JP2004190618A - Diesel engine exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promote the temperature rising in a second filter which is arranged at the downstream side of a first filter which collects particulate matter in diesel engine exhaust emission, and whose mesh is finer than that. <P>SOLUTION: Oxidation catalysts 310 and 320 are adhered to foamed gypsum particles 270 of the first filter collecting the particulate matter in the exhaust emission. At the circumference of the foamed gypsum particles 270, a carbon fiber felt 260 whose mesh is finer than the clearance between the foamed gypsum particles 270 is installed between a first inner retainer 250 forming a first communicating hole 251 for communicating the inside and the outside and a second inner retainer 240 which is arranged at the outside and forms a second communicating hole 240 for communicating the inside and the outside. The foamed gypsum particles 270 are brought in contact with the felt 260 via the first communicating hole 251 so as to be subjected to direct heating. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a diesel engine exhaust purification device that captures and burns particulate matter (particulate matter) in exhaust gas discharged from a diesel engine.
[0002]
[Prior art]
Diesel engines have favorable properties, such as low fuel consumption, but emit large amounts of particulate matter. The generation of this particulate matter in a diesel engine is also in a trade-off relationship with the nitrogen oxides (NOx) emitted simultaneously from the diesel engine, and both of them are simultaneously reduced during the combustion process in the diesel engine. It is very difficult to do.
[0003]
In this case, the nitrogen oxide can be post-processed using ammonia, but mounting ammonia on a vehicle is not preferable because of the possibility of leakage. Therefore, in combustion in a diesel engine, priority is given to suppressing the generation of nitrogen oxides which are difficult to perform after-treatment on a vehicle. In order to reduce particulate matter, the particulate matter contained in the exhaust gas discharged from the diesel engine is captured by a filter provided in the middle of the exhaust system, and the filter is clogged. The particulate matter is burned at a predetermined frequency so as not to occur.
[0004]
In the combustion of the particulate matter, the particulate matter does not burn unless it is at a high temperature of about 600 ° C. or more, and the exhaust temperature is 200 ° C. near the silencer during normal running such as running in the city. Since there is almost no increase, the oxidation catalyst and electric heater are used to promote the combustion of the particulate matter captured by the filter section.
[0005]
In such a conventional exhaust gas purifying device for a diesel engine, exhaust gas flowing into a cylindrical housing is disposed radially outside the inner pipe from an outlet hole provided in an outer peripheral wall of the inner pipe. When flowing into the first filter section, the particulate matter in the exhaust gas is captured by the first filter section and is appropriately heated by an electric heater and burned to form ash. The exhaust gas that has passed through the first filter section flows into the second filter section having a finer mesh provided downstream of the first filter section, and particulate matter or the like that has not been captured by the first filter section is captured here. (See Patent Document 1).
[0006]
[Patent Document 1]
JP-A-2002-256843 (FIG. 1)
[0007]
[Problems to be solved by the invention]
In such a conventional exhaust gas purifying apparatus for a diesel engine, a second filter section is provided downstream of the first filter section so as to supplement finer particulate matter which could not be supplemented by the first filter section. However, even if the particulate matter in the first filter section is ignited by the electric heater, the temperature on the downstream side does not rise so much, and the particulate matter captured in the second filter section is difficult to burn. There was a problem.
The present invention has been made in order to solve the above-mentioned problem, and a second filter unit which is disposed downstream of the first filter unit for capturing particulate matter in exhaust gas and has a finer mesh than the first filter unit. It is an object of the present invention to provide a diesel engine exhaust purification device capable of promoting the temperature rise of a diesel engine.
[0008]
[Means for Solving the Problems]
In the exhaust gas purifying apparatus for a diesel engine according to the present invention, the exhaust inlet portion into which the exhaust gas discharged from the diesel engine flows and the exhaust outlet portion from which the exhaust gas flows out are provided inside the cylindrical outer drum. A first filter portion disposed inside the outer drum, the first filter portion being disposed inside the outer drum and capturing particulate matter in the exhaust gas flowing from the exhaust inlet portion; A combustion promoting section disposed inside and promoting the combustion of the particulate matter captured by the first filter section, and a first communication hole disposed downstream of the first filter section and communicating between the inside and outside are formed. A first fill is provided between a first inner retainer and a second inner retainer disposed downstream of the first inner retainer and having a second communication hole communicating between the inside and the outside. A second filter portion holding a second filter material having a finer mesh than the portion, and the first filter material of the first filter portion is connected to the second filter portion through the first communication hole of the first inner retainer. It is characterized in that it comes into contact with the second filter material.
[0009]
In the exhaust gas purifying apparatus for a diesel engine according to the present invention, the first communication hole of the first inner retainer has a larger opening area than the second communication hole of the second inner retainer. It is characterized by:
[0010]
In the exhaust gas purifying apparatus for a diesel engine according to the third aspect of the present invention, the second filter material is disposed between the first inner retainer and the second inner retainer in a non-compressed state. Exhaust flowing from one communication hole can flow into another second communication hole near the second communication hole that is the shortest distance from the first communication hole via the second filter material. Features.
[0011]
According to a fourth aspect of the present invention, in the exhaust gas purifying apparatus for a diesel engine, the first filter material is formed of a group of pellets capable of supplementing the particulate matter.
[0012]
According to a fifth aspect of the present invention, in the exhaust purification device for a diesel engine according to the present invention, the combustion promoting portion is an oxidation catalyst, and is attached to a surface of the first filter material.
[0013]
According to a sixth aspect of the present invention, there is provided an exhaust gas purification apparatus for a diesel engine, wherein the oxidation catalyst includes a noble metal-based oxidation catalyst and a base metal-based oxidation catalyst.
[0014]
The exhaust gas purifying apparatus for a diesel engine according to the present invention is characterized in that the second filter material is formed in a felt shape in which fibers are combined.
[0015]
According to an eighth aspect of the present invention, in the exhaust gas purifying apparatus for a diesel engine, the fiber is made of a carbon-based material.
[0016]
According to a ninth aspect of the present invention, in the exhaust gas purifying apparatus for a diesel engine according to the present invention, the first filter material of the first filter portion has a total capacity larger than that of the second filter material of the second filter portion. Features.
[0017]
In the exhaust gas purifying apparatus for a diesel engine according to the present invention, the second filter portion is disposed radially outside the first filter portion, and the first exhaust gas flows through the outer peripheral portion of the first filter portion. It is characterized in that it flows into the filter section.
[0018]
【The invention's effect】
In the exhaust gas purifying apparatus for a diesel engine according to the present invention, the exhaust gas discharged from the diesel engine is guided from the exhaust gas inlet to the first filter section in the exhaust gas purifying apparatus, and is included in the exhaust gas. Particulate matter is attached to the first filter material and captured, and then the remaining exhaust gas flows into the second filter portion and is captured by the second filter material that has failed to be captured by the first filter material. Spills out of the department. Then, the supplemented particulate matter is appropriately ignited in the combustion promoting unit to be converted into carbon dioxide and ash. At this time, the particulate matter of the first filter section exposed to the high-temperature exhaust gas starts to ignite and the temperature rises, but at least a part of the first filter material is in contact with the second filter material. As a result, the temperature rise of the second filter material is promoted more than in the case where there is no contact, and the particulate matter supplemented here is burned. As a result, the particulate matter is captured by the first filter unit while suppressing excessive flow resistance to the exhaust gas, and the finer particulate matter that could not be captured by the first filter unit is replaced by the second filter unit having a finer mesh. And can be easily burned, and the clogging can be prevented.
[0019]
In the exhaust gas purifying apparatus for a diesel engine according to the present invention, the first communication hole of the first inner retainer has a larger opening area than the second communication hole of the second inner retainer. At least a part of the first filter material easily comes into contact with the second filter material easily through the one communication hole, and the exhaust gas that has flowed vigorously from the first communication hole narrows the flow passage area by the second communication hole. As a result, the exhaust gas enters the region outside the passage that linearly connects the first and second communication holes of the second filter material, and the second filter material supplements the particulate matter in the exhaust with the second filter material. It becomes possible to burn, and the second filter material can be used efficiently.
[0020]
In the exhaust gas purifying apparatus for a diesel engine according to the third aspect of the present invention, the second filter member is disposed between the first inner retainer and the second inner retainer in a non-compressed state. A part of the exhaust gas flowing from the communication hole flows through the second filter material into another second communication hole near the second communication hole which is the shortest distance from the first communication hole, 1. Exhaust gas can easily enter a region outside a passage that linearly connects the second communication holes, and the second filter material can capture and burn particulate matter in the exhaust gas by the second filter material. As a result, the second filter material can be used efficiently.
[0021]
In the exhaust gas purifying apparatus for a diesel engine according to the fourth aspect of the present invention, since the first filter material is formed from a group of pellets capable of supplementing particulate matter, the first filter material is inexpensive as compared with a honeycomb type filter. Not only can it be manufactured, but also a part of the pellets of the first filter material can be easily projected outward from the first communication hole to be in contact with the second filter material.
[0022]
In the exhaust gas purifying apparatus for a diesel engine according to the fifth aspect of the present invention, since the combustion promoting portion is attached to the surface of the first filter material as an oxidation catalyst, the entire first filter portion can be easily ignited. The volume can be set smaller than when an electric heater is used for the combustion promoting section.
[0023]
In the exhaust gas purifying apparatus for a diesel engine according to the present invention, the oxidation catalyst has a noble metal-based oxidation catalyst and a base metal-based oxidation catalyst. It is possible to burn particulate matter by the catalytic action of the noble metal oxidation catalyst at a much lower temperature range, and this combustion raises the temperature and reduces the catalytic action of the noble metal oxidation catalyst. Even in the temperature range, the catalytic action of the base metal-based oxidation catalyst makes it possible to burn the particulate matter / matter in a temperature range lower than the normal combustion temperature.
[0024]
In the exhaust gas purifying apparatus for a diesel engine according to the present invention, since the second filter material is formed in a felt shape in which fibers are combined, the second filter material having a finer mesh than the first filter portion is formed by the first filter member. It is possible to arrange the non-compressed state between the inner retainer and the second inner retainer easily and inexpensively as compared with a pellet or the like.
[0025]
In the exhaust gas purifying apparatus for a diesel engine according to the present invention, since the fibers are made of a carbon-based material, the temperature of the fibers can be easily raised by heat from the first filter portion and the exhaust gas. It becomes possible to burn the fine particle supplemented with fiber.
[0026]
In the exhaust gas purifying apparatus for a diesel engine according to the ninth aspect of the present invention, the total capacity of the first filter material is made larger than that of the second filter material having a finer mesh. And combustion can be promoted.
[0027]
In the exhaust gas purifying apparatus for a diesel engine according to the present invention, the second filter portion is disposed radially outside the first filter portion, and the exhaust gas passes through the outer peripheral portion of the first filter portion. Since it is made to flow into the part, compared with the case where the exhaust gas flows along the axial direction of the exhaust gas purification device, it is easy to set a large flow area of the exhaust gas, and it is possible to reduce the flow resistance of the exhaust gas, Clogging over the entire distribution area can be suppressed.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional side view of an exhaust gas purifying apparatus 100 for a diesel engine as an embodiment of the present invention.
The exhaust gas purification device 100 has a cylindrical housing 110, and the housing 110 incorporates a filter unit 200 and an oxidation catalyst 300 (combustion promoting unit).
[0029]
The housing 110 is made of metal and has a cylindrical outer drum 111 having both ends opened, and an inlet-side end attached to the opening 111a on the upstream side of the outer drum 111 to close the opening 111a. -It has a plate 112 and an outlet end plate 113 attached to the opening 111b on the downstream side of the outer drum 111 and closing the opening 111b.
[0030]
In the inlet-side end plate 112, an inlet pipe (exhaust inlet) 114 is made to pass through a through hole 112 a formed in the center portion. An intermediate portion of the pipe 114 is fixed by welding. On the other hand, the outer peripheral portion of the inlet end plate 112 is fitted into the opening 111a on the upstream side of the outer drum 111, and is fixed to each other by welding.
[0031]
The inlet pipe 114 is combined with a flange 115 fixed to the upstream end portion and a flange (not shown) of an exhaust pipe (not shown) on the diesel engine side with a gasket interposed therebetween, and bolts ( (Not shown). Further, the downstream end portion of the inlet pipe 114 is made to pass through a through hole 116a formed at the center of the disk-shaped inlet-side separate plate 116, and the inner periphery of the through-hole 116a of the inlet-side separate plate 116 is formed. It is fixed to the part by welding. The outer peripheral portion of the inlet-side separate plate 116 is fixed by welding to a position downstream of the inlet-side end plate 112 of the outer drum 111.
[0032]
A collar 117 that penetrates the inlet-side end plate 112 and the inlet-side separate plate 116 at a position above the center line in the figure is fixed. The temperature sensor 400 is inserted inside the collar 117. The temperature sensor 400 is for detecting the temperature inside the filter section 200, and the detection portion is extended to the inside of the filter section 200.
[0033]
Downstream of the inlet pipe 114, an inner pipe 500, which is coaxial with and slightly larger in diameter, extends toward the downstream side in the axial direction. On the outer peripheral wall of the inner pipe 500, a number of outflow holes 510 drilled in the radial direction are provided (only one outflow hole 510 is drawn in FIG. 1 for the sake of convenience in order to make the drawing easy to see). Then, the inside and the outside of the outer peripheral wall of the inner pipe 500 are communicated with each other. Although the upstream side of the inner pipe 500 is left open, a circular plate 520 is attached to the inner peripheral portion at the downstream end so that exhaust gas does not flow out from the downstream end in the axial direction. Is closed.
[0034]
The inner peripheral portion of the upstream separator 530 is fixed to the outer peripheral portion of the upstream end of the inner pipe 500 by welding, and the outer peripheral portion of the upstream separator 530 is located downstream of the inlet-side separate plate 116. Is in contact with the inner peripheral surface of the outer drum 111. The upstream separator 530 is formed so that the exhaust gas flowing from the inlet pipe 114 does not directly flow into the filter unit 200. As a result, the exhaust gas flowing from the inlet pipe 114 is Everything flows into the inner pipe 500.
[0035]
Similarly, an inner peripheral portion of the downstream separator 540 is fixed to an outer peripheral portion of the downstream end of the inner pipe 500 by welding. A plurality of communication holes 545 are formed on the periphery of the downstream separator 540 so that exhaust gas flowing out of the filter unit 200 flows to the outlet pipe 119. The outer peripheral portion of the downstream separator 540 is configured to abut on the inner peripheral surface of the outer drum 111 at a position downstream of the upstream separator 530.
In this manner, the inner pipe 500 is supported by the outer drum 111 of the housing 110 by the downstream separator 540 and the upstream separator 530.
[0036]
The diameter of the downstream separator 540 is set slightly smaller than that of the upstream separator 530, and when the inner pipe 500 thermally expands in the axial direction, the downstream separator 540 slides with respect to the outer drum 111. The difference in thermal expansion is absorbed, and conversely, when the temperature cools and contracts, the downstream separator 540 slides against the outer drum 111 to absorb the difference in contraction at that time.
[0037]
A downstream holding plate 220 slidable with respect to the inner pipe 500 and supported on the outer periphery of the inner pipe 500 is provided at a position away from the downstream separator 540 by a predetermined distance on the upstream side of the inner pipe 500. Provided. As a result, an upstream expansion chamber 600 is formed between the downstream holding plate 220 and the downstream separator 540.
[0038]
The plate 210 with the upstream cushion sheet is held at the upstream end portion of the outer peripheral wall of the inner pipe 500 in a state where the plate 210 with the upstream cushion sheet is in contact with the surface on the downstream side of the upstream separator 530. Similarly, the plate 230 with the downstream cushion sheet is held at the downstream end portion of the outer peripheral wall of the inner pipe 500 in a state where the plate 230 with the downstream cushion sheet is in contact with the upstream side surface of the downstream holding plate 220.
In addition, the detection part of the temperature sensor 400 penetrates the upstream separator 530 and the plate 210 with the upstream cushion sheet, and the detection part enters the inside of the filter part 200.
[0039]
Each of the outer peripheral portions of the upstream-side cushion sheet-equipped plate 210 and the downstream-side cushion sheet-equipped plate 230 has a first inner retainer 250 in which a metal plate provided with a large number of holes, such as punch metal, is formed in a cylindrical shape. It is connected to each end of the second inner retainer 240 disposed outside.
[0040]
The first inner retainer 250 is spaced radially outward from the inner pipe 500 by a predetermined distance, and the second inner retainer 240 is disposed radially outward and radially inward of the outer drum 111. I have.
A cylindrical space formed between the outer peripheral surface of the second inner retainer 240 and the inner peripheral surface of the outer drum 111 communicates with the upstream expansion chamber 600.
[0041]
In the space between the inner peripheral surface of the first inner retainer 250 and the outer peripheral surface of the inner pipe 500 and between the plate 210 with the upstream cushion sheet and the plate 230 with the downstream cushion sheet, a fine hole is provided. A large number of pellet-shaped foamed stone particles (first filter material) 270 having the following are filled. The foam stone particles 270 are formed so as to be trapped by adhering particulate matter in the exhaust gas to the surface and the fine pores.
[0042]
In addition, the upstream separator 530, the downstream holding plate 220, the plate 210 with the upstream cushion sheet, the plate 230 with the downstream cushion sheet, and the foam stone 270 constitute the first filter unit of the filter unit 200 of the present invention. I do.
[0043]
Then, on the surface of the foamed stone bone 270, there is an oxidation composed of a noble metal based catalyst such as platinum which exhibits an oxidation catalyst function in a low temperature range and a base metal based catalyst such as nickel which exhibits an oxidation catalyst function in a high temperature range. The catalyst 300 is permeated and adhered in a mixed state.
[0044]
On the other hand, a felt (second filter material) 260 combining carbon fibers is inserted between the first inner retainer 250 and the second inner retainer 240 outside the first inner retainer 250. The mesh of the felt 260 is set finer than the gap formed between the foamed stone grains 270. In addition, the total capacity of the felt 260 is set to be smaller than the total capacity of the aggregate of the foam stone bone particles 270.
The felt 260, the first inner retainer 250, and the second inner retainer 240 constitute a second filter unit of the filter unit 200 of the present invention.
[0045]
FIG. 2 is a cross-sectional view schematically showing a part of the second filter unit in an enlarged manner.
In the figure, a noble metal-based oxidation catalyst 310 such as platinum and a base metal-based oxidation catalyst 320 such as nickel are adhered to the surface of the foam stone bone 270.
The first inner retainer 250 disposed inside has a large number of first communication holes 251 communicating the inside and outside thereof, and the second inner retainer 240 similarly disposed outside has the same inside and outside. A large number of second communication holes 241 communicating with each other are formed.
[0046]
Here, the first communication hole 251 is capable of receiving at least a part of the foamed stone 270, and a portion protruding outward from the first communication hole 251 can be in contact with the felt 260 made of carbon fiber. The second communication hole 241 of the second inner retainer 240 is set to have an opening area smaller than that of the first communication hole 251.
[0047]
In FIG. 2, some of the carbon fibers constituting the felt 260 are in contact with the outer surface of the first inner retainer 250 and the inner surface of the second inner retainer 240, but the felt 260 is not compressed. In this state, it is arranged between first inner retainer 250 and second inner retainer 240.
[0048]
That is, the felt 260 is formed by combining carbon fibers by three-dimensional knitting or the like, so that exhaust gas can flow between the carbon fibers in the front-back, side-to-side, and oblique directions in FIG. Exhaust air can flow in the front-back, side-to-side, and oblique directions in the figure even through a gap formed between the outer surface of the retainer 250 and the inner surface of the second inner retainer 240. As a result, it is set so that the exhaust gas flowing from the first communication hole 251 can not only go to the nearest second communication hole 241 but also go to the second communication hole 241 that is further laterally away therefrom. It is.
[0049]
Returning to FIG. 1, the outer peripheral portion of the downstream end plate 113 is fitted into the opening 111b at the downstream end of the outer drum 111, and this portion is fixed to each other by welding. An intermediate portion of an outlet pipe (exhaust outlet) 118 is made to pass through a through hole 113a formed in the central portion of the downstream end plate 113, and an inner periphery of the through hole 113a of the downstream end plate 113 is provided. An intermediate portion of the outlet pipe 118 is fixed to the portion by welding.
[0050]
A flange 119 is fixed to the downstream end of the outlet pipe 118, and this flange 119 sandwiches a gasket (not shown) between a flange (not shown) of a downstream exhaust pipe (not shown). It is fixed by bolts (not shown) in the state.
[0051]
The upstream end of the outlet pipe 118 is fixed to the inner peripheral portion of the through hole 120a of the disc-shaped downstream separate plate 120 by welding. The outer peripheral portion of the downstream-side separate plate 120 is in contact with the inner peripheral surface of the outer drum 111. The downstream-side separate plate 120 is formed so as not to allow exhaust gas to pass therethrough, and is configured so that all exhaust gas flowing out of the filter unit 200 flows into the outlet pipe 118.
[0052]
A downstream expansion chamber 700 having a larger volume than the upstream expansion chamber 600 is formed between the downstream separate plate 120 and the downstream separator 540, and the downstream expansion chamber 700 is connected to the upstream expansion chamber 600 by the downstream separator 600. The communication is made via communication holes 545 of the 540.
[0053]
Next, the operation of the exhaust purification device 100 for a diesel engine will be described.
The exhaust gas discharged from the diesel engine flows into the exhaust purification device 100 from the inlet pipe 114 through an upstream exhaust pipe (not shown). All the exhaust gas flowing from the inlet pipe 114 flows into the inner pipe 500. Since the downstream end of the inner pipe 500 is blocked by the plate 220, the exhaust gas flowing into the inner pipe 500 flows radially outward from the many outflow holes 510 provided in the outer peripheral wall of the inner pipe 500. It flows out and flows into the inside of the filter unit 200. In this case, since the speed of the exhaust gas is high, the exhaust gas collides with the circular plate 520 and then flows out more radially outward from the outlet hole 510 on the downstream side of the inner pipe 500 than on the upstream side of the inner pipe 500.
[0054]
As the exhaust gas flows radially outward through the filter unit 200, the particulate matter contained in the exhaust gas adheres to the surface of the foam stone 270 in the first filter unit, They are trapped by penetrating into the micropores of the bone grain 270. The remaining exhaust gas, which has captured most of the particulate matter, further passes through the first communication hole 251 of the first inner retainer 250 and the finer particulate matter at the carbon fiber felt 260 of the second filter portion. Is captured, and then flows radially outward from the second communication hole 241 of the outer second inner retainer 240. In this case, as a result of the flow of exhaust gas described above, the amount of particulate matter supplemented by the foamed stone bone 270 and the felt 260 increases in a portion corresponding to the downstream side of the inner pipe 500.
[0055]
The exhaust gas that has flowed out of the filter unit 200 in this way flows into the upstream expansion chamber 600, where it expands to reduce its momentum, thereby reducing exhaust noise. Then, the gas again flows into the wider expansion chamber 700 on the downstream side through the communication hole 545 of the downstream separator 540, where it expands again to further reduce its momentum, and the exhaust noise is further reduced. Through the atmosphere.
[0056]
When the exhaust temperature rises due to the high-speed operation or high-load operation of the diesel engine, the particulate matter captured by the foam stone 270 becomes lower due to the noble metal oxidation catalyst attached to the surface of the foam stone 270. Start burning at temperature. This combustion often starts at the downstream and inner portion of the group of effervescent bone grains 270 that is more likely to become hotter. By this combustion, the foam stone particles 270 on the outer side are also heated and burn to become high temperature. However, since the foam stone particles 270 on the outer peripheral side are in contact with the carbon fiber felt 260, the felt 260 is removed. Also directly heating.
[0057]
As a result, the felt 260 can also reach a high temperature early, and the combustion of the particulate matter captured by the first and second filter units is promoted. As the temperature further increases, the catalytic effect of the noble metal-based oxidation catalyst decreases, but this time, the base metal-based oxidation catalyst starts to work, and the particulate matter further burns. In this way, it becomes possible to burn harmful particulate matter into ash or carbon dioxide and prevent clogging of the filter unit 200.
[0058]
On the other hand, each component of the exhaust gas purification device 100 exposed to the high temperature thermally expands, but the amount of thermal expansion differs depending on the site and the material. In particular, the filter section 200 and the inner pipe 500 are exposed to a high temperature and have significantly different amounts of thermal expansion. Further, the temperature may be different inside and outside the radial direction depending on the combustion state.
If the inner pipe 500 thermally expands as described above, the downstream separator 540 moves with the expansion of the inner pipe 500 in the axial direction (right side in the figure). In this case, the downstream separator 540 is used. Of the outer drum 111 slides in the axial direction along the inner peripheral surface of the outer drum 111 to absorb the difference in thermal expansion therebetween, so that distortion due to this is reduced.
[0059]
On the other hand, the filter section 200 also thermally expands with a different thermal expansion amount from the inner pipe 500, and the holding plate 220 holding the oxidation catalyst 300 and the foamed stone 270 also moves. Since it slides with respect to the pipe 500 to absorb the difference in thermal expansion between them, it is possible to suppress the occurrence of large distortion in the filter section 200.
[0060]
As described above, the exhaust gas purifying apparatus 100 for a diesel engine according to the embodiment of the present invention has the filter unit 200 formed by combining the first filter unit including the foamed stone bone 270 and the carbon fiber disposed downstream of the first filter unit. Since the second filter section made of the second filter section 260 is used, and the foam stone 270 protrudes from the first communication hole 251 of the first inner retainer 250 and comes into contact with the carbon fiber felt 260, the felt 260 can be quickly moved. It is possible to heat to a high temperature, and it becomes possible to capture and burn fine particulate matter that has failed to be captured by the foam stone 270 with the felt 260.
[0061]
In this case, since the total volume of the first filter section made of the foamed stone bone particles 270 is made larger than that of the second filter section made of the felt 260, fine particles are removed from the large particulate matter without excessively increasing the flow resistance of the exhaust gas. It becomes possible to supplement and burn even particulate matter. And since the foamed stone bone 270 is used as the first filter material, not only can it be manufactured inexpensively, but also at least a part thereof can be easily projected from the first communication hole 251 and brought into contact with the felt 260.
[0062]
Further, since the noble metal-based oxidation catalyst 310 and the base metal-based oxidation catalyst 320 are used as the oxidation catalyst 300, the combustion of particulate matter by the oxidation catalyst 300 in a wide temperature range from a low temperature range to a higher temperature range. Becomes possible. Moreover, if the oxidation catalyst 300 is attached to the surface of the foam stone 270, the oxidation catalyst 300 comes into contact with the particulate matter supplemented by the foam stone 270, and the catalytic reaction is accelerated. At the same time, the exhaust emission control device 100 can be made compact.
[0063]
Note that, in place of the above-described embodiment, the following changes and modifications may be made in the present invention.
That is, the first filter material is not limited to the foam stone 270, and a different filter material may be used. Similarly, the second filter material is not limited to the carbon fiber felt 260, and a different filter material may be used.
Further, the filter unit 200 is formed in a cylindrical shape, but is not limited to this, and may have another shape. Good.
Further, an electric heater or the like may be used instead of the oxidation catalyst 300 as the combustion promoting unit. The combustion promoting unit may be provided upstream of the filter unit 200, instead of being built in the filter unit 200.
[0064]
Further, in the present invention, the inlet side end plate 112 and the outlet side end plate 113 are fixed to the outer drum 111 by welding, but at least one of them is connected by a flange and a bolt, and the inner side is removed by removing these. The pipe 500 and the filter section 200 may be detachable from the outer drum 111 so that the filter section 20 can be cleaned or replaced. In this case, the separator is fixed with a bolt or the like so that the separator can be removed from the inner pipe 500, and the filter unit 200 can be pulled out in the axial direction from the inner pipe 500, or the filter unit 200 can be opened halfway so as to have a radius. It is good to be able to remove to the outside of the direction.
[Brief description of the drawings]
FIG. 1 is a cross-sectional side view of an exhaust gas purification device for a diesel engine according to an embodiment of the present invention. FIG. 2 is a front view of a part of a second filter unit of the exhaust gas purification device for a diesel engine according to the embodiment of the present invention. Enlarged cross-sectional view from the viewpoint
REFERENCE SIGNS LIST 100 Exhaust gas purification device 110 Housing 111 Outer drum 112 Inlet end plate 113 Outlet end plate 114 Inlet pipe 116 Upstream separate plate 118 Outlet pipe 120 Downstream separate plate 200 Filter unit 210 Upstream cushion Plate with seat 220 Holding plate 240 Second inner retainer 241 Second communication hole 250 First inner retainer 251 First communication hole 260 Felt 230 Downstream plate with cushion sheet 300 Oxidation catalyst 310 Precious metal-based oxidation catalyst 320 Base metal-based Oxidation catalyst 400 Temperature sensor 500 Inner pipe 510 Outlet 530 Upstream separator 540 Downstream separator 545 Communication hole 600 Upstream expansion chamber 700 Downstream expansion chamber 00 exhaust gas purification apparatus 900 interfere pipe

Claims (10)

A housing in which an exhaust inlet portion into which exhaust gas discharged from the diesel engine flows and an exhaust outlet portion from which the exhaust gas flows communicate with the inside of the cylindrical outer drum;
A first filter portion that is disposed inside the outer drum and has a first filter material that captures particulate matter in the exhaust gas flowing from the exhaust gas inlet portion;
A combustion promoting section disposed inside the outer drum, for promoting combustion of the particulate matter captured by the first filter section;
A first inner retainer disposed downstream of the first filter portion and having a first communication hole communicating the inside and the outside; and a second communication disposed downstream of the first inner retainer and communicating the inside and the outside. A second filter portion in which a second filter material having a mesh finer than the first filter portion is held between a second inner retainer having a hole formed therein, and an exhaust gas purification apparatus for a diesel engine,
A diesel engine, wherein the first filter material of the first filter portion contacts the second filter material of the second filter portion via the first communication hole of the first inner retainer. -Engine exhaust purification device. 2. The diesel engine according to claim 1, wherein the first communication hole of the first inner retainer has an opening area larger than that of the second communication hole of the second inner retainer. 3. Exhaust gas purification device. The second filter material is disposed in a non-compressed state between the first inner retainer and the second inner retainer, and the exhaust gas flowing from the first communication hole is provided in the first communication hole. 3. The flow passage through the second filter material to another second communication hole near the second communication hole, which is the shortest distance from the second communication hole. 4. Diesel engine exhaust purification equipment. The exhaust gas purification device for a diesel engine according to any one of claims 1 to 3, wherein the first filter material is formed from a group of pellets capable of supplementing the particulate matter. The exhaust purification device for a diesel engine according to any one of claims 1 to 4, wherein the combustion promoting unit is an oxidation catalyst, and is attached to a surface of the first filter material. The exhaust gas purifying apparatus for a diesel engine according to claim 5, wherein the oxidation catalyst includes a noble metal-based oxidation catalyst and a base metal-based oxidation catalyst. The exhaust purification device for a diesel engine according to any one of claims 1 to 6, wherein the second filter material is formed in a felt shape in which fibers are combined. The exhaust purification device for a diesel engine according to claim 7, wherein the fibers are made of a carbon-based material. 9. The method according to claim 1, wherein the first filter material of the first filter unit has a total capacity larger than that of the second filter material of the second filter unit. An exhaust purification device for a diesel engine as described. The said 2nd filter part is arrange | positioned in the radial direction outer side of the said 1st filter part, The said exhaust gas flows into the said 1st filter part via the outer peripheral part of the said 1st filter part, The Claims characterized by the above-mentioned. An exhaust gas purifying apparatus for a diesel engine according to any one of claims 1 to 9.

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