JP3233031B2 - In-cylinder injection spark ignition internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct injection type spark ignition type internal combustion engine, and more particularly to a direct injection type spark ignition type internal combustion engine capable of injecting fuel in a compression stroke and an intake stroke.

[0002]

2. Related Background Art In recent years, in a spark ignition type internal combustion engine mounted on a vehicle, fuel is directly supplied to a combustion chamber in place of a conventional intake pipe injection type in order to reduce harmful exhaust gas components and improve fuel efficiency. Various direct injection gasoline engines have been proposed. In a cylinder injection type gasoline engine, for example, by injecting fuel from a fuel injection valve into a cavity provided at the top of the piston, an air-fuel mixture having an air-fuel ratio close to the stoichiometric air-fuel ratio is generated around the ignition plug at the time of ignition Let me. This makes it possible to ignite even at a lean air-fuel ratio as a whole, thereby reducing CO and HC emissions and greatly improving fuel efficiency during idling and running under low load.

In such a gasoline engine,
The compression stroke injection mode (late injection mode) and the intake stroke injection mode (first injection mode) are switched according to the operating state of the engine, that is, the engine load.
As a result, during low-load operation, fuel can be injected during the compression stroke to form an air-fuel mixture having an air-fuel ratio close to the stoichiometric air-fuel ratio around the ignition plug or in the cavity. Good ignition can be realized even at a fuel ratio. On the other hand, during medium-high load operation, fuel can be injected during the intake stroke to form a mixture having a uniform air-fuel ratio in the combustion chamber, and thus, like the intake pipe injection type,
By burning a large amount of fuel, it is possible to secure the required output during acceleration or high-speed running.

[0004]

However, in such a direct injection type gasoline engine, setting of fuel injection timing, ignition timing, and the like becomes a problem. Therefore, in such a direct injection type gasoline engine, attention is paid to the fact that the throttle opening in the compression stroke injection mode has a high correlation with the engine load, and is usually calculated from the engine speed and the throttle opening. Target average effective pressure (load correlation value) Pe
The fuel injection timing, ignition timing, and the like are set on the basis of the above.

However, the target average effective pressure Pe
Is not particularly problematic in the compression stroke injection mode,
When applied in the intake stroke injection mode, for example, in an environment where the intake air amount is small, such as at high altitudes or in summer, the load between the actually obtained engine load and the load corresponding to the target average effective pressure Pe is Differences occur, and accurate fuel injection timing, ignition timing, and the like cannot be obtained, and as a result, the operating state of the engine may be unstable. In this case, it is conceivable to correct the target average effective pressure Pe as appropriate, but this is not preferable because the calculation becomes complicated.

For example, Japanese Patent Publication No. 52-6414 discloses a means for more accurately setting the fuel injection timing, ignition timing, and the like based on the air flow rate.
The technique disclosed in this publication is applied only when the engine is under a low load, and is not practical. The present invention has been made based on the above-described circumstances, and an object of the present invention is to provide a cylinder capable of easily ensuring a stable operation state regardless of whether the fuel injection timing is a compression stroke or an intake stroke. It is an object of the present invention to provide an internal injection type spark ignition type internal combustion engine.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a fuel injection valve for directly injecting fuel into a combustion chamber is provided. Operating state detecting means for detecting an operating state of an acceleration operating member in an in-cylinder injection type spark ignition type internal combustion engine capable of selecting between an intake stroke injection mode for performing fuel injection and a compression stroke injection mode for mainly performing fuel injection in a compression stroke An engine rotation speed detecting means for detecting an engine rotation speed, an intake air amount detecting means for detecting an intake air amount guided to the combustion chamber, and at least a fuel injection amount phase.
Combustion control means for performing combustion control based on a combustion parameter including a related value and a corrected intake air amount correlation value, and when the compression stroke injection mode is selected, the fuel injection amount correlation value and
While the corrected intake air amount correlation value is set by a first load correlation value based on the engine rotation speed and the output result of the acceleration operation state detecting means, when the intake stroke injection mode is selected, the fuel injection amount correlation value is set. and sets the second load correlation value based on the output result of the previous SL intake air amount detecting means a value, the said correction intake air amount correlation value first
And combustion parameter setting means for setting based on the load correlation value .

Accordingly, the direct injection type spark ignition type internal combustion engine has at least a fuel injection amount correlation value and a corrected intake air amount correlation value.
While combustion control is performed on the basis of the various combustion parameters including a value, when the compression stroke injection mode is selected, fuel
The fuel injection amount correlation value and the corrected intake air amount correlation value are determined based on an engine rotation speed and an output result of the acceleration operation state detecting means.
Is set by the load correlation value. On the other hand, when the intake stroke injection mode is selected, the fuel injection amount correlation value is set based on the second load correlation value based on the output result of the intake air amount detection means, and the corrected intake amount correlation value is set to the first Load correlation
Ru is set by the value. With this, the fuel injection amount correlation value and
Correcting the intake quantity correlation value, both correlated with the engine load that requires large active, is <br/> set based on more appropriate load correlation value, whether always good combustion control regardless of the fuel injection mode Is performed, and the stable operation state of the engine is maintained. Therefore, when the in-cylinder injection spark ignition type internal combustion engine is mounted on a vehicle, drivability is improved.

Further, in the invention according to claim 2, the intake stroke
Selection switching between the injection mode and the compression stroke injection mode,
The first operation according to the output result of the acceleration operation state detection means
Is performed based on the load correlation value is characterized in Rukoto. Therefore, the first load correlation value and the engine speed
Relatively easily based on the output result of the quick operation state detection means
What is required is the intake stroke injection mode and compression stroke
Switching between the injection mode and the injection mode is performed based on the first load correlation value.
Easier and more accurate than based on the second load correlation value
Will be implemented.

[0010] Also, in the invention of claim 3, wherein the combustion parameter
The meter contains the amount of EGR gas circulated to the intake air,
The burning parameter setting means selects the compression stroke injection mode.
When the first load is selected, the EGR gas amount is changed to the first load.
It is characterized by being set by a correlation value . Therefore,
When the compression stroke injection mode is selected, the EGR gas
The quantity is highly correlated with the required engine load,
Set by an appropriate first load correlation value, a stable
The driving condition of the gin is maintained and drivability is improved.
You .

[0011] Also, in the invention of claim 4, wherein the combustion parameter
The meter includes the ignition timing of the spark plug and the combustion parameter.
Data setting means selects the compression stroke injection mode.
Sometimes, the ignition timing is determined by the first load correlation value.
Set to is characterized in Rukoto. Therefore, compression stroke injection
When the mode is selected, the ignition timing
The first load is more correlated with the engine load and is more appropriate
Set by the correlation value, the stable engine operating condition
It is maintained and drivability is improved .

[0012]

[0013]

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing one embodiment of a control device for an internal combustion engine according to the present invention mounted on a vehicle. Hereinafter, the configuration of the control device for the internal combustion engine will be described with reference to FIG.

The engine 1 is capable of performing fuel injection in the compression stroke (late injection mode) together with fuel injection in the intake stroke (first injection mode), and combustion at a lean air-fuel ratio, that is, a lean air-fuel ratio. In-cylinder in-line four-cylinder gasoline engine is applicable. In the in-cylinder injection type engine 1, an EGR device (exhaust gas recirculation device) that performs an intake device and an exhaust gas recirculation (EGR) including a combustion chamber.
Are designed exclusively for in-cylinder injection, and can easily be operated at a rich air-fuel ratio, a stoichiometric air-fuel ratio (stoichio) AFS, and a lean air-fuel ratio.

The cylinder head 2 of the engine 1 is also provided with an electromagnetic fuel injection valve 4 together with an ignition plug 3 for each cylinder, so that fuel is directly injected into the combustion chamber 5. On the top surface of the piston 7 slidably held by the cylinder 6, a hemispherical depression, that is, a cavity 8 is formed at a position where the fuel spray from the fuel injection valve 4 reaches in the latter half of the compression stroke. ing. The compression ratio of the engine 1 is set higher (for example, about 12) than that of the intake pipe injection type. The DOHC4 valve type is adopted as the valve operating mechanism.
In the upper part of the table, to drive the intake and exhaust valves 9 and 10, respectively,
An intake camshaft 11 and an exhaust camshaft 12 are rotatably supported.

The cylinder head 2 has both camshafts 1
An intake port 13 is formed in a substantially upright direction so as to pass through between the intake ports 1 and 12, and an intake flow passing through the intake port 13 is tumbled in the combustion chamber 5 in a direction opposite to a normal tumble flow. A reverse tumble flow, which is a flow, can be generated. On the other hand, the exhaust port 14 is formed in a substantially horizontal direction similarly to a normal engine, but a large-diameter exhaust gas recirculation port, that is, an EGR port 15 is branched obliquely downward.

In FIG. 1, reference numeral 16 denotes a water temperature sensor for detecting a cooling water temperature Tw. Reference numeral 17 denotes a vane type crank angle sensor that outputs a crank angle signal SGT at a predetermined crank position (for example, 5 ° BTDC and 75 ° BTDC) of each cylinder. The engine rotation speed Ne can be detected based on the Reference numeral 19 denotes an ignition coil that outputs a high voltage to the ignition plug 3. A camshaft that rotates at half the number of revolutions of the crankshaft is provided with a cylinder discrimination sensor (not shown) that outputs a cylinder discrimination signal SGC. It is identifiable whether or not it is.

The intake port 13 is provided with a throttle body 23, a stepper motor type # 1 ABV (first air bypass valve) 24, an air flow sensor 32, and an air cleaner 22 through an intake manifold 21 having a surge tank 20. Tube 25 is connected. The intake pipe 25 has a large-diameter air bypass pipe 26 that bypasses the throttle body 23 and intakes air to the intake manifold 21.
A large # 2 ABV (second air bypass valve) 27 of a linear solenoid type is provided in the pipeline. The air bypass pipe 26 has a flow passage area similar to that of the intake pipe 25, and has a # 2ABV 27
When the engine 1 is fully opened, intake of an amount required in the low to medium speed range of the engine 1 is enabled.

The throttle body 23 has a butterfly type throttle valve 28 for opening and closing the flow path, and a throttle position sensor (a throttle valve opening sensor as a throttle valve opening sensor for detecting the opening of the throttle valve 28, that is, the throttle opening θth. Hereinafter, referred to as TPS) 29,
Detecting the fully closed state of the throttle valve 28 and detecting the engine 1
And an idle switch 30 for recognizing the idling state. Actually, the TPS 29 outputs a throttle voltage VTH corresponding to the throttle opening θth, and the throttle opening θth is recognized based on the throttle voltage VTH.

The air flow sensor 32 detects the amount of intake air Qa, and for example, a Karman vortex flow sensor is used. The intake air amount Qa may be obtained from a boost pressure sensor attached to the surge tank 20 and from the intake pipe pressure detected by the boost pressure sensor. On the other hand, the exhaust port 14 is connected via an exhaust manifold 41 to which an O ₂ sensor 40 is attached.
Exhaust pipe 4 provided with three-way catalyst 42 and muffler (not shown)
3 are connected. In addition, the above EGR port 15
Is connected upstream of the intake manifold 21 via a large-diameter EGR pipe 44, and a stepper motor type EGR valve 45 is provided in the pipeline.

The fuel tank 50 is installed at the rear of the vehicle (not shown). The fuel stored in the fuel tank 50 is sucked up by an electric low-pressure fuel pump 51 and fed to the engine 1 via a low-pressure feed pipe 52. The fuel pressure in the low-pressure feed pipe 52 is regulated to a relatively low pressure (low fuel pressure) by a first fuel pressure regulator 54 interposed in the return pipe 53. Engine 1
Supplied to the high-pressure feed pipe 5 by a high-pressure fuel pump 55 attached to the cylinder head 2.
The fuel is supplied to each fuel injection valve 4 through the delivery pipe 6 and the delivery pipe 57.

The high-pressure fuel pump 55 is, for example, of a swash plate axial piston type, is driven by the exhaust-side camshaft 12, and operates at 5M even when the engine 1 is idling.
A discharge pressure of Pa to 7 MPa or more can be generated. The fuel pressure in the delivery pipe 57 is regulated to a relatively high pressure (high fuel pressure) by a second fuel pressure regulator 59 interposed in the return pipe 58.

In the figure, reference numeral 60 denotes a second fuel pressure regulator 5.
9 is an electromagnetic type fuel pressure switching valve attached to 9. The fuel pressure switching valve 60 is capable of relieving fuel in the ON state, thereby reducing the fuel pressure in the delivery pipe 57 to a low fuel pressure. Reference numeral 61 denotes a high-pressure fuel pump 55
A part of fuel used for lubrication and cooling of
This is a return pipe that returns to 0.

In the cabin of the vehicle, an input / output device, a storage device (RO) for storing control programs, control maps and the like are provided.
M, RAM, BURAM, etc.), central processing unit (CP
U), an ECU (Electronic Control Unit) 70 including a timer counter and the like is installed, and the ECU 70 performs comprehensive control of the engine 1. ECU7
The various sensors described above are connected to the 0 input side, and detection information from the various sensors and the like is input. EC
U70 determines the fuel injection mode, the fuel injection amount, the ignition timing, the amount of EGR gas introduced, etc., based on the detected information, and determines the fuel injection valve 4, ignition coil 19, EG
The drive control of the R valve 45 and the like is performed. Although the description is omitted on the input side of the ECU 70, in addition to the above various sensors,
Many switches and sensors (not shown) are connected, and various warning lights and devices (not shown) are also connected to the output side.

Next, the engine 1 configured as described above
The operation of the control device, that is, the content of combustion control of the engine 1 will be described. When the engine 1 is cold,
When the driver turns on the ignition key, the ECU
70 turns on the low-pressure fuel pump 51 and the regulator bypass valve 60 to supply low-fuel pressure fuel to the fuel injection valve 4.

When the driver operates the ignition key, the engine 1 is cranked by a cell motor (not shown), and at the same time, the ECU 70 starts combustion control. At this time, the ECU 70 selects the first-stage injection mode (that is, the intake stroke injection mode) and injects fuel so as to have a relatively rich air-fuel ratio. This is based on the fact that since the fuel vaporization rate is low when the engine is cold, misfires and emission of unburned fuel (HC) cannot be avoided if the fuel is injected in the late injection mode (that is, the compression stroke injection mode). The ECU 70 closes the # 2ABV 27 at the time of such a start. Therefore, in this case, the intake air to the combustion chamber 5 is generated by the gap of the throttle valve 28 or the # 1 ABV
24. Note that # 1ABV24 and # 2A
The BV 27 is centrally managed by the ECU 70,
The respective valve opening amounts are determined according to the required amount of intake air (bypass air) bypassing the throttle valve 28.

When the start of the engine 1 is completed as described above and the engine 1 starts idling, the high-pressure fuel pump 55 starts the rated discharge operation, and the EC is started.
U70 supplies high-pressure fuel to the fuel injection valve 4 by turning off the regulator bypass valve 60. At this time, the required fuel injection amount is obtained from the discharge pressure of the high-pressure fuel pump 55 and the valve opening time of the fuel injection valve 4, that is, the fuel injection time.

Until the cooling water temperature Tw rises to a predetermined value, the ECU 70 selects the first injection mode and injects fuel so as to obtain a rich air-fuel ratio as in the case of starting, and continues # 2ABV27. Closed state. The control of the idle speed according to the increase or decrease of the load on the auxiliary equipment such as the air conditioner is performed by the # 1 ABV 24 in the same manner as in the case of the intake pipe injection type engine.

As described above, when the engine is cold, substantially the same fuel injection control as in the case of the intake pipe injection type engine is performed. In this case, however, the fuel droplets adhere to the wall of the intake pipe 13. Since there is no control, the response and accuracy of the control are high.
Referring to FIG. 2, when the engine 1 is warmed up, the ECU
FIG. 3 is a block diagram showing a control procedure of the combustion control executed by 70, and FIG. 3 shows a flowchart of a routine for setting various combustion parameters in the combustion control. Hereinafter, the combustion control during warm-up will be described with reference to FIGS.

When the engine 1 is warmed up, the ECU 7
In step S10 of FIG. 3, 0 indicates various detected values, that is, throttle opening degree information θth based on the throttle voltage VTH from the TPS 29, the engine rotation speed Ne from the crank angle sensor 17, and the intake air amount information from the air flow sensor 32. Read Qa. Then, in step S12, the Pe calculation unit 80 in FIG. 2 uses the throttle opening degree information θth based on the throttle voltage VTH from the TPS 29.
And engine speed information N from the crank angle sensor 17
Based on e, a target output, that is, a target average effective pressure (first load correlation value) Pe is calculated. Actually, as shown in the Pe calculation unit 80 in the figure, a map indicating the relationship between the throttle opening information θth and the engine rotation speed Ne is set in advance, and the target average effective pressure Pe is read from this map. Can be

Next, in step S14, the Ev calculating unit 82 in FIG. 2 uses the volumetric efficiency (second load correlation value) based on the intake air amount information Qa from the air flow sensor 32.
Calculate Ev. As described above, when the target average effective pressure Pe and the volumetric efficiency Ev are obtained, in addition to the signal of the engine rotation speed Ne, the respective signals of the target average effective pressure Pe and the volumetric efficiency Ev correspond to the target A / A in FIG. It is supplied to an F calculation unit 90, an injection end timing calculation unit 92, an ignition timing calculation unit 94, and an EGR amount calculation unit 96. These target A / F calculator 90, injection end timing calculator 92, ignition timing calculator 94, EGR amount calculator 96
Are target air-fuel ratios (fuel injection amount correlation values) A / F
(Hereinafter referred to as target A / F), fuel injection end timing (fuel injection amount correlation value) Tend, ignition timing Sa, EGR amount Legr
Is a block for setting various combustion parameters.

The target A / F calculator 90, the injection end timing calculator 92, the ignition timing calculator 94, and the EGR amount calculator 9
6, a plurality of combustion parameter setting maps based on the engine speed Ne and the target average effective pressure Pe, and a plurality of combustion parameter setting maps based on the engine speed Ne and the volume efficiency Ev are provided. Specifically, Goal A /
The F calculation unit 90, the injection end timing calculation unit 92, and the ignition timing calculation unit 94 are respectively set based on the engine rotation speed Ne and the target average effective pressure Pe, and the fuel injection mode is set to the late injection lean mode (see FIG. 4 described later). ), The engine speed Ne and the volumetric efficiency Ev, and the fuel injection mode is set to the first injection mode (first injection lean mode, stoichiometric feedback mode or open mode in FIG. 4 described later). Loop mode) is provided.

Here, when the fuel injection mode is the latter injection mode, the combustion parameter is set based on the target average effective pressure Pe, and when the fuel injection mode is the former injection mode, the combustion parameter is set based on the volume efficiency Ev. This is because, in the late injection mode in which fuel is injected in the compression stroke, the engine load has a large correlation with the target average effective pressure Pe, while on the other hand, in the early injection mode in which fuel is injected in the intake stroke. This is because the injection mode has a large correlation with the volume efficiency Ev.

Incidentally, regarding the late injection lean mode,
Two types of maps are provided for the case where EGR is performed and for the case where EGR is not performed. Regarding the stoichiometric feedback mode or the open loop mode of the ignition timing calculation unit 94, the case where EGR is performed is also performed. Two types of maps are provided. Also,
In the EGR amount calculation unit 96, a map which is set based on the engine speed Ne and the target average effective pressure Pe and is used in the late injection lean mode, and which is set based on the engine rotation speed Ne and the volumetric efficiency Ev and which is set in the first injection mode. A map to be used is provided. Here, two types of maps are respectively set when the transmission (not shown) is in the neutral range (N range) and when it is not.

Then, returning to the flowchart of FIG. 3, after step S15, in step S16, the target A / F calculator 90, the injection end timing calculator 92, and the ignition timing calculator 9
4. In the EGR amount calculation unit 96, the determination of switching between the maps of the first injection mode and the second injection mode is executed. That is,
In step S15, the current fuel injection mode is determined. In step S16, it is determined whether the fuel injection mode is the late injection mode or the previous injection mode based on the determination result of step S15.

Referring to FIG. 4, there is shown a fuel injection mode setting map provided in ECU 70. In step S15, the fuel injection mode is appropriately determined according to this map. Referring to the map of FIG. 4, the fuel injection mode is based on the engine speed Ne and the target average effective pressure Pe.
Alternatively, it can be switched in accordance with the volume efficiency Ev. More specifically, regarding the switching between the late injection lean mode and the previous injection lean mode and the switching between the latter injection lean mode and the stoichiometric feedback mode, that is, the switching between the latter injection mode and the earlier injection mode, the engine speed Ne and the target This is performed in accordance with the average effective pressure Pe. On the other hand, regarding the switching between the previous injection lean mode and the stoichiometric feedback mode, and the switching between the stoichiometric feedback mode and the open loop mode, that is, the switching between the previous injection mode. Is performed in accordance with one of the target average effective pressure Pe and the volumetric efficiency Ev.

Here, the reason why the volume efficiency Ev is not used for switching between the late injection mode and the first injection mode is that, in the latter injection mode, # 1ABV24 and # 2ABV are not used.
This is because the volume efficiency Ev based on the air flow sensor 32 becomes a substantially full open value in the entire region because a large amount of bypass air is introduced by the air flow sensor 27, and in this case, the volume efficiency Ev cannot be a correlation value of the engine load.

Then, based on the fuel injection mode obtained from the map of FIG. 4, it is determined in step S16 whether the fuel injection mode is the latter injection mode. If the determination result is true (Yes) and the fuel injection mode is the late injection mode, the process proceeds to step S20. On the other hand, if the determination result is false (No) and the fuel injection mode is the first injection mode, Goes to step S22.

In step S20, since the fuel injection mode is the late injection mode, the target A / F calculator 90
Injection end timing calculator 92, ignition timing calculator 94, EGR
In each block of the amount calculation unit 96, a map set based on the engine rotation speed Ne and the target average effective pressure Pe is selected, and the target A / F, the injection end timing Tend,
Each combustion parameter of the ignition timing Sa and the EGR amount Legr is set. Note that, as described above, in the late injection mode, E
The map is used properly according to the presence or absence of GR.

Thus, when the fuel injection mode is the latter injection mode, each combustion parameter is suitably set based on the target average effective pressure Pe having a high correlation with the engine load in the latter injection mode. By the way, as shown in FIG. 2, the signal of the target average effective pressure Pe is D / F
It is also supplied to the bypass air amount calculation unit 98 via the filter 84. Therefore, in this step S20, the engine rotational speed Ne is also determined for the bypass air amount (corrected intake air amount correlation value) Qabv that bypasses the air bypass pipe 26.
And the target average effective pressure Pe.

On the other hand, in step S22, since the fuel injection mode is the former injection mode, the target A / F calculator 90, the injection end timing calculator 92, the ignition timing calculator 94,
In each block of the EGR amount calculation unit 96, a map set based on the engine rotation speed Ne and the volume efficiency Ev is selected, and the combustion parameters of the target A / F, the injection end timing Tend, the ignition timing Sa, and the EGR amount Legr are selected. Is set. As described above, in the first-stage injection mode, a map corresponding to the first-stage injection lean mode, the stoichiometric feedback mode, and the open loop mode is appropriately selected and applied.

Thus, when the fuel injection mode is the first injection mode, each combustion parameter is suitably set based on the volume efficiency Ev having a high correlation with the engine load in the first injection mode. As described above, in the first injection mode, the volume efficiency Ev is used to set each combustion parameter. More specifically, when the target average effective pressure Pe is used, the engine 1 Tends to increase and decrease with a good response in response to a change in the target average effective pressure Pe. In particular, this tendency is remarkable in a region where the engine load is large when the first injection mode is selected, while the volumetric efficiency Ev This is because response is slow and response to output torque is slow. That is, if control is performed using the target average effective pressure Pe in the first injection mode, the output torque of the engine 1 can be extremely easily increased even if the driver unconsciously operates the accelerator pedal (not shown) slightly. However, if the volume efficiency Ev is used, the output torque follows slowly, so that the vehicle can be driven regardless of the slight change of the accelerator pedal. Driving stability is maintained.

In the next step S24, the bypass air amount Q
abv is set. However, the bypass air amount Qabv is set based on the engine speed Ne and the target average effective pressure Pe, as in the case of the latter-stage injection mode. This is the bypass air amount (corrected intake amount correlation value) Qab
The variable v controls the intake air amount Qa, and the volume efficiency Ev is determined according to the intake air amount Qa.

That is, if the bypass air amount Qabv is determined from the volumetric efficiency Ev, the intake air amount Qav is the sum of the bypass air amount Qabv and the intake air amount passing through the throttle valve 28. Quantity Qab
The volume efficiency Ev also changes according to the change in v, and this volume efficiency Ev
The phenomenon that the bypass air amount Qabv changes again according to the change of v is repeated. As a result, the bypass air amount Qabv
It takes time for v to reach a constant value, which affects each combustion parameter and deteriorates the followability of the output torque of the engine 1, which is not preferable.

Also, the volumetric efficiency Ev originally changes with a delay from the change in the throttle opening θth. Therefore, when trying to set the bypass air amount Qabv using the volumetric efficiency Ev, the timing of determining the bypass air amount Qabv is delayed, which also deteriorates the followability of the output torque of the engine 1. Therefore, it can be said from this that it is better to set the bypass air amount Qabv not from the volume efficiency Ev but from the target average effective pressure Pe based on the throttle opening θth.

As described above, in this case, various combustion parameters are obtained by selectively using the load correlation value between the late injection mode and the first injection mode, such as the target average effective pressure Pe and the volume efficiency Ev. Therefore, in the engine 1,
Combustion control can be performed using an appropriate load correlation value for each mode. As described above, the target A /
F, the fuel injection end timing Tend, the ignition timing Sa, the EGR amount Legr, and the bypass air amount Qabv are set.
Regarding / F, the target A / F signal is supplied to the Tinj calculating section 102 in FIG. 2, and the Tinj calculating section 102 sets the fuel injection time Tinj. Then, a signal corresponding to the fuel injection time Tinj is supplied to the fuel injection valve 4, and as described above, an amount of fuel corresponding to the fuel injection time Tinj is injected from the fuel injection valve 4. At this time, a signal corresponding to the fuel injection end timing Tend is also supplied to the fuel injection valve 4 at the same time, and the fuel injection timing is determined according to this signal.

The ignition timing Sa signal indicates that the ignition coil 19
And the EGR amount Legr signal is supplied to the EGR valve 45, and the bypass air amount Qabv signal is supplied to # 1ABV and # 2ABV, respectively, whereby optimal combustion control is performed. Therefore, for example, when the engine 1 is in a low load region such as during idling or low-speed running, the fuel injection mode is set to the late injection lean mode based on FIG. 4, and fuel injection is performed during the compression stroke, The fuel injection amount is determined so as to achieve a lean target A / F (for example, A / F = about 30 to 40) based on the target average effective pressure Pe.
The ignition timing Sa and the EGR amount Legr are set based on e, and good combustion control is performed.

The combustion in the late injection lean mode will be described in more detail. In the in-cylinder injection type engine 1, the cavity 8 is formed on the upper surface of the piston 7 as described above. From this, the intake port 13
Of the fuel and the intake air, that is, the fuel spray is injected into the ignition plug 3
Good concentration in the vicinity. As a result, a mixture near the stoichiometric air-fuel ratio AFS is always formed in a layer around the spark plug 3 at the time of ignition. Therefore, in the latter-stage injection mode, good ignitability is ensured even at a lean air-fuel ratio as a whole.

Further, for example, when the engine 1 is in the middle load range as in the case of running at a constant speed, the fuel injection mode is set to the first injection lean mode or the stoichiometric feedback mode based on FIG. In the first-stage injection lean mode, the fuel injection is performed in the intake stroke, and a relatively lean target A / F (for example, A
/ F = about 20 to 23), the ignition timing Sa is set based on the volumetric efficiency Ev, and good combustion control is performed.

On the other hand, in the stoichiometric feedback mode, fuel injection is also performed in the intake stroke, and the volumetric efficiency Ev
The ignition timing Sa and the EGR amount Legr are set on the basis of the air-fuel ratio feedback control based on the output voltage of the O ₂ sensor 40. Is controlled to become the stoichiometric air-fuel ratio AFS.

In the first injection mode, especially when the engine speed Ne is relatively low, the correlation between the engine load and the volumetric efficiency Ev is very good, and therefore, it is frequently used during normal constant speed running. In such a middle load range where the injection mode is in the early period and the engine rotation speed Ne is relatively low, the combustion control is extremely good.

Further, for example, when the engine 1 is in a high load range such as during rapid acceleration or high-speed running, the fuel injection mode is set to the open loop mode based on FIG. The selected fuel injection is performed in the intake stroke, the target A / F is set based on the volumetric efficiency Ev so as to obtain a relatively rich air-fuel ratio, and the ignition timing Sa is also set based on the volumetric efficiency Ev. ,
Good combustion control is performed.

When coasting during middle-to-high speed traveling, etc.,
The fuel injection mode is a fuel cut mode as shown in FIG. 4, in which case the fuel injection is stopped. This fuel cut is immediately stopped when the engine rotation speed Ne falls below the return rotation speed or when the driver depresses the accelerator pedal. By the way, when the engine 1 and the automatic transmission are combined, it is preferable that the hydraulic control of the friction clutch for shifting is also performed based on the target average effective pressure Pe instead of the volumetric efficiency Ev. This is based on the fact that the response of the control is slow in the volumetric efficiency Ev, as described above, and is intended to prevent the output torque of the engine 1 from being inconsistent with the selected shift speed, that is, preventing a shift.

As described in detail above, in the in-cylinder injection spark ignition type internal combustion engine of the present invention, when the engine 1 is in a low load range such as during idling operation or low speed running, the fuel injection mode is set. When the latter-stage injection lean mode is selected, while the engine 1 is in a high-load region, such as when running at medium to high speed, the former-stage injection mode is selected and the combustion control of the engine 1 is performed. Further, in the latter injection mode, various combustion parameters are set based on the target average effective pressure Pe which has a large correlation with the engine load when performing the fuel injection in the compression stroke. When fuel injection is performed, various combustion parameters are set based on the volumetric efficiency Ev having a large correlation with the engine load. That is, in the in-cylinder injection spark ignition type internal combustion engine of the present invention, various combustion parameters are separately set for each fuel injection mode based on an appropriate load correlation value (Pe or Ev) to perform combustion control. I have to.

Therefore, according to the in-cylinder injection type spark ignition type internal combustion engine, the operating performance of the engine 1 can always be sufficiently exhibited irrespective of the fuel injection mode, and the operating state is always maintained in a stable state. can do. Thereby, the traveling performance of the vehicle, that is, drivability can be improved. Further, since it is possible to always maintain a good combustion state, it is also possible to suppress the generation of harmful exhaust gas components.

[0056]

As described in detail above, claim 1 is as follows.
According to the direct injection type spark ignition type internal combustion engine, when the compression stroke injection mode is selected, the engine rotation speed and the first load correlation value based on the output result of the acceleration operation state detection means are used as various combustion parameters . Fuel injection amount
Correlation value and can set the correction intake air amount correlation value, the intake stroke when the injection mode is selected, the fuel injection amount-phase based on the second load correlation value based on the output result of the inhaled air amount detecting means
And a supplementary value based on the first load correlation value.
A positive intake amount correlation value can be set .

[0057] Thus, by selectively loading the correlation value, complicated correction calculation process without, a fuel injection quantity correlation value as a combustion parameter based on a large load correlation value correlated with the engine load to request correction intake air amount Correlation values can be set appropriately, good combustion control can always be performed irrespective of the fuel injection mode, and a stable operating state of the engine can be maintained.

Therefore, when the in-cylinder injection spark ignition type internal combustion engine is mounted on a vehicle, drivability can be improved and generation of harmful exhaust gas components can be suppressed. Further, according to the in-cylinder injection type spark ignition internal combustion engine of the second aspect , the first load correlation value is
The output result of the engine speed and acceleration operation state detection means
The intake stroke is relatively easy to determine
The selection switching between the injection mode and the compression stroke injection mode
Easy and accurate implementation based on 1 load correlation value
It can be in.

According to the third aspect of the present invention, the compression stroke injection mode is selected.
Sometimes there is a strong correlation with the required engine load,
Set the EGR gas amount with the more appropriate first load correlation value
It is possible to improve the drivability while maintaining a stable operation state of the engine.

According to the fourth aspect of the present invention, the compression stroke injection mode is selected.
Sometimes there is a strong correlation with the required engine load,
The ignition timing can be set with a more appropriate first load correlation value.
To maintain stable engine operating conditions
Quality can be improved .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a direct injection type spark ignition type internal combustion engine of the present invention.

FIG. 2 is a block diagram showing a control procedure of combustion control executed by an ECU in FIG.

FIG. 3 is a flowchart showing a combustion parameter setting routine.

FIG. 4 is a diagram showing a determination map of a fuel injection mode.

[Explanation of symbols]

 Reference Signs List 1 engine 3 spark plug 4 fuel injection valve 17 crank angle sensor (engine rotation speed detecting means) 19 ignition coil 24 # 1ABV (first air bypass valve) 27 # 2ABV (second air bypass valve) 29 TPS (operating state detecting means) 32) Air flow sensor (intake air amount detection means) 70 Electronic control unit (ECU) 80 Pe calculation unit 82 Ev calculation unit 90 Target A / F calculation unit 92 Injection end timing calculation unit 94 Ignition timing calculation unit 96 EGR amount calculation unit 98 Bypass air amount calculation unit

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI F02D 41/18 F02D 41/18 H 41/34 41/34 E 45/00 366 45/00 366F F02P 5/15 F02P 5/15 B (56) References JP-A-5-99020 (JP, A) JP-A-8-144806 (JP, A) JP-A-4-252836 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/00-41/40 F02D 43/00-45/00 F20B 23/10 F02P 5/145-5/155

Claims (4)

(57) [Claims] 1. An intake stroke injection mode having a fuel injection valve for directly injecting fuel into a combustion chamber and performing fuel injection mainly in an intake stroke according to an operation state, and a compression stroke injection mainly performing fuel injection in a compression stroke In the in-cylinder injection type spark ignition internal combustion engine capable of selecting a mode, an acceleration operation state detection means for detecting an operation state of an acceleration operation member; an engine rotation speed detection means for detecting an engine rotation speed; An intake air amount detecting means for detecting an intake air amount to be guided, and at least a fuel injection amount correlation value and a corrected intake air amount correlation value.
A combustion control means for performing combustion control on the basis of the no-combustion parameter, when the compression stroke injection mode is selected, the fuel
While the fuel injection amount correlation value and the corrected intake air amount correlation value are set by a first load correlation value based on the engine rotation speed and the output result of the acceleration operation state detection means, when the intake stroke injection mode is selected , The fuel injection amount
And it sets the second load correlation value based a correlation value in the output of the previous SL intake air amount detecting means, the correction intake
And a combustion parameter setting means for setting a quantity correlation value based on the first load correlation value. An in-cylinder injection spark ignition type internal combustion engine, comprising: 2. The method according to claim 1, wherein the selection switching between the intake stroke injection mode and the compression stroke injection mode is performed based on the first load correlation value according to an output result of the acceleration operation state detection means. to claim 1 Symbol mounting cylinder injection type spark-ignition internal combustion engines. 3. The combustion parameters are recirculated to the intake air.
An EGR gas amount, wherein the combustion parameter setting means includes:
When the compression stroke injection mode is selected, the E
Setting the GR gas amount by the first load correlation value
The in-cylinder injection type spark according to claim 1 or 2, characterized in that:
Ignition internal combustion engine. 4. The method according to claim 1, wherein the combustion parameter is ignition of a spark plug.
The combustion parameter setting means includes the compression
When the stroke injection mode is selected, the ignition timing
It is set by the first load correlation value.
The in-cylinder injection spark ignition internal combustion engine according to claim 1 or 2.
engine.