JP2590160Y2 - Exhaust gas purification device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifier for removing particulates contained in gas discharged from an internal combustion engine such as a diesel engine, and more particularly to an exhaust gas purifier having improved durability. About.

[0002]

2. Description of the Related Art Conventionally, as an exhaust gas purifying apparatus of this type, a catalyst carrier having a honeycomb structure integrally formed of a porous ceramic sintered body in a casing having a passage communicating with the exhaust side of an internal combustion engine, It is generally known that a filter composed of a catalyst component supported on the catalyst carrier is arranged, and a heat source such as a burner is arranged between the internal combustion engine and the filter. After a predetermined amount of particulates are collected in the filter, the particulates are heated by a heat source such as a burner to burn the collected particulates, perform a regeneration process, and are used as a filter again.

However, a filter is used as a heat source such as a burner.
Therefore, when heated, for example , the temperature at the center of the end face on the exhaust gas inflow side corresponding to the position of the flame of the burner tends to rise in a shorter time than at other parts. In particular, in the case of the catalyst carrier integrally formed of the same material, a temperature difference easily occurs between the center portion and the outer peripheral portion of the catalyst carrier and between both end surfaces of the catalyst carrier, and the catalyst carrier increases accordingly. There is a possibility that the catalyst support may be broken by the circumferential stress and the radial stress (tensile stress or compressive stress). Therefore, the durability of the entire filter is inferior, and there has been a problem that the regeneration process cannot be repeated many times.

Further, in the method of heating the filter to a temperature higher than the burning temperature of the particulates by a heat source such as a burner to burn and remove the particulates, the particulates are uniformly collected by the filter and unless the particulates are uniformly burned, the particulates are not removed. Since the amount of heat generated by combustion of the curate differs in each part of the filter, a temperature difference occurs in each part of the filter. As a result, thermal expansion of the filter, the difference in amount of shrinkage Ji live, so that the stress of such tension compression filter at each site occurs. If this is repeated, the deterioration of the filter progresses, leading to destruction.

[0005] Further, if there is a difference in the amount of trapped particulates in each part of the filter or if the total amount of trapped particulates is too large, the temperature of the re-filter, which generates a large amount of particulate combustion heat, exceeds the heat resistance temperature. The filter may be melted or damaged. If the filter is frequently regenerated to solve the above-mentioned disadvantages, the regenerative energy is significantly increased, and the filter cannot be put to practical use. Therefore, it is necessary to improve the regeneration efficiency by reducing the number of times of regeneration as much as possible. However, as the amount of trapped particulates increases, clogging of the filter progresses and the flow of exhaust gas deteriorates. As a result, the efficiency of the engine deteriorates.

[0006] Furthermore, as the size of the filter increases, the amount of particulates collected at each portion of the filter is uniform, and the temperature near the center of the filter is highest even when the amount of heat generated by combustion is constant per unit volume. There is a tendency. A method for solving such a problem includes A.I. B. Method of hollowing out the center of the filter. A method of increasing the thickness of the filter cell wall stepwise toward the center has been proposed. In the method A, material loss occurs by hollowing the integrally formed filter center. In addition, special consideration is required for the mall structure in the center. B
The method has the drawbacks that it is difficult to produce dies and that the material is difficult to be fed during extrusion molding, resulting in poor molding yield, as well as an increase in the occurrence of defects in the drying to baking steps, and that practical use is difficult. Was.

[0007]

[Problems to be Solved by the Invention] The present inventors have completed the present invention as a result of various studies to improve such disadvantages. The purpose of the present invention is to reduce the particulates collected by the filter. An object of the present invention is to provide a highly durable exhaust gas purifying apparatus that does not cause concentration of stress on a specific portion of a catalyst carrier by burning and removing.

[0008]

The gist of the present invention is that a honeycomb formed of a honeycomb-shaped porous sintered body with a number of gas passage holes parallel to an axial direction is provided in a casing provided in an exhaust pipe of an internal combustion engine. In an exhaust gas purifying apparatus provided with a filter, the honeycomb filter includes a plurality of honeycomb filters arranged in parallel.
Is constituted by <br/> divided portion having a plurality of gas passage holes parallel to split axially, the divided portion constituting the vicinity of the center portion of the honeycomb filter, the exhaust gas upstream of the internal combustion engine side It is divided into the downstream part on the discharge side and the upstream part
The gas passage hole of the divided portion is not sealed at both end surfaces, the gas passage hole of the downstream divided portion is sealed at one of the end surfaces, and the divided portion constituting the vicinity of the peripheral portion of the honeycomb filter. The exhaust gas purifying device is characterized in that the portion has one end face of the gas passage hole sealed.

[0009] That is, by the filter disposed in the casing communicating with the exhaust side of the internal combustion engine is composed of divided wedges into multiple pieces in the present invention, the stress generated by thermal expansion and contraction caused by the reproduction process And reduce
In order to mitigate the temperature rise near the center due to the heat generated by the burning of particulates, of the plurality of divided parts, the plurality of divided parts forming the vicinity of the center are placed on the upstream side.
The gas is divided into a divided part and a downstream divided part . The upstream divided part is an unsealed body in which both end faces of the gas passage hole are not sealed, and the downstream divided part is sealed with one end face of the gas passage hole. A perforated sealing body prevents abnormal temperature rise near the center of the burner side, and separates the downstream side.
By promoting the heat flow to the part , the temperature rise of the entire filter is uniform and quick, and the particulate density near the center becomes smaller than the density near the outer part, The filter can be prevented from being damaged due to abnormal temperature rise near the center due to burning and heat generation of particulates.

[0010] A plurality of divided portions constituting the outer peripheral portion of the filter have a larger trapping density per unit volume than those near the center portion (the cell wall thickness is smaller and the cell pitch is smaller). It is preferable to select a small filter. Also, among the divided parts, a plurality of divided parts near the center are divided in the axial direction on the upstream side and the downstream side, and the upstream side is an unsealed body and the downstream side is a sealed body. In this case, the ratio (A) / (B) of the length (A) of the unsealed body to the length (B) of the sealed body can be increased as the filter capacity increases and the trapping density increases. desirable.

The present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of an exhaust gas purification device. FIG. 2 is a front view of a honeycomb filter used in the exhaust gas purifying apparatus of the present invention, and FIG. 3 is a sectional view thereof. In FIG. 1, the exhaust gas purifying apparatus 1 includes a metal casing 2, and a passage 2 a of the casing 2 is connected to an exhaust pipe Ea of the internal combustion engine E. Honeycomb filter 3 for purifying exhaust gas is disposed in the casing 2. A space between the honeycomb filter 3 and the inner wall of the passage 2a of the casing 2 is filled with a heat insulating support member made of a ceramic fiber or a ceramic fiber composite.

The honeycomb filter 3 is parallel to the axial direction.
Formed in a honeycomb shape by a large number of gas passage holes extending
Formed by the porous silicon carbide sintered body .
One end of the supply side 4 and one end of the discharge side 5 of each gas passage hole are alternately sealed. Further, an oxidation catalyst comprising a platinum group element, other metal elements, and an oxidized substance thereof is carried on the inner wall surface of each gas passage hole of the honeycomb filter 3. Therefore,
When the exhaust gas from the internal combustion engine E is introduced into the honeycomb filter from the supply side of the casing 2, the particulates in the exhaust gas are filtered by the walls of the gas passage holes and oxidized by the oxidation catalyst. Then, the purified exhaust gas is exhausted from the exhaust side 5 of the honeycomb filter 3.

When performing the regeneration processing of the honeycomb filter 3 used as described above, the honeycomb filter 3
In a state of being collected a predetermined amount of particulates, the heating is started in the honeycomb filter 3 by the heat source such as a burner 7. Then, the particulate matter collected in the honeycomb filter 3 is burned and regenerated.

Next, the structure of the honeycomb filter 3 used in the present invention will be described in detail. As shown in FIG. 2, the honeycomb filter 3 used in the present invention is configured by connecting a plurality of quadrangular prism-shaped divided portions 8 and 9 to each other by a sealant 10. Wedges 8 is a divided portion which constitutes the peripheral portion of the honeycomb filter 3, distribution such that the end surface of the supply side of the gas passage holes are sealed in a checkered pattern
And the discharge side of the gas passage hole whose supply side is not sealed is arranged so as to be sealed. And the division part 9 near the center part of the honeycomb filter 3 is comprised of nine division parts. The divided portion 9 that forms the vicinity of the center is divided into a gas supply side (upstream side) 9a and a discharge side (downstream side) 9b. As shown in FIG.
The side divided portion 9a is an unsealed body whose both end faces are not sealed.
Yes, the downstream split part 9b is the same as the peripheral split part.
A sealing body with one of the sides sealed.
You . In addition, the length (A) of the divided portion composed of the unsealed body on the upstream side of the middle portion constituting the central portion of the honeycomb filter
And the length (B) of the divided portion consisting of the downstream-side sealing body is (A) / (B) = 4/1, and the other eight lengths disposed around the periphery are (A) / (B) = 4/1. The ratio of (A) /
(B) = 2/1.

By adopting the above filter structure, the particulate collection density near the center becomes smaller than that at the outer periphery, and the amount of accumulated particulates near the center on the burner side becomes very small. This eliminates an abnormal temperature rise in the filter due to regeneration, thereby preventing filter deterioration during regeneration processing.

[0016]

As described above, according to the present invention, in the exhaust gas purifying apparatus, the honeycomb filter to be used is composed of a plurality of divided portions, and the divided portions near the center are divided into the upstream side and the downstream side. By making the upstream side unsealed, the filter is not heated at all, unlike the conventional one, so that the filter is not deteriorated and the collected particulates are heated. In order to do so, it became possible to do it with very little energy.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an exhaust gas purifying apparatus according to the present invention.

FIG. 2 is a front view of a filter used in the exhaust gas purifying apparatus according to the present invention.

FIG. 3 is a side sectional view of a filter used in the exhaust gas purifying apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust gas purification apparatus 2 Casing 3 Honeycomb filter 4 Exhaust gas introduction side 5 Exhaust gas discharge side 6 Exhaust pipe 7 Burner 8 Filter division part 9 Division part near center part 10 Seal material 9a Upstream division part 9b Downstream division part

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01N 3/02 301 F01N 3/02 321

Claims (1)

(57) [Scope of request for utility model registration] 1. An exhaust gas purifying apparatus comprising a casing provided in an exhaust pipe of an internal combustion engine and a honeycomb filter formed of a porous sintered body having a honeycomb shape formed by a large number of gas passage holes parallel to an axial direction. The honeycomb filter is composed of a plurality of parallel divided axially parallel filters.
It is constituted by a divided portion having a gas passage hole ,
The divided parts that constitute the vicinity of the center portion of the honeycomb filter, Yes divided into the downstream portion of the upstream portion of the internal combustion engine side exhaust gas discharge side, the gas passage holes in the upstream portion wedges the end surfaces thereof are sealed No, the gas passage hole of the downstream divided portion has one end face sealed, and the divided portion constituting the vicinity of the peripheral portion of the honeycomb filter has one end face of the gas passage hole. An exhaust gas purification device characterized by being sealed.