JPS6242153B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an ignition timing control device that controls the ignition timing of an engine.

[Background of the invention]

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 predetermined 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 amount of retard phase shift with a predetermined time constant. However, in order to suppress knocking, all cylinders are retarded in the same way using a specific retard phase shift control amount, so if knocking occurs in a certain cylinder, not only the cylinder where knocking occurs, but also the other cylinders are also controlled. The retard angle is controlled uniformly depending on the amount.

In general, the occurrence of knocks in engine cylinders differs due to slight structural differences, variations in component parts, differences in air-fuel mixture distribution between cylinders, and the like. That is, the ignition timing at the knock limit is different 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 it is not always the case that all cylinders are ignited at the ignition timing at the knock 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.

By the way, in this type of feedback control, including the 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 of control is always beyond the knock limit, large knocking occurs at the start of control. 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 later than the optimal ignition timing at the knock limit, and it will not be possible to control all cylinders to the optimal ignition timing in 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 the operating ranges that require knock suppression by changing the magnitude of the feedback control amount, a wide dynamic range is required, and it is possible to accurately control the ignition timing over all operating ranges. It was difficult to control.

Incidentally, the occurrence of knocking depends on the ignition timing, air-fuel 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 is This value 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 high 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.

[Summary of the invention]

This invention stores a correction control value that gives an average value of the knocking limit of each cylinder in each operating state of the engine, and performs sequential correction obtained by calculating from this correction control value and a knocking signal generated for each cylinder. The reference control value in each operating state of the engine is corrected for each cylinder using a correction value obtained by combining the values, and the above correction control value is applied to each cylinder at a predetermined period to deal with the long-period change factors mentioned above. By updating based on the sequential correction value, knocking can be suppressed accurately with a small number of sequential correction values, and the response of knocking suppression control when operating conditions change is improved, allowing the ignition timing of each cylinder to be adjusted to all operating conditions. The object of the present invention is to provide a device for controlling individual knock limits.

[Embodiments of the invention]

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. Among them, the reference control value of the corresponding address is read out.
The storage means 6 has an area for storing corrected control values in two-dimensionally partitioned addresses corresponding to the rotation speed and load condition, and the read correction control values (memory correction values) are stored in the correction value calculation means. Sent on 7th. The correction value calculation means 7 inputs the cylinder identification signal of the cylinder identification means 4 and the knocking signal detected by the knock detection means 5, calculates a sequential correction value for suppressing knocking of each cylinder from these signals, and uses the obtained value to calculate the knocking suppression correction value for each cylinder. By correcting the stored correction value, an ignition timing correction value is created and output to the control value calculation means 8. Here, the sequential correction value for each cylinder is updated in the retard direction if knocking occurs, and in the advance direction if knocking does not occur. The correction value can be used not only for correction on the retard side but also on the advance side.
Further, the correction value calculation means 7 calculates an average sequential correction value from the sequential correction values of each cylinder every predetermined engine operation period, corrects the correction value, and updates and stores the result in the corresponding storage area. The control value calculation means 8 corrects the previously read reference control value with the ignition timing correction value created by the correction value calculation means 7 corresponding to the cylinder to be ignited this time, determines the ignition timing, and then adjusts the ignition timing to the ignition timing. The ignition is performed at the ignition timing determined in step 9.

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 12 generates a signal 11a having an angle of 180°; 12 a pressure sensor 12 detects the intake pipe pressure of the engine and generates a signal 12a corresponding to the pressure; 13;
14 is an analog/digital (A/D) converter that converts the signal 12a output from the pressure sensor 12 into a digital signal 13a, and 14 is an acceleration device that is attached to the engine and detects the vibration acceleration of the engine and outputs the signal 14a. sensor, 15 is acceleration sensor 14
a discriminator 16 for discriminating the period in which engine knocking has occurred from the signal 14a and outputting a signal 15a;
is an A/D converter which digitizes the signal 15a of the discriminator 15 into a signal 16a. 20 is a microcomputer, which includes a microprocessor (CPU) 21 and memory (ROM and RAM) 22.
and an interface (I/O) 23. 18 is a timing conversion circuit that converts the ignition timing control amount signal 23a calculated by the microcomputer 20 into a timing signal 18a, and 17 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 angle detector 10 becomes "L" level at 90 degrees BTDC of the first cylinder according to the rotation of the engine, and 4 cylinder
It becomes “H” level at BTDC90°. Further, the signal 11a of the angle detector 11 is a signal delayed by 180 degrees in terms of crank angle with respect to the signal 11a of the angle detector 11. These two signals 11a and 12a are connected to the interface 23 of the microcomputer 20.
is input. The pressure sensor 12 detects the intake pipe pressure of the engine and generates a signal 12a at a voltage level corresponding to the pressure. Here, 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 known 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 digitized by the A/D converter 13 and inputted to the interface 23 as a signal 13a.

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, further integrates it,
Signal 15a having a level corresponding to knocking strength
Output. This signal 15a is sent to the A/D converter 16
The signal is digitized into a signal 16a and read into the CPU 21 via the interface 23. Further, the discriminator 15 is configured by the microprocessor 2
Signal 23 from interface 23 with command 1
The integral value is reset by b and initialized for the next knocking detection.

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

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, and outputs the signal 18a from the timing converter 18 at the determined ignition timing, thereby igniting the ignition. The circuit 17 ignites the engine.

A flowchart of the processing executed by the CPU 21 is shown in FIG. P ₁ to _{P 39} in the figure indicate each 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, fourth, and second 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 first and second 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 , the time interval from the previous processing start time to the present time, that is, the period corresponding to a crank angle rotation of 180° is measured. _P3 converts this measured period into the number of rotations. Input the pressure signal in P ₄ , and calculate the engine load condition from this signal in P ₅ .

At _P6 , the state of the signal 10a of the angle detector 10 is checked. If the status is "L", the cylinder that was ignited just before is the first cylinder or the second cylinder, as shown in Figure 3.
It is a cylinder. Next, in _P7 , the state of the signal 11a of the second angle detector 11 is checked, and if the output state is "L", the immediately preceding ignition cylinder is identified as the first cylinder, and in _P8 , the ignition cylinder is identified. In order to store information, a number 1 indicating the firing order of the first cylinder is stored in a register n provided in the memory 22. Signal 11a at P ₇
If the state is "H", the number 4 indicating the firing order of the second cylinder is stored in the register n at _P9 . On the other hand, P ₆
If it is determined that the signal 10a of the first angle detector 10 is "H", the immediately preceding ignition cylinder is the third one.
cylinder or the fourth cylinder. Below, P ₁₀ is P ₇
Similarly, check the state of the signal 11a of the angle detector 11, and if it is "L", store the number 2 indicating the firing order of the third cylinder in the register n at _P11 , and if it is "H"
At P ₁₂ , enter the number 3 in register n indicating the firing order of the 4th cylinder.
to remember.

At P ₁₃ , the knocking signal 16a (Δ
After reading K), a signal 23b for resetting the integral value of the discriminator 15 is generated to prepare for detecting the next occurrence of knocking. At _P14 , it is checked whether the read signal 16a (ΔK) is 0, that is, whether knocking has occurred in the cylinder due to the previous ignition. If there is no knocking, registers are first updated in _P6 to _P15 among the registers for sequentially updating correction values provided corresponding to each cylinder.
1 is added to the value of the register D(n) corresponding to the immediately previous ignition cylinder identified in _P12 , and this value is stored again in the register D(n). Next, at P ₁₆ , check whether the value of this register D(n) has reached 10 or not.
In other words, during the period of 10 consecutive ignitions of the relevant cylinder, the signal 16a is activated.
Detect whether or not (ΔK) is 0, and D(n)=
If the value is 10, in _P17 , the value of the register C(n) storing the sequential correction value of the cylinder is subtracted by 1, and this value is stored. At _P18 , the value of the register D(n) which performs the above counting operation is reset to 0 in preparation for the next 10 ignition counting operations. on the other hand,
In P ₁₆ , if D(n)≠10 and the number of consecutive ignitions has not reached 10, the register C for sequential correction value storage
The value of (n) is not subtracted, but is kept as it is and proceeds to the next step 21.

Also, if there is signal 16a at P ₁₄ (Δ
K≠0), ΔK is added to the value of the register for storing correction value C(n) in P ₁₉ , and the correction value increases by the amount corresponding to the knocking strength, and then in the next P ₂₀
Now, reset the value of the register D(n) for counting the number of ignitions and prepare for the 10 ignition measurement operation.

Therefore, the value of the successive correction value storage register C(n), which increases or decreases depending on the knocking state, is the knocking intensity when it is determined that there is knocking based on the signal 16a detected every ignition of the relevant cylinder. The value is updated in an increasing direction according to the amount. If there is no knotting, 1 for every 10 ignitions of the relevant cylinder.
only update its value in a decreasing direction. In this case, the range of change is set so that it can take either a positive or negative value with zero as its center. Note that the count of 10 ignitions that determines the gain in the decreasing direction is one example, and is not limited to this.

In this way, when the correction value of the cylinder in which knocking has occurred is updated in response to the signal 16a caused by the previous ignition, the process of updating the stored correction value stored in the learning map is then started from _P21 onwards.

At _P21 , the memory correction value stored at the corresponding learning map address is read into the B register from the rotational speed and load condition determined at _P3 and _P5 . next,
In P ₂₂ , compare the engine speed at the start of counting in engine steady state counting register E, which will be described later, and the engine speed obtained in P ₃ , and if the difference is 50 rpm or more, it is determined that the engine speed has changed. Jump to processing P ₃₁ . If the change is less than 50 rpm, it is determined that the engine is operating at a constant rotation speed, and in the next step _P23 , the change in the load state from the time when register E starts counting is similarly checked. If the change in load condition is 5% or more, it is assumed that a change has occurred in the operating condition of the engine and the process proceeds to _P31 .
On the other hand, if the change is less than 5%, it is determined that the vehicle is being operated under a constant load condition and the process proceeds to _P.24 . At _P24 , 1 is added to the value of register E that counts the steady operating state of the engine. In P ₂₅ , check whether the count value of this register E is 100 or not, that is, 100 consecutive
Check to see if the engine has been operating at a constant speed and steady load throughout the ignition period. If 100 ignitions have not been reached, proceed to page ₂₈ . E
If =100, the process proceeds to _P26 , where the average value of the sequential correction values for each cylinder is calculated and stored in register F. In the next step _P27 , the average value of the sequential correction values is added to the stored correction value previously read out from the learning map in _P21 and stored in the B register, and the result is stored in the B register again. At _P28 , the changed value of the B register is updated and stored in the corresponding storage area on the learning map. At _P29 , the average value F of the sequential correction is subtracted from the sequential correction value of each cylinder to update the sequential correction value of each cylinder. In P ₃₀ , in preparation for the next update of the stored correction value, the steady state counting register E is cleared, the engine speed and load condition at this point are stored as standards for determining the steady state, and the process proceeds to P ₃₃ .
On the other hand, if it is determined in P ₂₂ or P ₂₃ that there is a change in the engine operating state, the steady state counting register E is cleared in P ₃₁ , and the engine speed and load state are used for steady state determination from the next ignition. Memorize it as a standard.
At _P23 , since the sequential correction values for each cylinder in the operating state before the change are meaningless in the operating state after the change, they are all set to 0 and the process proceeds to _P23 . In this way, the stored correction value on the learning map is updated when the engine continues to operate in a steady state for 100 ignitions. The update is performed in such a way that the average value of the successive correction values for knocking suppression performed for each cylinder is always zero. That is, the stored correction value is updated so that the sequential correction value for each cylinder corrects only the dispersion of the knock limit of each cylinder from the average value.

Further, when the engine is not in a steady state, updating of the correction value is prohibited, and meaningless updating of the correction value in the knocking suppression state before the engine operating state changes is prevented.

In addition, in updating this correction value, it is determined that the engine is in a steady state when the fluctuation in the engine speed is less than 50 rpm and the load fluctuation is less than 5%, but this is just one example, and the determination conditions may be something else. Further, the number of engine ignitions is counted, and when the number reaches a predetermined number, the correction value is updated, but this update may be performed every predetermined time period.

Now, when the process of updating the memory correction values on the learning map is completed in this way, the process of determining the ignition timing of the cylinder to be ignited this time begins.

At _P33 , in order to identify the cylinder to be ignited this time, 1 is added to the previously determined ignition order n of the cylinders that were ignited last time. That is, for example, if the previous ignition was in the first cylinder, the value of register n is 1, and by adding 1 to this, the value of register n becomes 2,
The cylinder with the corresponding firing order is the third cylinder.
At _P34 , it is checked whether the value of register n has become 5 by the operation at _P33 . If n=5, the previous ignition cylinder was the second cylinder, and this time it is the first cylinder in the ignition order, so the value of the register n is set to 1 at _P25 . This process determines the current ignition cylinder. Correction of the contents of register B that stores the correction value in P ₃₆ (read from the learning map in P ₂₁ , and if the process of P ₂₆ to _{P 30} is passed, the updated correction value is stored) value and sequential correction value register C corresponding to the cylinder to be ignited this time.
(n) (if updated in P ₂₉ , the updated value) is added to create the ignition timing correction value. In P ₃₇ ,
Read out the reference control value at the address on the advance angle map that corresponds to the rotation speed and load condition found in P ₃ and P ₅ , and then proceed to P _36.
Subtract the ignition timing correction value found in step 1 to create a control value that determines the ignition timing of the cylinder to be ignited this time.

The control value of this calculation result is data that indicates the ignition position as a value equivalent to the angle, and in P ₃₉ , this data is expressed as the delay time from the output reversal time of the angle detector 10 or 11 (the counter count start time in P ₁ ). Convert to data. This angle-to-time conversion calculation is easily possible based on period information in _P2 .

The ignition timing control value converted to time at P ₃₉ is set to the latch of timing converter 18.

The timing converter 18 has a counter, and this counter starts counting when the microcomputer 20 starts arithmetic processing, that is, when the output state of the first or second angle detector 10, 11 is reversed. When the value of this counter matches the value of the latch set in P ₃₉ , the timing converter 18 generates an ignition signal, de-energizes the ignition coil of the ignition circuit 11, and controls the microcomputer 2.
The engine is ignited at the ignition timing determined by 0.

In this way, this embodiment determines the steady operating state of the engine, and in the steady state, stores the correction value that provides the ignition timing at the knock limit of each cylinder at the address corresponding to the engine operating state on the learning map as a correction value. , by creating a sequential correction value for each cylinder using the knocking signal detected for each ignition, and correcting the standard ignition timing for each cylinder using this sequential correction value and the above-mentioned memory correction value, Enables control of ignition timing to the limit. On the other hand, during engine transient operating conditions, updating of the memory correction value is prohibited, and the ignition timing of each cylinder is corrected using the correction value already determined under steady state conditions. Even when the state changes, the ignition timing of each cylinder is controlled to the average ignition timing of the knock limits of each cylinder under the changed operating state. That is, since only the variation in the knocking limit between cylinders is corrected by the sequential correction value created by the knocking signal, the responsiveness of the feedback control of the ignition timing is very good.
Furthermore, the sequential correction value for each cylinder only needs to correct the variation from the average of the ignition timing that gives the knock limit for each cylinder, so the control range is narrow.
That is, it is possible to improve control accuracy without requiring a wide dynamic range.

In addition, since the correction value on the learning map and the sequential correction value for each cylinder can take values of both positive and negative polarity, it is possible to control the ignition timing to the advanced side beyond the standard ignition timing. Even if the ignition timing of the cylinder is set to the retard side than the ignition timing of the knock limit, the memory correction value is updated in the advance direction, and the operation at the ignition timing of the knock limit of each cylinder is performed in all operating conditions. It becomes possible.

In this embodiment, when updating the correction value, the update amount of the correction value is created by simply arithmetic averaging the sequential correction values of each cylinder. Create the update amount using a method such as weighting and averaging according to the polarity,
The stored correction value may be updated. Further, in this embodiment, the cylinders are identified based on the output states of the two angle detectors, but the method is not limited to this method. For example, a detection means for identifying the standard ignition timing may be provided to sequentially count the ignitions. Even if there is a method for identifying cylinders, the essence of the present invention is not affected in any way.

〔Effect of the invention〕

As described above, according to the present invention, the reference ignition timing of the engine is set in advance in accordance with each operating state, and the difference between this reference ignition timing and the actual knock limit ignition timing of each cylinder is is obtained from the knocking signal, and the average value of this difference 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. By absorbing variations in the ignition timing at the knock limit due to aging, etc., and suppressing knocking that occurs in a short period of time with a small sequential correction amount using the knocking signal, the knocking suppression by ignition timing control is highly accurate. I can do it well. In addition, even if the engine operating condition changes, the ignition timing of each cylinder is quickly controlled to the average ignition timing of the knock limits of each cylinder, preventing the occurrence of large knocks during transients and engine performance due to transient retardation. This prevents a decrease in Furthermore, since the standard ignition timing can be corrected to the advanced side, even in operating modes where the standard ignition timing is set to the retarded side with respect to the ignition timing at the knock limit, each cylinder can be adjusted to the standard ignition timing. While the actual control ignition timing is controlled to the advanced side with respect to the timing, feedback control can be performed individually using the knocking signal. Therefore, under all operating conditions, each cylinder is controlled by the optimum ignition timing at the knock limit, and it is no longer necessary to set the reference ignition timing on the advanced side with respect to the ignition timing at the knock limit. For example, by setting the reference ignition timing with the center value of the knock limit of each cylinder as the target, it is possible to prevent the 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, and means for generating a reference control value that provides reference ignition timing characteristics for each operating state of the engine; cylinder identification means for identifying an ignition cylinder of the engine; means for generating a sequential correction value for ignition timing based on the output of the knock detection means for each cylinder identified by the cylinder identification means; The correction control value obtained by calculating the sequential correction value of each cylinder in the state at a predetermined period is updated and stored at an address corresponding to each operating state of the engine, and corresponding is performed based on the detection output of the operating state sensor. a memory means from which the stored value of the address is read; a control value calculating means for calculating the read stored value and the above-mentioned sequential correction value for the cylinder to generate an ignition timing correction control value for the cylinder; An engine ignition timing control device comprising determining means for determining the ignition timing of each cylinder based on the output of the calculating means and a control value calculated from the reference control value.