JP3035427B2 - 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 Conventionally, in this type of idle speed control method, for example, as described in Japanese Patent Application Laid-Open No. 58-170839, the accelerator pedal is slightly depressed during idling, or a power steering or air conditioner is used. In order to prevent the engine speed from becoming uncontrollable to the target speed when the stepping is canceled or the operation stops from the state where There is known a configuration in which an upper limit value and a lower limit value determined based on a learning value already stored as a control value at the time of idling where feedback control is not performed are provided so that the idle speed does not change more than necessary. ing.

[0003]

Normally, during feedback control in idle speed control, if an attempt is made to maintain the target speed, the correction amount changes in accordance with the temperature of the engine cooling water. It is generally larger in heavy low temperatures than in high temperatures. Since the feedback control is prohibited during traveling, the learning value of the correction amount in the feedback control retains the value before traveling and the value is applied immediately after traveling.

In the above-described configuration, at the time of feedback control, the variable range of the control value is limited by the upper limit value and the lower limit value based on the learning value. When the vehicle enters an idle operation state after traveling in an engine state in which the engine is not running, the learning value in the feedback control uses the value in the engine state before traveling. In this case, the learning value is a value when the cooling water temperature value of the engine is low, and becomes an excessive value in the operating state after the warm-up. Therefore, depending on the state of the engine before traveling, the engine rotation after traveling increases, or conversely, if the rotational speed is corrected to decrease, the engine rotation after traveling decreases or an unstable state is caused. There was a tendency.

[0005] An object of the present invention is to solve such a problem.

[0006]

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 flow rate control valve is provided in the bypass passage bypassing the throttle valve, and the opening degree of the flow rate control valve is set to the learning value as the initial value.
The rotation feedback correction coefficient set by
Controlled by adjusting the amount of intake air and the control value set in accordance with the operating condition of the engine also includes, a idle speed control method for controlling the engine speed during idling, to measure the temperature of the engine, the Rotation feedback
The correction coefficient changes according to the temperature of the engine and learns.
Variable adjustment range of rotation feedback correction coefficient depending on value
The upper and lower sets the limits indicated, indicated by the limit values of the upper and lower
Variable adjustment range as the engine temperature decreases
And the rotation feedback correction coefficient
Is set within the variable adjustment range.

In the present invention, the temperature of the engine
Engine cooling water temperature, lubricating oil temperature, intake air temperature, and the like.

[0008]

With such a configuration, for example, the engine starts running from an idling operation state during warm-up when the engine temperature is still low, and then, after the engine temperature sufficiently rises, the engine is operated again during the idling operation. Is not included in the control value.
Rotation feedback correction where the period value is set by the learning value
Since the upper and lower limits of the coefficient are changed according to the engine temperature, the rotation feedback correction
The variable range of the numbers is different. That is, the variable adjustment range is changed so that the variable adjustment range is not the same between a state where the engine temperature is low such as during warm-up and a state where the engine temperature is sufficiently increased after traveling, and the rotation feedback correction coefficient. Will not exceed the upper limit value and become abnormally large with respect to the temperature of the engine at that time, or conversely, decrease below the lower limit value. In this case, the upper and lower limits are
Set based on learning value, engine temperature drops
The variable adjustment range is expanded according to
Thus, an appropriate variable adjustment range is always maintained. Therefore, even if the feedback control is interrupted during the warm-up and the feedback control is restarted when the temperature of the engine subsequently rises, the control value is limited by the temperature of the engine at the time of the restart, so that the engine speed is abnormal. Ascent and descent can be suppressed.

[0009]

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 which opens and closes in response to an accelerator pedal (not shown), and bypasses the throttle valve 2. Vise passage 3
The bypass passage 3 is provided with a flow control valve 4 for controlling the idle speed. The flow control valve 4 is of an electronic opening / closing type which is abbreviated as a large flow rate VSV, and controls a calculation duty ratio DISC of a drive voltage applied to its terminal 4a, which is a control value. The degree of 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 in the feedback control during idling. And the calculation duty ratio D
The variable range of the ISC is limited so that the correction items such as the rotation feedback correction coefficient DFB and the water temperature correction coefficient do not become extremely large or small when they are added together. The initial value of the rotation feedback correction coefficient DFB is the learning value DL.
This rotation feedback correction is set by the RN.
For coefficient DFB, the upper limit value D, which changes according to the coolant temperature is the temperature of the engine that defines the variable adjustment range
FBMAX (upper limit guard) and lower limit value DFBMIN (lower limit guard) are set.

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 a vehicle speed, an opening signal d output from a throttle sensor 16 for detecting an open / closed state of the throttle valve 2, and an engine temperature as an engine temperature. Water temperature sensor 1 for detecting cooling water temperature
7 is input. From the output interface 11, a drive signal f corresponding to the calculated fuel injection time is supplied to the fuel injection valve 5,
Further, a control signal g based on a calculation duty ratio DISC described later is output to the flow control valve 4. Although not shown, the electronic control unit 6 includes an A / D converter for converting an input analog signal into digital data, and converts the pressure signal h, the water temperature signal e, and the like into digital data at regular intervals. The data is converted into data and output to the central processing unit 7.

The electronic control unit 6 determines the opening time of the fuel injection valve 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 based on the determination to control the load. A program for injecting the fuel corresponding to the fuel injection from the fuel injection valve 5 into the intake system 1 is stored. In addition, a flow control valve 4 is provided in a bypass passage 3 that bypasses the throttle valve 2, and the opening degree of the flow control valve 4 is adjusted by a rotation filter whose initial value is set by a learning value DLRN.
A feedback correction coefficient DFB, which controls at least an intake air amount by controlling with a control value set in accordance with an operation state of the engine, and controls an engine speed during idling. Rotating
The feedback correction coefficient DFB changes according to the temperature of the engine, and the feedback feedback coefficient DFB changes according to the learning value DLRN.
Tsu sets the limit value of the vertical indicating the variable range of adjustment of the click correction coefficient DFB, a variable adjustment range indicated by the limit values of the upper and lower
Expanding as the engine temperature decreases
In addition, the rotation feedback correction coefficient DFB is
A program programmed to set within the adjustment range is also included. In this program, a map in which candidate values of the control value upper limit value DFBMAX and the lower limit value DFBMIN are set in the storage device 8 for every 10 ° C. of the engine coolant temperature, for example, Performs interpolation calculation to set a candidate value. As shown in FIG. 3, the upper limit value DFBMAX and the lower limit value DFBMIN indicate the difference between the learning value DLRN and the upper and lower limits of the variable adjustment range of the rotation feedback correction coefficient DFB. It does not indicate the lower limit.

FIG. 2 shows a schematic configuration of the idle speed control program.

In this program, the intake air amount is controlled by adjusting the opening degree of the flow control valve 4 by the calculated duty ratio DISC so that the idle speed always becomes the target speed depending on the operation state of the engine. . The calculation duty ratio DISC is changed in accordance with the operating condition of the engine. However, the variable control range of the rotation feedback correction coefficient DFB used for calculating the calculation duty ratio DISC is controlled by feedback control. The range is limited to a predetermined range depending on the level of the cooling water temperature of the engine when the engine is running.

When this program is executed,
It is determined whether or not the vehicle is idling,
For example, a rotation speed signal b output from the rotation speed sensor 14
That the engine speed NE based on the engine speed is equal to or less than a predetermined value,
When the opening signal d output from the throttle sensor 16 is on and the throttle valve 2 is fully closed, it is determined that the engine is idling.

Next, first, at step 51, the rotation feedback correction coefficient DFB at this time is set to the learning value DLRN.
It is determined whether the value is less than the value obtained by subtracting the lower limit value DFBMIN from the above. If the value is less than the value, the process proceeds to step 61; In step 61, as the current rotational feedback correction coefficient DFB _n, a value obtained by subtracting the lower limit DFBMIN from the learning value DLRN. On the other hand, in step 52, it is determined whether or not the rotation feedback correction coefficient DFB at this time is greater than a value obtained by adding the upper limit value DFBMAX to the learning value DLRN. If it is below, proceed to step 53 In step 53, as the current rotational feedback correction coefficient DFB _n, setting the rotational feedback correction coefficient _{DFB n-1} of the last time.
In step 62, as the current rotational feedback correction coefficient DFB _n, the upper limit DFBMAX the learning value DLRN
Set the value to which.

That is, if the feedback control is being performed and the current speed feedback correction coefficient DFB is below the lower limit of the variable adjustment range, the control proceeds from step 51 to step 61, and The rotation feedback correction coefficient DFB _n is set to the lowest value (= DLRN + D
FBMIN). On the other hand, if the rotation speed feedback correction coefficient DFB at that time is above the lower limit of the variable adjustment range and below the upper limit, the control proceeds to steps 51 → 52 → 53, and the current rotation feedback correction coefficient As the DFB _n , the previous rotation feedback correction coefficient DFB _n−1 is set. If the rotation feedback correction coefficient DFB at that time is higher than the upper limit of the variable adjustment range, the control proceeds from step 51 to step 52.
→ 62, the current rotation feedback correction coefficient DF
_Bn is the highest value that is the upper limit of the variable adjustment range (= DLRN +
(DFBMAX). Thereafter, by adding the other correction coefficient rotation feedback correction coefficient DFB _n which is set by calculating the arithmetic duty ratio DISC, controls the flow rate control valve 4 by the operation duty ratio DISC.

In such a configuration, the upper limit value DFBM
As shown in FIG. 3, the AX and the lower limit value DFBMIN are set to values that change according to the engine coolant temperature around the learning value DLRN. That is, as the cooling water temperature decreases, the lower limit value DFBMIN changes to the upper limit value D
The upper limit value DFBMAX and the lower limit value DFBMIN are set so that the variable adjustment range up to FBMAX is expanded. Therefore, for example, in the feedback control during the warm-up operation in which the cooling water temperature is low, since the variable adjustment range is wide, the value of the rotation feedback correction coefficient DFB increases, and therefore, the operation duty ratio DISC
Is also a large value. On the other hand, if the running is started during such a warm-up operation and the idle operation is started again when the cooling water temperature is sufficiently increased, the idling operation is restarted because the idling feedback control is prohibited during the running. At this point, the rotation feedback correction coefficient DFB during the warm-up operation is adopted. Since such a rotation feedback correction coefficient DFB is too large for the cooling water temperature at that time, by executing step 62, the rotation feedback correction coefficient DFB is reduced to the maximum value of the variable adjustment range, and the engine speed is abnormal. To be high. Therefore, it is possible to prevent an overrun phenomenon in which the idle speed increases and becomes equal to or higher than the target speed.

The present invention is not limited to the embodiment described above. For example, in the above embodiment, the learning value D
Although the upper and lower limits of the variable adjustment range of the LRN have been described, as shown in FIG. 4, the variable adjustment range of the rotation feedback correction coefficient DFB is broadened according to the engine temperature, specifically, when the engine temperature is low. , May be changed so as to become narrower as the height becomes higher . In this case, regardless of the engine temperature,
That is, it may take a constant value from a low temperature to a high temperature.

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.

[0022]

According to the present invention, as described in detail above, the upper and lower limits of the control value of the flow control valve are set in accordance with the temperature of the engine. Even if the control value changes, the control value can be prevented from changing extremely, so that a large change in the engine speed can be prevented, and the control can always be performed at an appropriate target speed. That is, the rotation feedback correction coefficient is
The variable adjustment range is set to increase as the engine temperature decreases.
Is set to the running state during warm-up
Even if the value of the
After returning to the idle mode, it is reduced by the engine temperature.
Within the specified variable adjustment range
Is set, the engine speed rises significantly or
It is possible to prevent falling.

[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 an operation explanatory view of the embodiment.

FIG. 4 is an operation explanatory view of another embodiment of the present invention.

[Explanation of symbols]

 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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-261951 (JP, A) JP-A-60-75329 (JP, A) JP-A-58-170839 (JP, A) 3037 (JP, U) Actually open 63-186950 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/16 F02D 41/04 315

Claims (1)

(57) [Claims] A flow control valve is provided in a bypass passage bypassing a throttle valve, and an opening of the flow control valve is set to an initial value.
Is the rotation feedback correction coefficient set by the learning value
A control to adjust the amount of intake air control value to be set in accordance with the operating state of the at least include engine, a idle speed control method for controlling the engine speed during idling, to measure the temperature of the engine, It changes according to the temperature of the engine with respect to the rotational feedback correction coefficient, the rotation feedback by the learning value
Set the upper and lower limits indicating the variable range of adjustment of the correction coefficient, the variable adjusting range of the engine indicated by the limit values of the upper and lower
As the temperature decreases, it expands and the rotation
An idle speed control method, wherein a feedback correction coefficient is set within the variable adjustment range.