JPH06146971A - Control of idle rotation speed - Google Patents

Abstract

PURPOSE:To stabilize engine rotation by restricting variation in the duty ratio of flow control valve opening by determining the increasing amount of rotation correction based on the difference between engine rotation speed and aimed rotation speed. CONSTITUTION:Engine rotation speed at the time of idling is detected to control the rotation speed by controlling the opening of a flow control valve 4 provided on a bypass route 3 for bypassing a throttle valve 2, based on variation in the pressure of an intake system 1 as well as in the engine rotation speed, and whereby adjusting the amount of intake air, by an electronic controller 6. A difference between the detected engine rotation speed and an aimed idle rotation speed at the time is calculated, and the increasing amount of rotation correction is determined based on the calculated difference, and a duty ratio of the opening of the flow control valve 4 is determined based on the increasing amount of correction and the increasing amount of rotation correction corresponding to the variation in the pressure. Even when the engine rotation speed and intake air tube pressure are abruptly changed, the calculated duty ratio is not changed following the speed variation, and no stalling thus happens during racing and the like.

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 Conventionally, in this type of idle speed control method, a plurality of bypass passages bypassing a throttle valve are provided, as in the engine idle speed control device disclosed in Japanese Patent Laid-Open No. 2-102337. It is known that a valve is provided in the bypass passage and the intake air amount is adjusted by the opening degree of the valve to stabilize the engine rotation during idling. The valve of the bypass passage is configured such that the opening degree is controlled so that the engine speed approaches a target value, or the opening degree increases as the engine temperature decreases.

[0003]

In the structure described above, a so-called temperature sensitive valve, which operates a valve mechanism with bimetal or wax, is used to adjust the amount of intake air during warm-up operation. Has been done. However,
Such a temperature-sensitive valve cannot be controlled by a drive signal from an electronic control unit like a solenoid valve normally used in such a passage, and therefore, the intake valve is not always appropriate for the engine temperature. It is not always open to supply the amount of air, and the control accuracy is often low.

Therefore, it is conceivable that the solenoid valve is used instead of the temperature sensing valve to adjust the intake air amount to one unit. In this case, if the electronic control unit attempts to control the solenoid valve, the intake air amount must be corrected by the engine speed and the intake pipe pressure before returning to the idle operation after racing, engine braking, or the like. There are cases where it does not. However, in a system in which the temperature-sensing valve is replaced by a solenoid valve, this solenoid valve also controls the warm-up correction amount increase during warm-up operation, so even during warm-up operation, correction by intake pipe pressure is possible. When performed, the engine rotation may not be stable due to the ever-changing intake pipe pressure.

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

[0006]

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 controls the opening degree of the flow rate control valve provided in the bypass passage bypassing the throttle valve based on the change in the pressure of the intake system and the change in the engine speed. It is an idle speed control method that controls the engine speed during idling by adjusting the intake air amount, and detects the engine speed, and detects the engine speed and the idle target speed at that time. The difference is calculated, the rotation correction increase amount is determined based on the calculated difference, and the duty ratio of the opening of the flow control valve is determined based on the correction increase amount according to the change in the pressure and the rotation correction increase amount. Characterize.

[0007]

With this structure, the opening degree of the flow control valve in the bypass passage bypassing the throttle valve is adjusted based on the difference between the engine rotation speed and the target rotation speed to increase the rotation correction amount and the intake system. It is determined by the correction increase according to the pressure change. That is, the rotation correction increase amount is not determined according to the detected engine rotation speed, and therefore the rotation correction increase amount does not become extremely large even when the engine rotation speed during warm-up operation is high. Therefore, for example, even if the pressure change occurs due to racing or the like during warm-up operation, and the correction increase according to the pressure change is performed, the duty ratio of the opening of the flow control valve does not change significantly, The rotation can be stabilized.

[0008]

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. The 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. 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. Then, 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 4,
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 fuel cut from the fuel injection valve 5 to the intake system 1 is built in. Also, the throttle valve 2
By controlling the opening degree of the flow rate control valve 4 provided in the bypass passage 3 that bypasses the intake air passage on the basis of the change in the pressure of the intake system 1 and the change in the engine speed, the intake air amount is adjusted. In order to control the engine speed of
The engine speed is detected, the difference between the detected engine speed and the idle target speed at that time is calculated, and the rotation correction increase amount is determined based on the calculated difference, and the correction increase amount is calculated according to the change in the pressure. Also, a program programmed so as to determine the duty ratio of the opening degree of the flow control valve based on the rotation correction increase amount is also incorporated.

The 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.

DISC (%) = DAAV + DAPP + DFB + K (1) where DAAV is the water temperature correction amount, DAPP is the E / G rotation load correction amount, DFB is the rotation feedback correction amount, and K is
Is a correction amount in the case of other changes in electric load.

The E / G rotational load correction amount DAPP is determined by adding the rotational correction amount DNE and the intake pipe pressure correction amount DLL.

DAPP = DNE + DLL (2) The rotation correction amount DNE is calculated by the rotation correction amount table described later, and the intake pipe pressure correction amount DLL is 0 when the idle switch 16 outputs the LL signal d. , Is set to increase as the intake pipe pressure increases.

Further, the rotation feedback correction amount DFB is the degree of increase according to the engine speed NE,
It is determined by the fed back engine speed NE.

First, at step 51, the rotation speed sensor 1
The rotation speed NE of the engine is detected by the rotation speed signal b output from the motor vehicle 4. At step 52, the difference D between the detected rotational speed NE and the target rotational speed NESET at that time
Calculate ef. The target rotation speed NESET is calculated based on the cooling water temperature at that time. In step 53, the rotation correction amount DNE is calculated from the rotation correction amount table based on the calculated difference Def. As shown in FIG. 3, the data of the rotation correction amount table is created on the basis of the data that linearly increases with the rotation correction amount DNE when the difference Def is α being 0, and is, for example, three data. Is set in advance, and data between each data is obtained by interpolation.

In the above structure, for example, when racing is performed, the throttle valve 2 which is fully closed during idle operation is opened, so the engine speed N
Surge tank 1 which is intake pipe pressure as E rises
Since the pressure of 2 fluctuates, the E / G rotation load correction amount DAPP is required when calculating the calculation duty ratio DISC. After the racing, when the engine speed NE decreases, the control proceeds to steps 51 → 52 → 53 to determine the rotation correction amount DNE based on the difference Def.
Then, the E / G rotation load correction amount DAPP is calculated from the determined rotation correction amount DNE and the intake pipe pressure correction amount DLL, and the calculation duty ratio DISC is calculated using the E / G rotation load correction amount DAPP. To do. At this time, if the warm-up operation is being performed, the water temperature correction amount DAAV corresponding to the cooling water temperature at that time is added to the E / G rotational load correction amount DAPP,
Further, during feedback control, the rotation feedback correction amount DFB is added to the E / G rotation load correction amount DAPP and the water temperature correction amount DAAV, and the calculated duty ratio DI
SC is determined.

As described above, the rotation correction amount DNE is calculated from the difference Def between the engine speed NE and the target speed NESET.
Therefore, the engine rotation does not change significantly even during the warm-up operation. That is, even if the engine speed NE and the intake pipe pressure change rapidly, the calculated duty ratio DISC does not change following the speed of change, so the engine speed NE does not change rapidly. The engine will no longer stall during racing or engine braking.

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.

[0023]

As described in detail above, according to the present invention, the rotation correction increase amount is determined based on the difference between the engine speed and the target speed. Therefore, the rotation speed is increased based on the engine speed at that time. Compared with the case where the correction increase is determined, the amount of change in the rotation correction increase is small, and therefore, the fluctuation of the duty ratio of the opening of the flow control valve is suppressed to a small extent without being affected by the correction increase corresponding to the change in pressure. Therefore, the rotation of the engine can be prevented from becoming unstable even during warm-up.

[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 data for a rotation correction table of the same embodiment.

[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 is adjusted by controlling an opening of a flow control valve provided in a bypass passage bypassing a throttle valve based on a change in intake system pressure and a change in engine speed. , An idle speed control method for controlling the engine speed during idling, in which the engine speed is detected, the difference between the detected engine speed and the idle target speed at that time is calculated, and the calculated difference is calculated. Based on the rotation correction increase amount and the rotation correction increase amount according to the change in the pressure, and the duty ratio of the opening of the flow control valve is determined based on the rotation correction increase amount. .