JP2003214136A - Exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent blocking at an entering side end face of a particulate filter without deterioration in mounting ability to a vehicle and without increasing cost. <P>SOLUTION: In the exhaust emission control device in which the particulate filter 4 is mounted in the middle of an exhaust pipe 3, an oxidation catalyst layer 15 is carried on a surface which is in contact with an exhaust gas 2 in sheet metal parts (a filter case 7, an inlet pipe 8, the exhaust pipe 3, a pipe support 16, a dispersion plate 10) forming a flowing space of the exhaust gas 2 at a more upstream side than the particulate filter 4. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust emission control device.

[0002]

2. Description of the Related Art Particulate Matter (Particulate Matter) emitted from a diesel engine is
Soot composed of carbonaceous matter and SO composed of high boiling hydrocarbon components
It is composed of F component (Soluble Organic Fraction) as a main component and further contains a trace amount of sulfate (mist-like sulfuric acid component). As a countermeasure for reducing this type of particulates, FIG. As shown in, the exhaust pipe 3 through which the exhaust gas 2 from the diesel engine 1 flows
It is considered to equip the particulate filter 4 in the middle of.

As shown in FIG. 3, the particulate filter 4 has a porous honeycomb structure made of a ceramic such as cordierite, and the inlets of the channels 4a divided into a lattice are plugged by plugs 4b. Regarding the flow paths 4a which are alternately plugged and whose inlets are not plugged, their outlets are plugged by the plugs 4b and permeate through the porous thin wall 4c which partitions each flow path 4a. Exhaust gas 2
Only the particles are discharged to the downstream side, and the particulates are collected on the inner surface of the porous thin wall 4c.

In this type of particulate filter 4, since the flow of the exhaust gas 2 stagnates at the front surface of the plug 4b on the inlet side, particulates are easily attached and deposited here, and the particulate is deposited. There is a risk that the particulates may gradually grow and block the inlet side end surface (the unsealed flow path 4a) of the particulate filter 4.

As a countermeasure against such a problem,
A flow-through type oxidation catalyst 5 having a honeycomb structure as shown in an enlarged scale in FIG. 4 is arranged in the front stage of the particulate filter 4, and the oxidation catalyst 5 is used to remove the SOF component of the mucus in advance so that the particulates in the rear stage are removed. It has been studied to prevent the adhesion and deposition of particulates on the front surface of the plug body 4b on the inlet side of the particulate filter 4 by making the property of the particulates guided to the filter 4 into a dry state to significantly reduce the adhesiveness. There is.

That is, in comparison with soot, which requires a certain holding time for oxidative purification, the SOF component is easily combustible and can be oxidatively purified by securing a short catalyst contact time. The SOF component can be relatively easily burned and removed only by passing the gas 2 through the flow-through type oxidation catalyst 5.

Since the particulate filter 4 in the latter stage collects the particulates mainly composed of soot, which is in a dry state due to the mucus-like SOF component being removed in advance, the SOF component is collected on the surface. The combustibility is improved as compared with the case of particulates mainly composed of tinged wet state soot, and the problem that hard deposits due to carbonization is less likely to occur because the SOF component does not burn together.

[0008]

However, as described above, when the oxidation catalyst 5 is arranged in front of the particulate filter 4, a space for disposing the oxidation catalyst 5 must be newly secured, and the oxidation catalyst 5 is mounted on the vehicle. There is a problem that the property is deteriorated and the cost required for the new placement of the oxidation catalyst 5 is soaring.

The present invention has been made in view of the above-mentioned circumstances, and makes it possible to surely avoid blockage of the entrance side end surface of the particulate filter without deteriorating the mountability on the vehicle and increasing the cost. Is intended.

[0010]

DISCLOSURE OF THE INVENTION The present invention is an exhaust gas purification device equipped with a particulate filter in the middle of an exhaust pipe, and a sheet metal part forming an exhaust gas distribution space upstream of the particulate filter. The oxidation catalyst layer is supported on the surface of the exhaust gas in contact with the exhaust gas.

Thus, in this way, even if the flow-through type oxidation catalyst is not arranged in the preceding stage of the particulate filter, while the exhaust gas flows through the circulation space on the upstream side of the particulate filter, the oxidation catalyst is formed. Since the mucous SOF component is removed in advance by contact with the layer, the property of the particulates introduced to the particulate filter becomes a dry state, and the stickiness is greatly reduced, which results in a plug on the inlet side of the particulate filter. It prevents the particulates from adhering to and depositing on the front surface of the body.

Moreover, since it is not necessary to secure a new space for disposing the oxidation catalyst, deterioration of the mountability on the vehicle is avoided, and the oxidation catalyst layer is directly supported on the sheet metal parts. The cost is reduced because the carrier is unnecessary.

Further, in practicing the present invention, a filter case holding a particulate filter, an inlet pipe fitted into an inlet portion of the filter case, and an upstream side of the inlet pipe are connected. An exhaust catalyst, a pipe support for supporting the inlet pipe in the filter case, and an oxidation catalyst layer for at least one of sheet metal parts of the dispersion plate installed on the inlet side of the particulate filter in the filter case. Should be supported.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an embodiment of the present invention. In the example shown here, exhaust gas 2 discharged from a diesel engine 1 of an automobile (see FIG. 2) is circulating. The case where the particulate filter 4 is housed in the muffler 6 of the exhaust pipe 3 is illustrated, and the filter case 7 that holds the particulate filter 4 forms the outer cylinder of the muffler 6.

That is, between the inlet pipe 8 and the outlet pipe 9 (tail pipe) of the muffler 6, a storage space of a required size defined by the dispersion plates 10 and 11 having a large number of communication holes is secured. The particulate filter 4 is housed in this housing space.

As in the case of FIG. 3 described above, the particulate filter 4 has a porous honeycomb structure made of a ceramic such as cordierite, and the inlets of the channels 4a partitioned in a grid pattern are plugged. For the flow path 4a that is alternately plugged by the body 4b and the inlet is not plugged,
The outlet side is plugged by a plug 4b, and only the exhaust gas 2 that has permeated through the porous thin wall 4c that defines each flow path 4a is discharged to the downstream side.

Further, this particulate filter 4
The end plates 1 at the outer edges of the entrance end surface and the exit end surface.
It is hooked by 2 so as to be restrained from moving in the axial direction, and its outer peripheral surface portion is held by a net material 13 (cushion material) formed by weaving a metal wire material such as stainless steel. A seal member 14 is provided at an intermediate position in the axial direction of the net member 13 so as to prevent the exhaust gas 2 from bypassing.

In the present embodiment, the oxidation catalyst layer 15 is carried on the surface of the sheet metal part forming the flow space of the exhaust gas 2 upstream of the particulate filter 4 in contact with the exhaust gas 2. More specifically, more specifically, a range of the inner surface of the filter case 7 on the upstream side of the particulate filter 4, an inner surface of the inlet pipe 8, and an exhaust pipe 3 connected on the upstream side of the inlet pipe 8. The oxidation catalyst layer 15 is directly supported on the side surface, the inner surface of the pipe support 16 that supports the inlet pipe 8 in the filter case 7, and the front surface of the dispersion plate 10 installed on the inlet side of the particulate filter 4. ing.

Thus, in this way, even if the flow-through type oxidation catalyst as shown in FIG. 4 is not arranged in the preceding stage of the particulate filter 4, the particulate filter 4 is upstream of the particulate filter 4. While the exhaust gas 2 flows through the circulation space, the SOF component of mucus is removed by contact with the oxidation catalyst layer 15, so that the properties of the particulates guided to the particulate filter 4 become a dry state and the adhesiveness is significantly increased. As a result, the particulate matter is prevented from adhering to and depositing on the front surface of the plug body 4b on the entrance side of the particulate filter 4.

Moreover, since it is not necessary to secure a new space for disposing the oxidation catalyst, deterioration of the mountability on the vehicle is avoided, and the oxidation catalyst layer 15 is directly supported on the sheet metal parts, so that the catalyst carrier is supported. Therefore, the cost is reduced because it is unnecessary.

Therefore, according to the above-described embodiment, it is possible to reliably prevent the entrance side end surface of the particulate filter 4 from being blocked without causing deterioration in mountability on a vehicle and cost increase.

The exhaust gas purifying apparatus of the present invention is not limited to the above-described embodiment, but the illustrated example is merely an example of sheet metal parts, and the filter case is a muffler. Needless to say, they may be provided separately, and various changes may be made without departing from the scope of the present invention.

[0024]

According to the above-described exhaust gas purifying apparatus of the present invention, the oxidation catalyst carried on the sheet metal part upstream of the particulate filter is disposed without disposing the flow-through type oxidation catalyst in the preceding stage of the particulate filter. SOF by layer
It is possible to prevent the particulate matter from adhering to and depositing on the front surface of the plug on the entrance side of the particulate filter. It is possible to obtain an excellent effect that it is possible to reliably avoid the closing of the inlet end surface of the curate filter.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing an example of an embodiment for carrying out the present invention.

FIG. 2 is a conceptual diagram of a conventional device equipped with a particulate filter in the middle of an exhaust pipe.

3 is a sectional view showing a detailed structure of the particulate filter of FIG.

FIG. 4 is a partially cutaway perspective view showing a schematic structure of a flow-through type oxidation catalyst.

[Explanation of symbols]

2 exhaust gas 3 Exhaust pipe (sheet metal parts) 4 Particulate filter 7 Filter case (sheet metal parts) 8 Inlet pipe (sheet metal parts) 10 Dispersion plate (sheet metal parts) 15 Oxidation catalyst layer 16 Pipe support (sheet metal parts)

Claims (2)

[Claims] 1. An exhaust gas purification device equipped with a particulate filter in the middle of an exhaust pipe, wherein the surface of the sheet metal part forming an exhaust gas flow space upstream of the particulate filter is in contact with the exhaust gas. An exhaust emission control device having a catalyst layer supported thereon. 2. A filter case holding a particulate filter, an inlet pipe fitted into an inlet portion of the filter case, an exhaust pipe connected to an upstream side of the inlet pipe, and the inlet pipe being the filter. The oxidation catalyst layer is carried on at least one of sheet support parts of a pipe support supported in the case and a dispersion plate installed on the entrance side of the particulate filter in the filter case. The exhaust emission control device according to 1.