of an engine control device. In the figure, 1 is an engine, the intake air necessary for combustion is measured by an air meter 70, and is fed into a throttle chamber 3. The air is taken into the engine 1 through the provided throttle valve 6, surge tank 8, and intake manifold 10. Here, the air flow meter 2 converts the opening degree of a measuring brake (2A) that changes according to the adult air flow rate into an electrical signal by a potentiometer (2B) linked to the measuring brake (2A), and the nuclear signal is sent to a control circuit (3).
Output to.

On the other hand, fuel is fed under pressure from a fuel system (not shown), the opening time of the injector 12 is controlled by a control signal from the control circuit 34, and a predetermined amount of fuel is periodically injected into the intake manifold 10.

The mixture introduced into cylinder 14A is then transferred to igniter 2.
8 through the distributor 26 to the spark plug 20
The engine 1 is ignited at a predetermined timing by an ignition signal output from the engine 1, and the exhaust gas is discharged to the outside through the exhaust manifold 9 through the exhaust pipe 16 during the exhaust stroke after each stroke of the engine 1.

Next, various sensors will be explained. 4 is an intake air temperature sensor that detects the temperature of suction air flowing into the throttle chamber 3; 18 is a knocking sensor that detects knocking occurring in the engine; 22 is a sensor 02 that detects the residual oxygen concentration in exhaust gas; is a water temperature sensor that detects the engine cooling water temperature. 30 and 32 are cylinder discrimination sensors fixed to the shaft of the distributor (5) computer 26, respectively;
This is an engine rotation speed sensor. The cylinder discrimination sensor 30 discriminates the cylinder to be ignited and detects the top dead center position of the piston 5. The engine rotation speed sensor 32 detects the engine rotation speed and detects the predetermined rotation angle (
For example, one pulse is output every 30°). The detection outputs of these various sensors are taken into the control circuit 34, and based on various control programs, an ignition timing control signal and a fuel injection control signal are output to the igniter 28 and the injector 12, respectively, and the ignition timing control and fuel injection control are performed. It will be done. Since the present invention relates only to ignition timing control, other explanations will be omitted.

Next, FIG. 2 shows the configuration of the control circuit 34. In the figure, 36 is a read-only memory (ROM) in which fixed data and various programs are stored, and 38 is a random access memory (RROM) for reading and writing various data.
AM), 41) is a central processing unit ((6) CPU) that also performs glaze calculation processing based on the program stored in R(11vl 36).

Further, 42.44 is an input/output port, 46.48 is an output port, 56 is an A/D converter that converts the analog signal taken in by the multiplexer 54 into a digital signal, and 6
4 is a waveform shaping circuit that shapes pulse-like signals from the cylinder discrimination sensor 30 and the engine speed sensor 32; 70.7
2 is a drive circuit 52A, 52B, 52C which amplifies the signal output from output capo-) 46.48 to a predetermined level.
are buffer amplifiers that amplify the detection outputs of the air 70-meter 2, water temperature sensor 24, and intake temperature sensor 4, respectively. 62 is a comparator that shapes the waveform of the output of the buffer amplifier 60, 66 is an input circuit that receives the output signal of the knocking sensor 18 and detects the knocking signal from the output signal, and 68 is the output signal of the input circuit 66. This is an A/D conversion circuit that takes in the data and converts it A/D.

Next, FIG. 3 shows the contents of the ignition timing control task executed by the control circuit board 34. This task is activated every 90° after the ascending point b in the crank rotation angle. In the figure, when the task is activated in step 80, the next task 82 determines the odd bone of the cylinder that was ignited immediately from the detection signal of the cylinder discrimination sensor 30, and sets this as n. Next, in step 84, it is determined whether knocking has occurred in the cylinder that was ignited immediately before. That is, the average value of the output of the knocking sensor 18 is determined, and this average value is multiplied by a predetermined value to determine a certain level. If the peak value of the knocking sensor 18 is greater than the predetermined level, it is determined that knocking has occurred. If it is smaller than a predetermined level, it is determined that knocking has not occurred. If it is determined 'Yes' in step 84, the process moves to step 86, and step 86
represents the knocking detection frequency of the incense cylinder (+M', K
Subtract 1 from N OCK (i). Here, 1 indicates the number of the aroma cylinder of the engine, and since this embodiment is aimed at a 6-cylinder engine, i=1 to 6 are used. In this step, the knock detection frequency of each cylinder is determined by KNOCK.
(1), K N 0CK (2), ... KNOCK (6
) is subtracted from each ]. KNO here
CK(i) is set to a value obtained by dividing a predetermined value a by the number of cylinders, 6, in an initial routine that is executed only once immediately before starting the engine.

Next, in step 88, the knocking detection frequency K N OCK (?L) of the cylinder that was ignited immediately before in step 82 is set to 6.
Add. Therefore, the sum of KNOCK(i) representing the knocking detection frequency at the end of step 86 for each cylinder is equal to the predetermined value a, and the value of KNOCK(i) representing the knocking detection frequency increases for the cylinder with a higher knocking detection frequency. growing. Further, in step 90, a value obtained by multiplying the reciprocal of the value KNOCK(yb), which represents the knocking detection frequency of the cylinder that was fired immediately before, obtained in step 88, by a predetermined value, is added to the knocking correction advance angle θK, and this added value is The knocking correction advance angle is set to θ. Here, the knocking correction advance angle θ is set at an initial routine that is executed only once immediately before starting the engine. Here, the larger the knocking detection frequency KNOCK(?L) of the relevant cylinder is, the smaller the knocking correction advance angle θ becomes.

On the other hand, if the determination in step 84 is "No", the process moves to step 94, and in step 94, a value K N OCK (?L) representing the knocking detection frequency of the relevant cylinder is determined from the knocking correction advance angle θK. ) to a predetermined value C'f
: Subtract the multiplied value and use this subtracted value as the knocking correction advance angle θ. In other words, the knocking detection frequency K N of the relevant cylinder
The larger OCK (?L) is, the smaller the knocking correction advance angle θ becomes. In step 94, the effective ignition timing θ is determined from the knocking correction advance angle θK calculated in steps 90 and 92 above. That is, in step 94, the value obtained by subtracting the knocking correction advance angle θK from the basic advance angle θB determined from the engine speed and engine load is set as the effective ignition timing θ, and the process proceeds to step 96. In step 96, the time at which the igniter 28 should be turned on is calculated from the execution ignition timing θ and the time when this interrupt task is started, and set in the output register provided in the output boat 46, and in step 98, the task is executed. finish.

As is clear from the above main content, when knocking is detected, the greater the knocking detection degree of the current cylinder, the smaller the ignition timing delay, and when knocking is not detected, the knocking detection (10) frequency of the cylinder in question is The larger the value, the more the ignition timing advances.

Next, FIG. 4 shows the contents of another embodiment of the ignition timing control task. Similar to the embodiment shown in FIG. 3, this task is also activated every 90 degrees after the top dead center of each cylinder. In the same figure, when a task is activated in step 100, in the next step 102, the number of the cylinder that was ignited immediately before is detected by the cylinder discrimination sensor 3.
The determination is made based on the detection output of 0, and this is set as n. Next, in step 104, it is determined whether or not knocking has occurred in the relevant cylinder based on the detection output of the knocking sensor 18, similar to the embodiment shown in FIG.
If it is determined that y eSl, in step 106, a value KNOCK (
In i), a value obtained by adding a predetermined value f to the knocking detection frequency KNOCK(?L) of the cylinder that was ignited immediately before in step 102 is set as the knocking detection frequency KNOCK(,). Therefore, the higher the knocking detection frequency, the higher the knocking detection frequency KNOCK(i). Further step 10
8, the knocking detection frequency K obtained in step 106
It is determined whether or not OCR(?L) is smaller than a predetermined value g, and if it is determined as Yes1, step 1 is performed.
If the determination in step 10 is "No", the process moves to step 112. Then, in steps 110 and 112, the knocking compensation advance angle OK is calculated. That is, the initial routine is executed only once before starting the engine. J to the initial value of knocking correction advance angle e K set in
The value obtained by adding 1 predetermined value and j is set as the knocking correction advance angle θ. Here, the predetermined value is set smaller than the predetermined value i, so the knocking detection frequency is
The larger (n) is, the smaller the knocking correction advance angle OK becomes.

On the other hand, if it is determined as NO1 in step 104, the process moves to step 114, and the value K NOCK (
? The value obtained by subtracting the predetermined value l from L) is set as the knocking detection frequency KNOCK(7L) for the cylinder.

Therefore, the value KNOCK(i) representing the knocking detection frequency of the cylinder with a low knocking detection frequency becomes small.

At step 116, it is determined whether or not the value K N OCK (R) representing the knocking detection frequency of the relevant cylinder is larger than a predetermined value m. .

If the determination is NO9, the process moves to step 120. Then, in steps 118 and 120, the values obtained by subtracting the predetermined values U and P from the knocking correction advance angle θK are set as the knocking correction advance angle θ, and then the process moves to step 122. In step 122, the value obtained by subtracting the knocking correction advance angle θK obtained in steps 110, 112, 118, and 120 from the basic advance angle OB, which determines the engine speed and engine load, is set as the actual ignition timing θ, and in step 124, the actual ignition timing is determined. The time at which the igniter 28 should be turned on is calculated from the time θ and the time when this task was started, and the calculated value is set in the output register provided in the output port 48, and the execution of the task is ended in step 126.

Note that in steps 118 and 120, the predetermined value 0 is set larger than the predetermined value P, so the smaller the value KNOCK(i) representing the knocking detection frequency, the larger the advance angle θ of the knocking correction (13) becomes. In this embodiment, similarly to the embodiment shown in FIG. 3, it is possible to correct changes in the ignition timing of cylinders in which knocking is difficult to detect when the engine is in production or due to changes over time. This embodiment has the same effect as the embodiment shown in FIG. 3 in terms of optimally controlling the ignition timing, but the control 1u
If the memory capacity of the path 34 is insufficient, the embodiment shown in FIG. 3 is preferable.

As explained above, in the present invention, the knocking detection frequency in the cylinder is determined, and the advance correction amount of the ignition timing of the cylinder is changed depending on the magnitude of the knocking detection frequency. Accordingly, the occurrence of knocking in the cylinder of the engine can be suppressed, and the engine output can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of the engine control device, FIG. 2 is a block diagram showing specific details of the control circuit 34, and FIG. 3 is a block diagram showing the ignition timing control task executed in the control circuit 34. Figure 4 is a flowchart showing another example of the ignition timing control task.1) 1... Engine;
14...Cylinder. 18... Notking sensor, 26... Distributor, 28... Igniter, 30...
IT discrimination sensor, 32...engine rotation speed sensor. 34...Open side 1 circuit. Agent Tatsuyuki Unuma (and 2 others) Figure 1 9th (15th)

Claims (2)

[Claims] (1) An engine ignition timing control method that detects knocking occurring in multiple cylinders using a single knock sensor installed in a specific cylinder, and controls the ignition timing of the cylinders based on the detected output. An ignition timing control method for an engine, characterized in that the knocking detection frequency in the common cylinder is determined, and the advance correction amount of the ignition timing in the large cylinder is changed depending on the magnitude of the knocking detection frequency. (2) If knocking is detected, the ignition timing is delayed in inverse proportion to the knocking detection frequency of the cylinder in question; if knocking is not detected, the ignition timing is delayed in proportion to the knocking detection frequency of the cylinder that has fired. The engine ignition timing control method according to claim 1, characterized in that the ignition timing advance correction amount of each cylinder is changed so as to advance the ignition timing.