JPH0526941B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] The present invention reduces the lower limit permissible width of the learning value in one learning control period once the engine reaches a stable idle state, thereby reducing the This prevents engine stall due to

[Industrial application field]

The present invention relates to an improvement in an idle speed control device equipped with a learning control function, and more particularly, to a technique for preventing engine stall due to so-called foot loading during idle.

[Conventional technology]

Idle speed control, which matches the engine speed at idle with the target speed, generally reduces the air flow rate in the bypass passage that bypasses the upstream and downstream of the throttle valve if the detected engine speed is higher than the target speed. This is achieved by so-called feedback control, in which the engine speed is lowered by increasing the engine speed, and conversely, when the detected engine speed is lower than the target speed, the air flow rate in the bypass passage is increased to increase the engine speed. To explain this feedback control specifically, the detected engine speed
Calculate the correction amount α based on the difference ΔNE between NE and the target rotational speed NE ₀ , and add this to the preset basic bypass amount α ₀ to determine the control amount A = (α ₀ + α), Air is caused to flow through the bypass passage by an amount corresponding to this control amount A.

Conventionally, the engine rotation speed is made to match the target rotation speed as described above, but the following problems occur. In other words, whether or not an internal combustion engine is in an idle state is generally determined by turning the idle switch on or off. It is turned on even in the fully closed state, so if the accelerator pedal is lightly placed at idle, the throttle valve opens slightly and the engine speed increases, while the idle switch remains on. There is. In such a case, in the conventional example described above, since the idle switch is on, it is determined that the idle state is in the idle state, and control is performed to reduce the amount of bypass air to reduce the engine speed to the target speed. There was a problem in that when the accelerator pedal was released after the engine speed had fallen to the target speed, the throttle valve would be fully closed and the amount of bypass air would be small, which could cause the engine to stall.

Figure 6 shows this situation; as the throttle opening decreases as shown in Figure B, the engine speed also decreases as shown in Figure D, and when the throttle valve is almost fully closed, the idle switch is turned off. As shown in A of the same figure, the throttle opening changes from off to on, and eventually the throttle opening becomes fully closed. The amount of bypass air is shown in figure C.
In the non-idling state, it corresponds to the basic bypass amount α ₀ , and in the idling state, it corresponds to the control amount A, which is the basic bypass amount α ₀ plus the correction amount α ₁ . The amount is as follows. Then, at time t1, when the foot is lightly placed on the accelerator pedal to the extent that the idle switch is not turned off, the throttle opening becomes larger and the engine speed increases. Therefore, the difference between the engine rotation speed and the target rotation speed increases, and the correction amount α increases from α ₁ to α ₂ so as to lower the rotation speed and bring it closer to the target rotation speed. At this time, the sum of air through the throttle valve and bypass air flows into the engine, but
When the foot is released from the accelerator pedal at time t2, the throttle valve is fully closed in a short time, but the correction amount α only gradually decreases, so the air flowing into the engine becomes extremely small, resulting in engine stall. occurs.

Further, in the conventional example described above, the basic bypass amount α ₀
Since this is preset, the following problems arose. That is, since individual engines generally have different characteristics, if the basic bypass amount α ₀ is set in advance, the basic bypass amount α ₀ + may not be appropriate for that engine. In such a case, there was a problem that the engine speed could not be made to match the target speed in a short time.

In order to solve such problems, the permissible variation range of the correction amount α is limited, and the basic bypass amount is adjusted so that the control amount A and the basic bypass amount α ₀ match, that is, the correction amount α becomes zero. It has been proposed to add a learning control function to change the idle speed control device. By limiting the allowable variation range of the correction amount α, it is possible to make engine stall less likely to occur compared to the conventional example described above, and by adding a learning control function, the engine speed can be adjusted to the target speed in a short time. but can be matched to
If the so-called foot-rest, in which the driver lightly places his or her foot on the accelerator pedal, is repeated during traffic jams, the learning control function reduces the basic bypass amount α ₀ , resulting in the problem of engine stalling.

FIG. 7 is a diagram showing how the basic bypass amount α ₀ decreases due to the learning control function, and the throttle opening gradually decreases as shown in FIG.
When the idle switch becomes substantially fully open, the idle switch changes from OFF to ON as shown in FIG. Then, at time t1, when the foot is lightly placed on the accelerator pedal to the extent that the idle switch is not turned off, the throttle opening increases and the engine speed increases.
As a result, the correction amount α increases and the control amount A changes to C in the same figure.
The engine speed decreases as shown by the solid line, and the engine speed decreases to the target speed. In this case, in order to prevent the engine from stalling when the foot is removed from the accelerator pedal, the permissible variation range of the correction amount α is limited (in this case, the permissible variation range is assumed to be ΔA). , the control amount A never becomes less than A1. Further, as the control amount A decreases, the basic bypass amount (learned value) also decreases from α ₁ to α ₂ as shown by the dotted line in FIG. Furthermore, since the amount of learning during one learning control period (the period from when the idle switch is turned on until it is turned off again) is limited to prevent engine stalling (in this case, it is set to ΔG), The basic bypass amount will never be smaller than α ₂ .

Then, at time t2, when the accelerator pedal is depressed from the footrest position to start, the throttle opening gradually increases as shown in Figure B, and eventually the idle switch changes from on to as shown in Figure A. Switched off. Then, when the idle switch is switched from on to off, the control amount becomes α ₂ as shown in C in the figure.

Then, at time t3 after the throttle opening decreases and the idle switch switches from off to on, if the foot is lightly placed on the accelerator pedal to the extent that the idle switch does not turn off, the control amount A remains the same. The amount of bypass decreases as shown by the solid line in Figure C, and the basic bypass amount also decreases as shown by the dotted line. In this case as well, since the allowable variation range of the correction amount α is limited to ΔA, the control amount A is A2
Since the basic bypass amount will not become smaller than α ₃ and the amount learned during one learning control period is also limited to ΔG. However, as can be seen by comparing α ₁ and α ₃ ,
α ₃ is much smaller than α ₁ .

That is, if the driver is repeatedly put on the vehicle during a traffic jam in which starting and stopping are repeated, the basic bypass amount gradually decreases as described above, and as a result, engine stalling becomes more likely to occur.

[Problem that the invention seeks to solve]

The present invention solves the above-mentioned problems, and its purpose is to prevent an engine stall from occurring even when a foot is placed on the vehicle during traffic jams in an idle rotation control device equipped with a learning control function. It is in.

[Means for solving problems]

The present invention solves the above-mentioned problems by:
As shown in the configuration diagram of FIG. 1, there is a correction amount calculation means 1 that calculates a correction amount corresponding to the difference between the engine rotation speed and the target rotation, and a correction amount calculation means 1 that changes the learning value so that the learning value matches the control amount. a learning control means 2; a control amount calculation means 3 for calculating a control amount based on the learning value calculated by the learning control means 2 and the correction amount calculated by the correction amount calculation means 1; control means 4 for setting the amount of air supplied to the control amount to be an amount corresponding to the control amount calculated by the control amount calculation means 3;
A setting means 5 for setting a lower limit permissible range of variation of the learned value in one learning control period, and a detecting means 6 for detecting that the engine has reached a stable idle state, and the detecting means 6 detects when the engine Before detecting that the engine has entered a stable idle state, the lower limit fluctuation permissible range set by the setting means 5 is set as the first permissible range, and the detecting means 6 detects that the engine has entered a stable idle state. Thereafter, the lower limit fluctuation permission range set by the setting means 5 is set to a second permission width smaller than the first permission width.

[Effect]

In the present invention, once the engine reaches a stable idle state, the permissible variation range of the learned value is made small, thereby preventing engine stalling due to foot rest. In other words, once the engine reaches a stable idle state, there is no need to change the learning value significantly, so even if the lower limit of the learning value is made smaller, the learning control function will not be impaired. Therefore, by doing as described above, it is possible to prevent engine stall due to foot rest without impairing the learning control function.

〔Example〕

FIG. 2 is a block diagram of an embodiment of the present invention.
Reference numeral 1 denotes a microprocessor, and 22 stores a control program for causing the microprocessor 21 to perform predetermined operations, a target rotational speed NE ₀ , etc.
ROM, 23 is RAM, 24 is an input/output unit, 25 is an air cleaner, 26 is a pipe, 27 is a throttle valve, 28 is a surge tank, 29 is an engine, 30
3 is a muffler, 31 is a bypass passage, 32 is a control valve, 33 is an idle switch, 34 is a rotation speed sensor such as a crank angle sensor that detects the rotation speed of the engine 27, 35 is a standby RAM, 3
6 is an ignition switch, 37 and 38 are constant voltage circuits, and 39 is a battery. Here, since the standby RAM 35 is supplied with operating voltage from the constant voltage circuit 38 without going through the ignition switch 36, it retains its memory contents even after the ignition switch 36 is turned off. It is possible.

The intake air is cleaned by an air cleaner 25 and guided to a conduit 26, a part of which is guided to a surge tank 28 via a bypass passage 31, and the rest to the surge tank 28 via a throttle valve 27.
After being mixed with fuel in the surge tank 28, the exhaust gas is led to the engine 29, where it explodes and burns, and the exhaust gas is discharged to the outside via the muffler 30. still,
The flow rate of air flowing through the bypass passage 31 is adjusted by a control valve 32 whose opening degree is controlled by a control signal applied from the microprocessor 21 via the input/output section 24.

Further, FIG. 3 is a flowchart showing the processing contents of the microprocessor 21, and the operation of FIG. 2 will be explained below with reference to the same figure.

When the supply of operating voltage is started, the microprocessor 21 first sets the flag F to "0" (step S1), and then reads the basic bypass amount G stored in the standby RAM 35 (step S1).
S2), if the standby RAM 35 is normal (step S2-1), this learning value G is set as the initial control amount A.
(Step S3). Whether or not the standby RAM 35 is normal is determined by whether or not the standby RAM 35 stores a certain pattern (value). If the pattern is different, standby RAM
35 is malfunctioning or in its initial state,
The predetermined basic bypass amount α ₀ is set as the learned value G
(Step S2-2).

Next, the microprocessor 21 determines whether the engine 29 is in an idle state based on the state of the idle switch 33 (step S4),
If the judgment result is YES, the lower limit value G1 that the learning value G can take in one learning control period is
G-g1 and upper limit value G2=G+g2 are determined (steps S5 and 6). FIG. 4 is a diagram showing the relationship between the learned value G, the lower limit value G1, and the upper limit value G2, where g1 and g2 are values of about 2% of the learned value G. Next, ROM2
The target rotational speed NE ₀ stored in advance in the engine 29 is compared with the engine rotational speed NE of the engine 29 determined based on the detection result of the rotational speed sensor 34 (step S7). Then, the comparison result is engine speed NE
＞Target rotation speed NE If ₀ , the control amount A is shown in the following formula (1), and engine rotation speed NE < target rotation speed.
If NE is ₀ , the control amount A is expressed by the following equation (2) (steps S8 and 9).

A=A-B(ΔNE)...(1) A=A+B(ΔNE)...(2) Here, B(ΔNE) is determined by the difference ΔNE between the engine rotation speed NE and the target rotation speed NE ₀ . This is the amount of correction.

Next, the microprocessor 21 executes the step
It is determined whether the control amount A obtained in S8 and S9 satisfies the relationship A>G+x (step S10),
If the determination result is YES, G+x is set as the controlled variable A (step S12), and if the determined result is NO, it is determined whether the controlled variable A satisfies the relationship A<G-y (step S11). If the judgment result in step S11 is YES, G-y is set as the control amount A (step S13), and if the judgment result is NO, the process moves to step S14. That is, in steps S10 to S13, in order to prevent excessive control, processing is performed to bring the control amount A within the range shown by the following equation (3).

G−y<A<G+x (3) Next, the microprocessor 21 determines whether learning conditions such as the cooling water temperature being at a predetermined temperature are satisfied (step S14), and if the determination result is NO The process moves to step S22, and if the determination result is YES, the engine speed NE and target speed NE ₀ are compared (step S15). Then, if the comparison result is engine speed NE > target speed NE ₀ ,
The value obtained by subtracting the predetermined amount z from the learned value G is set as the new learned value G (step S16), and if engine speed NE < target speed NE ₀ , the value obtained by adding the predetermined amount z to the learned value G is set as the new learned value G. The learning value is set to G (step S17).

Next, the microprocessor 21 executes the step
S16, 17 Determine whether the obtained new learning value G satisfies the relationship G<G1 (step S18),
If the judgment result is YES, G1 is set as the new learned value G (step S20), and if the judgment result is NO, it is judged whether the new learned value G satisfies the relationship G>G2 (step S19). ). If the determination result in step S19 is YES, G2 is set as a new learned value G (step S21), and if the determination result is NO, the process moves to step S22. That is, step
In S18 to S21, processing is performed to bring the learning value G within the range shown in the following equation (4).

G1<G<G2...(4) Next, the microprocessor 21 executes the step
Control amount A obtained in S8, 9 or steps S12, 13
is outputted via the input/output unit 24 (step S22),
This controls the control valve 32,
The amount of air flowing through the bypass passage 31 corresponds to the control amount A. Next, the microprocessor 21 determines whether the engine is in a stable idle state (step S23). In addition, the judgment as to whether the engine is in a stable idle state is based on conditions such as small fluctuations in engine speed, small difference between engine speed and target speed, and engine condition being stable for a certain period of time. This is done based on whether or not the following holds true.

If the judgment result in step S23 is YES, the microprocessor 21 sets the flag F to "1".
(step S24), and if the judgment result is NO, the value of flag F is held as is (step S25).
After this, the process returns to step S6. Then, if it is determined in step S6 that it is in the idle state,
Perform step S7 in the same manner as described above,
If it is determined that it is not in an idle state, that is, if it is determined that one learning control period has ended, the process of step S26 is performed.

In step S26, a predetermined amount g2 is added to the learning value G obtained at the end of the previous learning control period, and the addition result is
A process is performed in which G2=G+g2 is set as the upper limit of the learning value in the current learning control period. Next, the microprocessor 21 determines whether the flag F is "1" (step S27), and if the determination result is NO, the learning value G obtained at the end of the previous learning control period is
Subtract a predetermined amount g1 from , and this subtraction result G1=G−
Let g1 be the lower limit of the learned value for the current learning control period (step S28), and if the judgment result is YES, a predetermined amount from the learned value G obtained at the end of the previous learning control period.
Subtract g3, and use the subtraction result G1 = G - g3 as the lower limit of the learning value for the current learning control period (step
S29), after which the process returns to step S6. Note that g1 and g3 have a relationship of g1>g3 as shown in FIG. 5, and g3 is set to a value of about 1/4 of g1, for example. Furthermore, since it can be determined that learning has already been completed, g3 may be set to 0 to prohibit further learning.

That is, in this embodiment, as shown in FIG. 5, before the engine reaches a stable idle state even once (before flag F becomes "1"), the learned value in one learning control period is The lower limit permissible variation range of G is set as g1 (step S27), and after the engine reaches a stable idle state at least once (after flag F becomes "1"), during one learning control period. Let the lower limit variation allowable range of the learned value G be g3 (g3<g1), and the learned value G3
Therefore, once the engine reaches a stable idle state, the learning value decreases less than before, and therefore, according to this embodiment, compared to the conventional example, engine stall occurs. It can be made difficult.

In addition, in the embodiment described above, the bypass passage 3
The amount of air supplied to the engine 29 during idling is controlled by controlling the amount of air flowing through the throttle valve 1, but the amount of air supplied to the engine 29 during idling is controlled by controlling the opening degree of the throttle valve 27 with a step motor or the like. Of course, it is also possible to control the amount of air.

〔Effect of the invention〕

As explained above, in the present invention, before the engine reaches a stable idle state, the lower limit variation allowed range of the learned value G in one learning control period is set to the first allowed range (in the embodiment). g1), and once the engine reaches a stable idle state, the lower limit permissible range of the learning value is set to a second permissible range (g3 in the embodiment) which is smaller than the first permissible range. ,
This has the advantage of being able to prevent engine stalling due to foot rest without impairing the learning control function.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, FIG. 3 is a flowchart showing the processing contents of the microprocessor 21, and FIG.
Figure 5 is a diagram showing the upper and lower limits of the learning value,
FIGS. 6 and 7 are diagrams for explaining the problems of the conventional example. 1 is a correction amount calculation means, 2 is a learning control means, 3 is a control amount calculation means, 4 is a control means, 5 is a setting means,
6 is a detection means, 21 is a microprocessor, 22
is ROM, 23 is RAM, 24 is input/output section, 25
is an air cleaner, 26 is a pipe, 27 is a throttle valve, 28 is a surge tank, 29 is an engine, 30
31 is a muffler, 31 is a bypass passage, 32 is a control valve, 33 is an idle switch, 34 is a rotation speed sensor, 35 is a standby RAM, 36 is an ignition switch, 37 and 38 are constant voltage circuits, and 39 is a battery.

Claims (1)

[Scope of Claims] 1. Correction amount calculation means for calculating a correction amount corresponding to the difference between the engine rotation speed and the target rotation; Learning control means for changing the learning value so that the learning value matches the control amount; control amount calculation means for calculating a control amount based on the learning value calculated by the learning control means and the correction amount calculated by the correction amount calculation means; a control means for setting an amount corresponding to the control amount calculated by the calculation means; a setting means for setting a lower limit permissible range of variation of a learned value in one learning control period; and detecting means for detecting, and before the detecting means detects that the engine has reached the stable idle state, the lower limit fluctuation permissible width set by the setting means is set as a first permissible width, and the detecting means After detecting that the engine has reached a stable idle state, the lower limit fluctuation permission range set by the setting means is set to a second permission range smaller than the first permission width.
An idle rotation speed control device equipped with a learning control function characterized in that a permissible range of .