JP2009091982A - Exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device capable of suppressing heat radiation from a casing which accommodates a particulate filter. <P>SOLUTION: The device is equipped with an exhaust inflow part 50 into which exhaust of an engine 1 flows; a first casing 46 having a downstream end opening 52 through which the flowed in exhaust flows out; a second casing 48 which is formed in a cylindrical shape with both ends open to accommodate a particulate filter 38, whose upstream end opening 54 is detachably coupled to the downstream end opening 52 of the first casing 46 via a first flange 60 and second flange 62, and includes an exhaust outflow part 58 through which exhaust passing through the particulate filter 38 flows out in a side wall part 56 situated on the downstream side from the particulate filter 38; and a lid member 70 which is detachably mounted to the second casing 48 via a third flange 72 and fourth flange 74 and which blocks a downstream end opening 68 of the second casing 48. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust emission control device that purifies engine exhaust, and more particularly to an exhaust emission control device that includes a particulate filter that collects particulates contained in engine exhaust.

Conventionally, a particulate filter is provided in the exhaust passage of an engine such as a diesel engine, and particulates contained in the exhaust discharged from the engine are collected by the particulate filter so that the particulates are not released into the atmosphere. Technology is known.
In the particulate filter, the exhaust resistance increases as the collected particulate matter accumulates in the particulate filter. For this reason, the particulate filter is forcibly regenerated as appropriate, and the accumulated particulate matter is forcibly incinerated. Play the curate filter.

  On the other hand, in addition to such particulates, a material called ash caused by engine oil, wear powder generated in the engine, or particulate ash remaining by forced regeneration, accumulates on the particulate filter along with the particulates. To go. However, this ash, unlike the particulates, remains in the particulate filter without being incinerated by forced regeneration of the particulate filter. If the amount of ash remaining in the particulate filter increases, not only will there be a problem of increasing exhaust resistance in the particulate filter in the same way as the particulate, but also the amount of particulate that accumulates on the particulate filter will increase. It becomes difficult to accurately estimate, and there is a problem that forced regeneration of the particulate filter cannot be performed at an appropriate time.

Therefore, when ash has accumulated to some extent on the particulate filter, compressed air is blown from one end of the particulate filter, and the ash accumulated inside is discharged from the other end of the particulate filter. It is necessary to remove the ash deposited on the particulate filter.
By the way, the particulate filter is, as shown in Patent Document 1, a pre-stage oxidation catalyst required for continuous regeneration of the particulate filter and exhaust gas temperature increase, a NOx reduction catalyst for reducing NOx in the exhaust gas, In general, it is used in combination with a downstream oxidation catalyst or the like provided downstream thereof. When such an exhaust purification device is mounted on, for example, a vehicle, for the convenience of layout, an upstream casing in which a front-stage oxidation catalyst and a particulate filter are accommodated, and a NOx catalyst and a rear-stage oxidation catalyst are accommodated. In some cases, the exhaust emission control device is configured such that an outlet that is divided into a downstream casing and that opens to the side on the downstream side of the particulate filter of the upstream casing is connected to the downstream casing.

  In such an exhaust purification device, in order to easily perform the ash removal operation as described above, the upstream casing in which the particulate filter is accommodated is connected to the vicinity of the upstream end of the particulate filter and the vicinity of the downstream end of the particulate filter. And it is set as the structure divided | segmented in the part between the positions which become upstream from an exhaust outlet, and the divided | segmented casing is removed from an upstream casing in the state in which the particulate filter was accommodated. The ash removal operation is performed by supplying compressed air from one opening of the casing thus divided and removed.

The particulate filter after the ash removal is completed is obtained by joining flanges formed at both ends of the divided casing and corresponding flanges provided on the upstream casing side and fixing them with bolts. Then, it is incorporated into the exhaust purification device again.
By the way, the particulate filter has a problem in that continuous regeneration and forced regeneration are not performed well when the exhaust gas temperature decreases. However, an exhaust pipe that supplies exhaust gas to the exhaust gas purification device in order to suppress a decrease in exhaust gas temperature. Has been proposed by Patent Document 2 and the like to have a double tube structure constituted by an inner tube and an outer tube provided with a gap. Similarly to the exhaust pipe having such a double pipe structure, it is conceivable that the casing in which the particulate filter is accommodated is also constituted by a double metal plate. As described above, if the upstream casing is housed in the upstream casing together with the upstream oxidation catalyst, the upstream oxidation catalyst cannot perform its catalytic function well due to a decrease in the exhaust temperature. By doing so, the inside of the upstream casing is insulated, and the temperature drop of the particulate filter, the pre-stage oxidation catalyst, etc. can be suppressed.
JP 2007-162487 A JP 2000-282858 A

  However, in order to remove the ash accumulated on the particulate filter as described above, the particulate filter is accommodated in a casing divided in the upstream casing, and the divided casing is located near the upstream end of the particulate filter. The flange is provided, and is attached to the upstream casing by a flange provided in the vicinity of the downstream end of the particulate filter and on the upstream side of the exhaust outlet.

In addition, when the casing has a double structure, the space between the outer shell and the inner shell is eliminated by reducing the diameter of the outer shell or expanding the inner shell at the flange, and the outer shell and the inner shell are in close contact with each other. In general, the exhaust gas does not enter between the outer shell and the inner shell.
For this reason, the heat insulation effect due to the double structure of the casing cannot be obtained at the flange and its surroundings, but on the outlet side of the particulate filter, since the flange is located upstream from the exhaust outlet, Most of the exhaust gas that has flowed out comes into contact with the flange, and the temperature in the upstream casing decreases due to heat radiation from the flange. As a result, there is a problem that the regeneration of the particulate filter is not performed well, and a problem that the temperature of the catalyst disposed on the downstream side of the particulate filter is lowered and the exhaust purification efficiency of the exhaust purification device is lowered. Arise.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an exhaust purification device capable of suppressing heat radiation from a casing in which a particulate filter is accommodated. .

  In order to achieve the above object, an exhaust emission control device according to the present invention includes an exhaust gas inflow portion into which exhaust gas from the engine flows, in an exhaust gas purification device including a particulate filter that collects particulates contained in the exhaust gas of the engine. A first casing having a downstream end opening through which the exhaust gas that has flowed out flows, and a cylindrical shape having both ends open to accommodate the particulate filter, and the upstream end opening through the connecting member. A second casing provided with an exhaust outlet portion through which the exhaust gas that has passed through the particulate filter flows out on a side wall portion on the downstream side of the particulate filter. It is detachably attached to the second casing through an attachment member, and closes the downstream end opening of the second casing. Characterized in that a lid member that (claim 1).

  According to the exhaust gas purification apparatus configured as described above, the exhaust gas outflow portion through which the exhaust gas that has passed through the particulate filter flows out is provided upstream of the lid member that closes the downstream end opening of the second casing. Most of the exhaust that has passed through the particulate filter flows out from the exhaust outlet without touching the attachment part of the cover member to the second casing, such as the attachment member, the downstream end of the second casing, and the peripheral part of the cover member. To do.

  Further, when removing the ash deposited on the particulate filter, the connection between the upstream end opening of the second casing and the downstream end opening of the first casing via the connecting member is released to remove the second casing from the second casing. While removing from 1 casing, the both-ends opening part of a 2nd casing is exposed by removing the cover member attached via the attachment member from the downstream end opening part of a 2nd casing.

Preferably, in the exhaust emission control device, the first casing and the second casing may be formed of a double metal plate with a heat insulating material interposed therebetween (claim 2).
More preferably, in the exhaust emission control device, the lid member may be formed of a double metal plate with a heat insulating material interposed therebetween.

  According to the exhaust emission control device of the present invention, the connection between the upstream opening of the second casing and the downstream opening of the first casing is performed via the connecting member, and the lid to the downstream opening of the second casing is provided. The attachment of the member is performed via the attachment member, but such a connection member or attachment member does not exist in the region of the second casing between the outlet side of the particulate filter and the exhaust outflow portion. Does not generate heat by the connecting member or the mounting member.

  In addition, since the exhaust outlet portion from which the exhaust gas that has passed through the particulate filter flows out is provided on the side wall portion of the second casing that is upstream from the downstream opening portion of the second casing, the exhaust outlet portion that has flowed out of the particulate filter Most of them flow out from the exhaust outlet without touching the attachment part of the lid member to the second casing, such as the attachment member, the downstream end of the second casing and the peripheral edge of the lid member.

  Therefore, the amount of heat radiation from the mounting member used for mounting the lid member is such that the casing is connected by the flange as the connecting member between the downstream side of the particulate filter and the portion where the exhaust flows out as described above. Compared to the case, the heat radiation from the connecting member can be kept low. As a result, it is possible to suppress a temperature decrease in the second casing and suppress a decrease in exhaust purification efficiency in the exhaust purification device.

Further, according to the exhaust gas purification apparatus of the second aspect, since the first casing and the second casing are formed by the double metal plate with the heat insulating material sandwiched therebetween, the release from the first casing and the second casing is performed. The amount of heat can be reduced, and the heat radiation from the exhaust emission control device can be suppressed even better.
Further, according to the exhaust purification device of claim 3, since the lid member is also formed by a double metal plate with a heat insulating material sandwiched therebetween, the amount of heat released from the lid member is further reduced, and further improved. In addition, heat radiation from the exhaust purification device can be suppressed.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an overall configuration diagram of a four-cylinder diesel engine (hereinafter referred to as an engine) to which an exhaust emission control device according to an embodiment of the present invention is applied, and the exhaust emission control device according to the present invention based on FIG. The structure of will be described.
The engine 1 includes a high-pressure accumulator chamber (hereinafter referred to as a common rail) 2 common to each cylinder, and high-pressure fuel supplied from a fuel injection pump (not shown) and stored in the common rail 2 is supplied to an injector 4 provided in each cylinder. Then, fuel is injected from each injector 4 into each cylinder.

  The intake passage 6 is equipped with a turbocharger 8. The intake air drawn from an air cleaner (not shown) flows into the compressor 8a of the turbocharger 8 from the intake passage 6, and the intake air supercharged by the compressor 8a is intercooler. 10 and the intake control valve 12 are introduced into the intake manifold 14. An intake air amount sensor 16 for detecting an intake air flow rate to the engine 1 is provided upstream of the compressor 8a in the intake passage 6.

On the other hand, an exhaust port (not shown) through which exhaust is discharged from each cylinder of the engine 1 is connected to an exhaust pipe 20 via an exhaust manifold 18. An EGR passage 24 that communicates the exhaust manifold 18 and the intake manifold 14 via the EGR valve 22 is provided between the exhaust manifold 18 and the intake manifold 14.
The exhaust pipe 20 passes through the turbine 8 b of the turbocharger 8 and is connected to an exhaust aftertreatment device 28 via an exhaust throttle valve 26. The rotating shaft of the turbine 8b is connected to the rotating shaft of the compressor 8a so that the turbine 8b receives the exhaust flowing in the exhaust pipe 20 and drives the compressor 8a.

The exhaust aftertreatment device 28 includes an upstream casing 30 and a downstream casing 34 that is communicated with the downstream side of the upstream casing 30 through a communication passage 32. A pre-stage oxidation catalyst 36 is accommodated in the upstream casing 30, and a particulate filter (hereinafter referred to as a filter) 38 is accommodated on the downstream side of the pre-stage oxidation catalyst 36.
The filter 38 is provided for collecting particulates in the exhaust gas and purifying the exhaust gas of the engine 1. The filter 38 is made of a honeycomb-type ceramic body, and a large number of passages communicating with the upstream side and the downstream side are arranged side by side, and the upstream side opening and the downstream side opening of the passage are alternately closed. Particulates in the exhaust are collected as the exhaust flows inside.

Since the front-stage oxidation catalyst 36 oxidizes NO in the exhaust gas to generate NO ₂ , by arranging the front-stage oxidation catalyst 36 and the filter 38 in this way, the particulates collected and deposited in the filter 38 are Then, it reacts with NO ₂ supplied from the pre-stage oxidation catalyst 36 and oxidizes, so that the filter 38 is continuously regenerated.
On the other hand, in the downstream casing 34, there is an ammonia selective reduction type NOx catalyst (hereinafter referred to as SCR catalyst) 40 that adsorbs ammonia in the exhaust gas and selectively reduces and purifies NOx in the exhaust gas using the adsorbed ammonia as a reducing agent. In addition to being accommodated, a downstream oxidation catalyst 42 for oxidizing ammonia flowing out from the SCR catalyst 40 to N ₂ is accommodated on the downstream side of the SCR catalyst 40. The post-stage oxidation catalyst 42 also has a function of oxidizing CO generated when the particulates are incinerated by forced regeneration of the filter 38 and discharging it to the atmosphere as CO ₂ .

A urea water supply nozzle 44 for injecting and supplying urea water into the exhaust gas flowing out from the filter 38 and flowing into the communication passage 32 is provided on the downstream side of the filter 38 of the upstream casing 30. Urea water is supplied from the water tank to the urea water supply nozzle 44.
The urea water injected from the urea water supply nozzle 44 is hydrolyzed by the heat of the exhaust to become ammonia, and is supplied to the SCR catalyst 40. The SCR catalyst 40 adsorbs the supplied ammonia and promotes a denitration reaction between the adsorbed ammonia and NOx in the exhaust, thereby purifying NOx to be harmless N ₂ . At this time, when ammonia flows out of the SCR catalyst 40 without reacting with NOx, the ammonia is oxidized by the post-stage oxidation catalyst 42 and released into the atmosphere as harmless N _2. Yes.

Next, the configuration on the upstream casing 30 side in the exhaust aftertreatment device 28 will be described in more detail with reference to FIG.
FIG. 2 is a cross-sectional view of the main part of the exhaust aftertreatment device 28 on the upstream casing 30 side, and the upstream casing 30 is divided into a first casing 46 and a second casing 48 as shown in FIG. Yes. The first casing 46 accommodates the front-stage oxidation catalyst 36 and is connected to the exhaust pipe 20 so that the exhaust inflow portion 50 into which the exhaust of the engine 1 flows in and the downstream end opening portion through which the exhaust that has passed through the front-stage oxidation catalyst 36 flows out. 52. The second casing 48 has a cylindrical shape with both ends opened to accommodate the filter 38, the upstream end opening 54 is connected to the downstream end opening 52 of the first casing 46, and the filter 38 in the side wall 56. An exhaust outflow portion 58 through which the exhaust gas that has passed through the filter 38 flows out toward the communication path 32 is provided at a portion on the further downstream side. The first casing 46 and the second casing 48 are provided in a first flange (connection member) 60 provided in the downstream end opening 52 of the first casing 46 and in an upstream end opening 54 of the second casing 48. The second flange (connecting member) 62 is joined, and the bolt 64 and the nut 66 are fastened so as to be detachable.

  The exhaust outlet 58 of the second casing 48 is formed in a cylindrical shape so as to cross the second casing 48, and the exhaust gas that has passed through the filter 38 is formed on the peripheral wall of the exhaust outlet 58. And then flows into the downstream casing 34 through the communication passage 32 connected to one end of the exhaust outlet 58. The other end portion of the exhaust outflow portion 58 reaches the side wall portion 56 of the second casing 48, and is substantially at the center of the region of the side wall portion 56 surrounded by the other end portion of the exhaust outflow portion 58. Is provided with a urea water supply nozzle 44 for injecting urea toward the axial direction of the exhaust outlet portion 58. The urea water supply nozzle 44 supplies ammonia generated from urea water to the SCR catalyst 40 in the downstream casing 34 as described above by injecting urea water into the exhaust gas flowing into the exhaust gas outlet 58. To do.

  A downstream end opening 68 of the second casing 48 on the downstream side of the exhaust outflow portion 58 is closed by a lid member 70. The lid member 70 joins a third flange (attachment member) 72 provided at the downstream end opening 68 of the second casing 48 and a fourth flange (attachment member) 74 provided at the peripheral edge of the lid member 70. In addition, the bolt 76 and the nut 78 are fastened so that the downstream end opening 68 is detachably attached.

  The first casing 46 is formed by a composite metal plate that is doubled with a heat insulating material interposed therebetween except for the attachment portion of the first flange 52 and the exhaust inflow portion 50. Further, the second casing 48 is also formed of the same composite metal plate except for the mounting portions of the second flange 62 and the third flange 72 and the exhaust outflow portion 58, and the lid member 70 also has the fourth flange. Except for the attachment part 74, it is formed of the same composite metal plate. In addition, in each attachment part of the 1st flange 52, the 2nd flange 62, and the 3rd flange 72, in order to prevent exhaust_gas | exhaustion from entering between the metal plates piled up double, an outer metal plate is reduced in diameter. It is made to join directly with the inner metal plate.

  In this way, by forming the first casing 46, the second casing 48, and the lid member 70 with the composite metal plate, the heat radiation from the first casing 46, the second casing 48, and the lid member 70 is reduced, and the inside While suppressing the temperature drop of the stored pre-stage oxidation catalyst 36 and the filter 38, the temperature drop of the exhaust gas flowing into the downstream casing 34 from the upstream casing 30 is also suppressed, and the exhaust purification efficiency of the exhaust aftertreatment device 28 is reduced. I try to prevent it.

  Further, there is no flange serving as a heat radiator between the outlet side of the filter 38 and the exhaust outflow portion 58, and a third flange for attaching the lid member 70 to the downstream end opening 68 of the second casing 48. 72 and the fourth flange 74 are located downstream of the exhaust outlet 58. For this reason, most of the exhaust gas flowing out from the filter 38 and flowing into the exhaust gas outlet 58 has the second casing 48 in which the two metal plates of the composite metal plate are directly joined and the heat insulation effect by the composite metal plate cannot be obtained. The gas flows into the exhaust gas outlet 58 without coming into contact with the portion near the downstream end opening 68 or the third flange 72 and the fourth flange 74 and flows out into the communication passage 32.

  Accordingly, it is possible to suppress a temperature decrease in the second casing 48 due to heat radiation from the third flange 72 and the fourth flange 74 and to suppress a temperature decrease of the exhaust gas flowing from the upstream casing 30 to the downstream casing 34. . As a result, the filter 38 can be regenerated satisfactorily, and the exhaust purification efficiency of the SCR catalyst 40 and the downstream oxidation catalyst 42 accommodated in the downstream casing 34 can be maintained well.

  Next, the removal of ash deposited on the filter 38 will be described below. When removing the ash of the filter 38, the bolt 64 and the nut 66 that connect the first casing 46 and the second casing 48 are removed, and the exhaust outlet 58 and the communication passage 32 of the second casing 48 are connected. The connected bolt 80 and nut 82 are removed, and the second casing 48 is taken out from the exhaust aftertreatment device 28 while the filter 38 is accommodated. Further, the bolt 76 and the nut 78 fixing the lid member 70 to the downstream end opening 68 of the second casing 48 are removed, and the lid member 70 is removed from the downstream end opening 68 of the second casing 48.

By doing so, as shown in FIG. 3, the second casing 48 is in a state where both the upstream end and the downstream end are open. In this state, ash accumulated in the filter 38 is discharged from the upstream end opening 54 of the second casing 48 by supplying compressed air in the direction of the arrow A shown in FIG.
After removing the ash from the filter 38 in this way, the lid member 70 is attached to the second casing 48 by the bolts 76 and 78 again to close the downstream end opening 68. Then, the first flange 60 and the second flange 62 are joined and the bolt 64 and the nut 66 are fastened to connect the second casing 48 to the first casing 46, and the bolt 80 and the nut 82 are fastened to the second. By connecting the exhaust outlet portion 58 of the casing 48 to the communication path 32, the assembly of the second casing 48 to the exhaust aftertreatment device 28 is completed.

As described above, after the second casing 48 is removed from the exhaust post-treatment device 28, the lid member 70 is removed from the second casing 48, so that openings are formed at both ends of the second casing 48. Ashes can be easily removed.
Although the description of the exhaust emission control device according to one embodiment of the present invention is finished above, the present invention is not limited to the above embodiment.

  For example, in the above embodiment, the exhaust aftertreatment device 28 is configured by the front stage oxidation catalyst 36 and the filter 38 housed in the upstream casing 30 and the SCR catalyst 40 and the rear stage oxidation catalyst 42 housed in the downstream casing 34. However, the configuration of the exhaust aftertreatment device 28 is not limited to this. That is, the pre-stage oxidation catalyst 36, the SCR catalyst 40, and the post-stage oxidation catalyst 42 may be appropriately provided as necessary. For example, a catalyst other than the SCR catalyst 40 and the post-stage oxidation catalyst 42 is provided in the downstream casing 34. You may do it.

In the above embodiment, as shown in FIG. 3, the compressed air is supplied from the downstream end opening 68 of the second casing 48 to remove the ash, but the ash removal method is limited to this. is not. For example, compressed air may be supplied from the upstream end opening 54 of the second casing 48, or a fluid other than the compressed air may be used.
Furthermore, in the above-described embodiment, the engine 1 is a four-cylinder diesel engine. However, as long as the engine requires the filter 38, the type and the number of cylinders are not limited thereto.

1 is an overall configuration diagram of an engine to which an exhaust emission control device according to an embodiment of the present invention is applied. It is principal part sectional drawing of the exhaust gas aftertreatment apparatus in the exhaust gas purification apparatus of FIG. It is principal part sectional drawing of the 2nd casing removed from the exhaust gas aftertreatment apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 20 Exhaust pipe 28 Exhaust after-treatment apparatus 30 Upstream casing 34 Downstream casing 36 Pre-stage oxidation catalyst 38 Particulate filter 46 First casing 48 Second casing 50 Exhaust inflow part 52 Downstream end opening 54 Upstream end opening 56 Side wall 58 exhaust outlet 60 first flange (connecting member)
62 Second flange (connecting member)
68 Downstream end opening 70 Lid member 72 Third flange (mounting member)
74 4th flange (mounting member)

Claims (3)

In an exhaust emission control device having a particulate filter that collects particulates contained in engine exhaust,
A first casing having an exhaust inflow portion through which exhaust of the engine flows, and a downstream end opening through which the exhaust that has flowed out flows;
Both ends of the particulate filter are accommodated in an open cylindrical shape, and the upstream end opening is detachably connected to the downstream end opening of the first casing via a connecting member. A second casing provided with an exhaust outlet portion through which the exhaust gas that has passed through the particulate filter flows out on a downstream side wall portion;
An exhaust purification device comprising: a lid member that is detachably attached to the second casing via an attachment member, and that closes a downstream end opening of the second casing.   2. The exhaust emission control device according to claim 1, wherein the first casing and the second casing are formed of a double metal plate with a heat insulating material interposed therebetween.   The exhaust purification device according to claim 2, wherein the lid member is formed of a double metal plate with a heat insulating material interposed therebetween.

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