JPS6244096B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for controlling the ignition timing of an engine.

In general, it is known that, in terms of output and fuel consumption characteristics, an engine is most efficient when operated at an ignition timing in which slight knocking occurs (knock limit).

This type of conventional device retards the ignition signal, which is generated based on preset reference ignition timing characteristics, by a fixed angle each time knocking occurs, or by a predetermined angle depending on the knocking intensity. In some cases, when there is no occurrence, the ignition timing is feedback-controlled to the ignition timing at the knock limit by decreasing the retard phase shift amount by a predetermined number of times.

However, in order to suppress knocking, all cylinders are retarded in the same way with a specific retard phase shift control amount, so if knocking occurs in a certain cylinder, not only the cylinder in which it occurred will be affected, but other cylinders will also be affected by the controlled amount. Therefore, the angle is uniformly retarded.

In general, each cylinder of an engine has a different knocking situation due to slight structural differences, variations in component parts, differences in air-fuel mixture distribution between cylinders, etc. In other words, the knocking limit ignition timing differs for each cylinder. .

Therefore, if a conventional device that performs such control is used, the ignition timing is set to the knock limit of the cylinder where knocking is most likely to occur. this is,
Ignition timing control is not necessarily optimal for the engine, and all cylinders are not ignited at the ignition timing limit.

Therefore, several proposals have been made for cylinder-specific ignition timing control devices that perform feedback control of the ignition timing retardation phase shift control amount for each cylinder.

In this type of feedback control, including control for each cylinder, the control for suppressing knocking is to control the amount of retardation from the reference ignition timing. For this reason, the reference ignition timing must be set in advance at a point that is more advanced than the knock limit. Therefore, since the ignition timing at the start point of control is always beyond the knock limit, a large knock occurs at the start of control. Therefore, it is desirable to set the reference ignition timing to an ignition timing that is slightly ahead of the knock limit. However, if the above-mentioned variation in the knock limit between cylinders is also taken into consideration, such setting is practically impossible. Under certain operating conditions, it is inevitable that the reference ignition timing will be set on the delayed side with respect to the ignition timing at the knock limit. In engine operating conditions set to the delayed side, the engine will ignite at a later time than the optimum ignition timing at the knock limit, making it impossible to control all cylinders to the optimum ignition timing across all operating conditions. .

In addition, with conventional devices, even if the operating state of the engine changes, the ignition timing that was before the change in operating state is applied as is, so there is a large time lag before the control amount settles to the control target value in the operating state after the change. Get out. That is, the response to changes in operating conditions was poor. Furthermore, since the control device controls all operating ranges that require knock suppression by changing the magnitude of the feedback control amount, a wide dynamic range is required and ignition timing can be controlled accurately over all operating ranges. It was difficult to do so.

By the way, the occurrence of knocking depends on the ignition timing air-twist ratio, intake air temperature, intake air humidity, and many other factors among the operating characteristics of the engine. However, things that depend on changes in natural conditions, such as intake air temperature and intake air humidity, have very long cycles of change, such as one day or one season. Therefore, changes in the occurrence of knocking due to these changes also occur over a long period. In other words, the knocking that occurs in a short period of time under the same operating conditions is approximately the same level, and there is no significant difference in the frequency and intensity of the knocking. In other words, since the correction control value required to suppress knocking that occurs under the same operating condition is almost the same in a short period of time, the previously stored correction control value will be is controlled as the current correction control value, and the ignition timing correction range only needs to be narrow in case of slight knocking occurring during control. Knocking can be suppressed with precision and responsiveness, and ignition timing can be controlled to the knock limit. The above-mentioned long-period change factors can be corrected by slowly changing the correction control value.

This invention stores a correction control value for each cylinder in each operating state of the engine, and uses a correction value that combines this correction control value and a sequential correction value obtained by calculating from a knocking signal generated for each cylinder to control the engine. The reference control value in each operating state is corrected for each cylinder, and in response to the long-period change factors mentioned above, the correction control value for each cylinder is updated at a predetermined period based on the sequential correction value for each cylinder. By doing so, knocking can be suppressed accurately with small sequential correction values, and the response of knocking suppression control when driving conditions change can be improved.
It is an object of the present invention to provide a device for controlling the ignition timing of each cylinder to its individual knock limit over all operating conditions.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the general configuration of the present invention. The rotation speed detection means 1 detects the rotation speed of an engine (not shown), and the load detection means 2 detects the load state of the engine. The reference control value generating means 3 has a memory, and the reference control value for providing the reference ignition timing characteristic is stored in advance at addresses two-dimensionally partitioned according to the engine speed and load condition by the means 1 and 2. The reference control value of the corresponding address is read out. The storage means 6 corresponds to each cylinder of the engine,
It has an area for storing correction control values at addresses divided two-dimensionally according to the rotation speed and load condition, and information on the cylinder to be ignited this time from the cylinder identification means 4 and current rotation speed information from the rotation speed detection means 2. Then, the correction control value (memory correction value) is read from the address specified by the load state information from the load detection means 2 and sent to the correction value calculation means 7. The correction value calculation means 7 calculates knocking control sequential correction values for each cylinder from the cylinder information of the cylinder identification means 4 and the knocking signal detected by the knock detection means 5, and calculates the stored correction value as the result value. By performing the correction, an ignition timing correction value is created and output to the control value calculation means 8. Further, when knocking occurs during a predetermined engine operation period, the correction value calculation means 7 updates and stores the memory correction value for the relevant cylinder to a value on the retard side, and when knocking does not occur, the correction value is updated to a value on the retard side and stored. Update and store the value on the corner side. The control value calculating means 8 corrects the reference control value read out using the ignition timing correction value created by the correction value calculating means 7 for the cylinder to be ignited this time, determines the ignition timing, and outputs the ignition timing to the ignition means 9. Ignition is performed at the determined ignition timing.

FIG. 2 is a block diagram showing an embodiment of the present invention applied to a four-stroke, four-cylinder engine. In the figure, reference numeral 10 denotes an angle detector which generates a signal 10a whose signal level is inverted every 360 degrees of rotation angle of the crank in conjunction with the rotation of the camshaft of the engine, and 11
is the phase difference with respect to the signal 10a of the angle detector 10.
An angle detector that generates a signal 11a having an angle of 180 degrees, 12 a pressure sensor that detects the intake pipe pressure of the engine and generates a signal 12a corresponding to the pressure, and 13 a digital signal that outputs the signal 12a from the pressure sensor 12. An analog/digital (A/D) converter 14 is attached to the engine and detects vibration acceleration of the engine and outputs a signal 14a. 15 is an acceleration sensor that converts the signal 14a of the acceleration sensor 14 into an engine signal 13a. a discrimination detector 1 for discriminating a period in which knocking has occurred and outputting a signal 15a;
6 is an A/D converter which digitizes the signal 15a of the discriminator 15 into a signal 16a. 20 is a microcomputer, which mainly includes a microprocessor (CPU) 21 and memory (ROM and RAM).
22 and an interface (I/O) 23. 18 is microcomputer 2
a timing conversion circuit 17 that converts the signal 23a of the ignition timing control amount calculated at 0 into a timing signal 18a;
is an ignition circuit that ignites the engine using the timing signal 18a generated by the timing conversion circuit 18.

Next, the operation of this embodiment configured as described above will be explained. FIG. 3 is an output waveform diagram of the angle detectors 10 and 11 shown in this embodiment, and the signal 10a of the first angle detector 10 follows the rotation of the engine, and the signal 10a of the first angle detector 10 follows the rotation of the engine.
When the cylinder's BTDC is 90°, the level becomes "L", and when the 4th cylinder's BTDC is 90°, it becomes the "H" level. Further, the signal 11a of the angle detector 11 is the signal 1 of the angle detector 11.
The signal is delayed by 180 degrees in crank angle relative to 1a. These two signals 11a and 12a are input to the interface 23 of the microcomputer 20. A pressure sensor 12 detects the intake pipe pressure of the engine, and outputs a voltage level signal 12 corresponding to the pressure.
generate a. Since the intake pipe pressure of the engine changes sensitively in response to the load state of the engine, the load state of the engine can be determined from the level of the signal 12a obtained by detecting this intake pipe pressure. Now, the signal 12a generated from the pressure sensor 12 is
The signal 13 is digitized by the D converter 13.
a and is input to the interface 23.

On the other hand, the acceleration sensor 14 is attached to the engine and constantly detects vibrations of the engine. The signal 14a, which is the detection output, contains a noise signal caused by mechanical vibration caused by engine operation and a knocking component caused by vibration caused by knocking of the engine. The discriminator 15 discriminates and detects the knocking component from the signal 14a, performs further integration, and outputs a signal 15a having a level corresponding to the knocking intensity. This signal 15a is digitized by the A/D converter 16 to become a knocking signal 16a, which is read into the CPU 21 via the interface 23. Further, the discriminator 15 is operated by a microprocessor 21.
The signal 23b from the interface 23 is
The integral value is reset and initialized for the next knocking detection.

The memory 22 of the microcomputer 20 is
It has ROM and RAM, and the ROM is an area (hereinafter referred to as advance angle) that stores reference control values that give reference ignition timing characteristics in each operating state of the engine at predetermined addresses corresponding to the engine speed and load state. The RAM is provided with a memory correction map for each cylinder in the operating state corresponding to each address, which is determined corresponding to each cylinder of the engine, the engine speed, and the negative state. An area (hereinafter referred to as a learning map) for storing values is provided.

The CPU 21 determines the optimal ignition timing for each cylinder from the sensor information of the angle detectors 10, 11, the pressure sensor 12, and the acceleration sensor 14, outputs the signal 18a from the timing converter 18 at the determined ignition timing, and outputs the signal 18a to the ignition circuit. 17 to ignite the engine.

A flowchart of the processing executed by the CPU 21 is shown in FIG. P ₁ to _{P 33} in the figure indicate each process execution step of the flowchart.

Note that this flowchart shows the case of a four-cylinder engine in which ignition is performed in the order of the first, third, second, and fourth cylinders.

The control calculation by the CPU 21 is performed once per ignition cycle.
This is performed in synchronization with the timing at which the states of the output signals of the angle detectors 10 and 11 are reversed.

First, at _P1 , the counter of the timing conversion circuit 18 is reset to 0 and a counting operation is started.
At _P2 , measure the time interval from the start of the previous process to the current time, that is, the period corresponding to a rotation of 180 degrees in terms of crank angle. In P ₃ , this measured period is converted into the number of revolutions. Input the pressure signal in P ₄ , and calculate the engine load condition from this signal in P ₅ . At _R6 , the address of the advance angle map corresponding to the rotational speed and load condition calculated at _P3 and _P5 is specified, the corresponding reference control value data is read out, and stored in the A register.

At _P7 , the state of the signal 10a of the angle detector 10 is checked. If the state is "L", as shown in FIG. 3, the cylinder that was ignited immediately before is the first cylinder or the second cylinder. Then, at P ₈ , the second angle detector 11
Check the state of the signal 11a and check that the output state is “L”
If so, the immediately preceding ignition cylinder is identified as the first cylinder, and in order to store the ignition cylinder identification information in _P9 ,
A number 1 indicating the firing order of the first cylinder is stored in a register n provided in the memory 22. Signal 11 at _P8
If the state of a is "H", the number 4 indicating the firing order of the second cylinder is stored in register n at _P10 . on the other hand,
At P ₇ , the signal 10a of the first angle detector 10 is “H”
If it is determined that the ignition cylinder immediately before is
Either cylinder or 4 cylinder. Thereafter, in P ₁₁ , the state of the signal 11a of the angle detector 11 is checked in the same way as in P ₈ , and if it is "L", the number 2 indicating the firing order of the second cylinder is stored in the register n in P ₁₂ , and the state is "H". In this case, the number 3 indicating the firing order of the fourth cylinder is stored in the register n at _P13 .

At P ₁₄ , knocking signal 16a (Δk)
is read, and a signal 23b for resetting the integral value of the discriminator 15 is generated at _P15 to prepare for detecting the next occurrence of knocking. In _P16 , the value of the register C(n) corresponding to the cylinder identified in _P7 to _P13 is input in _P14 among the sequential correction value storage register group provided in the memory 22 corresponding to each cylinder. The resulting knocking signal 16a (Δk) is corrected and stored in C(n) again. In P ₁₇ , compare the rotation speed at the time when the engine steady state counter (described later) starts counting and the rotation speed obtained in P ₃ , and if the difference is 50 rpm or more, it is assumed that the engine rotation speed has changed and proceed to P ₂₆ . Below 50 rpm, the engine is considered to be running at a constant speed. Subsequently, in _P18 , the variation in the load state from the time when counting starts is similarly checked. If the change in load condition is 5% or more, it is assumed that the operating condition of the engine has changed and the process proceeds to _P26 . Load condition change 5%
If the value is less than 1, it is assumed that the load is constant. At _P19 , 1 is added to the value of the register D(n) of the corresponding cylinder among the registers that count the engine speed and load state. At _P21 , it is checked whether the count value of this register D(n) is 100, that is, whether the cylinder in question has been operated in the above-mentioned constant operating state for 100 consecutive ignition cycles. If the number has not reached 100, no processing is performed and the process proceeds to P ₂₈ . If D(n) = 100, first in P ₂₁
Check whether the sequential correction amount C(n) for the cylinder in question created in _P16 is 0. If C(n) = 0, no knocking has occurred in the cylinder during 100 consecutive ignitions, so P _{3 and}
Read out the memory correction value B(n) on the corresponding learning map from the number of revolutions and load condition obtained in P ₅ and the cylinder information identified in P ₇ to P ₁₃ , subtract 1 from this, and return B(n). n). If C(n)≠0, assuming that knocking occurs during these 100 consecutive ignitions, the correction value C(n) is sequentially added to the memory correction value B(n) on the corresponding learning map at _P23 .
is added and stored in B(n) again, and the previous sequential correction value C(n) is set to 0 (initialized) at _P17 . Next, in P ₂₅ , in preparation for the next update of the memory correction value B(n), the value of the register D(n) for counting the number of ignitions is cleared, and the engine speed and load condition at this point are used to determine the steady operating state. memorize it as a standard for On the other hand, if it is determined in P ₁₇ or P ₁₈ that there is a change in the engine operating condition, in P ₂₆ the sequential correction value created in the operating condition before the change is regarded as meaningless and this sequential correction value is stored. Clear the value of register C(n). In the next P ₂₇ , the register D for counting the number of ignitions is set as in P ₂₅ .
(n) is cleared, the current engine speed and load condition are stored, and initialization is performed for updating the stored correction value.

In this way, the correction values on the learning map are determined when the steady engine operation is 100 ignition revolutions for each cylinder.
Updated if retained. If no knocking occurs during 100 ignition cycles, the stored correction value is deemed to be excessive and is updated in a decreasing direction. This correction value does not need to be a particularly positive value, and can be a negative value if knocking does not occur continuously. On the other hand, when the occurrence of knocking is detected, the correction value is updated in the increasing direction. Furthermore, when the engine is not in a steady state, updating of the correction value is prohibited, thereby preventing meaningless updating of the stored correction value due to knocking that occurs before the operating state of the engine changes.

Now, when the process for the knocking that occurred in the previous ignition is completed as described above, the process begins to determine the ignition timing of the cylinder to be ignited next.

At _P28 , 1 is added to the ignition order n of the previously ignited cylinders determined at _P7 to _P13 in order to designate the cylinder to be ignited next. That is, for example, the previous ignition was
For a cylinder, if the value of register n is 1, add 1 to this.
By adding , the value of the register n becomes 2, so the cylinder in the ignition order corresponding to this becomes the third cylinder. At _P29 , it is checked whether the value of register n has become 5 by the operation at _P28 . If n=5, the previous ignition cylinder was the second cylinder, and the next ignition order will be the first cylinder, so the value of the register n is set to 1 at _P30 .

When the next ignition cylinder is determined in this way,
In P ₃₁ , the rotation speed obtained in P ₃ and P ₅ and the correction value B of the cylinder to be fired next in the loaded state
(n) is read from the learning map, and this value is added to the successive correction value of the cylinder to be ignited next to create an ignition timing correction value. In P ₃₂ , the reference control value A is read from the address on the advance angle map based on the rotational speed and load condition obtained in P ₃ and P ₅ , and the ignition timing correction value B obtained in P ₃₁ is subtracted from it, and the value of the next cylinder to be ignited is calculated. Create control values that determine ignition timing.

The control value resulting from this calculation is data indicating the ignition position by a value corresponding to the angle. At _P33 , this data is converted into delay time data from the inversion time of the output of the angle detector 10 or 11 (the time at which the counter starts counting at _P1 ). This is easily possible based on the period information in calculation _P2 of this angle-time conversion.

At P ₃₃ , the ignition timing control value converted to a time signal is set into a latch within the timing converter 18.

Timing converter ¥18 counter is CPU2
Counting starts at the start of the calculation process in step 1, that is, when the state of the output of the angle detector 10 or 11 is reversed, and when this count value matches the latch value set in _P33 , the timing converter starts counting. 18 generates a signal 18a, the ignition circuit 17 cuts off the power to the primary side of the ignition coil, and the microcomputer 2
The engine is ignited at the ignition timing determined in 0.

In this way, this embodiment determines the steady operating state of the engine, and stores correction values in the learning map provided for each cylinder so that the sequential correction value for each cylinder becomes a small value in the steady operating state. By updating and correcting the reference ignition timing for each cylinder using the stored correction value and a slight sequential correction value, ignition can be performed at the ignition timing of each cylinder's individual knock limit. On the other hand, updating of the memory correction value is prohibited in the transient operating state of the engine.
Ignition is configured to ignite at an ignition timing that is a reference ignition timing that has been corrected using a stored correction value that has already been found in a steady state. Therefore, even if the operating condition of the engine changes, the ignition timing of each cylinder is quickly controlled to the ignition timing of the individual knock limit, and the responsiveness of the ignition timing feedback control using the knocking signal is very good. Since the control range may be narrow, control accuracy is improved. In addition, since the memorized correction value of the learning map can take values of polarity on both positive and negative sides, it is possible to control the ignition timing in an advanced direction beyond the standard ignition timing, so that the standard ignition timing is not changed. Even when the ignition timing is set to the retard side than the limit ignition timing, ignition can be performed at the knock limit ignition timing by updating the stored correction value in the advance direction.

In the above embodiment, the stored correction value is updated every 100 ignitions of the relevant cylinder, but this may be done every predetermined period of time. Further, in the above embodiment, the cylinders are identified based on the output information of the two angle detectors, but the invention is not limited to this. For example, a detection means for identifying a reference ignition cylinder may be provided to sequentially count the ignitions. Even if a method such as identifying cylinders is adopted, the essence of the present invention is not affected in any way.

As described above, the present invention sets the reference ignition timing of the engine in advance in accordance with each operating state, and calculates the difference between the reference ignition timing and the actual knock limit ignition timing of each cylinder. The value of this difference is determined by feedback control using signals, and this difference value is updated and stored at a predetermined period in a read/write memory corresponding to each operating state of each cylinder of the engine as a memory correction value. The ignition timing is controlled by absorbing variations in the ignition timing at the knock limit due to change, aging, etc., and suppressing knocking that occurs within a short period of time with small sequential correction amounts using the knocking signal. Knocking can be suppressed with high precision. In addition, even if the engine operating condition changes, the ignition timing of each cylinder is quickly controlled to the ignition timing at its knock limit, preventing large knocks during transient times and deterioration of engine performance due to excessive retardation. be done. Furthermore, since the memorized correction value can also be corrected to the advanced side with respect to the standard ignition timing, even in driving modes where the standard ignition timing is set to the retarded side with respect to the ignition timing at the knock limit, each While the actual control ignition timing of the cylinders is controlled to be advanced with respect to the reference ignition timing, feedback control can be performed individually using the knocking signal. Therefore,
In all operating conditions, each cylinder is controlled to the optimum ignition timing at the knock limit, and it is no longer necessary to set the standard ignition timing to the advanced side of the ignition timing at the knock limit. By setting the reference ignition timing with the center value of the knock limit as the target, it is possible to prevent occurrence of large knocking at the start of control due to too much advancement of the reference ignition timing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the general configuration of the device of the present invention, FIG. 2 is a block diagram showing an embodiment of the device of the present invention, and FIG. 3 is a waveform diagram of the output of the angle detector shown in FIG. FIG. 4 is a flow chart of the operation of the microcomputer shown in FIG. 1...Rotation speed detection means, 2...Load detection means,
3...Reference control value generation means, 4...Cylinder identification means, 5...Knock detection means, 6...Storage means, 7
...Correction value calculation means, 8...Control value calculation means, 9
...Ignition means.

Claims (1)

[Claims] 1 knocking detection means for detecting knocking of the engine; an operating state sensor for detecting the operating state of the engine; a means for generating a reference control value that provides reference ignition timing characteristics for each operating state of the engine; A cylinder identification means for identifying the ignition cylinder of the engine, and a correction control value for the ignition timing of the cylinder identified by the cylinder identification means are stored in addresses corresponding to each operating state of the engine, and the detected output from the operating state sensor is stored in the address corresponding to each operating state of the engine. and a memory means from which a stored value is read from the corresponding address of each cylinder according to the timing, and a sequential control value for correcting the ignition timing of each cylinder based on the output of the knock detection means during a continuous predetermined operation period. If knocking occurs in the relevant cylinder, the stored value at the address corresponding to the operating state at the time of processing in the area corresponding to the cylinder in the memory means is updated to a value in the retard direction, and if knocking does not occur, is a calculation means for updating the value in the advance direction, and corrects the reference control value using the stored value read from the memory means and the value obtained by calculating the sequential correction value, and determines the ignition timing of each cylinder of the engine. An engine ignition timing control device comprising: determining means for igniting the engine at the ignition timing determined by the determining means; and ignition means for igniting the engine at the ignition timing determined by the determining means.