JPH0643212U - Exhaust gas purification device - Google Patents

Abstract

(57) [Abstract] [Purpose] An exhaust gas purification device for removing particulates contained in gas discharged from an internal combustion engine such as a diesel engine, in particular, exhaust gas purification with improved durability Regarding the device. Regarding [Composition] In a casing provided in an exhaust pipe of an internal combustion engine,
An exhaust gas purifying apparatus having a honeycomb filter made of a porous sintered body having a honeycomb shape with a large number of gas passage holes parallel to the axial direction, wherein the honeycomb filter of the porous sintered body is on the internal combustion engine side. Is divided into an upstream part and a downstream part on the exhaust gas discharge side, and both end faces of the gas passage hole in the upstream part are not sealed, and the gas passage hole in the downstream part is either end face thereof. Is an exhaust gas purifying device.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an exhaust gas purifying apparatus for removing particulates contained in gas discharged from an internal combustion engine such as a diesel engine, and more particularly to an exhaust gas purifying apparatus having improved durability.

[0002]

[Prior art]

 Conventionally, this type of exhaust gas purifying apparatus has a honeycomb-shaped catalyst carrier integrally formed by a porous ceramic sintered body in a casing having a passage communicating with the exhaust side of an internal combustion engine, and its catalyst. It is generally known that a filter composed of a catalyst component carried on a carrier is arranged, and a heat source such as a burner is arranged between the internal combustion engine and the filter. Then, after collecting a predetermined amount of particulates in the filter, the particulates are heated by a burner to burn the collected particulates for regeneration treatment, and the particulates are used again as a filter.

However, when the filter is heated as described above, the temperature of the central portion of the end surface of the exhaust gas inflow side, which corresponds to the position of the flame of the burner, rises in a shorter time than other parts. Tend to In particular, in the case of the catalyst carrier integrally formed of the same material, a temperature difference is likely to occur between the center part and the outer peripheral part of the catalyst carrier and between both end faces of the catalyst carrier, and the catalyst increases accordingly. There is a risk that the catalyst carrier may be destroyed by stress (tensile stress or compressive stress) in the circumferential and radial directions of the carrier. Therefore, there was a problem that the durability of the entire filter was poor and the regeneration process could not be repeated many times.

Furthermore, in the method of burning and removing the particulates by heating the filter to the burning temperature of the particulates or higher by a burner and / or a heater, the particulates are evenly distributed on the filter. Unless the particles are collected and burned uniformly, the calorific value of combustion of the particulates is different in each part of the filter, so that a temperature difference occurs in each part of the filter. As a result, if a difference in the amount of thermal expansion and contraction of the filter is produced, stress such as compression and tension is generated in each part of the filter. By repeating this process, the deterioration of the filter progresses and the filter is destroyed.

Further, if there is a difference in the amount of collected particulates in each part of the filter, or if the total amount of collected particulates is too large, the amount of heat generated by burning particulates becomes large and the heat-resistant temperature of the filter rises. The filter may be melted or damaged. If the filter is frequently regenerated in order to solve the above-mentioned drawbacks, the regenerative energy will increase remarkably, and the filter cannot be put to practical use. Therefore, it is necessary to reduce the number of regenerations as much as possible to improve the regeneration efficiency, but as the amount of particulates collected increases, the filter clogging progresses and the exhaust gas flow deteriorates. . As a result, the efficiency of the engine deteriorates.

Further, as the filter becomes larger, the amount of particulate trapped in each part of the filter becomes uniform, and if the combustion heat generation amount is constant per unit volume, the temperature near the center of the filter becomes the most. There is a tendency for it to be higher. As a method for solving such a problem, A. A method of hollowing the center of the filter, B. Although a method has been proposed in which the filter cell wall thickness is gradually increased toward the center, etc., in method A, material loss is caused by hollowing the integrally formed filter center. Not only that, special consideration is needed for the center structure. Method B has the drawbacks that it is difficult to manufacture dies and that it is difficult to feed the materials during extrusion molding and the molding yield deteriorates, and it also causes the occurrence of defects in the drying and firing processes, making it difficult to put into practical use. Was.

[0007]

[Problems to be solved by the device]

 The present inventor has completed the present invention as a result of various studies to improve such a drawback, and the purpose of the present invention is to remove the particulate matter trapped in the filter by burning to remove the catalyst carrier. An object of the present invention is to provide an exhaust gas purifying device having high durability without causing stress concentration on a specific part of the exhaust gas.

[0008]

[Means for Solving the Problems]

 The gist of the present invention is an exhaust gas in which a honeycomb filter made of a honeycomb-shaped porous sintered body is arranged in a casing provided in an exhaust pipe of an internal combustion engine by a large number of gas passage holes extending in the axial direction. In the gas purification apparatus, the honeycomb filter is composed of a plurality of divided parts, and the divided part that constitutes the vicinity of the central part of the honeycomb filter is an upstream part on the internal combustion engine side and a downstream part on the exhaust gas discharge side. The gas passage hole in the upstream part is not sealed at both end faces, and the gas passage hole in the downstream part is sealed at either one of the end faces, and the periphery of the honeycomb filter is closed. The exhaust gas purifying device is characterized in that one of the end faces of the gas passage hole is sealed in the divided portion that constitutes the vicinity of the portion.

That is, in the present invention, the filter disposed in the casing communicating with the exhaust side of the internal combustion engine is composed of a plurality of divided parts, so that the thermal expansion / contraction associated with the regeneration process is performed. In order to reduce the stress generation due to and to alleviate the temperature rise near the central part due to the combustion heat generation of the particulates, among the divided parts divided into multiple parts, the multiple divided parts of the central part are By further dividing the upstream side and the downstream side in the axial direction, the upstream side divided part is a non-sealing body and the downstream side divided part is a sealing body in which either one of the gas passage holes is sealed. , The abnormal temperature rise near the center of the burner side is prevented, the heat flow to the downstream side is promoted, and the temperature rise of the entire filter is uniformed and speeded up. -The collection density is outside By lowering the collection density near the periphery, it is possible to prevent filter damage due to abnormal temperature rise near the center due to particulate combustion and heat generation.

In addition, the divided part that is divided into a plurality of parts constituting the outer peripheral part of the filter has a higher trapping density per unit volume than that of the part near the center part (thin cell wall thickness, cell pitch It is preferable to select a filter having a small In addition, among the divided parts divided into a plurality of parts, a plurality of divided parts near the center part are divided in the axial direction of the upstream side and the downstream side, the upstream side is a non-sealing body and the downstream side is a sealing body. In this case, the ratio (A) / (B) of the length of the unsealed body (A) and the length of the sealed body (B) should be increased as the filter capacity and the collection density increase. Is desirable.

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

The honeycomb filter 3 is formed of a porous silicon carbide sintered body in a honeycomb shape and has a large number of gas passage holes extending in parallel to the axial direction. The supply side 4 and the discharge side 5 of each gas passage hole are formed. One end of is sealed alternately. Further, an oxidation catalyst composed of a platinum group element, another metal element and an oxide 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 wall portion of the gas passage hole and are oxidized by the oxidation catalyst. It Then, the purified exhaust gas is exhausted from the exhaust side 5 of the honeycomb filter-3.

When the honeycomb filter 3 used as described above is regenerated, the honeycomb filter 3 collects a predetermined amount of particulates, and then the burner 7 or the like is used. The heating of the honeycomb filter-3 is started by the hot air. Then, the particulates collected in the honeycomb filter-3 are burned and regenerated. Next, the structure of the honeycomb filter-3 will be described in detail. As shown in FIG. 2, in the present invention, the honeycomb filter 3 is formed by connecting a plurality of rectangular columnar divided portions 8 and 9 to each other by a seal material 10.

The divided portion 8 of the honeycomb filter 3 is a divided portion that constitutes a peripheral portion of the filter, and the supply-side end surface of the gas passage hole is sealed in a checkered pattern, and the supply side is not sealed. The discharge side of the gas passage hole is sealed. The divided portion 9 near the center of the honeycomb filter 3 is divided into a gas supply side (upstream side) 9a and a discharge side (downstream side) 9b. As shown in FIG. 3, the upstream divided portion 9a is a non-sealed body whose both end surfaces are not sealed, and the downstream divided portion 9b has one of the surfaces sealed like the peripheral divided portion. It is a sealed body. The ratio of the length (A) of the unsealed body on the upstream side of the central honeycomb filter to the length (B) of the sealed body on the downstream side is (A) / (B) = 4/1. And the other eight length ratios (A) / (B) = 2/1.

By adopting the above filter structure, the particulate collection density near the central portion becomes smaller than that at the outer peripheral portion, and the particulate accumulation amount near the central portion on the burner side is reduced. Since it becomes extremely small, there is no abnormal temperature rise part in the filter due to regeneration, and it is possible to prevent filter deterioration during regeneration processing.

[0016]

[Effect of device]

 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 parts, and the divided part near the center is divided into the upstream side and the downstream side. By using a non-sealed body, unlike the conventional one, the filter is not heated at the poles at all, deterioration of the filter is not caused, and the collected particulates are heated. Can be easily done with very small energy.

[Brief description of drawings]

FIG. 1 is an explanatory view of an exhaust gas purifying device 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 purifying device 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 the center 10 Seal material 9a upstream side Split part 9b Downstream split part

Claims (1)

[Scope of utility model registration request] 1. An exhaust gas purifying apparatus, comprising a casing filter provided in an exhaust pipe of an internal combustion engine, wherein a honeycomb filter made of a porous sintered body having a honeycomb shape with a large number of gas passage holes parallel to an axial direction is arranged. In the device, the honeycomb filter is composed of a plurality of divided portions, and the divided portion forming the vicinity of the central portion of the honeycomb filter is located in the upstream portion on the internal combustion engine side and the downstream portion on the exhaust gas discharge side. Divided, the gas passage hole in the upstream portion is not sealed at both end surfaces, the gas passage hole in the downstream portion is sealed at any one of the end surfaces, and the vicinity of the peripheral portion of the honeycomb filter. The exhaust gas purifying device is characterized in that one of the end faces of the gas passage hole is sealed in the divided portion.