Honeycomb filter for purifying exhaust gas

Abstract

An object of the present invention is to provide a honeycomb filter for purifying exhaust gases having a structure in that, even when comparatively large sealing material layer is included therein, there is hardly any increase in the amount of organic components contained in exhaust gases to be discharged. The present invention provides a honeycomb filter for purifying exhaust gases, having a structure in that a sealing material layer is formed on a circumference of a columnar body made of porous ceramics, which has a number of through holes placed in parallel with one another in the length direction with wall portion interposed therebetween, and the wall portion which separate the through holes from each other functions as a filter for collecting particulates, wherein the rate Sα of an area occupied by the sealing material layers to the total area of a cross-section including the through holes in the direction perpendicular to the through holes is set to 0.5% or more, and the rate Vα of organic components to the honeycomb filter for purifying exhaust gases is set to 0.5% by weight or less.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims benefit of priority to Japanese Patent Application No. 2002-81237, filed on Mar. 22, 2002, the contents of which are incorporated by reference herein. TECHNICAL FIELD [0002] The present invention relates to a honeycomb filter for purifying exhaust gases that is used as a filter for removing particulates and the like contained in exhaust gases discharged from an internal combustion engine such as a diesel engine or the like. BACKGROUND ART [0003] In recent years, particulates contained in exhaust gases that are discharged from internal combustion engines of vehicles, such as buses, trucks and the like, and construction machines have raised serious problems since those particulates are harmful to the environment and the human body. [0004] For this reason, there have been proposed various ceramic filters that allow exhaust gases to pass through porous ceramics and collect particulates in the exhaust gases to purify t...

AI Technical Summary

Benefits of technology

[0017] The present invention is made to solve the above problems, and its object is to provide a honeycomb filter for purifying exhaust gases having a structure in that, even when comparatively large sealing material layer is included therein, there is hardly any increase in the amount of organic components contained in exhaust gases to be discharged.

[0018] According to a first aspect of the present invention, a honeycomb filter for purifying exhaust gases has a structure in which: a columnar body made of porous ceramic comprises a number of through holes, the above mentioned through holes being placed in parallel with one another in the length direction with wall portion interposed therebetween; a sealing material layer is formed on a circumference portion of the above mentioned columnar body; and the above mentioned wall portion which separates the above mentioned through holes functions as a filter for collecting particulates wherein a rate Sα of an area occupied by the sealing material layers to the total area of across-section including the through holes in the direction perpendicular to the through holes, in the above mentioned honeycomb filter for purifying exhaust gases, is set to 0.5% or more, and a rate Vα of organic components to the honeycomb filter for purifying exhaust gases is set to 0.5% by weight or less.

[0019] Moreover, according to a second aspect of the present invention, a honeycomb filter for purifying exhaust gases has a structure in which: a plurality of a columnar porous ceramic member are combined with one another through a sealing material layer to form a ceramic block, each of the above mentioned columnar porous ceramic member comprising a number of through holes, the above mentioned through holes being placed in parallel with one another in the length direction with partition wall interposed therebetween; a sealing material layer is formed on a circumference portion of the above mentioned ceramic block; and the above mentioned partition wall which separates the above mentioned through holes functions as a filter for collecting particulates, wherein a rate Sβ of an area occupied by the sealing material layers to the total area of a cross-section including the through holes in the direction perpendicular to the through holes, in the above mentioned honeycomb filter for purifying exhaust gases, is set to 2% or more, and a rate Vβ of organic components to the above mentioned honeycomb filter for purifying exhaust gases is set to 0.5% by weight or less.

[0020] In the following description, the honeycomb filter for purifying exhaust gases according to the first aspect of the present invention is simply referred to as the honeycomb filter according to the first aspect of the present invention, and the honeycomb filter for purifying exhaust gases according to the second aspect of the present invention is simply referred to as the honeycomb filter according to the second aspect of the present invention. When the two are not particularly distinguished, each of these is also simply referred to as the honeycomb filter of the present invention.

Problems solved by technology

In recent years, particulates contained in exhaust gases that are discharged from internal combustion engines of vehicles, such as buses, trucks and the like, and construction machines have raised serious problems since those particulates are harmful to the environment and the human body.

In this arrangement, however, since the sealing material layer of the conventional honeycomb filter contains a comparatively large amount of organic components, in the case of a honeycomb filter in which sealing material layers account for a great ratio, it contains a large amount of organic components.

However, conventional honeycomb filters have failed to sufficiently decompose and eliminate the organic components by using the above-mentioned catalyst.

Images