JPH0861054A - Manufacture of emission controller - Google Patents

Abstract

PURPOSE: To obtain a manufacturing method for an emission controller in which a seramic monolith receiving a catalyst is inserted surely and simply in a prescribed position and fixed stably in a casing for constituting an exhaust gas smokeway. CONSTITUTION: In manufacturing an emission controller, in which a seramic monolith 1 for receiving a catalyst, is fixed in the exhaust gas smokeway, it is required that at first a seal material 2 covered by a synthetic resin film 3 on its both front and rear surfaces or outer periphry is wound up on the outer periphery of the seramic monolith 1 and then this seramic monolith 1 is inserted and fixed in the exhaust gas smokeway.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an exhaust gas purification device. More specifically, the present invention relates to a method for manufacturing an exhaust gas purification device in which a ceramic monolith is inserted into an exhaust gas flue by a sealing material and stably fixed.

[0002]

2. Description of the Related Art Conventionally, in order to suppress air pollution, as one of the methods for removing harmful components such as carbon monoxide, hydrocarbons and nitrogen oxides contained in exhaust gas of an internal combustion engine, heavy metals and Exhaust gas purifiers that use catalysts such as precious metals are used. This type of purification device is classified into the following two types. (1) Pellet catalyst type purification device in which a pellet-shaped catalyst in which a catalyst metal is supported on a granular carrier (generally ceramic is used) is housed in a metal case (2) A ceramic carrier having many exhaust gas passages inside a cylinder ( Hereinafter, this is referred to as "ceramic monolith") a purifying device in which a so-called integrated catalyst in which a catalytic metal is supported is held via a holding layer (see US Pat. No. 3,441,381 and US Pat. No. 3,441,382).

Among the above-mentioned conventional methods, the purifying apparatus using the integrated catalyst of (2) is suitable if the method of holding the catalyst is appropriate.
It is superior to (1) because the catalyst metal on the pellet surface is less likely to wear and dissipate like the pellet catalyst type purification device of (1), and the container used can be relatively small. . However, if the method of holding the catalyst in the purification device of (2) is not appropriate, the integrated catalyst is easily destroyed by the vibration during the operation of the internal combustion engine. In particular, when the exhaust gas is at a high temperature, the metal used for the container usually has a larger thermal expansion amount than that of the integrated catalyst, so that the holding force of the holding layer interposed between the container and the integrated catalyst becomes weak. The integrated catalyst is easily broken by vibration. Therefore, the holding force of the holding layer must be properly held even when the temperature is changed from low temperature to high temperature.

The performance required of the catalyst holder is as follows. (1) It is necessary that the holding force of the holding layer is durable, that is, the holding force of the holding layer is maintained even in a vibration state at high temperature. (2) The retention layer needs to have a density that does not allow exhaust gas to pass through so that the retention force does not decrease due to exhaust gas. A ceramic monolith having a large number of exhaust gas passages inside a cylinder has been proposed and put into practical use as a holding body having these properties (1) and (2). In the case where the purifying device is installed on an automobile, there is a problem that the monolith may be cracked or crushed by the impact load. In order to solve the problem of the brittleness of the ceramic monolith, many studies have been conducted in the past and various structures have been proposed.

For example, Japanese Patent Publication No. 58-17335,
Japanese Unexamined Patent Application Publication No. 1-240715 discloses a method of fixing a ceramic monolith of an integrated catalyst to a metal casing.
The outer side of the ceramic monolith is a ceramic fiber molding,
Alternatively, a technique has been proposed in which a ceramic expansive sheet material (which is referred to as a "sealing material") is coated. By coating the outside of the ceramic monolith in this way, it is possible to prevent cracks and fractures due to vibration and shock.

The following method is known for covering the outside with a sealing material and inserting and fixing it in the casing. (a) Stuffing method: A method in which a ceramic monolith coated with a sealing material is pushed into a metal casing. (b) Clam shell method: A method in which a ceramic monolith covered with a sealing material is sandwiched into a half-divided metal casing, and the half-divided metal casing is fixed by welding or the like. Whichever of these methods (a) and (b) is adopted, it is preferable to interpose a sealing material in order to prevent the ceramic monolith from moving in the metal casing. At this time, the thickness of the sealing material to be interposed must be equal to or slightly larger than the interval formed between the metal casing and the outside of the ceramic monolith. When inserting and fixing the ceramic monolith covered with such a seal material in the metal casing, in the method of (a), the surface of the seal material is damaged or the slip between the metal casing and the seal material is bad. If so, there is a problem that the sealing material is displaced and proper insertion / fixation cannot be performed. The method (b) has a problem that the sealing material easily protrudes and welding cannot be performed.

[0007]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention is to surely and easily insert a ceramic monolith containing a catalyst into a predetermined place in various metal casings constituting an exhaust gas flue. In addition, it is an object of the present invention to provide a method for manufacturing an exhaust gas purification device that is fixed stably.

[0008]

In order to solve the above-mentioned problems, in the invention described in claim 1 of the present invention,
In manufacturing an exhaust gas purifying device in which a ceramic monolith containing an exhaust gas purifying catalyst is fixed in the exhaust gas passage, first, a sealing material in which both the front and back surfaces or the outer periphery are covered with a synthetic resin film is applied to the ceramic monolith. The ceramic monolith is then wrapped around the outer circumference of the exhaust gas, and then the ceramic monolith is inserted and fixed in the exhaust gas flue.

The present invention will be described in detail below. In the present invention, the exhaust gas purifying device means a device for removing harmful components such as carbon monoxide, hydrocarbons, and nitrogen oxides in the exhaust gas of an internal combustion engine, in particular, an automobile. A ceramic monolith containing an exhaust gas purifying catalyst is fixed in the exhaust gas flue.

The ceramic monolith functions to hold a catalyst that is fixed in the exhaust gas flue and promotes a chemical reaction that converts harmful components in the exhaust gas into harmless ones. This ceramic monolith is made of a ceramic material. Types of ceramic materials include brittle refractory ceramic materials such as aluminum oxide, silicon dioxide, magnesium oxide, zirconia, silicon carbide, cordierite, and the like. The ceramic material is not limited to those exemplified above. Monoliths made of these ceramic materials have a plurality of gas permeable passages extending in the length direction from one end inlet to the other end outlet in the length direction. The monolith typically has an elliptical or circular cross-sectional shape in the direction perpendicular to the length direction, but is not limited to these shapes.

The exhaust gas purifying catalyst contained in the ceramic monolith has a function of promoting a chemical reaction for converting harmful components in the exhaust gas into harmless components. The catalyst may be any catalyst as long as it has a function of promoting a chemical reaction for converting a harmful component in exhaust gas into a harmless component, and is not limited to the kind. Further, the method of accommodating these catalysts in the ceramic monolith can also be based on the conventionally known method.

The sealing material in the present invention has a function of sealing the gap formed between the outer periphery of the ceramic monolith and the inner side of the metal casing. It is preferable that the sealing material has a property of not being decomposed or deteriorated by the temperature of the exhaust gas passing through the flue. Specifically, there are inorganic fibers and metal fibers. Examples of the types of inorganic fibers include alumina silicate fibers, asbestos fibers, glass fibers, zirconia-silica fibers, and crystalline alumina whiskers. These examples are not meant to limit the invention. These inorganic fibers are preferably formed into a mat shape. When molding the inorganic fibers into a mat, it is preferable to use a small amount of synthetic resin to bond the fibers together. It is preferable that these inorganic fibers have a small density, and the density is 0.10 to 1.0.
It is preferable to select in the range of g / cm ³ .

The synthetic resin film in the present invention has a function of covering the entire surface or the outer peripheral surface of the sealing material. The synthetic resin is not limited in its type as long as the film exhibits flexibility, and includes polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, polyamide, polystyrene, and polycarbonate. , Polyethylene terephthalate, and polybutylene terephthalate. There is no particular limitation on the film production method and thickness.

According to the method of the present invention, first, a sealing material having both front and back surfaces or outer periphery covered with a synthetic resin film is wrapped around the outer periphery of the ceramic monolith, and then the ceramic monolith is fixed in the exhaust gas flue. To do. If both sides of the sealing material or the outer circumference are covered with a synthetic resin film,
(a) When fixed by the stuffing method, it is slippery inside the metal casing, which facilitates insertion and movement to a predetermined position. Further, in the case of fixing the inside of the metal casing by the above-mentioned (b) clam shell method, the problem that the sealing material does not protrude and the welding cannot be performed is solved.

The method of the present invention will be described below with reference to the drawings, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. FIG. 1 shows an embodiment of the method of the present invention. FIG. 1 is a perspective view of a ceramic monolith before being coated with a sealing material, and FIG. 2 is a perspective view of a state after coating the ceramic monolith with a sealing material. FIG. 3 and FIG. 3 are perspective views of the ceramic monolith fixed to a metal casing. In the figure, 1 is a ceramic monolith, 2 is a sealing material, 3 is a synthetic resin film, and 4 is a metal casing.

When the ceramic monolith 1 is covered with the sealing material 2, a synthetic resin film 3 is arranged outside the sealing material 2 (see FIG. 1), and the sealing material 2 is wound around the surface of the monolith 1 while applying pressure. At this time, one end of the synthetic resin film 3 is adhered to the surface of the monolith 1 before winding, and the other end is adhered after winding the sealing material 2 around the surface of the monolith 1 (see FIG. 2). By inserting and fixing the monolith 1 covered with the sealing material 2 in the metal casing 4 in this manner, a desired exhaust gas purifying device can be obtained (see FIG. 3). The synthetic resin film 3 burns and disappears at a high temperature when the exhaust gas purifying device is first operated, but the purpose of using the synthetic resin film 3 is to securely insert and fix the monolith 1 into the metal casing 4. However, it may burn and disappear when it is first operated.

The method of the present invention has special advantageous effects as follows, and its industrial utility value is extremely large. 1. According to the method of the present invention, the ceramic monolith containing the catalyst can be easily and surely inserted into the metal casing at a predetermined position and stably fixed. 2. The exhaust gas purification device obtained by the method of the present invention,
Since the outer side of the ceramic monolith is covered with the sealing material, it is possible to prevent the occurrence of cracking / crushing due to impact load.

[Brief description of drawings]

FIG. 1 is a perspective view of a ceramic monolith before being covered with a sealing material.

FIG. 2 is a perspective view showing a state after the ceramic monolith is covered with a sealing material.

FIG. 3 shows a perspective view of a ceramic monolith fixed to a metal casing.

[Explanation of symbols] 1 ... Ceramic monolith 2 ... Sealing material 3 ... Synthetic resin film 4 ... Metal casing

Claims (1)

[Claims] 1. In manufacturing an exhaust gas purifying device in which a ceramic monolith containing an exhaust gas purifying catalyst is fixed in an exhaust gas flue, first, both front and back surfaces or outer periphery thereof are coated with a synthetic resin film. A method for manufacturing an exhaust gas purifying device, comprising: winding a sealing material around an outer periphery of a ceramic monolith, and then inserting and fixing the ceramic monolith into an exhaust gas flue.