JPH0979057A - Control device for internal combustion engine - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To enable good early activation of a catalyst while maintaining operability. SOLUTION: During engine cooling (determined in S3), the fuel correction coefficients ktwR, ktw are set so that the air-fuel ratio of a specific cylinder (first cylinder 22) is set to rich and the air-fuel ratios of other cylinders are set to lean.
L is calculated (S4), and the fuel injection amount is made to differ among the cylinders (S5). Further, the correction amounts advtwR, advtwL of the ignition timing are obtained (S4), and the ignition timing for each cylinder is set according to the set air-fuel ratio (S5). Then, in order to reduce the intake air amount of the first cylinder 22 relative to the other cylinders, the cam that drives the intake valve 14 of the first cylinder 22 is switched to the cam 13b, and the opening / closing characteristic of the intake valve 14 of the first cylinder 22 is changed. Different from other cylinders (S6). As a result, the output of the first cylinder 22 is reduced, so that it is possible to suppress the output step (torque step) between the cylinders and promote early activation of the catalyst.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine, and more particularly to an improvement of the control device for activating the exhaust purification catalyst at an early stage.

[0002]

2. Description of the Related Art For example, a three-way catalyst as an exhaust gas purification catalyst used for purifying exhaust gas from an internal combustion engine is generally activated when a temperature exceeds a certain temperature. Therefore, when the engine is cold, the catalyst temperature is low, so the catalyst is not activated, and sufficient exhaust gas purification performance cannot be exhibited until the activation temperature is reached.

By the way, unburned components (HC, CO) are contained in the catalyst.
If oxygen and oxygen are supplied, the oxidation reaction will be promoted, so the temperature of the catalyst will be raised rapidly and activated early, but normally when the engine is cold, in order to ensure operability (engine stability). In addition, since the air-fuel ratio is set to be richer than the theoretical mixing ratio, the concentration of unburned components supplied to the catalyst is high, but since the oxygen concentration is generally low, it is possible to promote early activation of the catalyst. Can not.

Therefore, as a conventional control device for an internal combustion engine, there is, for example, that disclosed in Japanese Patent Laid-Open No. 19627/1990, which, as shown in FIG. 12, shows the fuel injection amount of a specific cylinder when the engine is cold. By reducing and cutting
A high concentration of oxygen is periodically supplied while adding an unburned component to the catalyst to accelerate the oxidation reaction, thereby promoting early activation of the catalyst.

[0005]

However, in the above-described conventional control device, since the air-fuel ratio difference is provided between the cylinders, the air-fuel ratio is set to lean for the cylinder set to rich. There is a fear that the output becomes smaller in the cylinders with different torques and torque fluctuations occur, and the drivability (engine stability) is easily impaired.

Incidentally, as a method for alleviating the torque fluctuation due to the variation of the air-fuel ratio, a method of retarding the ignition timing of the rich cylinder is generally used. Because the cycle fluctuation becomes large,
There is a limit to the air-fuel ratio difference (torque fluctuation) that can be absorbed. Further, in the above conventional device, the larger the air-fuel ratio difference between the cylinders, the greater the effect of catalyst activation promotion obtained. There is a fear that the output difference of will not be fully absorbed.

The present invention has been made in view of such a conventional situation, and in order to promote early activation of the exhaust purification catalyst, the exhaust purification catalyst upstream exhaust air-fuel ratio has a predetermined cycle with respect to a predetermined air-fuel ratio when the engine is cold. Repeat rich lean with
Even if the fuel supply amount between the cylinders is made different, the output difference between the cylinders can be sufficiently suppressed, so that the operability can be maintained and the catalyst can be early activated satisfactorily. An object is to provide a control device. It is also an object of the present invention to further promote early activation of the catalyst, to further suppress torque fluctuation, and to simplify the configuration.

[0008]

Therefore, as shown in FIG. 1, an internal combustion engine control apparatus according to a first aspect of the present invention is an internal combustion engine equipped with an exhaust gas purification catalyst for purifying engine exhaust gas. In the control device, an operating state detecting means for detecting an operating state of the engine, a fuel supply amount setting means for setting a fuel supply amount according to the detected operating state, and an empty cylinder intake mixture when the engine is cold. A cylinder fuel supply amount correction means for correcting the set fuel supply amount between the cylinders so that the fuel ratio has a cylinder set to a rich side and a cylinder set to a lean side with respect to a predetermined air-fuel ratio, A cylinder intake air amount control means for controlling an intake air amount between the cylinders so as to suppress an output difference between the cylinders when the fuel supply amount is corrected by the cylinder fuel supply amount correction means. Composed of.

Then, the air-fuel ratio (fuel supply amount) between the cylinders is made different by the cylinder fuel supply amount correcting means, so that the catalyst upstream exhaust air-fuel ratio is made rich and lean at a predetermined cycle with respect to a predetermined air-fuel ratio. Even when the catalyst is activated early, the cylinder intake air amount is controlled through the cylinder intake air amount control means.
It is possible to satisfactorily suppress the output step (torque step) between the cylinders while sufficiently promoting the early activation of the catalyst. That is, it becomes possible to sufficiently promote the early activation of the catalyst while maintaining good drivability.

According to the second aspect of the present invention, the cylinder intake air amount control means is configured as a means for controlling the intake air amount to a predetermined cylinder by selectively switching the opening / closing characteristics of the intake valve. As a result, it becomes possible to control the intake air amount to the predetermined cylinder with a relatively simple configuration.

According to the third aspect of the present invention, the cylinder intake air amount control means is arranged so that the intake air amount to the cylinder set to the rich side becomes smaller than that to the cylinder set to the lean side. The closing timing of the intake valve of the cylinder set to the rich side is set earlier than that of the cylinder set to the lean side.

According to a fourth aspect of the present invention, the cylinder intake air amount control means is configured so that the intake air amount to the cylinder set to the rich side becomes smaller than that to the cylinder set to the lean side. The opening timing of the intake valve of the cylinder set to the rich side is delayed with respect to the cylinder set to the lean side.

According to a fifth aspect of the present invention, the cylinder intake air amount control means is arranged so that the intake air amount to the cylinder set to the rich side becomes smaller than that to the cylinder set to the lean side. The lift amount of the intake valve of the cylinder set to the rich side is set smaller than that of the cylinder set to the lean side.

Thus, the catalyst upstream exhaust air-fuel ratio can be satisfactorily repeated rich and lean with respect to the predetermined air-fuel ratio in a predetermined cycle, and the catalyst can be activated early.
It is possible to reduce the output of the rich cylinder whose fuel supply amount is increased and corrected so as to approach the output of the lean cylinder, thereby suppressing the output step (torque fluctuation). It should be noted that the intake air amount to the lean side cylinder on the side where the fuel supply amount is set to be small is increased to bring it closer to the output of the rich side cylinder where the fuel supply amount is increased and corrected to suppress the output step. However, if the invention according to claims 3 to 5 is adopted, the exhaust gas temperature can be further increased. This is advantageous in that the early activation effect of the catalyst can be enhanced and the fuel consumption can be reduced.

It should be noted that advancing the closing timing of the intake valve (Claim 4), delaying the opening timing of the intake valve (Claim 5), and reducing the valve opening lift amount of the intake valve. (Claim 6) alone has the effect of sufficiently suppressing the output step difference, but by combining any or all of these, the output step suppression effect can be further enhanced.

According to a sixth aspect of the present invention, the cylinder intake air amount control means controls the intake throttle amount via an intake control valve provided in an intake system to control the intake air amount to a predetermined cylinder. It is configured as a means for controlling. As a result, it becomes possible to control the intake air amount to the predetermined cylinder with a relatively simple configuration.

According to a seventh aspect of the present invention, the cylinder intake air amount control means controls the intake air amount to the rich side cylinder to be smaller than that of the lean side cylinder. The intake throttle amount of the cylinder set to the rich side is set to be larger than that of the cylinder set to the lean side via the intake control valve provided in the intake system.

Thus, the catalyst upstream exhaust air-fuel ratio can be satisfactorily repeatedly rich and lean with respect to the predetermined air-fuel ratio in a predetermined cycle, and the catalyst can be activated early.
It is possible to reduce the output of the rich cylinder whose fuel supply amount is increased and corrected so as to approach the output of the lean cylinder, thereby suppressing the output step (torque fluctuation). It is also possible to increase the intake air amount to the lean cylinder on the side where the fuel supply amount is set to be small so as to bring the fuel supply amount closer to the output of the rich cylinder for which the increase correction is made, thereby suppressing the output step. Although possible (the invention according to claim 6 includes this),
According to the invention of claim 7, the exhaust gas temperature can be further increased with respect to the above, so that the early activation effect of the catalyst can be enhanced and the fuel consumption amount can be reduced. It is advantageous.

According to another aspect of the invention, the intake control valve is provided for each cylinder, and is a swirl control valve which is closed when the fuel supply amount correction means corrects the fuel supply amount. In some cases, the swirl control valve for the cylinder set to the rich side is closed so that the intake air amount to the cylinder set to the rich side becomes smaller than that of the cylinder set to the lean side. The open area of the cylinder is set smaller than the open area of the swirl control valve for the cylinder set to the lean side.

As described above, if the swirl control valve is used as the intake control valve, the output difference between the cylinders can be suppressed, and further, the gas flow inside the cylinder is strengthened to stabilize the combustion. Since it is also possible to exert the effect of increasing the ignition timing, for example, when combined with the invention described in claim 9 described later, it becomes possible to retard the ignition timing to a greater extent and, as a result, to raise the exhaust temperature. Therefore, the early activation of the catalyst can be further promoted.

According to the present invention, when the cylinder fuel supply amount correction means corrects the fuel supply amount and the cylinder intake air amount control means controls the intake air amount to a predetermined cylinder. In addition, an ignition timing retard control means for retarding the basic ignition timing set according to the operating state by a predetermined amount is provided.

Thus, by delaying the ignition timing, the output difference between the cylinders can be suppressed and the exhaust gas temperature can be raised, so that the catalyst activation by the air-fuel ratio control by the cylinder fuel supply amount correction means is performed. Combined with the activating effect, the early activating effect of the catalyst can be further enhanced.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
It will be described with reference to the accompanying drawings. As shown in FIG.
In the embodiment, an air flow meter 2 is provided downstream of the air flow meter 1 provided upstream of the intake passage of the internal combustion engine 21, and the air flow meter 2 detects the intake air flow rate Qa. .

A throttle opening sensor 4 is provided on the throttle valve 3 provided downstream of the air flow meter 2 so that the throttle opening TVO can be detected. These detection signals are information related to the operating state of the engine 21, that is, the detection signal of the cooling water temperature sensor 5 for detecting the engine temperature (cooling water temperature) Tw and the detection of the crank angle sensor 6 for detecting the engine rotation speed Ne. The signal is input to the control unit 7 together with the signal.

The control unit 7 is a microcomputer used for engine control, and includes a CPU, ROM, R
It is configured to include an AM, an A / D converter, an input / output I / F and the like. It should be noted that the control unit 7 functions as the operating state detecting means, the fuel supply amount setting means, the cylinder fuel supply amount correcting means, the cylinder intake air amount controlling means, and the ignition timing retarding controlling means according to the present invention by software. I have it.

The control unit 7 calculates the fuel injection amount according to the operating condition, and distributes the calculation result toward the intake port 10 downstream of the intake manifold 9 branched from the collector 8 for each cylinder. The fuel is transmitted as a drive signal for the injector (fuel injection valve) 11 provided, and the fuel is injected and supplied from the injector 11.

Communication between the intake port 10 and the cylinder 12
The shutoff is performed by the intake valve 1 that is driven to open and close by the intake side cam 13.
4 through the cylinder 12 and the exhaust port 15
The exhaust side cam 16 opens and closes the connection and disconnection of
It is designed to be performed through the exhaust valve 17. Ma
And an exhaust manifold located downstream of the exhaust port 15
O as the air-fuel ratio detecting means is provided in the collecting portion of 18.₂Sensor 1
9 is provided, which allows O in exhaust gas ₂Check the concentration
It is possible to detect the air-fuel ratio of exhaust gas by outputting it. this
The detection result is input to the control unit 7 and the engine
After warming up, the actual air-fuel ratio is determined based on the detection result.
Air-fuel ratio feedback control is performed so that the air-fuel ratio becomes
It is supposed to be. In addition, further downstream of the exhaust passage
Is a three-way catalyst not shown (other exhaust purification catalyst, such as acid
(The catalyst may be a lean catalyst, a lean NOx catalyst, etc.)
It is supposed to be.

The control unit 7 also calculates the ignition timing according to the operating state, and the ignition plug 20 ignites each cylinder based on the calculation result. By the way, in the present embodiment, the internal combustion engine 2
1 will be described as a representative of four cylinders (any number of cylinders may be used as long as there are a plurality of cylinders). Among them, for the first cylinder 22, the air-fuel ratio during engine cooling is higher than that of other cylinders. The air-fuel ratio is set to rich.

The intake side cam 13 is the first cylinder 22.
With a variable valve timing mechanism, and based on a signal from the control unit 7, via the switching valve 23, the cams 13a and 13b having different profiles.
Can be selectively switched for use. The profile of the intake side cam 13 for the other cylinders, that is, the cylinders for which the air-fuel ratio is set to lean when the engine is cold, is the same as that of the cam 13a.

Here, the fuel injection amount setting control, the ignition timing setting control, and the cam (intake valve opening / closing characteristics) selection switching control performed by the control unit 7 in the present embodiment will be described with reference to the flowchart of FIG. In step (indicated as S in the figure. The same applies hereinafter) 1,
Engine rotation speed Ne, intake air flow rate Qa, cooling water temperature Tw,
Read the throttle opening TVO.

In step 2, based on the information read in step 1, the basic fuel injection amount Tp is set in the same manner as in the conventional case.
And the basic ignition advance value ADV are calculated. In step 3,
It is determined whether or not the cooling water temperature Tw is equal to or lower than a predetermined value Twl (Tw ≦ Twl).
Proceed to. In the case of NO, it is determined that the engine 21 has finished warming up, and the routine proceeds to step 7 to perform normal control.

In step 4, the fuel correction coefficient (or quantity) k of the rich cylinder (first cylinder 22 in this embodiment) which is preset and stored in the control unit 7 is stored.
twR, fuel correction coefficient (or amount) ktw for lean cylinders (cylinders other than the first cylinder 22 in this embodiment)
L, the ignition timing correction amount (or coefficient) advtwR of the rich cylinder, and the ignition timing correction amount (or coefficient) advtwL of the lean cylinder are read. Note that kt
wR and ktwL are set based on a map as shown in FIG. 7, for example. Also, advt
wR and advtwL are set based on a map as shown in FIG. 8, for example.

In step 5, the basic fuel injection amount Tp is calculated based on the correction coefficient and the correction amount read in step 4, and the correction amount set based on the operating state (cooling water temperature, rotation speed, load, starting time, etc.). And the basic ignition advance value ADV are corrected, and the final fuel injection amount Ti to be injected into the rich cylinder
Final fuel injection amount Ti to be injected into R and lean cylinders
L, the final ignition timing FADV to ignite the rich cylinder
Final ignition timing FADV to ignite R and lean cylinders
Find L.

As a result of this correction, the characteristics of the air-fuel ratio in the rich cylinder and the lean cylinder become as shown in FIG. 4, for example, and in the rich cylinder, the concentration of the unburned component in the exhaust gas set to the rich side of the theoretical air-fuel ratio is set. On the other hand, in the lean cylinder, the oxygen concentration in the exhaust gas is increased by being set to the lean side of the stoichiometric air-fuel ratio. At this time, the ignition timing is set so as to be retarded to the stable limit of each of the rich cylinder and the lean cylinder, and as a result, the exhaust temperature is raised, and as a result, the ignition timing is controlled by the control of the air-fuel ratio. Therefore, it is possible to further accelerate the early activation of the catalyst.

The difference between the air-fuel ratios of the rich cylinder and the lean cylinder in the time required from cold engine start to catalyst activation is shown in FIG. 5, for example, and the larger the air-fuel ratio difference is, that is, The higher the concentration of unburned components and oxygen supplied, the earlier the catalyst will be activated,
The larger the air-fuel ratio difference, the smaller the output in the lean cylinder, and the larger the output difference with the rich cylinder, and the larger the torque fluctuation.

Therefore, in this embodiment, as described above,
In step 5, when performing control to provide an air-fuel ratio difference between the cylinders, the process proceeds to step 6, and in step 6, the intake side cam 13 of the rich cylinder (corresponding to the first cylinder 22) is set.
As shown in the valve lift curve of FIG. 6, the closing timing of the intake valve can be set earlier than the closing timing of the intake valve of the lean cylinder (cylinder other than the first cylinder 22), and the lift amount can be set small. Cams 13 with different profiles
Select b. It should be noted that the effect of suppressing the torque step is obtained by simply advancing the closing timing of the intake valve or by setting the lift amount to a small value. Therefore, the cam 13b can achieve only one of them. It may be a profile.

As a result, the intake amount in the rich cylinder decreases, the cylinder pressure decreases, and the output decreases.
The output difference from the lean cylinder is reduced, and the torque (rotation) fluctuation can be suppressed. Step 3
If NO is determined, it is assumed that the engine 21 has been warmed up, and the process proceeds to step 7. However, after the output signal of the O ₂ sensor 19 is read in step 7, the air-fuel ratio feedback control is being performed in step 8. If it is during the air-fuel ratio feedback control (YES), the process proceeds to step 9. In step 9, a so-called air-fuel ratio feedback correction coefficient is set by proportional-plus-integral control based on the output signal of the O ₂ sensor 19 so that the actual air-fuel ratio matches the target air-fuel ratio, and the fuel injection is performed by the correction coefficient. The air-fuel ratio feedback control similar to the conventional method for correcting the amount is performed.

When it is determined in step 8 that the air-fuel ratio feedback control is not in progress (NO), the routine proceeds to step 11, where the correction by the air-fuel ratio feedback correction coefficient is not performed and the basic fuel injection amount Tp and various corrections are performed. coefficient (water temperature correction coefficient, learning correction coefficient K _L and the like based on the load) by a, and it calculates the final fuel injection amount Ti, to perform the fuel injection. Note that the ignition timing is set to a value that is set according to the operating state, as in the normal control.

When passing through step 8 and step 9, since the catalyst has already been activated, the catalyst activation accelerating control is not carried out and the normal control is carried out. As the cam for driving the intake valve 14 of No. 22, the cam 13a having the same profile as that of the other cylinders is selected. As described above, according to the present embodiment, in the case where the air-fuel ratio difference is provided between the cylinders to achieve the early activation of the catalyst,
Since the intake air amount is controlled so as to suppress the output step, it is possible to further enhance the effect of suppressing the output step as compared with the conventional device. In addition, since the ignition timing is also retarded to raise the exhaust temperature,
Also by this, the early activation of the catalyst can be further promoted.

In this embodiment, the specific cylinder to be set rich is described as the first cylinder 22, but the present invention is not limited to this and other cylinders may be used, and a desired catalyst activation promoting effect can be obtained. It goes without saying that a plurality of cylinders may be specified cylinders within the range that can be obtained. In this embodiment, the ignition timing retard control is also performed. However, even if only the intake air amount control is performed, there is a sufficient torque fluctuation suppressing effect, and therefore only the intake air amount control is performed. It may be configured.

Further, in the present embodiment, when the control for providing the air-fuel ratio difference between the cylinders (catalyst activation promotion control) is performed, the ignition timing is retarded to the engine stability limit regardless of whether the cylinder is rich or lean. As described above, when it is desired to prioritize the torque fluctuation suppression effect, the retard control may be performed only for the rich cylinder. Further, in the present embodiment, the description has been made so that the intake air amount is controlled in the suppressing direction for the rich cylinder, but conversely to this, the opening / closing characteristics of the intake valve of the lean cylinder are changed and It is also possible to absorb the torque step by making the output of the lean cylinder closer to the output of the rich cylinder by increasing the intake air amount. Next, a second embodiment will be described.

In the second embodiment, the intake air amount is controlled in the same manner as in the first embodiment, but the above control is performed by controlling the opening / closing characteristics of the intake valve in the first embodiment. On the other hand, in the second embodiment, the control of the intake air amount (intake throttle amount) to a specific cylinder is controlled by an intake control valve (for example, a swirl control valve) provided in the intake passage.
It is designed to be performed under the control of.

In the second embodiment, as shown in FIG.
A swirl control valve (swirl control valve) 24 is provided at the inlet of the intake port 10 of each cylinder.
Based on the drive signal from the control unit 7, the actuator 25 is driven according to the operating state. Other configurations are substantially the same as those in the first embodiment, and thus the description thereof will be omitted.

Incidentally, the swirl control valve 24a of the first cylinder 22 which is set rich when the engine is cold is different from the swirl control valve 24b for other cylinders.
The aperture ratio is set small. Here, the fuel injection amount setting control, the ignition timing setting control, and the swirl control valve control performed by the control unit 7 in the second embodiment will be described with reference to the flowchart in FIG. 10.

Steps A1 to A5 in the flowchart of FIG. 10 are similar to steps 1 to 5 of the flowchart of FIG. 3 in the first embodiment, and steps A7 to A9 of the flowchart of FIG. 10 is similar to steps 7 to 9 of the flowchart of FIG.
Since 1 is the same as step 11 in the flowchart of FIG. 3, description thereof will be omitted.

In the second embodiment, when the engine is cold,
When the air-fuel ratio of the specific cylinder (first cylinder 22) is set to rich and the other cylinders are set to lean, the swirl control valve 24 is closed in step A6. The swirl control valve 24 has, for example, a shape as shown in FIG.
The swirl control valve 24a of the cylinder 22) is set to have a smaller opening area than the swirl control valves 24b of the other cylinders. Therefore, the intake throttle is strong and the resistance is large. Is limited, and as a result, the cylinder pressure decreases and the output decreases. Therefore, as in the case of the first embodiment, the output difference between the rich cylinder (first cylinder 22) and the lean cylinder (other cylinders) is reduced, and the torque (rotation) fluctuation can be suppressed low.

In addition, the swirl control valve 24
Has the effect of strengthening the gas flow inside the cylinder 12 and stabilizing the combustion, so that the ignition timing can be retarded to a greater extent than in the first embodiment, and as a result, the exhaust temperature rises. Therefore, the early activation of the catalyst can be further promoted. As described above, according to the present embodiment, in the case where the air-fuel ratio difference is provided between the cylinders to achieve the early activation of the catalyst,
Since the intake air amount is controlled via the swirl control valve 24 so as to suppress the output step, it is possible to further enhance the effect of suppressing the output step as compared with the conventional device. Further, in addition, since the swirl control valve 24 increases the swirl strength to stabilize the combustion, the ignition timing can be further retarded and the exhaust temperature can be increased as compared with the first embodiment. The early activation of the catalyst can be further promoted.

In this embodiment, the swirl is strengthened and the catalyst is activated as early as possible. However, although the activation promoting effect is slightly inferior, the structure may be simplified. In place of the swirl control valve 24 described above, it is possible to provide an intake throttle valve that increases the intake throttle amount only for the rich cylinder, for example.

In the present embodiment, the ignition timing retard control is also performed. However, even if only the intake air amount control is performed, there is a sufficient torque fluctuation suppressing effect, so only the intake air amount control is performed. It may be configured to perform. Also, in the present embodiment, as in the first embodiment, the specific cylinder set to rich is described as the first cylinder 22, but the present invention is not limited to this, and other cylinders may be used, and the desired cylinder may be used. It is needless to say that a plurality of cylinders may be set as the specific cylinders within a range in which the catalyst activation promoting effect of 1 is obtained, and the degree of rich setting and lean setting can be appropriately changed. Further, in the present embodiment, when the control for providing the air-fuel ratio difference between the cylinders (catalyst activation promotion control) is performed, the ignition timing is retarded to the engine stability limit regardless of the rich cylinder or the lean cylinder. However, if it is desired to prioritize the torque fluctuation suppression effect, the retard control may be performed only for the rich cylinder.

It should be noted that the opening / closing characteristics of the intake valve in the first embodiment are selectively switched to control the amount of intake air to the specific cylinder, and the intake control valve in the second embodiment is used to switch to the specific cylinder. It goes without saying that the control of the intake air amount of the above and the above may be combined. As a result, it becomes possible to further improve the output step absorption capability.

[0051]

As described above, according to the control device for an internal combustion engine according to the first aspect, it is possible to sufficiently promote the early activation of the catalyst while maintaining good drivability. According to the second aspect of the present invention, it is possible to control the intake air amount to the predetermined cylinder with a relatively simple configuration. It should be noted that the intake air amount to the lean side cylinder in which the fuel supply amount is set to be small is increased so as to be closer to the output of the rich side cylinder in which the fuel supply amount is increased and corrected so as to suppress the output step. Although it is also possible (the invention according to claim 2 includes this), if the invention according to claims 3 to 5 is adopted, the exhaust temperature can be further increased with respect to the above. Therefore, the early activation effect of the catalyst can be enhanced, and the fuel consumption amount can be reduced.

According to the sixth aspect of the present invention, it is possible to control the intake air amount to the predetermined cylinder with a relatively simple structure. It should be noted that the intake air amount to the lean side cylinder in which the fuel supply amount is set to be small is increased so as to be closer to the output of the rich side cylinder in which the fuel supply amount is increased and corrected so as to suppress the output step. However, if the invention according to claim 7 is adopted, the exhaust gas temperature can be further increased with respect to the above, so that the catalyst can be activated early. It is possible to enhance the fuel conversion effect and reduce the fuel consumption.

When the swirl control valve is used as the intake control valve as in the eighth aspect of the invention, the output difference between the cylinders can be suppressed, and further, the gas inside the cylinder can be suppressed. Since the effect of strengthening the flow and stabilizing the combustion can be exhibited, for example, when combined with the invention described in claim 9 described later, it becomes possible to retard the ignition timing to a larger extent. As a result, the exhaust gas temperature can be raised, so that the early activation of the catalyst can be further promoted.

According to the ninth aspect of the present invention, by retarding the ignition timing, the output level difference between the cylinders can be suppressed and the exhaust gas temperature can be raised. Therefore, the cylinder fuel supply amount correction Combined with the catalyst activation effect by controlling the air-fuel ratio by the means, the early activation effect of the catalyst can be further enhanced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is an overall configuration diagram of a first embodiment of the present invention.

FIG. 3 is a control unit 7 according to the embodiment.
6 is a flowchart for explaining a fuel injection amount setting control, an ignition timing setting control, and a cam (intake valve opening / closing characteristic) selection switching control performed by the control unit.

FIG. 4 is a time chart explaining the characteristics of the air-fuel ratio in the rich cylinder and the lean cylinder in the same embodiment.

FIG. 5 is a time chart showing a difference in time required from cold engine start to catalyst activation with respect to a difference in air-fuel ratio between the rich cylinder and the lean cylinder in the same embodiment.

FIG. 6 is a diagram illustrating a profile of a cam 13b according to the same embodiment.

FIG. 7 is a diagram showing an example of a map for setting ktwR and ktwL in the same embodiment.

FIG. 8: advtwR, advt in the same embodiment
The figure which shows an example of the map for setting wL.

FIG. 9 is an overall configuration diagram of a second embodiment of the present invention.

FIG. 10 is a flowchart for explaining fuel injection amount setting control, ignition timing setting control, and swirl control valve control performed by the control unit 7 in the same embodiment.

FIG. 11 is a diagram illustrating an opening area when the swirl control valve according to the above embodiment is closed.

FIG. 12A is a time chart showing the drive timing of the injection (fuel injection valve) of the conventional device. (B) is a time chart showing an injector drive command of the conventional device. (C) is a time chart showing the O ₂ concentration near the upstream side of the catalyst in the conventional apparatus.

[Explanation of symbols]

2 Air flow meter 3 Throttle valve 4 Throttle opening sensor 5 Water temperature sensor 6 Crank angle sensor 7 Control unit 11 Injector (fuel injection valve) 13 Intake side cam 13a Cam (for normal time) 13b Cam (for engine No. 1 cylinder) 14 Intake valve 19 O ₂ sensor 20 Spark plug 21 Engine 22 1st cylinder 24 swirl control valve 24a 1st cylinder swirl control valve 24b Other cylinder swirl control valve

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02D 33/00 301 F02D 33/00 301B 301Z 41/04 ZAB 9523-3G 41/04 ZAB 301 301J 41 / 34 ZAB 9523-3G 41/34 ZABN 41/36 ZAB 41/36 ZABB F02P 5/15 ZAB F02P 5/15 ZABK

Claims (9)

[Claims] 1. A control device for an internal combustion engine equipped with an exhaust purification catalyst for purifying exhaust gas of an engine, comprising: an operating state detecting means for detecting an operating state of the engine; and a fuel supply amount according to the detected operating state. A fuel supply amount setting means to be set, and, when the engine is cold, the cylinder intake air-fuel mixture has a cylinder set to a rich side and a cylinder set to a lean side with respect to a predetermined air-fuel ratio. Cylinder fuel supply amount correction means for correcting the set fuel supply amount between the cylinders, and when the fuel supply amount is corrected by the cylinder fuel supply amount correction means, to suppress the output difference between the cylinders, A control device for an internal combustion engine, comprising: a cylinder intake air amount control means for controlling the intake air amount between the cylinders. 2. The internal combustion engine according to claim 1, wherein the cylinder intake air amount control means is a means for selectively switching the opening / closing characteristics of the intake valve to control the intake air amount to a predetermined cylinder. Control device. 3. The cylinder intake air amount control means is set to the rich side such that the intake air amount to the cylinder set to the rich side is smaller than that of the cylinder set to the lean side. The control device for the internal combustion engine according to claim 2, wherein the closing timing of the intake valve of the cylinder to be set is advanced with respect to the cylinder set to the lean side. 4. The cylinder intake air amount control means is set to the rich side such that the intake air amount to the cylinder set to the rich side is smaller than that of the cylinder set to the lean side. 4. The control device for an internal combustion engine according to claim 2, wherein the opening timing of the intake valve of each cylinder is delayed with respect to the cylinder set to the lean side. 5. The cylinder intake air amount control means is set to the rich side so that the intake air amount to the cylinder set to the rich side is smaller than that of the cylinder set to the lean side. The control device for the internal combustion engine according to any one of claims 2 to 4, wherein the lift amount of the intake valve of each cylinder is set smaller than that of the cylinder set to the lean side. 6. The cylinder intake air amount control means is means for controlling the intake air amount to a predetermined cylinder by controlling an intake throttle amount via an intake control valve provided in an intake system. The control device for an internal combustion engine according to any one of claims 1 to 5, which is characterized. 7. The cylinder intake air amount control means is provided with an intake control valve so that the intake air amount to the cylinder set to the rich side is smaller than that to the cylinder set to the lean side. 7. The control device for an internal combustion engine according to claim 6, wherein the intake throttle amount of the cylinder set to the rich side is made larger than that of the cylinder set to the lean side. 8. The rich side when the intake control valve is a swirl control valve which is provided for each cylinder and is closed when the fuel supply amount correction means corrects the fuel supply amount. In order to reduce the intake air amount to the cylinder set to the lean side relative to the cylinder set to the lean side, the opening area of the swirl control valve for the cylinder set to the rich side at the time of closing is the lean side. 8. The control device for an internal combustion engine according to claim 6 or 7, wherein the swirl control valve for a cylinder is set to be smaller than the opening area of the closed valve. 9. The cylinder fuel supply amount correcting means corrects the fuel supply amount, and the cylinder intake air amount controlling means controls the intake air amount to a predetermined cylinder, depending on an operating condition. 9. The control device for an internal combustion engine according to claim 1, further comprising ignition timing retard control means for retarding a set basic ignition timing by a predetermined amount.