JP2906802B2 - Air-fuel ratio control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-fuel ratio of an air-fuel mixture supplied to a combustion chamber when a deceleration operation state of an internal combustion engine (hereinafter, "internal combustion engine" is sometimes referred to as "engine") is detected. The present invention relates to an air-fuel ratio control device for an internal combustion engine that controls the air-fuel ratio to leaner than the stoichiometric air-fuel ratio.

[0002]

2. Description of the Related Art Conventionally, in a deceleration operation state of an engine (specifically, an operation state in which an engine load state is equal to or lower than a predetermined load level), combustion of an air-fuel mixture deteriorates. Even if feedback control of the air-fuel ratio based on the output of the sensor (O ₂ sensor) is performed, the exhaust gas purification state is not necessarily improved. In such an operating state, it is more efficient to set the air-fuel ratio lean. And HC
In some cases, good results can be obtained from the relationship of reduction of (hydrocarbon) emissions. For this reason, a technique has been proposed in which feedback control of the air-fuel ratio is stopped during deceleration operation and lean setting is performed.

[0003]

[SUMMARY OF THE INVENTION However, in an air-fuel ratio control system of a conventional internal combustion engine as described above, in the operating state of the load condition (e.g. volumetric efficiency and manifold absolute pressure) than the set value of the engine, engine warm-up state in the written <br/> Warazu, because doing the air-fuel ratio setting at a constant lean ratio, not be said necessarily optimum setting state is obtained.

[0004] The present invention has been made in view of such problems, and sets a lean ratio in accordance with a warm-up state of an internal combustion engine.
By allowing a constant, the optimum air-fuel ratio control during deceleration operation was so performed, and an object thereof is to provide an air-fuel ratio control apparatus for an internal combustion engine.

[0005]

SUMMARY OF THE INVENTION Accordingly, the air-fuel ratio control equipment of an internal combustion engine of the present invention, during warm-up of the internal combustion engine base fuel
The injection amount is set large so that the lower the temperature, the more fuel is added.
A correction is made using the specified warm-up increase coefficient,
When the deceleration operation state detection means for detecting the deceleration operation state of the internal combustion engine detects the deceleration operation state of the internal combustion engine, a leaning coefficient is set to correct the basic fuel injection amount.
Thus, air-fuel ratio control means for controlling the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber to a leaner side than the stoichiometric air-fuel ratio is provided, and the air-fuel ratio control means is decelerated while the internal combustion engine is warmed up.
If the internal combustion engine is in a cold state, the temperature of the internal combustion engine is lower when the engine is cold.
The leaning coefficient so that the air-fuel ratio is leaner than during
Is set.

[0006]

[0007]

The air-fuel ratio control apparatus for an internal combustion engine according to the present invention described above.In place
Indicates the deceleration operation state of the internal combustion engine by the deceleration operation state detection means.
Is detected, the leaning coefficient is set by the air-fuel ratio control means.
The air-fuel ratio of the mixture supplied to the combustion chamber
Is controlled to be leaner than the stoichiometric air-fuel ratio
However, in this air-fuel ratio control means, the cooling of the internal combustion engine is also performed.
The leaning coefficient is larger when the engine is running than when it is hot.
SetThe air-fuel ratio of the mixture supplied to the combustion chamber
It is controlled to be leaner than the air-fuel ratio.

[0008]

[0009]

Embodiments of the present invention will be described below with reference to the drawings. (A) Description of First Embodiment FIGS. 1 to 6 show an air-fuel ratio control device for an internal combustion engine as a first embodiment of the present invention, FIG. 1 is a block diagram showing a control system thereof, and FIG. Hardware block diagram of the control system, FIG.
Overall configuration diagram of Rue emissions gin system having a present apparatus, FIG. 4
Are flowcharts for explaining the control procedure, and FIGS.
FIG.

FIG. 3 shows an engine system having the present apparatus. In FIG. 3, an engine (internal combustion engine) EG has an intake passage 2 and an exhaust passage 3 leading to a combustion chamber 1 of the engine. The communication between the intake passage 2 and the combustion chamber 1 is controlled by an intake valve 4, and the communication between the exhaust passage 3 and the combustion chamber 1 is controlled by an exhaust valve 5.

The intake passage 2 is provided with an air cleaner 6, a throttle valve 7, and an electromagnetic fuel injection valve (injector) 8 in this order from the upstream side, and the exhaust passage 3 is provided with an exhaust gas purifier in that order from the upstream side. A catalytic converter (three-way catalyst) 9 and a muffler (muffler) (not shown) are provided. The intake passage 2 has a surge tank 2
a is provided.

Further, the injectors 8 are provided in the intake manifold portion by the number of cylinders. Now, assuming that the engine EG of this embodiment is an in-line four-cylinder engine, four injectors 8 are provided. That is, it can be said that the engine is a so-called multi-point fuel injection (MPI) type multi-cylinder engine. Also, the throttle valve 7
Is connected to the accelerator pedal via a wire cable, so that the opening degree changes according to the depression amount of the accelerator pedal, but further bypasses the portion of the intake passage 2 where the throttle valve 7 is provided. A bypass passage 2b is provided. In the bypass passage 2b,
An idle speed control valve (ISC valve) 41 as a throttle bypass valve and a wax valve 42 are provided side by side.

The ISC valve 41 is an electromagnetic valve.
In response to a control signal from an electronic control unit (ECU) 23, which will be described later, a bypass opening 2b-1 of the bypass passage 2b to the intake passage 2 can be opened and closed.
The bypass opening 2b-2 of the bypass passage 2b to the intake passage 2 can be opened and closed according to the engine temperature detected by the heat-sensitive portion containing the wax.

Thus, even if the accelerator pedal is not depressed during idling, the opening of the ISC valve 41 is adjusted to increase or decrease the amount of intake air flowing through the intake passage 2, thereby controlling the engine speed during idle operation. It can be executed. Further, in order to cope with an increase in friction loss when the engine is cold, the above-mentioned ISC valve 41 is opened at a low temperature to increase the amount of intake air particularly at a low load (this is called a so-called first idle state). .

With such a configuration, the air sucked through the air cleaner 6 according to the opening degree of the throttle valve 7 is mixed with the fuel from the injector 8 at the intake manifold so as to have an appropriate air-fuel ratio. By igniting the spark plug 35 at an appropriate timing, the fuel is burned to generate engine torque, and then the air-fuel mixture is discharged to the exhaust passage 3 as exhaust gas. , NOx are purified, then muffled by a muffler and released to the atmosphere.

Further, various sensors are provided to control the engine EG. First, on the intake passage 2 side, an air flow sensor 11, which detects an intake air amount from Karman vortex information, an intake air temperature sensor 12, which detects an intake air temperature, and an atmospheric pressure sensor 13, which detects an atmospheric pressure, are provided at the portion where the air cleaner is provided. The throttle valve is provided with a potentiometer type throttle sensor 14 for detecting the opening of the throttle valve 7, an idle switch 15 for detecting an idling state, and the like.

An oxygen concentration sensor (air-fuel ratio sensor; O ₂ sensor) for detecting the oxygen concentration (O ₂ concentration) in the exhaust gas is provided in the exhaust passage 3 on the upstream side of the catalytic converter 9.
17 are provided. Further, as other sensors, a water temperature sensor 19 for detecting an engine cooling water temperature, and a crank angle sensor 21 for detecting a crank angle as shown in FIG. 2 (this crank angle sensor 21 is also a rotation speed sensor for detecting an engine rotation speed) A TDC sensor (cylinder determination sensor) 22 for detecting that the first cylinder (also serving as a specific cylinder or a reference cylinder) is at the top dead center is provided in the distributor.

The detection signals from these sensors are input to the ECU 23. In addition,
The ECU 23 is also supplied with a voltage signal from a battery sensor 25 for detecting the voltage of the battery 24 and a signal from a cranking switch 26 or a vehicle speed sensor 20 for detecting the starting time.

The hardware configuration of the ECU 23 is as shown in FIG. 2. The ECU 23 has a CPU 27 as its main part. The CPU 27 has an intake air temperature sensor 12, an atmospheric pressure sensor 13, a throttle sensor 14, detection signals from the O ₂ sensor 17, the water temperature sensor 19, and the battery sensor 25 are input through the input interface 28 and the A / D converter 30, and the detection signals from the idle switch 15, the cranking switch 26, and the vehicle speed sensor 20. Is input via the input interface 29. Also,
Air flow sensor 11, crank angle sensor 21, TDC
A detection signal from the sensor 22 is directly input to an input port of the CPU 27.

Further, the CPU 27 has a ROM for storing program data and fixed value data via a bus line.
While the RAM 32 and the battery 24 are updated and sequentially rewritten, data is exchanged with the battery backup RAM 33 which is backed up by holding the stored contents while the battery 24 is connected.

The data in the RAM 32 disappears and is reset when the ignition switch is turned off. Further, a fuel injection control signal based on the calculation result by the CPU 27 is output to the four injectors 8 (more precisely, transistors for injector solenoids) via the injection driver 34. The control signal for the ISC valve 41 is supplied from the CPU 27 to the ISC valve 41 via the driver 40.

Focusing on fuel injection control (air-fuel ratio control), a control signal for fuel injection calculated by a method described later is output from the CPU 27 to the injector solenoid via the driver 34, and the four injectors 8 are sequentially operated. Although so Yuku so driven, for such a fuel injection control (injector drive time control), ECU 23, as shown in FIG. 1, first, to determine the basic drive time T _B for the injector 8 basic The basic drive time determination means 51 includes information on the intake air amount A from the air flow sensor 11 and the crank angle sensor 21.
Determine the intake air quantity A / N information per engine revolution from the engine speed N information from, is what determines the basic drive time T _B based on this information.

A feedback-time air-fuel ratio correction coefficient setting means 53 for setting a feedback-time correction coefficient P / 2 + I (= K _AF ) according to the result of comparison between the output of the O ₂ sensor 17 and the judgment voltage (reference voltage) is provided. As well as
An air-fuel ratio correction coefficient setting means 54 for setting an air-fuel ratio correction coefficient I + K _AFM (= K _AF ) is provided. Further, switching means 52A and 52B which switch in response to a control signal from a switching control means 57 described later perform switching. The output of one of the feedback-time air-fuel ratio correction coefficient setting means 53 and the air-fuel ratio correction coefficient setting means 54 is selected. In the above, P is a proportional value, I is an integral value, and _KAFM is a coefficient set according to the engine load and the engine speed.

Further, the air-fuel ratio correction coefficient setting means 54
Three I value setting means 54-1 to 54-3, switching means 54
It is configured to include a 4 and K _AFM setting means 54-5. Here, the I value setting means 54-1 determines that I = 1.0
The I value setting means 54-2 sets I = 1.
05, the I value setting means 54-3 reads out a map value I (Tw) (this map stores the characteristics shown in FIG. 5) according to the engine cooling water temperature Tw,
This is set as the I value. Here, it can be seen from FIG. 5 that the I value setting means 54-3 sets the I value smaller when the engine EG is cold than when it is hot. Note that a coefficient indicating the degree of leaning
Is called the leaning coefficient (in this case, the leaning factor
The greater the degree, the greater the leaning coefficient),
As can be seen from the description, when the I value is greater than 1.0,
When the I value is smaller than 1.0, it becomes lean.
The smaller the I value, the greater the degree of leaning.
However, from now on, when the engine EG is cold, it is better when it is hot.
The fact that the I value is set smaller than that of the engine E
G has a larger leaning coefficient in cold condition than in hot condition.
It is defined.

The switching means 54-4 receives a control signal from a switching control means 57, which will be described later, and
One of -1 to 54-3 is selected. Conditions for selecting each of the I value setting means 54-1 to 54-3 are as follows. (1) Conditions for selecting the I value setting means 54-1 When the engine speed is smaller than a predetermined value (this is called a release speed) _{NL in the} deceleration zone (see zone A in FIG. 6). . When the temperature is not the deceleration zone but is lower than the air-fuel ratio feedback control start water temperature Tw1. In the case of a high load zone instead of a deceleration zone (Fig. 6
Zone D). (2) Conditions deceleration zone for I value setting means 54-2 is selected - rather than down, in an air-fuel ratio feedback control starting water temperature Tw1 above, rather than high-load zone, if the O ₂ sensor is inactive. (3) Conditions for Selecting I Value Setting Means 54-3 When the engine speed is equal to or higher than the release speed _{NL in the} deceleration zone (see zone B in FIG. 6).

K_AFMThe setting means 54-5 is provided with an engine load
Coefficient K according to and engine speed _AFMWhat sets
It is. In addition, engine cooling water temperature Tw, intake air temperature, atmospheric pressure
[Correction coefficient K corresponding to engine cooling
Since it is set according to the water temperature Tw, at low temperatures (at warm-up)
Corrections that are set to be enriched)
Means 55 are provided, and further according to the battery voltage.
Time (invalid time) T to correct driving time
_DIs also provided.
You.

Further, the switching means 52A, 52B, 54-
Switching control means 57 for performing the switching control of No. 4 is provided. Here, the switching means 52 by the switching control means 57
A, 52B, 54-4 switching control will be described. That is, this switching control means 57 is not a deceleration zone, but the air-fuel ratio feedback control start water temperature Tw1 or more.
When the O ₂ sensor is active instead of the high load zone (FIG. 6)
In the zone C), the feedback air-fuel ratio correction coefficient setting means 53 is selected, and if at least one of the above conditions is not satisfied (see zones A, B, and D in FIG. 6), the air-fuel ratio correction coefficient setting is performed. As selecting the means 54,
In addition to controlling the switching means 52A and 52B,
If the condition for selecting the value setting means 54-1 is satisfied, the I value setting means 54-1 is selected. If the condition for selecting the I value setting means 54-2 is satisfied, The I value setting means 54-2 is selected, and the I value setting means 54-2 is selected.
If the condition for selecting No. 3 is satisfied, the switching means 54-4 is controlled so as to select the I value setting means 54-3.

Thus, the fuel injection time T _inj (= T _B × K _AF × K +) determined by the basic drive time T _B , the air-fuel ratio correction coefficient K _AF (2 / P + I or I × K _AFM ), the correction coefficient K, etc.
The fuel is injected at T _D ).
In this way, the above-described ECU 23 determines whether the engine EG has a deceleration operation by detecting the deceleration operation of the engine EG. By setting
It has the function of air-fuel ratio control means for controlling the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber to a leaner side than the stoichiometric air-fuel ratio. set to <br/> Ru function according coefficients warming up state of the engine also becomes to have.

At this time, the I value is set to be smaller when the engine EG is cold than when it is hot (see FIG. 5).
From now on, when the engine EG is colder than when it is hot
Also has a large leaning coefficient and is supplied to the combustion chamber
The air-fuel ratio of the air-fuel mixture is controlled to be leaner than the stoichiometric air-fuel ratio . Further, in a low rotation speed operation state including an idle rotation speed (an operation range lower than the release rotation speed),
= 1.0, so that it has a function of means for prohibiting the setting of the leaning coefficient in this low rotation speed operation state.

Hereinafter, the fuel injection control will be described with reference to a flowchart shown in FIG. First, in step A1, the operation state is input. In step A2, whether the detected Ev is smaller than the deceleration zone upper limit judgment Ev (Ev is volumetric efficiency) having engine load information (see FIG. 6) is determined. Is determined. If it is the deceleration zone, it is determined in step A3 whether the engine speed is equal to or higher than the release speed _NL . If the engine speed is equal to or higher than the release speed N _L , that is, in the case of zone B in FIG. 6, in step A4, a map value (see FIG. 5) is read according to the engine coolant temperature and input to I. Then, thereafter, in step A4-2, a coefficient K _AFM is set according to the engine load and the engine speed, and in step A5,
_Let K _AF = I × K _AFM . As a result, as can be seen from FIG. 5, when the engine is cold, the engine is colder than when the engine is hot.
Considering that the leaning coefficient is set large and consequently the warming-up increase coefficient is set to be large to cope with high load operation at low temperatures, the leaning coefficient is set large as described above , Air-fuel mixture supplied to the chamber
The ratio is controlled to be leaner than the stoichiometric air-fuel ratio ,
In particular, it is possible to reduce the amount of HC emission during low-temperature deceleration,
Also, fuel efficiency can be improved.

In step A3, when the engine speed is lower than the release speed _{NL, that} is, in the case of zone A in FIG. 6, I = 1.0 in step A7, and then in step A4-2, A coefficient K _AFM is set according to the engine load and the engine speed. Further, at step A5, K _AF = I ×
_Let K _AFM = K _AFM . In this manner, leaning is prohibited (stopped) in the low rotation speed operation state including the idle rotation speed, so that the probability of occurrence of stall can be reduced.

If the vehicle is not in the deceleration zone,
In step A6, whether the feedback start water temperature Tw1 or more
It is determined from the feedback start water temperature Tw1
If it is low, in step A7, after I = 1.0,
In step A4-2, the engine load and the engine speed are
Depending on the coefficient K_AFMIs set, and in step A5, K _AF
= I × K_AFM= K_AFMfar. If feedback is open
If the temperature is equal to or higher than the starting water temperature Tw1, the flow proceeds to step A8, where
Judge whether it is a load zone, and if it is a high load zone,
At beam step A7, after setting I = 1.0,
In A4-2, the engine load and the engine speed are related.
Number K_AFMIs set, and in step A5, K_AF= I × K
_AFM= K_AFMfar. If it is not a high load zone,
In step A9, O_TwoDetermines whether the sensor is inactive
If, O_TwoIf the sensor is inactive, step A10
Then, after setting I = 1.05 and enriching, step
In step A4-2, according to the engine load and the engine speed,
Coefficient K_AFMIs set, and in step A5, K_AF= I ×
K_AFM= 1.05 × K_AFMfar.

Further, O_TwoFor sensor activity, the engine
The feedback zone is shown in Zone C in Figure 6
In this case, first in step A11
It is determined whether feedback has just started
You. If so, in step A12, I = 1.0
Then, in step A14, K_AF= P / 2 + I
deep. If not immediately after the start of feedback,
In Step A13, O_TwoComparison result between sensor output and reference value
The I value is set based on _AF= P
/ 2 + I. This allows O_TwoBased on sensor output
Air-fuel ratio feedback control is performed.

[0034] Note that steps A14, after step A5, the setting of the correction coefficient K and dead time T _D is performed (step A15). Also, it has been made suitable also set the basic drive time T _B. Therefore, when the engine operation state is in zone C in FIG. 6 (feedback operation range)
The air-fuel ratio feedback control based on the O ₂ sensor output is performed, and when the engine is in the zone D (high load operation range) in FIG. 6, lean operation is prohibited, and when the O ₂ sensor is inactive, Is enriched,
When the engine operation state is in zone B (deceleration operation area excluding the low rotation number operation area) in FIG. 6, the leaning coefficient is set to be larger when the engine is cold than when the engine is hot .
The air-fuel ratio of the mixture supplied to the combustion chamber is lower than the stoichiometric air-fuel ratio.
Since the control is performed on the lean side, it is possible to reduce the amount of HC emission particularly during low-temperature deceleration, and also to improve fuel efficiency.

The engine operating state is indicated by a zone A in FIG.
When the vehicle is in the (deceleration operation region including the low rotation speed operation region), leaning is prohibited (stopped), so that the probability of occurrence of stall can be reduced. Further, deceleration shock and engine stop (engine stall) in a low engine speed range can be eliminated, so that drivability can be improved.

(B) Description of the Second Embodiment FIG. 7 is a flowchart for explaining the control procedure of the air-fuel ratio control device for an internal combustion engine as a second embodiment of the present invention.
In the second embodiment, when the engine is cold, the I value is set smaller and the leaning coefficient is set larger than when the engine is hot.
The air-fuel ratio of the mixture supplied to the combustion chamber is the stoichiometric air-fuel ratio.
As a means for controlling to a leaner side, the I value is stepwise (2
), And then increase the leaning coefficient stepwise (two steps).
Floor) . In the first embodiment described above, the one in which the leaning coefficient is changed continuously is used.

Therefore, in the second embodiment, the I value setting means 54-3 sets the engine cooling water temperature Tw to the predetermined value Tw.
2 (Tw2s> Tw1) or less, I = 0.9,
If the engine cooling water temperature Tw is higher than a predetermined value Tw2, I =
The other configuration is almost the same as that of the above-described first embodiment except that it is set to 0.95. Hereinafter, the fuel injection control in the second embodiment will be described with reference to the flowchart shown in FIG.

First, in step B1, the operating state is input, and in step B2, it is determined whether or not the temperature is equal to or higher than the feedback start water temperature Tw1. If the temperature is lower than the feedback start water temperature Tw1, I = 1.0 is set in step B3. If the feedback start water temperature is equal to or higher than Tw1, it is determined in step B4 whether or not the vehicle is in the high load zone. If so, in step B3, I =
At 1.0, if the zone is not a high load zone, it is determined in step B5 whether or not the detection Ev is smaller than the deceleration zone upper limit determination Ev having the engine load information. If it is the deceleration zone, it is determined in step B6 whether the engine speed is equal to or higher than the release speed _NL . If the engine speed is equal to or higher than the release speed _NL , it is determined in step B7 whether the engine cooling water temperature Tw is higher than a predetermined value Tw2. If the engine coolant temperature Tw is higher than the predetermined value Tw2, I = 0.95
(Step B8), and when the engine cooling water temperature Tw is equal to or lower than the predetermined value Tw2, I is set to 0.9 (Step B).
9). In this way, when the engine is cold, the leaning coefficient is set larger than when the engine is hot ,
Control the air-fuel ratio of the mixture to be leaner than the stoichiometric air-fuel ratio.
By that is intended for the same reason as the first embodiment described above, in particular it is possible to reduce the emissions of HC at a low temperature reduction, addition of fuel efficiency can also be improved.

If the engine speed is lower than the release speed _NL at step B6, then at step B3,
1.0. Thus, leaning is prohibited (stopped) in the low rotation speed operation state including the idle rotation speed, so that the probability of occurrence of stall can be reduced. If it is not the deceleration zone, it is determined in step B12 whether or not the O ₂ sensor is inactive. If the O ₂ sensor is inactive, I = 1.05 is set in step B13.

Then, these steps B3, B8, B
After setting the I value to a predetermined value in steps 9 and B13,
In step B10, the engine speed and engine speed are
Number K _AFMIs set, and in step B11, K_AF= I × K
_AFMfar. By the way, not in the deceleration zone,_TwoSensor
If it is active, feedback is started in step B14.
It is determined whether it is immediately after. If so,
In step B15, after setting I = 1.0,
In B17, K_AF= P / 2 + I. Also, the feedback
If it is not immediately after the start of the lock,_TwoC
Set the I value based on the comparison result between the sensor output and the reference value.
In step B17, K_AF= P / 2 + I. this
By O_TwoAir-fuel ratio feedback based on sensor output
Control is performed.

[0041] Incidentally, the step B11, after step B17, the setting of the correction coefficient K and dead time T _D is performed (step B18). Also, it has been made suitable also set the basic drive time T _B. Therefore, also in the second embodiment, when the engine operation state is in zone C of FIG. 6 (feedback operation range), the air-fuel ratio feedback control based on the O ₂ sensor output is performed, and
When the engine operation state is in zone D (high load operation range) of FIG. 6, leaning is prohibited, and when the O ₂ sensor is inactive, the engine is enriched while the engine operation state is changed to FIG.
When the engine is in the zone B (deceleration operation region excluding the low rotation speed operation region), the leaning coefficient is set to be larger when the engine is cold than when the engine is hot, and the mixture supplied to the combustion chamber is reduced.
Since the air-fuel ratio of the gas is controlled to be leaner than the stoichiometric air-fuel ratio, it is possible to reduce the amount of HC emissions, especially during low-temperature deceleration, to improve fuel efficiency, and to improve engine operating conditions. FIG.
In the zone A (deceleration operation range including the low rotation speed operation range), leaning is prohibited (stopped), so that the probability of occurrence of stall can be reduced. Furthermore, drivability can be improved because deceleration shock and engine stall in a low engine speed region can be eliminated.

[0042]

As described above in detail, according to the air-fuel ratio control equipment of an internal combustion engine of the present invention, during warm-up of the internal combustion engine basic retardant
Increase the fuel injection amount so that the fuel is increased at lower temperatures
The correction is made using the set warm-up increase coefficient.
When the deceleration operation state of the internal combustion engine is detected by deceleration operation state detection means for detecting the deceleration operation state of the internal combustion engine,
Set the leaning coefficient and correct the basic fuel injection amount
The Rukoto, equipped with air-fuel ratio control means for controlling the air-fuel ratio of the mixture supplied to the combustion chamber in the lean side from the stoichiometric air-fuel ratio, deceleration luck air-fuel ratio control means, the internal combustion engine is in warm-up
When the internal combustion engine is in a cold state,
The leaning engine is operated so that the air-fuel ratio is leaner than in the hot state.
Since the configuration is such that the number is set, the air-fuel ratio setting during the deceleration operation of the internal combustion engine can be optimized,
This will not only reduce fuel consumption, reduce emissions of harmful substances ,
HC emission during low-temperature deceleration can be reduced and fuel efficiency improved
There are advantages that can be done.

[0043]

[0044]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a control system of an air-fuel ratio control device for an internal combustion engine as a first embodiment of the present invention.

FIG. 2 is a hardware block diagram showing an air-fuel ratio control device for an internal combustion engine as a first embodiment of the present invention.

FIG. 3 is an overall configuration diagram of an engine system having the present apparatus.

FIG. 4 is a flowchart illustrating a control procedure according to the first embodiment of the present invention.

FIG. 5 is an operation explanatory view of the first embodiment of the present invention.

FIG. 6 is an operation explanatory view of the first embodiment of the present invention.

FIG. 7 is a flowchart illustrating a control procedure according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Combustion chamber 2 Intake passage 2a Surge tank 2b Bypass passage 3 Exhaust passage 4 Intake valve 5 Exhaust valve 6 Air cleaner 7 Throttle valve 8 Injector 9 Catalytic converter 11 Air flow sensor 12 Intake temperature sensor 13 Atmospheric pressure sensor 14 Throttle sensor 15 Idle switch 17 O ₂ sensor 19 water temperature sensor 20 vehicle speed sensor 26 cranking switch 21 crank angle sensor (engine speed sensor) 22 TDC sensor 23 electronic control unit (ECU) 24 battery 25 battery sensor 26 cranking switch 27 CPU 28, 29 input interface 30 A / D converter 31 ROM 32 RAM 33 Battery backup RAM 34 Injection driver 35 Spark plug 40 Driver 41 ISC valve 42 Wax valve 51 The present driving time determining means 52A, 52B switching means 53 feedback time air-fuel ratio correction coefficient setting means 54 the air-fuel ratio correction coefficient setting means 54-1～54-3 I value setting means 54-4 switching means 54-5 K _AFM setting means 55 corrects Means 56 Dead time correction means 57 Switching control means EG engine

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02D 41/00-41/40

Claims (1)

(57) [Claims] When the internal combustion engine is warmed up, the basic fuel injection amount is reduced.
The warmer temperature is set so that the fuel is increased as the temperature increases.
With added correction using the machine increase coefficient, when the decelerating operation state of the internal <br/> combustion engine is detected by the decelerating state detection means for detecting a decelerating operation state of the internal combustion engine, by setting the lean coefficient By adding a correction to the basic fuel injection amount,
Air-fuel ratio control means for controlling the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber to be leaner than the stoichiometric air-fuel ratio, wherein the air-fuel ratio control means operates in a deceleration operation state when the internal combustion engine is warmed up.
When the internal combustion engine is cold,
The leaning coefficient is set so that the air-fuel ratio is leaner than
Characterized by a constant, the air-fuel ratio control apparatus for an internal combustion engine.