JP3620179B2 - Control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for an internal combustion engine.
[0002]
[Prior art]
The combustion chamber is stratified so that the air-fuel mixture is unevenly distributed in the vicinity of the spark plug when the engine is under a low load, and the average air-fuel ratio in the combustion chamber is controlled to the first air-fuel ratio. A control device for an internal combustion engine that is formed and that controls the average air-fuel ratio in the combustion chamber to a second air-fuel ratio richer than the first air-fuel ratio is known.
As a control device for such an internal combustion engine, in the technique described in Japanese Patent Application Laid-Open No. 4-362221, when the engine load exceeds a set load and shifts from stratified combustion to homogeneous combustion, the amount of air is decreased to reduce the amount of intake air. Control is performed, and stratified combustion is continued until the intake air amount actually decreases, and after the actual intake air amount is reduced to the desired air amount, it is switched to homogeneous combustion, and the engine load is lower than the set load. Therefore, a method has been proposed in which when the shift from homogeneous combustion to stratified combustion is performed, the air amount is controlled so as to increase the intake air amount and immediately switched to stratified combustion.
[0003]
[Problems to be solved by the invention]
However, in such a control device for an internal combustion engine, an appropriate method is used when the engine load changes relatively slowly and exceeds or falls below the set load. If it exceeds or falls below, it is inappropriate. This is because when the engine load suddenly changes to a high load and exceeds the set load, the required fuel injection amount greatly increases as the engine load increases. In some cases, it may be necessary to control the air amount to increase the intake air amount together with the injection amount. At that time, the intake air amount is delayed due to a delay in the intake system, and the air-fuel ratio can be stratified combustion This is because the air-fuel ratio becomes richer than the normal air-fuel ratio, so that it may be necessary to perform homogeneous combustion immediately. Further, when the engine load suddenly changes to a low load and falls below the set load, the required fuel injection amount greatly decreases as the engine load decreases. This is because the air amount control may be required to reduce the intake air amount together with the injection amount. That is, the conventional control device has a problem in that a combustible air-fuel mixture cannot be formed in accordance with the magnitude of change in engine load, and a desired engine output may not be obtained.
An object of the present invention is to propose a control device for an internal combustion engine that can appropriately switch the formation of an air-fuel mixture according to the magnitude of a change in engine load and obtain a desired engine output.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows.
FIG. 1 is an explanatory view showing a configuration of a control device for an internal combustion engine according to claim 1. Based on the engine rotational speed detected by the rotational speed detecting means 101 and the engine load detected by the engine load detecting means 102, the set air-fuel ratio calculating means 103 calculates the set air-fuel ratio, and the required fuel injection amount calculating means In 104, the required fuel injection amount of the predetermined cylinder is calculated. Then, the supply air amount control means 105 controls the supply air amount based on the required fuel injection amount so that the set air-fuel ratio is obtained. Also, an intake air amount estimating means 106 for estimating the intake air amount of the predetermined cylinder, and an average of the air-fuel mixture formed in the predetermined cylinder based on the estimated intake air amount of the predetermined cylinder and the required fuel injection amount An air-fuel ratio estimating means 107 for estimating the correct air-fuel ratio is provided,In the estimated air-fuel ratioBased on this, the air-fuel mixture forming means 108 for switching between the formation of the stratified gas mixture and the formation of the homogenized gas mixture is provided.
[0005]
AndThe air-fuel mixture forming means 108 has the following configuration.
Means for forming a stratified mixture when the estimated air-fuel ratio of the predetermined cylinder is in a first air-fuel ratio range in which the stratified mixture can be burned in its operating state; and the estimated air-fuel ratio of the predetermined cylinder Means for forming a homogenized mixture when it is in a range of a second air-fuel ratio that allows combustion of the homogenized mixture in its operating state;If the estimated air-fuel ratio of the predetermined cylinder is in the third air-fuel ratio range in which the combustion of both the stratified mixture and the homogenized mixture can be performed in the operating state, the fuel consumption in the operating state Means for forming a mixture with a lower rate;Means for increasing the fuel injection amount to form a stratified mixture when the estimated air-fuel ratio of the predetermined cylinder is leaner than the range of the first air-fuel ratio; and the estimated air-fuel ratio of the predetermined cylinder is a second When the air-fuel ratio is richer than the range, the fuel injection amount is reduced to form a homogenized mixture.
[0006]
Claim 2In the described invention, the means for increasing the fuel injection amount to form a stratified mixture when the estimated air-fuel ratio of the predetermined cylinder is leaner than the first air-fuel ratio range, As means for forming a stratified mixture by increasing the fuel injection amount based on the estimated intake air amount of the predetermined cylinder so that the air-fuel ratio of the engine becomes the leanest air-fuel ratio in the range of the first air-fuel ratio Configured.
[0007]
Claim 3In the described invention, means for increasing the fuel injection amount and forming the stratified mixture when the estimated air-fuel ratio of the predetermined cylinder is leaner than the range of the first air-fuel ratio is as follows. Configured.
[0008]
A stratified mixture is formed by increasing the fuel injection amount based on the estimated intake air amount of the predetermined cylinder so that the air-fuel ratio of the predetermined cylinder becomes the leanest air-fuel ratio in the range of the first air-fuel ratio. And means for canceling the increase in engine output accompanying the increase in the fuel injection amount by retarding at least one of the ignition timing and the fuel injection timing.
[0009]
Claim 4In the described invention, the means for reducing the fuel injection amount and forming the homogenized mixture when the estimated air-fuel ratio of the predetermined cylinder is richer than the range of the second air-fuel ratio, As means for forming a homogenized mixture by reducing the fuel injection amount based on the estimated intake air amount of the predetermined cylinder so that the air-fuel ratio of the engine becomes the richest air-fuel ratio in the range of the second air-fuel ratio Configured.
[0010]
[Action]
In the first aspect of the invention, the required fuel injection amount is calculated based on the rotational speed and the engine load, and the required fuel is set so that the set air-fuel ratio is calculated based on the rotational speed and the engine load. The supply air amount is controlled based on the injection amount. Then, the intake air amount of the predetermined cylinder is estimated, and the estimated intake air amount and the required fuel injection amountBased on theSince the stratified mixture and the homogenized mixture are switched based on the estimated air-fuel ratio of the mixture to be formed, it is possible to appropriately switch the mixture formation and obtain the desired engine output.
[0011]
AndWhen the estimated air-fuel ratio of the predetermined cylinder is in the first air-fuel ratio range in which the stratified mixture can be burned in the operating state, a stratified mixture is formed, and the estimated air-fuel ratio of the predetermined cylinder is in the operating state. Is in the range of the second air-fuel ratio in which the homogenized mixture can be combusted, the homogenized mixture is formed, and the estimated air-fuel ratio of the predetermined cylinder is homogenized with the stratified mixture in its operating state. When the air-fuel ratio is within the range of the third air-fuel ratio in which both air-fuel mixtures can be combusted, the air-fuel mixture having the smaller fuel consumption rate is formed, and the estimated air-fuel ratio of the predetermined cylinder is When the air-fuel ratio is leaner than the range, the fuel injection amount is increased to form a stratified mixture, and when the estimated air-fuel ratio of the predetermined cylinder is richer than the second air-fuel ratio range, the fuel is injected. The engine load is reduced because the homogenized mixture is formed by reducing the injection amount. Depending on the magnitude of the change, it is possible to switch the appropriate mixture formation in view of fuel consumption rate.
[0012]
Claim 2In the described invention, when the estimated air-fuel ratio of the air-fuel mixture formed by the estimated intake air amount of the predetermined cylinder and the required fuel injection amount is leaner than the range of the first air-fuel ratio, the air-fuel ratio is Since the stratified mixture is formed by increasing the fuel injection amount so as to achieve the leanest air-fuel ratio in the first air-fuel ratio range, the output is close to the desired engine output within a range where stable combustion can be ensured. Can be obtained.
[0013]
Claim 3In the described invention, when the estimated air-fuel ratio of the air-fuel mixture formed by the estimated intake air amount of the predetermined cylinder and the required fuel injection amount is leaner than the range of the first air-fuel ratio, the air-fuel ratio is The fuel injection amount is increased to form the stratified mixture so that the leanest air-fuel ratio in the first air-fuel ratio range is formed, and the increase in engine output accompanying the increase in the fuel injection amount is increased by the ignition timing or the fuel Since it is canceled by retarding at least one of the firing timing, it is possible to obtain an output closer to the desired engine output within a range where stable combustion can be ensured.
[0014]
Claim 4In the described invention, when the estimated air-fuel ratio of the air-fuel mixture formed by the estimated intake air amount of the predetermined cylinder and the required fuel injection amount is richer than the range of the second air-fuel ratio, the air-fuel ratio is Decrease the fuel injection amount so that it becomes the richest air-fuel ratio in the second air-fuel ratio range.HomogenizationSince the air-fuel mixture is formed, it is possible to obtain an output close to a desired engine output as long as stable combustion can be ensured.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 2 is an explanatory diagram showing the configuration of a direct injection type internal combustion engine that employs an embodiment of the present invention. An air flow sensor 3 measures the air flow rate in the intake pipe 2. An auxiliary air passage 4 bypasses the throttle valve 6 and supplies air to the engine 1. Reference numeral 5 denotes an auxiliary air control valve that adjusts the air flow rate of the auxiliary air passage 4, and uses a step motor or the like as an actuator, and is driven by a drive signal from a control circuit ECU to be described later. A throttle actuator 7 drives the throttle valve 6 with a DC motor or the like, and is driven by a drive signal from the control circuit ECU. In the present embodiment, the supply air amount to the engine 1 is adjusted by the throttle actuator 7 and the auxiliary air control valve 5, but the supply air amount is adjusted only by the throttle actuator 7 without providing the auxiliary air passage 4. Alternatively, the supply air amount may be adjusted only by the auxiliary air control valve 5 without providing the throttle actuator 7. 8 is a spark plug and 9 is an injector, which is driven by a drive signal from the control circuit ECU. Reference numeral 10 denotes an air-fuel ratio sensor. There is a crank angle sensor as a sensor (not shown). The crank angle sensor is directly or indirectly connected to the crankshaft or the camshaft interlocked with the crankshaft, and calculates the crank position (crank angle) and the rotation speed based on the crank position. In addition, there are a sensor that measures the engine coolant temperature, a sensor that measures the intake air temperature, a sensor that measures the accelerator opening, a sensor that measures the speed of the vehicle, and the like.
[0016]
FIG. 3 is an explanatory diagram showing the configuration of the control circuit ECU centered on the microcomputer, which performs input / output of information with the outside and various calculations. The CPU executes computations, and the ROM stores a control program and various data described later. The RAM temporarily stores information during program execution. The I / O interface inputs information from an external sensor or the like and outputs a signal for driving an external actuator.
[0017]
Hereinafter, the control method according to the embodiment of the present invention will be described mainly with reference to flowcharts of programs executed by the microcomputer.FIG.Based on
FIG. 4 is a general flowchart of the embodiment of the present invention. The engine speed is detected at 401, the engine load is detected at 402, and the set air-fuel ratio is calculated at 403. In 404, the required fuel injection amount of the predetermined cylinder is calculated, and in 405, the supply air amount is controlled. In step 406, the intake air amount of the predetermined cylinder is estimated. In step 407, the air-fuel ratio of the predetermined cylinder is estimated. In step 408, an air-fuel mixture is formed in the predetermined cylinder.
[0018]
FIG. 5 is a flowchart showing an embodiment of the process in step 402 for calculating the engine load in FIG. At 501, the accelerator opening APS is detected based on the output of the accelerator opening sensor (not shown), and at 502, the rotational speed NE is read. Then, at 503, the target engine torque tTRQ is determined by referring to the map 1 based on the accelerator opening APS and the rotational speed NE.CalculationTo do. Here, the value of the map 1 is determined in advance and stored in the ROM. However, the target engine torque tTRQ may be calculated using a mathematical formula without using the map.
[0019]
FIG. 6 is a flowchart showing an embodiment of the process in step 403 for calculating the set air-fuel ratio in FIG. The target engine torque tTRQ is read at 601 and the rotational speed NE is read at 602. Then, at 603, the set air-fuel ratio sAF is calculated with reference to the map 2 based on the target engine torque tTRQ and the rotational speed NE. Here, the value of the map 2 is determined in advance and stored in the ROM. However, the set air-fuel ratio may be calculated using a mathematical formula without using the map.
[0020]
FIG. 7 is a flowchart showing an embodiment of the process in step 404 for calculating the required fuel injection amount in FIG. The target engine torque tTRQ is read in 701, the rotational speed NE is read in 702, and the required fuel injection amount bQF is calculated with reference to the map 3 based on the target engine torque tTRQ and the rotational speed NE in 703. Here, the value of the map 3 is determined in advance and stored in the ROM. However, the required fuel injection amount bQF may be calculated using a mathematical formula without using the map. In addition, the calculation of the required fuel injection amount may include an operation for correcting the magnitude of the pumping loss due to the difference in the air-fuel ratio.
[0021]
FIG. 8 shows an embodiment of the process in step 405 for controlling the supply air amount in FIG.flowchartIt is. In 801, the required fuel injection amount bQF is read. In 802, the set air-fuel ratio sAF is read. In 803, the target intake air amount tQA of the predetermined cylinder is calculated as tQA = bQF × sAF. Then, at 804, the rotational speed NE is read, and at 805, the throttle opening TVO is calculated based on the target intake air amount tQA and the rotational speed NE. Here, a method of calculating the intake air amount based on the rotational speed and the throttle opening is known, and the throttle opening TVO is calculated by performing an inverse operation of this method. Further, the throttle opening TVO may be calculated using another method.
[0022]
FIG. 9 is a flowchart showing an embodiment of the process in step 406 for estimating the intake air amount in FIG. In 901, the rotational speed NE is read. In 902, the output AFSOUT of the airflow sensor 3 is read. In 903, the throttle opening sensor output TVOSOUT is read. At 904, the estimated intake air amount eQA is calculated in consideration of the dynamics of the intake system based on the rotational speed NE, the output AFSOUT of the airflow sensor 3, and the throttle opening sensor output TVOSOUT.
[0023]
FIG. 10 is a flowchart showing an embodiment of the processing in step 407 for estimating the air-fuel ratio in FIG. In 1001, the required fuel injection amount bQF is read. In 1002, the estimated intake air amount eQA is read. In 1003, the estimated air-fuel ratio eAF is calculated as eAF = eQA ÷ bQF.
[0024]
FIG. 11 shows the implementation of the process in step 408 of forming the air-fuel mixture in FIG.FormFlow chart shownIt is.
[0025]
Now, the target engine torque has changed and the set air-fuel ratio has changed from AF1 in the air-fuel ratio range in which the stratified mixture can be combusted to AF2 in the air-fuel ratio range in which the homogenized mixture can be combusted. The change of air-fuel ratio in caseFIG.When the set air-fuel ratio is changed from AF2 in the air-fuel ratio range in which the homogenized mixture can be combusted to AF1 in the air-fuel ratio range in which the stratified mixture can be combusted. The change of air-fuel ratio ofFIG.As shown in FIG. 1, the air-fuel ratio transition method differs depending on the magnitude of the change in the target engine torque tTRQ. The air-fuel mixture formation method is switched as follows based on the air-fuel ratio transition. Air-fuel ratio range in which both stratified and homogenized mixtures can be combustedIn the range in the vicinity of AFCHG in FIG. 12, an air-fuel mixture having a smaller fuel consumption rate is formed in the operating state.
[0026]
2201When the estimated air-fuel ratio eAF is leaner than AF1MAX,2202The fuel injection amount is increased from the required fuel injection amount bQF by QF = eQA ÷ AF1MAX so that the air-fuel ratio becomes AF1MAX. And2203In this case, the fuel injection amount increase ΔQF is calculated as ΔQF = QF−bQF,2204Read the rotational speed NE at2205Referring to the map 4 based on ΔQF and NE, the ignition side retard correction amount is calculated,2206A stratified mixture is formed in Here, the value of the map 4 is determined in advance and stored in the ROM, but the correction amount of the ignition timing may be performed using a mathematical formula without using the map. In this way, when the estimated air-fuel ratio eAF is leaner than the leanest air-fuel ratio AF1MAX capable of burning the stratified mixture, the fuel injection amount is increased so that the air-fuel ratio becomes AF1MAX, and the ignition timing is increased. Is corrected to the retard side to offset the increase in engine output due to the increase in fuel injection amount. Further, the fuel injection timing may be corrected to the retard side.
[0027]
2207The estimated air-fuel ratio eAF is richer than the leanest air-fuel ratio AF1MAX capable of burning the stratified mixture, and leaner than the leanest air-fuel ratio AF2MAX capable of burning the homogenized mixture In 2208, the fuel injection amount QF is set as the required fuel injection amount bQF, and in 2206, a stratified mixture is formed.
[0028]
In 2209, when the estimated air-fuel ratio eAF is richer than the leanest air-fuel ratio AF2MAX capable of combustion of the homogenized mixture, and leaner than the richest air-fuel ratio AF1MIN capable of combustion of the stratified mixture(When AF2MAX>eAF> AF1MIN)In other words, when the air-fuel ratio is within the range where combustion of both the stratified mixture and the homogenized mixture is possible(Range around AFCHG in FIG. 12)In 2210, the fuel injection amount QF is set as the required fuel injection amount bQF, the rotational speed NE is read in 2211, the target engine torque tTRQ is read in 2212, and the map 5 is referenced in 2213. Choose the gas mixture formation method with the smaller rate. Here, the map 5 stores in advance the characteristics obtained by experiments or the like in the ROM.
[0029]
In 2214, when the estimated air-fuel ratio eAF is richer than the richest air-fuel ratio AF1MIN capable of burning the stratified mixture, and leaner than the richest air-fuel ratio AF2MIN capable of burning the homogenized mixture The fuel injection amount QF is set as the required fuel injection amount bQF at 2215, and the homogenized mixture is formed at 2216.
[0030]
If the estimated air-fuel ratio eAF is richer than the richest air-fuel ratio AF2MIN in which the homogenized mixture can be combusted in 2217, the fuel injection amount QF is calculated in 2218 as QF = eQA ÷ AF2MIN, and the required fuel injection amount At 2216, the homogenized mixture is formed by reducing the amount from bQF.
[0031]
By switching the air-fuel mixture formation method as described above, the air-fuel ratio is within the air-fuel ratio range in which the stratified air-fuel mixture can be combusted from the set air-fuel ratio AF2 in the air-fuel ratio range in which the homogenized air-fuel mixture is combustible. In the case where the change in the target engine torque is very large as shown in FIG. (3) When the estimated air / fuel ratio eAF is leaner than AF1MAX, the ignition timing is retarded as shown in FIG. 20 (d), so that the target engine torque as shown in FIG. 20 (e) is obtained. Is output.
[0032]
In addition, by switching the air-fuel mixture formation method, the air-fuel ratio within the air-fuel ratio range in which the homogenized air-fuel mixture can be combusted from the set air-fuel ratio AF1 in the air-fuel ratio range in which the stratified air-fuel mixture can be combusted. When the air-fuel ratio is changed to a certain set air-fuel ratio AF2, in the case where the change in the target engine torque is relatively small as shown in FIG. (1) Therefore, the throttle opening, the fuel injection amount, and the engine torque are as shown in FIGS. 13 (b) to 13 (d).
[0033]
In the case where the change in the target engine torque is relatively large as shown in FIG. (2) Therefore, the throttle opening, the fuel injection amount, and the engine torque are as shown in FIGS. 14 (b) to 14 (d).
[0034]
In the case where the change of the target engine torque is very large as shown in FIG. (3) Thus, the throttle opening, the fuel injection amount, and the engine torque are as shown in FIGS. 15 (b) to 15 (d).
[0035]
When the air-fuel ratio AF2 in the air-fuel ratio range in which the homogenized mixture can be combusted is changed to the air-fuel ratio AF1 in the air-fuel ratio in which the stratified air-fuel mixture can be combusted. 16), when the change in the target engine torque is relatively small, (1) Thus, the throttle opening, the fuel injection amount, and the engine torque are as shown in FIGS. 17 (b) to 17 (d).
[0036]
In the case where the change of the target engine torque is relatively large as shown in FIG. (2) Therefore, the throttle opening, the fuel injection amount, and the engine torque are as shown in FIGS. 18 (b) to 18 (d).
[0037]
In the case where the change of the target engine torque is very large as shown in FIG. (3) Since the air-fuel ratio changes as shown in FIG. 19, the throttle opening, the fuel injection amount, and the engine torque are as shown in FIGS. 19 (b) to 19 (d).
[0038]
The embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. Are included in the present invention.
[0039]
【The invention's effect】
According to the first aspect of the present invention, stratified aeration is formed in the operating region when the engine is under a low load, and the air-fuel ratio is controlled to a predetermined set air-fuel ratio. In an internal combustion engine in which a fuel-air mixture is formed and the air-fuel ratio is controlled to a predetermined set air-fuel ratio, when the operating conditions change, an appropriate air-fuel mixture formation according to the magnitude of the change in engine load Switching is possible, and a desired engine output can be obtained. In particular, when the change in the engine load is relatively large, a rapid response of the engine output can be realized.
[0040]
AndWhen the operating conditions change, it is possible to appropriately switch the mixture formation according to the magnitude of the change in engine load.
[0041]
further,When the operating conditions change, it is possible to appropriately switch the mixture formation in consideration of the fuel consumption rate in accordance with the magnitude of the change in engine load.
[0042]
Claim 2In the described invention, in a situation where the engine load is rapidly decreased and a desired engine output cannot be generated, an output close to the desired engine output can be obtained within a range in which stable combustion can be secured.
[0043]
Claim 3In the described invention, in a situation where the desired engine output cannot be generated due to a sudden decrease in the engine load, retarding at least one of the ignition timing and the fuel injection timing is within a range where stable combustion can be ensured. An output closer to the desired engine output can be obtained.
[0044]
Claim 4In the described invention, in a situation where the engine load increases rapidly and a desired engine output cannot be generated, an output close to the desired engine output can be obtained within a range where stable combustion can be secured.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of a control device for an internal combustion engine according to claim 1;
FIG. 2 is an explanatory diagram showing the configuration of a direct injection type internal combustion engine that employs an embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a configuration of a control circuit ECU centering on a microcomputer.
FIG. 4 is a flowchart for explaining control of the embodiment of the present invention.
FIG. 5 is a flowchart showing an embodiment of processing in step 402 for calculating engine load in FIG. 4;
FIG. 6 is a flowchart showing an embodiment of a process in step 403 for calculating a set air-fuel ratio in FIG.
FIG. 7 is a flowchart showing an embodiment of processing in step 404 for calculating a required fuel injection amount in FIG. 4;
FIG. 8 shows an embodiment of processing in step 405 for controlling the amount of supplied air in FIG.flowchartIt is.
FIG. 9 is a flowchart showing an embodiment of a process in step 406 for estimating the intake air amount in FIG. 4;
FIG. 10 is a flowchart showing an embodiment of processing in step 407 for estimating the air-fuel ratio in FIG. 4;
FIG. 11In FIG. 4, the execution of the process in step 408 of forming the mixture is performed.FormIt is a flowchart to show.
FIG.FIG. 6 shows the transition of the air-fuel ratio when the air-fuel ratio is changed from the set air-fuel ratio AF1 in the range where the stratified mixture can be combusted to the set air-fuel ratio AF2 in the range where the homogenized mixture can be burned. It is explanatory drawing.
FIG. 13Target engine torque and throttle opening when the set air-fuel ratio AF1 in the range of the air-fuel ratio in which the stratified mixture can be combusted is changed to the set air-fuel ratio AF2 in the range of the air-fuel ratio in which the homogenized mixture can be combusted. It is explanatory drawing which shows a degree, a fuel injection amount, and an engine torque.
FIG. 14Target engine torque and throttle opening when the set air-fuel ratio AF1 in the range of the air-fuel ratio in which the stratified mixture can be combusted is changed to the set air-fuel ratio AF2 in the range of the air-fuel ratio in which the homogenized mixture can be combusted. It is explanatory drawing which shows a degree, a fuel injection amount, and an engine torque.
FIG. 15Target engine torque and throttle opening when the set air-fuel ratio AF1 in the range of the air-fuel ratio in which the stratified mixture can be combusted is changed to the set air-fuel ratio AF2 in the range of the air-fuel ratio in which the homogenized mixture can be combusted. It is explanatory drawing which shows a degree, a fuel injection amount, and an engine torque.
FIG. 16FIG. 9 shows the transition of the air-fuel ratio when the air-fuel ratio changes from the set air-fuel ratio AF2 in the range of the air-fuel ratio in which the homogenized mixture can be combusted to the set air-fuel ratio AF1 in the range of the air-fuel ratio in which the stratified mixture can burn It is explanatory drawing.
FIG. 17Target engine torque and throttle opening when the set air-fuel ratio AF2 in the range of the air-fuel ratio in which the homogenized mixture can be combusted is changed to the set air-fuel ratio AF1 in the range of the air-fuel ratio in which the stratified mixture can be combusted. It is explanatory drawing which shows a degree, a fuel injection amount, and an engine torque.
FIG. 18Target engine torque and throttle opening when the set air-fuel ratio AF2 in the range of the air-fuel ratio in which the homogenized mixture can be combusted is changed to the set air-fuel ratio AF1 in the range of the air-fuel ratio in which the stratified mixture can be combusted. It is explanatory drawing which shows a degree, a fuel injection amount, and an engine torque.
FIG. 19Target engine torque and throttle opening when the set air-fuel ratio AF2 in the range of the air-fuel ratio in which the homogenized mixture can be combusted is changed to the set air-fuel ratio AF1 in the range of the air-fuel ratio in which the stratified mixture can be combusted. It is explanatory drawing which shows a degree, a fuel injection amount, and an engine torque.
FIG. 20Target engine torque and throttle opening when the set air-fuel ratio AF2 in the range of the air-fuel ratio in which the homogenized mixture can be combusted is changed to the set air-fuel ratio AF1 in the range of the air-fuel ratio in which the stratified mixture can be combusted. It is explanatory drawing which shows a degree, fuel injection amount, ignition timing correction amount, and engine torque.
[Explanation of symbols]
1 organization
2 Intake pipe
3 Air flow sensor
4 Auxiliary air passage
5 Auxiliary air control valve
6 Throttle valve
7 Throttle actuator
8 Spark plug
9 Injector
10 Air-fuel ratio sensor

Claims (4)

A rotational speed detecting means for detecting the rotational speed of the engine;
Engine load detecting means for detecting engine load;
A required fuel injection amount calculating means for calculating a required fuel injection amount of a predetermined cylinder based on the engine load and the rotational speed;
A set air-fuel ratio calculating means for calculating a set air-fuel ratio based on the engine load and the rotational speed;
Supply air amount control means for controlling the supply air amount based on the required fuel injection amount and the set air-fuel ratio;
Intake air amount estimating means for estimating the intake air amount of the predetermined cylinder;
Air-fuel ratio estimating means for estimating an average air-fuel ratio of the air-fuel mixture formed in the predetermined cylinder based on the required fuel injection amount and the estimated intake air amount;
Air-fuel mixture forming means for switching between formation of a stratified gas mixture and formation of a homogenized gas mixture in the predetermined cylinder based on the estimated air-fuel ratio ,
The air-fuel mixture forming means includes
Means for forming a stratified mixture when the estimated air / fuel ratio is in a first air / fuel ratio range in which the stratified mixture can burn in its operating state;
Means for forming a homogenized mixture when the estimated air-fuel ratio is in a range of a second air-fuel ratio that allows combustion of the homogenized mixture in its operating state;
When the estimated air-fuel ratio is in the third air-fuel ratio range in which the mixture of both the stratified mixture and the homogenized mixture can be combusted in the operating state, the fuel consumption rate in the operating state Means for forming the smaller mixture,
Means for increasing the fuel injection amount to form a stratified mixture when the estimated air-fuel ratio is leaner than the range of the first air-fuel ratio;
Means for reducing the fuel injection amount to form a homogenized mixture when the estimated air-fuel ratio is richer than the range of the second air-fuel ratio;
An internal combustion engine control apparatus comprising: The means for increasing the fuel injection amount to form a stratified mixture when the estimated air-fuel ratio is leaner than the first air-fuel ratio range,
The stratified mixture is formed by increasing the fuel injection amount so as to achieve the leanest air-fuel ratio in the first air-fuel ratio range based on the estimated intake air amount. The control apparatus for an internal combustion engine according to claim 1 . The means for increasing the fuel injection amount to form a stratified mixture when the estimated air-fuel ratio is leaner than the first air-fuel ratio range,
Means for increasing the fuel injection amount to form a stratified mixture based on the estimated intake air amount so as to achieve the leanest air-fuel ratio in the first air-fuel ratio range;
Means for canceling an increase in engine output accompanying an increase in the fuel injection amount by retarding at least one of an ignition timing and a fuel injection timing;
The control apparatus for an internal combustion engine according to claim 1, comprising: Means for reducing the fuel injection amount to form a homogenized mixture when the estimated air-fuel ratio is richer than the range of the second air-fuel ratio;
Means for reducing the fuel injection amount to form a homogenized mixture based on the estimated intake air amount so as to achieve the richest air-fuel ratio in the range of the second air-fuel ratio;
The control device for an internal combustion engine according to any one of claims 1 to 3, wherein the control device is an internal combustion engine.

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