JP3403232B2 - Exhaust gas purification converter and method of attaching heat insulating seal material to the converter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a converter for purifying exhaust gas and a method for mounting a heat insulating sealant for the converter, and more particularly to a method for assembling a sealant between the periphery of a catalyst holder and a shell.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, in an exhaust gas purifying converter 9 mainly mounted in a vehicle,
A catalyst holder 94, a metal shell 92 covering the outside of the catalyst holder 94, and a cushioning sealant 93 arranged between the two.
And consists of. The catalyst holder 94 carries a catalyst such as platinum. As the catalyst holder 94, for example, a cordierite carrier having a honeycomb cross section is used. In FIG. 4, reference numeral 910 is the exhaust pipe 95.
It is a mounting flange.

Next, as the cushioning sealing material 93, as shown in FIG. 5, an inorganic sheet 932 having an outer peripheral portion reinforced by a metal net 931 is used. The inorganic sheet 932 is formed by molding a mixture of vermiculite and ceramic fibers into a sheet. The cushioning sealing material 93 prevents damage when the catalyst holder 94 comes into contact with the metal shell on the outer periphery while the vehicle is running, etc.
It is used to prevent the exhaust gas from leaking from between the catalyst holder 94 and the catalyst holder 94. In addition, in recent years metal net 9
A converter using only the inorganic sheet 932 without using 31 is also used.

[0004]

However, the vermiculite used in the buffer sealing material 93 is
At high temperature of the exhaust gas, the water contained therein gradually evaporates. Therefore, the expansion pressure of the cushioning sealant is lowered during long-term use. Therefore, a gap is formed between the shell 92 and the catalyst holder 94,
The cushioning property and the sealing property are deteriorated. Especially, in the case of vermiculite, when the temperature exceeds 850 ° C., the above water evaporation is remarkable. Further, in a lean burn engine which has been widely used for improving fuel efficiency in recent years, the exhaust gas temperature may exceed 950 ° C. Therefore, the decrease in the expansion pressure of vermiculite becomes a problem.

Therefore, it is conceivable to use a buffer seal material having a ceramic fiber layer which is excellent in heat resistance and does not lower the expansion pressure. In this case, as shown in FIG. 6, the periphery of the catalyst holder 94 is covered with a ceramic fiber layer 96 like a futon to bury them between the upper shell 921 and the lower shell 922. is there. However, ceramic fibers are very brittle materials. Therefore, as shown in FIG.
When the ceramic fiber layer 96 is assembled between the first and lower shells 922 and the catalyst support 94, if a strong force is applied or a rubbing is performed, the powder is easily pulverized. Particularly, as described above, when the catalyst holder 94 covered with the ceramic fiber layer 96 is forcibly inserted between the lower shell 922 and the upper shell 921, the corner portions 920 of both shells and the ceramic fiber layer At the contact portion 961 of the
Therefore, the ceramic fiber layer in the above-mentioned collapses and cannot serve as a cushioning sealant.

Therefore, a conventional sealing material using vermiculite ((trade name: Interram Mat (manufactured by 3M),
In Ibi wool flex (made by Ibiden),
A binder such as emulsion latex was added to ceramic fiber and vermiculite to perform wet papermaking and molding, and then steps such as pressure pressing and drying were taken to reduce the thickness when setting, and it was usually easy to attach to an exhaust gas converter. However, not only the heat resistance problem, but also the manufacturing cost is high because of complicated steps.

In view of the above problems, the present invention provides an exhaust gas purifying converter heat insulating seal member which can be assembled at a low cost without deterioration of the seal layer at high temperature and without damaging the seal layer. It is intended to provide a method.

[0008]

SUMMARY OF THE INVENTION The present invention is directed to a catalyst support and
A shell that covers the outside of the catalyst holder and is placed between the shell and the shell.
Exhaust gas for automobiles consisting of a ceramic fiber layer
In the converter for purification, the ceramic fiber layer has a non-woven fabric of alumina fibers arranged on the catalyst holder side,
It has a double structure consisting of a silica-alumina fiber non-woven fabric on the shell side, and also has an airtight sheet or heat fusion.
The film is vacuum-coated with a film and has a bulk density of 0 when closed under vacuum.
10 to 0.40 g / cm ³ of the catalyst support and the shell
A converter for purifying exhaust gas for automobiles, which has a thickness of 1.0 to 2.5 times the clearance after assembly . The present invention also provides a catalyst holder and a catalyst holder
The shell that covers the outside and the ceramic foil placed between the two
Exhaust gas purification converter made of fiber layer
In the method of attaching the heat insulating sealing material, a non-woven fabric of alumina fiber is arranged on the catalyst holder side and silica-on the shell side.
A plate-like structure with a double structure composed of non-woven alumina fibers
The ceramic fiber non-woven fabric in the airtight sheet
Put it in and decompress the inside, or sandwich the top and bottom with a heat fusion film
The thickness is reduced by airtightly sealing with a vacuum.
The bulk density of the Kufiber layer is 0.10 to 0.40 g / cm ³ .
And after assembling the catalyst holder and the shell
The thickness is 1.0 to 2.5 times the clearance of
The sheet is sealed and then the vacuum sealed cell
A Mick fiber layer between the catalyst support and the shell
It is a method for attaching a heat-insulating sealing material to an automobile exhaust gas purifying converter, which is characterized in that the heat-insulating sealing material is installed in the vehicle.

First, for example, a honeycomb-shaped member is used as the catalyst holder. The catalyst holder is made of cordierite, alumina, chromium-based stainless steel, or the like. In addition, the shell is, for example, a cylinder having an oval or circular cross section. The shell is made of metal, for example. Further, the airtight sheet covers the ceramic fiber layer and, as described later, in order to easily bury the ceramic fiber between the shells or to easily wind the ceramic fiber around the catalyst holder. It was used. Further, the converter having the above structure is connected to an exhaust gas pipe in an automobile manufacturing plant. Then, at the time of test operation, the airtight sheet is incinerated due to the high temperature exhaust gas. Alternatively, the airtight sheet may be incinerated before connecting the converter to the exhaust gas pipe.

Next, in the production of the ceramic fiber layer, the plate-shaped ceramic fibers are put into a bag made of an airtight sheet to form a fiber seal body, and then the inside of the fiber seal body is decompressed to be airtight. The opening of the sheet is pasted with hot melt or an adhesive to completely seal it. Alternatively, the above ceramic fibers are sandwiched by heat-sealing films from above and below, and then the periphery of the ceramic fiber layers is bonded by hot melt while decompressing the inside, and completely sealed to form a fiber seal body. This reduces the thickness of the ceramic fiber layer.

The thickness of the fiber seal body before assembly is 1.0 to the clearance between the catalyst holder and the shell.
It must be 2.5 times thicker. If the thickness of the fiber seal body before assembly is less than 1 time the clearance, that is, if it is thin, the position of the catalyst holder may be misaligned during handling and transportation after the converter is assembled, and rarely in the case of a ceramic catalyst holder. This is because it will be damaged. Further, when the thickness exceeds 2.5 times, as described above, not only the workability of assembling becomes extremely poor, but also the ceramic fiber layer is broken.

Further, the bulk density of the ceramic fiber when sealed under reduced pressure must be in the range of 0.10 to 0.40 g / cm ³ . If the bulk density is too small, the restoring force of the ceramic fiber is weak, and the catalyst holder 4 dances due to engine vibration or running vibration of the automobile, the ceramic fiber layer is not only powdered or abraded, but the exhaust gas is This is because it penetrates the fiber layer. On the contrary, if the bulk density is too large, the ceramic fiber itself will be crushed by the pressure at the time of pressurizing and assembling in the subsequent step, or the catalyst holder will be damaged or deformed.

Next, the ceramic fiber thinned by the airtight sheet is sprinkled on the catalyst holder, and then the upper shell and the lower shell are contacted and pressed from above and below to bring the upper shell and the lower shell into close contact with each other. Clinch the outer peripheral part of or fix it with bolts and nuts.

Next, as described above, the airtight sheet may be heated and incinerated after the production of the exhaust gas purifying converter is completed. Further, even when the converter for purifying exhaust gas is assembled to a vehicle or the like, part or all of the airtight sheet may remain.

It is preferable that the ceramic fiber is made of a material selected from alumina fiber, silica-alumina fiber and silica fiber non-woven fabric. All of these are substances having excellent heat resistance. Further, considering the material cost, the above-mentioned ceramic fiber is provided with alumina fiber which is expensive but more excellent in heat resistance on the side of the catalyst support which becomes high temperature, and is slightly inferior in heat resistance on the low temperature side outside thereof but is inexpensive. It may have a two-layer structure in which silica-alumina fibers are arranged.

The airtight sheet is made of silicone resin,
An organic synthetic sheet such as polyvinyl chloride, polyethylene, or ionomer resin is used. In particular, in order to more easily assemble the fiber seal body in the shell, it is preferable that the surface of the airtight sheet has good lubricity. That is, the airtight sheet is preferably made of a material having a low surface friction coefficient. From this point of view, polyvinyl chloride, polyethylene and ionomer resins are most preferable among the above materials for the airtight sheet. It is also effective to coat the outer surface of the airtight sheet with lubricating oil or the like to increase the lubricity.

[0017]

In the converter for purifying exhaust gas according to the manufacturing method of the present invention, the ceramic fiber layer is provided as the seal layer between the catalyst holder and the shell. The ceramic fiber layer has excellent heat resistance. Therefore, even if the ceramic fiber layer is exposed to exhaust gas, especially high-temperature lean burn exhaust gas, it may be deformed due to a decrease in expansion pressure and deteriorate in quality like a conventional buffer seal material made of vermiculite. Absent.

In the manufacturing method of the present invention, the ceramic fiber in the converter for purifying exhaust gas is covered with an airtight sheet, and the inside of the airtight sheet is depressurized. Therefore, the thickness of the ceramic fiber is reduced, and the thickness is equal to or larger than the space between the catalyst holder and the shell by 150%. Therefore, the ceramic fiber layer can be reliably and easily assembled between the shell and the catalyst holder without requiring complicated steps, and can be handled and transported after the exhaust gas purifying converter is assembled. Even if
The catalyst support does not move or break within the shell. Thus, the brittle ceramic fiber layer can be easily assembled in the shell without damaging it.

As described above, according to the present invention, an exhaust gas purifying converter in which the seal layer does not deteriorate at high temperatures can be assembled easily at low cost without damaging the seal layer.

[0020]

【Example】

(Embodiment 1) First, an exhaust gas purifying converter manufactured according to an embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the exhaust gas purifying converter 1 of this example includes a catalyst holder 4, a shell 2 that covers the outside of the catalyst holder 4, and a ceramic fiber layer 31 disposed between the catalyst holder 4 and the shell 2. , The ceramic fiber layer 31
Are covered with an airtight sheet 32. The ceramic fiber layer 31 has a two-layer structure of alumina fiber on the catalyst support 4 side and silica-alumina ceramic fiber on the shell side, the airtight sheet 32 is polyethylene, and the catalyst support 4 is cordierite. The reference numeral 39 indicates the ceramic fiber layer 3
It is a seam generated when 1 is arranged. The shell 2 includes an upper shell 21 and a lower shell 22. Above upper shell 2
Both 1 and the lower shell 22 are shells having a semi-elliptical cross section. Flange 2 with bolt holes 211 at both ends
10, 220 are provided. The catalyst holder 4 is a honeycomb body having a lattice-shaped cross section. The cross section is an ellipse, and its size is 150 mm in major axis and 100 in minor axis.
mm. In the exhaust gas purifying converter 1 of this example, a ceramic fiber layer 31 is provided as a seal layer between the catalyst holder 4 and the shell 2. In addition, the ceramic fiber layer 31 is an airtight sheet 32.
It is covered with. As a result, the ceramic fiber layer 31 has excellent heat resistance, but is brittle and weak against friction and the like.
Can be assembled in the shell 2 without damage. Therefore, the ceramic fiber layer 31 of this example is
Even when exposed to exhaust gas, particularly high-temperature lean burn exhaust gas, deformation and quality deterioration due to a decrease in expansion pressure unlike conventional buffer seal materials made of vermiculite do not occur.

Next, a method of manufacturing the exhaust gas purifying converter of the present invention will be described. As shown in FIG. 2A, a plate-shaped ceramic fiber 31 having a short side of 100 mm, a long side of 400 mm, a thickness of 25 mm, and a bulk density of 0.10 g / cm ^3.
To prepare. The ceramic fiber 31 is provided at its end with a concave engaging portion 310 and a convex engaging portion 311 to be engaged with the concave engaging portion 310. On the other hand, as shown in FIG. 2B, a heat fusion film 32 made of polyethylene is prepared. Then, as shown in FIG. 2C, the ceramic fiber 31 is sandwiched between the heat-sealing films 32 from above and below,
The inside of this is decompressed by a vacuum packing device, and at the same time, the film 32 around the ceramic fiber 31 is bonded by hot melt and completely sealed. Then, the excess portion of the film is cut. As a result, as shown in FIG. 2D, the thickness of the ceramic fiber 31 is reduced, the thickness is 10 mm, and the bulk density is 0.25 g / cm ^3.
A fiber seal body 3 is formed. Then, the outer surface of the fiber seal body 3 was coated with a lubricating oil. Next, as shown in FIG. 3 (A), the catalyst holder 4 is placed on the fiber seal body 3. Then, FIG. 3 (B)
As shown in FIG.
Around the circumference of the ring. At this time, the concave engaging portions 310 and the convex engaging portions 31 at both ends of the ceramic fiber 31 are
1 mesh with each other. This portion is the seam 39. Next, as shown in FIG. 3C, the fiber seal body 3 is placed on the upper portion of the lower shell 22. Further, the upper shell 21 is placed on the fiber seal body 3 and pressed. afterwards,
A bolt is inserted into the bolt hole of the flange to fix the upper shell 21 and the lower shell 22 (Fig. 1). As described above, according to this embodiment, the ceramic fiber 31 can be easily attached to the shell 2 without damaging the ceramic fiber 31.
And the catalyst holder 4 can be attached, and the exhaust gas purifying converter 1 can be easily manufactured.
The clearance between the catalyst holder 4 and the shell 2 at this time is 6 mm.

[Brief description of drawings]

FIG. 1 is a sectional perspective view of an exhaust gas purifying converter manufactured according to the present invention.

FIG. 2 is an explanatory diagram of a manufacturing method according to the first embodiment.

FIG. 3 is an explanatory view of the manufacturing method of Example 1 following FIG.

FIG. 4 is a vertical cross-sectional view of a conventional exhaust gas purification converter.

FIG. 5 is a configuration diagram of a buffer seal material of a conventional exhaust gas purification converter.

FIG. 6 is an explanatory diagram relating to conventional attachment of a cushioning seal material.

FIG. 7 is an explanatory view of a problem regarding attachment of a cushioning seal material, following FIG. 6;

[Explanation of symbols]

1: Exhaust gas purification converter 2: Shell 21:
Upper shell 22: Lower shell 3: Fiber seal
31: Ceramic fiber layer 32: Airtight sheet
4: Catalyst support

─────────────────────────────────────────────────── --- Continued from the front page (56) Reference JP-A-50-112615 (JP, A) JP-A-59-126023 (JP, A) JP-A-53-110712 (JP, A) JP-A-62-1 67215 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F01N 3/28 F01N 7/14

Claims (2)

(57) [Claims] 1.Covering the catalyst holder and the outside of the catalyst holder
Shell and ceramic fiber layer placed between them
Consists of a converter for purifying exhaust gas for automobiles
hand,The ceramic fiber layer is attached to the catalyst holder side.
Laminated non-woven fabric of Lumina fiber, silica-aluminum on the shell side
As a double structure with a non-woven fabricNaruto
, Coated with an airtight sheet or heat-sealing film under reduced pressure.
And has a bulk density of 0.10 to 0.40 g / cm when closed under reduced pressure
³ Then, after the catalyst holder and the shell are assembled,
It has 1.0 to 2.5 times the thickness of AlanceCharacterized by
Exhaust gas purification converter for automobiles. 2.Covering the catalyst holder and the outside of the catalyst holder
Shell and ceramic fiber layer placed between them
A heat-insulating converter for automobile exhaust gas purification
In the installation method of the reel material, Alumina fiber non-woven fabric is placed on the catalyst holder side, and the shell side
Double structure consisting of silica-alumina fiber non-woven fabric
age,A plate-shaped ceramic fiber non-woven fabric is
Put in a container to reduce the pressure inside, or with a heat-sealing film.
The thickness is reduced by sandwiching the top and bottom and reducing the pressure,
The ceramic fiber layer has a bulk density of 0.10 to 0.40 g.
/cm ³ In addition, the catalyst holder and the shell
The thickness was 1.0 to 2.5 times the clearance after assembly.
After sealing the airtight sheet, Then, this vacuum-sealed ceramic fiber
A layer is placed between the catalyst support and the shell and the pressure assembly
Attach Characterized by the fact that
How to install the heat insulating sealant on the inverter.