JP2002106387A - Idle rotation speed control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the rotation speed suited to the warming-up state of an engine in a case of restarting it after suspending the feedback control of the idle rotation speed. SOLUTION: A central processing unit (CPU 31) in an electronic control unit(ECU) 30 calculates a base air quantity according to the warming-up state of the engine, calculates an air F/B quantity based on a deviation between a target rotation speed and an actual rotation speed, when feedback control conditions of the idle rotation speed are satisfied, and controls an intake air quantity to the engine according the base air quantity and the air F/B quantity so that the rotation speed in the idle state becomes the target value. The CPU 31 calculates the ratio between the air F/B and the base air quantity and, when the feedback control conditions are changed from the satisfied conditions to the unsatisfied conditions, CPU uses the ratio between the air F/B and the base air quantity calculated right before sets the air F/B quantity according to the ratio after this in the unsatisfied state of the conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device for controlling an amount of intake air to an engine such that the engine speed in an idle state becomes a target value.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open Publication No.
Japanese Patent Application Laid-Open No. 195430 discloses an "engine idle speed control device". In the device disclosed therein, when an engine shifts from an idle state to a non-idle state, control of an idle speed control valve (ISC valve) is performed. The amount was time-decayed. Thus, when shifting to the non-idle state, a so-called breathing phenomenon caused by a sudden decrease in the amount of intake air is eliminated.

However, in the device disclosed in the above publication, the control amount of the ISC valve is attenuated at a predetermined rate with respect to a unit time, so that the degree of attenuation of the control amount does not match the actual warm-up state of the engine. It is conceivable that the controllability of the rotational speed is deteriorated. That is, when the engine is started, the degree of water temperature rise during non-idle time varies depending on the water temperature at that time. Therefore, when returning to the idle state in a short time after shifting to non-idle, the control amount during idle return will be the engine warm-up. Incompatible with the condition, the intake air amount is reduced too much or the reduction amount is insufficient. Further, adaptation is required to determine a constant for time decay, which causes problems such as an increase in the number of design steps.

[0004] In addition, Japanese Patent Publication No. Hei 2-26691 discloses a "throttle valve opening control device". In the device disclosed in Japanese Patent Publication No. 2-26691, when the engine is not idling, the temperature of the engine is set to a predetermined value according to the engine state. , The opening degree of the throttle valve is controlled to decrease. Thus, when returning from the running state to the idle state after the engine is started at a low temperature, an appropriate amount of air is supplied. Actually, the ratio of the output of the return pulse (control amount to the throttle valve closing side) to the temperature rise is determined according to the engine water temperature when the accelerator is depressed from the idle state.

However, the apparatus described in Japanese Patent Publication No. 2-26691 still has the following problems. That is,
In the device of the above publication, the water temperature threshold value for controlling the throttle valve to the closed side is determined immediately before the accelerator is depressed, and the water temperature threshold value is set lower as the engine water temperature is lower (interval of the output of the return pulse). Is narrowed). for that reason,
If the engine becomes non-idle immediately after starting at extremely low temperatures, and the non-idle state continues and the engine gradually warms up, if the warm-up has progressed to some extent, the water temperature threshold value will change to the actual warm-up state. Will not fit. Therefore, when the engine returns from the non-idle state to the idle state, the opening degree of the throttle valve does not match the warm-up state of the engine, and the controllability of the rotational speed deteriorates. Also in this case, fine adaptation is required, and the number of design steps increases.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problem, and an object thereof is to provide feedback control of an idle speed such as when returning from non-idle to idle. An object of the present invention is to provide an engine idle speed control device capable of performing a suitable speed control suitable for a warm-up state of the engine when the engine is restarted after being interrupted.

[0007]

In the idle speed control device of the present invention, it is assumed that a base air amount is calculated according to a warm-up state of an engine, and a target value is set when a feedback control condition of the idle speed is satisfied. The air F / B amount is calculated based on the deviation between the rotation speed and the actual rotation speed. Then, the intake air amount to the engine is controlled in accordance with the base air amount and the air F / B amount so that the rotation speed in the idle state becomes the target value.

According to the first aspect of the present invention, the air F
The ratio between the / B amount and the base air amount is calculated (air amount ratio calculating means). When the feedback control condition shifts from satisfied to unsatisfied, the ratio between the air F / B amount calculated immediately before and the base air amount is used. Thereafter, when the condition is not satisfied, the air is adjusted according to the ratio. The F / B amount is set (air F / B amount setting means).

In short, the base air amount changes according to the warm-up state of the engine, and decreases as the warm-up proceeds. In this case, the balance between the air F / B amount and the base air amount is obtained by using the ratio of the air F / B amount and the base air amount as described above and setting the air F / B amount according to the ratio. The air F / B amount is set while always being maintained. Therefore, after the feedback control condition is not satisfied, the air F / B amount changes according to the change in the base air amount, that is, the degree of warm-up of the engine. Therefore, when the feedback control condition is satisfied again and the idle speed control is restarted, the air F / B amount corresponds to the warm-up state at that time, and the rotation speed reaches the target value immediately after the return of the feedback control. It converges on the rotation speed. That is,
It is possible to perform suitable rotation speed control suitable for the warm-up state of the engine. Further, unlike the above-described apparatus of the related art, no adaptation is required, so that the number of design steps can be reduced.

[0010] Specifically, as described in claim 2,
When the base air amount is a and the air F / B amount when the feedback control condition is satisfied is b, the air F / B
The B amount setting means uses a ratio “b / a” between the air F / B amount and the base air amount immediately before the feedback control condition shifts from being satisfied to not being satisfied, and using the ratio and the latest value QBASE of the base air amount. The air F / B amount may be set according to the product, QBASE × (b / a). In this case, when the feedback control condition is not satisfied, the air F / B amount required for the base air amount at each time can be easily calculated.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The device according to the present embodiment embodies an idle speed control device for suitably controlling the idle speed of an on-vehicle multi-cylinder engine, and controls the engine to converge the idle speed to a target value. Adjust the intake air volume. Hereinafter, an engine control device for realizing idle speed control will be described in detail.

FIG. 1 is a configuration diagram showing an outline of an engine control device according to the present embodiment. In FIG. 1, an intake pipe 2 and an exhaust pipe 3 are connected to an engine 1. A throttle valve 4 is provided in the intake pipe 2, and the opening of the throttle valve 4 is controlled by driving a throttle actuator 5. The throttle valve 4 is provided with a throttle opening sensor 6 and a surge tank 7 of the intake pipe 2.
Is provided with an intake pressure sensor 8.

A piston 10 is disposed in the cylinder 9, and a combustion chamber 13 above the piston 10 communicates with the intake pipe 2 and the exhaust pipe 3 via an intake valve 14 and an exhaust valve 15. The cylinder 9 (water jacket) is provided with a water temperature sensor 21 for detecting a cooling water temperature. An intake port 17 of the engine 1 is provided with an electromagnetically driven injector 18 for each cylinder, and the injector 18 injects fuel (gasoline) supplied from a fuel tank (not shown). The cylinder head 12 is provided with an ignition plug 19. The rotation of a crankshaft (not shown) accompanying the combustion is detected by a rotation speed sensor 20.

The ECU 30 includes a CPU 31, a ROM 32,
The microcomputer is mainly configured by a RAM 33, a backup RAM 34, and the like. The ECU 30 includes:
Each detection signal is input from the above-described throttle opening sensor 6, intake pressure sensor 8, rotation speed sensor 20, water temperature sensor 21, etc., and the ECU 30 determines the throttle opening, intake pressure, engine speed, Detects engine water temperature.

The CPU 31 performs various calculations in accordance with the program in the ROM 32, calculates the optimal fuel injection amount, ignition timing, and intake air amount based on the engine operating condition at each time, and uses a control signal corresponding to the calculation result. The driving of the injector 18, the spark plug 19, and the throttle actuator 5 is controlled. In particular, the CPU 31 drives the throttle actuator 5 to adjust the opening of the throttle valve 4 so that the engine speed in the idle state becomes the target value, and controls the amount of air taken into the engine 1.

Next, the idle speed control will be described in detail. FIG. 2 is a flowchart showing a procedure for calculating an air control amount for controlling the idling speed. This process is performed, for example, for each fuel injection of each cylinder (180 ° for a four-cylinder engine).
This is performed by the CPU 31 at every CA) or at a predetermined time interval.

In FIG. 2, first, in step 101,
The base air amount QBASE is calculated according to the water temperature Tw at that time. At this time, as the engine water temperature Tw is lower, a larger value is set as the base air amount QBASE. In the following step 102, it is determined whether or not the F / B condition for the idle speed is satisfied. When the F / B condition is determined, it is mainly determined whether or not the engine is in an idle state. However, besides, the ignition timing F
/ B control is performed or not, and the ignition timing F
If the / B control is being performed, a negative determination may be made in step 102.

If the F / B condition for the idle speed is satisfied, the routine proceeds to step 103, where the air F / B amount QI is calculated based on the difference between the engine speed Ne and the target speed Nt. In the following step 104, the base air amount QBAS
A ratio KQI of the air F / B amount QI to E is calculated (KQI = QI / QBASE). When the base air amount QBASE and the air F / B amount QI are calculated as described above, the throttle actuator 5 is driven based on the QBASE and QI. Then, the intake air amount is adjusted accordingly, and as a result, the idle speed is controlled to the target value.

On the other hand, when the F / B condition of the idle speed is not satisfied and the open control is performed,
05, and using the ratio KQI calculated before in step 104, the open air F / B amount QIOP
Calculate N. That is, the ratio KQI is multiplied by the base air amount QBASE calculated this time, and the product is defined as the open air F / B amount QIOPN (QIOPN = K
QI / QBASE).

Thereafter, at step 106, it is determined whether or not QI> 0 and QIOPN <QI. At step 107, QI <0 and QIOPN>
It is determined whether it is QI. Steps 106 and 1 above
07 is for judging whether or not the air F / B amount QIOPN is changing in the direction of reducing the control amount. If any of steps 106 and 107 is YES, step 10 is executed.
In step 8, the air F / B amount QI is updated by QIOPN (QI = QIOPN). In short, irrespective of whether the QI is positive or negative, QI updating is permitted only when the absolute value of QIOPN decreases. In the present embodiment, step 104 corresponds to “air amount ratio calculating means” of the present invention, and steps 105 and 108 correspond to “air F / F”.
B amount setting means ".

Next, referring to the time chart of FIG.
An outline of idle speed control will be described. FIG. 3 shows the behavior of the engine speed Ne and the transition of various control amounts when the engine is started.

The engine speed Ne rapidly rises with the start of the engine, and after falling to the peak speed, starts decreasing.
At time t1, the engine speed once falls below the target idle speed at start (target speed Nt). The target rotation speed Nt is an idle rotation speed set in accordance with the engine water temperature and the like. For example, when the engine is started at a low temperature, Nt is set to 1200 rpm. The base air amount QBASE is set at any time according to the engine warm-up state (water temperature Tw).

At time t1, the engine speed Ne is changed.
To converge to the target rotational speed Nt.
B control is started. That is, the control amount corresponding to the difference between the engine speed Ne and the target speed Nt is sequentially integrated to calculate the air F / B amount QI. And air F / B
The air control amount required for idle speed control is calculated based on the amount QI and the base air amount QBASE, and the throttle actuator 5 is driven accordingly.

Thereafter, at time t2, for example, the accelerator pedal is depressed, and the engine speed Ne increases. At this time, since the state shifts from the idle state to the non-idle state, the F / B condition of the idle speed is not satisfied, and the open control is started. After time t2, air F immediately before t2
The open air F / B amount QI (QIOPN) is calculated according to the ratio between the / B amount QI and the base air amount QBASE ("QI1 / QBASE1" in the figure). in this case,
The air F / B amount QI is set while the balance with respect to the base air amount QBASE is always maintained. In other words, when the base air amount QBASE changes as shown in the figure due to the warm-up of the engine (change of the water temperature Tw), the air F / B amount QI (QIOPN) gradually changes (attenuates) in accordance with the change.

Thereafter, at time t3, the control returns to the idle state again, and the F / B control of the idle speed is restarted.
At this time, the air F / B amount QI corresponds to the warm-up state at time t3. Therefore, immediately after the return of the F / B control, the engine speed Ne converges to the target speed Nt. Therefore, as shown by the two-dot chain line in the figure,
Immediately after the return from idle, the air F / B amount QI is too large and the engine speed Ne increases (circled number 1 in the figure), or the air F / B amount QI is too small and the engine speed Ne decreases. (Circled number 2 in the figure) does not occur.

According to the embodiment described above, the following effects can be obtained. When the F / B condition for the idle speed becomes unsatisfied, the ratio between the air F / B amount QI immediately before and the base air amount QBASE is used, and during the open control thereafter, the air F / B amount QI according to the ratio is used. Is set, when the F / B control of the idle rotation speed is restarted, the air F / B amount QI becomes suitable for the warm-up state at that time. Therefore, the rotation speed converges to the target rotation speed immediately after the return of the F / B control, and suitable rotation speed control suitable for the warm-up state of the engine can be performed. Further, in the above-described device, adaptation for control amount attenuation is not required, and design man-hours can be reduced.

The present invention can be embodied in the following forms other than the above. In the above embodiment, the base air amount QBASE is calculated according to the water temperature Tw, but this is changed.
For example, a learning value and a target rotation speed change correction term are added to the water temperature correction term based on the water temperature Tw, and the sum thereof is used as the base air amount QBA.
SE and QBASE
It may be added to a parameter for calculation. Also,
Basically, the base air amount QBASE may be calculated according to the warm-up state of the engine, and the base air amount QBASE may be calculated according to the cylinder wall temperature, the intake air temperature or the like instead of the water temperature Tw. .

In the above embodiment, the throttle actuator is used to electronically control the opening of the throttle valve to control the amount of intake air during idling operation. Instead, the throttle valve is provided in the bypass passage of the intake pipe. A so-called ISC valve may be provided to control the intake air amount by adjusting the opening of the throttle valve during idle operation. Also in this case, the above-described excellent effects can be obtained similarly.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of an engine control device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a procedure for calculating an air control amount for controlling an idle speed.

FIG. 3 is a time chart showing an outline of idle speed F / B control;

[Explanation of symbols]

 1. Engine, 30 ECU, 31 CPU.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F02D 45/00 322 F02D 45/00 322F 322C (72) Inventor Satoshi Watanabe 1st Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Car Stock Company F term (reference) 3G065 AA04 CA22 DA04 DA15 EA02 GA01 GA09 GA10 GA41 HA21 HA22 KA02 3G084 BA05 CA02 CA03 DA04 FA10 FA11 FA20 FA33 3G301 HA01 KA05 KA07 LA03 PA07Z PA11Z PE01Z PE08Z

Claims (2)

[Claims] An air F / B amount is calculated based on a deviation between a target rotation speed and an actual rotation speed when a feedback control condition for an idle rotation speed is satisfied. An idle speed control device that calculates and controls the amount of intake air to the engine according to the base air amount and the air F / B amount so that the engine speed in the idle state becomes a target value. Air amount ratio calculating means for calculating the ratio between the air amount and the base air amount; and when the feedback control condition shifts from being satisfied to not being satisfied, the air F / B amount calculated by the air amount ratio calculating means and the base air immediately before that. After that, when this condition is not satisfied, the air F / B
An idle speed control device for an engine, comprising: an air F / B amount setting means for setting an amount. 2. When the base air amount is a and the air F / B amount when the feedback control condition is satisfied is b,
The air F / B amount setting means uses the ratio “b / a” between the air F / B amount and the base air amount immediately before the feedback control condition shifts from being satisfied to not being satisfied, and the latest of the ratio and the base air amount. 2. The engine idle speed control device according to claim 1, wherein the air F / B amount is set by a product of the value QBASE and QBASE × (b / a).