JPH08312430A - Idling engine speed control method - Google Patents

Abstract

PURPOSE: To suppress an error leaning, and to prevent an engine stall and a racing of the engine speed, by deciding the applying of a load depending on the variation of the engine speed, and prohibiting the learning of the intake air amount when the applying of the load is detected. CONSTITUTION: In a bypass passage 3 to detour a throttle valve 2, a flow rate control valve 4 for idling engine speed control is provided, an the idling engine speed is maintained at an object speed by regulating the opening of the valve 4 by an electronic control device 6. In this case, the opening timing is decided by making the output signals of a intake air pressure sensor 13 and a speed sensor 14 as the main signal. And the opening of the flow rate control valve 4 is controlled depending on the variation of the engine speed, and the intake air amount is to be leaned. And the engine speed when a load such as an air conditioner is applied is detected, the applying of the load is detected depending on the engine speed detected this time, and the average value of the engine speed, and when the applying of the load is decided, the learning of the intake air amount is to be prohibited.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as this type of idle speed control method, a control for recognizing an appropriate air amount in an idle operation state from a feedback correction amount and learning a learning value based on the feedback correction amount is performed. Is. As shown in FIG. 3A, learning is prohibited when the engine speed fluctuates, and is performed in a state where the engine speed is stable. That is, the learning control is prohibited when the engine speed exceeds the target speed due to a load such as an air conditioner (hereinafter, simply referred to as an air conditioner) or a headlight. Also, for example,
As described in JP-A-5-195847,
When the load on the engine is changing,
It is known that the learning of the control amount of the control valve arranged in the bypass passage bypassing the throttle valve of the engine is prohibited until the change of the load becomes substantially stable around a predetermined set value. In such idle speed control, it is determined whether or not an electric load such as an air conditioner or a headlight as a load is turned on based on an on / off state of switches of the electric load.

[0003]

By the way, in addition to the electric load as described above, the load on the engine is not limited to the above-mentioned electric load, and the air is generated by the operation of the brake or clutch, or the open state of the throttle valve caused by the hysteresis of the on / off of the idle switch. There are also some due to an increase in the amount. With such a load, as shown in FIG. 3B, a signal indicating that the load is applied, such as a load signal generated by turning on / off a switch in an electric load, cannot be obtained. However, the learning control was executed even though the engine speed was not stable, and the learning value was erroneously learned. Therefore,
By controlling the control valve based on the learned value that is erroneously learned, the engine may stall or the rotation of the engine may rise.

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

[0005]

In order to achieve the above object, the present invention takes the following measures. That is, the idle speed control method according to the present invention passes through the bypass passage by controlling 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. It is an idle speed control method that adjusts the intake air amount, controls the engine speed at idling to approach the idle target speed, and learns the intake air amount, which is the engine speed when a load is applied. Detect
It is characterized in that the load input is determined based on the engine speed and the average value of the engine speed detected this time, and learning of the intake air amount is prohibited when the load input is determined.

[0006]

With such a structure, it is possible to detect loads other than the ones that can detect the turning on / off of the switch, such as an electric load, and therefore, the engine speed due to the loads can be detected. Can recognize a stable state. Therefore, learning is prohibited when it is determined that various loads are applied, so that erroneous learning can be suppressed and engine stall and rising of the rotational speed can be prevented.

[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. , Water temperature correction amount DAAV which is the warm-up correction amount, start-up correction amount, rotation feedback correction amount DFB, load correction amount DSET, etc. are determined by addition and subtraction.

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
A water temperature signal e output from the switch, a switch signal indicating ON / OFF of an electric load including an air conditioner (not shown), and the like are input. From the output interface 11, the drive signal f corresponding to the calculated fuel injection time is supplied to the fuel injection valve 5, and the control signal g based on the calculated duty ratio DISC is supplied to the flow control valve 4. , Respectively. Although not shown, the electronic control unit 6 has a built-in A / D converter for converting an input analog signal into digital data, and the cooling water temperature and the engine speed are converted into digital data at regular intervals. Convert
The data is 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. The intake air amount passing through the bypass passage 3 is adjusted by controlling the opening degree of the flow 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 approach the idle target speed, and the intake air amount is learned. The engine speed NE when the load is applied is detected, and the engine speed detected this time is detected. Determine the load application based on NE and the average value of the engine speed,
There is a built-in program that prohibits learning of the intake air amount when it is judged that a load has been applied. The learning method itself is
The description is omitted because it may be widely known.

A schematic structure of this idle speed control program is shown in FIG.

First, in step S1, it is determined whether or not the air conditioner is on. If not, the process proceeds to step S2, and if it is on, the process proceeds to step S9. In step S2, after the air conditioner is switched from on to off, T
It is determined whether or not one hour (second) has elapsed. If T1 time has elapsed, the process proceeds to step S3, and if not, the process proceeds to step S9. In step S3, it is determined whether or not an electric load other than the air conditioner is on. If it is off, the process proceeds to step S4, and if it is on, the process proceeds to step S9. In step S4, it is determined whether or not T1 time has passed after the electric load other than the air conditioner is switched from ON to OFF. If T1 time has passed, the process proceeds to step S5, and if it has not passed. Step S
Move to 9. In each of the steps up to step S4, it is detected whether or not various electric loads including the air conditioner are turned on, and the period in which the engine speed NE is fluctuated due to the electric loads being turned off. It is detecting.

In step S5, it is determined whether or not the idle switch is on. If it is on, the process proceeds to step S6, and if it is off, the process proceeds to step S9.
In step S6, the engine speed NE and the average speed N
The difference from EAVE is calculated, and it is determined whether or not the absolute value of the difference is less than a predetermined value. If it is less than the predetermined value, the process proceeds to step S7, and if it is more than the predetermined value, the process proceeds to step S9. The average rotation speed NEAVE may be calculated by an arithmetic average, and for example, the following formula is preferable.

NEAVE64 _n = (63 × NEAVE6
4 _n-1 + NE) / 64 where NEAVE64 _n is the latest average rotation speed at that time, and NEAVE _{n -1} is the average rotation speed before one ignition.
In this embodiment, the average rotation speed is calculated by the smoothing calculation with the coefficient of 64, but the coefficient is not limited to this value and may be 32 or 16, for example. In step S7, it is determined whether or not a predetermined time T2 (seconds) has passed since the state in which the absolute value of the difference exceeds the predetermined value is changed to a state below the predetermined value. When the predetermined time T2 has passed Proceeds to step S8, and if not elapsed, proceeds to step S9. Step S8
Then, the learning is executed assuming that the learning condition is satisfied. In step S9, learning is prohibited because the learning condition is not satisfied.

In such a configuration, when an electric load such as an air conditioner is turned on in the idle operation state, the learning value of the feedback correction amount is not learned because the learning condition is not satisfied. Further, when the time T1 has not elapsed after the electric load is turned off, the learning of the learning value is similarly prohibited because the engine speed NE is not stable. When the air conditioner is turned on, the control proceeds from step S1 to S9, and when the air conditioner is off and T1 time has not passed since it was turned off,
The control proceeds from step S1 to S2 to S9 to prohibit learning. Further, when the air conditioner is off, and T1 time has elapsed since it was turned off, and the electric load other than the air conditioner is on, the control is
If the process proceeds to steps S1 → S2 → S3 → S9 and the time T1 has not elapsed after the electric loads are turned off, the control proceeds to steps S1 → S2 → S3 → S4 → S9 to prohibit learning. .

On the other hand, when various electric loads including the air conditioner are turned off, and when T1 time has passed since the turning off, for example, by applying a brake or by making a half-clutch state, the engine speed When NE increases, the deviation of the engine speed NE at that time from the average speed NEAVE, that is, the engine speed N
Since the absolute value of the difference between E and the average rotational speed NEAVE is outside the predetermined value, it is detected that the load is applied.
In this case, the control is steps S1 → S2 → S3 → S4.
→ S5 → S6 → S9, and learning is prohibited. Further, when the deviation of the engine speed NE from the average speed NEAVE is within a predetermined value, but the predetermined time T2 has not elapsed after the deviation within the predetermined value, T1 after the electric load is turned off. As if the time has not elapsed, the control is
Steps S1 → S2 → S3 → S4 → S5 → S6 → S7 →
Proceed to S9 to prohibit learning. Then, the learning is executed for the first time when the load is removed and the predetermined time T2 has elapsed, and the control is performed in steps S1 → S2 → S3 → S4.
→ S5 → S6 → S7 → S8
Learning is carried out.

In this way, the input of a load other than the electric load is detected based on the magnitude of the deviation of the engine speed NE from the average speed NEAVE, and the deviation exceeds a predetermined value from a predetermined value. Since the predetermined time T2 has elapsed since the load converged below, learning is prohibited in consideration of the time until the engine speed NE stabilizes after the load is turned off. Therefore, as in the case of the electric load, learning is prohibited while the load is being applied and until the engine speed NE substantially converges to the target speed after the load is removed. The load can be detected without using a switch signal or the like, and erroneous learning of the learned value can be reliably prevented. Moreover, since an incorrect learning value due to erroneous learning is not stored, it is possible to prevent problems such as engine stall and engine speed NE rising.

The present invention is not limited to the embodiment described above.

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]

INDUSTRIAL APPLICABILITY As described in detail above, the present invention can detect loads other than the ones that can detect the turning on and off of the switch, such as an electric load, so that the engine based on those loads can be detected. It is possible to recognize an unstable state of the rotation speed. Therefore, since learning is prohibited when it is determined that various loads are applied, erroneous learning can be suppressed, and engine stall and rising of the rotational speed can be prevented.

[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 an operation explanatory view of a conventional example.

[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 control valve provided in a bypass passage bypassing a throttle valve based on at least a change in engine speed. This is a method for controlling the engine speed when the load is turned on by detecting the engine speed when a load is applied. A method for controlling an idle speed, comprising determining a load application based on an average value of engine speed and an engine speed, and prohibiting learning of an intake air amount when the load application is determined.