JPH07139413A - Egr controller of diesel engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent the reduction of durability of a changeover valve resulting from unnecessary changing-over motion following acceleration or the like of a diesel engine, while suppressing generation of particulates without increase of nitrogen oxide. CONSTITUTION:The operation zone of an engine body 3 is divided into the first-third zones. A recycling flow rate adjusting valve (EGR valve) 10 is opened in the first zone and the control pressure of a pressure adjusting valve (EVRV) 26 is led to the intake air pressure sensor 31 by a changeover valve (the third VSV) 35. In the second zone, EGR valve 10 is closed and the supercharged pressure of a turbocharger 8 is led to the intake air pressure sensor 31 by VSV35. In the third zone, EGR valve 10 is closed and the control pressure is led to the intake air pressure sensor 31 by VSV 35. Accordingly, the state of VSV35 is maintained even if the operational state of engine body 3 transfers from first zone to the third zone or reversely from the third zone to the first zone.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EGR controller for a diesel engine equipped with a supercharger.

[0002]

2. Description of the Related Art Conventionally, the present applicant has previously proposed in Japanese Patent Application No. 4-250061 as one of the technologies relating to fuel injection control of a diesel engine equipped with a turbocharger and an exhaust gas recirculation (EGR) device. There is something. EGR
The device is for reducing nitrogen oxides (NOx) in the exhaust gas by extracting a part of the exhaust gas from the exhaust passage and recirculating the exhaust gas to the intake passage.

This technique will be described with reference to FIG. 8. An intake passage 52 and an exhaust passage 53 are connected to an engine body 51 of a diesel engine. Both passages 52 and 53 are connected by an EGR passage 54, and an EGR valve 55 is provided in the middle thereof. The EGR valve 55 has its negative pressure chamber 5
The EGR passage 54 is opened / closed according to the pressure acting on 6.
That is, the EGR valve 55 is set to E when the pressure is atmospheric pressure.
The GR passage 54 is closed to stop the exhaust gas recirculation. The EGR valve 55 opens the EGR passage 54 when the pressure is negative, and allows recirculation of exhaust gas.

Further, in the above technique, the fuel injection pump 57 for pumping the fuel to the engine body 51 is provided with the injection amount compensator 58. The device 58 is for correcting the fuel injection amount according to the supercharging pressure by the turbocharger 59 and the altitude above sea level (atmospheric pressure). The interior of the injection amount compensator 58 is divided into a supercharging pressure chamber 61 and a pressure chamber 62 by a diaphragm 60. The diaphragm 60 is
It is connected to a governor mechanism (not shown) via a stopper rod 63. The injection amount compensation device 58 operates the governor mechanism according to the supercharging pressure introduced into the supercharging pressure chamber 61 and the pressure introduced into the pressure chamber 62, and adjusts the maximum injection amount of the fuel injection pump 57. .

In order to supply a negative pressure to the negative pressure chamber 56 and the pressure chamber 62, a vacuum pump 64 is used as a negative pressure generating source.
Is provided. The pump 64 is connected to the negative pressure chamber 56 via a negative pressure passage 65 and a first negative pressure passage 66. Further, the vacuum pump 64 is connected to the pressure chamber 62 by the negative pressure passage 65 and the second negative pressure passage 67.

In the middle of the negative pressure passage 65, one pressure adjusting valve 68 is provided for adjusting the pressure supplied from the vacuum pump 64 to the EGR valve 55 and the injection amount compensating device 58.

A first switching valve 69 is provided in the middle of the first negative pressure passage 66. The switching valve 69, when energized (turned on), guides the pressure (control pressure) adjusted by the pressure adjustment valve 68 to the EGR valve 55. Also,
The first switching valve 69 switches the control pressure from the pressure adjusting valve 68 to the EGR valve 55 to the atmospheric pressure when the energization is stopped (OFF).

A second switching valve 70 is provided in the middle of the second negative pressure passage 67. The switching valve 70 guides the control pressure of the pressure adjusting valve 68 to the injection amount compensator 58 when energized (turned on). Further, the second switching valve 70 is
When the energization is stopped (OFF), the control pressure from the pressure adjusting valve 68 to the injection amount compensating device 58 is switched to the atmospheric pressure.

In order to guide the pressure (supercharging pressure) in the intake passage 52 boosted by the turbocharger 59 to the supercharging pressure chamber 61 of the injection amount compensator 58, the supercharging pressure chamber 61 and the intake passage 52 are supercharged. They are connected by a pressure passage 71.

Further, an intake pressure sensor 72 is used to detect the supercharging pressure in the supercharging pressure passage 71 and the control pressure in the negative pressure passage 65. The intake pressure sensor 72 has a first communication passage 73 and a first communication passage 74.
Is connected to the negative pressure passage 66 and to the supercharging pressure passage 71 by the communication passage 73 and the second communication passage 75.

A switching valve 76 is provided between the communication passage 73 and the first communication passage 74 and between the communication passage 73 and the second communication passage 75. The switching valve 76 is
When this is energized (turned on), the second communication passage 75 and the communication passage 73 are communicated, and the supercharging pressure in the supercharging pressure passage 71 is guided to the intake pressure sensor 72. The switching valve 76 is configured such that the first communication passage 74 and the communication passage 73 are provided when the energization is stopped (turned off).
To communicate the control pressure of the pressure regulating valve 68 to the intake pressure sensor 72.

A pressure regulating valve 68 and three switching valves 69,
Drive control of 70 and 76 is performed according to the map shown in FIG. In this map, the "first region Z1" and the "second region" are set according to the engine speed NE and the accelerator opening ACCP.
Area Z2 ”is set. "First area Z1"
Is a region where the exhaust gas is recirculated and the negative pressure introduction to the injection amount compensator 58 is stopped. "Second area Z
“2” is a region where the recirculation of exhaust gas is stopped and a negative pressure is introduced into the injection amount compensation device 58. Note that L1 in FIG. 9 is an acceleration line showing the relationship between the engine speed NE and the accelerator opening degree ACCP when the engine body 51 is accelerated.

When the operating state of the engine body 51 belongs to the "first zone Z1", the second switching valve 70 is turned "off" and the pressure chamber 62 of the injection amount compensator 58 is turned on.
Atmospheric pressure is introduced into. Also, the switching valve 76 is "off".
The control pressure of the pressure adjusting valve 68 is detected by the intake pressure sensor 72. The first switching valve 69 is turned on, and the target control pressure corresponding to the EGR amount is determined according to the operating state of the engine body 51 at that time.
The opening degree of the pressure adjusting valve 68 is feedback-controlled so that the actual control pressure by the intake pressure sensor 72 matches the target control pressure. By this control, the EGR valve 5
The magnitude of the negative pressure acting on the negative pressure chamber 56 of No. 5 is adjusted, and the opening amount of the EGR valve 55 is changed. Then, an amount of exhaust gas corresponding to the opening amount is recirculated to the intake passage 52 through the EGR passage 54.

When the operating state of the engine body 51 belongs to the "second zone Z2", the first switching valve 69
Is turned off, and the atmospheric pressure is introduced into the negative pressure chamber 56 of the EGR valve 55. In response to the introduction of the atmospheric pressure, the EGR valve 55 closes the EGR passage 54 and the recirculation of exhaust gas is stopped. Further, the switching valve 76 is turned on, and the supercharging pressure in the supercharging pressure passage 71 is detected by the intake pressure sensor 72. The second switching valve 70 is turned “on”. The required maximum fuel injection amount is calculated according to the operating state of the engine body 51 (including the boost pressure by the intake pressure sensor 72) at that time, and the target control output for this is determined. Then, the opening degree of the pressure adjusting valve 68 is controlled based on the target control output.

Although not particularly shown in the above-mentioned technique, in FIG. 9, the first switching valve 69, the second switching valve 70 and the second negative pressure passage 67 are omitted, and the injection amount compensating device is omitted. A system in which 58 pressure chambers 62 are open to the atmosphere is also considered.

[0016]

By the way, the above-mentioned map is set so as to comply with the current exhaust gas regulations of diesel engines. In the future, it is considered that particulates will be added to the items of this exhaust gas regulation. To add this regulation item, it is necessary to suppress the generation of particulates without increasing the nitrogen oxide (NOx) (without decreasing the EGR amount). Therefore, EGR is performed in the low engine speed range where the smoke concentration is high.
It is important to reduce the amount and increase the EGR amount in the medium speed region where the smoke concentration is low. Specifically, in the map of FIG. 9, the boundary line between the “first region Z1” and the “second region Z2” is changed from a solid line to a broken line.

However, when the switching valves 69, 70, and 76 are turned on / off according to the proposed technique according to the map after the change, the following problems occur. For example, it is assumed that the engine body 51 in the idling state is accelerated and the engine speed NE and the accelerator opening degree ACCP are changed along the acceleration line L1. In this case, the engine body 5
The region to which the first driving state belongs is the "first region Z1",
It changes in the order of “second area Z2” and “first area Z1”. The control pressure of the pressure regulating valve 68 changes in the order of "negative pressure", "atmospheric pressure", and "negative pressure" in accordance with the change in this region.
In addition, the first switching valve 69 is "on", "off",
The switching is performed in the order of "on", and the second switching valve 70 and the switching valve 76 are switched in the order of "off", "on", and "off".

As described above, in the proposed technique, the number of times each switching valve 69, 70, 76 is switched from "ON" to "OFF" or from "OFF" to "ON" increases with the change of the map. And due to this increase, the switching valve 6
There is a problem that the durability period of 9, 70, 76 becomes short.

Such a problem is caused by the first switching valve 69,
The same occurs when the second switching valve 70 and the second negative pressure passage 67 are omitted. The present invention has been made in view of the above circumstances, and an object thereof is to provide nitrogen oxides (NO
EGR control of a diesel engine with a supercharger that can suppress the generation of particulates without increasing x) and prevent the switching valve from shortening the endurance period due to unnecessary switching operation associated with acceleration of the diesel engine, etc. To provide a device.

[0020]

In order to achieve the above object, a first aspect of the present invention, as shown in FIG. 1, is a supercharging for boosting intake air taken into an engine body M2 of a diesel engine through an intake passage M1. The exhaust gas recirculation passage M5, which connects the machine M3, the exhaust passage M4 through which the exhaust gas from the engine body M2 flows, and the intake passage M1, communicate with each other when the atmospheric pressure is introduced. When the negative pressure is introduced from the negative pressure source M6 by closing M5, the exhaust gas recirculation passage M5 is opened according to the negative pressure, and the recirculation amount of the exhaust gas flowing through the passage M5 is adjusted. A recirculation amount adjusting valve M7, a fuel injection pump M8 for feeding fuel to the engine body M2, a supercharging pressure chamber M9 communicated with the supercharger M3, and a pressure chamber M10 capable of introducing atmospheric pressure. Equipped with By operating according to the supercharging pressure introduced into the supercharging pressure chamber M9 along with the operation of the supercharger M3 and the pressure introduced into the pressure chamber M10, the fuel injection amount of the fuel injection pump M8 is increased. Injection amount compensator M for correction
11, a pressure adjusting valve M12 for adjusting the pressure supplied from the negative pressure generating source M6 to the recirculation amount adjusting valve M7,
One pressure detecting means M, which is connected to the pressure regulating valve M12 and the supercharger M3, and detects one of the pressures.
13, a switching valve M14 for selectively switching the communication between the pressure adjusting valve M12 and the pressure detecting means M13, and the communication between the supercharger M3 and the pressure detecting means M13, and the operating state of the engine body M2. Operating state detecting means M for detecting
15 and the detection result of the operating state detecting means M15, the operating state of the engine body M2 at that time recirculates exhaust gas, and the control pressure after adjustment by the pressure adjusting valve M12 is applied to the pressure detecting means M13. A first region for leading the recirculation of the exhaust gas, and a second region for guiding the supercharging pressure of the supercharger M3 to the pressure detection means M13; and a recirculation of the exhaust gas, When the determination result of the area determination means M16 is the first area and the area determination means M16 determines whether the control pressure is the third area that guides the control pressure to the pressure detection means M13. The control pressure output from the adjusting valve M12 is set to a negative pressure according to the detection results of the operating state detecting means M15 and the pressure detecting means M13, and the control pressure is set to the second region and the third region. atmosphere An adjusting valve control means M17 to the determination result of the region determination unit M16 is the first region and the third
When it is in the region of, the pressure is adjusted by the switching valve M14.
12 and the pressure detection means M13 are communicated with each other, and in the second region, there is provided a switching valve control means M18 for communicating the supercharger M3 and the pressure detection means M13 with the switching valve M14.

The second invention, as shown in FIG.
Supercharger M3 for boosting the intake air taken into the engine body M32 of the diesel engine through the intake passage M31
3 and an exhaust gas recirculation passage M35 that connects the exhaust passage M34 through which the exhaust gas from the engine body M32 circulates with the intake passage M31. When the atmospheric pressure is introduced, the exhaust gas recirculation passage M35 is When the valve is closed and a negative pressure is introduced from the negative pressure generation source M36, the exhaust gas recirculation passage M35 is opened according to the negative pressure, and the recirculation for adjusting the recirculation amount of the exhaust gas flowing through the passage M35. Volume adjustment valve M
37, a fuel injection pump M38 for sending fuel to the engine body M32, a supercharging pressure chamber M39 in communication with the supercharger M33, and a pressure chamber M40 in communication with a negative pressure generating source M36. The fuel injection amount of the fuel injection pump M38 is corrected by operating according to the supercharging pressure introduced into the supercharging pressure chamber M39 and the pressure introduced into the pressure chamber M40 as the supercharger M33 operates. Injection amount compensating device M41, one pressure adjusting valve M42 for adjusting the pressure supplied from the negative pressure generation source M36 to the recirculation amount adjusting valve M37 and the injection amount compensating device M41, and the pressure adjusting valve M42. Control pressure recirculation amount adjustment valve M3 after adjustment by
A first switching valve M43 for selectively switching between introduction into the M.7 and introduction into the atmospheric pressure recirculation amount adjusting valve M37;
Injection amount compensator M4 for controlling pressure of the pressure adjusting valve M42
2 and a second switching valve M44 for selectively switching between introduction into No. 1 and introduction into the injection amount compensation device M41 of atmospheric pressure,
Based on the operating state detecting means M45 for detecting the operating state of the engine body M32 and the detection result of the operating state detecting means M45, the operating state of the engine body M32 at that time is such that exhaust gas is recirculated and the injection amount is Compensation device M4
1 for stopping the introduction of the negative pressure to the first exhaust gas, the second region for stopping the recirculation of the exhaust gas and introducing the negative pressure to the injection amount compensation device M41, and the recirculation of the exhaust gas. The determination result of the region determination means M46 for determining which is the third region for stopping and the introduction of the negative pressure to the injection amount compensation device M41, and the determination result of the region determination means M46 are the first. In the region, the control pressure of the pressure regulating valve M42 is set to a negative pressure according to the detection result of the operating state detecting means M45, and in the second region, the control pressure is set to be lower than the negative pressure in the first region. Adjusting valve control means M4 for increasing the control pressure to atmospheric pressure in the third range.
7 and the determination results of the region determination means M46 are the first region and the third region, both switching valves M43 and M44.
Thus, the control pressure of the pressure adjusting valve M42 is introduced into the recirculation amount adjusting valve M37 and the atmospheric pressure is adjusted to the injection amount compensating device M.
41, and when it is in the second region, both switching valves M
Switching valve control means M48 for introducing atmospheric pressure into the recirculation amount adjusting valve M37 and introducing the control pressure of the pressure adjusting valve M42 into the injection amount compensating device M41 by means of 43 and M44.
It has and.

[0022]

In the first aspect of the invention, as shown in FIG. 1, when the diesel engine is operating, the fuel is the fuel injection pump M.
8 is pressure-fed to the engine body M2. At this time, the intake air passing through the intake passage M1 is boosted by the supercharger M3. The supercharging pressure by the supercharger M3 is guided to the supercharging pressure chamber M9 of the injection amount compensator M11. Injection amount compensator M
Reference numeral 11 designates the supercharging pressure introduced into the supercharging pressure chamber M9 and the pressure chamber M1.
It operates according to the pressure introduced to 0 and corrects the fuel injection amount of the fuel injection pump M8.

When the engine body M2 is in operation, its operating state is detected by the operating state detecting means M15. Based on the detection result, the area determination means M16 determines whether the operating state of the engine body M2 at that time is in the first area, the second area, or the third area.

When the judgment result is in the first region, the regulating valve control means M17 drives and controls the pressure regulating valve M12,
The control pressure is set to a negative pressure according to the detection results of the operating state detecting means M15 and the pressure detecting means M13. The recirculation amount adjusting valve M7 operates according to this negative pressure, the exhaust gas recirculation passage M5 is opened, and the recirculation amount of the exhaust gas flowing through the passage M5 is adjusted.

In the first region, the switching valve control means M18 drives and controls the switching valve M14, and the pressure adjusting valve M14.
12 and the pressure detection means M13 are connected. Then,
The control pressure of the pressure adjusting valve M12 is detected by the pressure detecting means M13.

When the judgment result is in the second region, the regulating valve control means M17 drives and controls the pressure regulating valve M12,
The control pressure is set to atmospheric pressure. Then, the pressure adjusting valve M1
2, the exhaust gas recirculation passage M5 is closed, and the recirculation of exhaust gas to the engine body M2 is stopped.

In the second region, the switching valve control means M18 drives and controls the switching valve M14 to connect the supercharger M3 and the pressure detection means M13. By this communication,
The supercharging pressure by the supercharger M3 is detected by the pressure detecting means M13.

When the judgment result is in the third region, the regulating valve control means M17 drives and controls the pressure regulating valve M12,
The control pressure is set to atmospheric pressure. Then, the pressure adjusting valve M1
2, the exhaust gas recirculation passage M5 is closed, and the recirculation of exhaust gas to the engine body M2 is stopped.

Further, in the third region, the switching valve control means M18 drives and controls the switching valve M14, and the pressure adjusting valve M14.
12 and the pressure detection means M13 are connected. Due to this communication, the control pressure of the pressure adjusting valve M12 is changed to the pressure detecting means M.
Detected by 13.

Here, if the low rotation range of the engine body M2 having a high smoke concentration is set to the third region and the medium rotation range of the engine body M2 having a low smoke concentration is set to the first region, the exhaust gas It is possible to reduce the amount of gas recirculation in the low speed range and increase it in the medium speed range. For this reason, even if particulates are added to the emission control items of diesel engines in the future, the amount of particulates will be increased without increasing nitrogen oxides (NOx) (without reducing the recirculation amount of exhaust gas). It is possible to suppress the generation and adapt the diesel engine to new regulations.

Further, for example, when the diesel engine in the idling state is accelerated and the operating state of the engine body M2 shifts in the order of the first region, the third region and the first region, the pressure regulating valve M12 By the operation, the pressure to the recirculation amount adjusting valve M7 changes in the order of negative pressure, atmospheric pressure, and negative pressure. As a result, the exhaust gas recirculation is stopped after being executed, and then executed again.

On the other hand, the state of the switching valve M14 is maintained even if the region to which the operating state of the engine body M2 belongs shifts in the above order, and the pressure regulating valve M12 and the pressure detecting means M13 continue to communicate. Therefore, since the state of the switching valve M14 is maintained, the number of times of switching is reduced.

In the second aspect of the invention, as shown in FIG. 2, fuel is pumped from the fuel injection pump M38 to the engine body M32 during operation of the diesel engine. At this time, the intake air passing through the intake passage M31 is boosted by the supercharger M33. The supercharging pressure by the supercharger M33 is guided to the supercharging pressure chamber M39 of the injection amount compensator M41. Further, the negative pressure generated by the negative pressure generation source M36 is guided to the pressure chamber M40 of the injection amount compensation device M41. The injection amount compensator M41 operates according to the supercharging pressure introduced into the supercharging pressure chamber M39 and the pressure introduced into the pressure chamber M40, and corrects the fuel injection amount of the fuel injection pump M38.

When the engine body M32 is in operation, its operating state is detected by the operating state detecting means M45. Based on the detection result, the region determination means M46 determines that the operating state of the engine body M32 at that time is the first region,
It is determined whether the area is the second area or the third area.

When the judgment result is in the first region, the pressure control valve M4 is controlled by the drive control of the control valve control means M47.
2 outputs a negative pressure according to the detection result of the operating state detection means M45. By the drive control of the switching valve control means M48,
The first switching valve M43 guides the control pressure (negative pressure) of the pressure adjusting valve M42 to the recirculation amount adjusting valve M37. Further, the drive control of the switching valve control means M48 causes the second switching valve M to be controlled.
Reference numeral 44 blocks the control pressure (negative pressure) of the pressure regulating valve M42 and guides atmospheric pressure to the pressure chamber M40.

Therefore, in the first region, the pressure regulating valve M4
The recirculation amount adjusting valve M37 operates according to the control pressure of 2,
The exhaust gas recirculation passage M35 is opened, and the recirculation amount of the exhaust gas flowing through the passage M35 is adjusted. In the same region, the injection amount compensation device M41 operates according to the supercharging pressure introduced into the supercharging pressure chamber M39 and the atmospheric pressure of the pressure chamber M40, and corrects the fuel injection amount of the fuel injection pump M38. .

When the judgment result is in the second range, the pressure control valve M4 is controlled by the drive control of the control valve control means M47.
2 outputs a control pressure higher than the negative pressure in the first region. The first switching valve M43 shuts off the control pressure of the pressure adjusting valve M42 by the drive control of the switching valve control means M48, and guides the atmospheric pressure to the recirculation amount adjusting valve M37. By the drive control of the switching valve control means M48, the second switching valve M
Reference numeral 44 designates the control pressure of the pressure regulating valve M42 for controlling the injection amount compensator M.
41 to the pressure chamber M40.

Therefore, in the second region, the negative pressure is not supplied to the recirculation amount adjusting valve M37, and the exhaust gas recirculation passage M35.
Is blocked. Therefore, the exhaust gas engine body M3
Recirculation to 2 is stopped. Further, a pressure higher than the negative pressure in the first region is introduced into the pressure chamber M40, and the injection amount compensating device M41 causes the supercharging pressure introduced into the supercharging pressure chamber M39 and the pressure introduced into the pressure chamber M40. And the fuel injection amount of the fuel injection pump M38 is corrected.

When the judgment result is in the third region, the pressure regulating valve M42 is controlled by the drive control of the regulating valve control means M47.
Outputs atmospheric pressure. By the drive control of the switching valve control means M48, the first switching valve M43 guides the control pressure (atmospheric pressure) of the pressure adjusting valve M42 to the recirculation amount adjusting valve M37. The second switching valve M44 guides the atmospheric pressure to the pressure chamber M40 by the drive control of the switching valve control means M48.

Therefore, in the third region, the exhaust gas recirculation passage M35 is closed by the recirculation amount adjusting valve M37,
Recirculation of exhaust gas to the engine body M32 is stopped. Further, the injection amount compensation device M41 operates according to the supercharging pressure introduced into the supercharging pressure chamber M39 and the atmospheric pressure of the pressure chamber M40, and corrects the fuel injection amount of the fuel injection pump M38.

Here, if the low revolution range of the engine body M32 having a high smoke concentration is set to the third region and the medium revolution range of the engine body M32 having a low smoke concentration is set to the first region, the exhaust gas It is possible to reduce the amount of gas recirculation in the low speed range and increase it in the medium speed range. For this reason,
Even if particulates are added to the emission control items of diesel engines in the future, without increasing nitrogen oxides (NOx) (without reducing the recirculation amount of exhaust gas),
It is possible to suppress the generation of particulates and adapt the diesel engine to new regulations.

Further, for example, when the diesel engine in the idling state is accelerated and the operating state of the engine main body M32 shifts in the order of the first region, the third region, and the first region, the recirculation amount adjusting valve The pressure on M37 changes in the order of negative pressure, atmospheric pressure, and negative pressure by the operation of the pressure adjusting valve M42. As a result, the exhaust gas recirculation is stopped after being executed, and then executed again.

On the other hand, the states of the two switching valves M43 and M44 are retained even if the region to which the operating state of the engine body M32 belongs shifts in the above order. Therefore, the number of times the switching valves M43 and M44 are switched is reduced by the amount of the state maintained.

[0044]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the first and second inventions will be described below with reference to FIGS.

As shown in FIG. 3, the vehicle is equipped with a diesel engine 1 and a fuel injection pump 2. The engine body 3 of the diesel engine 1 has a plurality of cylinders. The engine body 3 is provided with fuel injection nozzles (not shown) corresponding to the combustion chambers of the respective cylinders. An intake passage 4 and an exhaust passage 5 are connected to the engine body 3, respectively.

A compressor 6 is provided upstream of the intake passage 4 and a turbine 7 is provided downstream of the exhaust passage 5. These compressor 6 and turbine 7 constitute a turbocharger 8 as a supercharger. The turbocharger 8 rotates the turbine 7 by the exhaust gas flowing through the exhaust passage 5, rotates the compressor 6 by the rotational force thereof, and boosts the intake air taken into each combustion chamber of the engine body 3 through the intake passage 4. It is a thing.

The intake passage 4 and the exhaust passage 5 are communicated with each other by an EGR passage 9 as an exhaust gas recirculation passage. The EGR passage 9 is a passage for performing so-called EGR, in which a part of the exhaust gas discharged from the engine body 3 is recirculated to the intake air taken into the engine body 3.

An EGR valve 10 as a recirculation amount adjusting valve is provided in the middle of the EGR passage 9. These EG
The R passage 9 and the EGR valve 10 constitute an EGR device 11. The EGR valve 10 is a diaphragm type negative pressure operated valve. The EGR valve 10 includes a valve body 12 that opens and closes the EGR passage 9, and a diaphragm 1 connected to the valve body 12.
3 and the negative pressure chamber 1 partitioned by the diaphragm 13
4 and a spring 15 arranged in the negative pressure chamber 14 to urge the diaphragm 13.

The EGR valve 10 operates as follows according to the pressure introduced into the negative pressure chamber 14. When the pressure to the negative pressure chamber 14 is atmospheric pressure, the diaphragm 13 is biased by the spring 15 and the valve body 12 closes the EGR passage 9. On the contrary, when the pressure to the negative pressure chamber 14 is negative, the diaphragm 13 is sucked and displaced, and the valve body 12
Opens the EGR passage 9. The amount of displacement of the valve body 12 at this time is proportional to the magnitude of the negative pressure. When the EGR passage 9 is opened, the exhaust gas from the engine body 3 flows through the EGR passage 9 to the intake passage 4 due to the pressure difference between the exhaust passage 5 and the intake passage 4.

Next, the distribution type fuel injection pump 2 for pumping fuel to the fuel injection nozzle of the engine body 3 will be described. As is well known, a drive shaft is rotatably provided inside the fuel injection pump 2 of this type, and a plunger is connected to the drive shaft via a cam mechanism. The drive shaft is drivingly connected to the crankshaft of the engine body 3. And, by the drive shaft being rotated in conjunction with the crankshaft,
During one rotation of the drive shaft, the plunger is reciprocated by the same number as the number of cylinders of the engine body 3. By this reciprocating movement, the fuel is pressure-fed to the fuel injection nozzle for each cylinder.

The fuel injection pump 2 has an accelerator lever 16
Is provided. The accelerator lever 16 is rotated in conjunction with the operation of an accelerator pedal (not shown) provided in the driver's seat of the vehicle. The accelerator lever 16 is connected to the spill ring on the plunger. The position of the spill ring is changed by appropriately changing the rotational position (accelerator opening ACCP) of the accelerator lever 16. With this change, the effective stroke of the plunger changes, and as a result, the maximum fuel injection amount of the fuel injection pump 2 is adjusted.

The fuel injection pump 2 has a boost altitude compensation stopper (hereinafter,
(Simply called "boocon") 17 is provided. The boocon 17 constitutes an injection amount compensating device for adjusting the maximum injection amount according to the pressure of the intake air boosted by the turbocharger 8 (supercharging pressure PiM) and the like.

The boocon 17 is provided with a supercharging pressure chamber 19 and a pressure chamber 20 which are vertically divided by a diaphragm 18. The diaphragm 18 is displaced by the relationship between the pressure acting on the supercharging pressure chamber 19 and the pressure acting on the pressure chamber 20. The upper end of a stopper rod 21 is fixed to the diaphragm 18. The stopper rod 21 is connected to the spill ring via a governor mechanism (not shown). The movement of the spill ring in the fuel increasing direction is restricted by the vertical position of the stopper rod 21 determined by the displacement of the diaphragm 18, and the fuel injection pump 2
The maximum injection amount of is determined.

In order to supply a negative pressure to the negative pressure chamber 14 of the EGR valve 10 and the pressure chamber 20 of the boocon 17, a vacuum pump 22 as a negative pressure generating source is provided. The vacuum pump 22 is drivingly connected to the crankshaft of the engine body 3 and operates in accordance with the operation of the engine body 3 to generate a negative pressure.

The vacuum pump 22 uses the negative pressure passage 23 and the first negative pressure passage 24 to form the negative pressure chamber 1 of the EGR valve 10.
4 is connected. Also, the vacuum pump 22
The negative pressure passage 23 and the second negative pressure passage 25 are connected to the pressure chamber 20 of the boocon 17. Therefore, the negative pressure generated by the operation of the vacuum pump 22 can be introduced into the negative pressure chamber 14 through the negative pressure passages 23 and 24, and can be introduced into the pressure chamber 20 through the negative pressure passages 23 and 25.

An electric vacuum regulating valve (hereinafter referred to as EVRV) 26 as a pressure adjusting valve is provided in the middle of the negative pressure passage 23. The EVRV 26 is a solenoid valve whose opening is adjusted by duty control, and by this opening adjustment, the pressure supplied to the negative pressure chamber 14 through the first negative pressure passage 24 is adjusted, and the second negative pressure is also adjusted. The pressure supplied to the pressure chamber 20 through the passage 25 is adjusted.

A first vacuum switching valve (hereinafter referred to as a first VSV) 27 serving as a first switching valve is provided in the middle of the first negative pressure passage 24. The first VSV 27 is a three-way solenoid valve having an input port, an output port and an atmosphere port, and the input port and the output port are connected to the first negative pressure passage 24. The input port and the output port are in communication when the first VSV 27 is energized (turned on). The atmosphere port and the output port are communicated with each other when the power supply is stopped (turned off). Therefore, by turning on / off the first VSV 27, E
Introduction of the pressure (control pressure) adjusted by the VRV 26 into the EGR valve 10 and introduction of atmospheric pressure into the EGR valve 10 are selectively switched.

In the first negative pressure passage 24, the EV
A vacuum damper 28 is provided between the RV 26 and the first VSV 27. The vacuum damper 28 is for smoothing the vibration of the negative pressure supplied to the negative pressure chamber 14.

In the middle of the second negative pressure passage 25, a second vacuum switching valve (hereinafter referred to as a second VSV) 29 as a second switching valve is provided. The second VSV 29 is a three-system solenoid valve having an input port, an output port and an atmosphere port, and the input port and the output port are connected to the second negative pressure passage 25. The input port and the output port are the first VSV 27
Is connected when the power is turned on. The atmosphere port and the output port are communicated with each other when the power supply is stopped (turned off). Therefore, by turning on / off the second VSV 29, E
Introduction of the control pressure of the VRV 26 into the boocon 17 and introduction of the atmospheric pressure into the boocon 17 are selectively switched.

Further, in this embodiment, in order to introduce the boost pressure by the turbocharger 8 into the boost pressure chamber 19 of the boocon 17, the boost pressure chamber 19 and the intake passage 4 are connected by the boost pressure passage 30. Has been done.

In this embodiment, the boost pressure PiM in the boost pressure passage 30 and the control pressure C in the negative pressure passage 23 are set.
In order to detect the NP, a semiconductor type intake pressure sensor 31
Is used. The intake pressure sensor 31 is connected to the first negative pressure passage 24 by a communication passage 32 and a first communication passage 33. Further, the intake pressure sensor 31 is connected to the supercharging pressure passage 30 by a communication passage 32 and a second communication passage 34.

A third vacuum switching valve (hereinafter, referred to as a switching valve) as a switching valve is provided between the communication passage 32 and the first communication passage 33 and between the communication passage 32 and the second communication passage 34. A third VSV) 35 is provided. The third VSV 35 is a three-way solenoid valve having two input ports and one output port. One input port is connected to the first communication passage 33, and the other input port is connected to the second communication passage 34. Further, the output port is connected to the communication passage 32.

One of the input port and the output port is the third
Of the VSV 35 of the third VSV 35 are connected when the energization of the VSV 35 is stopped (OFF), and the other input port and the output port are connected to the third VSV 35.
When 35 is energized (turned on), it is connected. Therefore, the communication between the supercharging pressure passage 30 and the intake pressure sensor 31 and the communication between the first negative pressure passage 24 and the intake pressure sensor 31 are selectively switched by turning on / off the third VSV 35.

In the present embodiment, in order to detect the operating state of the diesel engine 1, various sensors shown below are used in addition to the intake pressure sensor 31 described above. The engine body 3 is provided with a water temperature sensor 36 for detecting the temperature (cooling water temperature) THW of the cooling water.

A lever sensor 37 is provided near the accelerator lever 16 in the fuel injection pump 2. The lever sensor 37 is composed of a rotary position sensor and detects an accelerator opening ACCP which is a rotational position of the accelerator lever 16. Further, the fuel injection pump 2 is provided with a rotation speed sensor 38. Revolution sensor 3
8 is the rotation speed of the crankshaft in the engine body 3 (engine rotation speed N
E) is detected.

The automatic transmission mounted on the vehicle is provided with a vehicle speed sensor 39 and a shift position sensor 40. The vehicle speed sensor 39 detects the traveling speed (vehicle speed SPD) of the vehicle based on the rotation of the gear of the automatic transmission. Further, the shift position sensor 40 detects the shift position ShP of the automatic transmission. In the present embodiment, the various sensors 31,
EVRV26 and each VS based on the detection results of 36-40
An electronic control unit (hereinafter simply referred to as “ECU”) 41 is provided to drive and control the Vs 27, 29, and 35. The ECU 41 constitutes a region determination means, a regulating valve control means, and a switching valve control means. The ECU 41 includes a central processing unit (CPU), a read-only memory (ROM),
Random access memory (RAM), backup RA
M, an external input circuit and an external output circuit. These are connected to each other by a bus. A predetermined control program and initial data are stored in advance in the ROM. The CPU executes various arithmetic processes according to the control program and initial data. The RAM temporarily stores the calculation result by the CPU. Backup RAM is EC
It is backed up by a battery to retain various data even after the power supply to U41 is stopped.

In the external input circuit of the ECU 41, an intake pressure sensor 31, a water temperature sensor 36, a lever sensor 37, a rotation speed sensor 38, a vehicle speed sensor 39 and a shift position sensor 40.
Are connected. The EVRV 26, the first VSV 27, and the second VSV 2 are provided in the external output circuit of the ECU 41.
9 and a third VSV 35 are connected.

Next, the operation and effect of this embodiment configured as described above will be described. FIG. 4 shows the EVRV 26 and each VSV among the respective processes executed by the ECU 41.
27 shows a routine for controlling the operation of 27, 29 and 35. This routine is executed every predetermined time.

When a predetermined time elapses from the start of the processing of this routine last time, the ECU 41 first, at step 101, based on the signals from the various sensors 31, 36 to 40, the supercharging pressure PiM, the control pressure CNP, the cooling water temperature THW. ,
Accelerator opening ACCP, engine speed NE, vehicle speed SP
D and the shift position ShP are read respectively.

Subsequently, in step 102, the ECU 41 reads the accelerator opening ACC read in the current control cycle.
The region of the current operating state is calculated based on P and the engine speed NE. The region that this operating state can take is "First
Region Z1 "," second region Z2 "and" third region Z "
3 ”. The “first zone Z1” is a zone where the exhaust gas is recirculated and the negative pressure introduction to the boocon 17 is stopped. The “second zone Z2” is a zone where the exhaust gas recirculation is stopped and a negative pressure is introduced into the boocon 17. The “third region Z3” is a region in which recirculation of exhaust gas is stopped and negative pressure introduction to the boocon 17 is stopped.

For this calculation, the ECU 41 refers to the map of FIG. 5 stored in the ROM. In this map, the above-mentioned three regions are set in the relationship between the engine speed NE and the accelerator opening ACCP. The following points are taken into consideration in this setting. For diesel engines, it is considered that particulates will be added to the items of the current exhaust emission regulations. To add this regulation item, it is necessary to suppress the generation of particulates without increasing the nitrogen oxide (NOx) (without decreasing the EGR amount). Therefore, it is important to reduce the EGR amount in the low speed region where the smoke concentration is high and increase the EGR amount in the medium speed region where the smoke concentration is low. Therefore, in this embodiment, in order to stop the EGR in a part of the region where the EGR is performed in the conventional technique (low rotation region), in addition to the first region Z1 and the second region Z2, the third region is added. Z3 is set.

The acceleration line L1 in FIG. 5 shows changes in the engine speed NE and the accelerator opening ACCP when the engine body 3 is accelerated. Next, the ECU 41
In step 103 of FIG.
Based on the calculation result of, the current operating state is
2 ”is determined. If this determination condition is not satisfied, the ECU 41 proceeds to step 104 and determines whether the current operating state is the “first zone Z1” based on the calculation result of step 102. If this determination condition is satisfied, the ECU 41 determines in step 10
Then, the process proceeds to step 5 and the normal EGR control is executed.

More specifically, the ECU 41 controls the second VS
A signal for turning off V29 is output. In response to this signal, the atmosphere port and the output port are communicated with each other in the second VSV 29. By this communication, the atmospheric pressure is introduced into the pressure chamber 20 of the boocon 17.

Further, the ECU 41 outputs a signal for turning off the third VSV 35. In response to this signal, in the third VSV 35, the input port and the output port on the first communication passage 33 side are communicated. By this communication,
The control pressure CNP of the EVRV 26 passes through the first communication passage 33, the third VSV 35 and the communication passage 32, and the intake pressure sensor 3
Act on 1. Then, the control pressure CNP is detected by the intake pressure sensor 31.

The ECU 41 outputs a signal for turning on the first VSV 27. In response to this signal, the first VSV 27 communicates with the input port and the output port. Further, the ECU 41 determines that the engine body 3 at that time is
The target control pressure corresponding to the EGR amount is determined in accordance with the operating state of, and the opening degree of the EVRV 26 is feedback-controlled so that the actual control pressure by the intake pressure sensor 31 matches this target control pressure.

By this control, the negative pressure chamber 1 of the EGR valve 10 is
The magnitude of the negative pressure acting on the EGR valve 10 is adjusted.
The opening amount of is adjusted. Then, due to the pressure difference between the exhaust passage 5 and the intake passage 4, an amount of exhaust gas according to the opening amount is recirculated to the intake passage 4 through the EGR passage 9. When the ECU 41 executes the process of step 105,
The subsequent processing is once ended.

On the other hand, if the determination condition of step 104 is not satisfied, the ECU 41 determines that the operating state of the engine body 3 belongs to the "third zone Z3", and proceeds to step 106. In step 106, the ECU
41 controls the operation of the EVRV 26, and its control pressure C
Set NP to zero (atmospheric pressure).

Further, the ECU 41 controls the operation of each VSV 27, 29, 35 in the same manner as the above-mentioned "first zone Z1". That is, the ECU 41 outputs a signal for turning off the second VSV 29 and the third VSV 35 and turning on the first VSV 27.

In response to the signal from the ECU 41, the second VS
At V29, the atmospheric port and the output port are in communication. In the third VSV 35, the input port and the output port on the side of the first communication passage 33 are in communication. In the first VSV 27, the input port and the output port are in communication.

Therefore, the control pressure CNP after adjustment by the EVRV 26 is the same as in the above-mentioned "first region Z1".
Through the first negative pressure passage 24 and the first VSV 27, EG
It is introduced into the negative pressure chamber 14 of the R valve 10. However, the control pressure CNP is zero (atmospheric pressure). Therefore, the EGR passage 9 is closed by the valve body 12 of the EGR valve 10, and the recirculation of exhaust gas to the intake passage 4 is stopped.

At this time, the control pressure CNP of the EVRV 26
Is detected by the intake pressure sensor 31. Further, atmospheric pressure is still introduced into the pressure chamber 20 of the boocon 17. When the ECU 41 executes the process of step 106,
The subsequent processing is once ended.

On the other hand, when the determination condition of step 103 is satisfied, that is, when the operating state of the engine body 3 belongs to the "second zone Z2", the ECU 41 proceeds to step 107 and the first The signal for turning off the VSV 27 is output. In response to this signal, the first VSV 27 communicates with the atmospheric port and the output port. Due to this communication, the atmospheric pressure is the negative pressure chamber 1 of the EGR valve 10.
Introduced in 4. Therefore, the EGR passage 9 is connected to the EGR valve 1
The exhaust gas intake passage 4 is closed by the zero valve body 12
The recirculation to is stopped.

The ECU 41 also outputs a signal for turning on the second VSV 29. In response to this signal, the input port and the output port are connected in the second VSV 29. The ECU 41 turns on the third VSV 35.
The signal for making it output is output. In response to this signal, the third
In the VSV 35, the input port and the output port on the second communication passage 34 side are communicated with each other. Therefore, the supercharging pressure by the turbocharger 8 is increased by the supercharging pressure passage 30 and the second communication passage 3.
4, acting on the intake pressure sensor 31 through the third VSV 35 and the communication passage 32. Then, the supercharging pressure PiM is detected by the intake pressure sensor 31.

Next, in step 108, the ECU 41 calculates the negative pressure request value GBACSP. This value GBA
The CSP is for determining the control pressure CNP to be introduced into the pressure chamber 20 of the boocon 17. ECU 41
Is the accelerator opening ACC that was read this time.
Based on P, engine speed NE and supercharging pressure PiM, reference is made to the map shown in FIG. This map defines the negative pressure request value GBACSP based on the relationship between the accelerator opening ACCP and the supercharging pressure PiM, and is stored in advance in the ROM.

Subsequently, in step 109, the ECU 41 determines whether or not the operating state of the engine body 3 at the time of executing this routine last time belongs to the "second zone Z2". If this judgment condition is not satisfied, EC
U41 is the engine body 3 when executing this routine.
It is determined that the operating state of No. 2 has become the "second zone Z2" for the first time, the process proceeds to step 110, and the negative pressure command value BACSP is set to "0". After executing the processing of step 110, the ECU 41 once ends the subsequent processing.

On the other hand, when the determination condition of step 109 is satisfied, the ECU 41 determines that the "second zone Z2" is continuing and shifts to step 111. ECU4
In step 111, it is determined whether the negative pressure command value BACSP is larger than the negative pressure request value GBACSP. If this determination condition is not satisfied (BACSP ≤
In step 112, the ECU 41 multiplies a predetermined constant K by the engine speed NE and sets the multiplication result as a correction value α.

Then, in step 113, the ECU 41 adds the correction value α to the negative pressure command value BACSP,
The addition result is set as a new negative pressure command value BACSP. After executing the process of step 113, the ECU 41 temporarily ends the process.

When the determination condition of step 111 is satisfied (BACSP> GBACSP), the ECU 41 sets the negative pressure request value GBACSP as the negative pressure command value BACSP in step 114. After executing the processing of step 114, the ECU 41 once ends the subsequent processing.

The ECU 41 executes the steps 110, 11
When the negative pressure command value BACSP is set at 3, 114, the negative pressure command value BACSP is set in accordance with a separately prepared routine.
The duty of the opening degree of the EVRV 26 is controlled based on the above.
By this control, in the EVRV 26, the negative pressure from the vacuum pump 22 is adjusted based on the negative pressure command value BACSP. The adjusted negative pressure (control pressure CNP) is the second
Is introduced into the pressure chamber 20 of the boocon 17 through the negative pressure passage 25 and the second VSV 29. The maximum injection amount in the fuel injection pump 2 is controlled by operating the boocon 17 according to the introduced control pressure CNP. Further, the maximum injection amount is feedback-controlled based on the magnitude of the supercharging pressure PiM detected by the intake pressure sensor 31.

The above-mentioned steps 109 to 114 are performed when the operating region to which the engine body 3 belongs shifts from the "first region Z1" or "third region Z3" to the "second region Z2". Is a process for preventing a sudden change in

More specifically, when the operating region shifts to the "second region Z2", the negative pressure command value BACSP is once set to "0" (steps 109 and 110). Then, the negative pressure command value BACSP is gradually increased by the correction value α with the negative pressure request value GBACSP corresponding to the magnitude of the accelerator opening ACCP being the maximum value (steps 111 to 11).
3). Therefore, a large negative pressure is not introduced at once to the pressure chamber 20 of the boocon 17, but the control pressure CNP (“0” in this case) smaller than the negative pressure at the end of the “first zone Z1” is the pressure. Once introduced into the chamber 20. After that, the control pressure CNP is gradually increased by the correction value α. Then, the boocon 17 operates in accordance with the change in the control pressure CNP, and the fuel injection pump 2 moves to the diesel engine 1
The amount of fuel pumped to is gradually increased.

Therefore, the operation area is "second area Z2".
Immediately after switching to, the amount of fuel pumped from the fuel injection pump 2 and injected from the fuel injection nozzle does not suddenly increase. In other words, the fuel injection amount control is smoothly switched at the time of transition from the "first region Z1" or the "third region Z3" to the "second region Z2".
As a result, abrupt torque change at the time of acceleration of the diesel engine 1 is suppressed and deterioration of drivability is prevented.

Further, in the processing of step 112, the correction value α is obtained by multiplying the constant K and the engine speed NE for the following reason. This is because the correction value α is relatively increased and the negative pressure introduced into the pressure chamber 20 is increased promptly and appropriately in a high rotation operation region where the turbocharger 8 has a large influence of the boost pressure PiM. Further, in the low rotation speed operation region where the influence of the supercharging pressure PiM is small, the correction value α is made relatively small to prevent the negative pressure introduced into the pressure chamber 20 from increasing faster than necessary. .

As described above, in the present embodiment, the engine speed NE and the accelerator opening ACCP are set in consideration of the fact that particulates will be added to the items of the current exhaust gas regulation of the diesel engine 1 in the future. In this relationship, three areas are set. That is, a part of the region where the EGR is performed in the conventional technique (low speed region)
In order to stop the EGR at, the third area Z3 is set in addition to the first area Z1 and the second area Z2. Then, in the first zone Z1, the EGR valve 10 is opened to recirculate the exhaust gas, and in the second zone Z2 and the third zone Z3, the EGR valve 10 is closed to recirculate the exhaust gas. Is to be stopped.

Therefore, according to the present embodiment, the EGR amount is reduced in the low revolution region where the smoke concentration is high, and the EGR amount is increased in the medium revolution region where the smoke concentration is low, so that NOx is not increased (the EGR amount is increased). The amount of particulates can be suppressed.

Furthermore, in this embodiment, when the operating state of the engine body 3 belongs to the "first zone Z1", the second V
The SV 29 and the third VSV 35 are turned “off”, and the first VSV 27 is turned “on”. The target control pressure corresponding to the EGR amount according to the operating state of the engine body 3 at that time is determined, and the opening degree of the EVRV 26 is feedback-controlled so that the actual control pressure matches this target control pressure.

The operating condition of the engine body 3 is "second
Zone Z2 ”of the second VSV 29 and the third VSV 29
VSV35 is turned on, and the first VSV27 is turned off. Depending on the operating state of the engine body 3 at that time (including the boost pressure PiM by the intake pressure sensor 31),
The required maximum fuel injection amount is calculated, the target control output for this is determined, and the opening degree of the EVRV 26 is controlled based on this value.

The operating condition of the engine body 3 is "3rd
Control range C of the EVRV 26 when belonging to the region Z3 of
NP is set to zero (atmospheric pressure). As described above, “first area Z
1 ”similarly to the second VSV 29 and the third VSV 35.
Is turned off and the first VSV 27 is turned on.
Therefore, even when the operating state shifts from the “third zone Z3” to the “first zone Z1”, the reverse is the “first zone Z3”.
In the case of shifting from "1" to "third zone Z3", the second
The VSV 29 and the third VSV 35 of “1” are kept “off”, and the first VSV 27 of “1” is kept “on”.

Therefore, for example, when the diesel engine 1 in the idling state is accelerated along the acceleration line L1 in FIG. 5, the operating states of the engine body 3 are "first zone Z1" and "third zone". Z3 ”and“ first area Z1 ”are moved in this order. At this time, according to the routine of FIG. 4 described above, the control pressure CNP of the EVRV 26 changes in the order of negative pressure, zero (atmospheric pressure), and negative pressure. As a result, the exhaust gas recirculation is stopped after being executed, and then executed again. On the other hand, the status of each VSV 27, 29, 35 is
It is retained even if the region to which the operating state of the engine body 3 belongs shifts as described above. Therefore, in the third area Z3, each VSV 27, 29, 35 is similar to the second area Z2.
In this embodiment, the number of times the VSVs 27, 29, and 35 are switched can be reduced as compared with the case where the switching is performed (corresponding to the related art). As a result, the VSVs 27, 2 can be switched by the unnecessary switching operation accompanying the acceleration of the diesel engine 1 and the like.
It is possible to prevent the durability period of 9,35 from being shortened.

In addition, if it is assumed that the second area in the third area Z3 is
When the VSVs 27, 29, 35 are switched in the same manner as in the area Z2 of No. 2, the first negative pressure passage 24 and the second negative pressure passage 25
The pressure inside will repeat negative pressure and atmospheric pressure, and E
The accuracy of the control pressure CNP of the VRV 26 deteriorates, and it becomes difficult to comply with exhaust emission regulations. However, in the present embodiment, as described above, the unnecessary switching operation of the VSVs 27, 29, 35 is eliminated, so that the negative pressure and the atmospheric pressure in the negative pressure passages 24, 25 are less repeated. Therefore, the control pressure CN
The accuracy of P can be prevented from deteriorating, the EGR valve 10 can be operated with high accuracy, and exhaust regulations can be reliably met.

Furthermore, the sounds generated when the VSVs 27, 29, 35 are turned on and off are transmitted to the inside of the vehicle even if they are floated. In the present embodiment, the VSVs 27, 29, 35 are less likely to be switched on and off during the acceleration of the diesel engine 1, so that the number of times the sound is generated can be suppressed.

The present invention is not limited to the above-described embodiments, but may be implemented as follows with a part of the configuration appropriately changed without departing from the spirit of the invention. (1) FIG. 7 shows another embodiment in which the second invention is embodied. In this alternate embodiment, the first VSV 27, second
The VSV 29 and the second negative pressure passage 25 are omitted, and the pressure chamber 20 of the boocon 17 is open to the atmosphere. Correspondingly, in the flowchart of FIG. 4, both VSVs 27,
The switching of 29 and the processing of steps 107 to 114 are omitted.

With this change, when the operating state of the engine body 3 belongs to the "first zone Z1", the third V
SV35 is "off", EVRV26 control pressure CN
P is detected by the intake pressure sensor 31. Further, the target control pressure corresponding to the EGR amount is determined according to the operating state of the engine body 3 at that time, and the EVRV 26 is opened so that the actual control pressure by the intake pressure sensor 31 matches this target control pressure. The degree is feedback controlled.

By this control, the negative pressure chamber 1 of the EGR valve 10 is
The magnitude of the negative pressure acting on the EGR valve 10 is adjusted.
The opening amount of is adjusted. Then, due to the pressure difference between the exhaust passage 5 and the intake passage 4, an amount of exhaust gas according to the opening amount is recirculated to the intake passage 4 through the EGR passage 9.

When the operating state of the engine body 3 belongs to the "second zone Z2", the third VSV 35 is turned on, and the supercharging pressure by the turbocharger 8 is the intake pressure sensor 3
Detected by 1. Further, the control pressure CNP of the EVRV 26 is set to zero (atmospheric pressure). Therefore, the EGR passage 9 is closed by the EGR valve 10, and the circulation of the exhaust gas to the intake passage 4 is stopped.

When the operating state of the engine body 3 belongs to the "third zone Z3", the operation of the EVRV 26 is controlled and the control pressure CNP is set to zero (atmospheric pressure). Further, the third VSV 35 is turned “off”. EVRV26
The control pressure CNP is introduced into the negative pressure chamber 14 of the EGR valve 10. However, since the control pressure CNP is zero (atmospheric pressure), the EGR passage 9 is blocked by the valve body 12 of the EGR valve 10, and the exhaust gas is exhausted. Recirculation to the intake passage 4 is stopped.

Therefore, also in the case of this other embodiment, by reducing the recirculation amount of the exhaust gas in the low rotation range (third zone Z3) and increasing it in the medium rotation range (first zone Z1),
Generation of particulates can be suppressed without increasing nitrogen oxides.

Further, when accelerating the diesel engine 1,
The operating state of the engine body 3 shifts from the "first zone Z1" to the "third zone Z3", or vice versa, shifts from the "third zone Z3" to the "first zone Z1". If so, the state of the third VSV 35 can be maintained. Therefore, the third VSV3 can be changed by an unnecessary switching operation during acceleration or the like.
It is possible to prevent the durability period of 5 from being shortened.

Further, as in the above-described embodiment, the unnecessary switching operation of the third VSV 35 is eliminated, so that the accuracy of the control pressure CNP is prevented from deteriorating and the EGR valve 10 is operated with high accuracy to regulate the exhaust gas. It is possible to respond reliably. In addition, during the acceleration of the diesel engine 1, the third VSV3
Since it becomes difficult to switch the state of No. 5, it is possible to reduce the number of times the sound is generated due to the switching.

(2) Third VS in the third area Z3
The switching operation of V35 may be the same as the switching operation of the third VSV 35 in the second region Z2. (3) In the above embodiments, the present invention is embodied in a diesel engine equipped with an exhaust turbine supercharger (turbocharger). However, a mechanical supercharger driven by a crankshaft to send air under pressure, etc. It may be embodied in a diesel engine equipped with a supercharger.

[0111]

As described above in detail, in the first invention, the region to which the operating state of the engine body belongs is divided into first to third regions, and the exhaust gas is recirculated and the pressure is divided in the first region. The control pressure adjusted by the adjusting valve is guided to the pressure detecting means. In the second region, the recirculation of exhaust gas is stopped and the supercharging pressure by the supercharger is guided to the pressure detecting means. In the third region, the recirculation of exhaust gas is stopped and the control pressure of the pressure regulating valve is guided to the pressure detecting means.

Therefore, if the low rotation range of the engine body with high smoke concentration is set to the third region and the medium rotation range of the engine body with low smoke concentration is set to the first region,
By reducing the recirculation amount of exhaust gas in the low rotation speed region and increasing it in the middle rotation speed region, it is possible to suppress the generation of particulates without increasing the nitrogen oxides.

In the first region and the third region, the control pressure of the pressure regulating valve is made different, but the switching operation of the switching valve is not performed. Therefore, when the diesel engine accelerates,
The transition from the first area to the third area and vice versa
The state of the switching valve is maintained even when the area changes to the first area. Therefore, it is possible to prevent the endurance period of the switching valve from being shortened due to an unnecessary switching operation during acceleration or the like.

Further, in the second aspect of the present invention, the region to which the operating state of the engine body belongs is divided into first to third regions, the exhaust gas is recirculated in the first region, and the injection amount compensating device has a negative effect. Stop pressure introduction. In the second region, the exhaust gas recirculation is stopped and a negative pressure is introduced into the injection amount compensator. In the third region, the exhaust gas recirculation is stopped,
In addition, the introduction of the negative pressure to the injection amount compensation device is stopped.

Therefore, if the low rotation range of the engine body having a high smoke concentration is set to the third region and the medium rotation range of the engine body having a low smoke concentration is set to the first region,
By reducing the recirculation amount of exhaust gas in the low rotation speed region and increasing it in the middle rotation speed region, it is possible to suppress the generation of particulates without increasing nitrogen oxides.

In the first area and the third area, the control pressure of the pressure adjusting valve is made different, but the first and second areas are different.
The switching operation of the switching valve is not performed. Therefore, even when the operating state of the engine body shifts from the first region to the third region during acceleration of the diesel engine, or vice versa, The states of the first and second switching valves are retained. Therefore, it is possible to prevent the endurance period of both switching valves from being shortened due to an unnecessary switching operation during acceleration or the like.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram of a first invention.

FIG. 2 is a conceptual configuration diagram of a second invention.

FIG. 3 is a schematic configuration diagram showing an EGR control device of a diesel engine with a supercharger in an embodiment embodying the first and second inventions.

FIG. 4 is a flowchart illustrating a routine executed by an ECU for driving and controlling an EVRV and each VSV in one embodiment.

FIG. 5 is a characteristic diagram showing a map in which first to third regions are defined in one embodiment.

FIG. 6 is a characteristic diagram showing a map in which negative pressure required values for accelerator opening and supercharging pressure are defined in one embodiment.

FIG. 7 shows another embodiment embodying the first invention,
It is a schematic structure figure showing an EGR control device of a diesel engine with a supercharger.

FIG. 8 is a schematic configuration diagram showing a diesel engine with a supercharger, a fuel injection pump, and the like in the related art.

FIG. 9 is a characteristic diagram showing a map in which first and second regions are defined in the conventional technique.

[Explanation of symbols]

2 ... Fuel injection pump, 3 ... Engine body, 4 ... Intake passage, 5 ... Exhaust passage, 8 ... Turbocharger as supercharger, 9 ... EGR passage as exhaust gas recirculation passage, 10
... EGR valve as recirculation amount adjusting valve, 17 ... boocon as injection amount compensating device, 19 ... supercharging pressure chamber, 20 ... pressure chamber, 22 ... vacuum pump as negative pressure generating source, 26
EVRV as pressure adjusting valve, 27 ... First VSV as first switching valve, 29 ... Second VSV as second switching valve, 31 ... Intake pressure sensor as pressure detecting means, 35 ... Switching Third VSV as valve, 37 ... Lever sensor forming part of operating condition detecting means, 38 ... Rotation speed sensor forming part of operating condition detecting means, 41 ...
ECU constituting region judging means, adjusting valve control means and switching valve control means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02D 41/02 D 8011-3G F02M 25/07 530 A 550 R

Claims (2)

[Claims] 1. A supercharger for increasing the pressure of intake air taken into an engine body of a diesel engine through an intake passage, and an exhaust gas recirculation for connecting the exhaust passage through which exhaust gas from the engine body circulates with the intake passage. The exhaust gas recirculation passage is provided in the circulation passage and closes the exhaust gas recirculation passage when the atmospheric pressure is introduced, and opens the exhaust gas recirculation passage according to the negative pressure when the negative pressure is introduced from the negative pressure generation source. However, a recirculation amount adjusting valve that adjusts the recirculation amount of the exhaust gas flowing through the passage, a fuel injection pump that pressure-feeds the fuel to the engine body, and a supercharging pressure chamber that communicates with the supercharger. A pressure chamber capable of introducing atmospheric pressure, and by operating according to the supercharging pressure introduced into the supercharging pressure chamber along with the operation of the supercharger and the pressure introduced into the pressure chamber, Fuel injection amount of fuel injection pump An injection amount compensating device that corrects the pressure, a pressure adjusting valve for adjusting the pressure supplied from the negative pressure generating source to the recirculation amount adjusting valve, and one of the pressure adjusting valve and the supercharger, which are in communication with each other. One pressure detecting means for detecting the pressure of the engine, a switching valve for selectively switching the communication between the pressure adjusting valve and the pressure detecting means, and the communication between the supercharger and the pressure detecting means, Based on the operating state detecting means for detecting the operating state of the main body and the detection result of the operating state detecting means, the operating state of the engine main body at that time is to recirculate the exhaust gas and control after adjustment by the pressure adjusting valve. A first region for guiding pressure to the pressure detection means and stopping the recirculation of the exhaust gas,
And a second region for guiding the supercharging pressure of the supercharger to the pressure detecting means, and a third region for stopping the recirculation of the exhaust gas and guiding the control pressure to the pressure detecting means. Area determining means for determining whether or not, and when the determination result of the area determining means is the first area,
The control pressure output from the pressure adjusting valve is set to a negative pressure according to the detection results of the operating state detecting means and the pressure detecting means, and when the control pressure is in the second region and the third region, the control pressure is atmospheric pressure. When the determination result of the area determination means is the first area and the third area, the switching valve communicates the pressure adjustment valve and the pressure detection means, and the second area. At this time, an EGR control device for a diesel engine with a supercharger, comprising: a switching valve control means for communicating the supercharger and the pressure detection means with a switching valve. 2. A supercharger for increasing the pressure of intake air taken into an engine body of a diesel engine through an intake passage, and an exhaust gas recirculation system for communicating the exhaust passage through which exhaust gas from the engine body flows with the intake passage. Provided in the circulation passage, the exhaust gas recirculation passage is closed when the atmospheric pressure is introduced, and when the negative pressure is introduced from the negative pressure source, the exhaust gas recirculation passage is opened according to the negative pressure, A recirculation amount adjusting valve that adjusts the recirculation amount of the exhaust gas flowing through the passage, a fuel injection pump that pressure-feeds fuel to the engine body, a supercharging pressure chamber that communicates with the supercharger, and a negative pressure. The fuel is provided with a pressure chamber communicating with a generation source, and the fuel is operated by operating in accordance with the supercharging pressure introduced into the supercharging pressure chamber along with the operation of the supercharger and the pressure introduced into the pressure chamber. Corrects fuel injection amount of injection pump Injection amount compensating device, one pressure adjusting valve for adjusting the pressure supplied from the negative pressure generation source to the recirculation amount adjusting valve and the injection amount compensating device, and the control pressure after adjustment by the pressure adjusting valve. A first switching valve for selectively switching between introduction into the recirculation amount adjusting valve and introduction of atmospheric pressure into the recirculation amount adjusting valve, and an injection amount compensating device for the control pressure of the pressure adjusting valve. Second switching valve for selectively switching between introduction of the engine and introduction into the injection amount compensator of atmospheric pressure, operating state detecting means for detecting the operating state of the engine body, and operating state detecting means Based on the detection result, the operating state of the engine at that time recirculates the exhaust gas and stops the introduction of the negative pressure into the injection amount compensating device, and a first region,
A second region in which the recirculation of the exhaust gas is stopped and a negative pressure is introduced into the injection amount compensation device, and the recirculation of the exhaust gas is stopped and the negative pressure introduction in the injection amount compensation device is stopped. An area determining unit that determines which of the third areas is included; and when the determination result of the area determining unit is the first area,
The control pressure of the pressure regulating valve is set to a negative pressure according to the detection result of the operating state detection means, and when in the second region, the control pressure is set to a pressure higher than the negative pressure in the first region, Control valve for controlling the control pressure to atmospheric pressure when the pressure control valve is in the range of 1), and the control valve for controlling the pressure control valve by both switching valves when the determination result of the range determination means is in the first range and the third range. When the pressure is introduced into the recirculation amount adjusting valve and the atmospheric pressure is introduced into the injection amount compensating device, and when it is in the second region, both switching valves introduce the atmospheric pressure into the recirculating amount adjusting valve and the pressure adjusting valve. EGR control device for a diesel engine with a supercharger, comprising: a switching valve control means for introducing the control pressure of 1. to the injection amount compensation device.