JPS6257624A - Production of plug for waste gas filter - Google Patents

Abstract

PURPOSE:To increase the amt. of waste gas capable of passing the end face of a filter cell and to reduce the pressure drop by mixing a combustible granular substance and a raw ceramic material, baking the mixture and forming the title porous plug. CONSTITUTION:Polyvinyl alcohol, methyl cellulose and starch paste are added to a raw ceramic material such as porous ceramic calcined powder having specified composition, clay and fibrous ceramics to provide appropriate plasticity. The combustible granular substance of org. polymers such as polyethylene, polypropylene and polystyrene is mixed into the raw material to obtain a plug material. The material is packed into the opening of the end part of the cell and baked when the material is molded into a honeycomb body. The combustible granular substance is vanished by the baking and the vanished part is left as the void.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a plug for an exhaust gas filter that captures particulates whose main component is carbon (soot) contained in the exhaust gas of a diesel engine.

(Prior Art) Recently, ceramic filters with a honeycomb structure that have a high trapping effect and low pressure loss have been put into practical use as filters that deposit and capture carbon contained in exhaust gas from diesel engines.

The manufacturing method is 1. For example, a honeycomb structure is formed by extrusion using co-op yellow material as the main component, and then fired, and then a material with low porosity such as heat-resistant cement is used to form the edges of each cell that forms the honeycomb structure unit. the opening,
They are alternately filled and occluded as plugs. In such an exhaust gas filter, the material of the plug has a low porosity as shown in -F, so that the exhaust gas cannot pass through the plug portion.

(Problems to be Solved by the Invention) Generally, the lower the pressure loss of the exhaust gas filter of a diesel engine with respect to exhaust gas, the lighter the engine load and the higher the engine efficiency. However, if the plug lacks air permeability as described above, the area through which the exhaust gas can pass through at the exhaust gas inlet is about 172 mm of the end face of the exhaust gas filter, so the exhaust gas flow is constricted, resulting in a significant pressure loss.

In addition, carbon deposited in the exhaust gas filter is ignited and incinerated by the engine exhaust temperature or forced ignition means such as glow plugs, resulting in so-called regeneration. The amount of accumulation is a problem, and when the area through which exhaust gas passes is small as described above, there is also little carbon accumulation, so even if forced ignition is performed, the propagation of combustion will not spread, resulting in incomplete regeneration.

(Means for Solving the Problems) In order to eliminate the above-mentioned drawbacks, the present invention makes the plug porous to increase the passage of exhaust gas, reduce the pressure loss of the exhaust gas filter, and completely prevent regeneration. The present invention aims to provide a method for manufacturing an exhaust gas filter plug that enables the above-mentioned plug to be manufactured by mixing combustible particulate matter and ceramic raw material and firing the plug.

(Function) With the above configuration, the present invention increases the amount of exhaust gas that can pass through the cell end face of the exhaust gas filter, thereby reducing pressure loss, and at the same time increasing carbon deposition and improving regeneration. Be able to do it.

(Example) The present invention first involves adding polyvinyl alcohol, methyl cellulose,
Starch glue is added to give appropriate plasticity, and organic polymers such as polyethylene polypropylene and polystyrene of a specified particle size, natural polymers such as starch granules, or combustible granular substances such as carbon particles are mixed to form a plug. Prepare raw materials.

During the process of forming a honeycomb, this raw material is filled into the openings at the end of the cells and then fired. During this firing, the combustible particulate matter disappears, leaving traces of its disappearance as voids.

On the other hand, the ceramic raw material is fired while leaving voids where the particulate matter disappears, and is turned into a ceramic together with the honeycomb structure to produce an exhaust gas filter for a diesel engine equipped with a plug that allows exhaust gas to pass through. .

FIG. 1 is a sectional view of the exhaust gas filter manufactured as described above. Reference numeral 1 indicates the exhaust gas filter, 2 indicates the honeycomb structure, and 3 indicates the cell of the constituent unit. Plug 4
are alternately filled at every other end on one side of each cell 3. The exhaust gas passes through the inner wall of the cell 3 as indicated by the solid arrow and is discharged from the exhaust gas filter. The dashed arrow indicates the path of the exhaust gas through the porous plug 4 according to the invention.

By the way, when fiber ceramic is used as the main component, the fiber ceramic forms a crosslinked structure with each other, in addition to the effect of adding combustible particulate matter.

A plug with excellent exhaust gas permeability is manufactured.

Specific examples using fiber ceramic as the main material are shown below.

(Specific example 1) 20 parts by weight of fiber ceramic cut into 1mm+mm.

10 parts by weight of ceramic raw material powder consisting of sericite, alumina, and talc is suspended in 20 parts by weight of water.

1 part by weight of starch is added to this suspension and heated while stirring to gelatinize. Here, the starch glue is made by adding polyethylene powder type 1 with a primary particle size of 0.5 mm, which aggregates the fiber ceramic and the ceramic raw material powder and gives plasticity, and thoroughly stirs and mixes it to form the plug material raw material. Adjust.

The plug material raw material obtained in this manner was filled into the cell ends of the formed honeycomb structure, and then fired at 1350° C. to form a ceramic. The porosity of the plug was 50%.

(Specific Example 2) With the same ceramic raw material composition as in Specific Example 1, carbon particles with a particle size of 0.5 are mixed instead of polyethylene powder, and the porosity is improved by using a plug raw material that is made plastic with a methyl cellulose solution. 45% of the plugs were manufactured.

(Specific Example 3) A corrugated honeycomb structure was created using a sheet obtained by a papermaking method from 30 parts by weight of alumina-silica fibers, 16 parts by weight of a ceramic raw material mixed powder of sericite and petalite. 20 parts by weight of ceramic calcined powder with a particle size of 0.2 mm or less obtained by firing and pulverizing, 1 part by weight of starch, and 28 parts by weight of water are added and heated while stirring to gelatinize the starch. 10 starch granules
Add parts by weight and stir thoroughly to prepare plug raw material.

The plug raw material thus produced was filled into the cell ends of the above-mentioned corrugated honeycomb structure and fired at 1250°C. An exhaust gas filter with a plug having a porosity of 80% was formed.

(Specific Example 4) ``Bipods'' Plugs obtained from plug raw materials made with the same composition as in Specific Example 3, with 70 parts by weight of water and 35 parts by weight of polyethylene with particle size Q and 2 mm instead of starch grains had a low porosity. 9
It was 0%.

Specific examples have been described above, but if a plastic particulate material with a particle size of 1 square centimeter or more is used, the shrinkage becomes large during firing, resulting in insufficient bonding with the honeycomb structure.

(Effects of the Invention) As is clear from the above explanation, the present invention is a method for manufacturing a plug with high porosity, and is formed using a plug according to the present invention, particularly a plug having a length of 50 mm and a porosity of 50%. Exhaust gas filters can reduce pressure losses, thus reducing the load on the diesel engine. Furthermore, since the plug allows exhaust gas to pass through, a large amount of carbon accumulates on the plug surface, that is, on the filter end surface.

It facilitates ignition for forced regeneration using glow plugs, etc., and at the same time provides excellent effects such as complete combustion.

[Brief explanation of the drawing]

The figure is a sectional view showing an exhaust gas filter in which the present invention is used. 1...Exhaust gas filter, 2...Honeycomb structure, 3...Cell, 4...Plug. Patent applicant Matsushita Electric Industrial Co., Ltd. Tsuchigami... 4 works〃゛Sphy) Letter 2...Ha≦≠tA Tenzou 3...HitV 4...P9 Love

Claims (4)

[Claims] (1) In a diesel exhaust gas filter that has a structure in which the ends of a plurality of cells forming a honeycomb structure made of porous ceramic are alternately closed with plugs and the exhaust gas is passed through the cell walls, combustible particulate matter and A method for producing a plug for an exhaust gas filter, characterized in that a porous plug through which exhaust gas can easily pass is obtained by filling the end of the cell with a mixture with a ceramic raw material and then firing the mixture. (2) The method for manufacturing a plug for an exhaust gas filter according to claim (1), wherein the combustible particulate material is made of an organic polymer having a particle size of 1 mm or less. (3) The method for manufacturing a plug for an exhaust gas filter according to claim (1), wherein the combustible particulate matter is composed of carbon particles having a particle size of 1 mm or less. (4) The method for producing a plug for an exhaust gas filter according to claim (1), wherein the ceramic raw material is mainly composed of fiber ceramic.