JP2003113742A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degradation of the exhaust emission of an internal combustion engine by suppressing clogging of its EGR cooler. SOLUTION: The exhaust emission control device of the internal combustion engine is equipped with an EGR cooler 271, an EGR passage 25 on which the cooler 271 is installed, a detour 272 which puts the suction system 8 of the engine 1 in communication with its exhaust system 18 and where the cooler 271 does not exist on the way, an EGR gas distributing means 276 to distribute the EGR gas to EGR passage 25 and detour 272 on the way of the EGR passage 25 leading from the cooler 271 to one of the suction system 8 and exhaust system 18, and a passage area decreasing means 275 to decrease the area of the passage on the way of the EGR passage 25 leading from the cooler 271 to the other of the systems 8 and 18 and ranging between the cooler 271 and detour 272.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine. [0002] Nitrogen oxides (N
As a method of reducing the amount of Ox), an exhaust gas recirculation (EGR) that recirculates a part of the exhaust gas flowing through the exhaust passage of the internal combustion engine to the intake passage of the internal combustion engine is used.
n) A method using a device has been proposed. [0003] The EGR device uses water vapor (H ₂ O), carbon monoxide (CO), carbon dioxide (CO ₂ ) contained in exhaust gas.
Utilizing the incombustibility and endothermic properties of the inert gas components such as the above, the combustion rate and combustion temperature of the air-fuel mixture in the combustion chamber of the internal combustion engine are reduced, and the amount of nitrogen oxides (NOx) generated during combustion Is to be reduced. [0004] As the above EGR device,
A device including an EGR passage that connects an exhaust passage and an intake passage of the internal combustion engine, and an EGR valve that adjusts a flow rate of exhaust gas (EGR gas) flowing in the EGR passage; and an EGR passage in addition to the EGR passage and the EGR valve. EG for cooling gas
Various types of devices have been proposed, such as a device configured by providing an R cooler in the middle of an EGR passage. For example, Japanese Patent Application Laid-Open No. 11-117815 discloses an EGR cooler, an EGR cooler, a bypass passage for bypassing the EGR cooler, and an EGR cooler and a switching valve for adjusting the amount of EGR gas flowing through the bypass passage.
R devices have been proposed. According to this EGR device, E
By changing the ratio of the EGR gas flowing through the GR cooler and the bypass passage by the switching valve, it becomes possible to supply the EGR gas at a temperature corresponding to the operation state of the internal combustion engine, and it is possible to not only reduce the NOx in the exhaust gas but also reduce the NOx in the exhaust gas. In addition, it is possible to reduce the amount of particulate matter discharged. [0006] By the way, when the exhaust gas is circulated to the EGR cooler when the temperature of the exhaust gas is low, the E
Particulate matter contained in GR gas
PM) may adhere to the inside of the cooler. The PM thus adhered is difficult to remove and causes clogging of the EGR cooler. As a method of preventing the clogging of the EGR cooler, it is conceivable that the switching valve is operated when the temperature of the exhaust gas is low so that the entire amount of the EGR gas flows through the bypass passage. However, for example, even if the switching valve is provided downstream of the EGR cooler and the passage leading to the EGR cooler is completely shut off, the EGR gas flows into the EGR cooler due to the momentum because there is no shield upstream of the EGR cooler. However, there is a case where the air flows inside the EGR cooler.
When such an event is repeated, the EGR cooler
May adhere and clogging of the EGR cooler may occur. When clogging of the EGR cooler or the EGR passage occurs in this way, it becomes difficult to recirculate a desired amount of EGR gas to the intake passage, and as a result, nitrogen oxides (NOx) in the internal combustion engine May not be able to be sufficiently reduced. The present invention has been made in view of the various problems described above, and has as its object to suppress clogging of an EGR cooler and prevent deterioration of exhaust emission of an internal combustion engine. [0010] To achieve the above object, an exhaust gas purifying apparatus for an internal combustion engine according to the present invention employs the following means. That is, an EGR device for recirculating a part of the exhaust gas flowing through the exhaust system of the internal combustion engine to the intake system is provided.
An EGR cooler for cooling EGR gas recirculated through the GR device, an intake system and an exhaust system of the internal combustion engine communicating with each other, an EGR passage interposed by the EGR cooler in the middle, and an intake system and an exhaust system of the internal combustion engine. A detour in which an EGR cooler does not intervene in the middle, and EGR gas distribution means for distributing EGR gas to the EGR passage and the detour in the middle of the EGR passage leading from the EGR cooler to one of an intake system and an exhaust system; A passage area reducing means for reducing a passage area between the EGR cooler and the detour in the middle of the EGR passage leading from the EGR cooler to the other of the intake system or the exhaust system. I do. The most important feature of the present invention is that by providing a means for reducing the passage area of the EGR passage, the EGR passage is provided.
An object of the present invention is to suppress EGR gas from flowing into an EGR cooler when it is desired to circulate all of the gas to a bypass. In the exhaust gas purifying apparatus for an internal combustion engine configured as described above, the EGR gas distribution means circulates the EGR gas mainly to the bypass when the temperature of the exhaust gas is low, while it mainly supplies the EGR gas when the temperature of the exhaust gas is high. Discharge exhaust gas to cooler. By the way, even if the EGR distribution means tries to circulate all the EGR gas to the bypass, a part of the EGR gas may flow into the EGR cooler. Here, when the passage area reducing means reduces the passage area leading to the EGR cooler, the flow resistance of the exhaust gas increases, and the EG flow to the EGR cooler increases.
It is possible to suppress the inflow of the R gas. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of an exhaust gas purifying apparatus for an internal combustion engine according to the present invention will be described below with reference to the drawings. Here, an example in which the exhaust gas purification apparatus for an internal combustion engine according to the present invention is applied to a diesel engine for driving a vehicle will be described. FIG. 1 is a diagram showing a schematic configuration of an engine 1 to which an exhaust emission control device according to the present invention is applied and an intake / exhaust system thereof. The engine 1 shown in FIG. 1 is a water-cooled four-cycle diesel engine having four cylinders 2. The engine 1 has a fuel injection valve 3 for directly injecting fuel into the combustion chamber of each cylinder 2. Each fuel injection valve 3 is connected to a pressure accumulation chamber (common rail) 4 for accumulating fuel up to a predetermined pressure. The common rail 4 communicates with a fuel pump 6 via a fuel supply pipe 5. This fuel pump 6
Is a pump that operates using the rotational torque of the output shaft (crankshaft) of the engine 1 as a driving source. A pump pulley 6a attached to the input shaft of the fuel pump 6 is attached to the output shaft (crankshaft) of the engine 1. And is connected via a belt 7 to the crank pulley 1a. In the fuel injection system thus configured, when the rotational torque of the crankshaft is transmitted to the input shaft of the fuel pump 6, the fuel pump 6 is transmitted from the crankshaft to the input shaft of the fuel pump 6. The fuel is discharged at a pressure corresponding to the rotating torque. The fuel discharged from the fuel pump 6 is
The fuel is supplied to the common rail 4 through the fuel supply pipe 5, accumulated in the common rail 4 to a predetermined pressure, and distributed to the fuel injection valves 3 of each cylinder 2. When a drive current is applied to the fuel injection valve 3, the fuel injection valve 3 opens, and as a result, fuel is injected from the fuel injection valve 3 into the cylinder 2. The opening timing and opening time of the fuel injection valve 3 are controlled by an electronic control unit (ECU) 35.
Is controlled by The ECU 35 is a unit that controls the operating state of the engine 1 according to the operating conditions of the engine 1 and the driver's requirements. Next, an intake branch pipe 8 is connected to the engine 1. Each branch pipe of the intake branch pipe 8 communicates with a combustion chamber of each cylinder 2 through an intake port (not shown). I have. The intake branch pipe 8 is connected to an intake pipe 9,
A compressor housing 15a of a centrifugal supercharger (turbocharger) 15 that operates using heat energy of exhaust gas as a driving source is provided in the middle of the intake pipe 9. In the intake system configured as described above, the intake air flows into the compressor housing 15a through the intake pipe 9. The intake air flowing into the compressor housing 15a is compressed by rotation of a compressor wheel provided in the compressor housing 15a. The intake air compressed in the compressor housing 15a is:
The gas flows through the intake pipe 9 and flows into the intake branch pipe 8. Intake branch pipe 8
Is distributed to the combustion chamber of each cylinder 2 via each branch pipe, and is burned using the fuel injected from the fuel injection valve 3 of each cylinder 2 as an ignition source. On the other hand, an exhaust branch pipe 18 is connected to the engine 1, and each branch pipe of the exhaust branch pipe 18 communicates with a combustion chamber of each cylinder 2 via an exhaust port (not shown). The exhaust branch pipe 18 is connected to a turbine housing 15b of the turbocharger 15.
The turbine housing 15b is connected to one end of an exhaust pipe 19, and the other end of the exhaust pipe 19 has a muffler (not shown).
Leads to. Although diesel engines are economical, particulate matter (hereinafter referred to as PM) represented by soot which is a suspended particulate matter contained in exhaust gas
That. ) Removal is an important issue. For this reason, a technique of providing a particulate filter (hereinafter, simply referred to as a “filter”) for trapping PM in an exhaust system of a diesel engine so that PM is not released into the atmosphere is well known. In the present embodiment, a particulate filter (hereinafter, simply referred to as a filter) 20 carrying an occlusion reduction type NOx catalyst is interposed in the exhaust pipe 19. Next, the filter 20 will be described. FIG. 2 shows the structure of the filter 20. In addition,
2A shows a cross section of the filter 20 in the horizontal direction, and FIG. 2B shows a cross section of the filter 20 in the vertical direction. As shown in FIGS. 2A and 2B, the filter 20 is a so-called wall flow type having a plurality of exhaust passages 50 and 51 extending parallel to each other. These exhaust passages include an exhaust inflow passage 50 whose downstream end is closed by a plug 52 and an exhaust outflow passage 51 whose upstream end is closed by a plug 53. Note that FIG.
In FIG. 5A, the hatched portion indicates the plug 53. Accordingly, the exhaust inflow passages 50 and the exhaust outflow passages 51 are alternately arranged with the thin partition walls 54 interposed therebetween. In other words, the exhaust inflow passage 50 and the exhaust outflow passage 51 are arranged such that each exhaust inflow passage 50 is surrounded by four exhaust outflow passages 51 and each exhaust outflow passage 51 is surrounded by the four exhaust inflow passages 50. The filter 20 is made of a porous material such as cordierite, so that the exhaust gas flowing into the exhaust gas inflow passage 50 flows through the surrounding partition wall 54 as shown by an arrow in FIG. Then, the air flows out into the adjacent exhaust outflow passage 51. In the embodiment according to the present invention, each exhaust inflow passage 5
0 and the peripheral wall surface of each exhaust outflow passage 51, that is, each partition 54
A layer of a carrier made of, for example, alumina is formed on both side surfaces of the substrate and on the inner wall surface of the pores in the partition wall 54, and the storage reduction type NOx catalyst is carried on the carrier. Next, the operation of the storage reduction type NOx catalyst carried on the filter 20 according to the present embodiment will be described. The filter 20 uses, for example, alumina as a carrier and places potassium (K) and sodium (N) on the carrier.
a), selected from alkali metals such as lithium (Li) or cesium (Cs), alkaline earths such as barium (Ba) or calcium (Ca), and rare earths such as lanthanum (La) or yttrium (Y). And a noble metal such as platinum (Pt). The NOx catalyst having the above-described structure is used for the Nx catalyst.
When the oxygen concentration of the exhaust gas flowing into the Ox catalyst is high, nitrogen oxides (NOx) in the exhaust gas are absorbed. On the other hand, when the oxygen concentration of the exhaust gas flowing into the NOx catalyst decreases, the NOx catalyst releases the absorbed nitrogen oxides (NOx). At this time, if reducing components such as hydrocarbons (HC) and carbon monoxide (CO) are present in the exhaust gas, the NOx catalyst converts the nitrogen oxides (NOx) released from the NOx catalyst into nitrogen (N ₂ ) can be reduced. In the exhaust system configured as described above, the air-fuel mixture (burned gas) burned in each cylinder 2 of the engine 1 is discharged to the exhaust branch 18 via the exhaust port, and then from the exhaust branch 18. It flows into the turbine housing 15b of the turbocharger 15. The exhaust gas that has flowed into the turbine housing 15b rotates a turbine wheel rotatably supported in the turbine housing 15b by using thermal energy of the exhaust gas. At this time, the rotational torque of the turbine wheel is transmitted to the compressor wheel of the compressor housing 15a described above. The exhaust gas discharged from the turbine housing 15b flows into a filter 20 via an exhaust pipe 19, where PM in the exhaust gas is collected and harmful gas components are removed or purified. The exhaust gas from which PM has been collected by the filter 20 and from which harmful gas components have been removed or purified flows through the exhaust pipe 19 and is then discharged into the atmosphere via a muffler (not shown). The exhaust branch pipe 18 and the intake branch pipe 8 are connected via an exhaust gas recirculation passage (EGR passage) 25 for recirculating a part of the exhaust gas flowing through the exhaust branch pipe 18 to the intake branch pipe 8. Are in communication. Exhaust gas (hereinafter, referred to as EGR gas), which is constituted by an electromagnetic valve or the like in the middle of the EGR passage 25 and flows through the EGR passage 25 according to the magnitude of applied electric power.
A flow control valve (EGR valve) 26 for changing the flow rate of the air is provided. In the middle of the EGR passage 25, the EGR valve 26
Further upstream, an EGR cooler 27 that cools the EGR gas flowing in the EGR passage 25 is provided. A cooling water passage (not shown) is provided in the EGR cooler 27, and a part of cooling water for cooling the engine 1 circulates. When the engine 1 is operating in the lean burn operation, the air-fuel ratio of the exhaust gas discharged from the engine 1 becomes a lean atmosphere and the oxygen concentration of the exhaust gas becomes high.
Although nitrogen oxides (NOx) contained in the exhaust gas are absorbed by the NOx catalyst, if the lean burn operation of the engine 1 is continued for a long period of time, the NOx absorption capacity of the NOx catalyst is saturated, and Nitrogen oxides (NOx) are released to the atmosphere without being removed by the NOx catalyst. In particular, in a diesel engine such as the engine 1, a mixture having a lean air-fuel ratio is burned in most of the operating region, and the air-fuel ratio of the exhaust gas becomes a lean air-fuel ratio in most of the operating region. , N of the NOx catalyst
Ox absorption capacity is easily saturated. Accordingly, when the engine 1 is operating in the lean combustion mode, the concentration of oxygen in the exhaust gas flowing into the NOx catalyst is reduced and the concentration of the reducing agent is increased before the NOx absorption capacity of the NOx catalyst is saturated. It is necessary to release and reduce nitrogen oxides (NOx) absorbed by the catalyst. As a method of reducing the oxygen concentration in this manner, the amount of soot is increased by adding fuel in the exhaust gas or increasing the amount of recirculated EGR gas so that the amount of soot is increased to a maximum and then further reduced. It is possible to reduce the oxygen concentration of the exhaust gas flowing into the filter 20 and increase the concentration of the reducing agent by increasing the low-temperature combustion or changing the timing or the number of times of fuel injection into the cylinder 2. Here, the low temperature combustion will be described. As described above, conventionally, EGR has been used to suppress the generation of NOx. Since the EGR gas has a relatively high specific heat ratio and requires a large amount of heat to raise the temperature, the combustion temperature in the cylinder 2 decreases as the ratio of the EGR gas in the intake air increases. When the combustion temperature decreases, the NOx generation amount also decreases. Therefore, the higher the EGR gas ratio, the lower the NOx emission amount. However, when the EGR gas ratio is increased, the soot generation starts to increase rapidly at a certain ratio or more. Normal EGR control has a lower EG than soot starts to increase sharply.
It is performed at the R gas ratio. However, when the EGR gas ratio is further increased, the soot sharply increases as described above. However, there is a peak in the generation amount of the soot, and the EGR gas ratio further exceeds this peak. At higher levels, the soot then begins to drop sharply and eventually hardly occurs. This is because when the temperature of the fuel during combustion in the combustion chamber and the surrounding gas temperature are lower than a certain temperature, the growth of hydrocarbons (HC) stops at a stage before reaching soot,
This is because when the temperature of the fuel and the gas around it becomes higher than a certain temperature, the hydrocarbon (HC) grows to soot at a stretch. Therefore, if the combustion during combustion in the combustion chamber and the temperature of the surrounding gas are suppressed to a temperature at which the growth of hydrocarbons (HC) stops halfway, soot will not be generated.
In this case, the endothermic effect of the gas around the fuel when the fuel is burned has a great effect on the temperature of the fuel and the gas around the fuel. By adjusting the gas ratio, it is possible to suppress the generation of soot. The EGR gas ratio when performing low-temperature combustion is as follows:
ECU that has been obtained in advance through experiments etc. and mapped
35 is stored in the ROM 352. Feedback control of the EGR gas amount is performed based on this map. On the other hand, hydrocarbons (HC) whose growth has stopped halfway before reaching soot are converted to NOx carried on the filter 20.
It can be burned by an absorbent or the like. As described above, in low-temperature combustion, hydrocarbons (HC) whose growth has stopped halfway before reaching soot are basically purified by a NOx absorbent or the like. Therefore NOx
When the absorbent or the like is not activated, hydrocarbons (H
Since C) is released into the atmosphere without being purified, it is difficult to use low-temperature combustion. Also, the fuel and the surrounding gas temperature during combustion in the cylinder 2 can be controlled to a temperature lower than the temperature at which the growth of hydrocarbons (HC) stops on the way because of the relatively small engine load that generates a small amount of heat by combustion. Is low. Therefore, in the present embodiment, the low-temperature combustion control is performed when the engine 1 is operated at a low rotation speed and a low load and the NOx storage reduction catalyst carried on the filter 20 reaches the active region. Done. Whether it is within the active region can be determined based on an output signal of an exhaust temperature sensor (not shown) and the like. Thus, in low-temperature combustion, hydrocarbons (HC) as a reducing agent can be supplied to the NOx storage reduction catalyst while suppressing emission of PM represented by soot, and NOx can be reduced and purified. . Further, since heat is generated at this time, it is possible to maintain the temperature of the raised filter 20. On the other hand, the PM collected by the filter is burned and removed by the high-temperature exhaust gas discharged when the engine is operated in a high-speed high-load region. But PM
It takes a certain amount of time to burn PM, and if the operating region of the engine deviates from the high-speed high-load region before PM is completely burned and removed, PM may remain unburned.
Since it is difficult to maintain the operating state of the engine suitable for such PM combustion for a long period of time, the unburned PM gradually accumulates on the filter, causing clogging of the filter. Low-temperature combustion is also effective as one of the methods for effectively removing PM remaining after burning. When the low-temperature combustion is performed, the active oxygen is released by the fuel flowing into the filter 20, whereby the PM is transformed into a substance easily oxidized, and the oxidizable amount per unit time is improved. In addition, by hydrocarbon (HC),
Oxygen poisoning of the catalyst is removed, and the activity of the catalyst is increased, so that active oxygen is easily released. And PM by active oxygen
Is oxidized and burned off. By performing the low-temperature combustion as described above, the concentration of oxygen in the exhaust gas flowing into the filter 20 is reduced, the concentration of the reducing agent is increased, and the nitrogen oxides (NOx) absorbed by the filter 20 are released. In addition, it is possible to oxidize PM. However, the exhaust gas generated by the low-temperature combustion is EGR
When passing through the cooler 27, a large amount of hydrocarbons (HC) contained in the exhaust gas may adhere to the EGR cooler 27 and cause clogging. Thus, E according to the present embodiment
The GR cooler 27 bypasses the EGR gas when the exhaust gas temperature is low and hydrocarbons (HC) or the like may adhere to the EGR cooler 27, thereby suppressing the adhesion of hydrocarbons (HC). Next, the EGR cooler 2 according to the present embodiment
7 will be described. FIG. 3 shows a schematic structure of EGR cooler 27 according to the present embodiment. The EGR cooler 27 includes a cooler 271 and a bypass 272. The cooler 271 is
A plurality of gas passages 273 extending in parallel with each other and alternately
And a cooling water passage 274. Gas passage 273
Is connected to the EGR passage 25, while the cooling water passage 27
Reference numeral 4 is connected to a radiator (not shown) via a cooling water passage (not shown) of the engine 1. Cooler part 27
In the middle of the EGR passage 25 on the side of the exhaust branch pipe 18 as viewed from the side of FIG.
A plate 275 for reducing the passage area of the GR passage 25 is provided. On the other hand, in the middle of the EGR passage 25 on the intake branch pipe 8 side as viewed from the cooler section 271,
A flow path switching valve 276 that rotates by a signal from the ECU 35 is provided at a junction of the detour 1 and the detour 272.
The flow path switching valve 276 can rotate in a range indicated by a dotted line in FIG. 3 and stop at an arbitrary position. In the EGR device according to the present invention, the EGR valve 2
When the valve 6 is opened, the EGR passage 25 becomes conductive,
A part of the exhaust gas flowing through the exhaust branch pipe 18 becomes EGR gas, flows into the EGR passage 25, and is introduced into the EGR cooler 27. Then, the flow path switching valve 276 is
When the EGR passage 25 leading to E.1 is shut off, E
The GR gas flows through the bypass 272. Where EGR
On the inlet side of the cooler 27, the EGR passage 2
Since the area of the flow path 5 is reduced, most of the EGR gas that is going to flow into the cooler unit 271 cannot flow through the location where the path area is reduced, and flows into the bypass 272. On the other hand, when the flow path switching valve 276 blocks the bypass 272, the EGR gas is supplied to the cooler 271.
Is introduced to In the cooler section 271, heat exchange is performed between the EGR gas and the cooling water of the engine 1, and the EGR gas is cooled. Here, the plate 275 becomes a resistance when the EGR gas passes, but due to a pressure difference before and after the plate 275, the EGR gas passes through a gap between the plate 275 and the EGR passage 25 and is introduced into the cooler unit 271. Is done. When the flow path switching valve 276 is stopped at an arbitrary position during rotation, the cooler 271 and the detour 27
The EGR gas can be circulated through both of them. Thus, the EG having a low temperature flowing through the cooler unit 271 is provided.
When the R gas and the high-temperature EGR gas flowing through the detour 272 are mixed, E flowing out of the EGR cooler 27 is mixed.
The temperature of the GR gas changes. Therefore, the flow path switching valve 276
By adjusting the valve opening angle, the temperature of the EGR gas can be adjusted. The EGR gas returned to the intake branch pipe 8 after passing through the EGR cooler 27 is guided to the combustion chamber of each cylinder 2 while being mixed with fresh air flowing from the upstream of the intake branch pipe 8. Here, the EGR gas contains an inert gas component such as water (H ₂ O) or carbon dioxide (CO ₂ ) that does not burn itself and has endothermic properties, such as water (H ₂ O) and carbon dioxide (CO ₂ ). Therefore, if EGR gas is contained in the air-fuel mixture,
The combustion temperature of the air-fuel mixture is lowered, so that the nitrogen oxides (NO
x) is suppressed. Here, in the conventional EGR device, when it is not desired to flow the EGR gas to the cooler portion, the flow path switching valve is switched to flow the EGR gas to the detour. However, a part of the EGR may enter the cooler, and the EGR gas entering the cooler may be cooled, and the PM contained in the EGR may adhere to the wall of the cooler. Was. PM attached in this way
Is difficult to remove, and gradually accumulates to cause a decrease in cooler efficiency and clogging of the cooler. In this regard, in the exhaust gas purifying apparatus for an internal combustion engine according to the present embodiment, the cooler unit 27 is controlled by the flow path switching valve 276.
When the EGR passage 25 leading to 1 is shut off, it is possible to suppress the entry of the EGR gas into the cooler 271 by the plate 275 and suppress the PM from adhering to the cooler 271. According to the present invention, when exhaust gas is circulated through the detour, it is possible to suppress the EGR gas from flowing into the EGR cooler, thereby suppressing clogging of the EGR cooler. Therefore, deterioration of exhaust emission can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing both an engine to which an exhaust gas purification device for an internal combustion engine according to an embodiment of the present invention is applied and an intake / exhaust system thereof. FIG. 2A is a diagram showing a cross section in the transverse direction of a particulate filter. (B) is a figure which shows the longitudinal cross section of a particulate filter. FIG. 3 is a schematic configuration diagram of an EGR cooler. [Description of Signs] 1 ... Engine 1a ... Crank pulley 2 ... Cylinder 3 ... Fuel injection valve 4 ... Common rail 5 ... Fuel supply pipe 6 ... Fuel pump 6a Pump pulley 8 Intake branch 9 Intake tube 15 Turbocharger 15a Compressor housing 15b Turbine housing 18 Exhaust branch 19 Exhaust Pipe 20: particulate filter 25: EGR passage 26: EGR valve 27: EGR cooler 35: ECU

Claims (1)

Claims: 1. An EGR device for recirculating a part of exhaust gas flowing through an exhaust system of an internal combustion engine to an intake system, and cooling EGR gas recirculating the EGR device.
A GR cooler communicates with an intake system and an exhaust system of the internal combustion engine.
An EGR passage in which a cooler is interposed, a detour in which an EGR cooler is not interposed in the middle of communication between the intake system and the exhaust system of the internal combustion engine, EGR gas distributing means for distributing EGR gas to the EGR passage and the bypass, and between the EGR cooler and the bypass in the middle of the EGR passage leading from the EGR cooler to the other of the intake system or the exhaust system. An exhaust gas purifying apparatus for an internal combustion engine, comprising: a passage area reducing means for reducing a passage area of the internal combustion engine.