JPS61101634A - Air-fuel ratio controlling method for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent drop of the idling speed at the time of transient operation of an engine, by detecting a fuel increasing or decreasing correction value corresponding to the opening of an idling-speed control valve at the time of rapid opening or closing of the same, and correcting the base injection quantity of fuel on the basis of said correction value. CONSTITUTION:In an apparatus, in which a by-pass intake passage 36 by-passing a throttle valve 16 is provided in an intake system and the opening of a control valve 38 provided in said by-pass intake passage 36 is controlled by controlling the current supplied to a coil 44 by means of a control unit 46, change in the opening of the control valve 38 is detected from the change of the duty ratio of a control signal applied to the coil 44. At the time of rapid opening or closing of the control valve 38, a fuel increasing or decreasing correction value corresponding to the opening of the control valve 38 at the time is calculated, and then the base injection quantity of fuel obtained to suit the operational conditions of an engine is corrected on the basis of the above correction value. An injector 24 is controlled according to the corrected injection quantity of fuel.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an air-fuel ratio control method for an internal combustion engine, and in particular to an internal combustion engine suitable for operating a vehicle engine such as an automobile at an air-fuel ratio that matches the operating conditions. This invention relates to an engine air-fuel ratio control method.

[Conventional technology]

BACKGROUND ART In vehicles such as automobiles, various operating states of the engine are detected, and control is performed to operate the engine at an air-fuel ratio suitable for each operating state. For example, in an engine that uses the D-J system, the basic fuel injection time is determined based on the negative pressure in the intake pipe, and fuel is injected from the injector according to this basic fuel injection time, so that the air-fuel ratio of the mixture is close to the stoichiometric air-fuel ratio. Control is being carried out. Also, a control valve that controls the amount of air passing through the bypass intake passage that bypasses the throttle valve (to maintain the idle speed control valve at the target speed when ringing, or when operating the air conditioner or power steering). In order to increase the idle, the fuel injection time that meets these conditions is calculated from the intake pipe negative pressure, and control is performed to inject fuel at the calculated fuel injection time and maintain the engine speed at a predetermined speed. It is being said.

[Problem that the invention seeks to solve]

However, with the method of calculating the fuel injection time based on the intake pipe negative pressure during idle up control and injecting fuel at the time according to this calculated value, the mixture may become over-lean when the control valve is suddenly opened or closed. , or an overrich problem occurred.

This means that the air conditioner can be turned on from OFF to ON, or from ON to OFF.
When the idle control valve suddenly opens or closes due to As shown in figure (C), the intake pipe negative pressure value taken in by the computer lags behind the opening/closing operation of the idle control valve due to the negative pressure transmission delay due to the physical distance between the idle control valve and the intake pressure sensor. It is caused by change. Moreover, since the fuel injection amount is determined based on the intake pipe negative pressure shown in figure (C), the transient difference between the actual intake air amount shown in figure (b) and (ψ As shown in the figure, lean peaks and rich peaks occur in the air-fuel ratio signal.

In this way, if fuel is injected without correcting the fuel injection time based on the intake pipe negative pressure when the control valve is suddenly opened or closed, the air-fuel mixture will be over-lean (a lean spike will occur in the air-fuel ratio signal). There have been problems in which the engine speed does not follow the transient response due to over-richness (which causes a rich spike in the air-fuel ratio signal) and the idle speed drops transiently.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to prevent the air-fuel mixture from becoming over-lean or over-rich when a control valve is suddenly opened or closed. An object of the present invention is to provide an air-fuel ratio control method for an internal combustion engine that can control the air-fuel ratio of an internal combustion engine.

[Means for solving problems]

In order to achieve the above object, the present invention calculates a basic fuel injection amount based on intake pipe negative pressure or intake air amount, injects fuel with the amount of fuel according to this calculated value, and bypasses the throttle valve. monitors the opening degree of a control valve that controls the amount of air passing through the bypass intake passage, and when the control valve suddenly opens, determines a correction value for fuel increase that is set in association with the valve opening degree at the time of sudden opening; The basic fuel injection amount is increased based on this correction value, fuel is injected with the corrected basic fuel injection amount, and when the control valve is suddenly closed, the fuel is reduced according to the valve opening degree at the time of sudden closing. The basic fuel injection amount is corrected to reduce the basic fuel injection amount using this correction value, and fuel is injected with the corrected basic fuel injection amount.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 3 shows the configuration of a preferred embodiment of the present invention.

In FIG. 3, an air cleaner 12, an intake temperature sensor 14, a throttle valve 16, a negative pressure sensor 18, etc. are arranged in the intake system of the engine 10.
Intake air introduced from the engine is supplied to an intake manifold 22 via a throttle valve 16 and a surge tank 20. The intake manifold 22 is provided with an injector 24 that injects fuel proportional to the injection time. and is supplied into the combustion chamber 28.

The air-fuel mixture in the combustion chamber 28 is ignited by the spark plug 30 and combusted, and the combusted air-fuel mixture becomes exhaust gas and passes through the exhaust valve 32.
is discharged into the exhaust pipe 34 through the exhaust pipe 34.

Further, a bypass intake passage 36 that bypasses the throttle valve 16 is provided in the intake system. This bypass intake passage 36 takes in intake air upstream of the throttle valve 16,
It is configured to guide this intake air to a surge tank 20 downstream of the throttle valve 16. A control valve (ISO valve) 38 that controls the amount of air passing through the bypass intake passage 36 is disposed in the middle of the bypass intake passage 36 . The control valve 38 is composed of a valve body 40, a rod 42 including a magnet part connected to the valve body 40, and a coil 44 disposed opposite to the magnet part, and the valve body 40 is inserted into the bypass intake passage 36. ing. The valve body 40 and the rod 42 operate according to the magnitude of the current supplied to the coil 44, thereby changing the flow cross-sectional area of the bypass intake passage 16 and controlling the amount of intake air passing through.

The amount of current applied to the coil 44 is controlled by a control signal from a control device 46.

Further, the cylinder block 48 of the engine 10 is equipped with a water temperature sensor 50° for detecting the cooling water temperature of the engine 10 and an exhaust pipe 34.
An 02 sensor 52 for detecting the oxygen concentration in the exhaust gas is disposed. Further, a cylinder discrimination sensor 58 and a rotation angle sensor 60 are built into the distributor 56 which distributes the ignition signal from the igniter 54 to each cylinder.

Intake temperature sensor 14, throttle sensor 62 that detects the opening degree of throttle valve 16, negative pressure sensor 18, water temperature sensor 5
0,0. Detection outputs of sensors such as the sensor 52, the cylinder discrimination sensor 58, and the rotation angle sensor 60 that detect various operating states of the engine 10 are supplied to the control device 46.

The control device 46, as shown in FIG.
%RAM72, ROM74, input/output capo-1-76,78
, output ports 80, 81, 82, 83, A/D converter 8
4, multiplexer 86, drive circuits 88, 89, 90,
91 and a waveform shaping circuit 92, each part of which is connected by a pass line 94. and intake temperature sensor 1
4, throttle sensor 62, negative pressure sensor 18, water temperature sensor SO.

The detection output of the 02 sensor 52 is sent to the multiplexer 8.
6, the detected outputs of the cylinder discrimination sensor 58 and the rotation angle sensor 60 are supplied to the waveform shaping circuit 92, and the output of the air conditioner switch 62 is supplied to the input/output port. On the other hand, the output of the drive circuit 88 is connected to the igniter 56, the output of the drive circuit 91 is connected to the coil 44, and the output of the drive circuit 90 is connected to the injector 24.

The control program and various data for calculating fuel injection time are stored in the R,0M74, and the control device 46
The igniter 56 . sends a control signal for operating the engine 10 with a mixture suitable for various operating conditions based on the detection outputs of a group of sensors that detect various operating conditions of the engine 10 .
It is configured to output to the coil 44 and the injector 24. That is, an ignition signal is supplied to the igniter 56, a control signal for controlling the injection time of the injector 24 is supplied to the injector 24, and a control signal for changing the duty ratio is supplied to the coil 44.

In this embodiment, the ROM 74 stores data corresponding to the map shown in FIG. 5 in order to prevent the mixture from becoming over-lean or over-rich when the control valve 38 is suddenly opened or closed. .

This map data is set as a correction value F1 for fuel increase and a correction value F2 for fuel decrease.
l and F2 are set in correspondence with the opening degree of the valve body 40 when the control valve 38 is suddenly opened or closed. That is, the fuel injection amount is set to a value that increases or decreases the amount of fuel by -3 according to the amount of change in the amount of air passing through the bypass intake passage 36 when the control valve 38 is suddenly opened or closed.

In the above configuration, the control device 46 in this embodiment uses the basic fuel injection amount based on the detection outputs of the negative pressure sensor 18 and the intake air temperature sensor 14 in order to inject fuel with the basic fuel injection amount based on the intake pipe negative pressure. The injection time is calculated, a control signal according to this calculated value is given to the injector 24, and the fuel is injected from the injector 24 according to the basic fuel injection time. The basic fuel injection time for the injector 24 is calculated as the injection time to maintain the idle rotation speed at the target rotation speed when idling, and when the air conditioner 96 is operated.
It is determined as the injection time to increase the engine speed at idle.

Here, when the air conditioner signal is taken in, a control signal for rapidly opening and closing the control valve 38 is output to the coil 44. When the control valve 38 is suddenly opened and closed, the IsC routine shown in FIG. 1 is executed.

The I8C routine is a routine that is performed every 30m8, and in this routine, first, as shown in step 200, the deviation ΔDUTY between the current duty DUTY and the previous duty DUTY is calculated based on the control signal supplied to the coil 44. .

Then, the current duty DUTY is set to DUTYO (step 202), and step 204
Proceed to processing. In step 204, a process is performed to obtain a correction value from the map data shown in FIG. That is, based on ΔDUTY calculated in step 200, when the control valve 38 is suddenly opened, the correction value FDUTY is calculated from the correction data F1, and when it is suddenly closed, the correction value FDUTY is calculated from the correction data F2 based on ΔDUTY calculated in step 200. Processing to select the correction value FDUTY is performed. Note that the correction value FDUTY of O is adopted as the correction value except when the control valve 38 is suddenly opened or closed. Correction value FD found in step 204
The value of UTY is used as a correction value for the basic fuel injection time shown in FIG.

That is, when the basic fuel injection time TAU is calculated based on the detection output of the negative pressure sensor 18, the basic fuel injection time TAU is calculated in the TAU calculation routine performed for each synchronous injection.
Processing to correct U is performed. (Step 300) Therefore, in the engineering SC routine, the correction data F for increasing fuel power is
When the correction value FDUTY is selected from 1, T
AU is corrected to increase, and fuel is injected from the injector 24 during this corrected basic fuel injection time TAU.

On the other hand, when the correction value FDUTY is selected from the correction data F2 for fuel reduction in the ISC routine, TAU
is corrected to reduce the amount, and the injector 24 injects fuel at the corrected basic fuel injection time TAU. In addition,
When 0 is selected as the correction value in the ISO routine, the basic fuel injection time based on the detection output of the negative pressure sensor 18 is used as TAU, and fuel is injected from the injector 24 at this TAU.

In this way, in this embodiment, as shown in FIG. 6, a control signal for rapidly opening the control valve 38 is output to the coil 44 at time T1, and a change in the duty ratio of this control signal is set. When the value d1 is exceeded, as shown in figure (d), the fuel injection amount is increased, so the engine speed rapidly increases along with the valve opening command to the coil 44, causing the air-fuel mixture to become over-lean (lean spike). ) can be prevented. Note that in the conventional method, the engine speed changes as shown by the broken line.

Also, at time T2, a signal to close the control valve 38 is given to the coil 44, and when the change in duty ratio becomes less than the set value d, fuel reduction control is performed, and when the valve is commanded to close, It is possible to prevent the air-fuel mixture from becoming overrich, and the engine speed changes as shown in (a). Therefore, according to this embodiment, the sudden opening of the control valve 38,
An excellent effect is that it can prevent lean spikes and rich spikes from occurring in the air-fuel ratio signal when the control valve 38 is suddenly closed, and it can also prevent drivability from decreasing when the control valve 38 is suddenly opened or closed. is obtained.

In the above embodiment, the D-J system was described, but the L-J type engine, which calculates the basic fuel injection amount based on the detection output of the air 70 meter, also has the ability to quickly open and close the control valve. By increasing or decreasing the fuel injection amount according to the deviation in the duty ratio of the control signal that controls the control valve, it is possible to prevent lean spikes and rich spikes from occurring when the control valve suddenly opens or closes. be.

〔Effect of the invention〕

As explained above, according to the present invention, the control valve suddenly opens,
At the time of sudden closing, a correction value for increasing or decreasing the amount of fuel set in association with the valve opening degree at the time of sudden opening or closing is determined, and the basic fuel injection amount is increased or decreased using this correction value. Since fuel is injected at the basic fuel injection amount,
It has the excellent effect of preventing lean spikes and rich spikes from occurring when the control valve suddenly opens or closes, and also prevents a transient drop in idle speed when the control valve suddenly opens or closes. can get.

[Brief explanation of drawings]

FIG. 1 is a flowchart of an I8C routine according to the present invention, FIG. 2 is a flowchart of a TAU calculation routine according to the present invention, FIG. 3 is a block diagram showing an embodiment of a system to which the present invention is applied, and FIG. is a specific configuration diagram of the control device shown in FIG. 3, FIG. 5 is a diagram for explaining the structure of map data, FIG. 6 is a diagram for explaining the operation of the system shown in FIG. 3, and FIG. The figure is a diagram for explaining the operation of the conventional device. 10... Engine, 14... Intake temperature sensor, 16.
...Throttle valve, 18...Negative pressure sensor, 24...
Injector, 36...Control valve, 46...Control device, 50...Water temperature sensor, 52...0. sensor.

Claims (1)

[Claims] (1) Calculate the basic fuel injection amount based on the intake pipe negative pressure or intake air amount, inject fuel with the amount of fuel according to this calculated value, and also calculate the amount of air passing through the bypass intake passage that bypasses the throttle valve. The opening degree of the control valve to be controlled is monitored, and when the control valve opens suddenly, a correction value for fuel increase is determined in correspondence with the valve opening degree at the time of sudden opening, and this correction value is used to adjust the basic fuel injection amount. Inject fuel with the corrected basic fuel injection amount, and when the control valve suddenly closes, calculate a correction value for fuel reduction that is set in association with the valve opening at the time of sudden closing.
An air-fuel ratio control method for an internal combustion engine, characterized in that the basic fuel injection amount is corrected to reduce the basic fuel injection amount based on the correction value, and fuel is injected with the corrected basic fuel injection amount.