JPH1176837A - Exhaust gas purification catalytic converter and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a catalytic converter for purifying exhaust gas, which can be assembled without damaging a catalyst holder, can reliably seal exhaust gas, and is excellent in productivity. I do. SOLUTION: A cylindrical metal shell made of stainless steel having a C-shaped or U-shaped cross section, and an outermost layer of an inorganic sheet made of alumina or silica-based ceramic fiber covered with an organic resin sheet. After fitting the sheet, the packing density of the synthetic sheet is 0.20-0.50 g / cm
Exhaust gas purifying catalytic converter assembled by tightening so that it becomes ³ and the cross-section becomes O-shaped, and then welded and assembled.

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 of an automobile and a method for manufacturing the same, and more particularly, to a structure for assembling a metal shell mounted on the outside of a catalyst holder and a seal layer interposed therebetween and a method therefor. This is a proposal having the following features.

[0002]

2. Description of the Related Art Exhaust gas purifying catalytic converters mounted on vehicles are mainly classified into a clamshell type shown in FIG. 1 and a press-fit type (exhaust manifold integrated type) shown in FIG. The former is composed of a catalyst support 4, metal shells 21 and 22 in a half-split state to cover the outside thereof, and a seal layer composed of an inorganic sheet 3 and a metal net 5 interposed therebetween. On the other hand, in the latter case, a seal layer composed of the inorganic sheet 3 and the metal net 5 is previously wound around the outside of the catalyst holder 4 and then pressed into the cast iron shell 23.

Generally, the inorganic sheet 3 is formed by molding a mixture of silica, alumina-based ceramic fiber, unexpanded vermiculite, an inorganic binder and an organic elastic substance into a sheet. This is a seal layer used to prevent exhaust gas from leaking from between the catalyst holder 4 and the catalyst holder 4.

Incidentally, in recent years, as a catalytic converter shape other than the shapes shown in FIGS.
No. 10 and Japanese Patent Application Laid-Open No. 8-42333 propose a press-fit type (Assy structure) using a metal pipe having a predetermined thickness without dividing a metal shell into two parts. However, in these known techniques, after press-fitting a seal layer made of a catalyst support and an inorganic sheet into a metal pipe, a rib is formed on the metal pipe as a countermeasure against “shift” of the catalyst support, or a swaging process or the like is performed. The secondary processing must be performed, and the problem of low productivity remains.

Other proposals for improvement include, for example,
No. 58-7806 proposes a method in which a rolled rectangular plate is directly wound around the outer periphery of a catalyst support around which an inorganic sheet is wound. However, in this conventional technique, when winding a rectangular plate, in order to prevent the inorganic sheet from being sandwiched, one end of the rectangular plate is pressed and pre-processed so that the plates overlap each other in the wound state. doing. For this reason, this method has a problem that not only the material loss occurs due to the overlap margin but the cost is increased, but also the packing density of the inorganic sheet located in the pressed portion is reduced.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to propose a structure of a catalytic converter which can overcome the above-mentioned problems of the prior art. Another object of the present invention is to provide a method of manufacturing a catalytic converter for purifying an exhaust gas which can be easily assembled without damaging a catalyst holder, can reliably seal exhaust gas, and is excellent in productivity. Is to propose.

[0007]

As a result of diligent studies aimed at realizing the above-mentioned object, the inventors have found that the sealing material interposed between the catalyst holder and the metal shell and the assembling process of the metal shell have been carried out. We thought that it was necessary to devise it, and arrived at the present invention according to the following gist configuration. That is, the present invention provides a catalytic converter comprising a columnar catalyst support, a cylindrical metal shell 2 placed on the outside of the catalyst support, and a seal layer S interposed therebetween. A synthetic sheet 6 in which an outermost layer of an inorganic sheet made of alumina-based or silica-based ceramic fiber is covered with an organic resin sheet 7 in a cylindrical metal shell material 2 'made of stainless steel having a C-shaped or U-shaped cross section. After fitting, the cylindrical metal shell material 2 'is tightened so that the packing density of the synthetic sheet is 0.20 to 0.50 g / cm ³ and has an O-shaped cross section, and then is welded and interposed. An exhaust gas purifying catalytic converter characterized by being sandwiched.

The above-mentioned catalytic converter according to the present invention is an exhaust gas purifying catalyst comprising a columnar catalyst holder, a cylindrical metal shell covering the outside of the catalyst holder, and a seal layer interposed therebetween. In manufacturing the converter, a stainless steel sheet serving as a metal shell is formed into a C-shaped or U-shaped cross section, and a sealing layer mainly composed of an inorganic sheet is provided on the outer periphery in the cylindrical metal shell material. Then, the cylindrical metal shell material is tightened, then the cylindrical metal shell material is formed into a cylindrical shape, and at the same time the seal layer is pressed and compressed, and then the side edges of the cylindrical metal shell are welded together, Thereafter, a method for manufacturing a catalytic converter for purifying exhaust gas is proposed, wherein the cylindrical metal shell is subjected to contraction or expansion according to the diameter of an exhaust pipe to be connected.

In the present invention, it is preferable that the seal layer is formed of a synthetic sheet in which an outer surface of an inorganic sheet is coated with an organic resin. The seal layer is formed of an organic resin-coated inorganic sheet obtained by molding an inorganic fiber of at least one of alumina, silica, alumina-silica and glass into a mat shape, and coating the outer surface thereof with an organic resin sheet. Is preferred. The packing density of the seal layer sandwiched between the metal shell and the catalyst holder was set to 0.20.
It is preferable that the metal shell is pressed in the circumferential direction so as to be within a range of 0.50 g / cm ³ and tightened.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The feature of the present invention is that a ceramic layer (alumina-based, silica-based) and an inorganic mixed fiber (alumina-silica, glass) are molded into a mat shape and then replaced with a metal net. Using a synthetic sheet bound and fixed with an organic resin sheet, and in a state of being interposed and sandwiched between the catalyst holder and the metal shell, the packing density of the synthetic sheet is 0.20 to 0.50 g / c.
The object is to press the metal shell material formed into a C-shaped cross section in the circumferential direction and tighten the metal shell material in the radial direction so as to obtain m ³ .

In the present invention, the reason why the packing density of the organic resin-coated inorganic sheet sandwiched between the catalyst support and the metal shell, that is, the sealing layer made of a synthetic sheet, is 0.20 g / cm ³ or more is more than that. If the particle size is small, a predetermined holding force cannot be obtained in the metal shell, and the catalyst holding member may be displaced. If the particle size is larger than 0.50 g / cm ³ , the inorganic fiber may be broken and scattered.

As described above, one of the features of the present invention resides in that, as the material of the sealing layer, an organic resin sheet is used instead of the conventional metal net 5 to bind and fix ceramic fibers as a matrix. That is, it is preferable to form a synthetic sheet in which an organic resin sheet such as pulp paper, silicone resin, polyvinyl chloride, or polyethylene is coated on the outer surface of an inorganic sheet formed by molding ceramic fibers into a mat shape. .

Another reason for coating the outer surface of the inorganic sheet with the organic resin sheet is to smoothly accommodate the catalyst holder in a cylindrical metal shell. Therefore, in the present invention, it is preferable to use the organic resin sheet having good surface lubricity. As an example of such an organic resin sheet, a material having a low surface friction coefficient is preferably used, and for example, polyvinyl chloride and polyethylene are particularly preferable.

Another feature of the present invention is how well the catalyst support coated with a sealing layer, ie, a synthetic sheet composed of an organic resin-coated inorganic sheet, fits and fits in a metal shell. . For this purpose, in the present invention, a metal shell material, that is, a stainless steel
It is processed into a shape (hereinafter simply referred to as "C type") to form a cylindrical metal shell material, which is further processed into an O shape, that is, a cylindrical shape, and then butted and welded to each other to form a cylindrical shape. Is to do. In particular, in this processing step, the catalyst holder is fitted in a cylindrical metal shell material at the stage when a stainless steel plate is processed into a C shape,
It is characterized in that the cylindrical metal shell material is pressurized so as to be tightened in a circumferential direction so as to have a predetermined diameter, and is processed into an O-shape into a cylindrical shape.

Under such a sequential processing method, when the catalyst holder is fitted in the cylindrical metal shell, the outer diameter of the entire seal layer, that is, the entire outer diameter of the catalyst holder with the synthetic sheet, is reduced. Even if it is larger than the final diameter of the metal shell, it can be easily fitted. And because of this,
When the cylindrical metal shell having a C-shaped cross section to be subsequently formed is further processed into an O-shape and closed, the packing density of the seal layer can be freely controlled by the degree of tightening. That is, the packing density of the seal layer can be controlled.

After the cylindrical metal shell material having a C-shaped cross section is finally processed into an O-shape, when the two side edges are further welded and joined, the welding heat causes the above-mentioned synthetic sheet of the welded portion, especially the outermost layer. Since the organic resin sheet dissolves, the vacuum state of the seal layer is released, so that the holding force of the seal layer can be secured. Therefore, after welding, no deviation occurs even if an external force is applied to the catalyst holder.

At the end of the processing step, both ends of the metal shell formed into a cylindrical shape and welded are connected to the front and rear exhaust pipes. Weld the cone to make the finished product.

[0018]

【Example】

Embodiment 1 Hereinafter, an example of an exhaust gas purifying converter according to an embodiment of the present invention will be described with reference to FIG. As shown,
The converter 1 for purifying exhaust gas manufactured according to the method of the present invention has a sealing layer S in a clearance between a catalyst holder 4 made of cordierite having a honeycomb structure in cross section and a metal shell 2 covering the outer peripheral surface of the catalyst holder 4. Consisting of

Material 2 'for metal shell 2 used in the present invention
As shown in FIG. 4, is a stainless steel sheet having a C-shaped cross section. A synthetic sheet 6 mainly composed of the inorganic sheet 3 is wound around the inside of the C-shaped stainless steel sheet in advance. The placed catalyst holding body 4 is fitted in a predetermined position, and then the above-mentioned C-shaped cylindrical stainless steel sheet (metal shell material 2 ′) is turned into a cylindrical metal shell 2 having a predetermined diameter. After the tightening process, the side edges (joining portions) of the metal shell 2 are welded together,
The catalyst holder 4 and the inorganic sheet 3 are inserted and sealed inside. After that, the weld bead is removed, and both ends in the longitudinal direction of the metal shell 2 are processed to be contracted or expanded according to the diameter of an exhaust pipe to be connected, or a cone (part) is welded and attached.

The catalytic converter 1 for purifying exhaust gas obtained in this manner has a catalyst holder 4 and a synthetic catalyst inside a cylindrical metal shell material 2 'formed by forming a stainless steel plate into a C-shaped or U-shaped cross section. After the sealing layer S made of the sheet 6 is fitted, the joint is welded, so that it is possible to apply a compressive stress to the synthetic sheet 6, and the sealing layer S
Can be arbitrarily set within the range of 0.20 to 0.50 g / cm ³ .

Here, the catalyst produced as described above
Converter 1 (filling density: 0.20g / cm ^ThreeA) Temperature condition: 90
As a result of conducting a 300Hr vibration test at 0 ° C,
Yes, as a result, the catalyst holder 4 moves from the set position at all
Without this, the catalyst holder 4 itself may be damaged, such as chipping or cracking.
It was good without. This is because the skeleton of the seal layer S
High heat-resistant ceramic such as alumina fiber as machine sheet 3
Use a mat-shaped molded product consisting of only fiber
Therefore, even when exposed to high-temperature exhaust gas,
As in the case of a heat-expandable sealing material containing
This is because the quality does not deteriorate due to the deterioration.

Example 2 An exhaust gas purifying catalytic converter manufactured under the same materials and under the same manufacturing conditions as in Example 1 was manufactured by changing only the packing density of the sealing layer S made of a synthetic sheet to 0.50 g / cm ³ . Here, a vibration test similar to that of the first embodiment was performed on the catalytic converter 1 manufactured in this example. As a result, the catalyst holder 4 did not move from the set position, and the catalyst holder itself suffered damage such as chipping or cracking. It was good without anything.

[0023]

As described above, in the exhaust gas purifying catalytic converter according to the present invention, the catalyst holding body having the seal layer is housed in the cylindrical metal shell material formed of stainless steel into a C-shaped cross section. After fitting, it was tightened to a predetermined diameter, so the sealing layer was compressed in the radial direction, so the packing density was 0.20 to 0.50 g / cm ³
Can be freely set within the range. In addition, this allows the catalyst holder to be firmly sandwiched in the metal shell without causing damage. Further, according to the present invention, since the outermost layer of the sealing layer is covered with the organic resin sheet, a part of the organic resin sheet is melted when welding the side edge of the molded metal shell, and the sealing layer is sealed. Effectively works to prevent layer displacement. Further, in the present invention, unlike the conventional press-fit type, when the sealing layer is mounted in the metal shell, no shearing force is applied to the sealing layer, so that no damage occurs and a good sealing for a long period of time. Those having properties and holding properties are obtained. Further, in the present invention, the seal layer uses only inorganic fibers of alumina or silica, so that the exhaust gas does not deteriorate due to heat unlike the conventional method using a mixture of an expandable sealing material. Furthermore, the production method according to the present invention can produce a catalytic converter for purifying exhaust gas having excellent productivity, high heat resistance and high durability at low cost.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a conventional clamshell type exhaust gas purifying catalytic converter.

FIG. 2 is an exploded perspective view of a conventional exhaust manifold integrated catalytic converter for exhaust gas purification.

FIG. 3 is an exploded perspective view showing a part of the exhaust gas purifying catalytic converter according to the present invention in a cutaway manner.

FIG. 4 is an explanatory view showing a metal shell forming step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust gas purification catalytic converter 2 Metal shell 2 'Tubular metal shell material 3 Inorganic sheet 4 Catalyst holder 5 Metal net 6 Synthetic sheet 7 Organic resin sheet S Seal layer 21 Metal shell 22 Metal shell 23 Cast iron shell

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI F01N 3/28 311 F01N 3/28 311S 311U B01D 53/36 B (72) Inventor Takumi Okada 1st Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd.

Claims (5)

[Claims] 1. A catalytic converter comprising a columnar catalyst support, a cylindrical metal shell covering the outside of the catalyst support, and a seal layer interposed therebetween, wherein the seal layer has a C-shaped cross section. Or, after fitting a synthetic sheet obtained by coating an outermost layer of an inorganic sheet made of alumina-based or silica-based ceramic fibers with an organic resin sheet in a cylindrical metal shell material made of U-shaped stainless steel, The synthetic metal sheet is clamped so that the packing density of the synthetic sheet is 0.20 to 0.50 g / cm ³ and has an O-shaped cross section, and is then joined by welding and clamping. Exhaust gas purification catalytic converter. 2. A method for manufacturing an exhaust gas purifying catalytic converter comprising a columnar catalyst support, a cylindrical metal shell covering the outside of the catalyst support, and a seal layer interposed therebetween, is used as a metal shell. A stainless steel plate is formed into a C-shaped or U-shaped cross-section cylindrical shape, and a catalyst holder having a seal layer mainly composed of an inorganic sheet is fitted around the outer periphery of the cylindrical metal shell material. After the cylindrical metal shell material is tightened and formed into a cylindrical shape, and simultaneously the seal layer is pressurized and compressed, the side edges of the cylindrical metal shell are welded together, and then the cylindrical metal shell is connected. A method for producing a catalytic converter for purifying exhaust gas, comprising reducing or expanding a pipe according to the diameter of an exhaust pipe to be exhausted. 3. The method according to claim 2, wherein the seal layer is formed of a synthetic sheet in which an organic resin is coated on an outer surface of an inorganic sheet. 4. The organic resin-coated inorganic sheet in which the seal layer is formed by molding at least one kind of inorganic fiber of alumina, silica, alumina-silica and glass into a mat shape, and coating an outer surface thereof with an organic resin sheet. 4. A composite sheet comprising:
The production method described in 1. 5. The tightening force of the metal shell is adjusted so that the packing density of the seal layer sandwiched between the metal shell and the catalyst support falls within the range of 0.20 to 0.50 g / cm ^3. The method according to claim 2, 3, or 4.