JPH0749048A - Idling rotational speed control method - Google Patents

Abstract

PURPOSE:To solve the shortage of an intake air amount by deciding respective warming-up correction increasing amounts by a correcting amount set on the basis of an engine temperature when a detected engine temperature is a prescribed value and less, and by a correcting amount damped per prescribed time when the detected engine temperature is the prescribed value or more. CONSTITUTION:A bypass passage 3 is provided in an intake system 1 in an engine 100 bypassing a throttle valve 2 for opening/closing in response to an acceleration pedal, and a flow amount control valve 4 for controlling idling rotational speed is interposed in the bypass passage 3. The flow amount control valve 4 is formed in the electronically opening/closing type having the capacity of a large flow amount, calculating duty of driving voltage applied on a terminal 4a is controlled, a real opening degree is changed, and the air flow amount of the bypass passage 3 is regulated. Bypass system passages provided opposing to each correction term are integrated normally by one pair of the bypass passage 3 and the flow amount control valve 4, and the calculating duty ratio is decided by regulating the water temperature of a warming-up correction amount, a load, rotation feed back, a correction amount, and the like. The flow amount control valve 4 provided in the intake system 1 is controlled by an electric control device 6 so as to prevent generation of engine stall, and improve vibration characteristic at the time of idling.

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.

From the above, it has been considered to adjust the intake air amount by using a solenoid valve instead of the temperature sensing valve. In a system having a solenoid valve in the bypass passage, the solenoid valve is controlled by a total amount of respective correction amounts set in consideration of engine cooling water temperature, load, operating state and the like. In such a correction amount, the water temperature correction amount set according to the cooling water temperature becomes large when the cooling water temperature is low, becomes small as the cooling water temperature becomes high, and becomes 0 at the set temperature. It is set.
However, in the warming-up state, even if the cooling water temperature rises to the set temperature and the water temperature correction amount becomes 0, the temperature of the lubricating oil of the engine and the automatic transmission still rises sufficiently at that time. Not
The engine friction is high. Therefore, if the water temperature correction amount is set to 0 in this state, the intake air amount becomes insufficient, and the engine speed does not reach the target speed, which causes engine stall and vibration.

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, in the idle speed control method according to the present invention, a flow rate control valve is provided in a bypass passage bypassing the throttle valve, and the opening degree of the flow rate control valve is set to a correction increase amount including at least a warm-up correction increase amount based on the engine temperature. It is an idle speed control method that controls the engine speed during idling in the warm-up process by controlling the intake air amount based on the control based on In the following cases, the warm-up correction increase amount is determined based on the correction amount that is set based on the engine temperature. It is characterized in that a correction increase is determined.

In the present invention, the engine temperature may be measured not only by directly measuring the temperature of the engine itself but also by measuring cooling water temperature of the engine, lubricating oil temperature, intake air temperature and the like.

[0008]

With such a structure, the warm-up correction amount is increased by the correction amount set based on the engine temperature when the engine temperature is equal to or lower than the predetermined temperature. If it exceeds, it is determined by the correction amount that decays every predetermined time, and the opening of the flow control valve in the bypass passage is controlled based on the correction increase amount that includes the determined warm-up correction increase amount. The amount is adjusted. That is, the opening degree of the flow control valve is controlled at least according to the engine temperature until the engine temperature exceeds the predetermined temperature, and when it exceeds the predetermined temperature, it does not depend on the engine temperature and becomes 0 at that time. Control is performed so that the intake air amount decreases with the passage of time. Therefore, if the operating state of the engine exceeds a predetermined temperature, the intake air amount is adjusted regardless of the engine temperature, so even if the temperature of the lubricating oil does not rise sufficiently during warm-up operation, It is possible to secure an intake air amount that can be maintained at a certain number.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

An engine 100 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). A bypass passage 3 for bypassing is provided, and a flow rate control valve 4 for idle speed control is provided in the bypass passage 3. Flow control valve 4
Is an electronic switching type that is abbreviated as large flow rate VSV, and its substantial opening can be changed by controlling the operation duty ratio DISC of the drive voltage applied to its terminal 4a. The air flow rate of the bypass passage 3 can be adjusted by means of. That is,
By the set of the bypass passage 3 and the flow control valve 4, the bypass passage which is normally provided for each correction item is unified, and the calculated duty ratio DISC includes them. Water temperature correction amount D, which is the warm-up correction increase
It is determined by adding and subtracting AAV, load correction amount DSET, rotation feedback correction amount DFB, 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 is provided with a rotation speed sensor 14 for detecting the intake pressure signal a output from the intake pressure sensor 13 for detecting the pressure in the surge tank 12 and the engine speed NE.
The rotation speed signal b output from the vehicle, the vehicle speed signal c output from the vehicle speed sensor 15 for detecting the vehicle speed, and the idle switch 1 for detecting the open / closed state of the throttle valve 2.
The LL signal d output from the controller 6, the water temperature signal e output from the water temperature sensor 17 for detecting the engine cooling water temperature as the engine temperature, and the like are input. Further, from the output interface 11, a drive signal f corresponding to the calculated fuel injection time is supplied to the fuel injection valve 5, and a calculated duty ratio DIS to be described later is supplied to the flow rate control valve 4.
The control signal g based on C is output. In addition,
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 has a cooling water temperature and an engine speed N.
The E is 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 load. The program for injecting the fuel corresponding to the above from the fuel injection valve 5 to the intake system 1 is built in. In addition, the opening degree of the flow control valve 4 is controlled based on at least the correction increase amount including the water temperature correction amount DAAV based on the cooling water temperature as the engine temperature to adjust the intake air amount, so that the idling time during the warm-up process is controlled. The engine speed NE is controlled, the cooling water temperature is detected, and when the detected cooling water temperature is equal to or lower than a predetermined value, the water temperature correction amount D is set by the correction amount DAAVh set based on the cooling water temperature.
AAV is determined, and if the detected cooling water temperature exceeds a predetermined value, a correction amount DAAVt that is attenuated at predetermined time intervals.
A program programmed to determine the water temperature correction amount DAAV is also incorporated. It should be noted that the rotational feedback correction increase is the degree of increase according to the engine speed NE. For example, during idle, fuel cut during deceleration is not performed, and the vehicle speed is 2 km / h.
In the following, it is assumed that feedback control is executed and calculated when all of the intake pressure sensor 13, the water temperature sensor 17, and the vehicle speed sensor 15 are operating normally.

The schematic structure of this idle speed control program is shown in FIG. This program is repeatedly executed at predetermined intervals while the idling state is detected. In parallel with this, the operation duty ratio DISC is calculated by the following equation using the water temperature correction value DAAV determined by the correction value DAAV _{(h, t)} determined by this program.

DISC = DAAV + DFB + DSET First, in step S1, the cooling water temperature THW is detected based on the water temperature signal e output from the water temperature sensor 17. In step S2, it is determined whether or not the detected cooling water temperature THW exceeds a set predetermined water temperature THWH. If not, the process proceeds to step S3, and if it exceeds, the process proceeds to step S4. In step S3, the correction value DAAVh corresponding to the detected cooling water temperature THW is searched to determine the water temperature correction value DAAV. The correction value DAAVh is
The lower the cooling water temperature THW, the larger the value is set, and the smaller the cooling water temperature THW, the smaller the cooling water temperature THW. The predetermined water temperature THWH is not set to 0, but is set to a correction amount corresponding to the intake air amount required when the temperature of the lubricating oil of the engine 100 has not risen sufficiently, for example. .

In step S4, it is determined whether or not the elapsed time CDAAV after the cooling water temperature THW exceeds the predetermined water temperature THWH is a predetermined time _TL or more, and if it is above, the process proceeds to step S5, and if it is less than Moves to step S6. In step S5, it determines the water temperature correction value DAAV by the correction value DAAVt based on elapsed time decreases by a predetermined value b at every predetermined time _{T L.} The cooling water temperature TH
When W exceeds the predetermined water temperature THWH for the first time and the predetermined time _TL elapses, the predetermined value b is subtracted from the water temperature correction value DAAV determined by the correction value DAAVh,
After that, the water temperature correction value DAA determined by the previous subtraction processing
It is assumed that the correction value DAAVt is calculated by subtracting the predetermined value b from V, and the water temperature correction value DAAV is determined by the correction value DAAVt. In step S6, the elapsed time CDAAV
The elapsed time CD by counting up the counter that counts
Continue AAV timing. In step S7, the counter is initialized (= 0), that is, the elapsed time CDAAV counted by the counter is set to zero.

In the above structure, the cooling water temperature T after starting
When the HW is lower than the predetermined water temperature THWH, the control proceeds to steps S1 → S2 → S3, the correction value DAAVh corresponding to the preset cooling water temperature THW is searched from the map, and the water temperature correction value is calculated based on the correction value DAAVh. DAAV is determined and the operation duty ratio DISC is calculated. In this state, as in the conventional case, the water temperature correction value DAAV increases as the cooling water temperature THW decreases, and decreases as the cooling water temperature THW increases. Then, when the warm-up operation state advances and the cooling water temperature THW exceeds the predetermined water temperature THWH, the control is
Proceeds to steps S1 → S2 → S4, if the elapsed time CDAAV cooling water temperature THW from exceeding a predetermined temperature THWH is less than the predetermined time _{T L,} the control proceeds to step S6, the cooling water temperature THW is specified temperature THWH Calculation using the water temperature correction value DAAV immediately before exceeding the duty ratio DISC
Is calculated. After this, when the elapsed time CDAAV becomes the predetermined time T _L or more, the control is performed in steps S1 → S2 → S4.
The operation duty ratio DISC is calculated using the water temperature correction value DAAV determined by the correction value DAAVt which decreases as time goes by → S5 → S7.

Thus, the cooling water temperature THW is equal to the predetermined water temperature T
Until the temperature rises to HWH, the water temperature correction value DAAVh that decreases according to the cooling water temperature THW is determined, and the predetermined water temperature THWH is set.
When the cooling water temperature THW becomes higher, the water temperature correction ADAAV is determined by the correction value DAAVt which decreases at a constant rate and used for the calculation of the calculation duty ratio DISC. Even when the end is reached, the calculation duty ratio DISC is the correction value DA.
Since it is corrected by AVt, the intake air amount does not immediately become insufficient. That is, at that time, it is possible to secure a sufficient intake air amount corresponding to the magnitude of the friction of the engine 100 due to the temperature of the lubricating oil of the engine 100. Therefore, the idle speed of the engine 100 can be maintained at the target speed, the stall of the engine 100 can be suppressed, and the vibration characteristic at idling can be improved.

The present invention is not limited to the above-described embodiment, but the temperature of the engine lubricating oil or the intake air temperature may be used as the engine temperature instead of the engine cooling water temperature. .

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 in detail above, according to the present invention, when the engine temperature exceeds the predetermined value, the warm-up correction increase amount is determined by the correction amount that decays at every predetermined time. Even if the actual engine friction due to lubricating oil etc. is large even if it rises, it is possible to eliminate the situation where the intake air amount is insufficient, so even during such a warm-up process, the engine idle speed is kept at the target speed. Therefore, engine stall can be prevented from occurring, and vibration characteristics at idling can be improved.

[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 the same embodiment.

[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

Claims (1)

[Claims] 1. A flow control valve is provided in a bypass passage bypassing a throttle valve, and the opening of the flow control valve is controlled based on at least a correction increase including a warm-up correction increase based on engine temperature to intake air amount. By adjusting
An idling speed control method for controlling the engine speed during idling in the warm-up process, which detects the engine temperature and, when the detected engine temperature is below a specified value, a correction set based on the engine temperature. The idle speed control is characterized in that the warm-up correction increase is determined from the amount, and when the detected engine temperature exceeds a predetermined value, the warm-up correction increase is determined based on the correction amount that decays every predetermined time. Method.