JPH06101525A - Fuel injection amount control device for diesel engine - Google Patents

Abstract

PURPOSE:To suppress abrupt torque change of a diesel engine when switching is performed from an EGR control area to a BACS control area. CONSTITUTION:A boost control 22 is provided on a fuel injection pump 2 for compensating a fuel injection amount according to an operation pressure. An EGR passage 11 and a negative pressure operating EGR valve 12 are provided on a Diesel engine 1. An EVRV 17 is provided for controlling a negative pressure introduced to a negative pressure chamber 24 of the boost control 22 or a negative pressure chamber 12c of the EGR valve 12. VSVs 15, 27 are provided for selectively introducing negative pressure into a negative pressure chambers 24 and 12c. The EVRV 17 and VSVs 15, 27 are opened or closed according to an operation condition by means of an ECU 47. When switching is performed from an EGR control range to a BACS control range, an opening of the EVRV 17 is controlled so as to once reduce the negative pressure which is controlled by the EVRV 17 compared to the negative pressure at the termination point of the EGR control area and gradually increase it therefrom by means of the ECU 47.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine, and more particularly to a fuel injection amount control device for controlling the fuel injection amount of a diesel engine equipped with an exhaust gas recirculation device (EGR device).

[0002]

2. Description of the Related Art Conventionally, in a diesel engine, for the purpose of reducing nitrogen oxides (NOx) contained in the exhaust gas, part of the exhaust gas is recirculated to the intake system, that is, exhaust gas recirculation for performing EGR. It is known to apply devices.

Here, as a feature of the diesel engine, since the amount of intake air taken into the combustion chamber per one rotation is constant regardless of the engine load, the engine output is controlled by increasing or decreasing the fuel injection amount. .
Therefore, when the engine load is low, a relatively small amount of fuel is injected, so that the excess air ratio in the combustion chamber increases. On the other hand, when the engine has a high load, a relatively large amount of fuel is injected, so that the excess air ratio in the combustion chamber becomes small. Therefore, when EGR is performed when the engine with a small excess air ratio is under high load, the excess air ratio in the combustion chamber is further reduced, which may increase the smoke concentration in the exhaust gas. Therefore, in a diesel engine equipped with an EGR device, it is necessary to perform EGR control such that the EGR flow rate is increased when the fuel injection amount is small and the load is low, and the EGR flow rate is decreased as the fuel injection amount increases.

As a technique for performing EGR control from the above viewpoint, for example, there is an EGR device disclosed in Japanese Utility Model Laid-Open No. 62-20143. In the technique of this publication, a fuel injection pump provided with an all-speed type governor mechanism excellent in acceleration response is used. Further, this fuel injection pump is provided with a well-known altitude compensator for correcting the fuel injection amount according to the atmospheric pressure. And
The EGR flow rate is optimally controlled by utilizing the altitude compensator.

That is, in the EGR device of the above-mentioned conventional publication, E
A negative pressure actuated EGR valve for controlling the GR flow rate and one electromagnetic negative pressure control valve are provided. The negative pressure from the vacuum pump is introduced into the negative pressure control valve after the negative pressure is regulated by the constant pressure valve according to the atmospheric pressure. Then, in the negative pressure control valve, the introduced negative pressure is controlled so as to be substantially in inverse proportion to the accelerator lever opening, and the control negative pressure is output to the negative pressure chamber of the EGR valve. At the same time, a part of the output negative pressure from the negative pressure control valve is regulated to a constant negative pressure via the pressure regulating valve and then introduced into the atmospheric pressure chamber of the altitude compensator.

Therefore, when the diesel engine is operated in the lowland where the altitude above sea level is low, the negative pressure control valve is controlled as the accelerator lever opening decreases, and the control negative pressure is generated in the negative pressure chamber of the EGR valve. It is introduced and the EGR valve is opened. As a result, EGR control is performed. Further, when the EGR control is performed, a negative pressure is introduced into the atmospheric pressure chamber of the altitude compensator, and the fuel injection amount from the fuel injection pump is limited to a substantially constant value or less. Therefore, even if the accelerator lever opening changes, the fuel injection amount from the fuel injection pump does not change abruptly, and variation in the fuel injection amount with respect to the accelerator lever opening can be suppressed.

On the other hand, when the diesel engine is operated in the lowland and the accelerator lever opening is increased, the negative pressure adjusted by the negative pressure control valve becomes small, and E
The GR valve is closed and the EGR control is stopped. At this time, the pressure in the atmospheric pressure chamber of the altitude compensator becomes atmospheric pressure, and the injection amount from the fuel injection pump is controlled to a normal amount. On the other hand, when the accelerator lever opening degree increases in the high altitude above sea level, the output negative pressure from the constant pressure valve becomes zero, the EGR valve is closed, and the EGR control is stopped. Further, the pressure in the atmospheric pressure chamber of the altitude compensator becomes atmospheric pressure. And since the atmospheric pressure at high altitude is relatively low,
Due to the action of the altitude compensator, the fuel injection amount from the fuel injection pump is reduced. In this way, altitude compensation of the fuel injection amount is performed corresponding to the EGR control.

[0008]

However, in the technique of the above-mentioned prior art publication, the negative pressure applied to the atmospheric pressure chamber of the altitude compensator in the transient state in which the operation region of EGR control shifts to the altitude compensation operation region. Suddenly changes to atmospheric pressure. Therefore, at the beginning of switching to the altitude compensation operating range, the fuel injection amount from the fuel injection pump changes abruptly, causing a rapid torque change in the diesel engine,
There was a fear that the drivability would be deteriorated.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to rapidly operate a diesel engine when switching from an operating range of EGR control to an operating range of injection amount compensation control according to pressure. To provide a fuel injection amount control device for a diesel engine capable of suppressing various torque changes.

[0010]

In order to achieve the above object, in the present invention, as shown in FIG. 1, a fuel injection pump M2 for pumping fuel to a diesel engine M1.
And an injection amount compensator M4 provided in the fuel injection pump M2 for compensating the fuel injection amount from the fuel injection pump M2 according to the operating pressure introduced into the pressure chamber M3, and the exhaust gas discharged from the diesel engine M1. An exhaust gas recirculation passage M7 that connects the exhaust system M5 and the intake system M6 to recirculate a part of the exhaust gas to the intake air taken into the engine M1.
An exhaust gas recirculation control valve M9 that operates according to the negative pressure introduced into the negative pressure chamber M8 to open and close the exhaust gas recirculation passage M7, and the pressure chamber M3 and the exhaust gas of the injection amount compensation device M4. One negative pressure control valve M1 opened and closed to control the negative pressure introduced into the negative pressure chamber M8 of the gas recirculation control valve M9.
0 and the negative pressure controlled to selectively introduce the negative pressure controlled by the negative pressure control valve M10 into the pressure chamber M3 of the injection amount compensation device M4 or the negative pressure chamber M8 of the exhaust gas recirculation control valve M9. The switching valve M11, the operating state detecting means M12 for detecting the operating state of the diesel engine M1, and the negative pressure control valve M according to the detection result of the operating state detecting means M12.
First negative pressure control valve control means M13 for controlling the opening degree of 10
And a control region determination unit M14 that determines the fuel injection amount compensation control region and the exhaust gas recirculation control region based on the detection result of the operating state detection unit M12, and the determination result of the control region determination unit M14. In a fuel injection amount control device for a diesel engine, which includes a negative pressure switching valve control unit M15 that controls switching of the negative pressure switching valve M11, a control region determination unit M14 shifts from an exhaust gas recirculation control region to a fuel injection amount compensation control region. When it is determined that the negative pressure has been switched, the negative pressure controlled by the negative pressure control valve M10 is set to be once smaller than the negative pressure at the end of the exhaust gas recirculation control region and then gradually increased. Control valve M10
The second negative pressure control valve control means M16 for controlling the opening degree of is provided.

[0011]

According to the above construction, as shown in FIG. 1, the operating state detecting means M12 detects the operating state of the diesel engine M1. Then, in the first negative pressure control valve control means M13, the opening degree of the negative pressure control valve M10 is controlled according to the detection result of the operating state. Also, the control area determination means M1
At 4, it is determined whether the fuel injection amount compensation control region or the exhaust gas recirculation control region is in accordance with the detection result of the operating state. Then, according to the judgment result of the control area,
The negative pressure switching valve control means M15 controls switching of the negative pressure switching valve M11.

Here, when the determination of the control region determination means M14 is in the fuel injection amount compensation control region, the negative pressure switching valve M
The negative pressure control valve M1
Negative pressure is introduced into the pressure chamber M3 as an operating pressure according to the opening degree of 0. Then, the injection amount compensator M4 is connected to the pressure chamber M3.
It operates according to the operating pressure of. As a result, the amount of fuel to be pumped from the fuel injection pump M2 to the diesel engine M1 is compensated according to the operating pressure.

On the other hand, when the control region determining means M14 determines that the exhaust gas recirculation control region is determined, the negative pressure switching valve M1 is selected.
1 is switched and controlled, so that the negative pressure control valve M10
Negative pressure is introduced into the negative pressure chamber M8 in accordance with the opening of the exhaust gas recirculation control valve M9 to open the exhaust gas recirculation passage M7. As a result, part of the exhaust gas discharged from the diesel engine M1 to the exhaust system M5 is introduced into the intake system M6 through the exhaust gas recirculation passage M7 and is recirculated to the intake air taken into the engine M1.

Further, in the second negative pressure control valve control means M16, when the determination of the control area determination means M14 switches from the exhaust gas recirculation control area to the fuel injection amount compensation control area, the negative pressure control valve M10. The negative pressure control valve M1 is controlled so that the negative pressure controlled by is once smaller than that at the end of the exhaust gas recirculation control region and then gradually increases.
The opening degree of 0 is controlled.

Therefore, when switching to the fuel injection amount compensation control region, a large negative pressure is not introduced into the pressure chamber M3 of the injection amount compensation device M4 at once, but at the end of the exhaust gas recirculation control region. A negative pressure smaller than the negative pressure is once introduced into the pressure chamber M3 as the operating pressure, and then the negative pressure is gradually increased. Then, the injection amount compensator M4 operates in accordance with the change in the negative pressure, and the amount of fuel pumped from the fuel injection pump M2 to the diesel engine M1 is gradually changed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the fuel injection amount control device for a diesel engine according to the present invention will be described in detail below with reference to FIGS.

FIG. 2 shows a schematic configuration diagram of a diesel engine system mounted on an automobile in this embodiment. This system includes a diesel engine 1 and a fuel injection pump 2 that pumps fuel to the engine 1.

The engine body 3 constituting the diesel engine 1 is composed of a plurality of cylinders, and fuel injection nozzles (not shown) are provided corresponding to the combustion chambers of the respective cylinders. An intake manifold 4 forming an intake system and an exhaust manifold 5 forming an exhaust system are connected to the engine body 3. The intake manifold 4 has an intake passage 6
However, exhaust passages 7 are connected to the exhaust manifolds 5, respectively. A compressor 8 is provided upstream of the intake passage 6, and a turbine 9 is provided downstream of the exhaust passage 7. The compressor 8 and the turbine 9 constitute a turbocharger 10. As is well known, the turbocharger 10 rotates the turbine 9 by the exhaust gas flowing through the exhaust passage 7 and rotates the compressor 8 by the rotational force of the exhaust gas so that each combustion of the engine body 3 passes through the intake passage 6 and the intake manifold 4. The pressure of the intake air taken into the chamber is increased. That is, the engine body 3 is supercharged.

In order to recirculate a part of the exhaust gas discharged from the engine body 3 to the intake air taken into the engine body 3, that is, to perform exhaust gas recirculation (EGR), the intake passage 6 and the exhaust gas are exhausted. An EGR passage 11 that connects the both 6 and 7 is provided between the passage 7 and the passage 7. An EGR valve 12 that opens and closes the EGR passage 11 is provided in the middle of the EGR passage 11. And these E
With the GR passage 11 and the EGR valve 12, the EGR device 13
Is configured. The EGR valve 12 is a diaphragm type negative pressure operated valve. As is well known, the EGR valve 12 is
A valve body 12a for opening and closing the R passage 11, a diaphragm 12b connected to the valve body 12a, a negative pressure chamber 12c partitioned by the diaphragm 12b, and a spring 12d arranged in the negative pressure chamber 12c for urging the diaphragm 12b. And the like. When the negative pressure is not introduced into the negative pressure chamber 12c, the diaphragm 12b moves to the spring 12
The valve body 12a is urged by d to be placed at a position where the EGR passage 11 is closed. That is, the EGR valve 12 is closed. On the other hand, when the negative pressure is introduced into the negative pressure chamber 12c, the diaphragm 12b is pulled and displaced by the negative pressure, and the valve body 12a is arranged at a position where the EGR passage 11 is opened. That is, the EGR valve 12 is opened.

The negative pressure chamber 12c of the EGR valve 12 is connected through a negative pressure passage 14 to a first vacuum switching valve (first VSV) 15 which constitutes a negative pressure switching valve. The first VSV 15 is a three-system solenoid valve having an input port, an output port and an atmosphere port, and one end of the negative pressure passage 14 is connected to the output port.
Further, the input port of the first VSV 15 is connected to the output port of an electric vacuum regulating valve (EVRV) 17 as a negative pressure control valve through a negative pressure passage 16. A known vacuum damper 18 is provided in the middle of the negative pressure passage 16. E
The VRV 17 is a solenoid valve whose opening is adjusted by duty control, and its input port is connected through a negative pressure passage 19 to a vacuum pump 20 which is a negative pressure source. The vacuum pump 20 is drivingly connected to the crankshaft of the engine body 3, and is driven in conjunction with the operation of the engine body 3 to supply a negative pressure to the EVRV 17.

When the first VSV 15 is turned on, the negative pressure chamber 12c of the EGR valve 12 is moved to the negative pressure passage 1
4, through the first VSV 15 and the negative pressure passage 16, etc.,
It is connected to the output port of VRV17. At this time, the negative pressure supplied from the vacuum pump 20 to the EVRV 17 is the negative pressure passage 1 by opening the EVRV 17.
6, through the first VSV 15 and the negative pressure passage 14, etc.
It is supplied to the negative pressure chamber 12c of the R valve 12. Further, the vibration of the negative pressure supplied to the negative pressure chamber 12c at this time is smoothed by the action of the vacuum damper 18. On the other hand, when the first VSV 15 is turned off, the negative pressure chamber 12c of the EGR valve 12 is opened to the atmosphere through the negative pressure passage 14.

In addition, the engine body 3 is provided with a water temperature sensor 41 for detecting the temperature (cooling water temperature) THW of the cooling water. The fuel injection pump 2 is a distribution type and is drivingly connected to a crankshaft of the engine body 3. As is well known, a drive shaft is provided inside the fuel injection pump 2, and the drive shaft is connected to the plunger via a cam mechanism. And
When the drive shaft of the fuel injection pump 2 is rotated in conjunction with the crank shaft, the plunger is reciprocated by the same number as the number of cylinders of the engine body 3 to discharge fuel during one rotation of the drive shaft. Fuel is pumped to the fuel injection nozzle for each cylinder.

The fuel injection pump 2 has an accelerator lever 2 which is rotated in association with the operation of an accelerator pedal (not shown).
1 is provided. The accelerator lever 21 is connected to a spill ring (not shown) on the plunger. Then, by appropriately changing the rotational position of the accelerator lever 21, that is, the accelerator lever opening ACCP, the position of the spill ring is changed and the effective stroke of the plunger is changed, so that the maximum fuel injection from the fuel injection pump 2 is changed. The amount is controlled.

A lever sensor 42, which is a rotary position sensor for detecting the accelerator lever opening ACCP, is provided near the accelerator lever 21. Further, the fuel injection pump 2 is provided with a rotation speed sensor 43 for detecting the rotation speed of the crankshaft of the engine body 3, that is, the engine rotation speed NE from the rotation of the drive shaft thereof.

The fuel injection pump 2 is provided with a boost altitude compensation stopper (BACS) which constitutes an injection amount compensator for controlling the maximum injection amount according to the boost pressure PiM in the engine body 3. ,
Hereinafter, simply referred to as "boocon") 22 is provided.
As is well known, this boocon 22 has a diaphragm 22a.
It is equipped with two rooms that are divided into upper and lower parts.
Further, the diaphragm 22a has a stopper rod 22b.
Has one end fixed, and the rod 22b is connected to the spill ring described above via a governor mechanism (not shown). Here, the upper chamber partitioned by the diaphragm 22a is a supercharging pressure chamber 23 into which supercharging pressure is introduced, and the lower chamber is a negative pressure chamber 24 as a pressure chamber into which negative pressure is introduced. Has become. Then, the diaphragm 22a is displaced by the relationship between the pressure in the supercharging pressure chamber 23 and the pressure in the negative pressure chamber 24. Therefore, the vertical movement of the stopper rod 22b determined by the displacement of the diaphragm 22a regulates the movement of the spill ring in the fuel increasing direction.
The maximum injection amount from the fuel injection pump 2 is determined.

The boost pressure chamber 23 of the boocon 22 communicates with the intake passage 6 through the boost pressure passage 25. As a result, the supercharging pressure supercharged by the compressor 8 is introduced into the supercharging pressure passage 25. Further, the negative pressure chamber 24 of the boocon 22 is connected to a second VSV 27 which constitutes a negative pressure switching valve through a negative pressure passage 26. Second VSV27
Is a three-way solenoid valve having an input port, an output port and an atmospheric port, and the negative pressure passage 2 is provided at the output port.
One end of 6 is connected. The input port of the second VSV 27 is connected to the output port of the EVRV 17 through the negative pressure passage 28.

When the second VSV 27 is turned on, the negative pressure chamber 24 of the boocon 22 is moved to the negative pressure passage 26,
Through the second VSV 27 and the negative pressure passage 28, the EVRV
It is connected to 17 output ports. At this time, the negative pressure supplied from the vacuum pump 20 to the EVRV 17 is EV
When the RV 17 is opened, it is supplied to the negative pressure chamber 24 of the boocon 22 through the negative pressure passage 28, the second VSV 27 and the negative pressure passage 26. On the other hand, when the second VSV 27 is turned off, the negative pressure chamber 24 of the boocon 22 becomes
It is opened to the atmosphere through the negative pressure passage 26.

In this embodiment, the boost pressure passage 25 described above is used.
An intake pressure sensor 44 is provided in order to detect the supercharging pressure PiM in (1) and the control negative pressure CNP in the negative pressure passage 16. In order to selectively detect the supercharging pressure PiM and the control negative pressure CNP by the intake pressure sensor 44, the third V
SV29 is provided. The third VSV 29 is a three-way solenoid valve having two input ports and one output port, one input port is connected to the supercharging pressure passage 25 through the communication passage 30, and the other input port is Communication passage 3
1 to the negative pressure passage 16. The remaining output ports are connected to the intake pressure sensor 44 through the communication passage 32.

When the third VSV 29 is turned on, the intake pressure sensor 44 causes the communication passage 32, the third VS.
It communicates with the supercharging pressure passage 25 through the V 29 and the communication passage 30. As a result, the intake pressure sensor 44 detects the supercharging pressure PiM applied to the supercharging pressure passage 25. Further, the intake pressure sensor 44 is turned off by turning off the third VSV 29.
Is communicated with the negative pressure passage 16 through the communication passage 32, the third VSV 29, and the communication passage 31. As a result, the intake pressure sensor 44 detects the control negative pressure CNP applied to the negative pressure passage 16.

In this embodiment, as the operating state detecting means of the diesel engine 1, the water temperature sensor 41, the lever sensor 42, the rotation speed sensor 43 and the intake pressure sensor 44 are used.
Etc. are provided. In addition, a vehicle speed sensor 45 for detecting the traveling speed (vehicle speed) SPD of the automobile is provided. The vehicle speed sensor 45 is provided in an automatic transmission (not shown), and the vehicle speed S is determined by the rotation of the gears of the automatic transmission.
It is designed to detect PD. Further, the automatic transmission is provided with a shift position sensor 46 which outputs a signal instructing the shift position ShP.

In this embodiment, the EVR described above is used.
Each of the V17 and the VSVs 15, 27, 29 is drive-controlled by an electronic control unit (hereinafter simply referred to as "ECU") 47. In this example, the EC
U47 constitutes first and second negative pressure control valve control means, control region determination means, and negative pressure switching valve control means. The ECU 47 includes a central processing unit (CPU), various memories that pre-store a predetermined control program and the like and a primary storage of the calculation result of the CPU, and these units, an external input circuit, an external output circuit, and the like. It is configured as a logical operation circuit connected by. And ECU4
The external input circuit 7 includes a water temperature sensor 41, a lever sensor 42, a rotation speed sensor 43, an intake pressure sensor 44,
The vehicle speed sensor 45, the shift position sensor 46, etc. are connected to each other. Also, the external output circuit of the ECU 47
The above-mentioned EVRV 17 and each VSV 15, 27, 29, etc. are respectively connected. Since the detailed electrical configuration of the ECU 47 is well known, its description is omitted here.

Next, the content of the processing operation of the fuel injection amount control executed by the ECU 47 in the fuel injection amount control device configured as described above will be described. Figure 3 is E
It is a flowchart explaining the "EGR / BACS control routine" executed by the CU 47, which is executed at predetermined time intervals.

When the processing shifts to this routine, first in step 101, the cooling water temperature THW and the accelerator lever opening A are calculated based on the signals from the various sensors 41 to 46.
CCP, engine speed NE, supercharging pressure PiM, control negative pressure CNP, vehicle speed SPD, and shift position ShP are read.

Next, at step 102, the region of the present operating state is calculated based on the accelerator lever opening ACCP and the engine speed NE which have been read this time.
That is, based on the accelerator lever opening ACCP and the engine speed NE, it is determined whether the current operating range is the “BACS control range” in which the maximum injection amount should be controlled by the boocon 22. Also, it is calculated whether the "EGR control region" in which the EGR flow rate should be controlled by the EGR device 13 or the "non-EGR control region" in which the EGR flow rate is not controlled. This calculation is performed as shown in FIG.
It is carried out by referring to a map which is predetermined by the relationship between E and the accelerator lever opening ACCP and stored in the memory.

Then, in step 103, it is judged whether or not the result of the area calculation is "non-EGR control area". Here, when the result of the area calculation is the "non-EGR control area", the process proceeds to step 200, and learning control of the atmospheric pressure PA is executed.

That is, the second VSV 27 and the third VSV 2
9 and 9 are turned off, and the first VSV 15 is turned on. Further, the EVRV 17 is fully closed to make its output negative pressure zero (atmospheric pressure PA). As a result, the intake pressure sensor 44
The atmospheric pressure PA acts through the EVRV 17, the communication passage 31, the third VSV 29 and the communication passage 32, and the intake pressure sensor 44 detects the atmospheric pressure PA. Then, in the ECU 47, the detected atmospheric pressure P
The size of A is learning-controlled. Here, detailed description of the processing content for the learning control of the atmospheric pressure PA will be omitted. Then, after the processing of step 200 is completed, the subsequent processing is once completed.

On the other hand, in step 103, when the result of the area calculation is not the "non-EGR control area", the process proceeds to step 104 and it is determined whether the result of the area calculation is the "EGR control area". . Here, if the result of the area calculation is the “EGR control area”, step 300
Then, the normal EGR control is executed.

That is, the second VSV 27 and the third VSV 2
9 and 9 are turned off, and the first VSV 15 is turned on. Further, the opening degree of the EVRV 17 is duty controlled. As a result, in the EVRV 17, the negative pressure from the vacuum pump 20 is adjusted and output as the control negative pressure CNP. Then, the control negative pressure CNP passes through the negative pressure passage 16, the first VSV 15 and the negative pressure passage 14 and then the EGR valve 1
2 is introduced into the negative pressure chamber 12c, and the EGR valve 12 is opened with an opening degree according to the magnitude of the control negative pressure CNP. That is, E
The EGR flow rate flowing through the GR passage 11 is controlled. At this time, the intake pressure sensor 44 passes through the communication passage 31, the third VSV 29, and the communication passage 32 through the control negative pressure CN.
Since P acts, the intake pressure sensor 44 detects the control negative pressure CNP. Then, in the ECU 47,
Based on the detected control negative pressure CNP, EVRV17
The duty control of the opening of is feedback-controlled.
Here, detailed description of the processing contents of the EGR control is omitted. Then, after finishing the process of step 300,
The subsequent processing is once ended.

On the other hand, in step 104, when the result of the area calculation is not the "EGR control area", "BAC"
Assuming that it is the “S control area”, the process proceeds to step 105. Then, in step 105, the second VS
V27 and the third VSV29 are turned on, and the first V
The SV15 is turned off. As a result, EVRV17
Is connected to the negative pressure chamber 24 of the boocon 22 through the negative pressure passage 28, the second VSV 27 and the negative pressure passage 26. In addition, the intake pressure sensor 44 includes a supercharging pressure passage 2
5, the supercharging pressure PiM acts through the communicating passage 30, the third VSV 29, and the communicating passage 32, and the intake pressure sensor 44 detects the supercharging pressure PiM.

Next, at step 106, a negative pressure required value GBACSP for determining the control negative pressure CNP to be introduced into the negative pressure chamber 24 of the boocon 22 is calculated. This calculation is performed based on the accelerator lever opening ACCP, the engine speed NE, and the supercharging pressure PiM that are read this time. In addition, as shown in FIG. 5, this calculation is performed by referring to a map in which the negative pressure request value GBACSP is predetermined from the relationship between the accelerator lever opening ACCP and the supercharging pressure PiM and stored in the memory. . Also, the negative pressure required value GBACS
The optimum value of P is set according to the engine speed NE.

Subsequently, in step 107, it is determined whether or not the previous control cycle was the "BACS control area". If the previous time is not the “BACS control region”, it is assumed that the “BACS control region” has been reached for the first time this time, and the control negative pressure CNP to be introduced into the negative pressure chamber 24 of the boocon 22 is controlled in step 108. The negative pressure command value BACSP of is set to "0", and the subsequent processing is once ended.

On the other hand, in step 107, if the previous time is the "BACS control area", it is determined that the "BACS control area" is continuing, and the process proceeds to step 109. Then, in step 109, it is determined whether the negative pressure command value BACSP is larger than the negative pressure request value GBACSP. Here, when the negative pressure command value BACSP is not larger than the negative pressure request value GBACSP, in step 110, the predetermined constant K is multiplied by the engine speed NE, and the multiplication result is set as the correction value α. . Then, in step 111, the negative pressure command value BACSP
Is added with the correction value α, and the addition result is set as a new negative pressure command value BACSP, and then the process is temporarily terminated.

Alternatively, in step 109, when the negative pressure command value BACSP is larger than the negative pressure request value GBACSP, in step 112 the negative pressure request value GBASP.
The CSP is set as the negative pressure command value BACSP, and the subsequent processing is temporarily terminated.

As described above, according to the fuel injection amount control device of this embodiment, the learning control of the atmospheric pressure PA and the normal EGR control are performed according to the operating region of the diesel engine 1, and the BACS is performed. The negative pressure command value BACSP is obtained by the control. Then, the ECU 47
Then, the duty control of the opening degree of the EVRV 17 is performed based on the obtained negative pressure command value BACSP. As a result, in the EVRV 17, the negative pressure from the vacuum pump 20 is adjusted based on the negative pressure command value BACSP, and is output as the control negative pressure CNP corresponding to the negative pressure command value BACSP. Then, the control negative pressure CNP is introduced into the negative pressure chamber 24 of the boocon 22 through the negative pressure passage 28, the second VSV 27 and the negative pressure passage 26, and the boocon 22 operates according to the magnitude of the control negative pressure CNP. Then, the maximum injection amount in the fuel injection pump 2 is controlled. Further, the maximum injection amount is feedback-controlled based on the supercharging pressure PiM detected by the intake pressure sensor 44.

Moreover, in this embodiment, the operating range of the diesel engine 1 is changed from "EGR control range" to "BACS
When the diesel engine 1 is accelerated, the negative pressure command value BACSP is once set to "0" and then the negative pressure request value corresponding to the accelerator lever opening ACCP is set. The maximum value is GBACSP, and the correction value α is gradually increased. And ECU4
7, the negative pressure command value BACSP obtained as described above
The duty of the opening degree of the EVRV 17 is controlled based on the above.

Therefore, the operation area is the "BACS control area".
When switched to, the negative pressure chamber 24 of the boocon 22 does not introduce a large negative pressure at once, but the control negative pressure CNP of "0" which is smaller than the negative pressure at the end of the "EGR control region". Is once introduced into the negative pressure chamber 24 as an operating pressure. Then, the control negative pressure CNP is gradually increased by the correction value α. Then, the boocon 22 operates in accordance with the change in the control negative pressure CNP, and the amount of fuel pumped from the fuel injection pump 2 to the diesel engine 1 is gradually increased.

Therefore, the amount of fuel pumped from the fuel injection pump 2 and injected from the fuel injection nozzle does not suddenly increase at the beginning of switching to the "BACS control region". That is, the fuel injection amount control is smoothly switched in switching from the “EGR control region” to the “BACS control region”. As a result, a drastic torque change does not occur in the diesel engine 1 and the drivability thereof is not deteriorated. In particular, the torque change during acceleration can be reduced. That is, during a transition of the operating state of the diesel engine 1, it is possible to suppress a sudden change in the fuel injection amount, suppress a sudden torque change in the diesel engine 2, and suppress an acceleration shock or the like.

In this embodiment, the negative pressure chamber 24 of the boocon 22 is switched to the "BACS control area".
After the negative pressure introduced into the valve is once returned to "0", the correction value α
Is gradually increasing. Moreover, the correction value α is
It is obtained by multiplying the constant K by the engine speed NE. Therefore, the correction value α becomes relatively large in a high-speed operation region where the turbocharger 10 has a large influence of the boost pressure PiM, and the negative pressure introduced into the negative pressure chamber 24 increases moderately quickly. On the other hand, in the low rotation speed operation region where the influence of the supercharging pressure PiM is small, the correction value α becomes relatively small, and the negative pressure introduced into the negative pressure chamber 24 does not increase faster than necessary.

The present invention is not limited to the above-described embodiment, but may be implemented as follows with a part of the configuration appropriately modified without departing from the spirit of the invention. (1) In the above embodiment, the negative pressure switching valve is the first VSV15.
However, the negative pressure switching valve may be composed of a single valve.

(2) In the above embodiment, the diesel engine 1 having the turbocharger 10 as the supercharger is embodied, but it may be embodied as a diesel engine not having the supercharger.

[0051]

As described in detail above, according to the present invention, when the operating region of the diesel engine is switched from the EGR control region to the fuel injection amount compensation control region, the working pressure is supplied to the pressure chamber of the injection amount compensation device. Negative pressure introduced as
The negative pressure at the end of the GR control region is controlled to be once smaller and then gradually larger. Therefore, when the operating region is switched, the amount of fuel pumped from the fuel injection pump to the diesel engine does not change abruptly, and an excellent effect that abrupt torque change in the diesel engine can be suppressed is exhibited.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram showing a basic conceptual configuration of the present invention.

FIG. 2 is a schematic configuration diagram of a diesel engine system in one embodiment embodying the present invention.

FIG. 3 illustrates an “E” executed by an ECU in one embodiment.
7 is a flowchart illustrating a "GR / BACS control routine".

FIG. 4 is a map used in a process of an “EGR / BACS control routine” in one embodiment.

[FIG. 5] Similarly, in one embodiment, “EGR BACS”
It is a map used in the processing of the "control routine".

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Diesel engine, 2 ... Fuel injection pump, 4 ... Intake manifold, 6 ... Intake passage (4 and 6 constitute an intake system), 5 ... Exhaust manifold, 7 ... Exhaust passage (5, 7)
Constitutes an exhaust system), 11 ... EGR passage, 12 ...
EGR valve, 12c ... Negative pressure chamber, 15 ... First VSV, 27
... second VSV (15 and 27 constitute a negative pressure switching valve), 17 ... EVRV as a negative pressure control valve, 22 ... boocon as a fuel compensator, 24 ... negative pressure chamber as a pressure chamber, 41 ... Water temperature sensor, 42 ... Lever sensor, 43 ... Rotation speed sensor, 44 ... Intake pressure sensor (41 to 44 constitute operating state detection means), 47 ... ECU (first negative pressure control valve control means) , The control region determination means, the negative pressure switching valve control means, and the second negative pressure control valve control means).

Claims (1)

[Claims] 1. A fuel injection pump for pumping fuel to a diesel engine, and an injection amount provided in the fuel injection pump for compensating a fuel injection amount from the fuel injection pump according to an operating pressure introduced into a pressure chamber. A compensator, to recirculate a portion of the exhaust gas emitted from the diesel engine to the intake air taken into the engine,
An exhaust gas recirculation passage that connects the exhaust system and the intake system, and an exhaust gas recirculation control valve that operates according to the negative pressure introduced into the negative pressure chamber to open and close the exhaust gas recirculation passage, One negative pressure control valve that is opened and closed to control the negative pressure introduced into the pressure chamber of the injection amount compensation device and the negative pressure chamber of the exhaust gas recirculation control valve, and is controlled by the negative pressure control valve. A negative pressure switching valve that is switched to selectively introduce a negative pressure to the pressure chamber of the injection amount compensation device or the negative pressure chamber of the exhaust gas recirculation control valve, and an operation that detects the operating state of the diesel engine. State detection means, first negative pressure control valve control means for controlling the opening degree of the negative pressure control valve according to the detection result of the operating state detection means, and fuel based on the detection result of the operating state detection means Injection amount compensation control area and exhaust gas recirculation control A fuel injection amount control device for a diesel engine, comprising: a control region determination unit that determines the region, and a negative pressure switching valve control unit that switches and controls the negative pressure switching valve according to the determination result of the control region determination unit. In the above, when it is determined by the control region determination means that the exhaust gas recirculation control region is switched to the fuel injection amount compensation control region, the negative pressure controlled by the negative pressure control valve is changed to the exhaust gas recirculation. A second negative pressure control valve control means for controlling the opening of the negative pressure control valve so that the negative pressure at the end of the control region is once decreased and then gradually increased. A fuel injection amount control device for a diesel engine.