JP3078700B2 - Idle speed control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling an idling speed of an automobile engine.

[0002]

2. Description of the Related Art In a conventional idle speed control method, a target speed during idling is set, for example, as in an engine speed control device disclosed in Japanese Patent Laid-Open No. 50358/1991, and the target speed and the actual speed are set. The control amount is calculated so that the engine speed matches the target speed according to the deviation from the engine speed, and the opening of the air control valve that adjusts the amount of air supplied to the engine is adjusted according to the control amount. What performs feedback control is known. Usually, in such feedback control of the air control valve, the control amount is set so as to increase as the deviation increases, in order to match the target rotational speed as quickly as possible. Therefore, there is no difference between the time required to match the target rotational speed from the state where the target rotational speed is significantly deviated from the target rotational speed and the time required to coincide from the state where the target rotational speed slightly deviates from the target rotational speed. I have.

[0003]

On the other hand, it is known that even when idling, the absolute amount of intake air is large when the engine speed is high. This means that in the case of performing the above-described feedback control, the air amount obtained by controlling the opening degree according to a control amount when the engine speed is low and the air amount obtained when the engine speed is high Even if the air amount by the control amount is the same,
Since the required amount of air is large when the engine speed is high, the ratio of the obtained air amount contributing to the rotation is smaller than when the engine speed is low. That is, irrespective of the level of the engine speed, even if the time required for correction to the target speed is to be made uniform, the rate at which the amount of air controlled by the air control valve contributes to the rotation is different. Sometimes it is not possible to make time.

An object of the present invention is to solve such a problem.

[0005]

In order to achieve the above object, the present invention takes the following measures. That is, in the idle speed control method according to the present invention, the suction passing through the bypass passage is controlled by controlling the opening of the flow control valve provided in the bypass passage bypassing the throttle valve based at least on a change in the engine speed. An idle speed control method for controlling the amount of air and controlling the engine speed during idling to approach the idle target speed, detecting the engine speed,
Calculate the deviation between the detected engine rotational speed and the idle target rotational speed at that time, determine a correction value for the opening of the flow control valve based on the deviation, and adjust the opening corrected by the determined correction value. The flow control valve was opened in response to the
If the engine speed is higher than the set speed,
The engine speed sets the cycle for calculating the correction value of the
By making it shorter than when the rotation speed is lower than the
It is characterized in that the change speed of the correction amount is increased .

[0006]

[Action] as long as such a configuration, the opening of the flow control valve, will be rectified by the correction value based on the deviation between the engine speed and the target idle speed. This correction value is
Engine speed is higher than the set speed
Is the cycle at which the engine speed is set.
Since the calculation is made shorter than when the engine speed is lower than the number, the correction value differs between the case where the engine speed is high and the case where the engine speed is low even if the deviation is the same. That is, when the deviation is the same, the correction value when the engine speed is high can be made larger than when the engine speed is low,
The opening degree of the flow control valve is changed depending on the difference in the engine speed at that time, and the intake air amount contributing to the rotation can be adjusted to the same extent at that time. This makes it possible to equalize the time required to reach the idle target rotation speed.

[0007]

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

The engine schematically shown in FIG. 1 is for an automobile, and its intake system 1 is provided with a throttle valve 2 that opens and closes in response to an accelerator pedal (not shown), and bypasses the throttle valve 2. A bypass passage 3 is provided, and a flow control valve 4 for controlling the idle speed is provided in the bypass passage 3. The flow control valve 4 is of an electronic opening and closing type, which is abbreviated as a large flow rate VSV, and has a calculation duty ratio DIS of a drive voltage applied to a terminal 4a thereof.
By controlling C, its substantial opening can be changed, whereby the air flow rate in the bypass passage 3 can be adjusted. That is, a pair of the bypass passage 3 and the flow control valve 4 unifies a bypass system path normally provided for each correction item, and the duty ratio DISC includes those. The water temperature correction amount DAAV, which is the warm-up correction increase amount, the startup correction amount, the rotation feedback correction amount DFB, the load correction amount DAPP, and the like are determined.

The intake system 1 is further provided with a fuel injection valve 5, and the fuel injection valve 5 and the flow control valve 4 are controlled by an electronic control unit 6.

The electronic control unit 6 includes a central processing unit 7
, A storage device 8, an input interface 9, and an output interface 11. The input interface 9 has an intake pressure signal a output from an intake pressure sensor 13 for detecting the pressure in the surge tank 12 and a rotational speed output from a rotational speed sensor 14 for detecting the engine rotational speed NE. A signal b, a vehicle speed signal c output from a vehicle speed sensor 15 for detecting the vehicle speed, an LL signal d output from an idle switch 16 for detecting the open / closed state of the throttle valve 2, a cooling water temperature of the engine as an engine temperature Temperature sensor 17 for detecting
And the like are output. From the output interface 11, the fuel injection valve 5 is
A drive signal f corresponding to the calculated fuel injection time is supplied to the flow control valve 4 and a calculated duty ratio D, which will be described later.
A control signal g based on the ISC is output. Although not shown, the electronic control unit 6 has an A / D for converting an input analog signal into digital data.
A built-in converter converts the cooling water temperature and the engine speed into digital data at regular intervals, and outputs the digital data to the central processing unit 7.

The electronic control unit 6 determines the opening time of the fuel injection valve using the respective signals from the intake pressure sensor 13 and the rotation speed sensor 14 as main information, controls the fuel injection valve 5 based on the determination, and controls the engine. A program for injecting fuel corresponding to the load from the fuel injection valve 5 to the intake system 1 is stored. Further, the amount of intake air passing through the bypass passage 3 is adjusted by controlling the opening of the flow control valve 4 provided in the bypass passage 3 bypassing the throttle valve 2 based on at least a change in the engine speed NE.
The engine speed NE during idling is controlled so as to gradually approach the idle target speed NEa. The engine speed NE is detected, and the deviation α between the detected engine speed NE and the idle target speed NEa at that time is determined. Is calculated based on the deviation α, and the flow control valve 4 is opened according to the opening corrected by the determined correction value . Engine times
Flow control if the number of revolutions NE is higher than the set number of revolutions
The calculation cycle of the correction value of the valve 4 is set by the engine speed NE.
By making it shorter than when the rotation speed is lower than the
A program programmed to increase the change rate of the correction amount is also incorporated.

FIG. 2 shows a schematic configuration of the idle speed control program. In this program, the operation duty ratio DISC is calculated by the following equation.

DISC (%) = DAAV + DSTA + DFB + K (1) DFB _n = DFB _n−1 + FKISC (2) where DAAV is a water temperature correction amount, DSTA is a start time correction amount, DFB is a rotation feedback correction amount, and K is another electric load. FKISC is a correction value set by the deviation α, for example, in the case of a change due to the variation of

Based on the above equation, the calculation duty ratio DIS
The calculation of C is programmed to be performed, for example, every few milliseconds. Further, the correction value FKISC is calculated based on a calculation cycle when the engine speed NE is lower than the set speed, and when the engine speed NE is higher than the set speed, the correction value FKISC is calculated, for example, every 1/2 of the case where the engine speed NE is lower. Is done. That is, when the engine speed NE is higher than the set speed, the correction value FKISC is calculated in a half cycle as compared with the case where the engine speed NE is low, and the change speed (change rate) is programmed so as to be doubled. I have. Correction value F at each time
The KISC is stored in a table set in advance in the storage device 8 with respect to the typical value of the deviation α, and the deviation α not found in the table is obtained by interpolation calculation. In the case of this embodiment, the deviation α and the correction value FKIS
The relationship with C is shown in FIG. That is, when the deviation α is positive, that is, when the engine speed NE exceeds the idle target speed NEa, the correction value FKISC
Is set to a negative value, while in the opposite case, the correction value FKISC is set to a positive value.

First, at step S1, the engine speed NE at this time is detected. In step S2, the detected engine speed NE and the idle target speed N at that time are set.
The deviation α from Ea is calculated. In step S3, it is determined whether or not the detected engine speed NE exceeds the determination reference speed NEs.
The process proceeds to step S5 when exceeding. This reference rotation speed NEs is 2000 r in this embodiment.
pm, but may be the number of revolutions before and after this depending on the engine. Step S4 is a process when the engine speed NE is lower than 2000 rpm, and calculates the rotation feedback correction amount DFB by the above equation (2) at every 2T millisecond calculation interval. In the calculation of the rotation feedback correction amount DFB, a correction value FKISC is calculated based on the deviation α calculated in step S2, and the obtained correction value FKISC is added to the previously calculated rotation feedback correction amount DFB _n-1 . calculates a present rotational feedback correction amount DFB _n. Similarly, in step S5, a rotation feedback correction amount DFB is calculated by the above equation (2) every T milliseconds. T is longer than the calculation timing of the calculation duty ratio DISC.
The time may be set to 0 times.

In the above configuration, when the engine speed NE exceeds 2000 rpm and deviates from the target idle speed NEa in the idling operation state, the control is performed from step S 1 → step S 2 → step S 3 → Proceeding to step S5, the rotation feedback correction amount DFB is calculated every T milliseconds. When the state where the engine speed NE exceeds 2000 rpm continues, the calculated rotation feedback correction amount DFB does not change until the next calculation. Used for calculating the ratio DISC. Therefore, during the period when the engine speed NE is higher than the idle target speed NEa, the calculation duty ratio D
The ISC indicates that the rotation feedback correction amount DFB is equal to the correction amount F.
Since it becomes smaller by KISC, it is reduced.

Thereafter, the engine speed NE decreases to 2
000 rpm or less and if there is a deviation α, the control proceeds from step S1 to step S2 to step S2.
3 → Proceed to step S4 to calculate the rotation feedback correction amount DFB every 2T milliseconds. In other words, when the engine speed NE becomes 2000 rpm or less, the calculation of the rotation feedback correction amount DFB is performed at twice the interval when the engine speed exceeds 2000 rpm, and even if the deviation α changes during that time, the rotation feedback correction is actually performed. Quantity DF
B changes 2T milliseconds after the previous calculation.
This means that the change speed of the rotation feedback correction amount DFB when the engine speed NE is 2000 rpm or less is １ ／ of that when the engine speed NE exceeds 2000 rpm, and accordingly, the correction of the calculation duty ratio DISC is gradual. This is done to prevent abrupt correction in the case of low rotation. On the other hand, when the engine speed NE exceeds 2,000 rpm, the rotation feedback correction amount DFB changes at a speed twice as low as that at the time of low rotation, and the intake air amount substantially required at the time of high rotation is reduced. The flow control valve 4 is controlled by increasing the response speed to a change in the engine speed NE so as to pass through the bypass passage 3. FIG. 4 shows a case where the deviation α changes at a constant value in such a change in the engine speed NE.

Therefore, when the engine speed NE is less than 2000 rpm, the opening degree of the flow control valve 4 is gently changed in accordance with the change of the deviation α when the engine speed NE is less than 2000 rpm, and exceeds 2000 rpm. If so, the speed is changed at twice the speed in the following case, so that the amount of intake air corresponding to the engine speed NE at that time can be supplied to the surge tank 12 via the bypass passage 3. Therefore, even when the engine speed NE is high, the amount of air taken in from the bypass passage 3 is small enough to gradually approach the idle target speed NEa, and effectively acts on the engine speed NE.

The present invention is not limited to the embodiment described above. For example, in the above embodiment,
The example in which the interval for calculating the rotation feedback correction amount DFB is changed with the engine speed 2000 rpm as a boundary has been described. However, as shown in FIG. 5, a coefficient which increases in proportion to the engine speed NE is set, and the coefficient is set. By multiplying the correction value FKISC set corresponding to the deviation α,
Determining a correction value FKISC _n for each engine speed NE, by adding the correction value FKISC _n to the previous rotation feedback correction amount DFB, it may be one that calculates the current rotational feedback correction amount DFB. By using such a coefficient, the configuration can be simplified as compared with a case where the correction value FKISC is set corresponding to each engine speed NE and the table is stored in the storage device 8. .

In addition, the configuration of each section is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0021]

As described in detail above, the present invention determines a correction value based on the level of the engine speed and the magnitude of the deviation α and corrects the opening of the flow control valve based on the correction value. Therefore, the opening of the flow control valve can always be corrected at substantially the same correction speed, and the time required to reach the idle target rotation speed can be made uniform.

[Brief description of the drawings]

FIG. 1 is a schematic structural explanatory view showing one embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of the embodiment.

FIG. 3 is a graph showing a relationship between a correction value and a deviation according to the embodiment.

FIG. 4 is a graph showing a relationship between a calculation interval of a correction value and an engine speed according to the embodiment.

FIG. 5 is a graph showing a relationship between a calculation interval and an engine speed according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Intake system 2 ... Throttle valve 3 ... Bypass passage 4 ... Flow control valve 6 ... Electronic control device 7 ... Central processing unit 8 ... Storage device 9 ... Input interface 11 ... Output interface

Claims (1)

(57) [Claims] An idle flow is controlled by controlling an opening of a flow control valve provided in a bypass passage bypassing a throttle valve based on at least a change in engine speed to adjust an amount of intake air passing through the bypass passage. This is an idle speed control method that controls the engine speed to approach the idle target speed.The engine speed is detected, and the deviation between the detected engine speed and the idle target speed at that time is calculated. A correction value for the opening of the flow control valve is determined based on the deviation, the flow control valve is opened according to the opening corrected by the determined correction value , and the detected engine speed is set. Higher than the rotating speed
In this case, the calculation cycle of the correction value
Should be shorter than when the speed is lower than the set speed
A change speed of the correction amount is increased by using the method.