JP2508636B2 - Fuel injection controller for diesel engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for a diesel engine, which performs pilot injection before main fuel injection to prevent combustion noise due to ignition delay of fuel, and more particularly, The present invention relates to a fuel injection control device for a diesel engine that employs exhaust gas recirculation control.

[Prior Art] Conventionally, as one of fuel injection control devices for a diesel engine, a small amount of fuel is injected (pilot injection) before main fuel injection to cause a diesel knock that occurs due to a fuel ignition delay. That is, there is one that reduces combustion noise. That is, in this type of device, as shown in FIG. 11 (a), a small amount of fuel is injected before the main fuel injection, and the main injection of fuel is performed when the fuel begins to burn in the combustion chamber. By doing so, the fuel supplied by the main injection is quickly ignited, the pressure fluctuation caused by the ignition delay of the fuel is suppressed, and the combustion noise is reduced. In the figure, t1, t2, and t3 represent the pilot injection start time, the fuel ignition time, and the fuel main injection start time, respectively.

[Problems to be Solved by the Invention] In recent years, in diesel engines, in order to further reduce harmful components in the exhaust gas, a part of the exhaust gas is taken out of the exhaust system and recirculated to the intake system, so that the inert gas The so-called exhaust gas recirculation control is being adopted in which the maximum combustion temperature of fuel is lowered by the heat capacity of gas and NOx in exhaust gas discharged to the outside is reduced. However, in a diesel engine that adopts the exhaust gas recirculation control, a part of the exhaust gas is recirculated to the intake system, so that the ignition of the fuel is delayed depending on the recirculation amount of the exhaust gas. Therefore, even if the fuel injection delay is prevented by the pilot injection as described above, the fuel ignition timing is changed depending on the exhaust gas recirculation amount, and the combustion noise cannot be satisfactorily prevented.

That is, as shown in FIG. 11 (b), when the exhaust gas is recirculated, the fuel ignition timing is changed from the time point t2 to the time point t2 ′ depending on the exhaust gas recirculation amount when the pilot injection is performed as in the conventional case. Therefore, the fuel from the main injection cannot be quickly ignited, and diesel knock occurs.

Therefore, the present invention provides a fuel injection control device for a diesel engine, which can prevent ignition delay of fuel satisfactorily by pilot injection and can reduce combustion noise even in a diesel engine that performs exhaust gas recirculation control. It was made for the purpose.

[Means for Solving Problems] That is, the structure of the present invention for solving the above problems is
For example, as shown in FIG. 1, an operating state detecting means M2 for detecting the operating state of the diesel engine M1 and an amount of fuel corresponding to the detected operating state are supplied at least twice for pilot injection and main injection. Fuel injection means M3 for split injection and supply to the diesel engine M1, and exhaust gas recirculation means M4 for recirculating exhaust gas in an amount corresponding to the detected operating state to the intake system of the diesel engine M1.
In the fuel injection control device for a diesel engine, the injection start timing of the pilot injection is set in response to an increase in the amount of exhaust gas recirculated to the intake system of the diesel engine M1 by the exhaust gas recirculation means M4. The fuel injection control device for a diesel engine is characterized by including a correction means M5 for increasing the time interval from the end of the pilot injection to the start timing of the main injection by advancing.

Here, the operating state detection means M2 is for detecting the operating state of the diesel engine M1, for example an accelerator sensor for detecting the accelerator operation amount corresponding to the load of the diesel engine M1, a rotation for detecting the rotational speed of the diesel engine M1. It may be composed of a speed sensor or the like.

The fuel injection means M3 is a means for injecting and supplying to the diesel engine M1 a fuel in an amount corresponding to the operating state of the diesel engine M1 in at least two times of pilot injection and main injection, and for example to a fuel injection pump. An electromagnetic control valve for spill that connects and disconnects the high pressure chamber and the low pressure chamber can be arranged. Further, instead of the electromagnetic control valve for spill, an actuator using a piezoelectric element (for example, PZT or the like) may be used to perform pilot injection and main injection. With such a configuration, there is an advantage that the response speed is improved.

Next, the exhaust gas recirculation means M4 prevents a combustion temperature of the fuel from becoming high by recirculating a part of the exhaust gas to the intake system as described above, and removes NOx etc. in the exhaust gas discharged to the outside. In order to reduce, for example, a recirculation pipe that recirculates exhaust gas is provided between the exhaust pipe and the intake pipe of the diesel engine M1,
A conventional exhaust gas recirculation control device configured to change the cross-sectional area of the recirculation pipe and change the amount of exhaust gas that circulates according to the operating state of the engine may be used as it is.

Further, the correction means M5 advances the injection start timing of the pilot injection in response to the increase in the amount of exhaust gas recirculated to the intake system of the diesel engine M1 by the exhaust gas recirculation means M4, so that the main injection is performed from the end of the pilot injection. It increases the time interval until the start time of, and can be realized by a discrete logic circuit.In recent years, however, in this type of control device, a logical operation composed of CPU, ROM, RAM and other peripheral circuit elements is used. Since a circuit is often used, it can be easily realized as one control process executed by this logical operation circuit.

[Operation and Effect of the Invention] In the fuel injection control device for a diesel engine of the present invention configured as described above, the fuel injection means M3 is responsive to the operating state of the diesel engine M1 detected by the operating state detecting means M2. Fuel is injected and supplied to the diesel engine at least twice by pilot injection and main injection, and the exhaust gas recirculation means M4 detects the operating state of the diesel engine M1 detected by the operating state detecting means M2. The amount of exhaust gas according to is recirculated to the intake system of the diesel engine M1. And the correction means M5
However, in response to the increase in the amount of exhaust gas recirculated to the intake system of the diesel engine M1 by the exhaust gas recirculation means M4, by advancing the injection start timing of the pilot injection by the fuel injection means M3, the main Increase the time interval until the start of injection.

That is, in the fuel injection control device of the diesel engine of the present invention, in the operating region where the exhaust gas recirculation amount is large and the fuel ignition is delayed, the pilot injection start timing is advanced according to the ignition delay, and the pilot injection is performed. It operates so as to lengthen the time interval from the end of to the start timing of the main injection.

Therefore, according to the present invention, even if the amount of exhaust gas recirculation increases, it is possible to suppress the ignition delay of the fuel due to the main injection, to quickly ignite the main injected fuel, and to ignite the fuel. The time can be controlled to be constant according to the operating state of the diesel engine.

Therefore, according to the present invention, it is possible to control the ignition timing of the fuel at an optimum timing corresponding to the operating state of the diesel engine without being affected by the recirculation amount of the exhaust gas,
It is possible to favorably prevent the diesel knock, and eventually the combustion noise, caused by the ignition delay of the fuel, and it is possible to prevent the thermal efficiency of the diesel engine from being lowered due to the delay of the fuel ignition timing. Further, since the exhaust gas recirculation control can be executed as it is, the exhaust characteristic is not deteriorated.

[Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing a diesel engine equipped with the fuel injection control device of the present embodiment and its peripheral devices.

In the figure, 1 is a 4-cycle diesel engine, 2
Is a distribution type fuel injection pump, and power is transmitted from the diesel engine 1 to the fuel injection pump 2 via a drive shaft 3 connected to a crankshaft of the diesel engine 1.
In the fuel injection pump 2, the drive shaft 3 is connected to a vane pump 4 which is a fuel feed pump, a pulsar 5 having a plurality of protrusions on the outer peripheral surface at equal intervals, and a coupling 6. Fuel supplied from a fuel tank (not shown) is sucked from the fuel supply port 7 by the vane type pump 4,
The fuel chamber 8 is filled. The pressure of the fuel is regulated by the regulating valve 9, and the surplus fuel is returned to the fuel tank (not shown) through the fuel return port 10. The coupling 6 is
It is connected to one end side of a plunger 12 which is integrally connected to the cam plate 11, and the other end side of the plunger 12 is a cylinder 13
It is fitted inside. Coupling 6 and plunger 12
, And the plunger 12 rotates in its axial direction,
That is, it is supported so that it can reciprocate in the directions shown by arrows A and B in FIG. The plunger 12 and the cam plate 11 are urged by a spring 14 in the direction indicated by arrow A in FIG.

A roller ring 15 is arranged between the coupling 6 and the cam plate 11. On the surface of the roller ring 15 facing the cam plate 11, a cam roller 16 is attached along the circumference centered on the rotation axis of the roller ring 15. Also, the roller ring of the cam plate 11
A projection 11a is provided on the surface facing 15. Rotational force is transmitted to the cam plate 11 via the coupling 6 by the drive shaft 3 and the cam plate 11 pressed against the roller ring 15 rotates, so that the plunger 12 rotates and the arrow A and arrow A in FIG. By reciprocating in the direction indicated by B, the fuel is distributed and pressure-fed as described later.

A block 18 is attached to a housing 17 of the fuel injection pump 2 by fitting a cylinder 13. The block
A fuel passage 19 communicating with the fuel chamber 8 on the low pressure side in the housing 17 is provided in the housing 18. This fuel passage 19
Are connected or shut off by a fuel cutoff valve 20 which is a solenoid valve. Further, a fuel control valve 21, which is an electromagnetic valve for performing pilot injection and main injection, is attached to the block 18. The fuel control valve 21 is provided with a needle valve 22, and the needle valve 22, the plunger 12 and the cylinder 13 described above form a high pressure chamber 23. The high pressure chamber 23 can communicate with a fuel introduction passage 25 between the fuel cutoff valve 20 and the high pressure chamber 23 via fuel introduction recesses 24 formed on the outer peripheral surface of the plunger 12 in correspondence with the number of cylinders. The return passage 26 of the fuel control valve 21 communicates with the fuel introduction passage 25 via a communication passage 27 in the cylinder 13. A delivery valve 28 is provided in the block 18 and can communicate with the high pressure chamber 23 via fuel supply passages 29 and fuel supply recesses 30 formed on the outer peripheral surface of the plunger 12 in correspondence with the number of cylinders. Is.

The fuel injection pump 2 configured as above operates as follows. When the drive shaft 3 rotates in synchronization with the rotation of the diesel engine 1, the vane pump 4 is driven and the fuel whose pressure is adjusted by the pressure adjusting valve 9 is supplied to the fuel chamber 8, the fuel passage 19 and the fuel introducing passage 25. It On the other hand, the plunger 12 and the cam plate 11 are synchronized with the rotation of the drive shaft 3.
Rotates. At this time, when the projection 11a of the cam plate 11 rides on the cam roller 16 of the roller ring 15, the plunger 12 shifts to the fuel compression stroke, and when the projection 11a rides on the cam roller 16 the plunger 12 shifts to the fuel suction stroke. To do.

In the intake stroke of the plunger 12, the fuel cutoff valve 20 is energized and the fuel passage 19 communicates, so that the fuel is introduced into the high pressure chamber 23 through the fuel passage 19, the fuel introduction passage 25, and the fuel introduction recess 24. On the other hand, in the compression stroke of the plunger 12, the fuel in the high pressure chamber 23 is compressed only while the fuel control valve 21 is energized and the needle valve 22 blocks the through hole 22a, and the fuel supply recess 30 and the fuel supply It is pumped to the delivery valve 28 via the passage 29. When the fuel control valve 21 is de-energized, the fuel pressure in the high pressure chamber 23 causes the needle valve 22 to move in the direction indicated by the arrow B in FIG. 2, and the high pressure chamber 23 returns to the low pressure side return passage 26. And the pumping of fuel is completed. In addition,
The delivery valve 28 of the fuel injection pump 2 is connected to the injection nozzle 32 of each cylinder of the diesel engine 1 via the fuel pipe 31.

The diesel engine 1 includes a cylinder 33, a piston 34, and a cylinder head 33b to form a main combustion chamber 35, and a sub combustion chamber 36 is connected to the main combustion chamber 35. Fuel is injected into the combustion chamber 36. Further, the intake pipe 37 of the diesel engine 1 is provided with a compressor 39 of a turbocharger 38, while the exhaust pipe 40 is provided with a turbine 41 of the turbocharger 38. In addition, the exhaust pipe 40 has a waste gate valve for adjusting the boost pressure.
42 is also provided.

Further, the diesel engine 1 has a recirculation pipe 43 that recirculates a part of the exhaust gas from the exhaust pipe 40 to an intake port 37a that communicates with the intake pipe 37, and the recirculation pipe 43 controls the amount of exhaust gas circulation. A recirculation valve (hereinafter simply referred to as EGRV) 44 is installed. The EGRV 44 has a diaphragm chamber, and the diaphragm chamber is connected to a vacuum pump 46 via a pressure control valve 45. When the pressure control valve 45 is excited at a predetermined duty ratio, the negative pressure generated by the vacuum pump 46 is regulated to a negative pressure according to the duty ratio, and the regulated negative pressure is the EGRV.
Installed in 44 diaphragm chambers. Therefore, EGRV44
Opens to an opening corresponding to the pressure difference between the negative pressure and the atmospheric pressure. Therefore, the amount of exhaust gas determined by the opening degree is
It is returned from 40 to the intake port 37a. In this way, the exhaust gas circulation amount is determined by the drive duty ratio of the pressure control valve 45. When the pressure control valve 45 is not excited, the EGRV 44 is closed by the bias of the spring arranged in the diaphragm chamber of the EGRV 44. Therefore, the circulation of exhaust gas is interrupted.

As the detector, a rotational speed sensor 50 composed of an electromagnetic pickup arranged to face the outer peripheral surface of the pulsar 5 of the fuel injection pump 2 described above, an accelerator sensor 51 composed of a potentiometer for detecting an accelerator operation amount, the diesel engine 1 An intake air temperature sensor 52 for detecting the intake air temperature provided in the intake pipe 37, and an intake port 37a communicating with the intake pipe 37
A supercharging pressure sensor 53 for detecting the supercharging pressure, a water temperature sensor 54 for detecting the cooling water temperature provided on the cylinder block 33a, and a crank angle sensor closely facing the signal disc plate provided on the crankshaft (not shown). Has 56. Detection signals from these sensors are input to an electronic control unit (hereinafter simply referred to as ECU) 60, and the ECU 60 uses the input detection signals to cut off the fuel cutoff valve 20 and the fuel control valve 21.
And the pressure control valve 45 is driven to control the diesel engine 1.

Next, the configuration of the ECU 60 will be described with reference to FIG.

The ECU 60 inputs and calculates each signal detected by each sensor described above in accordance with a control program, and performs central processing unit (hereinafter simply referred to as CPU) 60a that performs processing for controlling each valve, the control program, and Read-on memory (hereinafter simply referred to as ROM) 60b in which initial data is stored in advance, ECU60
Random access memory (hereinafter simply referred to as RA
M) 60c and backup random access memory backed up by a battery so that even if the key switch of the diesel engine 1 is turned off by the driver, various data necessary for controlling the diesel engine 1 thereafter can be stored and retained. (Hereinafter referred to as backup RAM) It is configured as a logical operation circuit centering on 60d and the like, and an input port 60f and an output port 60 via a common bus 60e.
Connected to g to input / output with external devices.

Further, the ECU 60 is provided with buffers 60h, 60i, 60j, 60k for the output signals from the accelerator sensor 51, the water temperature sensor 54, the intake air temperature sensor 52, and the supercharging pressure sensor 53 described above, and the output of each sensor described above. A multiplexer 60n that selectively outputs signals to the CPU 60a, and an A / D converter 60p that converts analog signals into digital signals, a waveform shaping circuit 60 that shapes the waveforms of the output signals of the rotation speed sensor 50, and the crank angle sensor 56.
q is also provided. Signals from these sensors are input to the CPU 60a via the input port 60f.

Further, the ECU 60 is equipped with the drive circuits 60r, 60s, 60t for the fuel cutoff valve 20, the fuel control valve 21, and the pressure control valve 45 described above, and the CPU 60
60a is each drive circuit 60r, 60s, 60 via the output port 60g.
Output a control signal to t.

The processing executed by the ECU 60 will be described below with reference to the flowcharts shown in FIGS.

First, FIG. 4 is executed repeatedly every predetermined time when the diesel engine 1 is started, and the exhaust gas recirculation amount (specifically, for recirculating exhaust gas to the intake port 37a by driving and controlling the pressure control valve 45). 6 is a flowchart showing an exhaust gas recirculation amount calculation process for calculating a drive duty ratio of the pressure control valve 45).

When this processing is started, step 100 is first executed, and the cooling water temperature TW is detected by the detection signal from the water temperature sensor 54. Then, in the following step 110, it is determined whether or not the detected cooling water temperature TW is equal to or higher than the set temperature TW1, and if the cooling temperature TW is equal to or higher than the set temperature TW1, the process proceeds to the next step 120. In step 120, in order to execute the exhaust gas recirculation control, from the map as shown in FIG. 7 in which the accelerator operation amount Vh detected by the accelerator sensor 51 and the engine rotation speed Ne detected by the rotation speed sensor 50 are used as parameters, The drive duty ratio ED of the pressure control valve 45 is calculated, and the processing of this routine is once ended. On the other hand, when it is determined that the cooling water temperature TW is lower than the set temperature TW1 in step 110, that is, when the engine temperature is low, if the exhaust gas recirculation control is executed, the fuel is not ignited and the engine cannot be operated. Therefore, the process proceeds to step 130 and the drive duty ratio ED is set to prohibit exhaust gas recirculation control.
Is set to 0 and the processing of this routine is once ended. still,
The exhaust gas recirculation amount calculated in this process, that is, the pressure control valve 45
The drive duty ratio ED is stored in the RAM 60c and used as the duty ratio of the control signal output from the output port 60g to the drive circuit 60t.

Next, as shown in FIG. 5, similarly to the exhaust gas recirculation amount calculation process, the exhaust gas recirculation amount is repeatedly executed at every predetermined time when the diesel engine 1 is started, and the fuel injection amount (specifically, according to the operating state of the diesel engine 1 (specifically, 6 is a flowchart showing a fuel injection amount calculation process for calculating a power supply time of the fuel control valve 21).

As shown in the figure, in the fuel injection amount calculation process, first, step 200 is executed, and the pilot injection is performed prior to the main fuel injection by using a map as shown in FIG. 8 in which the engine speed Ne and the accelerator operation amount Vh are used as parameters. The energization time DP of the fuel control valve 21 required to execute is calculated. Next, in step 210, as in step 200, the basic injection amount QS of the main fuel injection is calculated using a map (not shown) having the engine speed Ne and the accelerator operation amount Vh as parameters. Then, in the following step 220, a pressure correction process for correcting the basic injection amount QS according to the boost pressure detected by the boost pressure sensor 53 is performed, and the actual main injection amount Q is calculated.
When the actual main injection amount Q of fuel is calculated in this way, step
Proceeding to 230, the energization time of the fuel control valve 21 required to supply the fuel of this actual main injection amount Q to the diesel engine 1.
After calculating tn, the processing of this routine is once terminated. In calculating the energization time tn, a map or an arithmetic expression using the actual main injection amount Q and the engine speed Ne as parameters is used.

Next, FIG. 6 shows that each time the crank angle sensor 56 detects a reference position signal indicating that the piston of the diesel engine 1 is at a predetermined position before top dead center, the fuel injection of FIG. 5 is performed. 5 is a flowchart showing a fuel injection process of driving and controlling a fuel control valve 21 according to the calculation result of the amount calculation process and supplying fuel to the diesel engine 1.

When this process is started as shown in the figure, first, step 30
0 is executed, the engine speed Ne and the accelerator operation amount Vh
Is used as a parameter to calculate the reference time τps from the start of the processing of this routine until the start of pilot injection. Next, at step 310, the start timing of pilot injection and the pilot injection are executed by the process described later from the map as shown in FIG. 9 using the drive duty ratio ED of the pressure control valve 45 obtained in the exhaust gas recirculation amount calculation process as a parameter. A correction amount Δτed, which is used to correct the time interval between the main injection and the main injection, is calculated. Then, in the following step 320, the above step 3
By subtracting the correction amount Δτed obtained in step 310 from the reference time τps for starting pilot injection obtained in 00, the real time τp until starting pilot injection is obtained, and the process proceeds to the next step 330. In step 330, it is judged whether or not the real time τp obtained in step 320 has elapsed after the processing of this routine was started, and this step 330 is repeatedly executed until the real time τp has elapsed.

Next, when it is determined in step 330 that the real time τp has elapsed, the following step 340 is executed to drive the fuel control valve 21 to start the pilot injection of fuel. In the next step 350, it is determined whether or not the energization time DP of the fuel control valve 21 obtained in the fuel injection amount calculation process has elapsed, and step 350 is repeatedly executed until the energization time DP elapses. When it is determined in step 350 that the time DP has elapsed, the next step 360 is executed to stop energization of the fuel control valve 21 and stop the pilot injection of fuel. That is, in the processing from step 340 to step 360, the fuel control valve 21 is set according to the energization time obtained in the fuel injection amount calculation processing.
By energizing, the fuel pilot injection is executed.

When the pilot injection of fuel is thus executed, step 370 is executed this time, and the reference time τs from the end of pilot injection to the start of main fuel injection is calculated using the engine speed Ne and the accelerator operation amount Vn as parameters. To be done. Then, in subsequent step 380, by adding the correction amount Δτed obtained in step 310 to the calculated reference time τs, the real time τ from the end of pilot injection to the start of fuel main injection is set to the exhaust gas recirculation amount ED. According to the above, the process proceeds to the next step 390. In step 390, it is determined whether or not the real time τ obtained in step 380 has elapsed after the completion of pilot injection, and this step 390 is repeatedly executed until the real time τ has elapsed.

Next, when it is determined in step 390 above that the real time τ has elapsed, the following step 400 is executed, and this time the fuel control valve 2
Drive 1 to start the main injection of fuel. Then, in step 410, it is determined whether or not the energization time tn of the fuel control valve 21 obtained in the fuel injection amount calculation process has elapsed, and step 410 is repeatedly executed until the energization time tn elapses. After that, when it is determined in step 410 that the time tn has elapsed, the next step 420 is executed to stop the energization of the fuel control valve 21 and stop the main fuel injection. That is, in steps 400 to 420, the main injection of fuel is performed by energizing the fuel control valve 21 according to the energization time tn obtained in the fuel injection amount calculation process, as in the processes of steps 340 to 360 above. It is running. When the main fuel injection is stopped in step 420, the processing of this routine is once terminated.

In the diesel engine 1 of the present embodiment configured and controlled as described above, as shown in FIG. 10, after the reference position signal is detected by the crank angle sensor 56, it is obtained in step 320 of the fuel injection process. At time T1 when the real time τp has elapsed, the drive signal of the fuel control valve 21 is turned on and the pilot injection is started. This pilot injection is terminated by turning off the drive signal at time T2 when the time DP obtained in step 200 of the fuel injection amount calculation process has elapsed, and then the actual time τ obtained in step 380 of the fuel injection control elapses. During this period, fuel injection is stopped. Then, the time T3 when the real time τ has elapsed from the time T2 when the pilot injection was stopped
Then, the drive signal of the fuel control valve 21 is turned on again, and the main injection of fuel is started this time. This fuel main injection is performed at time T when the time tn obtained in step 230 of the fuel injection amount calculation process has elapsed.
It is ended by turning off the drive signal in 4, and the fuel injection is completed.

By the way, it is desirable that the fuel supplied by the pilot injection is ignited at least before the main fuel injection, so that the fuel by the main fuel injection spreads simultaneously with the main injection without ignition delay, and the fuel noise can be reduced. However, conventionally, in the device in which the exhaust gas recirculation control is executed as in the present embodiment, the ignitability of the fuel is deteriorated due to the exhaust gas recirculation amount as described above, and the fuel by the pilot injection injection is Sometimes it didn't ignite before. However, in the present embodiment, the energization start time T1 of the fuel control valve 21 for starting the pilot injection is set by the correction amount Δτed obtained according to the drive duty ratio ED of the pressure control valve 45 (that is, the exhaust gas recirculation amount). The time τ from the time T2 to the time T3 at which the main fuel injection is started after the end of the pilot injection is increased according to the correction amount Δτed, so that the fuel injected by the pilot injection is changed at the time T5 before the main fuel injection. It becomes possible to ignite, and it becomes possible to quickly ignite the fuel by the main injection.

That is, as shown in FIG. 11 (c), the start of pilot injection is advanced from the conventional time t1 to time t1 ′ by the correction amount Δτed according to the exhaust gas recirculation amount, and then the time when main injection is started.
By increasing the time until t3 by the correction amount Δτed according to the exhaust gas recirculation amount, the fuel by pilot injection can be ignited at the same time t2 as when the exhaust gas recirculation control is not executed, and the exhaust gas recirculation Even in the diesel engine in which the control is executed, the fuel ignition delay due to the main injection can be prevented, and the combustion noise caused by the fuel ignition delay can be satisfactorily reduced.

And, in particular, in this embodiment, by advancing the start timing of the pilot injection in accordance with the increase of the exhaust gas recirculation amount,
Since the time interval from pilot injection to main injection is changed according to the exhaust gas recirculation amount, the ignition timing of the fuel is prevented from being changed by the exhaust gas recirculation amount, and the ignition timing of the fuel with respect to the engine crank angle is It becomes possible to perform constant control according to the operating state of the diesel engine.
Therefore, according to this embodiment, the ignition timing of the fuel can be controlled to an optimal timing according to the operating state of the diesel engine without being affected by the exhaust gas recirculation amount, and the diesel ignition is delayed due to the ignition timing delay. It is also possible to prevent the thermal efficiency of the engine from decreasing.

[Brief description of drawings]

1 is a block diagram showing the configuration of the present invention, FIG. 2 is a system configuration diagram of an embodiment of the present invention, FIG. 3 is a block diagram showing the configuration of an electronic control unit thereof, and FIG. 4 is an electronic control unit. FIG. 5 is a flowchart showing the exhaust gas recirculation amount calculation process executed by the electronic control unit, FIG. 5 is a flowchart showing the fuel injection amount calculation process executed by the electronic control unit, and FIG. 6 is a flowchart showing the fuel injection process executed by the electronic control unit. Flow chart, 7th
FIG. 8 is a graph showing a data map used to calculate the drive duty ratio ED of the pressure control valve 45 in the exhaust gas recirculation amount calculation process, that is, the exhaust gas recirculation amount. FIG. FIG. 9 is a graph showing a data map used to calculate the energization time DP of the fuel control valve 21, FIG. 9 is a fuel injection procedure, and is a correction used to correct the pilot injection start timing or the time from pilot injection to main fuel injection. FIG. 10 is a graph showing a data map used for obtaining the amount Δτed, FIG. 10 is a timing chart showing the state of control of pilot injection and main injection, and FIG. 11 is conventional pilot injection control and pilot injection control according to the embodiment. 7 is a timing chart showing a comparison of the operations of and. M1 ... Diesel engine M2 ... Operating state detection means M3 ... Fuel injection means M4 ... Exhaust gas recirculation means M5 ... Correction means 1 ... Diesel engine 2 ... Fuel injection pump 21 ... Fuel control valve 43 ... Return pipe 44 ... Exhaust gas recirculation valve ( EGRV) 45 ... Pressure control valve 50 ... Rotation speed sensor 51 ... Accelerator sensor 60 ... Electronic control unit (ECU) 60a ... CPU

Claims (1)

(57) [Claims] Claim: What is claimed is: 1. An operating state detecting means for detecting an operating state of a diesel engine, and an amount of fuel according to the detected operating state is divided into at least two times, pilot injection and main injection, to obtain the diesel engine. A fuel injection control device for a diesel engine, comprising: a fuel injection means for injecting and supplying the exhaust gas to the diesel engine; and an exhaust gas recirculation means for recirculating exhaust gas in an amount corresponding to the detected operating state to the intake system of the diesel engine, By advancing the injection start timing of the pilot injection in response to an increase in the amount of exhaust gas recirculated to the intake system of the diesel engine by the exhaust gas recirculation means, from the end of the pilot injection to the start timing of the main injection. A fuel injection control device for a diesel engine, comprising: a correction unit that increases the time interval of.