JP2002013436A - Fuel injector of cylinder injection internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injector of a cylinder injection internal combustion engine capable of properly removing the deposit accumulated in the injection hole part of a fuel injection nozzle while suppressing an engine output from unnecessarily increasing. SOLUTION: This controller of an internal combustion engine raises a fuel injection pressure when a cumulative injection amount SQINJ reaches a specified value SQ1 (timing t1), to stop the fuel injection of a second group of cylinders #4 to #6 and increase the fuel injection amount QINJ1 of a first group of cylinders #1 to #3 (timing t1 to t2). When the cumulative injection amount SQINJ reaches a specified value (SQ1+CLQ) (timing t2), the controller stops the fuel injection of the first group of cylinders #1 to #3 and increase the fuel injection amount QINJ2 of the second group of cylinders #4 to #6 (timing t2 to t3). When the cumulative injection amount SQINJ reaches a specified value (SQ1+2CLQ) (timing t3), the controller performs the normal fuel injection control for injecting fuel in all cylinders.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In a direct injection type internal combustion engine, fuel is injected directly into the cylinder from an injection hole of a fuel injection valve, and an air-fuel mixture having a high fuel concentration is unevenly distributed only near an ignition plug. Therefore, combustion at an air-fuel ratio extremely thinner than the stoichiometric air-fuel ratio, that is, so-called stratified combustion is realized.

[0003] In such an internal combustion engine, a part of the injected fuel may not be burned, and may remain in the injection hole of the fuel injection valve. When the fuel adheres to the injection hole in this way, the highly volatile component of the attached fuel evaporates due to the heat of the engine and the fuel injection valve, and the carbonized component in the fuel is deposited as a deposit in the injection hole. become. When the amount of the deposit increases, the injection characteristics of the fuel injection valve deteriorate, such as a decrease in the fuel injection amount and a change in the fuel spray shape.

Therefore, in the prior art, Japanese Patent Laid-Open No.
As proposed in Japanese Patent Laid-Open No. 6-64, when it is determined that the injection characteristics of the fuel injection valve have changed due to the accumulation of deposit, the fuel injection pressure is temporarily increased, and the injection force is increased by the increased penetration force of the injected fuel. The deposits deposited on the holes are removed.

[0005]

By increasing the fuel injection pressure in this way, it is possible to remove deposits deposited on the injection hole of the fuel injection valve and to recover its injection characteristics. However, simply increasing the fuel injection pressure increases the amount of fuel injected from the fuel injector per unit time and increases the total amount of fuel supplied to the internal combustion engine. Will be increased. For this reason, in the device described in the above publication, such an increase in the engine output is suppressed by setting the fuel injection time of the fuel injection valve short in accordance with the change of the fuel injection pressure.

However, when the fuel injection time is set to be short in this way, even if the fuel injection pressure is increased to increase the penetration force of the injected fuel, the penetration force acts on the deposit for a short time. become unable. For this reason, in the above-mentioned conventional apparatus, although the deposit accumulated in the injection hole portion of the fuel injection valve can be surely removed, its removal ability is naturally limited, and it is necessary to remove the deposit reliably. Then, there was still room for improvement.

The present invention has been made in view of such conventional circumstances, and has as its object to suitably remove deposits deposited on the injection hole of a fuel injection valve while suppressing unnecessary increase in engine output. It is an object of the present invention to provide a fuel injection device for an in-cylinder injection type internal combustion engine, which is capable of performing the following.

[0008]

The means for solving the above problems and the operation and effects thereof will be described below. According to the first aspect of the present invention, in a fuel injection device for an in-cylinder injection type internal combustion engine that directly injects fuel into a cylinder from an injection hole of a fuel injection valve, a timing at which deposits at the injection hole are to be removed is provided. Determining means for determining that there is, and when it is determined that the removal timing is reached, while reducing the fuel injection amount of the fuel injection valves in some cylinders, and reducing the fuel injection amount of the fuel injection valves in other cylinders Fuel injection control means for increasing the amount.

According to the above configuration, when it is time to remove the deposit in the injection hole portion, the fuel injection amount of the fuel injection valve in some cylinders is reduced, while the fuel injection amount in other cylinders is reduced. Since the fuel injection amount is increased, the fuel injection pressure is increased while securing sufficient fuel injection time to remove the deposit, or while maintaining the fuel injection pressure sufficient to remove the deposit. The fuel injection time can be set to a longer time. Therefore, the deposits deposited on the injection holes of the fuel injection valves in the other cylinders can be suitably removed.

Here, the operation of increasing or decreasing the fuel injection amount may be such that the fuel injection amount of the fuel injection valve is increased in all of the remaining cylinders except for the cylinder whose fuel injection amount is reduced. The fuel injection amount of the fuel injection valve in the cylinder of the section may be increased.

Regarding the other cylinders, whether the fuel injection amount of all of the remaining cylinders is increased or the fuel injection amount of some of the cylinders is increased, Even if the combustion explosion power in the other cylinders increases, it is offset by the decrease in the fuel explosion power in some of the cylinders due to the decrease in the combustion explosion power of the same cylinder. The required increase can be minimized.

According to a second aspect of the present invention, in the fuel injection system for a direct injection internal combustion engine according to the first aspect, the fuel injection control means controls a fuel injection amount of a fuel injection valve in some of the cylinders. It is said that the fuel injection of the fuel injection valve is stopped by decreasing the amount to "0".

According to the above configuration, the fuel injection amount of the fuel injection valves in the other cylinders can be increased more, and a more preferable removal ability can be secured.

According to a third aspect of the present invention, in the fuel injection system for a direct injection internal combustion engine according to the first or second aspect, the fuel injection control means includes a fuel injection valve for a fuel injection valve in the other cylinder. In increasing the amount, both the fuel injection time and the fuel injection pressure are to be increased.

According to the above construction, the penetration force of the injected fuel can be increased and the time during which the penetration force acts on the deposit can be ensured for a long time, so that a more preferable removal ability can be secured. become.

According to a fourth aspect of the present invention, in the fuel injection device for a direct injection internal combustion engine according to any one of the first to third aspects, the fuel injection control means includes: These cylinders and other cylinders are selected so that the fuel injection timing of the valves and the fuel injection timing of the fuel injection valves in the other cylinders come alternately.

Cylinder with increased fuel injection amount (increased cylinder)
When the combustion explosion at the engine is continuously repeated, the engine output gradually increases accordingly. Conversely, if the combustion explosion in the cylinder with the reduced fuel injection amount (reduced cylinder) is continuously repeated, the engine output gradually decreases accordingly. Therefore, for example, when the internal combustion engine is operated in such a manner that the combustion explosion in the increasing cylinder is repeated a plurality of times after the combustion explosion in the increasing cylinder is repeated a plurality of times, the fluctuation of the engine output becomes large. .

In this regard, according to the above configuration of the present invention, the fuel injection timing of some of the cylinders corresponding to the decreasing cylinder and the fuel injection timing of the other cylinders corresponding to the increasing cylinder are determined. Come alternately, so that such an increase in engine output fluctuation can be suppressed.

According to a fifth aspect of the present invention, in the fuel injection system for a direct injection internal combustion engine according to any one of the first to fourth aspects, the fuel injection control means performs the operation of increasing or decreasing the fuel injection amount. It is described that the operation is performed on condition that the engine load is larger than a predetermined value.

According to a sixth aspect of the present invention, in the fuel injection system for a direct injection internal combustion engine according to any one of the first to fifth aspects, the fuel injection control means includes means for increasing or decreasing the fuel injection amount. It is described that the operation is performed gradually as time elapses from the time when the determination unit determines that the removal time has come.

Since the combustion explosion in each cylinder of the internal combustion engine occurs intermittently, the engine output fluctuates, albeit slightly, so that the fuel injection amount in each cylinder differs as described above. However, such fluctuations in engine output are further increased. Further, the fluctuation of the engine output tends to become more remarkable when the engine load is low, in other words, when the engine output is relatively small.

When the fluctuation of the engine output increases,
The greater the speed of the increase, that is, the shorter the time required for the engine output to fluctuate from a small variation range to a large variation range, the more the variation in the engine output becomes more sensible.

[0023] In this respect, according to the above-described structure of the invention, the operation of increasing or decreasing the fuel injection amount in each of the cylinders is performed on condition that the engine load is larger than a predetermined value. Even if the engine output fluctuates due to the increase / decrease operation, this can be suppressed to a small value.

Further, according to the above configuration of the present invention, the operation of increasing or decreasing the fuel injection amount in each cylinder is performed gradually as time elapses from when it is determined that it is time to remove the deposit. As a result, it is possible to make it difficult for the user to feel such an increase in engine output fluctuation.

According to a seventh aspect of the present invention, in the fuel injection system for a direct injection internal combustion engine according to any one of the first to sixth aspects, the determining means includes a fuel injection amount for all cylinders or a specific cylinder. And the removal time is determined based on the fact that the integrated value exceeds a predetermined value.

The deposits on the injection hole of the fuel injection valve are caused by the adhesion of the injected fuel to the injection hole.
Also, as the injection amount in one fuel injection increases, the accumulation amount tends to increase.

According to the above configuration of the present invention, the amount of deposits can be estimated, and the timing of deposit removal can be appropriately determined based on the estimation result. .

According to an eighth aspect of the present invention, in the fuel injection system for a direct injection internal combustion engine according to any one of the first to seventh aspects, the determining means includes a weighting set in accordance with an engine operating state. Weighting is performed when integrating the fuel injection amount based on the coefficient.

According to a ninth aspect of the present invention, in the fuel injection system for a direct injection internal combustion engine according to any one of the first to eighth aspects, the determining means sets the weighting as the engine temperature increases. The coefficient is set to be large.

According to a tenth aspect of the present invention, in the fuel injection system for a direct injection internal combustion engine according to any one of the first to ninth aspects, the determining means determines that the lower the engine speed is, The weighting coefficient is set to be large.

[0031] Even when the integrated value of the fuel injection amount is the same, the more the fuel injection is performed under the engine operating condition in which the deposit tends to accumulate, the larger the accumulation amount of the deposit. For example, when the engine temperature becomes relatively high, evaporation of highly volatile components of the fuel adhering to the injection hole of the fuel injection valve is promoted, so that deposits are easily deposited. Further, when the engine rotation speed is relatively low, the period from the end of fuel injection to the start of the next fuel injection becomes longer, so that the evaporation time of the volatile component is secured longer. Also, deposits tend to accumulate at the injection hole.

In this regard, according to the configuration of the invention described in any one of claims 8 to 10, it is possible to accurately estimate the amount of the deposit in accordance with the tendency of the deposit to be changed according to the engine operating state. As a result, the timing for removing the deposit can be more appropriately determined.

In particular, according to the ninth or tenth aspect of the present invention, even if the evaporation degree of the volatile component contained in the attached fuel changes according to the engine temperature or the engine rotation speed, and the deposition tendency of the deposit changes, In accordance with this, it becomes possible to accurately estimate the accumulation amount.

According to an eleventh aspect of the present invention, in the fuel injection system for a direct injection internal combustion engine according to any one of the first to tenth aspects, the fuel injection control means includes means for increasing or decreasing the fuel injection amount. It is assumed that the fuel injection amounts of all cylinders or a specific cylinder after the execution of the operation are integrated, and the increase / decrease operation of the fuel injection amount is terminated based on the fact that the integrated value exceeds a predetermined value.

According to the above configuration, the period for increasing or decreasing the fuel injection amount of each fuel injection valve can be set to a length necessary and sufficient for reliably removing the deposit, and the deposit can be more reliably removed. Will be able to

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A fuel injection device according to a first embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS.

As shown in FIG. 1, an internal combustion engine 10 to which this fuel injection device is applied has six cylinders # 1 to # 6, and each of the cylinders # 1 to # 6 has a combustion chamber. 12
Fuel injection valves 14 for directly injecting fuel are provided in the inside. In the present embodiment, 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 # 1.
Cylinder # 5 → third cylinder # 3 → sixth cylinder # 6 → second cylinder # 2
→ The fourth cylinder # 4 → the first cylinder # 1 →...

Each of these fuel injection valves 14 is connected to a high-pressure pump 18 via a common delivery pipe 16. 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 by pressure. The high-pressure fuel sent to the delivery pipe 16 in this manner is distributed and supplied to each of the fuel injection valves 14, and is injected into the combustion chamber 12 from the injection holes 14a as the valves 14 open. . The fuel injection amount of the fuel injection valve 14 is set according to the fuel injection time (valve opening time of the valve 14) and the fuel injection pressure, that is, the fuel pressure in the delivery pipe 16.

The fuel injection time and fuel injection pressure of the fuel injection valve 14 are controlled by an electronic control unit 30 which performs various controls of the internal combustion engine 10. The electronic control device 30 includes a rotation speed sensor 31 for detecting an engine rotation speed, an accelerator sensor 32 for detecting a depression amount (accelerator opening) of an accelerator pedal (not shown), and a water temperature for detecting a temperature of the engine cooling water. Detection signals of various sensors, such as the sensor 33, for grasping the operation state of the engine are taken in.

The electronic control unit 30 sets a target value (target fuel pressure) for the fuel pressure in the delivery pipe 16 based on these detection signals and the like, and a fuel pressure sensor 34 provided in the delivery pipe 16. And detects the actual fuel pressure (actual fuel pressure) based on the detection signal. Further, the electronic control unit 30 performs feedback control of the amount of fuel discharged from the high-pressure pump 18 to the delivery pipe 16 so that the actual fuel pressure matches the target fuel pressure.

The electronic control unit 30 calculates a target value (target fuel injection amount) for the fuel injection amount based on the engine speed, the accelerator opening, and the like. Then, the fuel injection time is calculated based on the actual fuel pressure in the delivery pipe 16, that is, the fuel injection pressure and the target fuel injection amount, and the fuel injection valve 14 is driven to open and close based on the fuel injection time. The electronic control unit 30 calculates the target fuel injection amount based on the calculation map for calculating the fuel injection time based on the fuel injection pressure and the target fuel injection amount, the engine speed, the accelerator opening, and the like. And a memory 30a for storing various data such as a calculation map for the operation.

Further, the electronic control unit 30 controls the switching of the combustion mode of the internal combustion engine 10 between stratified combustion and homogeneous combustion by changing the fuel injection timing of the fuel injection valve 14 according to the engine operating state. Execute.

That is, when the operating state of the engine is in the low-load and low-speed range, the electronic control unit 30 sets the fuel injection timing to the latter stage of the compression stroke of each of the cylinders # 1 to # 6 in order to switch the combustion mode to stratified combustion. At the same time, the target fuel injection amount is set so that the air-fuel ratio becomes thinner than the stoichiometric air-fuel ratio. As a result, combustion is performed in a state in which a mixture having a high fuel concentration is unevenly distributed only in the vicinity of an ignition plug (not shown).

On the other hand, when the engine operating state is in the high-load high-speed range, the electronic control unit 30 sets the fuel injection timing to the intake stroke of each of the cylinders # 1 to # 6 in order to switch the combustion mode to homogeneous combustion. . As a result, the mixing time between the fuel injected from the fuel injection valve 14 and the intake air is secured, and the air-fuel mixture in the combustion chamber 12 is burned in a substantially homogeneous state in which the injected fuel and the intake air are sufficiently mixed. Become like In this homogeneous combustion, the target fuel injection amount is appropriately set according to the engine operating state so that the air-fuel ratio becomes the stoichiometric air-fuel ratio or richer or leaner than the stoichiometric air-fuel ratio.

The electronic control unit 30 performs a predetermined process for removing the deposits deposited on the injection hole portion 14a of the fuel injection valve 14 in addition to the processes relating to the fuel injection control and the switching control of the combustion mode. It is executed under conditions.

In this removing process, the electronic control unit 30
First, the integrated value of the target fuel injection amount is calculated, and the integrated value of the injected amount is compared with a predetermined determination value. Then, when the electronic control device 30 determines that the integrated value of the target fuel injection amount exceeds this determination value and it is time to remove the deposit, the electronic control device 30 temporarily increases the fuel pressure in the delivery pipe 16.

Further, the electronic control unit 30 controls the first cylinder #
The fuel injection amounts of the cylinder groups (hereinafter, referred to as “first cylinder groups”) # 1 to # 3 including the first, second cylinder # 2, and third cylinder # 3 are increased, and the other cylinders, that is, The fuel injection of the cylinder groups # 4 to # 6 including the fourth cylinder # 4, the fifth cylinder # 5, and the sixth cylinder # 6 (hereinafter, referred to as "second cylinder group") is stopped. Then, after continuing this state for a predetermined period, the electronic control unit 30 restarts the fuel injection in the second cylinder group # 4 to # 6, increases the fuel injection amount, and simultaneously executes the first cylinder group # 1 to # 1. The fuel injection of # 3 is stopped.

As described above, the fuel injection amount of the first cylinder group # 1 to # 3 is temporarily increased, so that the fuel injection amount of each of the fuel injection valves 14 of the first cylinder group # 1 to # 3 is increased. The deposits deposited in the holes 14a are removed, and the fuel injection amounts of the second cylinder groups # 4 to # 6 are temporarily increased, so that the second cylinder groups # 4 to # 6 also have the above deposits. Removal will take place.

In the present embodiment, the deposit removal processing is performed on condition that the combustion mode is set to stratified combustion. This is during stratified combustion,
The amount of intake air supplied to the combustion chamber 12 is sufficiently ensured, and even if the fuel injection amount of some of the cylinders is increased as described above, the deterioration of the exhaust characteristics and the occurrence of misfire do not occur. Because.

Hereinafter, a detailed procedure for performing such deposit removal processing will be described with reference to the flowcharts of FIGS. 2 and 3 and the timing chart of FIG. Incidentally, a series of processes shown in this flowchart is:
It is repeatedly executed with a control cycle for each predetermined crank angle synchronized with the fuel injection timing of each of the cylinders # 1 to # 6. Also,
FIG. 4 is a timing chart showing the injection amount integrated value SQINJ.
(FIG. 7A), the engine output T (FIG. 7B), and the target fuel injection amounts QINJ1 and QINJ2 in the cylinder groups # 1 to # 3 and # 4 to # 6 (FIG. 9C). , Shows an example of the temporal transition of the series of processes.

In this series of processing, first, the target fuel injection amount QINJ and the target fuel pressure PFT are read (step 100). Then, the current injection amount integrated value SQINJ
Is added to the target fuel injection amount QINJ read this time, and the added value (SQINJ + QINJ) is set as a new injection amount integrated value SQINJ (step 1).
10).

Next, it is determined whether the combustion mode is set to stratified combustion (step 115). When it is determined that the combustion mode is not set to the stratified combustion (step 115: NO), the deposit removal processing is not substantially performed, and normal fuel injection control is performed. That is, the discharge amount of the high-pressure pump 18 is feedback-controlled so that the actual fuel pressure matches the target fuel pressure PFT (step 180 in FIG. 3), and all cylinders # 1 to ##
In step 6, fuel injection is performed (step 190). Thereafter, this series of processing is temporarily ended.

On the other hand, if the combustion mode is set to stratified combustion (step 115: YES), it is next determined whether the target fuel injection amount QINJ exceeds a predetermined value Q1 (step 120). .

As described above, each cylinder group # 1 to # 3, # 4
When the fuel injection of one cylinder group among the cylinder groups # 1 to # 6 is stopped, and the fuel injection amount is increased or decreased by increasing the fuel injection amount of the other cylinder group, the cylinder groups # 1 to # 6 are made.
3, since the combustion explosion power in # 4 to # 6 becomes different, the engine output tends to fluctuate greatly. Also, the fluctuation of the engine output tends to be more remarkable when the engine load is small and the engine output is relatively small.

In step 120, it is determined whether or not the magnitude of such engine output fluctuation is within an allowable range based on the result of comparison between the target fuel injection amount QINJ and the predetermined value Q1. The predetermined value Q1 is set as a threshold value for determining whether or not the magnitude of the fluctuation of the engine output caused by the operation of increasing or decreasing the fuel injection amount is within an allowable range based on the magnitude of the engine load. I have.

Here, when it is determined that the target fuel injection amount QINJ is equal to or less than the predetermined value Q1 (step 120: N
O), that is, when it is determined that the fluctuation of the engine output caused by the above-described operation of increasing or decreasing the fuel injection amount cannot be ignored, the respective processes of the previous steps 180 and 190 are sequentially executed in order to perform normal fuel injection control. Is done.

On the other hand, when the target fuel injection amount QINJ is equal to the predetermined value Q
1 (ie, when it is determined that the magnitude of the engine output fluctuation is within the allowable range) (step 120:
YES), the injection amount integrated value SQINJ is compared with a predetermined value SQ1, and the injection amount integrated value SQINJ is compared with the predetermined value SQ1.
1 is determined (step 13).
0). This predetermined value SQ1 is used to determine that a deposit of a predetermined amount or more has been deposited in the injection hole portion 14a of each fuel injection valve 14, in other words, that the change in the injection characteristics due to the deposit deposition cannot be ignored. It is a judgment value for

Here, when it is determined that the injection amount integrated value SQINJ is equal to or less than the predetermined value SQ1 (step 13).
0: NO), there is almost no deposit accumulation, and it is determined that the change in the injection characteristics due to the deposit accumulation is negligible, and each of the above-described steps 180 and 190 is sequentially executed.

On the other hand, if it is determined that the injection amount integrated value SQINJ exceeds the predetermined value SQ1 (step 130: YES), first, the target fuel pressure PFT is set to temporarily increase the fuel injection pressure. A predetermined value ΔPFT is added to the actual fuel pressure, and the actual fuel pressure is calculated by adding this value (PFT + ΔPF
The discharge amount of the high-pressure pump 18 is feedback-controlled so as to coincide with T) (step 140).

Next, a predetermined value CLQ is further added to the predetermined value SQ1, and the added value (SQ1 + CLQ) is compared with the injection amount integrated value SQINJ (step 15).
0). If the injection amount integrated value SQINJ is equal to or smaller than the sum (SQ1 + CLQ) (step 15).
0: NO), while increasing the fuel injection amount of the first cylinder group # 1 to # 3 and stopping the fuel injection of the second cylinder group # 4 to # 6, the first cylinder group # 1 to # 3. For each of the fuel injection valves 14, the respective processes for removing the deposits accumulated in the injection hole portion 14a are executed.

That is, first, the target fuel injection amount QINJ1 in the first cylinder group # 1 to # 3 is calculated based on the following equation (1) (step 210). QINJ1 ← QINJ × 2 × K1 (1) K1: correction coefficient And the target fuel injection amount QI calculated in this manner
The fuel injection time is further calculated based on the NJ1 and the fuel injection pressure, and the first cylinder group # 1 to # 1 is calculated based on the fuel injection time.
In # 3, fuel injection is performed and the second cylinder group #
The fuel injection of 4 to # 6 is stopped (step 220).
In the present embodiment, the fuel injection times of the first cylinder groups # 1 to # 3 calculated as described above are all the cylinders # 1 to # 1.
The time is set to be longer than the fuel injection time when fuel injection is performed in # 6.

As a result of the processing in steps 210 and 220, as shown in FIG.
During a period from t1 to t2 from when INJ exceeds the predetermined value SQ1 to when the addition value (SQ1 + CLQ) is reached, execution of fuel injection by the first cylinder group # 1 to # 3 and execution of the second cylinder group # 4 to ##. The stop of the fuel injection of No. 6 is alternately repeated. Specifically, the first cylinder # 1: execution of injection → the fifth cylinder # 5: injection stop → the third cylinder # 3: execution of injection → the sixth cylinder # 6: injection stop → the second cylinder # 2: execution of injection →
Fourth cylinder # 4: Stop injection → First cylinder # 1: Execute injection →
In this manner, the fuel injection is performed every other cylinder.

In the period t1 to t2, the fuel explosion amount (target fuel injection amount QINJ1) is increased, so that the combustion explosion power in the first cylinder group # 1 to # 3 increases. The fuel injection of the second cylinder group # 4 to # 6 is stopped, and the fuel explosion power of the second cylinder group # 4 to # 6 is reduced (not generated) to be offset. Accordingly, although the engine output T slightly fluctuates as compared with the timing before the timing t1, the average value is hardly changed and is maintained at a constant value as shown by a dashed line in FIG. Become like The correction coefficient K1 in the above equation (1) is set to an appropriate value in advance based on experiments or the like so that the average value of the engine output T is kept substantially constant as described above.

In the period t1 to t2, the fuel injection pressure and the fuel injection time of each of the fuel injection valves 14 in the first cylinder group # 1 to # 3 are both increased. Are increased, and the operation time of the penetrating force is secured for a long time.
Deposits deposited on a are removed.

It should be noted that the above-mentioned predetermined value CLQ is different from the period t1-
An appropriate size is set in advance based on experiments and the like so that the deposit is reliably removed at t2. When the process of step 220 is performed, the series of processes is temporarily terminated.

On the other hand, if the injection amount integrated value SQINJ exceeds the added value (SQ1 + CLQ) in step 150 (step 150: YES), the predetermined value CLQ is further added to the added value. Is added,
The added value (SQ1 + 2CLQ) and the injection amount integrated value SQI
NJ is compared (step 160).

If the injection amount integrated value SQINJ is equal to or smaller than the added value (SQ1 + 2CLQ) (step 160: NO), the fuel injection amounts of the second cylinder groups # 4 to # 6 are increased and the first cylinder group is increased. By stopping the fuel injection of the groups # 1 to # 3, each process for removing the deposit accumulated in the injection hole portion 14a is executed for each of the fuel injection valves 14 of the second cylinder groups # 4 to # 6. Is done.

That is, similarly to the processing in step 210, the target fuel injection amount QINJ in the second cylinder group # 4 to # 6.
2 is calculated based on the following equation (2) (step 310).

QINJ2 ← QINJ × 2 × K1 (2) The target fuel injection amount QI calculated in this manner
The fuel injection time is further calculated based on the NJ2 and the fuel injection pressure, and the second cylinder group # 4 to # 4 based on the fuel injection time is calculated.
In # 6, fuel injection is performed and the first cylinder group #
The fuel injection of # 1 to # 3 is stopped (step 320).
In the present embodiment, the fuel injection times of the second cylinder groups # 4 to # 6 calculated as described above are the same for all the cylinders # 1 to # 1.
The time is set to be longer than the fuel injection time when fuel injection is performed in # 6.

As a result of the processing in steps 310 and 320, as shown in FIG. 4, after timing t2, the injection amount integrated value SQINJ is increased by the addition value (SQ1 + 2).
CLQ) during the period t2 to t3 until the second
Fuel injection by cylinder groups # 4 to # 6 and first cylinder group # 1 to #
The stop of the fuel injection of No. 3 is alternately repeated, and the fuel injection is executed every other cylinder.

In the period t2 to t3, the target fuel injection amount QINJ is increased to increase the second cylinder group # 4 to #.
Although the combustion explosion power at 6 increases, this is offset by the decrease (no generation) of the combustion explosion power at the first cylinder group # 1 to # 3. Therefore, the previous period t
As in the case of 1 to t2, the average value of the engine output T hardly changes and is kept at a constant value.

During the period t2 to t3, the deposits deposited on the injection holes 14a of the fuel injection valves 14 in the second cylinder groups # 4 to # 6 are removed. When the process of step 320 is performed, this series of processes is temporarily ended.

Thus, the cylinder groups # 1 to # 3, # 4
By performing the processing for removing the deposit in order from # 6 to # 6, the injection amount integrated value SQINJ exceeds the added value (SQ1 + 2CLQ).
If it is determined in step 60 (step 160: YE
S), the injection amount integrated value SQINJ is reset to “0” (step 170). Then, after that (after timing t3 in FIG. 4), the respective processes of the previous steps 180 and 190 are performed in order to shift from fuel injection control giving priority to deposit removal to normal fuel injection control.
That is, the temporarily increased fuel injection pressure is reduced (step 180), and fuel injection is sequentially performed again in all cylinders # 1 to # 6 (step 19).
0).

According to the fuel injection device of the present embodiment in which the fuel injection control is executed in the manner described above, the following effects can be obtained. (1) When it is determined that it is time to remove the deposit, the fuel injection of one of the cylinder groups # 1 to # 3 and # 4 to # 6 is stopped, and the other cylinder group is stopped. Fuel injection amount (target fuel injection amount QINJ1, QINJ
Since the amount of 2) is increased, the deposit accumulated on the injection hole portion 14a of the fuel injection valve 14 can be suitably removed.

Further, even if the combustion explosion power in one of the cylinder groups # 1 to # 3 and # 4 to # 6 increases due to such an increase in the fuel injection amount, this does not mean that the fuel injection is stopped. Since the combustion explosive power of the cylinder group is reduced (not generated), the combustion explosive power is offset, so that an unnecessary increase in the engine output can be suppressed as much as possible.

(2) Particularly, when increasing the fuel injection amount, both the fuel injection time and the fuel injection pressure are increased, so that the penetration force of the injected fuel is increased,
In addition, the time during which the penetrating force acts on the deposit can be secured for a long time, and a more suitable removal ability can be secured.

(3) Further, each cylinder group # 1 to # 3, # 4 to
Since the first cylinder group # 1 to # 3 and the second cylinder group # 4 to # 6 are selected so that the fuel injection timing of # 6 comes alternately, each of these cylinder groups # 1 ~ # 3, #
4 to # 6, stop fuel injection in one cylinder group,
It is possible to suppress an increase in engine output fluctuation due to a difference in the explosive combustion power between the cylinder groups # 1 to # 3 and # 4 to # 6.

(4) One of the cylinder groups # 1 to # 3 and # 4 to # 6 on condition that the target fuel injection amount QINJ reflecting the magnitude of the engine load is larger than a predetermined value Q1. Since the fuel injection of the cylinder group is stopped and the processing of increasing the fuel injection amount of the other cylinder group is performed, fluctuations in the engine output caused by performing such processing can be reduced. Become.

(5) Further, the integrated value SQINJ of the target fuel injection amount QINJ is calculated, and the timing for removing the deposit is determined on the condition that the integrated value SQINJ exceeds a predetermined value SQ1. It is possible to estimate the amount of deposit accumulated in the injection hole portion 14a of the fuel injection valve 14, and to appropriately determine the timing of the removal based on the estimation result.

(6) Each cylinder group # 1 to # 3, # 4 to
The integrated value of the target fuel injection amount QINJ (the integrated value in each of the periods t1 to t2 and t2 to t3 shown in FIG. 4) after the start of the deposit removal processing for the # 6 fuel injection valve 14 is predetermined. When the value CLQ is exceeded,
The deposit removal processing is terminated. Therefore, for example, unlike the configuration in which the deposit removal processing is terminated on the condition that a certain time has elapsed,
The execution period of the removal processing can be set to a necessary and sufficient length for reliably removing the deposit, and the deposit can be more reliably removed.

[Second Embodiment] Next, a second embodiment of the present invention will be described.
This embodiment will be described focusing on differences from the first embodiment.

In the present embodiment, the target fuel injection amount QINJ
In calculating the integrated value SQINJ, weighting is performed based on the engine operating state such as the engine cooling water temperature THW and the engine rotation speed NE, which is different from the first embodiment.

More specifically, in the present embodiment, in the process of step 110 (see FIG. 2), the injection amount integrated value SQINJ is calculated based on the following equation (3). SQINJ ← SQINJ + QINJ × KNE × KTHW (3) where “KNE” is a weighting coefficient for calculating the injection amount integrated value SQINJ by weighting the target fuel injection amount QINJ. It is set based on NE. Similarly, “KTHW” is also a weighting coefficient for calculating the injection amount integrated value SQINJ by weighting the target fuel injection amount QINJ, and this is the engine cooling water temperature THW having a correlation with the engine temperature. It is set based on.

FIG. 5 is a calculation map showing the relationship between the engine speed NE and the weighting coefficient KNE. As shown in this map, the lower the engine speed NE,
The weighting coefficient KNE is set to a large value.

Here, when the target fuel injection amount QINJ is the same, as the engine speed NE becomes relatively lower, the period from the end of fuel injection to the start of the next fuel injection becomes longer. When this period becomes longer, the injection hole 1
When the volatile components of the injected fuel adhering to 4a evaporate, the evaporating time is secured longer, so that the deposit is more likely to be deposited on the injection hole portion 14a.

For example, if the period from the end of the fuel injection to the start of the next fuel injection is short, after the fuel injection ends, the injection hole portion 14a is gradually heated by the heat in the combustion chamber 12. Even if the temperature rises and the volatile component of the attached fuel starts to evaporate, the next fuel injection is started immediately, and the injected fuel passes through the injection hole portion 14a to cool the injection hole portion 14a. Therefore, the temperature rise of the injection hole portion 14a is suppressed, and the evaporation of the volatile component is not promoted, so that the deposit is difficult to deposit.

On the other hand, if the period from the end of the fuel injection to the start of the next fuel injection becomes longer, the injection hole portion 14a tends to become hot during the period in which the fuel injection is not performed. Accordingly, the evaporation of the volatile components is promoted, and the deposit is easily deposited.

For this reason, in the present embodiment, the target fuel injection amount QINJ is weighted more heavily when the engine speed NE is lower and the deposits are more likely to accumulate in the injection hole portion 14a. Is calculated.

FIG. 6 is a calculation map showing the relationship between the engine coolant temperature THW and the weighting coefficient KTHW. As shown in this map, the engine cooling water temperature TH
The weighting coefficient KTHW is set to a larger value as W is higher. This is because the higher the engine temperature, the more the evaporation of the volatile components in the attached fuel is promoted. Therefore, even when the same amount of fuel is injected, the deposit is more likely to be deposited on the injection hole portion 14a. .

The calculation maps shown in FIG. 5 and FIG. 6 are stored as function data in the memory 30a of the electronic control unit 30, and the electronic control unit 30 calculates the target fuel injection amount through the above calculation expression (3). Each time QINJ is integrated, these maps are referred to, and a weighting coefficient K is assigned to a value corresponding to the engine speed NE and the engine coolant temperature THW at that time.
NE and KTHW are set each time.

According to the present embodiment described above, the following effects can be further obtained in addition to the effects (1) to (6) in the first embodiment. (7) Weighting coefficient KN set based on the engine operating state such as engine cooling water temperature THW and engine speed NE
Weighting is performed when calculating the integrated value SQINJ of the target fuel injection amount QINJ based on E and KTHW, so that the amount of deposition is accurately estimated in accordance with the deposition tendency of the deposit that changes according to the engine operating state. And the timing of deposit removal can be more appropriately determined.

(8) Particularly, in a situation where deposits tend to accumulate in the injection hole portion 14a, such as when the engine is running at a low speed or at a high engine temperature, the weighting coefficients KNE and KTHW are set large and the integrated value SQINJ is calculated. Because the added target fuel injection amount QINJ is weighted more, the engine speed and the engine coolant temperature TH are increased.
W, that is, the degree of evaporation of the volatile components contained in the attached fuel changes according to the engine temperature, and even if the deposition tendency of the deposit changes, it is possible to accurately estimate the amount of the deposition in accordance with this, The timing of deposit removal can be more appropriately determined.

The embodiments of the present invention have been described.
Each of these embodiments can be implemented by changing the configuration as described below. In the second embodiment, the weighting coefficient KNE set based on the engine speed NE and the engine cooling water temperature T
Although the target fuel injection amount QINJ is weighted based on both the weighting coefficient KTHW set based on the HW, these weighting coefficients KNE and KTH are used.
The weighting may be performed based on only one of W.

Also, in the second embodiment,
A weighting coefficient for weighting the target fuel injection amount QINJ as the injection amount integrated value SQINJ increases may be introduced. According to such a configuration, even when there is a tendency that the deposition of the deposit is promoted with the deposit already deposited in the injection hole portion 14a as a nucleus, the deposition amount of the deposit is appropriately estimated in accordance with such a tendency. Will be able to do it.

In the second embodiment, when integrating the target fuel injection amount QINJ, each of the weighting coefficients KN
The weighting based on E, KTHW is performed, but the period during which the deposit removal processing is being executed (after a positive determination is made in step 130 in FIG.
Only until 60 is affirmatively determined)
This weighting may be omitted.

In the above embodiments, when it is determined that it is time to remove the deposit, each of the cylinder groups # 1 to #
3, # 4 to # 6, the fuel injection of one cylinder group is stopped and the fuel injection amount of the other cylinder group is increased. For example, the fuel injection is performed for the one cylinder group. Instead of stopping, the fuel injection amount may be reduced.

In each of the above embodiments, it is determined that it is time to remove the deposit, and the fuel injection of one cylinder group is stopped and the fuel injection amount of the other cylinder group is changed from the state where all cylinders are being injected. When shifting to the state of increasing the fuel injection amount, the fuel injection amount for one cylinder group is gradually reduced and then the fuel injection is stopped, and the fuel injection amount for the other cylinder group is gradually increased to a predetermined amount. The amount may be increased up to.

More specifically, as shown in the timing chart of FIG. 7, when it is determined that it is time to remove the deposit (timing t1), from that time on, the second cylinder groups # 4 to # 6 are deactivated. , The target fuel injection amount QINJ2 is gradually reduced, and the limit amount QINJmi which may cause a misfire or the like.
At the point of time when n has been reached (timing t2), the target fuel injection amount QINJ2 is set to “0” and the fuel injection is stopped.
On the other hand, for the first cylinder groups # 1 to # 3, the target fuel injection amount QINJ1 is gradually increased, and the second cylinder groups # 4 to # 6 are increased.
When the fuel injection stop timing t2 is reached, the target fuel injection amount QINJ1 is switched to a value (QINJ × 2 × K1) obtained based on the above-mentioned equation (1).

According to such a configuration, when the fuel injection of one cylinder group is stopped and the fuel injection amount of the other cylinder group is increased from the state where all cylinders are injected, the shift is performed. As a result, even if the fluctuation of the engine output increases, the increase can be hardly felt,
Drivability can be improved.

In the above embodiments, the target fuel injection amount Q
Although INJ is integrated and the deposit removal timing is determined based on the integrated value SQINJ, this determination can be made by any method. For example, at the time of homogeneous combustion in which the air-fuel ratio is feedback-controlled so that the air-fuel ratio becomes the stoichiometric air-fuel ratio, the above-described removal timing may be determined based on the tendency of deviation between the actual air-fuel ratio and the stoichiometric air-fuel ratio. Further, the operating time of the internal combustion engine 10 and the fuel injection valve 1
In addition, the number of injections may be integrated, and the removal time may be determined based on the fact that the integrated value has reached a predetermined determination value.

In the above embodiments, the target fuel injection amount Q
The INJ is integrated each time the fuel injection timing of each of the cylinders # 1 to # 6 arrives, thereby integrating the fuel injection amounts of all the cylinders # 1 to # 6. It is also possible to representatively integrate the injection amount and determine the deposit removal time based on the integrated value.

In the above embodiments, the first cylinder group # 1 to # 1
After performing the deposit removal processing for the fuel injection valves 14 of # 3 (timing t1 to t2 in FIG. 4), the deposits for the fuel injection valves 14 of the second cylinder groups # 4 to # 6 are continuously removed. Although the removal process is performed (timing t2 to t3 in FIG. 4), for example, after performing the deposit removal process for the fuel injection valves 14 of the first cylinder groups # 1 to # 3, once all the cylinders are temporarily removed. After returning to the normal fuel injection control in which fuel injection is performed in # 1 to # 6, deposit removal processing for the fuel injection valves 14 of the second cylinder groups # 4 to # 6 may be performed.

According to such a configuration, it is possible to suppress an increase in engine output fluctuation due to continuous combustion and explosion in the cylinder in which the fuel injection amount has been increased (near timing t2 in FIG. 4).

In the above embodiments, the cylinders # 1 to # 6
Is divided into two cylinder groups, and the fuel injection valves 14 of these cylinder groups are divided into two groups.
Although the deposit removal processing for the target is sequentially performed, the deposit removal processing may be performed by dividing each of the cylinders # 1 to # 6 into, for example, three cylinder groups.
In this case, the fuel injection amount in one cylinder group may be reduced, and the fuel injection amount in the remaining two cylinder groups may be increased, or one of the remaining two cylinder groups may be used. The fuel injection amount may be increased only for the group.

In each of the above embodiments, when increasing the fuel injection amount of the fuel injection valve 14, both the fuel injection time and the fuel injection pressure are increased. However, by increasing only one of them, Alternatively, the fuel injection amount may be increased.

In each of the above embodiments, when increasing the fuel injection pressure based on the result of determination that it is time to remove the deposit, the target fuel pressure PFT, which is set based on the engine operating state, is increased by a predetermined pressure. ΔPFT is added, and the discharge amount of the high-pressure pump 18 is feedback-controlled so that the actual fuel pressure matches the sum (PFT + ΔPFT). For example, the actual fuel pressure is allowed in the fuel supply system. By increasing to the maximum pressure
The fuel injection pressure may be increased.

In the above embodiments, the cylinder groups # 1 to #
The predetermined value CLQ for judging the end timing of the deposit removal processing for 3, 3, # 4 to # 6 (timing t2, t3 in FIG. 4) is a fixed value. The relationship between the amount of deposit removal (removal capacity) is determined in advance by an experiment, and each cylinder group # 1 to # 1 is removed.
When performing the deposit removal process on # 3, # 4 to # 6, the predetermined value CLQ is variably set in accordance with the deposit removal capability based on the fuel injection pressure and fuel injection time at that time. You may make it.

In the above embodiments, the deposit removal processing is performed on condition that the combustion mode is set to the stratified combustion. For example, even in the homogeneous combustion, the air-fuel ratio becomes the stoichiometric air-fuel ratio. If the setting is leaner than the above, it is possible to perform the removal processing.

In each of the above embodiments, the internal combustion engine to which the fuel injection device is applied has been described as an example having six cylinders.
The invention can also be applied to an internal combustion engine having less than or equal to or more than seven cylinders.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a configuration of a fuel injection device for an internal combustion engine.

FIG. 2 is a flowchart showing a processing procedure when removing a deposit.

FIG. 3 is a flowchart showing a processing procedure when removing a deposit.

FIG. 4 is a timing chart showing transition of a fuel injection mode in each cylinder when deposit is removed.

FIG. 5 is a calculation map showing a relationship between an engine rotation speed and a weighting coefficient.

FIG. 6 is a calculation map showing a relationship between an engine cooling water temperature and a weighting coefficient.

FIG. 7 is a timing chart showing a transition of a fuel injection amount in each cylinder when deposit is removed.

[Explanation of symbols]

10 internal combustion engine, 12 combustion chamber, 14 fuel injection valve, 1
4a: injection hole, 16: delivery pipe, 18: high pressure pump, 20: feed pump, 22: fuel tank, 30 ...
Electronic control unit, 31: rotation speed sensor, 32: accelerator sensor, 33: water temperature sensor, 34: fuel pressure sensor, # 1 to # 1
# 6: cylinders, # 1 to # 3: first cylinder group, # 4 to # 6: second cylinder group.

Continued on the front page F-term (reference) 3G084 BA13 BA14 DA27 DA28 EA11 EB12 EB22 EC01 EC03 FA00 FA10 FA13 FA20 FA33 FA39 3G301 HA01 HA04 HA06 HA16 JA21 KA08 KA09 KA24 KA25 MA03 MA11 MA18 NA06 NA08 NC01 NC02 ND02 PB03BBZPBZPBZB08Z PE08Z PF03Z

Claims (11)

[Claims] In a fuel injection device for an in-cylinder injection type internal combustion engine that directly injects fuel into a cylinder from an injection hole portion of a fuel injection valve, it is determined that it is time to remove deposits in the injection hole portion. A fuel injection device that reduces the fuel injection amount of the fuel injection valve in some cylinders and increases the fuel injection amount of the fuel injection valve in other cylinders when it is determined that the removal timing is reached. A fuel injection device for a direct injection internal combustion engine, comprising: a control unit. 2. The cylinder according to claim 1, wherein the fuel injection control means reduces the fuel injection amount of the fuel injection valve in the one of the cylinders to "0" to stop the fuel injection of the fuel injection valve. Fuel injection device for internal injection type internal combustion engine. 3. The fuel injection control means, when increasing the fuel injection amount of a fuel injection valve in the other cylinder,
3. The fuel injection device for a direct injection internal combustion engine according to claim 1, wherein both the fuel injection time and the fuel injection pressure are increased. 4. The fuel injection control means according to claim 1, wherein the fuel injection timing of the fuel injection valves in the some cylinders and the fuel injection timing of the fuel injection valves in the other cylinders alternately arrive. The fuel injection device for a direct injection internal combustion engine according to any one of claims 1 to 3, wherein the cylinder (1) and the other cylinders are selected. 5. The cylinder injection type internal combustion engine according to claim 1, wherein the fuel injection control means performs the operation of increasing or decreasing the fuel injection amount on condition that an engine load is larger than a predetermined value. Fuel injection device. 6. The fuel injection control device according to claim 1, wherein the fuel injection control means gradually increases or decreases the fuel injection amount as time elapses from the time when the determination means determines that the removal timing has come. A fuel injection device for a direct injection internal combustion engine according to any one of the above. 7. A fuel supply system according to claim 1, wherein said determination means integrates fuel injection amounts of all cylinders or a specific cylinder, and determines the removal timing based on the fact that the integrated value exceeds a predetermined value.
The fuel injection device for a direct injection internal combustion engine according to any one of the above. 8. The fuel supply system according to claim 1, wherein said determination means weights the fuel injection amount based on a weighting coefficient set according to an engine operating state.
The fuel injection device for a direct injection internal combustion engine according to any one of the above. 9. The fuel injection device for a direct injection internal combustion engine according to claim 1, wherein said determining means sets the weighting coefficient to be larger as the engine temperature is higher. 10. The fuel injection device for a direct injection internal combustion engine according to claim 1, wherein said determining means sets the weighting coefficient to be larger as the engine rotation speed is lower. 11. The fuel injection control means accumulates the fuel injection amount of all cylinders or a specific cylinder after executing the fuel injection amount increasing / decreasing operation, based on the fact that the integrated value exceeds a predetermined value. The fuel injection device for a direct injection internal combustion engine according to any one of claims 1 to 10, wherein the operation of increasing or decreasing the fuel injection amount is terminated.