JPH09267044A - Metallic carrier for catalytic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a deformation of a honeycomb body and a cracking of a brazing part by relaxing a thermal stress generated at the honeycomb body of a metallic carrier for a catalytic device. SOLUTION: The metallic carrier 10 is composed of the honeycomb body 4 formed by lapping and winding a corrugated panel material 1 and a flat panel material 2 in a form like a roll and an outer cylinder 5 covering the honeycomb body. A brazing part region 3 of brazing material 3a and 3b joining the panel materials with each other and the honeycomb body 4 and the outer cylinder 5 is provided at a range from a central part of a shaft direction of the honeycomb body 4 to a gas outlet part 4b and a catalyst carrying region W is provided between a gas inlet part 4a and this side of the brazing part region 3, and the outer cylinder 5 is provided so that it covers from the central part of the shaft direction of the honeycomb body 4 to a downstream side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal carrier for a catalyst device forming a honeycomb body used in an exhaust gas purifying device for an internal combustion engine, and more particularly to a metal carrier for a catalyst device having a rolled honeycomb body.

[0002]

2. Description of the Related Art As shown in FIG. 3, a metal carrier for a catalyst device used in a conventional exhaust gas purifying apparatus is located between a thin metal flat plate member 32 and a corrugated plate member 31 over the entire axial length of the plate member. In X, the brazing material 33 is interposed, and the flat plate material 32
As shown in FIG. 3 (B), the corrugated sheet material 31 and the corrugated sheet material 31 are overlapped with each other to form a honeycomb body 34 by rolling it from the center to form a honeycomb body 34, and the brazing material 33 is melted by using a vacuum furnace. I was joining. A Ni-based brazing material was used as the brazing material, and a ferritic stainless steel material was used as the flat plate material and the corrugated plate material. A structure in which the honeycomb body 34 thus formed is accommodated in a metal outer cylinder 35 is known as a metal carrier 30 for a catalyst device (for example, JP-A-56-4373).

A catalyst supporting layer made of alumina or the like is formed over the entire surface of the honeycomb passage of the honeycomb body in the axial direction, and a noble metal catalyst is supported on the catalyst supporting layer and functions as an exhaust gas purifying catalyst. Then, it is arranged in the exhaust passage of the internal combustion engine to purify HC, CO, NO _x, etc. in the exhaust gas. Since it is necessary to secure as many honeycomb passage areas as possible in a limited volume, the thicknesses of the flat plate member and the corrugated plate member are as thin as possible within a range where the strength can be maintained.

[0004] In the above-mentioned conventional metal carrier for a catalytic device, the flow velocity of the exhaust gas passing through the honeycomb body increases as it goes from the outer layer to the inner layer of the honeycomb body. Due to heat generated by the catalytic reaction and heat dissipation from the outer cylinder, a temperature distribution is generated in which the temperature is higher in the inner layer and lower in the outer layer. Furthermore,
On the gas inlet side of the honeycomb body, the catalytic reaction particularly actively occurs due to the inflow of high-temperature exhaust gas, so that the rate of temperature rise and cooling applied to the brazing part is high, and the brazing part is likely to be subjected to thermal shock.

Therefore, the thermal stress generated in the plate material and the brazed portion of the plate material on the gas inlet side of the metal carrier is larger than that on the gas outlet side, and as shown in FIG. 4 (A), there are two or more brazing positions. When provided, there is no escape area for strain due to thermal stress, and as shown in FIG. 4 (B), deformation of the honeycomb body and breakage due to cracks in the brazed portion are likely to occur, and as shown in FIG. 5 (A). As described above, there is a drawback that the brazing material 33 and the brazing-affected zone 37 of the brazing portion are deteriorated due to oxidation due to high temperature and the strength thereof is weakened.

In order to eliminate these drawbacks, FIG.
As shown in (B), a honeycomb body having a so-called partial flat plate double structure in which two flat plate materials 32 are stacked in a range of two or more layers from the outside, and the two flat plates are simply stacked without joining. A metal carrier 40 including 34a is disclosed,
Further, there is also disclosed a metal carrier including a honeycomb body having a so-called all-layer flat plate double structure in which the flat plate material from the winding start to the winding end of the honeycomb body is doubled. In these two types of flat plate double-structured honeycomb bodies, neither brazing material is used to join the flat plate materials to each other, and the thermal stress generated by heating and cooling is caused by the sliding between the two flat plate materials. Absorbs and relaxes to prevent cracks in the brazed part.

Further, in order to eliminate the disadvantage that the strength of the brazed portion is deteriorated due to deterioration due to oxidation, as shown in FIG. 5B, the diffusion depth of the brazing material 33 into the base material 36, that is, the brazing-affected zone. A joining method for suppressing the depth of 37 to less than the plate thickness of the base material 36 has been developed.

[0008]

In the above-mentioned conventional honeycomb body having a double-layered flat plate structure, since the flat plate members having the double structure are not joined by the brazing material, the corrugated plate member and the flat plate member are not bonded to each other. Although it is possible to prevent the occurrence of cracks in the brazed portion between and, in the case of severe operating conditions accompanied by severe vibration, the two unbonded flat plate materials are displaced in the axial direction, as shown in Fig. 7. Such a so-called telescoping phenomenon occurs, and particularly when the axial length of the honeycomb body is short (for example, 30 mm or less) or the outside diameter of the honeycomb body is large, there is a drawback that the telescoping phenomenon is likely to occur. .

In order to eliminate this drawback, another honeycomb body in which plate materials are joined by a brazing material and does not carry a catalyst is arranged in series in contact with a honeycomb body having a flat plate double structure, in series with the honeycomb body of the former case. There is a method of suppressing the telescoping phenomenon that occurs in the honeycomb body, but there is a drawback that the manufacturing cost becomes high.

Further, in the above-mentioned processing method for suppressing the diffusion depth of the brazing material into the base material in order to prevent the strength of the brazing portion from being reduced by oxidation, the oxidation life of the brazing portion is extended. However, the effect is not sufficient, and the defect that the honeycomb body falls off has not been solved.

An object of the present invention is to provide a metal carrier capable of relaxing the thermal stress generated in the honeycomb body and preventing the deformation of the honeycomb body and the cracking of the brazing portion.

[0012]

MEANS FOR SOLVING THE PROBLEMS A metal carrier for a catalytic device according to the present invention is a flat plate composed of a corrugated sheet material in which a strip-shaped thin metal plate is bent to form continuous corrugation and a flat strip-shaped thin metal plate. The material, abutting on each other and overlapping, and joined by a brazing material, a honeycomb body having a large number of mesh-like passages formed by being wound in a roll shape, and an outer cylinder covering the outer surface of the honeycomb body. In the metal carrier for a catalyst device having, the brazing part region of the brazing material that joins the corrugated plate material and the flat plate material and the honeycomb body and the outer cylinder is provided in the range from the axial center part of the honeycomb body to the gas outlet part. Further, the range of the honeycomb body carrying the catalyst is provided in the range from the gas inlet part to the front of the brazing part region. In addition, the outer cylinder
The honeycomb body is covered from the central portion in the axial direction to the downstream side, and is joined to the honeycomb body by a brazing material in the brazing portion region of the honeycomb body.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a diagram of an embodiment of a metal carrier for a catalyst device of the present invention, FIG. 1 (A) is a longitudinal sectional view including a shaft, and FIG. FIG. 1C is a schematic vertical cross-sectional view showing the relationship between members, and FIG. 1C is a vertical cross-sectional view including a shaft according to another embodiment.

1A and 1B, the corrugated sheet material 1
Is a plate material in which a strip-shaped thin metal plate is bent to form continuous wavy irregularities, and the flat plate material 2 is a plate material formed from a flat strip-shaped thin metal plate. The brazing filler metals 3a and 3b are sandwiched between the plate members to be overlapped with each other, and the overlapped plate members are wound in a roll shape from one end in the longitudinal direction around the axis to form the honeycomb body 4.

The axial range of the brazing part region 3 formed by the brazing materials 3a and 3b is within the range from the axial center part of the honeycomb body 4 to the gas outlet part 4b. However, brazing is not performed within the range of 5 mm in the axial direction from the edge of the gas outlet portion 4b of the honeycomb body 4. This is to prevent the melting of the brazing material, especially the melted brazing material from flowing out from the end edge of the outlet portion 4b to the outside. The axial width of the brazing area 3 is
10 to 30% of the axial length of the honeycomb body 4 is suitable. In FIG. 1, each one brazing material 3a, 3b sandwiched between the flat plate material 2 and the corrugated plate material 1 is described, but the number is not necessarily limited to one.

The range W in which the honeycomb body 4 supports the catalyst is
The range from the gas inlet 4a of the honeycomb body 4 to 50 to 80% of the axial length of the honeycomb body 4 is set. However, 5 mm from the brazing area 3 so that the catalyst does not get on the brazing area.
Separate them.

The outer cylinder 5 is a cylindrical cylinder formed of a metal plate having a thickness of 1 to 3 mm, which covers the outer surface of the honeycomb body 4, and is brazed to the honeycomb body 4 in the brazing part region 3, and further the honeycomb is formed. It is fixed by welding to a muffler or the like (not shown) to hold the body 4.

In the metal carrier shown in FIGS. 1A and 1B described above, brazing in the brazing part region 3 having a narrow width is performed within the range from the axial center part of the honeycomb body 4 to the outlet part 4b. Further, since the axial width of the brazing part region 3 is as narrow as 10 to 30% of the axial length of the honeycomb body 4, the corrugated sheet material 1 forming the honeycomb body 4 upstream of the brazing part region 3 is performed. Since the expansion of the flat plate material 2 due to heat can be freely expanded toward the gas inlet side, stress due to thermal strain between the plate materials and between the honeycomb body 4 and the outer cylinder 5 is released.

Further, since the range W in which the catalyst is supported is set to the range from the gas inlet 4a of the honeycomb body 4 to the front of the brazing part region 3, heat generation due to the catalytic reaction occurs in the brazing part region 3. No, and therefore the temperature of the braze area 3 is kept lower than the other parts, thus preventing the braze from oxidizing.

FIG. 1C shows the outer cylinder 5 in FIG.
Is a schematic vertical sectional view of an embodiment in which the outer cylinder 5a is shortened to cover the downstream side from the central portion in the axial direction of the honeycomb body 4. In this case, the axial length of the outer cylinder 5a is the same as that of the honeycomb body 4.
10 to 60% of the honeycomb body 4 is covered from the end edge of the outlet portion 4b. When the outer cylinder 5a thus shortened is used to release the outer peripheral surface of the honeycomb body 4 on the gas inlet side from the pressing by the outer cylinder, the stress due to heat expansion / contraction of the honeycomb body 4 on the gas inlet side is further alleviated. Therefore, the stress of the brazed portion is also reduced, which has a favorable effect on the life of the honeycomb body 4.

FIG. 2 is a schematic vertical cross-sectional view showing another embodiment of the metal carrier of the present invention.
The brazing part region 3 is provided in the central part in the axial direction of the honeycomb body 4
_The catalyst supporting ranges W ₁ and W ₂ are provided on the upstream side and the downstream side of the brazing part region 3 of FIG. ₁ , and FIG. 2 (A) shows the outer cylinder 5 over the entire length of the honeycomb body 4 _1. 2B is a view in which the outer cylinder 5b is arranged only in the central portion in the axial direction of the honeycomb body 4 ₁ .

As shown in FIG. 2A, the metal carrier 11
In the honeycomb body 4 ₁ of the above, in the brazed portion region 3 at the central portion in the axial direction, the corrugated plate material and the flat plate material and the honeycomb body 4 ₁ and the outer cylinder 5 are joined by the brazing materials 3 a and 3 b. But,
Since the brazing material is not applied to the other portions, both plate materials can freely extend from the axial central portion toward both end portions. Therefore, most of the plate members of the honeycomb body 4 ₁ excluding the brazing part region 3 and between the honeycomb body 4 ₁ and the outer cylinder 5
The thermal stress acting between and is greatly reduced. Not yet supported catalyst in the brazed area 3, since the catalyst is supported on both sides of the honeycomb body 4 ₁ except brazing region 3, the brazed area 3 receives the heat generated by the catalytic reaction directly Therefore, the temperature is maintained at a lower temperature than that of the catalyst supporting portion, and it is possible to prevent a decrease in life due to oxidation of the brazing portion.

FIG. 2B shows a case where the outer casing 5 of the metal carrier 11 shown in FIG. 2A is limited to the brazing part region 3 at the central portion in the axial direction to form the metal carrier 12. Since the honeycomb body 4 ₁ can freely expand not only in the axial direction but also in the radial direction in the portion where the outer cylinder 5b is not provided, the thermal stress acting on the plate material is further reduced as compared with the case of FIG. 2A. be able to.

In the metal carriers 11 and 12 shown in FIG. 2, the catalyst can be separately supported on the upstream side and the downstream side of the gas flow with respect to the honeycomb body 4 _1. Therefore, when a two-way catalyst is used. It is convenient.

[0025]

As described above, the present invention provides a metal carrier including a honeycomb body formed by stacking a corrugated sheet material and a flat sheet material and winding the corrugated sheet material in a roll shape, and an outer cylinder covering the honeycomb body. The brazing part region of the brazing material that joins the honeycomb body and the outer cylinder is provided within the range from the central part of the honeycomb body to the gas outlet part, and the catalyst carrying range is further defined from the gas inlet part to the brazing part region. By setting the distance to this side, the honeycomb body can be easily expanded in the axial direction, stress is not generated between the plate materials, and the brazing area is not affected by the heat generation due to the catalytic reaction, so the temperature is kept low. It has the effect of improving the durability of the sagging and honeycomb body, and further, the length of the outer cylinder,
If it is provided so as to cover the downstream side from the central portion in the axial direction of the honeycomb body, since the expansion of the honeycomb body in the radial direction is not hindered, it is possible to reduce the thermal stress applied to the honeycomb body on the upstream side. This has the effect of further improving durability.

[Brief description of drawings]

FIG. 1 is a view showing a vertical cross section of a metal carrier for a catalyst device according to the present invention, FIG. 1 (A) is a schematic vertical cross sectional view including a shaft, and FIG. 1 (B) is a view constituting each of FIG. 1 (A). FIG. 1C is a schematic vertical cross-sectional view showing the relationship of members, and FIG. 1C is a schematic vertical cross-sectional view including the axis of another metal carrier.

FIG. 2 is a schematic vertical cross-sectional view of another metal carrier for a catalyst device of the present invention.

FIG. 3 is a view of a metal carrier for a catalyst device according to a conventional technique, FIG. 3 (A) is a schematic sectional schematic view perpendicular to an axis showing a configuration of a plate material, and FIG. 3 (B) is an external view of the metal carrier. Perspective view,
FIG. 3C is a diagram showing a range X in which the brazing material is interposed.

FIG. 4 is a schematic view of a longitudinal section including a shaft of a honeycomb body according to a conventional technique, FIG. 4 (A) shows a brazing position, and FIG. 4 (B) shows deformation and breakage of a plate material. It is a figure which shows a state.

FIG. 5 is a schematic view showing a cross section of a brazing part of a plate material according to a conventional technique, and FIG.
FIG. 5B is a diagram of a joining method in which the diffusion depth of the brazing material is limited.

6A and 6B are views of a honeycomb body having a flat plate double structure according to a conventional technique, FIG. 6A is a schematic sectional view showing the structure of a plate material, and FIG. 6B is a perspective view of the appearance of a metal carrier. It is a figure.

FIG. 7 is a schematic perspective view of the appearance showing the telescoping of the honeycomb body.

[Explanation of symbols]

1,31-wave plate 2, 32 flat plate 3 brazing region 3a, 3b, 33 brazing material 4, 4 _1, 34, 34a honeycomb body 4a gas inlet 4b gas outlet 5, 5a, 5b, 35 outer cylinder 10 , 11, 12, 30, 40 Metal carrier 36 Base material 37 Brazing-affected zone W, W ₁ , W ₂ Catalyst carrying range X Range where brazing filler metal intervenes

Claims (2)

[Claims] 1. A brazing material in which a corrugated sheet material in which a strip-shaped thin metal plate is bent to form continuous corrugation and a flat sheet material made of a flat strip-shaped thin metal plate are in contact with each other and overlap each other. In a metal carrier for a catalyst device, comprising: a honeycomb body having a large number of mesh-shaped passages formed by being wound in a roll shape and joined together by an outer cylinder covering the outer surface of the honeycomb body, wherein the corrugated sheet material and the flat plate The brazing material region of the brazing material that joins the material and the honeycomb body to the outer cylinder is in the range from the axial center part of the honeycomb body to the gas outlet part, and the range of carrying the catalyst of the honeycomb body is A metal carrier for a catalyst device, which is located between the gas inlet portion and the front of the brazing portion area. 2. The outer cylinder covers the downstream side of the honeycomb body from the central portion in the axial direction, and is joined to the honeycomb body by a brazing material in the brazing part region of the honeycomb body. Metal carrier for catalytic converters.