JP6519640B1 - Engine fuel control system - Google Patents

Abstract

An object of the present invention is to provide a fuel control device capable of performing appropriate fuel injection amount reduction and realizing appropriate combustion in an engine in which a purge is performed. SOLUTION: A first front-stage injection in which a fuel injection valve injects fuel in an intake stroke, a first rear-stage injection in which fuel is injected after the first front-stage injection in an intake stroke, and a second injection which injects fuel in a compression stroke If purge is performed in the operation range in which the second injection is performed, the total amount of fuel to be injected is reduced compared to the case where the purge is not performed, and the second fuel injection value of the first front injection and the first rear injection is reduced. If the fuel reduction value is made smaller and the fuel injection amount after the fuel reduction of the first front-stage injection or the first rear-stage injection becomes smaller than the minimum fuel injection amount of the fuel injection valve, the first rear-stage injection is stopped. (1) The pre-injection and the second injection are performed. [Selected figure] Figure 6

Description

  The present invention relates to a fuel control system for an engine including a fuel injection valve for injecting fuel supplied from a fuel tank into a combustion chamber of an engine body, and controlling fuel injection by the fuel injection valve. The present invention relates to fuel injection control in the case where purge for introducing vaporized fuel from an intake passage into a combustion chamber is performed.

  Conventionally, it has been practiced to introduce evaporative fuel generated in a fuel tank into a cylinder through an intake passage and burn it, thereby suppressing the evaporative fuel from being released into the atmosphere. Here, when the evaporative fuel is simply introduced into the cylinder, the evaporative fuel is added to the fuel injected from the fuel injection valve, so that the engine torque becomes larger than the required value.

On the other hand, according to Patent Document 1, when the purge in which the evaporated fuel in the fuel tank is introduced into the intake passage is performed, the injection amount of the fuel injection valve for injecting the fuel into the cylinder is An engine is disclosed that is configured to reduce in accordance with the amount of purge gas introduced into the intake passage from the tank side.
In addition, according to Patent Document 1, in order to improve the exhaust gas performance and the fuel consumption performance, a configuration in which stratified combustion is performed in an operating region where engine speed is low and engine torque is low, and when purge is performed during this stratified combustion There is disclosed a configuration for correcting the injection timing, the ignition timing and the like of the fuel injection valve.

  On the other hand, in the fuel injection valve, the fuel injection pulse width (opening time) is controlled, and a fuel injection amount substantially proportional to the fuel injection pulse width is obtained. However, when the fuel injection pulse width becomes less than the minimum fuel injection pulse width, the fuel injection amount proportional to the fuel injection pulse width can not be obtained, and there is a region where the linearity of the fuel injection amount with respect to the fuel injection pulse width is not maintained. It is known to do.

Patent No. 3846481 gazette

  As in Patent Document 1, if the amount of fuel injected into the cylinder is reduced according to the amount of purge gas while purging is being performed, the total amount of fuel supplied into the cylinder is maintained at an appropriate amount. I can do it. However, in the case where fuel injection is divided into multiple injections into a cylinder, the state of the cylinder changes depending on how much reduction is performed for each injection, so appropriate combustion may not always be realized. .

  When performing stratified combustion as in Patent Document 1, fuel is injected into the cylinder in the intake stroke, and fuel is also injected in the compression stroke, and the fuel injected in this compression stroke causes fuel concentration around the spark plug. By forming a high air-fuel mixture, stratification of the air-fuel mixture is realized. Therefore, if the amount of fuel injected in this compression stroke is greatly reduced, there is a possibility that stratification of stratified mixture and stratified combustion can not be appropriately realized.

  Therefore, when purge is performed, it is conceivable to limit the amount of decrease in fuel injection in the compression stroke and to increase the amount of decrease in fuel injection in the intake stroke. However, as described above, in the fuel injection valve, when the fuel injection pulse width is less than the minimum fuel injection pulse width, the fuel injection amount proportional to the fuel injection pulse width can not be obtained. Therefore, it is appropriate that the execution of the purge increases the fuel reduction value in the intake stroke and the fuel injection amount after the fuel reduction becomes less than the minimum fuel injection amount corresponding to the minimum fuel injection pulse width of the fuel injection valve. Because the amount of fuel injection can not be reduced, the amount of fuel in the combustion chamber and the output torque may not be maintained at appropriate values.

  An object of the present invention is to provide a fuel control system of an engine capable of performing appropriate fuel injection amount reduction when purge is performed, and capable of realizing appropriate combustion.

  According to the first aspect of the present invention, an engine body in which a cylinder is formed, an intake passage for introducing intake air into the cylinder, tumble flow generation means for generating tumble flow in the cylinder, fuel supplied from a fuel tank in the cylinder A fuel injection valve which is injected to be opposed to the tumble flow, a purge execution means capable of performing a purge which supplies evaporated fuel in the fuel tank to the intake passage, and a fuel injection control means which controls fuel injection by the fuel injection valve In the engine fuel control system, the fuel injection control means is configured to perform a first pre-injection in which the fuel injection valve injects fuel in an intake stroke and a first pre-injection in an intake stroke in a predetermined operation region set in advance. The first post-stage injection that injects fuel after the pre-stage injection and the second injection that injects the fuel in the compression stroke are performed, and when the purge is performed, the fuel injection valve The amount is reduced compared to the case where the purge is not performed, and the fuel reduction value of the second injection is made smaller than the fuel reduction value of the first front injection and the first rear injection, and the first front injection or the first rear When the fuel injection amount after the fuel reduction of the injection becomes smaller than the minimum fuel injection amount of the fuel injection valve, it is characterized in that the first post-stage injection is stopped and the first front-stage injection and the second injection are performed.

According to the above configuration, in the predetermined operation region, the first front injection and the first rear injection are performed in the intake stroke, and the second injection is performed in the compression stroke. Therefore, the fuel in the combustion chamber is stratified and stratified. Combustion can be realized and fuel consumption performance can be enhanced.
Further, it is possible to suppress the weakening of the tumble flow generated in the combustion chamber by the first front injection, and to suppress the adhesion of the fuel injected by the first rear injection to the wall surface of the cylinder by this tumble flow, and increase the soot. It can be suppressed.

  When the purge is performed, the amount of fuel injected into the combustion chamber by the fuel injection valve is reduced, so that the amount of fuel and the output torque of the combustion chamber can be maintained at appropriate values. Also, when reducing the amount of injected fuel, the fuel for the second injection performed in the compression stroke is made smaller in order to make the fuel reduction value for the second injection smaller than the fuel reduction values for the first front-stage injection and the first rear-stage injection. The injection amount can be secured to appropriately form an air-fuel mixture having a high fuel concentration in the combustion chamber, that is, the stratification of the air-fuel mixture can be appropriately performed, and more appropriate combustion can be realized.

  Further, by performing fuel reduction for each of the first front-stage injection and the first rear-stage injection, it is possible to suppress an excessive decrease in the fuel injection amount of the first front-stage injection, and the first front-stage injection is tumbled. It is possible to suppress the flow from weakening, suppress the adhesion of the fuel injected by the first rear-stage injection to the wall surface of the cylinder, and maintain the function of suppressing the increase of soot.

  When the fuel injection amount after the first front-stage injection or the first rear-stage injection fuel reduction becomes smaller than the minimum fuel injection amount of the fuel injection valve due to the reduction of the injection fuel when the purge is performed, the first rear-stage injection The first front injection and the second injection are performed by increasing the fuel injection amount of the first front-end injection so that the fuel injection amount of each injection does not fall below the minimum fuel injection amount of the fuel injection valve. By doing this, the amount of fuel in the combustion chamber and the output torque can be maintained at appropriate values.

  In addition, the fuel injection amount of the second injection performed in the compression stroke can be secured, and an air-fuel mixture having a high fuel concentration can be appropriately formed in the combustion chamber, and stratification of the air-fuel mixture can be appropriately performed. Proper combustion can be realized.

  In the second aspect of the present invention, in the first aspect of the present invention, the fuel injection control means is configured to set the fuel injection amount after the fuel reduction of the first front injection to the fuel of the first rear injection when stopping the first rear injection. It is characterized in that the first front-stage injection is carried out with a fuel injection amount obtained by adding the fuel injection amount after reduction. According to the above configuration, it is possible to secure the amount of fuel injected to the cylinder and to prevent the decrease of the output torque.

According to the invention of claim 3, in the invention of claim 1 or 2, the fuel injection control means performs the fuel reduction only for the first front-stage injection and the first rear-stage injection when the purge is executed. It is characterized.
According to the above configuration, it is possible to more appropriately form the air-fuel mixture having a high fuel concentration in the combustion chamber by the second injection performed in the compression stroke, and to realize appropriate combustion.

The invention according to claim 4 relates to the invention according to any one of claims 1 to 3, wherein, when the purge is performed, the fuel injection control means reduces the fuel reduction value of the first front injection and the fuel reduction of the first rear injection. It is characterized by equalizing the value.
According to the above configuration, it is possible to reduce the amount of fuel with respect to the first front-stage injection and the first rear-stage injection with a relatively simple structure.

  According to the invention of claim 5, in the invention according to any one of claims 1 to 4, when the predetermined operation range is in the high load range, the fuel injection control means performs the first front-stage injection and the first rear-stage injection. It is characterized in that 2 injections are carried out. According to the above configuration, stratified charge combustion can be performed in this high load region to improve fuel efficiency.

  According to the invention of claim 6, when the fuel injection control means is in the second operation area other than the predetermined operation area, the first front injection and the first rear injection are performed. Or when the first front-stage injection and the second injection are performed and the purge is performed, the fuel injection amount after the fuel reduction of the first front-stage injection or the first rear-stage injection is less than the minimum fuel injection amount The present invention is characterized in that the first front injection is performed instead of the first front injection and the first rear injection, or the first front injection and the second injection.

  According to the above configuration, when the first front injection and the first rear injection are performed in the intake stroke in the second operation region, the first front injection suppresses the weakening of the tumble flow generated in the combustion chamber. The tumble flow can suppress the adhesion of the fuel injected by the first rear-stage injection to the wall surface of the cylinder, and can suppress the increase of soot.

  Then, the fuel injection amount after the fuel reduction of the first front-stage injection or the first rear-stage injection becomes smaller than the minimum fuel injection amount of the fuel injection valve due to the reduction of the injected fuel when the purge is performed in this second operation region. In this case, the first rear-stage injection is stopped, the fuel injection amount of the first front-stage injection is increased, and the fuel injection amount of each injection is not smaller than the minimum fuel injection amount of the fuel injection valve. Since only the injection can be performed, the amount of fuel and the output torque of the combustion chamber can be maintained at appropriate values.

  Further, in the second operation region, when the first front-stage injection is performed in the intake stroke and the second injection is performed in the compression stroke, stratified combustion can be realized by stratified combustion of the fuel in the combustion chamber, and the fuel efficiency is improved. It can be enhanced. Then, if the fuel injection amount after the fuel reduction of the first front-stage injection becomes smaller than the minimum fuel injection amount of the fuel injection valve due to the reduction of the injection fuel when the purge is performed in the second operation region, (2) Stop the injection, increase the fuel injection amount of the first front-stage injection, and make only the first front-side injection implement so that the fuel injection amount of each injection does not become smaller than the minimum fuel injection amount of the fuel injection valve. As a result, the amount of fuel in the combustion chamber and the output torque can be maintained at appropriate values.

  As described above, according to the fuel control system of the engine of the present invention, it is possible to reduce the amount of fuel injection appropriately in the engine where the purge is performed, and to realize appropriate combustion.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the engine system to which the fuel control apparatus of the engine concerning embodiment of this invention was applied. It is a block diagram showing a control system of an engine system. It is the figure which showed the field of the injection pattern. It is a figure showing the injection pattern in each field, (a) is a figure in the 1st field, (b) is a figure in the 2nd low load side field, (c) is a figure in the 2nd high load side field , (D) is a diagram in the third region. It is a figure which shows the relationship between the fuel injection pulse width of an injector, and fuel injection quantity. It is the flowchart which showed the control procedure of the injector. It is the figure which showed the injection pattern in each area | region when the fuel injection quantity of injection of 1 becomes less than the minimum fuel injection quantity of an injector, (a) is a figure in the 2nd low load side area, (b) is The figure in the 2nd high load side field, (c) is a figure in the 3rd field. It is the figure which showed typically each injection quantity in each case. It is the figure which showed the air fuel ratio around the spark plug in each case. It is the figure which showed the wall surface wet amount in each case. It is the figure which showed the flow of the gas in the cylinder at the time of implementing 1st front-stage injection, and (a)-(e) is a figure in each time. It is the figure which showed the flow of the gas in the cylinder when not implementing 1st front-stage injection, and (a)-(e) is a figure in each time.

[1] Overall Configuration of Engine FIG. 1 is a view showing a configuration of an engine system according to an embodiment of the present invention and a fuel control device of the engine incorporated in the engine system.
This engine system includes a four-stroke engine body 1, an intake passage 30 for introducing combustion air (intake air) into the engine body 1, and an exhaust passage 35 for discharging exhaust gas from the engine body 1 to the outside. A fuel tank 41 for storing fuel, and a purge system (purge execution means) 40 for introducing evaporative fuel generated in the fuel tank 41 into the engine body 1 are provided. The engine system is provided in a vehicle, and the engine body 1 is used as a drive source of the vehicle. The engine main body 1 is, for example, a four-cylinder engine having four cylinders 2 aligned in a direction perpendicular to the paper surface of FIG. 1 and is a gasoline engine that mainly uses gasoline as a fuel.

  The engine body 1 has a cylinder block 3 in which a cylinder 2 is formed, a cylinder head 4 provided on the upper surface of the cylinder block 3, and a piston 11 reciprocably inserted in the cylinder 2 There is. A combustion chamber 5 is formed above the piston 11. The piston 11 is connected to the crankshaft 15 via a connecting rod, and in response to the reciprocation of the piston 11, the crankshaft 15 rotates about a central axis.

  The cylinder head 4 has an injector (fuel injection valve) 12 for injecting fuel into the combustion chamber 5 of the cylinder 2 and an ignition plug 13 for igniting the mixture of fuel and air injected from the injector 12 and air. , And each cylinder 2 is equipped with one set.

  The injector 12 has a plurality of injection holes serving as a fuel injection port at its tip, and is provided so as to face the combustion chamber 5 of each cylinder 2 from the side of the intake side thereof. In addition, the injector 12 can perform multiple injections for each fuel chamber 5 per combustion cycle. Fuel is supplied to the injector 12 from a fuel tank 41 via a pipe (not shown) and a fuel rail 14.

The spark plug 13 has a discharge electrode at its tip and is provided to face the combustion chamber 5 of each cylinder 2 from above.
The cylinder head 4 includes an intake port 6 for introducing air supplied from the intake passage 30 into the combustion chamber 5 of each cylinder 2, an intake valve 8 for opening and closing the intake port 6, and a combustion chamber 5 of each cylinder 2. An exhaust port 7 for leading the exhaust generated in the above to the exhaust passage 35 and an exhaust valve 9 for opening and closing the exhaust port 7 are provided.

  Here, the intake port 6 functions as tumble flow generation means for generating a swirl in the longitudinal direction, that is, tumble flow, in the combustion chamber 5. The injector 12 is disposed in an inclined manner so that the injection hole is directed obliquely downward, and injects the fuel supplied from the fuel tank 41 into the combustion chamber 5 so as to face the tumble flow.

  The intake passage 30 includes a plurality of (four) independent intake passages 31 (separately connecting the single intake pipe 33, the surge tank 32 of a predetermined volume, and the surge tank 32 and the intake port 6 of each cylinder 2). 1) are arranged in the direction orthogonal to the sheet of FIG.

  A throttle valve 34 a capable of opening and closing the passage of the intake pipe 33 is provided at a portion of the intake pipe 33 on the upstream side of the surge tank 32.

  The exhaust passage 35 includes four independent exhaust passages 36 communicating with the exhaust port 7 of each cylinder 2 and a single exhaust pipe extending downstream from a portion where the downstream ends of the individual exhaust passages 36 are gathered at one place. And 38. The independent exhaust passages 36 of the two cylinders 2 whose exhaust order is not continuous gather in one passage 37 respectively, and then these two passages 37 are concentrated in the exhaust pipe 38. The exhaust pipe 38 is provided with a catalyst device 90 in which a catalyst such as a three-way catalyst is incorporated.

  The purge system 40 includes a canister 42 for evaporatively adsorbing evaporated fuel evaporated in the fuel tank 41, a purge air pipe 49 for introducing air to the canister 42, and a purge pipe for connecting the canister 42 and the intake pipe 33 (purge Passage 43). The purge pipe 43 is connected to a portion of the intake pipe 33 between the throttle valve 34 a and the surge tank 32.

  The evaporated fuel adsorbed to the canister 42 is evaporated from the canister 42 by the air introduced from the purge air pipe 49. The evaporated fuel evaporated from the canister 42 is introduced into the intake pipe 33 through the purge pipe 43 together with air. Hereinafter, a gas composed of the evaporated fuel and air flowing through the purge pipe 43 is referred to as a purge gas, and the evaporated fuel contained in the purge gas is referred to as a purge fuel.

  The purge pipe 43 is provided with a purge valve 45 for opening and closing the purge pipe 43. The purge valve 45 is a DUTY control valve, repeats opening and closing, and changes the opening ratio by changing the duty ratio, which is the ratio of the opening period to the unit period including the opening period and closing period of one cycle. Be done. Hereinafter, the operation of opening the purge valve 45 and introducing the purge gas into the intake pipe 33, that is, each cylinder 2 is referred to as performing a purge.

[2] Control System The control system of the engine system will be described with reference to FIG.
This engine system is controlled by a PCM 100 (power train control module, fuel injection valve control means) mounted on a vehicle. The PCM 100 is a microprocessor configured of a CPU, a ROM, a RAM, an I / F, and the like.

  The PCM 100 includes an engine speed sensor SN1 for detecting an engine speed, an airflow sensor SN2 for detecting air introduced into the engine body 1, an accelerator opening sensor SN3 for detecting an opening degree of an accelerator pedal operated by a driver, and an intake It is electrically connected to an intake pressure sensor SN4 for detecting an intake pressure which is a pressure in the pipe 33, and a fuel pressure sensor SN5 for detecting a fuel pressure (fuel pressure) supplied to the injector 12. The PCM 100 executes various calculations based on input signals from the respective sensors (SN1 to SN5, etc.), and outputs command signals to the injector 12, the spark plug 13, the throttle valve 34, and the purge valve 45 to control them. .

Control of the injector 12 by the PCM 100 will be described next.
FIG. 3 is a diagram showing an operating range for the injection pattern. That is, in this embodiment, the number of injections (the number of injections per one combustion cycle) and the injection timing are set to be different so that the injection pattern of the injector 12 differs depending on the operating region.

  Specifically, in the third region A3 (predetermined operating region) in which the engine load is equal to or more than the second reference load T2 which is previously set in the region where the engine rotation number is equal to or less than the second reference number N2 which is preset. Three split injections are performed in which the fuel is injected in three divisions per combustion cycle. In the third region A3, as shown in FIG. 4D, the first front injection Q1A and the first rear injection Q1B are performed in this order in the intake stroke, and the second injection Q2 is performed in the compression stroke.

  On the other hand, the second region A2 (second operation region) (second operation region) in which the engine load is equal to or more than the first reference load T1 in the low rotation region where the engine rotation number is less than the first reference rotation number N1 (reference rotation number) set in advance In three regions A3), two split injections are performed in which the fuel is injected twice in one combustion cycle.

  However, in the second high load area A2b where the engine load is equal to or higher than the third reference load T3 in the second area A2, as shown in FIG. 4C, the first pre-injection Q1A (first injection) ) Is performed, and the second injection Q2 is performed in the compression stroke, and in the second low load area A2a where the engine load is less than the third reference load T3 in the second area A2, as shown in FIG. In the intake stroke, the first front injection Q1A and the first rear injection Q1B are performed in this order.

  And in other 1st area | region A1, as shown to Fig.4 (a), package injection is implemented and a fuel is injected from the injector 12 only once in 1 combustion cycle.

  Thus, performing split injection in the third area A3 and the second high load side area A2b and performing the final injection in the compression stroke performs stratified combustion in these areas A3 and A2b to improve fuel efficiency performance. It is for. That is, the fuel injected into the cylinder 2 in the intake stroke is in the vicinity of the compression top dead center and diffuses almost all over the cylinder 2 before the start of combustion, but at a timing close to the compression stroke, in particular, compression top dead center The injected fuel does not diffuse sufficiently by the start of combustion. Therefore, if the injection is performed as described above, it is possible to form an air-fuel mixture having a high fuel concentration in the vicinity of the spark plug 13 and to make the air-fuel mixture in the cylinder 2 stratified. Ignition of the mixture having a high fuel concentration can ignite the mixture and the combustion speed of the mixture can be enhanced, and the ignition timing can be advanced to improve the fuel efficiency.

Here, although split injection may be performed in the entire operation region, when the engine speed becomes high, the injector 12 has to be driven a plurality of times in a short time, and the temperature rise of the circuit for driving the injector 12 is high. It is not preferable.
Therefore, as described above, the split injection is performed only in the region where the engine speed is equal to or less than the first reference speed N1. In addition, when the engine load is low, the total amount of fuel injected to the cylinder 2 is reduced. Therefore, if split injection is performed in a region where the engine load is low, the injection amount per time may become very small, and it may not be possible to inject an appropriate amount of fuel from the injector 12. Therefore, as described above, The split injection is performed only in the region where the load is equal to or greater than the first reference load T1.

  Here, the relationship between the fuel injection pulse width and the fuel injection amount of the injector 12 according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 5, when the fuel pressure of the fuel supplied to the injector 12 is, for example, 3 MPa, the fuel injection pulse width tj (opening time) of the injector 12 is near the minimum fuel injection pulse width τmin (3 MPa) In the above, the fuel injection amount QI can be obtained linearly with respect to the fuel injection pulse width tj, but becomes non-linear if the fuel injection amount QI is less than or equal to the minimum fuel injection pulse width τmin (3 MPa).

  The region R where the fuel injection amount QI proportional to the fuel injection pulse width tj can not be obtained is a region determined by the minimum fuel injection pulse width τmin (3 MPa), and when the fuel pressure is 3 MPa, linear stability is obtained. The minimum fuel injection amount Qmin (3 MPa) to be calculated is determined corresponding to the minimum fuel injection pulse width .tau.min (3 MPa). The same tendency is observed when the fuel pressure is 2 MPa, and as shown in FIG. 5, the minimum fuel injection pulse width τ min (2 MPa) becomes smaller than the minimum fuel injection pulse width τ min (3 MPa), and the minimum fuel injection amount Qmin (2 MPa) is smaller than the minimum fuel injection amount Qmin (3 MPa).

  The PCM 100 previously stores / sets the minimum fuel injection amount Qmin of the injector 12 obtained for each fuel pressure shown in FIG. 5 (for example, 3 MPa and 2 MPa shown in FIG. 5) in the memory, and the fuel detected by the fuel pressure sensor SN5 The minimum fuel injection amount Qmin of the injector 12 corresponding to the pressure is used in the control shown in FIG.

Next, the procedure of calculating the injection amount when the purge is performed will be described using the flowchart of FIG. In the figure, reference symbol Si (I = 1, 2,...) Denotes each step.
First, in S1, the PCM 100 reads detection values of the sensors SN1 to SN5 and the like.

  Next, in S2, the PCM 100 estimates the amount of purge fuel introduced into the cylinder 2 (hereinafter simply referred to as the amount of purge fuel) Qp. The differential pressure across the purge valve 45 is calculated based on the atmospheric pressure and the value detected by the intake pressure sensor SN4, and based on the calculated differential pressure across the purge valve 45 and the opening degree of the purge valve 45 Estimate the flow rate of the introduced purge gas. The purge fuel amount Qp is estimated from the flow rate of the purge gas and the fuel concentration of the purge gas estimated separately. Here, when the purge valve 45 is fully closed and purge is not performed, the purge fuel amount Qp is set to zero.

  Next, in S3, the PCM 100 calculates the required injection amount Qr based on the operating state of the engine body 1. The required injection amount Qr is the total amount of fuel to be supplied to each cylinder 2 of the engine body 1. The PCM 100 calculates the required torque required of the engine main body 1 based on the accelerator opening degree and the vehicle speed, etc., and calculates the filling efficiency of the cylinder 2 necessary to realize the required torque, The required injection amount Qr is calculated based on the engine speed and the like.

  Next, in S4, the PCM 100 reads the minimum fuel injection amount Qmin of the injector 12 corresponding to the fuel pressure detected by the fuel pressure sensor SN5.

Next, in S5, the PCM 100 determines whether or not to carry out the batch injection, that is, whether or not the current operating range is the first range A1.
If the determination in S5 is YES, the process proceeds to S6, and the injection amount Qi of the injector 12 is set to an amount obtained by subtracting the purge fuel amount Qp from the required injection amount Qr. After S6, the process proceeds to S20, and the fuel of the injection amount Qi set in S6 is injected to the injector 12.

On the other hand, if the determination in S5 is No, the process proceeds to S7. In S7, it is determined whether or not to execute two split injections, that is, whether or not the current operating range is the second range A2.
If the determination in S7 is YES, the process proceeds to S8. In S8, it is determined whether or not the two split injections are both intake stroke injection performed in the intake stroke, that is, whether the current operating range is the second low load range A2a.

  If the determination in S8 is Yes and two split injections are to be performed, but any injection is performed in the intake stroke, the process proceeds to S9. In S9, the PCM 100 sets the injection amount Q1Ai of the first front-stage injection Q1A to a value obtained by subtracting the purge fuel amount Qp from the required injection amount Qr and dividing ratio R1 of the first front-stage injection Q1A. Further, the PCM 100 sets the injection amount Q1Bi of the first rear-stage injection Q1B to a value obtained by subtracting the purge fuel amount Qp from the required injection amount Qr and dividing ratio R2 of the first rear-stage injection Q1B. In the case of the present embodiment, R1> R2.

  Here, the division ratio is the ratio of the injection amount of each injection to the total injection amount (total amount of fuel supplied to the cylinder 2 for one combustion cycle) when performing divided injection, and the engine speed and the engine It is preset according to the load and the like.

  As described above, in the case where two split injections are carried out and when both injections are carried out in the intake stroke, the injection amounts Q1Ai and Q1Bi of the respective injections Q1A and Q1B are the purge fuel from the required injection amount Qr The amount obtained by subtracting the amount Qp is set to an amount obtained by multiplying each of the division ratios R1 and R2. The total injection amount of the injector 12 is the amount obtained by subtracting the purge fuel amount Qp from the required injection amount Qr.

  Next to S9, the process proceeds to S10, and the injection amount Q1Ai of the first front injection Q1A or the injection amount Q1Bi of the first rear injection Q1B set in S9 is less than the minimum fuel injection amount Qmin of the injector 12 read in S4. It is determined whether there is any. If the determination in S10 is No, the process proceeds to S20, and the fuel of the injection amount Q1Ai set in S9 is injected into the injector 12 in the intake stroke, and then the fuel of the injection amount Q1Bi set in S9 is injected in the intake stroke Make it jet.

  On the other hand, if the determination in S10 is Yes, the process proceeds to S6, and the injection amount Qi to be the injection amount Q1Ai of the first front-stage injection Q1A is set to an amount obtained by subtracting the purge fuel amount Qp from the required injection amount Qr. Thereafter, the process proceeds to S20, and as shown in FIG. 7A, the first rear-stage injection Q1B is stopped, and the fuel of the injection amount Q1Ai (Qi) set in step S6 is taken in the first front-stage injection Q1A. The injector 12 is made to inject at.

On the other hand, if the determination in S8 is No and the second injection of the two split injections is performed in the compression stroke, the process proceeds to S11.
In S11, the PCM 100 is a value obtained by subtracting the purge fuel amount Qp from a value obtained by multiplying the required injection amount Qr by the division ratio R1 of the first front-stage injection Q1A by the injection amount Q1Ai of the first front-stage injection Q1A (first injection). Set On the other hand, the injection amount Q2i of the second injection Q2 is set to a value obtained by multiplying the required injection amount Qr by the division ratio R2 of the second injection Q2.

  As described above, when the second split injection is performed and the second injection Q2 is performed in the compression stroke, the injection amount Q2i of the second injection Q2 is divided into the required injection amount Qr and the second injection Q2 is divided into the required injection amount Qr. The injection amount of the second injection Q2 is maintained at a value obtained by multiplying the ratio R2 and purge is not performed. Then, the injection amount is reduced only for the first front-stage injection Q1A, and the injection amount Q1Ai of the first front-stage injection Q1 is a value obtained by multiplying the required injection amount Qr by the division ratio R1 of the first front-stage injection Q1A It is set to an amount obtained by subtracting the purge fuel amount Qp from the injection amount of the first pre-injection Q1A when not being executed. The total injection amount of the injector 12 is the amount obtained by subtracting the purge fuel amount Qp from the required injection amount Qr.

  Next to S11, the process proceeds to S12, in which it is determined whether the injection amount Q1Ai of the first pre-injection Q1A set in S11 is less than the minimum fuel injection amount Qmin of the injector 12 read in S4. If the determination in S12 is No, the process proceeds to S20, and the fuel of the injection amount Q1Ai set in S11 is injected into the injector 12 in the intake stroke, and then the fuel of the injection amount Q2i set in S11 is injected in the compression stroke Make it jet.

  On the other hand, if the determination in S12 is Yes, the process proceeds to S6, and the injection amount Qi to be the injection amount Q1Ai of the first front-stage injection Q1A is set to an amount obtained by subtracting the purge fuel amount Qp from the required injection amount Qr. Thereafter, the process proceeds to S20, and as shown in FIG. 7B, the second injection Q2 is stopped, and the fuel of the injection amount Q1Ai (Qi) set in step S6 is injected in the first stroke Q1A. Make it jet to 12.

  On the other hand, if the determination in S7 is No and neither batch injection nor split injection is to be performed, that is, three split injection is performed, and the current operation range is the third range A3, the process proceeds to S13. move on.

  In S13, the PCM 100 sets the injection amount Q1Ai of the first front-stage injection Q1A to a value obtained by multiplying the required injection amount Qr by the division ratio R1A of the first front-stage injection Q1A minus the half amount of the purge fuel amount Qp. Do. Further, the injection amount Q1Bi of the first rear-stage injection Q1B is set to an amount obtained by subtracting a half amount of the purge fuel amount Qp from a value obtained by multiplying the required injection amount Qr by the division ratio R1B of the first rear-stage injection Q1B. On the other hand, the injection amount Q2i of the second injection Q2 is set to a value obtained by multiplying the required injection amount Qr by the division ratio R2 of the second injection Q2.

  Thus, when three split injections are performed in which two injections are performed in the intake stroke and one injection is performed in the compression stroke, the injection amount Q1Ai of the first pre-injection Q1A performed in the intake stroke is a request An amount obtained by multiplying the injection amount Qr by the division ratio R1A of the first front-stage injection Q1A and subtracting a half value of the purge fuel amount Qp from the injection amount of the first front-stage injection Q1A when the purge is not performed. Set to Similarly, the injection amount Q1Bi of the first rear-stage injection Q1B performed in the intake stroke is a value obtained by multiplying the required injection amount Qr by the division ratio R1B of the first rear-stage injection Q1B, and the purge is not performed It is set to an amount obtained by subtracting a half value of the purge fuel amount Qp from the injection amount of the first stage injection Q1B. On the other hand, for the second injection Q2 performed in the compression stroke, the decrease in the injection amount is not performed, and the injection amount of the second injection Q2 when the purge is not performed is maintained. Then, the total injection amount of the injector 12 is the amount obtained by subtracting the purge fuel amount Qpg from the required injection amount Qr.

  Next to S13, the process proceeds to S14, and the injection amount Q1Ai of the first front-stage injection Q1A or the injection amount Q1Bi of the first rear-stage injection Q1B set in S13 is less than the minimum fuel injection amount Qmin of the injector 12 read in S4. It is determined whether there is any. If the determination in S14 is No, the process proceeds to S20, the fuel of the injection amount Q1Ai set in S13 is injected into the injector 12 in the intake stroke, and then the fuel of the injection amount Q1Bi set in S13 is injector in the same intake stroke Then, the fuel of the injection amount Q2i set in S13 is injected to the injector 12 in the compression stroke.

  On the other hand, if the determination in S14 is Yes, the process proceeds to S15, and the purge fuel amount Qp is calculated from the value obtained by multiplying the injection amount Q1Ai of the first front injection Q1A by the division ratio R1 of the first front injection Q1A by the required injection amount Qr. The injection amount Q2i of the second injection Q2 is set to a value obtained by multiplying the required injection amount Qr by the division ratio R2 of the second injection Q2. Also in this case, the fuel injection amount Q2i of the second injection Q2 is maintained at the injection amount of the second injection Q2 when the purge is not performed, and the total injection amount of the injector 12 is the purge fuel amount from the required injection amount Qr. It is the amount obtained by subtracting Qp.

  Thereafter, the process proceeds to S20, and as shown in FIG. 7C, the first rear-stage injection Q1B is stopped, and in the first front-stage injection Q1A, the fuel of the injection amount Q1Ai set in S15 is transferred to the injector 12 in the intake stroke. Then, the fuel of the injection amount Q2i set in S15 is injected to the injector 12 in the compression stroke.

[3] Operation and Effect As described above, at the time of purge execution, the total injection amount of the injector 12 is set to an amount obtained by subtracting the purge fuel amount Qp from the required injection amount Qr, regardless of the number of injections. Therefore, while performing purge and burning the evaporated fuel in the fuel tank 41 in the cylinder 2, the total amount of fuel supplied to the cylinder 2 can be maintained at the required injection amount Qr, and the torque of the engine main body 1 can be It can be made to request torque.

  Further, in the second high load side area A2b and the third area A3, fuel efficiency is improved by dividing fuel into the intake stroke and the compression stroke and injecting fuel into the cylinder 2 to perform stratified combustion. it can.

  Moreover, when the purge is performed during the execution of this stratified combustion, the injection amount of the second injection Q2 which is the final injection in both the two-divided injection and the three-divided injection and is implemented in the compression stroke is the purge The amount of purge fuel supplied to the cylinder 2 is reduced for the other injections while maintaining the same amount as when not being performed. Therefore, the air-fuel mixture having a high fuel concentration can be formed in the cylinder 2 by the second injection Q2, and the air-fuel mixture can be stratified to realize more appropriate stratified combustion.

  Also, in the third region A3 in which the first front-stage injection Q1A, the first rear-stage injection Q1B, and the second injection Q2 are performed, the amount of fuel injected when the purge is performed reduces the first front-stage injection Q1A or the first rear stage If the fuel injection amount after the fuel reduction of the injection Q1B is less than the minimum fuel injection amount of the injector 12, as shown in FIG. 7C, the first rear-stage injection Q1B is stopped and the first front-stage injection Q1A The first front-stage injection Q1A is performed with the fuel injection amount obtained by adding the fuel injection amount after the fuel reduction of the first rear-stage injection Q1B to the fuel injection amount after the fuel reduction of the above, and then the second injection Q2 is performed.

  Therefore, all fuel supplied to the cylinder 2 is controlled so that the fuel injection amount of each injection does not become smaller than the minimum fuel injection amount of the injector 12, that is, the injector 12 can surely inject the fuel of the set injection amount. The amount can be maintained at the required injection amount Qr, and the torque of the engine body 1 can be made the required torque. Moreover, since the injection amount of the second injection Q2 can be maintained at the same amount as when the purge is not performed, an air-fuel mixture having a high fuel concentration can be formed in the cylinder 2 by the second injection Q2, More appropriate stratified combustion can be realized by stratifiing gas.

  Also, in the second low load region A2a in which the first front-stage injection Q1A and the first rear-stage injection Q1B are performed, the amount of fuel injected when the purge is performed reduces the amount of fuel after the first front-stage injection Q1A When the injection amount or the fuel injection amount after the fuel reduction of the first rear-stage injection Q1B becomes smaller than the minimum fuel injection amount of the injector 12, as shown in FIG. 7A, the first rear-stage injection Q1B is stopped and Similarly, by performing only the first front-stage injection Q1A with the fuel injection amount obtained by adding the fuel injection amount after the fuel reduction of the first rear-stage injection Q1B to the fuel injection amount after the fuel reduction of the first front-stage injection Q1A In addition, the total amount of fuel supplied to the cylinders 2 can be maintained at the required injection amount Qr, and the torque of the engine body 1 can be made the required torque.

  Further, in the second high load side area A2b where the first front-stage injection Q1A and the second injection Q2 are performed, the fuel injection after the fuel reduction of the first front-stage injection Q1A due to the reduction of the injected fuel when the purge is performed. If the amount is less than the minimum fuel injection amount of the injector 12, as shown in FIG. 7B, the second injection Q2 is stopped and the fuel injection amount after the fuel reduction of the first front-stage injection Q1A is Similarly, the total amount of fuel supplied to the cylinder 2 is maintained at the required injection amount Qr by performing only the first front-stage injection Q1A with the fuel injection amount obtained by adding the initial fuel injection amount of the second injection Q2. The torque of the engine body 1 can be made into the required torque.

  Here, in the second high load side region A2b, the fuel injection amount after the fuel reduction of the first front-stage injection Q1A is the minimum fuel injection amount of the injector 12 due to the reduction of the injection fuel when the purge is performed. If the fuel injection amount is less than the first front injection Q1A as shown in FIG. 7D, the fuel injection amount after the first front injection Q1A is reduced to the initial fuel injection amount of the second injection Q2. The second injection Q2 can be implemented with a fuel injection amount obtained by adding the injection amount, and in this case as well, the total amount of fuel supplied to the cylinder 2 can be maintained at the required injection amount Qr. Torque can be used as the required torque.

  As described above, in the third area A3, the second low load area A2a, and the second high load area A2b, the injector 12 divides the fuel into multiple injections in the intake stroke, or in the intake stroke and the compression stroke. When a plurality of split injections are performed and the purge is performed, the total amount of fuel injected by the injector 12 is reduced compared to the case where the purge is not performed, and the fuel for any one injection of the multiple split injections. If the fuel injection amount after reduction is less than the minimum fuel injection amount of the injector 12, a plurality of injections including any one injection which is less than the minimum fuel injection amount may be combined into one injection. The total amount of fuel supplied to the cylinders 2 can be maintained at the required injection amount Qr, and the torque of the engine body 1 can be made the required torque.

By the way, in the present embodiment, in the third region A3 in which two injections are performed in the intake stroke and one injection is performed in the compression stroke, the first pre-injection Q1A performed in the intake stroke at the time of purge execution. Weight reduction is performed for both the first and second rear injections Q1B. Therefore, the increase in soot can be suppressed while maintaining appropriate stratification of the air-fuel mixture.
This will be specifically described below with reference to FIGS. 8 to 12.

  In the case where the purge is performed during the implementation of the three split injection, the present inventors differ the way of reducing the injection amount from the cases 2, 3 and 4 shown in FIG. 8 and the degree of stratification in these cases and The amount of fuel adhering to the wall was examined.

  FIG. 8 is a view schematically showing the injection amount of each injection (the first front injection Q1A, the first rear injection Q1B, and the second injection Q2) in each case. Case 1 of FIG. 8 is a case where the purge is not performed. Case 2 is a case in which the injection amounts of the injections Q1A, Q1B and Q2 are respectively reduced amounts of the purge fuel amount Qpg multiplied by the division ratios R1A, R1B and R2 from the injection amounts of the case 1 . Case 3 is the injection pattern according to the present embodiment, and the second injection Q2 is not reduced but the injection amount of the first front injection Q1A and the injection amount of the first rear injection Q1B are the same This is the case where the amount of purge fuel amount Qp is reduced by half). Case 4 is a case where the amount of reduction is performed only for the first front-stage injection Q1A, and the injection amount of the first front-side injection Q1A is an amount obtained by subtracting the purge fuel amount Qp from the injection amount of Case 1.

  FIG. 9 is a diagram showing the results of CFD analysis of the A / F (air-fuel ratio) of the air-fuel mixture around the spark plug 13 at the compression top dead center for each of the cases 1 to 4. FIG. 10 is a view showing the result of the wall surface wet amount, that is, the amount of fuel adhering to the wall surface of the cylinder 2 obtained by CFD analysis for each of the cases 1 to 4.

  As shown in FIG. 9, in the case 2, the A / F around the spark plug 13 is larger (leaner) than the case, while in the case 3 and the case 4, the A / F around the spark plug 13 is The same level as in the case 1 is maintained, and as described above, it is shown that the mixture is stratified more properly if the amount of injection of the second injection Q2 is not reduced.

However, as apparent from the comparison between Case 2 and Case 3 and Case 4 in FIG. 10, the wall surface wet amount increases when the amount of decrease in the injection amount of the first front-stage injection Q1A and the first rear-stage injection Q1B is increased. . Then, in the case 4 where the amount of decrease in the first front-stage injection Q1A is larger, the amount of wall surface wetness becomes larger than in the case 3.
This is because the tumble flow in the cylinder 2 becomes weak at the time of the first second-stage injection Q1B because the first front-stage injection Q1A decreases, and therefore the fuel injected by the first second-stage injection Q1B is likely to scatter further. it is conceivable that. This will be described in detail with reference to FIGS. 11 and 12.

11 and 12 are diagrams showing the flow of gas in the cylinder 2 in the intake stroke, and (a) to (e) of FIGS. 11 and 12 show the gas flow at different times.
11, (a) to (e) show time lapses in this order, and (a) of FIG. 11, (b) show gas flow at the timing when the first pre-injection Q1A is performed, FIG. 12 (d) shows the gas flow at the timing when the first rear-stage injection Q1B is performed.
FIG. 11 is a diagram when injection is performed twice in the intake stroke, and FIG. 12 is a diagram when front-stage injection is omitted among the two injections in FIG.
Figures 11 and 12 (a), (b), (c), (d) and (e) show BTDC 275 ° CA, BTDC 265 ° CA, BTDC 235 ° CA, BTDC 210 ° CA, and BTDC 205 ° CA, respectively. Of the

  As shown in FIGS. 11 (a) and 12 (a), the tumble flow F1 is generated in the cylinder 2 in the intake stroke. Specifically, a gas flow F1 directed downward from the intake valve 8 side (the IN side in FIGS. 11 and 12) along the wall surface of the cylinder 2 is generated.

As shown in FIG. 11B, when the first pre-injection Q1A is performed in the state where the tumble flow F1 is generated as described above, the flow F2 formed by the injection is generated in the upper part in the cylinder 2 , Temporarily inhibit the tumble flow F1 from moving downward. Therefore, as shown in FIG. 11C, when the first pre-injection Q1A is performed, a relatively strong tumble flow F1 remains in the upper part in the cylinder 2 even after the first pre-injection Q1A is finished. You will come to

Therefore, when the first front-stage injection Q1A is performed, as shown in FIG. 11D, the first rear-stage injection Q1B is performed with the relatively strong tumble flow F1 remaining.
Then, along with this, in this case, the strong tumble flow F1 suppresses the scattering of the first rear-stage injection Q1B, and as shown in FIG. 11 (e), the cylinder 2 of the fuel injected by the first rear-stage injection Q1B. Adhesion to the wall is suppressed.

  On the other hand, as shown in FIGS. 12 (b) and 12 (c), when the first pre-injection Q1A is not performed, the tumble flow F1 diffuses into the entire cylinder 2 relatively early, and the cylinder 2 The momentum of the tumble flow F1 at the upper part becomes weak. Therefore, in this case, as shown in FIG. 12 (d), the fuel injected by the first rear-stage injection Q1B scatters to a distance without being substantially impeded by the tumble flow F1, and a large amount of fuel flows to the wall surface of the cylinder 2. Will adhere to the

  As described above, when the first front-stage injection Q1A is not performed or is small, the momentum of the tumble flow in the upper portion in the cylinder 2 becomes weak when the first rear-stage injection Q1B is performed and the first rear-stage injection Q1B is injected. The amount of fuel adhering to the wall surface of the cylinder 2 will increase. Then, when the amount of adhesion of the fuel to the wall surface of the cylinder 2 is increased, the adhered fuel is not appropriately burned and the amount of soot increases.

  Therefore, as described above, if the reduction is performed for both the first pre-injection Q1A and the first post-injection Q1B performed in the intake stroke in the third region A3, the injection amount of the first pre-injection Q1A is increased more The amount of fuel adhering to the wall surface of the cylinder 2 can be reduced to suppress the increase of soot.

[4] Regarding Modifications In the above embodiment, although the case where the reduction amount of the injection amount of the second injection Q2 is not set to 0 at the time of execution of purge has not been described, the injection amount may be reduced also for the second injection Q2. Good. However, in this case, the amount of decrease of the injection amount of the second injection Q2 is made smaller than the amount of decrease in the other injections Q1 or Q1A, Q1B to be suppressed to a minute amount.

  Further, in the above embodiment, the case where the injection amounts of the first front-stage injection Q1A and the first rear-stage injection Q1B are reduced by the same amount at the time of execution of purge has been described. The amounts of fuel of different amounts may be reduced for the front injection Q1A and the first rear injection Q1B. However, if the amount of decrease of the first front-stage injection Q1A and the first rear-stage injection Q1B is made the same as in the above embodiment, the injection amount of the first front-stage injection Q1A becomes too small and fuel on the wall surface of the cylinder 2 While being able to suppress that the adhesion amount of these increases, calculation can be simplified.

  Further, in the above embodiment, the case where the first second-stage injection Q1B is performed in the intake stroke in the case where the three split injections are performed has been described, but this may be performed in the compression process.

  In this case, the injector 12 performs one injection in the intake stroke and performs two injections in the compression stroke. However, when the purge is performed, the fuel injection after the fuel reduction of the injection in the intake stroke If the amount is less than the minimum fuel injection amount of the injector 12, the injection in the intake stroke and the first or second injection performed in the compression stroke are combined into one injection and performed in the intake stroke, and one in the compression stroke. The injection (initially the second or first injection) may be performed.

  In the above embodiment, although three split injections are performed at the maximum, multiple splits of four or more split injections are performed at the maximum, and when purge is performed, the total amount of fuel injected by the injector 12 is purged In this case, the fuel reduction value is appropriately set for each injection, and the fuel injection amount after the fuel reduction of any one injection among the plurality of divided injections is equal to that of the injector 12. In the case of the minimum fuel injection amount Qmin, a plurality of injections including any one injection (a plurality of injections that are appropriately set) may be combined into one injection.

Further, in the case where three split injections are performed, and two injections (first front stage injection Q1A, first rear stage injection Q1B) are performed in the intake stroke and one injection (second injection Q2) is performed in the compression stroke In the execution of the purge, the injection amount of the first front-stage injection Q1A may not be reduced, and only the injection amount of the first rear-stage injection Q1B may be reduced.
Even in this case, a large amount of injection of the first front-stage injection Q1A is secured, so adhesion of the wall surface of the cylinder 2 of fuel can be suppressed. Further, since the injection amount of the first rear-stage injection Q1B can be suppressed to a small amount, adhesion of the fuel injected by the first rear-stage injection Q1B to the wall surface of the cylinder 2 can be further reliably suppressed.

  However, when the first rear-stage injection Q1B is performed on the more retarded side, particularly when the first rear-stage injection Q1B is performed in the compression step as described above, the first rear-stage injection Q1B is also It contributes to the formation of a rich mixture. Therefore, in such a case, it is preferable to suppress the decrease amount of the injection amount of the first rear-stage injection Q1B to a small value in order to generate the air-fuel mixture having a high fuel concentration more reliably.

1 Engine Body 2 Cylinders 5 Combustion Chamber 6 Intake Port (Tumble Flow Generation Means)
12 injector (fuel injection valve)
30 Intake passage 40 Purge system (purge execution means)
41 Fuel tank 100 PCM (power train control module, fuel injection valve control means)
Q1A 1st pre-stage injection Q1B 1st post-stage injection Q2 2nd injection

Claims (6)

An engine body in which a cylinder is formed, an intake passage for introducing intake air into the cylinder, a fuel tank for storing fuel, tumble flow generation means for generating tumble flow in the cylinder, and fuel supplied from the fuel tank for the cylinder A fuel injection valve that is injected to face the tumble flow inside, a purge execution unit that can execute purge that supplies the evaporated fuel in the fuel tank to the intake passage, and a fuel injection control that controls fuel injection by the fuel injection valve A fuel controller for an engine comprising:
The fuel injection control means
In a predetermined operation range set in advance, the fuel injection valve injects fuel in the intake stroke, first post-injection in which fuel is injected after the first pre-injection in the intake stroke, and fuel in the compression stroke And the second injection to be injected
When the purge is performed, the total amount of fuel injected by the fuel injection valve is reduced compared to the case where the purge is not performed, and the fuel for the second injection is smaller than the fuel reduction value of the first front injection and the first rear injection. Make the weight loss smaller
If the fuel injection amount after the fuel reduction of the first front injection or the first rear injection is less than the minimum fuel injection amount of the fuel injection valve, the first rear injection is stopped and the first front injection and the second injection are An engine fuel control system characterized by having it carry out. The fuel injection control means
When the first rear-stage injection is to be canceled, the first front-stage injection is performed with a fuel injection amount obtained by adding the fuel injection amount after the first rear-stage injection fuel reduction to the fuel injection amount after the first front-stage injection fuel reduction. The engine fuel control device according to claim 1, The fuel injection control means
The engine fuel control system according to claim 1 or 2, wherein when the purge is performed, the fuel reduction is performed only for the first front injection and the first rear injection. The fuel injection control means
4. The fuel reduction value of the first front-stage injection and the fuel reduction value of the first rear-stage injection are made equal to each other when the purge is executed. Engine fuel control system. The fuel injection control means
The engine fuel according to any one of claims 1 to 4, wherein the first front injection, the first rear injection, and the second injection are performed when the predetermined operation area is in a high load area. Control device. The fuel injection control means
The first front injection and the first rear injection, or the first front injection and the second injection are performed when in the second operation range other than the predetermined operation range.
When the purge is performed, if the fuel injection amount after the fuel reduction of the first front injection or the first rear injection becomes smaller than the minimum fuel injection amount, the first front injection and the first rear injection, or the first front injection The engine fuel control system according to any one of claims 1 to 5, wherein the first pre-injection is performed instead of the injection and the second injection.