JP2003278583A - Operation control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To more surely restrain catalyst deterioration during fuel cut inhibit operation or fuel cut operation by starting fuel cut operation in the state of surely lowering the catalyst temperature in the course of fuel cut inhibit operation to a designated low temperature region in every internal combustion engine having variation in characteristic. <P>SOLUTION: When a catalyst bed temperature TC exceeds a first temperature determination value T1, fuel cut from the point of time when a throttle opening TA is fully opened is inhibited and intake air is supplied through ISCV. The occurrence of misfire due to rich air-fuel mixture is prevented to promote lowering of the catalyst bed temperature TC. From the point of time when the catalyst bed temperature TC is below a second temperature determination value T2, the intake air supplied through the ISCV is gradually decreased, thereby gradually decreasing generation torque. According to oxygen concentration in exhaust emission detected by an O<SB>2</SB>sensor, the point of time when misfire starts to occur with development into rich air-fuel mixture is detected, and from this point of time, fuel cut is started. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for an internal combustion engine that cuts fuel when decelerating a vehicle, for example.

[0002]

2. Description of the Related Art Conventionally, in an electronically controlled fuel injection control device provided in an internal combustion engine, generally, when the vehicle is decelerating, the throttle is not operated and the engine speed is in a predetermined high speed range. At this time, fuel cut control for temporarily stopping the fuel supply is performed, and unnecessary fuel consumption is reduced.

Further, Japanese Patent Laid-Open No. 8-1 proposed by the applicant of the present application
The fuel cut control device disclosed in Japanese Patent No. 44814 is
When the catalyst temperature of the exhaust gas purifying catalyst device reaches a predetermined high temperature range, fuel cut is prohibited even in the above operating state. Then, by prohibiting the fuel cut, the exhaust system is prevented from becoming a high temperature lean atmosphere with excess oxygen, so that deterioration of the catalyst is not promoted.

Furthermore, Japanese Patent Laid-Open No. 10-
The fuel cut control device disclosed in Japanese Patent No. 2525232 supplies intake air in an amount corresponding to the engine speed through the idle adjust passage (bypass passage) while the fuel cut is prohibited. As a result, the air-fuel mixture is prevented from becoming rich over the combustion limit during the prohibition of fuel cut, preventing the occurrence of misfire, and preventing the catalyst temperature from rising excessively due to unburned fuel.

When the fuel cut inhibition control is performed in this way, the fuel cut is started from the time when the catalyst temperature falls to a predetermined low temperature range, and the fuel consumption during vehicle deceleration is reduced. However, when the supply of intake air through the idle adjustment passage is stopped and the fuel cut is started from the fuel cut prohibition state, the torque generated is drastically reduced, and the vehicle in the deceleration state is impacted. This is because while the fuel cut is prohibited, the torque that does not accelerate the vehicle is generated by the intake air supplied through the idle adjustment passage, while the torque is not generated during the fuel cut.

In order to deal with such a problem, the applicant of the present application gradually reduces the intake air amount supplied through the idle adjuster passage when the prohibition of the fuel cut is released so that the intake air amount is "0". In this situation, we devised a control method that suppresses the sudden decrease in torque by starting the fuel cut when.

That is, by gradually reducing the intake air amount, the air-fuel mixture is gradually made rich, and the occurrence frequency of misfire is gently increased, whereby the torque is gently reduced.

This control method will be described with reference to the time chart of FIG. First, irrespective of the throttle opening TA, the ISC opening of ISCV is adjusted to a basic ISC opening eqcrsb of a size corresponding to the engine speed NE, and the intake air of the supply amount according to the basic ISC opening eqcrsb is adjusted. Is supplied through the idle adjuster passage. This is mainly
When the vehicle is traveling downhill, the mixture is prevented from becoming excessively rich when the accelerator opening TA is slightly opened.
This is to prevent the catalyst bed temperature TC from rising excessively by limiting the frequency of misfires.

Further, when the catalyst bed temperature TC exceeds a predetermined first temperature judgment value T1, the ISC opening is adjusted to a value obtained by adding a new transient ISC opening eqcrstrn to the basic ISC opening eqcrsb. , More intake air is supplied according to the ISC opening. As a result, when the fuel is cut while the catalyst bed temperature TC is in the high temperature range, the mixture is prevented from becoming excessively rich while the fuel cut is prohibited, and the occurrence of misfire is prevented. Prevents an increase in temperature TC.

Then, when the catalyst bed temperature TC decreases with the prohibition of fuel cut and falls below a predetermined second temperature judgment value T2, the transient ISC opening eqcrstrn is gradually decreased to "0" and generated. The fuel cut is started after the torque is gradually reduced.

Here, the basic ISC opening eqcrsb is a range in which the occurrence frequency of misfire does not increase the catalyst bed temperature TC when the throttle opening TA is fully closed so that torque that accelerates the vehicle during deceleration is not generated. Has been set to the minimum amount.
Further, the transient ISC opening eqcrstrn is the basic ISC opening eqcr
When added to sb, it is set to the minimum amount that will prevent misfire.

The rate of decrease of eqcrstrn is set as large as possible within a range in which the decrease of the generated torque does not cause an excessive impact on the vehicle during deceleration by experiments or the like. Then, the fuel cut is started as early as possible to further reduce the fuel consumption.

[0013]

However, there are variations in ISCV and engine, and ISC opening eqcrsb, eqcrs
Even if the set value of trn is the same, the transient ISC opening eqcrstr
The air-fuel ratio varies when n is set to "0".

That is, for a certain set value of the ISC opening eqcrsb, eqcrstrn, since the air-fuel ratio during the decrease of the transient ISC opening eqcrstrn does not become so rich and the frequency of misfire does not increase, the transient ISC opening is not increased. In some cases, the catalyst temperature remains in the low temperature range when eqcrstrn becomes “0”. On the other hand, with respect to the same set value, the air-fuel ratio during the decrease of the transient ISC opening becomes richer and the frequency of misfires increases, so when the transient ISC opening eqcrstrn becomes "0", the catalyst bed temperature In some cases, TC again exceeds the second temperature determination value T2 and rises. In this case, the catalyst temperature rises excessively while the fuel cut is prohibited, and the catalyst is exposed to the high temperature lean atmosphere during the fuel cut.

Therefore, the transient ISC is not excessively enriched during the decrease of the transient ISC opening for all the individuals.
It has been difficult to set the basic ISC opening eqcrstrb and the transient ISC opening eqcrstrn so that the catalyst temperature when the C opening eqcrstrn becomes “0” is surely in the low temperature range.

The present invention has been made to solve the above problems, and its object is to prohibit fuel cut from the time when the throttle operation is stopped when the catalyst temperature is in a predetermined high temperature range. An internal combustion engine that suppresses a sudden decrease in generated torque by supplying intake air to lower the catalyst temperature to a predetermined low temperature range, and then gradually reducing the supply amount of intake air and then starting fuel cut In the operation control device, it is possible to start the fuel cut while the catalyst temperature is reliably lowered to the low temperature range while the fuel cut is prohibited, and more reliably suppress the catalyst deterioration during the fuel cut prohibition and during the fuel cut. An object of the present invention is to provide an operation control device for an internal combustion engine that can perform the operation.

[0017]

[Means for Solving the Problems] Means for solving the above problems, and their actions and effects will be listed. According to the first aspect of the present invention, the fuel is cut when the throttle operation is stopped and the engine speed is in a predetermined high speed range, while the exhaust gas purification provided in the exhaust system of the internal combustion engine is performed. When the catalyst temperature of the catalytic converter is in a predetermined high temperature range, fuel cut is prohibited and intake air is supplied to limit the occurrence of misfire to promote the decrease of the catalyst temperature even in the above operating state, In the operation control device of the internal combustion engine, which gradually reduces the intake air supply amount after the temperature has dropped to a predetermined low temperature range and gradually reduces the generated torque, the intake air supply amount is changed. Based on the detected amount that changes corresponding to the air-fuel ratio of the air-fuel mixture that becomes rich as the temperature gradually decreases, fuel is burned in the range where the occurrence of misfire does not raise the catalyst temperature above the low temperature range. Characterized in that it comprises the execution control means for starting the Tsu bets.

According to the first aspect of the present invention, when the catalyst temperature is in a high temperature range, a high temperature lean atmosphere generated by fuel cut or unburned gas generated by prohibiting fuel cut when intake air is insufficient Acceleration of catalyst deterioration due to is suppressed by proper supply of fuel and intake air while the fuel cut is prohibited, and the decrease of catalyst temperature is promoted. If the supply amount of intake air is gradually decreased after the catalyst temperature has dropped to the low temperature range, misfire occurs due to the enrichment of the air-fuel ratio of the air-fuel mixture, and the occurrence frequency thereof gradually increases. Here, based on the detected amount that changes corresponding to the air-fuel ratio of the air-fuel mixture, the fuel cut is started within the range in which the occurrence of misfire does not raise the catalyst temperature above the low temperature range, so the catalyst temperature changes while the fuel cut is prohibited. The fuel cut is started in a state where the temperature has been lowered to the low temperature range more reliably. The air-fuel ratio of the air-fuel mixture at the time of starting the fuel cut based on the detected amount may be the state immediately before the misfire occurs, or the state where the misfire actually starts.

According to a second aspect of the invention, in the first aspect of the invention, the execution control means corresponds to the air-fuel ratio of the air-fuel mixture that becomes rich as the supply amount of intake air is reduced. And a fuel cut means for starting fuel cut in a range where occurrence of misfire does not raise the catalyst temperature above the low temperature range based on the detected quantity. .

According to the invention of claim 2, claim 1
In addition to the effect of the invention described in (1), the air-fuel ratio of the air-fuel mixture in which the supply amount of the intake air is gradually detected is detected by the detection means that detects the detection amount that changes corresponding to this air-fuel ratio. And
Based on this detected amount, the fuel cut means starts fuel cut.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the detected amount is rich in the air-fuel ratio of the air-fuel mixture accompanying a gradual decrease of the intake air supply amount. It is characterized in that it changes in accordance with the frequency of misfires that increases with the increase in the number of accidents.

According to the invention of claim 3, claim 1
Alternatively, in addition to the effect of the invention described in claim 2, the occurrence of misfire causes the catalyst temperature to be lower than that in the low temperature range based on the detected amount corresponding to the occurrence frequency of misfire that increases according to the enrichment of the air-fuel ratio of the air-fuel mixture. The fuel cut is started in the range where it is not raised.

According to a fourth aspect of the present invention, in the third aspect of the invention, the detecting means detects the oxygen concentration in the exhaust gas, which changes in accordance with the occurrence frequency of misfire, as the detected amount. A sensor or an air-fuel ratio sensor that detects the air-fuel ratio in the exhaust gas as the detection amount.

According to the invention of claim 4, claim 3
In addition to the effect of the invention described in (1), the range where the occurrence of misfire does not raise the catalyst temperature above the low temperature range, based on the oxygen concentration in the exhaust gas corresponding to the occurrence frequency of misfire, or the air-fuel ratio in the exhaust gas as well. The fuel cut is started at.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the opening is provided in the intake passage of the internal combustion engine by a throttle valve that is interlocked with throttle operating means. A throttle passage to be adjusted and an auxiliary intake passage that bypasses the throttle valve are provided, and the opening of the auxiliary intake passage is adjusted by a flow control valve that is electrically controlled. It is supplied through the auxiliary intake passage, and the supply amount is adjusted by the flow rate adjusting valve.

According to the invention of claim 5, claim 1
In addition to the operation of the invention described in any one of claims 4 to 4, the auxiliary intake air is provided during the prohibition of the fuel cut in which the throttle operation by the throttle operation means is stopped and the supply of the intake air through the throttle passage is stopped. The intake air is supplied through the passage, and the supply amount is adjusted by an electrically controlled flow control valve.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in an operation control device for a vehicle engine system will be described below with reference to FIGS.
It will be described with reference to FIG.

As shown in FIG. 1, the vehicle engine system comprises an engine 10 as an internal combustion engine, an engine electronic control unit (hereinafter referred to as ECU) 11 and the like.

The engine 10 is a port injection type four-stroke reciprocating engine, which is provided with a fuel injector (hereinafter abbreviated as injector) 12 and a spark plug 13. An ignition coil 14 having a built-in igniter is attached to the ignition plug 13.

On the intake path to the engine 10, an air cleaner 15, a throttle body 16 as a throttle passage, and a resonator 17 are provided in this order from the upstream side. The throttle body 16 forms a part of an intake passage, and a throttle valve 16a is provided in the intake passage. The throttle valve 16a is connected to an accelerator pedal 18 as a throttle operating means by a wire or the like, and opens / closes in conjunction with the accelerator operation.

The throttle body 16 includes an electrically controlled idle speed control valve (hereinafter referred to as IS) as a flow rate control valve.
Called CV. ) 19 are integrally provided. ISCV
19 has an ISC intake passage 19a as an auxiliary intake passage that bypasses the throttle valve 16a.

On the other hand, a three-way catalyst device (hereinafter abbreviated as catalyst) 20 is provided on the exhaust path from the engine 10. This engine system has an engine 1
Various sensors are provided for detecting vehicle information used for driving control of 0.

The crank position sensor 21 provided in the engine 10 outputs a signal for detecting the crank position of the crankshaft and the crank angular velocity (engine speed). Similarly, the cam position sensor 22 outputs a signal for determining the cylinder. The air flow meter 23 provided on the downstream side of the air cleaner 15 is of a hot wire type and outputs a signal according to the intake air amount. The throttle opening sensor 24 provided near the throttle valve 16a outputs a signal according to the throttle opening.
O as a detection means provided upstream of the catalyst 20
The 2 (oxygen) sensor 25 outputs a signal that changes according to the oxygen concentration (detection amount) in the exhaust gas. The vehicle speed sensor 26 provided on the wheel portion outputs a signal for detecting the vehicle speed.

As shown in FIG. 2, the sensors 21 to 26 are provided.
Is electrically connected to the input side of the ECU 11, and includes an injector 12, an ignition coil 14, and an ISCV 19
Are electrically connected to the same output side. The ECU 11
It is a known device including a microcomputer (not shown), a driving device, and the like. The operation control device of the present embodiment includes an ECU 11, an ISCV 19, a crank position sensor 2
1, an air flow meter 23, a throttle opening sensor 24, and an O2 sensor 25. The execution control means is composed of the ECU 11 and the O 2 sensor 25.

The ECU 11 detects the crank position and the engine speed NE based on the signal input from the crank position sensor 21, and determines the cylinder based on the signal input from the cam position sensor 22. In addition, the air flow meter 23
The intake air amount is detected based on the signal input from the throttle opening sensor 24, and the throttle opening TA is detected based on the signal input from the throttle opening sensor 24. Further, it is determined based on a signal input from the O2 sensor 25 that the oxygen concentration in the exhaust gas has exceeded a predetermined concentration value. In addition, the vehicle speed sensor 26
The vehicle speed is detected based on the signal input from. further,
The ECU 11 estimates the catalyst bed temperature (catalyst temperature) TC of the catalyst 20 from the intake air amount and the engine speed NE.

The ECU 11 executes various controls such as known fuel injection control, ignition timing control, idle speed control, etc. based on the sensor information, and controls the operation of the engine 10 according to the vehicle state at that time.

As fuel injection control, the ECU 11 controls the operation of the injector 12 based on various sensor information such as the intake air amount and the engine speed NE, and controls the fuel injection time, that is, the injection amount according to the operating state. To do. Also,
Air-fuel ratio feedback correction is performed to adjust the air-fuel ratio to the stoichiometric air-fuel ratio based on the oxygen concentration in the exhaust gas.

Further, as the ignition timing control, the ECU 11
Outputs an ignition signal to each ignition coil 14 based on the sensor information such as the intake air amount and the engine speed NE, and controls the ignition timing according to the operating state.

Further, as the idle speed control, the ECU
11 is the throttle opening TA, vehicle speed, engine speed N
The ISCV 19 is controlled to open / close based on sensor information such as E, and the ISC opening is adjusted to control the supply amount of intake air supplied independently of the throttle valve 16a. As the idle speed control, there are a starting auxiliary control for supplying auxiliary air when starting the engine, a feedback control for controlling to a target engine speed, and the like.

Further, as a fuel injection control, the ECU 11 determines that the throttle opening TA is fully closed and the engine speed NE is in a predetermined high speed range.
Fuel cut control is performed to stop the fuel supply. The fuel cut control reduces unnecessary fuel consumption when the vehicle is decelerating.

Further, the ECU 11 inhibits the fuel cut and deteriorates the catalyst supplying the intake air through the ISCV 19 when the operating condition for performing the fuel cut control is satisfied while the catalyst bed temperature TC has reached a predetermined high temperature range. Performs suppression control. The catalyst deterioration suppression control prohibits the fuel cut when the catalyst bed temperature TC reaches a high temperature range and controls the catalyst bed temperature TC.
The fuel cut is started after the catalyst bed temperature TC has dropped to a predetermined low temperature range. It should be noted that the catalyst bed temperature TC reaches a high temperature range in an operating state in which the throttle opening TA is not fully closed when the operating state in which the exhaust gas amount is large and the cooling cannot be sufficiently made, as in the high rotation / high load operation. It's time.

The catalyst deterioration suppression control is executed based on the ISCV control executed on the basis of the ISC opening set by the fuel cut execution control routine executed every predetermined time and the fuel cut prohibition state which is the same. The injection control is performed.

Next, the catalyst deterioration suppression control will be described according to the fuel cut execution control routine shown in the flow charts of FIGS. As shown in the time chart of FIG. 5, the ECU 11 executes the step (hereinafter, abbreviated as “S”) 10 while the vehicle being throttle-controlled is running, and
As the C opening, an ISC opening (hereinafter referred to as a basic ISC opening) eqcrsb preset for the engine speed NE is set. The basic ISC opening eqcrsb
Is set using a map stored in advance. This basic ISC opening eqcrsb is referred to in the ISCV control, and the actual ISC opening is controlled to this basic ISC opening eqcrsb.

The basic ISC opening degree eqcrsb is the frequency of misfires caused by the rich air-fuel mixture when the throttle opening degree TA is fully closed at the engine speed NE at that time. The rising catalyst bed temperature TC is the first
It is set to the minimum value when the temperature judgment value (for example, 800 ° C.) T1 is not exceeded.

When the catalyst bed temperature TC exceeds the first temperature judgment value T1, the ECU 11 executes the basic IS according to S11 to S13.
The ISC opening is set by adding the transient ISC opening eqcrstrn set to the engine speed NE at that time to the C opening eqcrsb. The transient ISC opening eqcrstrn is set using a map stored in advance. This ISC opening (eqcrsb + eqcrstrn) is referred to in the ISCV control, and the actual ISC opening is the ISC opening (eqcrsb + eqcr).
strn).

The transient ISC opening eqcrstrn is the total ISC opening for the engine speed NE and the basic ISC opening eqcrsb. It is set to the minimum value when it does not occur.

Next, in S14 to S17, the ECU 11 fully closes the throttle opening TA and sets the engine speed NE to a predetermined first speed determination value (for example, 1500).
rpm) R1 is exceeded, the fuel cut is prohibited. Then, by the processing of S10 to S13, the basic ISC opening degree eqcrsb and the transient ISC are changed according to the engine speed NE that decreases with the stop of the throttle operation.
Both the opening eqcrstrn and ISC opening are decreased.

Here, as the throttle opening TA is fully closed, the engine speed NE decreases and the engine load also decreases, so that a large amount of high-temperature exhaust gas is not supplied to the catalyst 20. Therefore, the catalyst bed temperature TC gradually decreases.

The ECU 11 uses S11, S14, S15,
By S18 and S19, while the operating state continues,
Even if the catalyst bed temperature TC falls below the first temperature judgment value T1, the first
The fuel cut is prohibited while the temperature is higher than the second temperature determination value (eg, 780 ° C.) T2 which is set lower than the temperature determination value T1.

Next, in S16 and S20, the ECU 11 starts the transitional ISC opening eqcrstrn at that time from the time when the catalyst bed temperature TC falls below the second temperature judgment value T2 in the operating state by a predetermined reduction rate Δtrn. Gradually decrease.
The new transient ISC opening eqcrstrn set here is S
A new ISC opening is set by the processing of S12 and S13, and the actual ISC opening is controlled by the ISCV control.

The rate of decrease Δtrn is set so that the frequency of misfires that accompany the enrichment of the air-fuel mixture gradually increases and the torque that is generated gradually decreases. And
The value is set as large as possible (absolute value) within a range where an excessive impact due to torque fluctuation does not occur in the vehicle during deceleration.

In this way, the transient IS
When the C opening eqcrstrn is gradually decreased, the air-fuel ratio of the air-fuel mixture gradually becomes rich and misfire occurs,
The frequency of misfires increases with the progress of enrichment. At this time, the oxygen concentration in the exhaust gas increases as the misfire frequency increases. That is, the oxygen concentration as the detected amount changes according to the air-fuel ratio of the air-fuel mixture.

When the voltage signal SV output from the O2 sensor 25 falls below the predetermined voltage judgment value S1 during the process of reducing the transient ISC opening eqcrstrn by S21 to S23, the ECU 11 transient ISC. Opening
Set eqcrstrn to “0” and execute fuel cut. The voltage determination value S1 is set to a voltage value when the oxygen concentration in the exhaust gas reaches the oxygen concentration at which misfire begins to occur due to the decrease in intake air. And EC
U11 determines that the misfire has begun to occur based on the voltage signal SV falling below the voltage determination value S1, and executes fuel cut from this point.

The catalyst bed temperature TC is the second temperature judgment value T2.
The basic ISC opening degree eqcrsb gradually becomes smaller according to the engine speed NE even after falling below. Next, the ECU 11
Is a second rotation speed determination value (for example, 1200 rpm) R2 in which the engine rotation speed NE is set lower than the first rotation speed determination value R1 while the fuel cut is executed by the processing of S24 and S25. When it falls below, the fuel cut is ended.

The second rotational speed determination value R2 is set to a value that does not cause an excessive impact on the vehicle during deceleration due to the torque generated when the fuel cut is stopped and the fuel is supplied.

Even if the fuel cut is prohibited, if the operating conditions are not satisfied, S17, S2
6, the catalyst bed temperature TC is set to the second temperature determination value T by S27.
When it is 2 or more, the transient ISC opening eqcrstrn corresponding to the engine speed NE is secured. Similarly, when the catalyst bed temperature TC falls below the second temperature determination value T2,
The transient ISC opening is set to "0".

Therefore, even if the operating condition for performing the fuel cut is not satisfied, if the catalyst bed temperature TC is a high temperature exceeding the second temperature determination value T2, the throttle opening T
Misfire is prevented when A is in the fully closed state or a state close to the fully closed state, and the reduction of the catalyst bed temperature TC is promoted.

According to the catalyst deterioration suppression control described in detail above,
When the throttle opening TA is fully closed when the catalyst bed temperature TC exceeds the first temperature determination value T1, the fuel cut is prohibited and the intake air is supplied through the ISCV 19. Then, while the fuel cut is prohibited, the misfire due to the enrichment of the air-fuel mixture is prevented, and the decrease of the catalyst bed temperature TC is promoted. From the time when the catalyst bed temperature TC decreases and falls below the second temperature determination value T2, the intake air supplied through the ISCV 19 is gradually reduced and the generated torque is gradually reduced. Then, based on the oxygen concentration in the exhaust gas detected by the O2 sensor 25, the time when misfire starts to occur due to the enrichment of the air-fuel mixture is detected, and the fuel cut is started from this time. Therefore, unlike the control that starts the fuel cut when the transient ISC opening eqcrstrn decreases to “0”, the frequency of misfire does not increase during the decrease of intake air,
The catalyst bed temperature TC will not rise again due to the misfire whose occurrence frequency has increased, and will not exceed the second temperature determination value T2 and the first temperature determination value T1.

Next, the effects of this embodiment described above will be listed. (1) For each engine system having characteristic variations in the throttle passage and the ISCV 19, the fuel cut is performed while the catalyst bed temperature TC is more reliably lowered to a low temperature range lower than the second temperature determination value T2 while the fuel cut is prohibited. You can start.

As a result, while the fuel cut is prohibited, the catalyst 20 is prevented from being exposed to the temperature rise due to misfire,
Further, during the fuel cut, it is possible to prevent exposure to the high temperature lean atmosphere, and it is possible to more reliably suppress the catalyst deterioration during the fuel cut inhibition and during the fuel cut.

(2) The throttle valve 16a is opened and closed in conjunction with the accelerator pedal 18, and the ISCV 19 is set to EC.
In the engine system that U11 controls to supply the intake air while the fuel cut is prohibited, the O2 sensor 25 is newly added.
The supply of intake air is terminated based on the signal of. Therefore, it is not necessary to add new parts to the conventional engine system, and it is possible to carry out by simply causing the microcomputer of the ECU 11 to execute the control program of the fuel cut execution control routine for controlling the ISCV 19 based on the signal of the O2 sensor 25. .

(3) In fuel injection control, the O2 sensor 2 provided for performing air-fuel ratio feedback control
The occurrence of misfire was determined from the voltage signal of 5.
Therefore, it is not necessary to provide a new sensor for detecting the occurrence of misfire.

Next, embodiments other than the above-mentioned one embodiment will be listed. In the one embodiment, the transient ISC is performed while the fuel cut is prohibited.
The frequency of misfires when the opening eqcrstrn is decreased is determined based on a signal from an air-fuel ratio sensor provided to detect an air-fuel ratio (detection amount) of exhaust gas.
That is, when misfiring begins to occur with the enrichment of the air-fuel mixture, the air-fuel ratio in the exhaust gas increases, so it is possible to indicate that misfiring has begun based on the fact that the air-fuel ratio exceeds a predetermined judgment value. It is detected, and fuel cut is started from this point. Even with such a configuration, (1) of the above-described embodiment,
Each effect described in (2) can be obtained.

In the one embodiment, the air-fuel ratio of the air-fuel mixture when the transient ISC opening eqcrstrn is decreased while the fuel cut is prohibited is detected by the air-fuel ratio sensor for detecting the air-fuel ratio (detection amount) of the exhaust gas. The configuration is such that the determination is made based on the signal. That is, the state immediately before the misfire occurs due to the enrichment of the air-fuel mixture is detected, and the fuel cut is started from this point. Even with such a configuration, (1) of the above-described embodiment,
Each effect described in (2) can be obtained.

In the above-described embodiment, when the amount of intake air supplied through the ISCV 19 is decreased while the fuel cut is prohibited, the value of the transient ISC opening eqcrstrn is set at the time when misfire starts to occur. The fuel cut may be started in a fixed state.

In the above embodiment, the ISCV 19 I
Separately from the SC intake passage 19a, the throttle valve 16a
An auxiliary intake passage that bypasses the auxiliary intake passage is provided, and the amount of intake air supplied through the auxiliary intake passage is adjusted by an electrically controlled flow control valve.

In the one embodiment, the throttle operation may be detected by the accelerator opening sensor that detects the depression state of the accelerator pedal 18. The present invention may be embodied in an engine system in which the throttle valve has an electronically controlled throttle whose opening is adjusted by an electrically controlled actuator. In this case, the ECU does not fully close the throttle valve when the accelerator pedal is no longer depressed, and the basic IS
The throttle valve may be controlled to open by an opening corresponding to the C opening eqcrsb and the transient ISC opening eqcrstrn.
Then, when the catalyst bed temperature TC falls below the second temperature determination value T2 while the fuel cut is prohibited, the transient ISC opening degree eqcrstrn
The throttle valve is configured to be closed at the opening reduction rate corresponding to the reduction rate of. With such a configuration, the effect described in (1) of the one embodiment can be obtained.

The technical idea understood from each of the above embodiments will be described below. (1) In the invention according to any one of claims 1 to 5, the throttle operation is detected by a throttle opening TA sensor (24) that detects an opening of a throttle valve. Operation control device for internal combustion engine.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an engine system for a vehicle including an operation control device for an internal combustion engine according to an embodiment.

FIG. 2 is a block diagram showing an electrical configuration of an engine system.

FIG. 3 is a flowchart of a fuel cut execution control routine.

FIG. 4 is a flowchart of a fuel cut execution control routine.

FIG. 5 is a time chart during fuel cut control for performing catalyst deterioration suppression control.

FIG. 6 is a conventional time chart.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Gasoline engine as an internal combustion engine, 11 ... Engine electronic control device as fuel cut means which constitutes execution control means, 16 ... Throttle body as throttle passage, 16a ... Throttle valve, 18 ... Accelerator pedal as throttle operating means , 19 ... Idle speed control valve as flow rate control valve, 19a ... ISC intake passage as auxiliary intake passage, 20 ... Three-way catalyst device as catalyst, 25 ... O as detection means constituting execution control means
2 sensor, TA ... Catalyst bed temperature as catalyst temperature.

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Claims (5)

[Claims] 1. A catalyst device for exhaust gas purification provided in an exhaust system of an internal combustion engine, while fuel is cut while the throttle operation is stopped and the engine speed is in a predetermined high speed range. When the catalyst temperature is in a predetermined high temperature range, the fuel cut is prohibited and the intake air is supplied to suppress the occurrence of misfire to promote the decrease of the catalyst temperature even in the above-mentioned operating state, so that the catalyst temperature is kept to the predetermined value. In the operation control device of the internal combustion engine, which gradually reduces the intake air supply amount after the temperature has dropped to the low temperature range and gradually reduces the generated torque, then gradually reduces the intake air supply amount. Based on the detected amount that changes corresponding to the air-fuel ratio of the air-fuel mixture that becomes richer, the fuel cut is opened within the range where the occurrence of misfire does not raise the catalyst temperature above the low temperature range. Operation control device for an internal combustion engine, characterized in that it comprises the execution control means for. 2. The execution control means includes a detection means for detecting a detection amount that changes corresponding to the air-fuel ratio of the air-fuel mixture that becomes rich as the supply amount of intake air is reduced, and the detection amount 2. The operation control device for an internal combustion engine according to claim 1, further comprising fuel cut means for starting fuel cut in a range where occurrence of misfire does not raise catalyst temperature above the low temperature range. 3. The detected amount changes in accordance with the frequency of misfires that increases as the air-fuel ratio of the air-fuel mixture becomes richer as the supply amount of intake air is gradually decreased. The operation control device for an internal combustion engine according to claim 1 or 2, characterized in that. 4. The oxygen sensor for detecting the oxygen concentration in the exhaust gas, which changes according to the occurrence frequency of misfire, as the detected amount, or the air-fuel ratio in the exhaust gas as the detected amount. The operation control device for an internal combustion engine according to claim 3, wherein the operation control device is an air-fuel ratio sensor for detecting. 5. The intake passage of the internal combustion engine is provided with a throttle passage whose opening is adjusted by a throttle valve that interlocks with throttle operating means, and an auxiliary intake passage bypassing the throttle valve. Is an electrically controlled flow control valve for controlling the opening degree, wherein the intake air is supplied through the auxiliary intake passage and the supply amount is adjusted by the flow control valve. The operation control device for an internal combustion engine according to any one of claims 1 to 4.