JP2002276405A - Exhaust emission control device of diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly and continuously combust PM collected in a DPF in a large operating range of an engine. SOLUTION: This exhaust emission control device of a diesel engine comprises a turbo charger having an exhaust turbine disposed in an exhaust passage and an intake compressor disposed in an intake passage, a first EGR passage for communicating the exhaust passage on the upstream side from the exhaust turbine with the intake passage on the downstream side from the intake compressor, a first EGR valve disposed in the first EGR passage, and an oxidation catalyst and a particulate filter that are disposed in the exhaust passage on the downstream side from the exhaust turbine. When an exhaust temperature range of the engine lies higher than an active temperature range of the oxidation catalyst, the exhaust emission control device performs the control for throttling the first EGR valve. When the exhaust temperature range of the engine lies lower than the active temperature range of the oxidation catalyst, the exhaust emission control device performs the control for throttling either or both of an intake shutter and an exhaust shutter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for removing particulates in exhaust gas of a diesel engine.

[0002]

2. Description of the Related Art Regulations on the exhaust gas of recent internal combustion engines, especially diesel engines, have been strengthened year by year, and in particular, particulates (hereinafter referred to as P
M) is urgently needed. A diesel particulate filter (hereinafter, DPF) is known as a device for removing the PM from exhaust gas, and a movement to oblige a vehicle equipped with a diesel engine to be equipped with the DPF is also in full swing.

[0003] By the way, in a DPF mounted on a vehicle equipped with a diesel engine, PM collected by repeated operation of the engine accumulates. Therefore, it is necessary to regenerate the DPF by burning the collected PM. is there. As a method of this regeneration, a method of burning PM by heating with an electric heater, a burner or the like is known. When this method of burning PM is adopted, during the reburning of DPF, PM
Therefore, a system in which a plurality of DPFs are arranged in parallel in the exhaust passage to alternately perform collection and combustion is caused, and a problem that the apparatus becomes large-scale occurs. Further, in the method of burning PM, the temperature at the time of burning PM becomes high, so that there is a problem in securing the durability of the filter. For this reason, the method of burning PM is as follows:
It has not been widely adopted.

[0004] In view of the above problems, a continuous regeneration type exhaust purification device has been proposed in recent years as an exhaust purification device for a diesel engine.
No. 49 and the like. With reference to FIG. 7, a conventionally known exhaust gas purifying apparatus for a continuous regeneration type diesel engine will be described.

An engine body 2 including a cylinder block and a cylinder head is provided with an intake manifold 3 forming a part of an intake passage and an exhaust manifold 4 forming a part of an exhaust passage. An intake pipe 5 constituting a part of an intake passage is connected to the intake manifold 3, and an air cleaner 6 for purifying intake air is arranged at the most upstream portion of the intake pipe 5. The intake air purified by the air cleaner 6 passes through the intake pipe 5 and is supplied to the cylinder (not shown) via the intake manifold 3. An exhaust pipe 7 forming a part of an exhaust passage is connected to the exhaust manifold 4, and exhaust gas generated in the cylinder is discharged through the exhaust manifold 4 and the exhaust pipe 7.

[0006] The illustrated diesel engine is provided with a turbocharger 8 for supercharging intake air. The turbocharger 8 has an exhaust turbine 81 provided in the exhaust pipe 7 and an intake compressor 82 provided in the intake pipe 5. The illustrated diesel engine includes an exhaust gas recirculation (hereinafter referred to as EGR) passage 9 that connects the exhaust pipe 7 upstream of the exhaust turbine 81 and the intake pipe 5 downstream of the intake compressor 82. I have. An EGR valve 11 is provided in the EGR passage 9. The EGR valve 11 is connected to, for example, a negative pressure tank (not shown), and the opening degree, that is, the EGR rate is controlled by controlling the amount of negative pressure supplied according to the operating state by a control means 10 described later. Is done. Note that E
As is well known, the GR is an exhaust gas purifying unit that suppresses NOx by introducing intake air obtained by circulating exhaust gas after combustion into a cylinder. Further, in the conventional example, the connection between the EGR passage and the engine side is an intake pipe and an exhaust pipe, but it is obvious that the intake and exhaust manifolds constituting a part of the intake passage may be used.

An exhaust pipe downstream of the exhaust turbine 81
7, oxidation catalyst 12, DPF 13 and
And a NOx catalyst 14 are provided. The oxidation catalyst 12
For example, honeycomb-shaped cordierite or heat-resistant steel
The surface of a carrier made of
A coated layer of platinum,
Catalytic activity of precious metals such as rhodium and rhodium
What carried the component is used. This oxidation catalyst 12
Oxidizes NO in exhaust gas to NO₂Generate
In both cases, HC and CO in the exhaust gas are oxidized to H₂O and C
O₂Is generated. The DPF 13 is, for example, a porous core.
Dierite or silicon carbide creates many cells
Formed in parallel, the inlet and outlet of the cell are closed alternately
The so-called wall flow type honeycomb filter
Layers of ruta and ceramic fibers in stainless steel perforated tube
A wound fiber type filter is used, and P in exhaust gas is used.
Collect M. The configuration and components of the NOx catalyst 14 are
The same catalyst as the oxidation catalyst 12 can be used.
NOx such as NO in the N₂And H₂Reduce to O. this
Such a continuous regeneration type DPF is discharged by the oxidation catalyst 12.
NO in gas and gas is NO ₂And oxidized under the oxidation catalyst 12.
NO flowing into the DPF 13 disposed on the upstream side₂Captured by
The collected PM is burned. At this time, low
PM burns at a low temperature, so electric heaters and burners
There is no need to provide any special heating means.
While burning M continuously, it also collects PM at the same time
It is not necessary to provide multiple DPFs to perform
Has the advantage of being simple and compact
You.

The illustrated diesel engine has an engine speed sensor 15 for detecting the engine speed.
An accelerator sensor 16 for detecting the amount of depression of an accelerator pedal (accelerator opening), an intake temperature sensor 17 disposed in the intake manifold 3 for detecting the temperature of intake air taken into a cylinder, the engine rotational speed detection sensor 15, A control means 10 is provided for controlling the amount of fuel injected into the cylinder by the EGR valve 11 or a fuel injection device (not shown) based on detection signals from the accelerator sensor 16 and the intake air temperature sensor 17. Control means 1
0 is provided with a memory for storing a so-called fuel injection amount as shown in FIG. 10 in which a combustion injection amount is set using the engine rotation speed and the accelerator opening as parameters, and the engine rotation speed detection sensor 15 and the accelerator sensor 16 The basic fuel injection amount is determined based on the detection signal. Then, the control means 10 corrects the basic fuel injection amount based on the detection value of the intake air temperature sensor 15 to determine the final fuel injection amount. In addition, the final fuel injection amount is not only the intake air temperature,
The correction can be made at any time with reference to other various parameters (atmospheric pressure, smoke limit injection amount, and the like).

[0009]

The oxidation catalyst 12 described above
The efficiency of the reaction for oxidizing NO to NO _2, that is, the conversion, greatly changes with the catalyst temperature in the current catalyst. For example, a good oxidation reaction can be seen in the active region between 250 ° C. and 400 ° C., but the conversion of NO to NO ₂ is not sufficiently performed in other regions. That is, no sufficient NO ₂ component for oxidizing PM is generated. FIG. 8 shows the amount of CO ₂ generated by the oxidative combustion of PM in comparison with the exhaust gas temperature of the engine. From this, it can be seen that PM is actively combusted between 250 ° C. and 400 ° C. to regenerate the filter. Conversely, PM combustion (= regeneration of DPF) is hardly performed in other temperature regions.

A diesel engine mounted on a vehicle has:
The engine speed and the engine load change every moment depending on the operation state, and the temperature of the exhaust gas discharged therefrom also changes according to the operation state. FIG. 9 shows the temperature range of the exhaust gas using the engine speed and the engine load as parameters. As can be seen from FIG. 9, when the engine is under a high load and the rotation speed is high (region X), and when the engine is at a low load and the rotation speed is low (region Z), the temperature of the catalyst is set in the active temperature region Y (250 (400 ° C. to 400 ° C.), and the oxidation catalyst does not sufficiently oxidize NO to NO ₂ . Therefore DP
Since the PM trapped by the F is not sufficiently burned, the PM trapping efficiency of the filter is also reduced, resulting in an undesired result such as quicker clogging of the filter itself.

The present invention has been made in view of the above points, and a main technical problem thereof is to reliably and continuously burn PM trapped in a DPF in a wide operating range of an engine.

[0012]

According to the present invention, there is provided a turbocharger having an exhaust turbine disposed in an exhaust passage and an intake compressor disposed in an intake pipe. A first EGR passage that connects an exhaust passage upstream of the exhaust turbine and an intake pipe downstream of the intake compressor, a first EGR valve disposed in the first EGR passage, In an exhaust gas purifying apparatus for a diesel engine including an oxidation catalyst and a particulate filter disposed in an exhaust passage downstream of the exhaust turbine, exhaust temperature region detecting means for detecting an engine exhaust temperature region; When the exhaust gas temperature range of the engine detected by the range detecting means is higher than the active temperature range of the oxidation catalyst, the first EG
Control means for performing control for narrowing the R valve. An exhaust gas purification apparatus for a diesel engine is provided.

The exhaust temperature region detecting means includes an engine load detecting means for detecting an engine load, an engine rotational speed detecting means for detecting an engine rotational speed, and an exhaust temperature of the engine using the engine load and the engine rotational speed as parameters. An exhaust temperature range map in which regions are set.

A second EGR passage connecting an exhaust passage downstream of the exhaust turbine and an intake pipe upstream of the intake compressor; and a second EGR disposed in the second EGR passage. A valve for controlling the opening of the second EGR valve when the exhaust temperature range of the engine detected by the exhaust temperature range detecting means is higher than the active temperature range of the oxidation catalyst. An exhaust gas purification device for a diesel engine.
It is preferable that a cooling means for cooling the EGR gas is provided in the second EGR passage.

Further, according to the present invention, a turbocharger having an exhaust turbine disposed in an exhaust passage and an intake compressor disposed in an intake passage, an exhaust passage upstream of the exhaust turbine, and the intake compressor A first EGR passage communicating with a downstream intake pipe, and a first EGR passage;
An exhaust gas purifying apparatus for a diesel engine, comprising: a first EGR valve disposed in a GR passage; and an oxidation catalyst and a particulate filter disposed in an exhaust passage downstream of the exhaust turbine. An intake shutter disposed in the intake pipe upstream of a connection between the EGR passage and the intake pipe; and an exhaust shutter disposed in the exhaust passage downstream of the connection between the first EGR passage and the exhaust passage. Exhaust shutter, exhaust temperature range detecting means for detecting an exhaust temperature range of the engine, and an exhaust temperature range of the engine detected by the exhaust temperature range detecting means becomes a lower temperature range than an active temperature range of the oxidation catalyst. Control means for performing control to narrow down one or both of the intake shutter and the exhaust shutter in some cases, It is subjected.

The control means may control the opening degree of the intake shutter and the exhaust shutter in a stepwise manner as the exhaust temperature area of the engine detected by the exhaust temperature area detecting means decreases. desirable.

Further, according to the present invention, a turbocharger having an exhaust turbine disposed in an exhaust passage and an intake compressor disposed in an intake pipe, an exhaust passage upstream of the exhaust turbine, and the intake compressor A first EGR passage that communicates with a more downstream intake passage; and a first EGR passage.
A first EGR valve disposed in a GR passage, an oxidation catalyst and a particulate filter disposed in an exhaust passage downstream of the exhaust turbine, and an exhaust valve operation for opening an exhaust valve of the same cylinder during an intake stroke A diesel engine exhaust purification device comprising:
An intake shutter disposed in the intake passage upstream of a connection between the EGR passage and the intake passage; and an exhaust shutter disposed in the exhaust passage downstream of the connection between the first EGR passage and the exhaust passage. An exhaust shutter provided, exhaust temperature range detecting means for detecting an exhaust temperature range of the engine, and an exhaust temperature range of the engine detected by the exhaust temperature range detecting means being lower than an active temperature range of the oxidation catalyst. And a control unit for performing control to narrow down one or both of the intake shutter and the exhaust shutter in some cases.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing one embodiment of an exhaust gas purification device for a diesel engine configured according to the present invention. In the embodiment shown in FIG. 1, the same components as those of the conventional exhaust gas purification apparatus shown in FIG. Further, the EGR passage 9 and the EGR valve 11 in FIG. 7 are the first EGR passage 20 and the first EGR valve 21, respectively, in the embodiment shown in FIG. Hereinafter, the points of the embodiment shown in FIG. 1 which are different from the prior art shown in FIG. 7 will be described.

The intake pipe 5 which is upstream of the connection between the intake pipe 5 and the first EGR passage 20 and forms a part of the intake passage
Is provided with an intake shutter 22 for limiting the amount of intake air. The intake shutter 22 is normally kept fully open. Further, an exhaust shutter 23 for restricting the outflow of exhaust gas is provided in the exhaust pipe 20 downstream of the connection between the exhaust pipe 7 and the first EGR passage 20 and constituting a part of the exhaust passage. Have been. The exhaust shutter 23 is held fully open in the normal state, similarly to the intake shutter 22. The intake shutter 22 and the exhaust shutter 23 are connected to a negative pressure tank (not shown).
The opening degree is controlled by controlling the amount of negative pressure supplied according to the operating state by the control means 10.

In the embodiment shown in FIG.
The exhaust pipe 7 downstream of the DPF 7 (more specifically, the DPF 17 and the N
A second EGR passage 24 is provided for connecting the exhaust pipe 7) between the Ox catalyst 14 and the intake passage upstream of the intake compressor 82. The second EGR passage 24 has a second EG
An R valve 25 is provided. The second EGR valve 25 is connected to a negative pressure tank (not shown).
By controlling the amount of negative pressure supplied according to the operation state by the control means 10, the opening and closing thereof are controlled.

In the second EGR passage 24, E
An EGR cooler 23 for cooling the GR gas is provided. The EGR cooler 26 is configured as a heat exchanger surrounding the pipe through which the EGR gas passes, and lowers the exhaust gas to about the temperature of the cooling water by diverting the engine cooling water from the cylinder block and passing it. .

The embodiment shown in FIG. 1 is provided with exhaust temperature range detecting means. Hereinafter, the exhaust temperature region detecting means will be described. The exhaust temperature of the engine is substantially determined mainly by the fuel injection amount (load) supplied to the engine and the engine speed. The control means 10 of the exhaust gas purification apparatus in the illustrated embodiment has an exhaust temperature range map in which the engine speed and the engine load are parameters as shown in FIG. From the injection amount (load), it is detected where the current exhaust gas temperature is. The region shown here refers to the temperature region at the time when the exhaust gas discharged from the cylinder reaches the oxidation catalyst 12, but when the map is defined, the temperature drop until reaching the oxidation catalyst 12 is defined. May be set as the temperature region in the exhaust manifold 4 in consideration of the above.

The boundaries of X, Y, and Z shown in FIG. 2 are set mainly with reference to the test results regarding the exhaust gas temperature of the engine when defining the map and the active temperature region of the oxidation catalyst 12.
X is a region higher than the activation temperature region of the oxidation catalyst 12, Y is a region included in the activation temperature region of the oxidation catalyst 12, and Z is a region lower than the activation temperature region of the oxidation catalyst 12. Further, it is needless to say that the boundary line can be appropriately changed by the user depending on the operating characteristics of the diesel engine employed and the characteristics of the oxidation catalyst 12 employed.
Furthermore, the above-mentioned temperature ranges do not necessarily have to be three,
It is possible to further subdivide or define two areas

Next, the operation of the exhaust gas purifying apparatus in the embodiment shown in FIG. 1 will be described. When the operation of the engine starts, fuel is supplied to the engine by a fuel injection device (not shown). The control means 10 determines the fuel injection amount based on the engine speed signal from the engine speed sensor 15 and the accelerator sensor 16 and the so-called fuel injection amount map shown in FIG.
The control means 10 detects the fuel injection amount at this time as an engine load.

In the exhaust gas purifying apparatus of the embodiment shown in FIG. 1, when the engine load is detected as described above, the control means 10 displays the engine load and the engine rotational speed shown in FIG. The current exhaust temperature range is detected from the exhaust temperature range map. When the current exhaust temperature range is detected in this manner, the control means 10 controls the first EGR valve 21 and the second EG according to the control map shown in FIG. 3 based on the current exhaust temperature range.
R valve 25, intake shutter 22, and exhaust shutter 2
3 is controlled.

First, when the exhaust temperature range is in the active temperature range Y of the oxidation catalyst, the first temperature is determined according to the control map shown in FIG.
The EGR valve 21 is opened, the second EGR valve 25 is closed, and the intake shutter 22 and the exhaust shutter 23 are opened. That is, the control means 10 performs the EGR control during the normal operation.

Next, the case where the exhaust temperature range is higher than the active temperature range of the oxidation catalyst will be described. When the engine speed is high and the load is large, the exhaust gas temperature increases.
This is the exhaust temperature area X in the exhaust temperature area map shown in FIG.
It is. In this case, the exhaust gas temperature exceeds the upper limit of the active temperature range of the oxidation catalyst 12, and the conversion rate for oxidizing NO decreases, so that the PM deposited on the DPF 13 is not burned. Therefore, in order to lower the temperature of the oxidation catalyst 12, the first
Of the EGR valve 21 is throttled. In the illustrated embodiment, the first EGR valve 21 is in the maximum throttle state and is closed. Thus the first
When the EGR valve 21 is closed, the first EGR passage 2
The entire amount of the high-temperature exhaust gas flowing into the intake side through 1 passes through the exhaust turbine 81. As a result, the work of the turbocharger 8 increases, and the amount of intake air supercharged by the intake compressor 82 and flowing into the cylinder increases. Therefore, in the cylinder of the engine, the air becomes excessive (lean) with respect to the fuel injection amount (fuel amount) determined as described above, and the exhaust gas temperature decreases. As a result, the exhaust gas temperature enters the active temperature region Y of the oxidation catalyst 12 in FIG. 2, and the oxidative combustion of the PM collected by the DPF 12 becomes active, so that the filter can be regenerated.

In the exhaust gas purifying apparatus in the illustrated embodiment, the first EGR valve 21 is disposed in the second EGR passage 24 when the first EGR valve 21 is closed in order to ensure the effect of reducing NOx by EGR. The second EGR valve 25 is controlled to open, and the EGR control itself is continued.
In this case, the EGR gas is exhaust gas that has consumed thermal energy after passing through the exhaust turbine 81;
Since the air is cooled by the R cooler 26 and the position where the exhaust gas is recirculated is upstream of the intake compressor 82, that is, in the atmospheric pressure state, the recirculation to the fresh air is performed smoothly, and the absolute intake air amount , The air can be maintained in an excessive state (lean), and there is no significant effect of increasing the exhaust gas temperature.
When the exhaust temperature region is the region X higher than the active temperature region of the oxidation catalyst, the intake shutter 22 and the exhaust shutter 23 change the exhaust temperature region to the active temperature region Y of the oxidation catalyst as shown in the control map of FIG. Open as in normal operation.

Next, the case where the exhaust temperature range is lower than the active temperature range of the oxidation catalyst will be described. When the exhaust temperature range is detected as Z by the exhaust temperature range detecting means,
The control means 10 determines that the exhaust temperature range is lower than the active temperature range of the oxidation catalyst 12, and the same as in the normal operation where the exhaust temperature range is in the active temperature range Y of the oxidation catalyst as shown in the control map of FIG. Then, the first EGR valve 21 is opened and the second EGR valve 25 is closed. In order to raise the exhaust gas temperature, the opening degree of the intake shutter 22 is controlled based on the opening degree map of the intake shutter which is set using the engine speed and the engine load as parameters as shown in FIG. The exhaust shutter 2 based on the exhaust shutter opening map in which the engine speed and the engine load are set as parameters shown in FIG.
3 is controlled. 4 (a) and 4 (b)
In each of the maps shown in FIG. 2, the region of Z in the map used for the exhaust gas temperature region detecting means shown in FIG.
The opening operation of the exhaust shutter is set stepwise.
"3/4 opening" means that it is 1/4 closed with respect to the fully open position, and "1/4 opening" means that it is 3/4 closed.

By controlling the throttle of the intake shutter, fresh intake air is restricted, and the pressure in the intake passage near the outlet of the EGR passage decreases, so that the EGR gas ring flow rate increases. Further, by performing the control of narrowing the exhaust shutter, the exhaust pressure of the connecting portion between the exhaust pipe 5 and the EGR passage 12 which constitutes a part of the exhaust passage increases, and the annular flow rate of the EGR gas increases.

The temperature of the exhaust gas increases as the excess air ratio (λ) approaches 1 during combustion in the cylinder and as the temperature of the intake air increases. Therefore, even in an operation region where the exhaust gas temperature does not reach the active region of the oxidation catalyst 12 under a low rotation speed and a low load state under normal conditions, the above-described control is carried out to increase the intake air temperature, thereby increasing the intake air temperature. And the exhaust gas temperature can be increased to the active temperature region Y. As shown in the maps of FIGS. 4A and 4B, the intake shutter 22 and the exhaust shutter are located in a region where the exhaust temperature region is far from the active temperature region Y of the oxidation catalyst, that is, in a region where the exhaust temperature is lower. The control for narrowing down 23 is performed, and the exhaust gas temperature is further raised.

Although not described in the embodiment shown in FIG. 1, it is also possible to operate the exhaust valve in the same cylinder to open it during the intake stroke. FIG. 5 shows an embodiment of an intake valve operating mechanism 31 for operating the intake valve 30 and an exhaust valve operating mechanism 41 for opening the exhaust valve 40 of the same cylinder during the intake stroke. FIG. The lift curves of the intake valve 30 and the exhaust valve 40 operated by the illustrated intake valve operating mechanism 31 and exhaust valve operating mechanism 41 are shown. The exhaust valve operating mechanism 41 in the embodiment shown in FIG. 5 includes a first exhaust cam lift 421 in which the exhaust cam 42 opens during the exhaust stroke, and a second exhaust cam lift 422, which opens during the intake stroke. Therefore,
The exhaust valve 40 operated by the exhaust valve operating mechanism 41 is opened in the exhaust stroke as shown by the lift curve in FIG. 6, and is also opened for a short time in the intake stroke. In the configuration of FIG. 5, the opening of the exhaust valve in the intake stroke is described as always operating, but the exhaust temperature range is in Z by using a known variable valve mechanism or the like.
In other words, it is possible to perform the exhaust valve opening control during the intake stroke only when it is determined that the exhaust gas is lower than the active region of the oxidation catalyst 17. Can be prevented. As described above, especially when the control for closing the exhaust shutter is performed, the exhaust gas in the exhaust passage is high, so that the exhaust gas flows back into the cylinder as it is, and the exhaust temperature can be increased.

In the illustrated embodiment, the exhaust temperature range is detected by using the exhaust temperature range map shown in FIG. 2. However, this is not necessarily required to directly correspond the temperature parameter value to the region shown in FIG. 2 may be determined in consideration of the exhaust temperature and the active temperature range of the oxidation catalyst. The invention is completely the same even if the OFF is made to correspond. Although the engine speed and the load are input parameters of the exhaust temperature range map of FIG. 2, the load is not limited to the fuel injection amount as described above. Can be used for load detection, and there is no problem in using a substitute value related to the exhaust gas temperature.

Further, in the illustrated embodiment, the exhaust temperature range is detected by the engine speed and the load. However, the present invention is not limited to this. The exhaust temperature range is detected by the exhaust temperature sensor 27 provided directly on the oxidation catalyst 12 of the engine. Is also good.
Also, the oxidation catalyst and DPF are described separately, but DP
It goes without saying that the present invention is also effective in an exhaust gas purification device in which F and the oxidation catalyst are integrally formed.

[0035]

According to the exhaust gas purifying apparatus for a diesel engine according to the present invention, the exhaust gas temperature generated when the so-called continuous regeneration type DPF using the oxidation catalyst and the DPF is employed depends on the operating condition. The problem of deviating from the active temperature range is solved in a wide range regardless of the operating state of the engine.

[Brief description of the drawings]

FIG. 1 is an exhaust gas purification apparatus for a diesel engine configured according to the present invention.

FIG. 2 is an exhaust temperature range map according to the present invention.

FIG. 3 is a control map for each exhaust gas temperature region in the present invention.

FIG. 4 is an opening control map of the intake and exhaust shutters according to the present invention.

FIG. 5 is a structural view of an exhaust / exhaust two-stage cam according to the present invention.

6 is a cam lift curve of intake and exhaust in the configuration of FIG.

FIG. 7 shows a conventional exhaust gas purifying apparatus for a diesel engine.

FIG. 8 shows exhaust gas temperature and PM in a continuous regeneration type DPF.
Graph showing the combustion characteristics of

FIG. 9 is a graph showing the relationship between the engine speed and the load of the exhaust gas temperature of the diesel engine.

FIG. 10 shows a fuel injection amount for calculating a fuel injection amount from an engine speed and an accelerator opening.

[Explanation of symbols]

 2 Engine body 3 Intake manifold 4 Exhaust manifold 5 Intake pipe 6 Air cleaner 7 Exhaust pipe 8 Turbocharger 81 Exhaust turbine 82 Intake compressor 9 Exhaust gas recirculation (EGR) passage 10 Control means (ECM) 11 EGR valve 12 Oxidation catalyst 13 DPF 14 NOx Catalyst 15 Engine rotation speed detection sensor 16 Accelerator sensor 17 Intake air temperature sensor 20 First EGR passage 21 First EGR valve 22 Intake shutter 23 Exhaust shutter 24 Second EGR passage 25 Second EGR valve 26 EGR cooler 27 Exhaust temperature Sensor 30 Intake valve 31 Intake cam 40 Exhaust valve 41 Exhaust valve operating mechanism 42 Exhaust cam 421 First exhaust cam lift 422 Second exhaust cam lift

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01N 3/02 321 F01N 3/02 321H 3/24 3/24 E 3/26 3/26 L F02B 37 / 00F02B 37/00 302F 302 F02D 23/00 F F02D 23/00 JP F02M 25/07 570P F02M 25/07 570 570D 570J F02B 37/00 301F 301G F term (reference) 3G005 DA02 EA16 FA35 GB15 GB11 GB24 GB26 GD GD16 GE09 HA04 HA05 HA12 HA18 JA02 JA13 JA16 JA23 JA24 JA28 JA39 JA42 JA45 JB02 JB05 3G062 AA01 AA05 BA04 BA06 CA06 EA05 ED01 ED03 ED08 FA05 GA04 GA09 GA12 GA13 GA14 GA15 GA22 3G090 AA01 BA01 EA00 DA11 CB00 AA18 AB02 AB05 AB13 BA04 CB07 EA01 EA03 EA08 EA17 HA10 HA15 HA16 HB05 HB06 3G092 AA02 AA17 A A18 DB03 DC03 DC09 DC12 DC15 EA01 EA02 EA22 EC09 FA18 HA06X HA11Z HB01Z HD01Z HD07X HD09X HE01Z

Claims (8)

[Claims] 1. A turbocharger having an exhaust turbine disposed in an exhaust passage and an intake compressor disposed in an intake passage, an exhaust passage upstream of the exhaust turbine, and an intake passage downstream of the intake compressor. A first EGR passage, a first EGR valve disposed in the first EGR passage, an oxidation catalyst and a particulate filter disposed in an exhaust passage downstream of the exhaust turbine. An exhaust gas purification device for a diesel engine, comprising: an exhaust temperature region detecting means for detecting an exhaust temperature region of the engine; and an exhaust temperature region of the engine detected by the exhaust temperature region detecting device, wherein Control means for controlling the throttle of the first EGR valve in a high temperature range. Emissions of exhaust gas purification device. 2. The exhaust temperature range detecting means includes: an engine load detecting means for detecting an engine load; an engine rotational speed detecting means for detecting an engine rotational speed; and an engine load and an engine rotational speed as parameters. The exhaust gas purifying apparatus for a diesel engine according to claim 1, comprising an exhaust gas temperature region map in which an exhaust gas temperature region is set. 3. A second EGR passage communicating between the exhaust passage downstream of the exhaust turbine and the intake passage upstream of the intake compressor, and a second EGR passage provided in the second EGR passage. The EGR valve of the second EGR valve is provided when the exhaust gas temperature range of the engine detected by the exhaust gas temperature range detecting means is higher than the active temperature range of the oxidation catalyst. The exhaust gas purifying apparatus for a diesel engine according to claim 1, wherein the exhaust gas is controlled to open. 4. The exhaust gas purifying apparatus for a diesel engine according to claim 3, wherein cooling means for cooling EGR gas is provided in said second EGR passage. 5. A turbocharger having an exhaust turbine disposed in an exhaust passage and an intake compressor disposed in an intake passage, an exhaust passage upstream of the exhaust turbine, and an intake passage downstream of the intake compressor. A first EGR passage, a first EGR valve disposed in the first EGR passage, an oxidation catalyst and a particulate filter disposed in an exhaust passage downstream of the exhaust turbine. An exhaust shutter disposed in the intake passage upstream of a connection portion between the first EGR passage and the intake passage, the first EGR passage and the exhaust gas. An exhaust shutter provided in the exhaust passage downstream of the connecting portion of the passage, exhaust temperature region detecting means for detecting an exhaust temperature region of the engine,
A control for reducing one or both of the intake shutter and the exhaust shutter when the exhaust temperature range of the engine detected by the exhaust temperature range detection means is lower than the active temperature range of the oxidation catalyst; Means for purifying the exhaust gas of a diesel engine. 6. An exhaust temperature range detecting means includes: an engine load detecting means for detecting an engine load; an engine rotational speed detecting means for detecting an engine rotational speed; and an engine exhaust using the engine load and the engine rotational speed as parameters. 6. The exhaust gas purifying apparatus for a diesel engine according to claim 5, comprising an exhaust gas temperature region map in which a temperature region is set. 7. The control means controls the opening degree of the intake shutter and the exhaust shutter in a stepwise manner as the exhaust temperature area of the engine detected by the exhaust temperature area detecting means decreases. The diesel engine exhaust purification device according to claim 5. 8. A turbocharger having an exhaust turbine disposed in an exhaust passage and an intake compressor disposed in an intake passage, an exhaust passage upstream of the exhaust turbine, and an intake passage downstream of the intake compressor. A first EGR passage, a first EGR valve disposed in the first EGR passage, an oxidation catalyst and a particulate filter disposed in an exhaust passage downstream of the exhaust turbine. An exhaust valve operating mechanism for opening an exhaust valve of the same cylinder during an intake stroke, wherein the exhaust passage is located upstream of a connection between the first EGR passage and the intake passage. An exhaust shutter disposed in the exhaust passage downstream of a connection portion between the first EGR passage and the exhaust passage; Exhaust temperature region detecting means for detecting an air temperature region; and the intake shutter and the exhaust gas when the exhaust temperature region of the engine detected by the exhaust temperature region detecting device is lower than the active temperature region of the oxidation catalyst. Control means for performing control for reducing one or both of the shutters.