JP2526909B2 - Idle speed control method for internal combustion engine - Google Patents

Description

The present invention relates to an idle speed control method for an internal combustion engine.

(Prior Art and Its Problems) The opening degree of the bypass valve provided in the bypass passage that bypasses the throttle valve during the idle operation of the internal combustion engine, or the opening degree of the throttle valve itself is used as the engine speed detection value and the target idle value. Feedback control is performed according to the deviation from the rotational speed to increase or decrease the intake air amount during idle operation,
A control method for stabilizing idle rotation is known.

Further, as another method for stabilizing the idle rotation, a method of controlling the ignition timing is also known. Idle speed control based on this ignition timing control retards the ignition timing when the detected engine speed is higher than the target idle speed and retards the ignition timing when the detected engine speed is lower than the target idle speed, depending on the deviation between the detected engine speed and the target idle speed. By advancing the timing, the engine speed is controlled near the target idle speed.

These conventional idle speed control methods generally
Emphasizing the stability of idle speed, that is, preventing hunting, as shown in FIG. 6, a dead zone having a predetermined upper and lower rotation speed range with respect to the target idle speed (in FIG. (The dead band of the rotation speed range of α is provided), and when the engine speed falls within this dead zone, the control operation is interrupted and the increase or decrease of the intake air amount or the increase or decrease of the advance amount of the ignition timing is stopped. I am trying.

Further, in order to improve the control stability, it is preferable to control the engine speed slowly as the engine speed approaches the target idle speed, that is, to set the control gain small.

According to such a conventional control method, as shown in FIG. 6, when the engine speed falls toward the target idle speed and enters the dead zone, the control is interrupted at the time when the dead zone is entered. Therefore, the engine speed may settle near the upper limit of the dead zone. When the engine speed increases toward the target idle speed and enters the dead zone, the engine speed may settle near the lower limit of the dead zone. In this way, the statically determined rotation speed may be offset from the target idle rotation speed by the maximum rotation speed of the dead zone width α with respect to the target idle rotation speed.

The present invention has been made to solve such a problem, and an internal combustion engine which is designed to settle the idle speed as close to the target idle speed as possible without impairing the stability of the idle speed. An object is to provide an idle speed control method.

(Means for Solving the Problems) According to the present invention in order to achieve the above-mentioned object, according to the present invention, the internal combustion engine is operated according to a deviation between an engine speed detection value and a target idle speed during idle operation of the internal combustion engine. The control amount for controlling the operation of the engine is adjusted so as to reduce the deviation, and the upper limit rotation speed at which the engine rotation speed detection value is higher than the target idle rotation speed by a predetermined value and the lower limit lower than the target idle speed by a predetermined value. In the idle speed control method of controlling the engine speed to be in the vicinity of the target idle speed without changing the control amount when the engine speed is between the engine speed detection value, the upper limit speed and the lower limit. A procedure of comparing the engine speed with the target idle speed after the engine speed detection value is larger than the upper limit engine speed. By comparison, until the engine speed detection value becomes smaller than the target idle speed, the control amount is adjusted in a direction to reduce the deviation according to the deviation between the engine speed detection value and the target idle speed. When the engine speed detection value is smaller than the lower limit engine speed, the engine speed detection value is then compared with the target idle speed, and the engine speed detection value becomes larger than the target idle speed. There is provided an idle speed control method for an internal combustion engine, comprising a procedure of adjusting the control amount in a direction to reduce the deviation according to a deviation between a detected rotation speed value and the target idle speed.

(Operation) When the engine speed changes from the outside of the dead band set between the predetermined upper and lower limit speeds toward the target idle speed, the dead band is removed once, and therefore the engine speed always reaches the target idle speed. Can be reached and the engine speed can be settled near the target idle speed.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows an idle speed control device for an internal combustion engine which implements the method of the present invention. In the figure, reference numeral 10 indicates, for example, a 4-cylinder gasoline engine, and this engine 10 has an intake pipe.
12 are connected. An air cleaner 13 is attached to an air opening end of the intake pipe 12, and a Karman vortex type air flow sensor 14 for detecting a flow rate A of air sucked into the engine 10 is arranged. Electronic control unit (ECU) 20 described later in
And supplies an air flow rate detection signal to the electronic control unit 20.

A throttle valve 15 interlocked with an accelerator pedal (not shown) is arranged in the intake pipe 12, a bypass passage 17 bypassing the throttle valve 15 is connected to the intake pipe 12, and one end of the bypass passage 17 is upstream of the throttle valve 15. In addition, in the intake pipe 12 downstream of the air flow sensor 14, the other end is a throttle valve.
15 It communicates with each of the intake pipes 12 downstream. Bypass passage 17
An idle speed control valve (idle control valve) 18 is arranged in the middle. The idle control valve 18 is composed of a valve body 18a that opens and closes the bypass passage 17, and a pulse motor 18b that is connected to the valve body 18a and controls the valve opening. The pulse motor 18b is the electronic control unit 2
It is electrically connected to the output side of 0 and controls the valve opening degree of the valve body 18a according to the number of drive pulse signals supplied from the electronic control unit 20. Then, by opening the idle control valve 18, the air that passes through the bypass passage 17 and bypasses the throttle valve 15 is supplied to the engine 10.
A DC motor may be used instead of the pulse motor as the driving means for opening and closing the idle control valve 18.

A spark plug 26 is attached to each cylinder 10a of the engine 10, and the spark plug 26 is connected to an output side of the electronic control unit 20 via a distributor 24 and an igniter device 22. The igniter device 22 is for generating a secondary high voltage by an ignition coil (not shown) based on an ignition control signal from the electronic control unit 20.
This high voltage is sequentially supplied to the spark plug 26 of each cylinder by the distributor 24 in a predetermined order to ignite the air-fuel mixture in the cylinder 10a.

Various sensors are provided on the input side of the electronic control unit 20, for example, an idle switch 30 for detecting the fully closed position of the throttle valve 15, an engine speed sensor 31 attached to a camshaft (not shown) for detecting the engine speed Ne. , A cooling water temperature sensor 32 for detecting the engine cooling water temperature Tw, an air conditioner switch 33 for detecting the on / off state of an air conditioner (air conditioner) (not shown), and other sensors 34 such as vehicle speed and atmospheric pressure are connected, respectively. Supplies a detection signal to the electronic control unit 20.

The electronic control unit 20 includes a central processing unit (CPU) (not shown), a storage device such as RAM and ROM, an I / O interface, etc., and the electronic control unit 20 is an idle described later according to a control program stored in the storage device. Executes rotation speed control, etc.

Next, the operation of the control device configured as described above will be described first.
This will be described with reference to the drawings and FIGS. 3 to 5.

3 to 5 are flowcharts showing a control procedure of an idle speed control routine executed by the electronic control unit 20, in which the throttle valve 15 is fully closed by the idle switch 30, and This is executed by the engine speed sensor 31 when the engine speed Ne is equal to or lower than a predetermined speed.

First, the electronic control unit 20 determines in step 40 shown in FIG. 3 whether or not a stop (STOP) mode, which will be described later, was set during the previous execution. When the above condition is satisfied and step 40 of the routine is executed for the first time, as described below, the mode other than the STOP mode is set as the initial value of the control mode. Is negative (No), and the routine proceeds to step 50 shown in FIG.

In step 50, it is determined whether or not the control mode is set to the closed mode. When the throttle valve 15 is fully closed to decelerate from the high-speed operation range and the program is executed for the first time, the closed mode is stored in the storage device of the electronic control unit 20 as an initial value, and the engine is started when the engine is started. When the rotation speed rises and rises toward the target idle rotation speed N _ID , the open mode is stored as an initial value. Here, the closed mode is a control mode in which the idle control valve 18 is controlled to the closed side by a predetermined method to reduce the engine speed Ne, and the open mode, on the contrary, controls the idle control valve 18 by a predetermined method. This is a control mode when the engine speed Ne is increased by controlling the opening side. The STOP mode is a control mode in which the engine speed Ne is within the dead zone set as described later, and the idle control valve 18 is not operated on the open side or the close side. When the engine speed Ne decelerates from the high-speed operation region toward the target idle speed N _ID (when the engine speed is in the state before the time t1 shown in FIG. 1), it is closed as the initial value as described above. Since the mode is set, the determination result of step 50 is affirmative (Ye
s), and proceed to step 51.

The above-described target idle speed N _ID is set according to the load state of the engine 10 when the engine 10 is idle, for example, by the cooling water temperature detected by the cooling water temperature sensor 32, the on / off state of the air conditioner switch, and the like.

In step 51, it is judged whether or not the engine speed Ne is less than or equal to the target idle speed N _ID and is greater than a predetermined lower limit speed (N _ID -α) (a dead band indicated by a diagonal line before the time t2 in FIG. 1). Determine if it is in the area). Since the engine speed Ne is in the deceleration state before the time t1 in FIG. 1, this determination is negative and the electronic control unit
20 proceeds to step 56 of FIG. 5, the engine speed Ne is determined whether or not the target idle speed N _ID is greater than, in the closed mode when the engine speed Ne is larger than the target idle speed N _ID If it is smaller (step 58), the mode is set to the open mode (step 59), and the process proceeds to step 48 in FIG.

At step 48, the set mode and the deviation ΔN (= Ne−N) between the engine speed Ne and the target idle speed N _ID are set.
_ID ), that is, the valve opening of the idle control valve 18 is calculated and set. This control amount setting method is a known method, and the engine speed Ne is equal to the target idle speed N _ID.
The control amount is calculated so that the control gain becomes smaller as the value approaches, that is, the control is performed slowly. The electronic control unit 20 outputs a drive signal to the pulse motor 18b corresponding to the valve opening of the idle control valve 18 calculated in this way, and reduces the bypass air amount.

The electronic control unit 20 uses steps 30, 50, 51,
By repeating steps 48 and 48, the engine speed Ne decreases due to a decrease in the bypass air, but the engine speed Ne reaches the predetermined upper limit speed (N _ID +
Even if it crosses α) and falls below this, the STOP mode is not set and the closed mode continues. Then, when the engine speed Ne falls across the target idle speed N _ID (at time t2 in FIG. 1) and the determination result of step 51 becomes affirmative, that is, the engine speed Ne becomes the target idle speed N. _{When the} condition of being equal to or less than _{ID and} greater than the predetermined lower limit rotation speed (N _ID -α) is satisfied, the process proceeds to step 54, the STOP mode is set, and the execution of the program this time is ended. When the STOP mode is set, the control of the idle control valve 18 is interrupted, and the valve opening degree of the idle control valve 18 is the previous value,
That is, the value immediately before the interruption of the control is held, and the amount of bypass air supplied to the engine 10 via the bypass passage 17 does not increase or decrease.

Thus, the engine speed Ne is equal to the target idle speed N
_The engine speed Ne is set to the target idle speed N _ID because the STOP mode is set for the first time when it descends across the _ID.
It will settle in the vicinity.

When the STOP mode is set, the determination result of step 40 becomes positive, and the electronic control unit 20 proceeds to step
42, the engine speed Ne is the target idle speed N _ID
If the engine speed Ne is higher than the target idle speed N _ID, it is set to the closed mode (step 43). If the engine speed Ne is lower than the target idle speed N _ID , the open mode is set (step 44). Proceed to 46.

Then, in step 46, the absolute value of the deviation ΔN between the engine speed Ne and the target idle speed N _ID (= | Ne−N
_ID |) is greater than a predetermined value α, that is, whether the engine speed Ne is out of the dead zone.
If the engine speed Ne is within the dead zone, the result of the determination in step 46 is negative, the process proceeds to step 49, and the step 43
Alternatively, instead of the mode once set in 44, the mode is set again to the STOP mode, and the execution of the program this time is ended. As long as the engine speed Ne is within the dead zone (from t2 in Fig. 1)
During time t4), step 49 is repeatedly executed, and the idle control valve 18 is continuously maintained at the previously set valve opening degree.

While the engine speed Ne is within the dead zone, for example, if the headlamp is turned on and the electric load increases (see FIG. 1).
At time t3), the engine speed Ne starts to decrease. While the engine speed Ne is in the dead zone (from time t3 to time t4 in FIG. 1), the STOP mode continues to be executed, but the engine speed Ne is lower than the predetermined lower limit speed (N _ID −α). When it is out of the dead zone (after time t4 in FIG. 1), the determination result of step 46 becomes affirmative, the process proceeds to step 48, the control amount according to the mode and the deviation ΔN is calculated, and the idle control valve 18 is bypassed. The valve is opened to increase the amount of air and increase the engine speed Ne. At this time, the determination result of step 42 is negative,
Open mode is set at 44.

When the open mode is set, the determination results of Steps 40 and 50 are both negative, the electronic control unit 20 proceeds to Step 52, and the engine speed Ne is equal to or higher than the target idle speed N _ID and the predetermined value is obtained. Upper speed limit (N _ID +
It is determined whether it is smaller than (α) (from t4 in FIG. 1)
It is determined whether it is in the shaded area between t5 points).
When the engine speed Ne is lower than the target idle speed N _ID , the determination result of step 52 becomes negative, the electronic control unit 20 proceeds to step 56, and the engine speed Ne is higher than the target idle speed N _ID. After determining whether or not the open mode is set in step 59, the third mode is set.
Proceed to step 48 of the figure. And the engine speed Ne
The open mode continues to be executed until the temperature rises across the target idle speed N _ID (t5 in FIG. 1).

The engine speed Ne rises across the target idle speed N _ID and increases in the above range (predetermined upper limit speed (N _ID + α)).
When it enters a smaller range (larger than the target idle speed N _ID ), the determination result of step 52 becomes affirmative, and the STOP mode is set in step 54 to terminate the execution of the program this time. Then, as long as the engine speed Ne is within the dead zone (between time t5 and time t7 in FIG. 1), the STOP mode is continuously executed according to the same procedure as described above, and the valve opening degree of the idle control valve 18 is set to the previous value (second time). It is held at the value set immediately before time t5 in Fig. 1).

Next, if the engine load such as electric load is suddenly reduced while the engine speed Ne is within the dead zone, the engine speed
Ne starts to rise (after time t6 in Fig. 1). While the engine speed Ne is in the dead zone (between t6 and 7 in FIG. 1), the STOP mode is continuously executed, but the engine speed Ne exceeds the predetermined upper limit speed (N _ID + α). When it comes out of the dead zone (after time t7 in FIG. 1), the determination result of the step 46 becomes affirmative, the step 48 is executed, and the control amount according to the mode and the deviation ΔN is calculated. At this time, the idle control valve 18 is closed so as to reduce the bypass air amount and lower the engine speed Ne. At this time, the determination result of step 42 is affirmative, and the closed mode is set in step 43.

Hereinafter, as described above, until the engine speed Ne falls across the target idle speed N _ID (see FIG. 1).
Closed mode control is executed until t8) and then ST
OP mode is executed. Thus, the engine speed Ne can be settled near the target idle speed N _ID ,
As in the conventional control method, the inconvenience of causing the target idle speed N _ID and the offset by being settled near the upper limit rotation speed and the lower limit rotation speed of the dead zone is solved.

In the above embodiment, the idle control valve 18 arranged in the bypass passage 17 is adjusted to increase or decrease the intake air amount to control the idle speed, but the present invention is not limited to this, and the intake pipe is not limited to this. It is also possible to increase or decrease the intake air amount by forcibly opening and closing the valve opening of the throttle valve 15 which is arranged in the middle of 12 and which operates in conjunction with the accelerator pedal.

In the method of the present invention, the amount of intake air is adjusted to control the idle speed, but the ignition timing control signal supplied to the igniter device 22 is used to adjust the ignition timing advance amount to control the idle speed. You may make it apply to a well-known method.

(Effects of the Invention) As described in detail above, according to the idle speed control method for an internal combustion engine of the present invention, when the engine speed detection value is higher than the upper limit rotation speed, the engine speed detection value is thereafter set to the target idle speed. The engine speed is controlled until it becomes smaller, and when the engine speed detection value is smaller than the lower limit engine speed, the engine speed is controlled until the engine speed detection value becomes larger than the target idle speed. The inconvenience that the engine speed is settled in the vicinity of the upper and lower limit rotation speeds of the dead zone as in the rotation speed control method, and an offset occurs between the statically fixed rotation speed and the target idle rotation speed to be originally settled, is eliminated. It has an excellent effect that the engine speed at the time of idling can be accurately controlled to be close to the target idling speed.

[Brief description of drawings]

FIG. 1 is a timing chart showing the time change of the engine speed for explaining the method of the present invention, FIG. 2 is a block diagram showing the overall configuration of an idle speed control device for carrying out the method of the present invention, and FIGS. FIG. 5 is a flowchart showing an idle speed control procedure executed by the electronic control unit (ECU) 20 shown in FIG. 2, and FIG. 6 is a time change of the engine speed for explaining a conventional control method. 2 is a timing chart showing 10 ... Internal combustion engine, 12 ... Intake passage, 15 ... Throttle valve, 17 ... Bypass passage, 18 ... Idle control valve (bypass valve), 20 ... Electronic control unit, 22 ... Igniter device, 24 ... … Distributor, 26 …… Spark plug, 30 …… Idle switch, 31 …… Engine speed sensor.

Claims (3)

(57) [Claims] 1. During idle operation of an internal combustion engine, according to a deviation between an engine speed detection value and a target idle speed,
The control amount for controlling the operation of the internal combustion engine is adjusted to reduce the deviation, and the engine speed detection value is a predetermined value larger than the target idle speed by a predetermined value and a predetermined value from the target idle speed. When it is between the lower limit engine speed and a small lower limit engine speed, in an idle engine speed control method for controlling the engine engine speed in the vicinity of the target idle engine speed without changing the control amount, an engine engine speed detection value and the upper engine speed limit and When the engine speed detection value is larger than the upper limit speed, the engine speed detection value is compared with the target idle speed, and the engine speed detection value is the target value. Until the engine speed becomes lower than the idle speed, the control amount is reduced to a small value in accordance with the difference between the engine speed detection value and the target idle speed. Direction, and when the engine speed detection value is smaller than the lower limit speed, the engine speed detection value is then compared with the target idle speed, and the engine speed detection value is lower than the target idle speed. Until the engine speed increases, the idle speed control of the internal combustion engine is performed according to the deviation between the detected engine speed and the target idle speed. Method. 2. The idle speed control method for an internal combustion engine according to claim 1, wherein the control amount is an intake air amount. 3. The idle speed control method for an internal combustion engine according to claim 1, wherein the control amount is an ignition timing advance amount.