JP2002276402A - Fuel injection control device of cylinder injection type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device of a cylinder injection type internal combustion engine capable of performing division injection even when a required fuel injection amount is small and maintaining diffuisbility of the injected fuel through performing of the division injection. SOLUTION: The electronic control device 30 of the internal combustion engine 10 controls a fuel injection valve 14 so as to dividedly inject fuel of an amount equal to the required fuel injection amount based on an engine operating state when temperature of the engine is low to cylinders #1 to #6. In performing the division injection, the electronic control device 30 performs a cylinder reducing operation when an amount of the divided and injected fuel is determined to be lower than a minimum injection amount of the fuel injection valve 14. When the fuel injection in some of the cylinders is stopped by the cylinder reducing operation, the electronic control device 30 controls the fuel injection valve 14 to increase the required fuel injection amount in the operating cylinder and divide and inject fuel of an amount equal to the increased required fuel injection amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control apparatus for a direct injection internal combustion engine which directly injects fuel from a fuel injection valve into a cylinder.

[0002]

2. Description of the Related Art In a direct injection type internal combustion engine in which fuel is directly injected into a cylinder from a fuel injection valve, atomization of injected fuel is difficult to be promoted at a low engine temperature, and its diffusivity tends to deteriorate. is there. The deterioration of the diffusibility of the injected fuel may cause the combustion state to become unstable, resulting in an increase in smoke and a decrease in engine output.

Therefore, conventionally, for example, Japanese Patent Laid-Open No. 2000-4
As shown in Japanese Patent No. 5840, at such a low engine temperature, an amount of fuel (required fuel injection amount) required according to an engine operating state such as an engine load is not injected at a time.
This is divided into the first half and the second half of the intake stroke for injection. By performing such a so-called split injection, it is possible to ensure good diffusibility of the injected fuel even at a low engine temperature where atomization of the injected fuel is difficult to promote.

[0004]

By the way, when the required fuel injection amount required according to the engine operating state decreases,
During the split injection, the fuel injection amount of each fuel injection may be smaller than the minimum injection amount that can be controlled by the fuel injection valve. Therefore, in such a case, the execution of the split injection is stopped, and the amount of fuel equal to the required fuel injection amount is injected at once from the fuel injection valve.

[0005] However, if the split injection is stopped in this manner, it is no longer possible to ensure good diffusibility of the injected fuel at a low engine temperature, and as a result, the combustion state becomes unstable and smoke is not generated. An increase or a decrease in engine output cannot be avoided.

The present invention has been made in view of the above circumstances, and an object of the present invention is to enable execution of split injection even when a required fuel injection amount is small, and to execute injection fuel injection through execution of the split injection. It is an object of the present invention to suppress the deterioration of the diffusivity and to suppress the increase in smoke and the decrease in engine output due to the deterioration.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, when the engine temperature is low, an amount of fuel equal to a required fuel injection amount required in accordance with an engine operating state is supplied to a cylinder. In a fuel injection control device for an in-cylinder injection type internal combustion engine that controls a fuel injection valve for in-cylinder injection so that split injection is performed in which split injection is performed, when performing the split injection, some of the cylinders The required fuel injection amount in the working cylinder is increased by executing the reduced cylinder operation in which the fuel injection of the fuel injection is stopped, and the same amount of fuel as the increased required fuel injection amount is dividedly injected in the working cylinder. Control means for controlling the fuel injection valve as described above.

According to the above configuration, by executing the reduced cylinder operation, it is possible to increase the required fuel injection amount of the working cylinder by an amount corresponding to the cylinder in which the fuel injection has been stopped (stop cylinder). Even at the time of split injection, the amount of fuel to be split and injected can be made larger than the minimum injection amount of the fuel injection valve. Therefore, even when the required fuel injection amount is small, it is possible to execute the split injection, and by performing such split injection, it is possible to suppress the deterioration of the diffusibility of the injected fuel, and to increase the smoke and the engine output due to the increase. The decrease can be suppressed.

According to a second aspect of the present invention, in the fuel injection control apparatus for a direct injection internal combustion engine according to the first aspect, the control means controls the amount of fuel to be divided and injected when executing the divided injection. Is to execute the reduced-cylinder operation on condition that the injection amount is smaller than the minimum injection amount of the fuel injection valve.

In an in-cylinder fuel injection valve for directly injecting fuel into a cylinder, the fuel adhering to the injection port may be gradually carbonized and deposited as a deposit. Further, since most of the deposits thus accumulated are removed by the injection pressure or the like at the time of fuel injection, the accumulation of the deposits hardly proceeds in the fuel injection valve of the working cylinder in which the fuel injection is performed. On the other hand, in the fuel injection valve of the deactivated cylinder in which the fuel injection is stopped by the reduced cylinder operation, the deposit is not removed due to such fuel injection, so that the accumulation of the deposit proceeds.

According to the configuration of the second aspect of the present invention, since the reduced cylinder operation is performed only when it is necessary to execute the divided injection, the fuel injection is stopped. This makes it possible to minimize the accumulation of deposits in the fuel injection valves of the cylinders.

[0012] The invention described in claim 3 is the invention according to claim 1 or 2.
In the fuel injection control device for an in-cylinder injection internal combustion engine described in (1), the control means changes an operating cylinder during the reduced cylinder operation under a predetermined condition.

According to the configuration of the third aspect of the invention, when executing the reduced cylinder operation, the operating cylinder is changed under a predetermined condition. Therefore, when executing the reduced cylinder operation, it is possible to suppress accumulation of a large amount of deposits on the fuel injection valve of the specific cylinder due to the suspension of the fuel injection in the specific cylinder for a long time.

According to a fourth aspect of the present invention, in the fuel injection control apparatus for a direct injection internal combustion engine according to the third aspect, the control means integrates an amount of fuel injected into the working cylinder during the reduced cylinder operation. The operating cylinder is changed on condition that the fuel injection amount integrated value is equal to or more than a predetermined amount.

In removing deposits deposited on the fuel injection valve, the greater the fuel injection amount, the greater the removal action. In this regard, in the configuration of the invention described in claim 4, since the operating cylinder is changed on the condition that the integrated value of the fuel injection amount is equal to or more than the predetermined amount, the stop of the fuel injection accompanying the reduced cylinder operation is performed. Deposits accumulated on the fuel injector during the fuel injection can be suitably removed when fuel injection is restarted.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a fuel injection control device according to the present invention will be described below with reference to FIGS.

As shown in FIG. 1, an internal combustion engine 10 to which this fuel injection control device is applied has six cylinders # 1 to #.
In each of the cylinders # 1 to # 6, a fuel injection valve 14 for directly injecting fuel into the combustion chamber 12 is provided. The fuel injection by the fuel injection valves 14 of the cylinders # 1 to # 6 is performed in the first cylinder # 1 → the fifth cylinder # 5 → the third cylinder # 3 → the sixth cylinder # 6 → the second cylinder # 2 → the fourth cylinder. # 4 →
The processing is performed in the order of the first cylinder # 1 →.

These fuel injection valves 14 are connected to a high-pressure pump 18 via a common delivery pipe 16.
Further, the high-pressure pump 18 is connected to a fuel tank 22 via a feed pump 20.

After the fuel in the fuel tank 22 is supplied from the feed pump 20 to the high-pressure pump 18, the fuel is pressurized to a high pressure by the high-pressure pump 18 and sent to the delivery pipe 16. The high-pressure fuel thus sent to the delivery pipe 16 is distributed and supplied to each of the fuel injection valves 14, and is injected into the combustion chamber 12 from the injection holes 14 a when the fuel injection valves 14 are opened. The fuel injected into the combustion chamber 12 in this manner is burned after being mixed with the intake air introduced into the combustion chamber 12 through the intake passage 13. Then, the exhaust gas after combustion is discharged from the combustion chamber 12 to the exhaust passage 15. In the exhaust passage 15, catalytic converters 17a and 17b for purifying exhaust gas are arranged in a cylinder group (hereinafter, referred to as "first cylinder # 1") including a first cylinder # 1, a second cylinder # 2, and a third cylinder # 3.
Cylinder group (hereinafter referred to as “second cylinder group”) # 1 to # 3 and fourth cylinder # 4, fifth cylinder # 5, and sixth cylinder # 6 (hereinafter referred to as “second cylinder group”). , Respectively.

The amount of fuel actually injected from the fuel injection valve 14 depends on the fuel injection time, ie, the valve opening time of the fuel injection valve 14, and the fuel injection pressure, ie, the fuel pressure in the delivery pipe 16. Is determined. Both the fuel injection time and the fuel injection pressure are controlled by an electronic control unit 30 that performs various controls of the internal combustion engine 10.

The electronic control unit 30 includes a rotational speed sensor 31 for detecting an engine rotational speed, an accelerator sensor 32 for detecting a depression amount (accelerator opening) of an accelerator pedal (not shown), and a temperature of the engine cooling water. Detection signals of various sensors for grasping the operating state of the engine, such as a water temperature sensor 33 to be detected, are taken in. Other electronic control unit 3
The detection signal of the fuel pressure sensor 34 for detecting the fuel pressure in the delivery pipe 16 is also taken into 0.

The electronic control unit 30 includes an input circuit for receiving the detection signals, a drive circuit for driving the fuel injection valve 14 and the like, and various data such as an operation map required for various controls. 30 in which is stored
a.

The electronic control unit 30 sets a target value for the fuel pressure in the delivery pipe 16 based on the engine operating state, that is, a target value of the fuel injection pressure, and sets the fuel pressure based on the detection signal of the fuel pressure sensor 34. The actual value of is detected.
Then, the electronic control unit 30 performs feedback control of the discharge amount of the high-pressure pump 18 so that the actual fuel pressure matches the target value. As a result of controlling the discharge amount of the high-pressure pump 18, the fuel injection pressure is controlled according to the engine operating state.

Further, the electronic control unit 30 calculates a required value of the fuel injection amount (required fuel injection amount QINJ) based on the engine operating state (for example, engine speed, accelerator opening, engine cooling water temperature, etc.). Then, the fuel injection time is calculated based on the required fuel injection amount QINJ and the fuel injection pressure, and the opening and closing of the fuel injection valves 14 of the cylinders # 1 to # 6 is controlled based on the fuel injection time.

Next, the fuel injection control executed by the apparatus according to this embodiment will be described. FIG. 2 shows each fuel injection mode in the intake stroke injection in which the fuel injection is started during the intake stroke. In the present embodiment, this fuel injection mode is switched among "all cylinders simultaneous injection", "all cylinder split injection", and "reduced cylinder split injection".

For example, when it is determined that a good diffusibility of the injected fuel can be ensured, for example, when the engine temperature is high, or when the required fuel injection amount QINJ is large, a period for temporarily stopping the fuel injection during the split injection is secured. When it is determined that the fuel injection cannot be performed (or becomes extremely short), the fuel injection mode is set to all-cylinder collective injection. As shown in FIG. 2A, in the all-cylinder simultaneous injection, each of the cylinders # 1 to # 6 has a fuel injection time τ determined according to the required fuel injection amount QINJ and the fuel injection pressure (fuel pressure). Required fuel injection amount QIN
An amount of fuel equal to J is injected at one time.

On the other hand, it is determined that the diffusibility of the injected fuel is poor, and a period during which the fuel injection is temporarily stopped during the divided injection can be secured. Injection time τ1, τ2 during injection (FIG. 2
(B) is longer than the minimum energization time (minimum injection time) τmin that can be controlled by the fuel injection valve 14, the fuel injection mode is set to all-cylinder split injection. As shown in FIG. 2 (b), in this all-cylinder split injection, the required fuel injection amount Q
INJ is bisected and the bisected amount (QINJ /
2) and the fuel injection time τ1, determined according to the fuel injection pressure
With τ2 (τ1 = τ2), fuel is injected in the first half and the second half of the intake stroke, respectively.

On the other hand, although it is determined that the diffusibility of the injected fuel is poor and a period during which the fuel injection is temporarily stopped during the divided injection can be secured, as shown in FIG. And the fuel injection time τ1, τ2 in each fuel injection in the latter period is the minimum energization time τ of the fuel injection valve 14.
When it is determined to be shorter than min, the fuel injection mode is set to the reduced cylinder split injection. In this reduced-cylinder split injection, a reduced-cylinder operation is performed. Specifically, the first cylinder group # 1 to # 1
Of the # 3 and the second cylinder groups # 4 to # 6, the fuel injection in one cylinder group is stopped, and the fuel injection is executed only in the other cylinder group. Then, in the cylinder in which the fuel injection is performed, that is, in the working cylinder, fuel is injected in the first half and the second half of the intake stroke, respectively, as in the above-described all-cylinder split injection.

However, in this reduced-cylinder split injection, the required fuel injection amount Q in the working cylinder is set to offset the decrease in engine output due to the stoppage of fuel injection in one cylinder group.
The INJ is doubled by adding the amount of the idle cylinder, and the amount (= 2 · α · QINJ α: increase coefficient) obtained by adding the increase correction to compensate for the pump loss etc. in the idle cylinder is newly added. Is calculated as the required fuel injection amount QINJ. Then, the fuel equally divided into two (= α · QINJ) is injected in the first half and the second half of the intake stroke, respectively. As described above, when the reduced cylinder operation is performed, the required fuel injection amount QINJ in the working cylinder is increased at least twice or more as compared with the case where the full cylinder operation is performed.
As shown in (d), the fuel injection time τ1, τ2
Becomes longer than the minimum energization time τmin of the fuel injection valve 14. As a result, the amount of fuel to be divided and injected is also larger than the minimum injection amount of the fuel injection valve 14.

Next, the processing procedure of the above-described fuel injection control will be described in more detail with reference to the flowcharts of FIGS. The series of processes shown in this flowchart is repeatedly executed by the electronic control unit 30 each time the fuel injection timing of each of the cylinders # 1 to # 6 arrives.

In this series of processing, first, the required fuel injection amount QINJ is calculated based on the engine operating state (FIG. 3).
Step 100). Next, the fuel injection pressure is read based on the detection signal of the fuel pressure sensor 34 (step 11).
0). Then, the fuel injection time τ is calculated based on the required fuel injection amount QINJ and the fuel injection pressure (step 120).

Next, it is determined whether or not it is necessary to execute the split injection in order to ensure good diffusion of the injected fuel (step 130). Specifically, it is determined whether or not the engine is at a low temperature based on the fact that the engine cooling water temperature is lower than a predetermined temperature, and based on the fact that the engine speed is lower than the predetermined speed, the mixture of the air-fuel mixture in the combustion chamber 12 is determined. It is determined whether the flow speed is lower than a predetermined speed. And
When the engine temperature is low and the flow rate of the air-fuel mixture in the combustion chamber 12 is low, and it is determined that diffusion of the injected fuel due to the flow of the air-fuel mixture cannot be expected, it is determined that the split injection needs to be performed. (Step 130: YES).

When it is determined that the split injection needs to be executed, it is next determined whether or not the split injection can be actually executed (step 140). Here, the required fuel injection amount QINJ is large, and it is not possible to secure a period for temporarily stopping the fuel injection during the divided injection, or this period is extremely short. Is determined to be in a state in which the diffusibility of the sample cannot be improved. This determination is made based on a comparison result between the fuel injection time τ calculated in the previous process (step 120) and a value obtained by converting the intake stroke period into time based on the engine speed.

If it is determined that the split injection can be executed (step 140: YES), it is next determined whether or not the reduced cylinder operation is required (step 150). Specifically, the fuel injection time τ1, τ2 (= τ / 2) corresponding to the amount obtained by equally dividing the required fuel injection amount QINJ into two and the minimum energization time τmin of the fuel injection valve 14 are compared. It is determined that the reduced cylinder operation is necessary based on that τ1 and τ2 are shorter than the minimum energization time τmin, in other words, based on the fact that the amount of fuel to be divided and injected is less than the minimum injection amount of the fuel injection valve 14. You.

When it is determined that the reduced cylinder operation is necessary (step 150: YES), the required fuel injection amount QI corresponding to the execution of the reduced cylinder split injection as described above.
NJ is calculated based on the following equation (1) (step 180 in FIG. 4).

QINJ ← 2 · α · QINJ (1) α: increase coefficient Next, based on the following equation (2), when executing the reduced-cylinder split injection, the amount of fuel injected in the working cylinder is reduced. An integrated value (injected amount integrated value SQINJ) is calculated (step 1).
90).

SQINJ ← SQINJ + QINJ (2) However, when SQINJ ≧ 2 · SQL, SQINJ ←
"0" SQL: predetermined amount Then, the injection amount integrated value SQINJ is compared with the predetermined amount SQL (step 200), and the execution form of the reduced cylinder split injection (steps 210 and 220) is switched based on the comparison result.

That is, when the injection amount integrated value SQINJ is smaller than the predetermined amount SQL (step 200: YE
S), the fuel injection of the second cylinder group # 4 to # 6 is stopped, and the fuel injection is executed in the first cylinder group # 1 to # 3 (step 220). In this case, from the working cylinders, that is, the first cylinder groups # 1 to # 3, fuel of an amount obtained by bisecting the required fuel injection amount QINJ calculated through the processing of step 180 is injected in the first half and the second half of the intake stroke, respectively. Is done.

On the other hand, if the integrated injection amount SQINJ is equal to the predetermined amount S
When the engine speed is equal to or higher than QL (step 200: NO), the fuel injection of the first cylinder group # 1 to # 3 is stopped, and the fuel injection is executed in the second cylinder group # 4 to # 6 (step 210). In this case, similarly, the operating cylinder, that is, the second cylinder group # 4 to # 6, divides the required fuel injection amount QINJ calculated through the processing of step 180 into two equal parts, and supplies fuel in the first half and the second half of the intake stroke. Respectively.

As described above, the operating cylinders at the time of the reduced cylinder split injection are the first cylinder group # 1 to # 3 and the second cylinder group # 4.
The reason for switching between # 6 and # 6 is as follows.

That is, when fuel adheres to the injection hole portion 14a of the fuel injection valve 14, the fuel gradually carbonizes and accumulates as a deposit. Most of the deposits thus accumulated are removed by the injection pressure or the like at the time of fuel injection, so that the accumulation of the deposits in the working cylinder is difficult to progress. On the other hand, in the deactivated cylinder, the deposit is not removed due to the fuel injection, so that when the fuel injection is stopped for a long period of time, the accumulation of the deposit proceeds.

In addition, if the fuel injection in one of the first cylinder group # 1 to # 3 and the second cylinder group # 4 to # 6 is stopped for a long time, the corresponding cylinder group is stopped. There is a possibility that the catalyst temperature of the catalytic converters 17a and 17b provided is lowered, and the catalytic function thereof is lowered.

Therefore, in the present embodiment, by periodically changing the operating cylinder, the fuel injection in a specific cylinder is stopped for a long period of time. Is prevented from accumulating a large amount of deposits in the injection hole portion 14a) or reducing the catalytic function of the catalytic converters 17a and 17b.

In the case of removing deposits deposited on the fuel injection valve 14, the greater the fuel injection amount, the greater the removing action. Therefore, as the integrated value of the fuel injection amount increases, the amount of deposit removal also increases accordingly.

Therefore, in the present embodiment, the injection amount integrated value SQINJ in the working cylinder is monitored, and based on the fact that the injection amount integrated value SQINJ is equal to or more than the predetermined amount SQL, the operating cylinder is changed, so that the fuel injection is performed. The deposits accumulated on the fuel injection valve 14 during the stop are surely removed when the fuel injection is restarted.

On the other hand, when it is determined that it is not necessary to execute the split injection (step 130 in FIG. 3: NO), or when it is determined that the split injection cannot be executed (step 140 in FIG. 3: NO) ), All-cylinder collective injection is executed (step 170). When it is determined that the split injection needs to be executed and the split injection can be executed, but it is not necessary to execute the reduced cylinder operation (step 150 in FIG. 3: NO), all-cylinder split injection is executed (step 160).

When one of the all-cylinder collective injection, the all-cylinder split injection, and the reduced-cylinder split injection is executed in this manner, this series of processing is temporarily terminated. According to the present embodiment in which the fuel injection by the fuel injection valve 14 is controlled in the manner described above, the following functions and effects can be obtained.

By executing the reduced cylinder operation, the required fuel injection amount QINJ of the working cylinder can be increased by the number of the cylinders in which fuel injection has been stopped (stop cylinder). However, the amount of fuel to be divided and injected can be made larger than the minimum injection amount of the fuel injection valve 14. Therefore, even when the required fuel injection amount QINJ required according to the engine operating state is small, the execution of the split injection becomes possible, and the execution of the split injection suppresses the deterioration of the diffusibility of the injected fuel. As a result, an increase in smoke and a decrease in engine output can be suppressed.

The reduced-cylinder operation is executed on condition that the amount of fuel to be divided and injected is less than the minimum fuel injection amount of the fuel injection valve 14. Therefore, when it is necessary to execute the divided injection. Only the reduced-cylinder operation is executed, and the accumulation of deposits at the fuel injection valve with the stop of the fuel injection can be suppressed as much as possible.

When executing the reduced cylinder operation, it is possible to suppress accumulation of a large amount of deposits on the fuel injection valve 14 of a specific cylinder due to suspension of fuel injection in a specific cylinder for a long time. become.

When executing the reduced cylinder operation, each cylinder group # 1 to # 1
By stopping fuel injection in one of # 3, # 4 to # 6 for a long time, the same cylinder group # 1 to # 3, # 4 to # 6
Can be suppressed from decreasing the catalyst temperature of the catalytic converters 17a and 17b corresponding to the above.

The injection amount integrated value SQINJ in the operating cylinder is monitored, and based on the fact that the injection amount integrated value SQINJ becomes equal to or greater than the predetermined amount SQL, the operating cylinder is changed to the first cylinder group # 1 to # 1.
Since the switching is made between # 3 and the second cylinder group # 4 to # 6, the deposit accumulated on the fuel injection valve 14 is restarted while the fuel injection is stopped during the reduced cylinder operation. Can be suitably removed.

As described above, one embodiment of the present invention has been described, but this embodiment can be implemented by changing its configuration as follows. In the above embodiment, the fuel injection time τ1, τt2 and the minimum energization time τ of the fuel injection valve 14 when executing the split injection
The minimum injection amount of the fuel injection valve 14 is calculated based on the minimum energization time τmin and the fuel injection pressure, for example. The minimum injection amount may be directly compared with the amount of fuel to be divided and injected, and the necessity of the reduced cylinder operation may be determined based on the comparison result.

In the above embodiment, when the cylinders # 1 to # 6 are divided into two cylinder groups and the reduced cylinder split injection is executed,
The operating cylinder and the inactive cylinder are switched between the two cylinder groups. However, the operating cylinder and the inactive cylinder in the reduced cylinder split injection can be arbitrarily selected. For example,
Each of the cylinders # 1 to # 6 may be divided into three cylinder groups, and the operating cylinder and the inactive cylinder may be switched between these cylinder groups. Further, in this case, only the cylinders of one cylinder group among these cylinder groups are set as the operating cylinders, and the cylinders of the remaining two cylinder groups are set as the idle cylinders, or the cylinders of the two cylinder groups are set as the operating cylinders, and the remaining cylinders are set as the operating cylinders. The cylinders of one cylinder group can be used as idle cylinders.

In the above embodiment, the operating cylinders are assigned to the respective cylinder groups # based on the integrated injection amount SQINJ in the operating cylinders.
Although the change is made between 1 to # 3 and # 4 to # 6, the change of the working cylinder may be made based on, for example, the number of times of fuel injection in the working cylinder.

In the above embodiment, the fuel injection in three of the six cylinders is stopped when the reduced cylinder split injection is executed. For example, the split injection is executed with the number of deactivated cylinders. Fuel injection time τ1, τt
2 may be variably set in accordance with a result of comparison between the fuel injection valve 14 and the minimum energization time τmin. in this case,
For example, the above fuel injection time τ1, τt2 is the minimum energization time τ
It is desirable to increase the number of deactivated cylinders as the length becomes longer than min.

In the above embodiment, the fuel injection mode in the intake stroke injection is controlled to be switched among all-cylinder collective injection, all-cylinder split injection, and reduced-cylinder split injection. Is performed, the fuel injection mode can be controlled in a similar manner.

In the above embodiment, when performing the split injection, the required fuel injection amount QINJ is divided into two equal parts, and the amounts of the divided and injected fuel are made equal to each other. By dividing the QINJ with different ratios, it is also possible to set the amounts of fuel to be divided and injected differently.

In the above embodiment, the reduced-cylinder operation is performed on condition that the amount of fuel to be divided and injected is less than the minimum fuel injection amount of the fuel injection valve 14, but the divided injection is performed. In such a case, it is also possible to always perform the reduced cylinder operation.

In the above embodiment, an example in which the internal combustion engine to which the fuel injection control device is applied has six cylinders has been described. However, the fuel injection control device according to the present invention has five cylinders or less, or The present invention can be applied to an internal combustion engine having seven or more cylinders.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a direct injection internal combustion engine and a fuel injection control device thereof.

FIG. 2 is an explanatory diagram for explaining a fuel injection mode in an intake stroke injection.

FIG. 3 is a flowchart showing a processing procedure of fuel injection control.

FIG. 4 is a flowchart showing a processing procedure of fuel injection control.

[Explanation of symbols]

10 internal combustion engine, 12 combustion chamber, 13 intake passage, 14
... Fuel injection valve, 14a ... Injection hole, 15 ... Exhaust passage, 16
... Delivery pipe, 17a, 17b ... Catalyst converter,
18 high-pressure pump, 20 feed pump, 22 fuel tank, 30 electronic control unit, 31 rotational speed sensor,
32: accelerator sensor, 33: water temperature sensor, 34: fuel pressure sensor, # 1 to # 6: cylinders, # 1 to # 3: first cylinder group,
# 4 to # 6: the second cylinder group.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/06 335 F02D 41/06 335S 41/34 41/34 GHF term (Reference) 3G092 AA06 AA14 BB01 BB08 BB10 CA07 CB05 DE03S EA01 EA09 FA18 GA02 HB03X HB03Z HE01Z HE08Z HF08Z 3G301 HA04 HA07 JA01 JA21 KA02 KA05 LB04 MA24 MA26 NE01 NE19 PB08A PB08Z PE01Z PE08Z PF03Z

Claims (4)

[Claims] 1. A fuel injection system for in-cylinder injection so that when the engine is at a low temperature, split injection is performed in which fuel is split into a cylinder and injected in an amount equal to a required fuel injection amount required according to an engine operating state. In the fuel injection control device for a direct injection internal combustion engine that controls a valve, when performing the split injection, the required fuel injection in the active cylinder is performed by executing a reduced cylinder operation in which fuel injection in some of the cylinders is stopped. And in-cylinder injection control means for controlling the fuel injection valve so that the amount of fuel is increased and the same amount of fuel as the increased required fuel injection amount is divided and injected in the working cylinder. A fuel injection control device for an internal combustion engine. 2. The reduced-cylinder operation according to claim 1, wherein the control means executes the reduced-cylinder operation on condition that an amount of fuel to be divided and injected is less than a minimum injection amount of the fuel injection valve. A fuel injection control device for a direct injection internal combustion engine according to claim 1. 3. The fuel injection control device for a direct injection internal combustion engine according to claim 1, wherein the control means changes the operating cylinder during the reduced cylinder operation under a predetermined condition. 4. The control means accumulates the amount of fuel injected into the working cylinder during the reduced cylinder operation, and changes the working cylinder on condition that the fuel injection amount integrated value is equal to or more than a predetermined amount. The fuel injection control device for a direct injection internal combustion engine according to claim 3.