JPH018650Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a holding device for a monolithic catalyst, and particularly relates to an improvement of a sealing member interposed between a casing and a monolithic catalyst.

(Prior Art) A monolithic catalyst formed in a honeycomb shape of alumina or the like has been known as one of the catalysts for purifying engine exhaust gas. Since this monolithic catalyst is very fragile, it is necessary to hold it in the casing via an elastic sealing member that also serves as a catalyst holding and sealing member. Steel wool, ceramic wool, or the like is generally used as this type of sealing member, but when used for a long period of time, these materials deteriorate due to heat and lose their elasticity, reducing their ability to retain the catalyst. For this reason, there was a problem in that the monolithic catalyst would shift due to back pressure or the like, and its ends would be easily damaged.

In order to solve this problem, as seen in Japanese Patent Application Laid-Open No. 57-81112, a sealing member is formed from a heat-resistant material including a thermally foamable material such as vermiculite, and the sealing member is expanded by the heat of the exhaust gas. Several methods have been developed that attempt to achieve catalyst retention and sealing. This seal member can be easily and inexpensively manufactured by forming a sheet of an appropriate thickness by alternately layering a heat-foamable member and heat-resistant fibers such as ceramic. However, with this structure in which simply stacked layers are interposed between the casing and the monolith catalyst, thermally foamable materials such as vermiculite are likely to be blown away by the gas pressure during use, which causes The problem remained that the sealing performance and catalyst retention effect deteriorated.

(Purpose of the invention) The present invention is intended to eliminate such conventional drawbacks, and uses a sealing member made of a heat-resistant material containing a thermally foamable substance to improve sealing performance and catalyst retention, and to improve sealing performance and catalyst retention. Provided is a monolithic catalyst holding device that can reliably prevent thermally foamable substances from being blown away by gas pressure and maintain the function of a sealing member over a long period of time while making the member easy to manufacture. It is something to do.

(Structure of the invention) The present invention is a monolithic catalyst holding device in which a monolithic catalyst is held in a casing via a sealing member, in which the sealing member is composed of layers of heat-resistant fibers and a thermally foamable member. The catalyst is characterized in that the seal is rolled to form a roll shape in cross section along the axial direction of the catalyst. Ceramic fiber or the like is used as the heat-resistant fiber, and vermiculite, mica, or the like is used as the heat-foamable material.

(Example) FIGS. 1 and 2 show the overall structure of a catalytic converter. In these figures, 1 is a cylindrical casing, and flanges 2 connected to an exhaust pipe (not shown) are attached to the openings at both ends of the casing, and two monolithic catalysts are installed inside the casing 1. 3 and 4 are installed in series. The monolithic catalyst 3 located on the left side in the figure has a flange portion 5a of an internal frame 5 provided at an end inside the casing 1, and a ring-shaped buffer member 7 supported by a spacer 6 at an intermediate portion inside the casing 1. Furthermore, the monolithic catalyst 4 on the right side is held between the spacer 6 and a ring-shaped buffer member 8 supported by the stepped portion of the casing 1, and is positioned in the axial direction. There is. The buffer members 7 and 8 are made of steel wool, ceramic wool, or the like.

The outer periphery of the monolithic catalysts 3 and 4 and the casing 1
Seal members 10 and 11 containing a thermally foamable member, which will be described in detail later, are interposed between the two. In the embodiment shown in the figure, in order to save material costs, the sealing members 10 and 11 are interposed only in a predetermined area corresponding to the rear end (right end in the figure) of each monolithic catalyst 3 and 4, and Elastic material such as steel wool 1
2 and 13 fill the space between the casing 1 and the monolith catalysts 3 and 4.

The seal members 10 and 11 are shown in FIGS. 3 and 4.
The structure is as shown in the figure. That is, a sheet 15 is formed in advance, in which heat-resistant fiber layers 16 made of ceramic fibers and layers of heat-foamable material 17 such as vermiculite are alternately stacked (see FIG. 4), and this sheet 15 is coated with a catalyst. It is placed between the casing 1 and the monolithic catalysts 3 and 4 in a rolled state so as to form a roll when viewed in cross section along the axial direction (see FIG. 3). The seal members 10 and 11 are formed in this way.

According to this holding device, when the seal members 10 and 11 are heated by the exhaust gas, the thermally foamable member 17 foams, so that the seal member 1
0 and 11 expand and come into pressure contact with the inner surface of the casing 1 and the outer peripheral surfaces of the monolithic catalysts 3 and 4 to securely hold the monolithic catalysts 3 and 4. In addition, the seal member 1
0 and 11 are wound into a roll, several heat-resistant fiber layers 16 exist also in the direction perpendicular to the exhaust gas flow direction, and this acts as a barrier.
Thermal foam member 17 is prevented from being blown away by the exhaust gas stream.

(Effects of the invention) In the present invention as described above, the sealing member interposed between the casing and the monolithic catalyst is made of a sheet made of heat-resistant fibers and a thermally foamable material wrapped in layers, and is arranged in the axial direction of the catalyst. Since it is formed in a roll shape with a straight cross section, it has excellent sealing properties and monolithic catalyst retention effect, and is easy to manufacture.Moreover, the thermally foamable member is particularly resistant to being blown away by exhaust gas pressure. It is possible to reliably prevent this.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view of a catalytic converter showing an embodiment of the present invention, Fig. 2 is a horizontal sectional view, Fig. 3 is an enlarged sectional view of the main parts, and Fig. 4 shows the structure of the seal member. It is an enlarged sectional view. 1... Casing, 3, 4... Monolith catalyst, 1
0, 11...Sealing member, 16...Heat-resistant fiber layer, 1
7...Thermofoamable member.

Claims (1)

[Scope of utility model registration request] In a monolithic catalyst holding device in which a monolithic catalyst is held within a casing via a sealing member, the sealing member wraps a seal made of layered heat-resistant fibers and a thermally foamable member, and A holding device for a monolithic catalyst, characterized in that it is formed in a roll shape with a cross section along the .