JPH07279725A - Idle speed control method - Google Patents

Abstract

PURPOSE:To uniform a difference in correction speed by engine speed in the case that the engine deviates speed from a target value. CONSTITUTION:An opening of a flow rate control valve 4 which is arranged on a bypass passage 3 bypassing a throttle valve 2 is controlled at least based on variation of an engine speed NE, and the specific volume of intake air passing the bypass passage 3 is adjusted. The engine speed NE at the time of idling is controlled so as to approach an idling target engine speed NEa. The engine speed NE is detected at this time. A deviation alpha between the detected engine speed NE and the idling target engine speed NEa at that time is computed. A correction value of an opening of the flow rate control valve 4 is determined based on the deviation between the detected engine speed NE and the deviation alpha. The flow rate control valve 4 is opened according to an opening corrected through the determined correction value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an idle speed control method for an automobile engine.

[0002]

2. Description of the Related Art In a conventional idle speed control method, a target speed for idling is set and the target speed and actual speed are set, as in the engine speed control device disclosed in Japanese Patent Laid-Open No. 3-50358. 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. Feedback control is known. In such feedback control of the air control valve, the control amount is usually set to be large in order to match the target rotation speed as quickly as possible when the deviation becomes large. Therefore, there will be no difference between the time from the state where the target rotational speed greatly deviates to the target rotational speed and the time from the state slightly deviating from the target rotational speed until the coincidence. There is.

[0003]

On the other hand, it is known that the absolute amount of intake air is large even when idling when the engine speed is high. This means that in the case where the feedback control as described above is performed, there is the air amount obtained by controlling the opening degree according to the control amount when the engine speed is low, and the above when the engine speed is high. Even if the amount of air by the controlled variable is the same,
Since the required air amount is large when the engine speed is high, the ratio of the obtained air amount contributing to the rotation is smaller than that when the engine speed is low. In other words, regardless of whether the engine speed is high or low, even if the time required to correct the engine speed to the target speed is made uniform, the proportion of the air amount controlled by the air control valve that contributes to the rotation is different, so it is uniform. Sometimes it can't be time.

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

[0005]

The present invention takes the following means in order to achieve such an object. That is, the idle speed control method according to the present invention is configured to control the opening degree of the flow rate control valve provided in the bypass passage bypassing the throttle valve based on at least the change in the engine speed so that the intake passage passing through the bypass passage is controlled. An idle speed control method for adjusting the amount of air and controlling the engine speed during idling to approach the idle target speed, wherein the engine speed is detected,
The deviation between the detected engine speed and the idle target speed at that time is calculated, and the correction value of the opening degree of the flow control valve is determined based on the detected engine speed and the deviation,
The flow control valve is opened according to the opening corrected by the determined correction value.

[0006]

With this structure, the opening of the flow control valve is corrected by the correction value based on the deviation between the engine speed, the engine speed, and the idle target speed. Even if the deviation is the same, the correction value is different between the high value and the low value. That is,
When the deviations are the same, it is possible to increase the correction value when the engine speed is high compared to when the engine speed is low, and change the opening of the flow control valve due to the difference in engine speed at that time. Then, it is possible to adjust the intake air amount that contributes to the rotation to the same extent at that time. This makes it possible to equalize the time until the idle target rotation speed is reached.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 an intake system 1 thereof is provided with a throttle valve 2 which 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 idle speed control is provided in the bypass passage 3. The flow rate control valve 4 is of an electronic opening / closing type, which is abbreviated as a large flow rate VSV, and has a calculated duty ratio DIS of a drive voltage applied to its terminal 4a.
By controlling C, it is possible to change its substantial opening degree, and thereby the air flow rate of the bypass passage 3 can be adjusted. In other words, a set of the bypass passage 3 and the flow rate control valve 4 unifies the bypass passage that is normally provided for each correction item, and the duty ratio DISC includes them. Is determined by adding or subtracting the water temperature correction amount DAAV which is the warm-up correction increase amount, the start-up correction amount, the rotation feedback correction amount DFB, the load correction amount DAPP, and the like.

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

The electronic control unit 6 includes a central processing unit 7
And a storage device 8, an input interface 9, and an output interface 11 are mainly configured. 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 rotation speed output from a rotation speed sensor 14 for detecting the engine speed NE. Signal b, vehicle speed signal c output from vehicle speed sensor 15 for detecting vehicle speed, LL signal d output from idle switch 16 for detecting the open / closed state of throttle valve 2, engine coolant temperature as engine temperature Water temperature sensor 17 for detecting water
The water temperature signal e or the like output from is input. Further, from the output interface 11 to the fuel injection valve 5,
The drive signal f corresponding to the calculated fuel injection time is supplied to the flow control valve 4, and the calculated duty ratio D described later is used.
A control signal g based on ISC is output. Although not shown, the electronic control unit 6 includes an A / D for converting an input analog signal into digital data.
A converter is built in, and the cooling water temperature and the engine speed are converted into digital data at regular intervals and output to the central processing unit 7.

The electronic control unit 6 determines the fuel injection valve opening time based on the respective signals from the intake pressure sensor 13 and the rotation speed sensor 14 as main information, and controls the fuel injection valve 5 by the determination to control the engine. A program for injecting fuel according to the load from the fuel injection valve 5 into the intake system 1 is built in. Further, the intake air amount passing through the bypass passage 3 is adjusted by controlling the opening degree of the flow rate control valve 4 provided in the bypass passage 3 bypassing the throttle valve 2 based on at least the change in the engine speed NE,
The engine speed NE during idling is controlled so as to gradually approach the target idle 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 detected. Is calculated and a correction value for the opening of the flow control valve 4 is determined based on the detected engine speed NE and the deviation α, and the flow control valve 4 is controlled according to the opening corrected by the determined correction value. A program programmed to open is also included.

A schematic structure of this idle speed control program is shown in FIG. In this program, the calculated duty ratio DISC is calculated by the following equation.

[0013] DISC (%) = DAAV + DSTA + DFB + K (1) DFB n = DFB n-1 + FKISC (2) However, DAAV the water temperature correction amount, DSTA is startup correction amount, DFB rotation feedback correction amount, K is other electrical loads And FKISC are correction values set by the deviation α.

Based on the above equation, the calculated duty ratio DIS
The calculation of C is programmed to be performed every few milliseconds, for example. In addition, the correction value FKISC is calculated, for example, at intervals of half of the time when the engine speed NE is lower than the set speed when the engine cycle NE is lower than the set speed, and when it is higher than the set speed. To be done. That is, when the engine speed NE is higher than the set speed, the correction value FKISC is calculated in half the cycle as compared with the case where the engine speed NE is low, and the change speed (change rate) is programmed to be doubled. There is. Correction value F at each time point
The KISC is stored in a table preset in the storage device 8 for the value of the typical deviation α, and the deviation α that is not 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, in 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 detected.
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, and if it is below, step S4.
If it exceeds, the process proceeds to step S5. This determination reference speed NEs is 2000 r in this embodiment.
Although it is pm, depending on the engine, it may be the number of revolutions before and after this. Step S4 is a process when the engine speed NE is lower than 2000 rpm, and the rotation feedback correction amount DFB is calculated by the above equation (2) at every calculation interval of 2T milliseconds. The rotation feedback correction amount DFB is calculated by calculating the correction value FKISC based on the deviation α calculated in step S2, and adding the obtained correction value FKISC to the previously calculated rotation feedback correction amount DFB _n-1 . calculates a present rotational feedback correction amount DFB _n. Similarly, in step S5, the 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, for example,
The time may be set to 0 times.

In the above configuration, when the engine speed NE exceeds 2000 rpm and deviates from the idle target speed NEa in the idling operation state, the control is performed in step S1 → step S2 → step S3 → In step S5, the rotation feedback correction amount DFB is calculated every T milliseconds. The calculated rotation feedback correction amount DFB does not change until the next calculation when the engine speed NE continues to exceed 2000 rpm, and does not change the calculation duty every few milliseconds. Used to calculate the ratio DISC. Therefore, during the period when the engine speed NE exceeds the idle target speed NEa, the calculated duty ratio D
In the ISC, the rotation feedback correction amount DFB is the correction amount F.
It is reduced because it becomes smaller by KISC.

After this, the engine speed NE drops and becomes 2
When the speed is 000 rpm or less and the deviation α exists, the control is step S1 → step S2 → step S
The process proceeds from 3 to step S4, and the rotation feedback correction amount DFB is calculated every 2T milliseconds. That is, when the engine speed NE becomes 2000 rpm or less, the calculation of the rotation feedback correction amount DFB will be performed at an interval twice as long as when the rotation speed exceeds 2000 rpm, and even if the deviation α changes during that period, the rotation feedback correction amount DFB is actually corrected. Amount DF
B changes 2T milliseconds after the previous calculation.
This means that the change rate of the rotation feedback correction amount DFB when the engine speed NE is 2000 rpm or less is 1/2 that when the rotation feedback correction amount DFB exceeds 2000 rpm, and thus the correction of the calculated duty ratio DISC becomes gradual. This is done to prevent abrupt corrections at low speeds. On the other hand, when the engine speed NE exceeds 2000 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 that is substantially required at the time of high rotation is changed. The flow rate control valve 4 is controlled by increasing the response speed to changes 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, the opening degree of the flow control valve 4 is gradually changed according to the change of the deviation α when the engine speed NE is 2000 rpm or less when it deviates from the idle target speed NEa, and exceeds 2000 rpm. If so, the speed is changed twice as fast as in the following case, so that the surge tank 12 can be supplied through the bypass passage 3 with the intake air amount corresponding to the engine speed NE at that time. Therefore, even when the engine speed NE is high, the amount of intake air from the bypass passage 3 is sufficient to cause the intake target air speed NEa to gradually approach the idle target speed NEa, which effectively affects 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 of 2000 rpm as the boundary has been described. However, as shown in FIG. 5, a coefficient that increases in proportion to the engine speed NE is set, and the coefficient is set to Multiplying the correction value FKISC set corresponding to the deviation α,
The correction value FKISC _n for each engine speed NE may be determined, and the correction value FKISC _n may be added to the previous rotation feedback correction amount DFB to calculate the current rotation feedback correction amount DFB. By using such a coefficient, the configuration can be simplified as compared with the 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 part 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 above in detail, the present invention determines the 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 by the correction value. The opening degree of the flow control valve can always be corrected at substantially the same correction speed, so that the time required to reach the idle target speed can be made uniform.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory view showing an 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 same embodiment.

FIG. 4 is a graph showing a relationship between a correction value calculation interval and an engine speed in 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]

 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)

[Claims] 1. An intake air amount passing through a bypass passage is adjusted by controlling an opening of a flow rate control valve provided in a bypass passage bypassing a throttle valve based on at least a change in engine speed, and during idling. This is an idle speed control method that controls the engine speed to approach the idle target speed. It detects the engine speed and calculates the deviation between the detected engine speed and the idle target speed at that time. Then, a correction value for the opening of the flow control valve is determined based on the detected engine speed and the deviation, and the flow control valve is opened according to the opening corrected by the determined correction value. Idle rotation speed control method.