JP3341022B2 - How to install a converter heat-insulating sealing material for automotive exhaust gas purification - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
It comprises a catalyst holder 94, a metal shell 92 covering the outside of the catalyst holder 94, and a cushioning member 931 and a sealing member 932 arranged between the two. The catalyst holder 94 carries a catalyst such as platinum. As the catalyst holder 94, for example, a cordierite carrier whose cross section is formed into a honeycomb shape is used. In FIG. 4, reference numeral 910 is a flange for attaching the exhaust pipe 95.

[0005] Next, as the cushioning member 931, a knitted metal net is used. The sealing material 932 is usually an inorganic sheet, and is formed by molding a mixture of vermiculite and ceramic fibers into a sheet. The cushioning member 931 prevents the catalyst holder 94 from being damaged when the catalyst holder 94 comes into contact with a metal shell on the outer periphery, such as during running of an automobile. It is used to prevent the exhaust gas from leaking from. In recent years, a converter called a total mount system using only the inorganic sheet 932 without using the metal net 931 has been used. On the other hand, a total mount system using only an inorganic fibrous nonwoven fabric such as crystalline alumina fiber or ceramic fiber has been used due to a problem such as heat setting of a metal net due to a high exhaust gas temperature. I have.

[0004]

However, the above-mentioned inorganic fibrous nonwoven fabric is extremely excellent as a cushioning material, but when the automobile is running, that is, when the converter is heated, the metallic shell moves in the outer circumferential direction. The catalyst carrier thermally expands and hardly expands due to the ceramic material. Therefore, the clearance between the two increases, and the sealing performance of the exhaust gas deteriorates. For this reason, it is necessary to use the sealing material 932 together, but there is a problem in workability such as alignment of two kinds of materials.

Further, as shown in FIG. 5, the periphery of the catalyst holder 94 is covered like a futon with an inorganic fibrous nonwoven fabric layer 96, and these are buried between the upper shell 921 and the lower shell 922. In such cases, there were the following problems. That is, the ceramic fiber is a very brittle substance. For this reason, as shown in FIG. 6, when the inorganic fibrous nonwoven fabric layer 96 is incorporated between the upper shell 921 and the lower shell 922 and the catalyst holder 94, if a strong force is applied or rubbed, the powder is easily formed. It will be. In particular, as described above, when the periphery of the catalyst holding body 94 covered with the inorganic fibrous nonwoven fabric layer 96 is forcibly inserted between the lower shell 922 and the upper shell 921, the corners 920 of both shells and the inorganic shell 920 are removed. Significant friction and pressing force act on the abutting portion 961 of the fibrous nonwoven fabric layer, and the inorganic fibrous nonwoven fabric layer at the abutting portion 961 collapses, and does not serve as a cushioning seal material.

SUMMARY OF THE INVENTION In view of the foregoing problems, the present invention provides an exhaust gas purifying method which can maintain a sealing property without deterioration of a buffer layer at a high temperature and without damaging the buffer layer, and can be assembled at low cost. It is an object of the present invention to provide a method for attaching a converter heat insulating seal material.

[0007]

SUMMARY OF THE INVENTION The present invention provides a vehicle exhaust gas comprising a catalyst support, a shell covering the outside of the catalyst support, an inorganic fibrous non-woven fabric layer and a seal material disposed therebetween. In the method of mounting the heat-insulating sealing material for the converter, the plate-shaped inorganic fibrous nonwoven fabric and the sealing material are simultaneously placed in an airtight sheet, and the inside is reduced in pressure to reduce the thickness. 0.1 density
0 to 0.40 g / cm ^3, and the clearance after assembling the catalyst support and the shell is 1.0 to 0.4 g / cm ^3.
After the thickness is set to 2.5 times, the hermetic sheet is sealed, and then the reduced-pressure-sealed inorganic fibrous nonwoven fabric layer and the sealing ceramic fiber are arranged between the catalyst holder and the shell. The present invention relates to a method of attaching a heat insulating sealing material for a converter for purifying exhaust gas for automobiles, which is characterized by being attached. Further, the airtight sheet is made of an organic synthetic sheet such as polyvinyl chloride, polyethylene, ionomer resin or the like.

First, for example, a honeycomb-shaped support is used as the catalyst support. The catalyst support is made of, for example, cordierite, alumina or chromium-based stainless steel. The shell is, for example, an elliptical or circular tube having a cross section. The shell is made of, for example, metal. In addition, the airtight sheet covers the inorganic fibrous nonwoven fabric and the sealing material, and is used for easily burying the inorganic fibrous nonwoven fabric layer and the sealing material between the shells, or as described below. This is used to easily wind the porous nonwoven fabric and the sealing material around the catalyst holder. Further, the converter having the above structure is connected to an exhaust gas pipe in an automobile manufacturing plant. Then, during the test operation, the airtight sheet is incinerated by high-temperature exhaust gas. Alternatively, the airtight sheet may be incinerated before connecting the converter to the exhaust gas pipe. Next, as the sealing material, a known heat-expandable sheet (trade name: Interrammat, manufactured by 3M), inorganic fiber rope, cloth, or the like can be used as it is.

Next, in the production of the inorganic fibrous nonwoven fabric layer and the sealing material, the plate-like inorganic fibrous nonwoven fabric and the sealing material are arranged side by side, put in a bag made of an airtight sheet, and formed into a fiber sealing body. The inside of the fiber seal is depressurized, and the opening of the airtight sheet is bonded with a hot melt, an adhesive, or the like, and completely sealed. Alternatively, the above-arranged inorganic fibrous nonwoven fabric and the sealing material are sandwiched from above and below by a heat-sealing film, and then the inside of the inorganic fibrous nonwoven fabric and the sealing material are adhered to each other by hot melt while depressurizing the inside, and the fiber is completely sealed. Make a seal. Thereby, the thickness of the inorganic fibrous nonwoven fabric is reduced.

The thickness of the fiber seal before the assembly is 1.0 to 1.0 of the clearance between the catalyst support and the shell.
It must be 2.5 times thicker. If the thickness of the fiber seal before assembly is less than 1 time of the clearance, that is, thin, the position of the catalyst holder is shifted during handling and transportation after assembling the converter, and in the case of a ceramic catalyst holder, it is rare. Is to be damaged. On the other hand, when the thickness exceeds 2.5 times, as described above, not only the workability of assembling becomes extremely poor, but also the inorganic fibrous nonwoven fabric layer is broken.

[0011] The bulk density of the inorganic fibrous nonwoven fabric layer at the time of decompression sealing should be in the range 0.10 to 0.40 g / cm ^3. If the bulk density is too small, the restoring force of the inorganic fibrous nonwoven layer is weak, and the catalyst holder 4 dances due to the engine vibration or running vibration of the automobile, and the inorganic fibrous nonwoven layer is not only powdered or worn, but also This is because exhaust gas penetrates the inorganic fibrous nonwoven fabric layer.
Conversely, if the bulk density is too large, the inorganic fibrous nonwoven fabric itself will be crushed by the pressure during the pressure assembly in the subsequent step, or the catalyst holder will be damaged or deformed.

Next, the inorganic fibrous nonwoven fabric layer and the sealing material, the thicknesses of which are reduced by the airtight sheet, are wrapped around the catalyst support, and then the upper shell and the lower shell are applied. The shell is brought into close contact, and the outer periphery of the shell is clinched or fixed with bolts and nuts.

Next, as described above, the airtight sheet can be heated and incinerated after the manufacture of the exhaust gas purifying converter. Further, even when the exhaust gas purifying converter is mounted on a vehicle or the like, part or all of the airtight sheet may remain.

The inorganic fibrous nonwoven fabric is preferably made of a material selected from nonwoven fabrics of alumina fiber, silica-alumina fiber and silica fiber. These are all substances having excellent heat resistance. Further, in consideration of the material cost, the inorganic fibrous nonwoven fabric is provided with alumina fibers that are more expensive but more excellent in heat resistance on the side of the catalyst holder that becomes high in temperature,
Inexpensive but slightly inferior heat-resistant silica
A two-layer structure such as disposing alumina fibers can be adopted.

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

[0016]

In the exhaust gas purifying converter according to the production method of the present invention, an inorganic fibrous nonwoven fabric layer and a sealing material are provided as a sealing layer between the catalyst holder and the shell. The inorganic fibrous nonwoven fabric layer and the sealing material have excellent heat resistance. Therefore, even when the inorganic fibrous nonwoven fabric layer and the seal material are exposed to the exhaust gas, particularly the high-temperature lean burn exhaust gas, the seal failure does not occur unlike the conventional seal material. In particular, even if the metallic shell thermally expands in the outer peripheral direction, a sufficient exhaust gas sealing property is maintained by the sealing material.

In the production method of the present invention, the inorganic fibrous nonwoven fabric in the exhaust gas purifying converter is covered with an airtight sheet, and the inside of the airtight sheet is in a reduced pressure state. Therefore, the thickness of the inorganic fibrous nonwoven fabric is reduced, and the thickness becomes equal to or larger than the distance between the catalyst holder and the shell by 150%. Therefore, the inorganic fibrous non-woven fabric layer can be easily and reliably assembled between the shell and the catalyst holder without requiring a complicated process together with the sealing material, and after the converter for exhaust gas purification is assembled. The catalyst holder does not move or break in the shell during handling and transportation. In this way, the brittle inorganic fibrous nonwoven layer can be easily assembled in the shell without damaging it.

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

[0019]

【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 the present embodiment includes a catalyst holder 4, a shell 2 covering the outside of the catalyst holder 4, and an inorganic fibrous nonwoven fabric layer 31 disposed therebetween. The inorganic fibrous nonwoven fabric layer 31 and the seal material 932 are covered with a hermetic sheet 32. Then, the inorganic fibrous nonwoven fabric layer 31
Is a two-layer structure of alumina fiber on the catalyst holder 4 side and silica-alumina ceramic fiber on the shell side, the hermetic sheet 32 is polyethylene, and the seal layer 932
Is a thermally expandable sheet made of unexpanded vermiculite and ceramic fibers, and the catalyst holder 4 is made of cordierite. Reference numeral 39 denotes a seam formed when the inorganic fibrous nonwoven fabric layer 31 and the sealing material 932 are arranged. The shell 2 includes an upper shell 21 and a lower shell 22. Each of the upper shell 21 and the lower shell 22 is a half-oval shell. At both ends, bolt holes 21
1 are provided.
The catalyst holder 4 is a honeycomb body having a lattice cross section. The cross section is an ellipse whose size is 15 mm
0 mm and the minor axis is 100 mm. In the exhaust gas purification converter 1 of the present embodiment, the catalyst holder 4 and the shell 2
An inorganic fibrous sheet 31 is provided as a catalyst holding layer, and a thermal expansion sheet 32 is provided as a seal layer. Also,
The inorganic fibrous nonwoven fabric layer 31 and the thermal expansion sheet 32 are covered with an airtight sheet 32.

As a result, the inorganic fibrous nonwoven fabric layer 31 which is excellent in heat resistance but is brittle and weak in friction and the like can be assembled in the shell 2 without damaging the inorganic fibrous nonwoven fabric layer 31. Therefore, even if the inorganic fibrous nonwoven fabric layer 31 of the present example is exposed to the exhaust gas, particularly the high-temperature lean burn exhaust gas, the deformation and the quality due to the decrease in the expansion pressure like the conventional wire mesh cushioning material are obtained. Does not cause deterioration. Furthermore, the sealing property by the thermal expansion sheet is extremely good.

Next, a method of manufacturing the converter for purifying exhaust gas according to the present invention will be described. As shown in FIG. 2A, a plate-like inorganic fibrous nonwoven fabric 31 having a short side of 75 mm, a long side of 400 mm, a thickness of 25 mm, and a bulk density of 0.10 g / cm ³ , and a short side of 25 mm, a long side of 400 mm and a thickness of 5.7mm,
A plate-like thermal expansion sheet having a bulk density of 0.60 g / cm ³ is prepared. The inorganic fibrous nonwoven fabric 31 and the thermal expansion sheet are provided with a concave engaging portion 310 at an end portion and a convex engaging portion 311 meshed with the concave engaging portion 310. On the other hand, as shown in FIG.
Prepare Next, as shown in FIG. 2 (C), the inorganic fibrous nonwoven fabric layer 31 and the sealing material 932 are sandwiched between the heat-sealing films 32 from above and below, and the inside thereof is depressurized by a vacuum packing device. 31 and the film 32 around the sealing material 932 are stuck together by hot melt and completely sealed. Then, the excess portion of the film is cut. This reduces the thickness of the inorganic fibrous nonwoven fabric layer 31 as shown in FIG.
mm, it is a fiber sealing member 3 made of a bulk density of 0.25 g / cm ^3. Thereafter, the outer surface of the fiber seal 3 was coated with lubricating oil. Next, as shown in FIG. 3A, the catalyst holder 4 is placed on the fiber seal 3. Next, as shown in FIG. 3 (B), the fiber seal 3 is annularly coated around the catalyst holder 4. At this time, the concave engaging portions 310 and the convex engaging portions 311 at both ends of the inorganic fibrous nonwoven fabric layer 31 and the sealing material 932 are engaged 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 3 and pressurized. Then, 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 example, the inorganic fibrous nonwoven fabric layer 31 and the sealing material 932 can be easily attached between the shell 2 and the catalyst holder 4 without damaging the inorganic fibrous nonwoven fabric layer 31. Thus, the exhaust gas purification converter 1 can be easily manufactured. At this time, the catalyst holder 4 and the shell 2
Has a clearance of 6 mm.

[Brief description of the drawings]

FIG. 1 is a sectional perspective view of an exhaust gas purification 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 the first embodiment, following FIG. 2;

FIG. 4 is a longitudinal sectional view of a conventional converter for purifying exhaust gas.

FIG. 5 is an explanatory view relating to mounting of a conventional cushioning sealing material.

FIG. 6 is an explanatory view of a problem following the mounting of the cushioning seal material, following FIG. 5;

[Explanation of symbols]

 1: converter for purifying exhaust gas 2: shell 21: upper shell 22: lower shell 3: fiber seal body 31: ceramic fiber layer 32: airtight sheet 4: catalyst holder

Claims (2)

(57) [Claims] Attachment of a converter heat-insulating sealing material for a vehicle exhaust gas purification comprising a catalyst holding body, a shell covering the outside of the catalyst holding body, an inorganic fibrous nonwoven fabric layer and a sealing material disposed therebetween. In the method, a plate-shaped inorganic fibrous nonwoven fabric and a sealing material are simultaneously placed in an airtight sheet, and the inside is reduced in pressure to reduce the thickness. 40
g / cm ³ and a thickness of 1.0 to 2.5 times the clearance after assembling the catalyst holder and the shell, and then sealing the airtight sheet. A method for mounting a heat insulating sealing material for a converter for purifying exhaust gas for automobiles, wherein an inorganic fibrous nonwoven fabric layer and a sealing material are arranged between the catalyst holder and the shell and assembled under pressure. 2. The airtight sheet according to claim 1, wherein:
A method for mounting a heat insulating sealing material for a converter for purifying exhaust gas for automobiles, comprising an organic synthetic sheet made of polyvinyl chloride, polyethylene, ionomer resin or the like.