JPH08141409A - Metallic carrier for catalytic device - Google Patents

Abstract

PURPOSE: To obtain a metallic carrier causing no metal touch between two superposed flat sheets, capable of easy sliding, relieving thermal stress and having improved durability as a metallic carrier having a double flat sheet structure so as to relieve thermal stress produced in the roll-shaped honeycomb body. CONSTITUTION: A corrugated sheet 1, a flat sheet 22 , a 2nd corrugated sheet 31 and a flat sheet 21 are superposed and wound to form a roll-shaped honeycomb body 11. The flat sheet 21 has the same length as the corrugated sheet 1 and the flat sheet 22 is shorter than the flat sheet 21 and has such a length as to form the outer two layers of the honeycomb body 11. The 2nd corrugated sheet 31 is interposed between the flat sheets 21 , 22 without joining and has the same length as the flat sheet 22 . When a coating film of aluminum oxide is formed on the surface of the 2nd corrugated sheet 31 , a metal touch between the flat sheets can be prevented. The length and position of the flat sheet 22 or the 2nd corrugated sheet 31 are variable.

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 catalytic device forming a honeycomb body used in an exhaust gas purifying apparatus of an internal combustion engine, and more particularly to a catalyst in consideration of prevention of breakage and dropping of the rolled honeycomb body due to thermal stress. The present invention relates to a metal carrier for a device.

[0002]

2. Description of the Related Art As shown in FIG. 8A, a metal carrier for a catalyst device used in a conventional exhaust gas purifying apparatus has a brazing material 33 interposed between a thin metal flat plate material 31 and a corrugated plate material 32. Then, the flat plate member 31 and the corrugated plate member 32 are overlapped with each other, as shown in FIG.
As shown in (1), the honeycomb body 34 was formed by rolling it up from the center, the brazing filler metal 33 was melted using a high vacuum furnace, and the joining was performed at the contact portion of the plate materials. 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. The honeycomb body 34 thus formed is housed in a metal outer cylinder 35 and is known as a metal carrier 30 for a catalyst device (for example, Japanese Patent Laid-Open No. 56-4373).

A catalyst supporting layer made of alumina or the like is formed on the surface of the honeycomb passages of the honeycomb body, and the precious 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 much honeycomb passage area as possible in a limited volume, the thickness of the flat plate material and the corrugated plate material is as thin as possible within the range in which the strength can be maintained.

In the above-mentioned conventional metal carrier for a catalyst device, the flow velocity of the exhaust gas passing through the honeycomb body is higher from the outer layer portion to the inner layer portion of the honeycomb body, so that the honeycomb body comes into contact with the hot exhaust gas, Due to the heat generated by the catalytic reaction and the heat dissipation from the outer cylinder, a temperature distribution is generated in which the inner layer portion has a higher temperature and the outer layer portion has a lower temperature. Due to this temperature distribution, the expansion / contraction amount of the inner layer portion of the high temperature honeycomb body becomes larger than the expansion / contraction amount of the outer layer portion of the low temperature, so that thermal stress is generated between the inner layer portion and the outer layer portion. . This thermal stress is repeated each time the honeycomb body expands / contracts, but as shown in FIG. 8A, all flat plate materials 31 and corrugated plate materials 32 are integrally brazed through the brazing material 33. Therefore, there is a drawback that the thermal stress cannot be released and the joint portion between the flat plate member 31 and the corrugated plate member 32 is broken by long-term use.

In order to eliminate this drawback, FIG.
As shown in (B), two flat plate materials 31 are stacked in a range of two or more layers from the outside, and a metal carrier 4 including a honeycomb body 34a that is simply stacked without being bonded between the two flat plates.
0 is disclosed.

[0006]

The above-described conventional metal carrier for a catalyst device shown in FIG. 9 has two flat plate materials 31 stacked between at least two layers from the outer side of the roll-shaped honeycomb body. When the thermal stress acting on the honeycomb body 34a acts in the radial direction, the flat plate material 31 is first deformed and the thermal stress is circular as shown in FIG. In the case of working in the circumferential direction, as shown in FIG. 11, slippage occurs between the two flat plate members 31 and the stress is relieved. In order to perform these stress relaxations, it is necessary that the two flat plate members 31 can move freely with each other, but in reality, the two flat plate members 31 are in close contact with each other. Therefore, due to the heating when brazing the honeycomb body 34a, a metal touch is generated between the two flat plate members 31 due to solid-phase diffusion, and the flat plate members 31 are fixed to some extent. Since it is large, resistance to mutual movement is large, and free movement is restricted, so that the corrugated plate material 32 and the flat plate material 31 may be broken.

As a countermeasure against this, the above metal touch can be prevented by using at least one of the two flat plates having an oxide film formed on its surface in advance. The metal plate used is Fe-
Since it is a foil material of 20Cr-5Al, this oxide film becomes aluminum oxide (Al ₂ O ₃ ) and is very stable. Therefore, there is a drawback in that the coating film is not broken during brazing of the plate material, and therefore the surface requiring brazing cannot be brazed.

There is also a method of forming an oxide film by firing in the air after forming the honeycomb body 34a, but in this case, forming a film uniformly between the two flat plate members 31 stacked is as follows. This is difficult because the plates are in close contact with each other.

Further, it has been attempted to prevent metal touch by controlling the temperature during brazing to a low level to prevent the brazing material from diffusing into the plate material, but it is not possible to prevent it completely. There is.

An object of the present invention is to provide a metal carrier having a flat plate double structure for relieving thermal stress generated in a honeycomb body, without causing a metal touch between two flat plate materials and easily sliding. Therefore, it is an object of the present invention to provide a metal carrier for a catalytic device in which stress is relieved and which is durable.

[0011]

MEANS FOR SOLVING THE PROBLEMS A metal carrier for a catalytic device according to the present invention comprises a corrugated sheet material in which a strip-shaped thin metal plate is bent to form continuous corrugated irregularities, and a flat strip-shaped thin metal sheet. A flat plate material is formed into a honeycomb body having a large number of layered mesh-like air passages that are abutted against each other and overlapped with each other, and two flat plate materials are overlapped in at least two layers from the outside. And a corrugated metal sheet formed without being joined to each other, the thin corrugated metal sheet is bent to form a continuous corrugated corrugated sheet material. Are arranged without being joined between two flat plate members of at least one layer of the honeycomb body.

The metal plate forming the second corrugated plate material of the metal carrier for the catalytic device has an aluminum oxide coating layer on the surface in advance, or after the metal plate is formed into a corrugated shape, it is oxidized on the surface. It is preferable to have an aluminum coating layer.

Further, when the axial length of the metal carrier for the catalyst device is short, the surface on one side of the second corrugated plate member is 2
It is preferably joined to one of the stacked flat plate members.

[0014]

Since the second corrugated sheet material is arranged without being joined between the two flat plate materials of the honeycomb body having the flat double layer structure, the metal is provided between the two flat plate materials. Since the flat plate material that causes the touch can be freely deformed or slid in the radial direction, the stress of the honeycomb body is relieved.

By applying an aluminum oxide coating on the surface of the second corrugated sheet material, the metal touch between the second corrugated sheet material and the flat sheet material is removed, and the deformation and slippage are further facilitated.

When the axial length of the honeycomb body is short,
By joining one surface of the second corrugated sheet material to the flat sheet material, the telescoping phenomenon of the honeycomb body can be prevented.

[0017]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of a metal carrier for a catalyst device of the present invention, FIG. 1 (A) is a schematic partial cross-sectional view showing the configuration of a plate material, and FIG. 1 (B) is a roll of the plate material of FIG. 1 (A). Fig. 3 is a schematic view of a cross section of a honeycomb body formed by winding the honeycomb body.

In FIG. 1A, a corrugated sheet material 1 is a sheet material in which a strip-shaped thin metal plate is bent to form continuous corrugated irregularities, and flat plate materials 2 ₁ and 2 ₂ are flat strip-shaped thin metal sheets. The plate member 2 ₁ is a plate member and has the same length as the corrugated plate member ₁ . Flat plate 2 ₂ is shorter than the flat plate 2 _1, when forming a honeycomb body 11 wound into a roll overlaid with a wave plate 1 and the flat plate 2 _1, forming a range of from the outside of the honeycomb body 11 to second layer It has a length that can be.

The second corrugated sheet material 3 ₁ is a sheet material in which a strip-shaped thin metal plate is bent to form continuous corrugated irregularities. These two corrugated sheet materials are provided between the flat sheet material 2 ₁ and the flat sheet material 2 _2. It is arranged without being joined to the flat plate material of No. 1, and its length is such that when the honeycomb body 11 is formed by being rolled together with these plate materials, a range of two layers outside the honeycomb body 11 can be formed. Have

2 to 5 are schematic views of various embodiments of the metal carrier for a catalyst device of the present invention, (A) of each figure is a schematic cross-sectional schematic view showing the structure of a plate material, and each drawing. (B) is a schematic view of a cross section perpendicular to the axis of the honeycomb body formed by winding the plate material of (A) in each figure in a roll shape.

[0021] In FIG. 2 (A), when the flat plate 2 ₁ and a second wave plate 3 1,2 sheets wave plate is a both identical length, wound them into a roll, Figure 2 As shown in (B), it is possible to obtain the honeycomb body 12 which is a double-layered flat plate material and in which the second corrugated plate material 3 is arranged in all layers.

In FIG. 3A, the corrugated sheet material 1 and the two flat sheet materials 2 ₁ have the same length, and the second corrugated sheet material 3 having the same length as the plate material of the outermost layer between them. ₂ is provided, when the wound them into a roll, as shown in FIG. 3 (B), the honeycomb body 13 in which the second wave plate 3 ₂ is arranged only on one layer of the outermost periphery to obtain To be Usually, the thermal stress generated in the honeycomb body acts most on the outermost layer, and this form is effective for stress relaxation.

In FIG. 4 (A), the corrugated plate material 1 and the two flat plate materials 2 ₁ have the same length, and the second layer of plate material is provided between them in the position of the second layer from the outside of the honeycomb body. When the second corrugated sheet material 3 ₃ having the same length is arranged and wound in a roll shape, as shown in FIG. 4B, the second corrugated sheet material 3 3 is provided.
A honeycomb body 14 in which ₃ is arranged only in the second layer from the outside is obtained. Depending on the metal carrier, thermal stress may concentrate in the second layer from the outer periphery of the honeycomb body, and in this case, this form is effective for stress relaxation.

In FIG. 5 (A), the corrugated plate material 1 and the two flat plate materials 2 ₁ have the same length, and the central one layer is formed between them in the position of the central layer forming the central part of the honeycomb body. second wave plate 3 ₄ is provided with a plate member of the same length, when wound them into a roll, as shown in FIG. 5 (B), the second
A honeycomb body 15 in which the corrugated sheet material 3 ₄ is disposed in only one layer in the central portion is obtained. This type is effective for relaxing the thermal stress when the thermal stress is large at the center of the honeycomb body.

In the above-mentioned embodiment, the double structure of the flat plate material is provided in the range of two layers from the outside of the honeycomb body (FIG. 1) or in all layers of the honeycomb body (FIGS. 2 to 5). The double structure of the flat plate material may be provided in any number of layers from the outside of the honeycomb body to three or more layers.

Further, in the above-mentioned embodiment, the second corrugated sheet material is composed of two layers from the outer periphery of the honeycomb body (FIG. 1), all layers of the honeycomb body (FIG. 2), and only one outermost layer (FIG. 3). ) Only the second layer (FIG. 4) or the first layer (FIG. 5) of the central layer is provided, but the second corrugated sheet material is not limited to the above-mentioned arrangement position, and the outermost periphery of the honeycomb body 2 of any layer up to the center
Of course, it can be arranged between the flat plate members.

Second corrugated sheet material 3, 3₁ , 3₂ , 3₃ , 3_Four 
Are both flat plate materials 2₁ , 2 ₂ , Or 2₁ , 2
₁ Is not joined with. Also, these flat plate members
Not joined to.

FIG. 6 shows that the second corrugated plate member 3 is a flat plate member 2 having two sheets.
FIG. 3 is an explanatory diagram when a thermal stress in a radial direction acts on the honeycomb body inserted between the two.

In FIG. 6, when a radial force R acts on the corrugated sheet material 1 due to thermal stress, the corrugated sheet material 1 receives tension R in the radial direction and pulls the flat plate material 2 in the radial direction. Since the contact area between the flat plate member 2 and the second corrugated plate member 3 is extremely small, the amount of metal touch generated between the flat plate member 2 and the second corrugated plate member 3 is also very small. It can be transformed. The thermal stress in the radial direction is absorbed by this deformation.

FIG. 7 is an explanatory view when a thermal stress in the circumferential direction acts on the same honeycomb body as that shown in FIG.

In FIG. 7, the contact area between the second corrugated plate member 3 and the two flat plate members 2 is very small, and therefore the amount of metal touch generated between them is very small, so that the frictional force between them is small. The second corrugated sheet material 3 is much smaller than when two flat sheet materials 2 directly contact each other.
When a force T in the circumferential direction is applied to the two flat plate members 2 sandwiching it, the two flat plate members 2 and the second corrugated plate member 3 can easily slide in the circumferential direction, and therefore the honeycomb The thermal stress generated in the body is relieved.

In the above embodiment, the second corrugated sheet material 3
Between the two corrugated sheet materials 2 and the two corrugated sheet materials 2 are not joined by a brazing material, and between the other corrugated sheet materials 1 and the flat sheet material 2 are all brazed materials. It is generally joined. Therefore, since the honeycomb body can sufficiently maintain its shape against the force applied in the axial direction, telescoping does not occur in the honeycomb body, but when the axial length of the honeycomb body is short (for example, 25
(mm or less), the axial shape of the honeycomb body becomes unstable, and telescoping may occur. In such a case, telescoping can be prevented by joining a surface on one side of the second corrugated sheet material 3 and the flat plate material 2 in contact with the surface with a brazing material,
Moreover, since the surface opposite to the second corrugated sheet material 3 can slide freely with the flat sheet material 2, the durability of the honeycomb body does not change.

When the second corrugated sheet material 3 to be inserted in the range of 2 to 3 layers forming the outer peripheral portion of the honeycomb body is formed to have a shape in which the mountain height is smaller than that of the corrugated sheet material 1 and the number of cells is large, Compared with the catalyst efficiency for exhaust gas with a high flow rate of the part,
It is possible to improve the catalyst efficiency with respect to exhaust gas having a low flow velocity in the outer peripheral portion.

The second corrugated sheet material 3 is formed by using a metal plate whose surface is previously coated with an aluminum oxide coating layer, or an aluminum oxide coating layer is formed on the surface of the metal plate after being formed into a corrugated shape. If formed by applying, since the aluminum oxide coating layer is extremely stable, it is possible to prevent a metal touch between the second corrugated sheet material 3 and the flat plate material 2 in contact therewith, so that the contact is achieved. Sliding and deformation between the two at the location becomes much easier than in the case where the coating layer is not applied, and it is effective in improving the durability of the honeycomb body.

[0035]

As described above, the present invention provides a metal carrier in which two flat plate materials forming at least two layers from the outer layer of a roll-shaped honeycomb body are stacked, and the flat plate materials are not joined. , The second corrugated sheet material is arranged between the two flat sheet materials so that the two flat sheet materials and the second corrugated sheet material contact each other with an extremely small area. The frictional force is extremely small compared to the case where they directly contact each other, and the two flat plate materials and the second flat plate material can easily slide in the circumferential direction. Since the surface area is small, it can be easily deformed in the radial direction, so that the thermal stress of the honeycomb body is relieved and the durability of the metal carrier is improved.

When the length of the honeycomb body in the axial direction is short, the one side surface of the second corrugated sheet material is joined to the flat plate material which is in contact with the second corrugated sheet material, without lowering the durability of the honeycomb body. It is effective in preventing telescoping.

If the peak height of the second corrugated sheet material disposed on the outer peripheral portion of the honeycomb body is made smaller than the peak heights of the other corrugated sheet materials to have a shape having a large number of cells, a honeycomb body having a slow exhaust gas flow rate can be obtained. Since the catalyst efficiency of the outer peripheral portion is improved, there is an effect that the catalyst efficiency of the entire honeycomb body is improved.

Further, if the surface of the second corrugated sheet material is provided with an aluminum oxide coating layer, the metal touch between the second corrugated sheet material and the flat sheet material can be completely prevented, so that the sliding and deformation of the sheet materials at the contact point can be further prevented. Since this is easy, the durability of the honeycomb body is improved.

[Brief description of drawings]

FIG. 1 is a schematic view of a metal carrier for a catalyst device of the present invention, in which (A) is a schematic partial cross-sectional view showing a configuration of a plate material,
(B) is a cross-sectional view perpendicular to the axis of the honeycomb body formed by winding the plate material of (A) in a roll shape.

FIG. 2 is a schematic view of another metal carrier for a catalyst device of the present invention, (A) is a schematic partial cross-sectional view of a plate material having a different configuration from FIG. 1 (A), and (B) is a plate material of (A). FIG. 3 is a cross-sectional view perpendicular to the axis of a honeycomb body formed by winding a honeycomb into a roll shape.

FIG. 3 is a schematic view of another metal carrier for a catalyst device of the present invention, (A) is a schematic partial cross-sectional view of a plate material having a configuration different from that of FIG. 1 (A), and (B) is a plate material of (A). FIG. 3 is a cross-sectional view perpendicular to the axis of a honeycomb body formed by winding a honeycomb into a roll shape.

FIG. 4 is a schematic view of another metal carrier for a catalyst device of the present invention, where (A) is a schematic partial cross-sectional view of a plate material having a configuration different from that of FIG. 1 (A), and (B) is a plate material of (A). FIG. 3 is a cross-sectional view perpendicular to the axis of a honeycomb body formed by winding a honeycomb into a roll shape.

FIG. 5 is a schematic view of another metal carrier for a catalyst device of the present invention, (A) is a schematic partial cross-sectional view of a plate material having a configuration different from that of FIG. 1 (A), and (B) is a plate material of (A). FIG. 3 is a cross-sectional view perpendicular to the axis of a honeycomb body formed by winding a honeycomb into a roll shape.

[Fig. 6] Fig. 6 is a partial cross-sectional view of a honeycomb body of a metal carrier for a catalyst device of the present invention, which is an explanatory view when a thermal stress acts in a radial direction.

[Fig. 7] Fig. 7 is a partial cross-sectional view of a honeycomb body of a metal carrier for a catalyst device of the present invention, which is an explanatory view when a thermal stress acts in a circumferential direction.

FIG. 8 is a schematic view of a metal carrier for a catalyst device according to a conventional technique, (A) is a schematic partial cross-sectional view showing the configuration of a plate material, and (B) is a plate material of (A) wound in a roll shape. It is a perspective view of the formed honeycomb body.

9A and 9B are schematic views of another metal carrier for a catalyst device according to the prior art, in which FIG. 9A is a schematic partial cross-sectional view showing the structure of a plate member, and FIG. 9B is a plate member of FIG. It is a perspective view of the honeycomb body formed by turning.

FIG. 10 is an explanatory diagram when a thermal stress acts in a radial direction on the plate material shown in FIG. 9 (A).

FIG. 11 is an explanatory diagram in the case where thermal stress acts in the circumferential direction on the plate material shown in FIG. 9 (A).

[Explanation of symbols]

1,32-wave plate 2,2 _{1, 2} 2, 31 flat plate 3,3 _1, 3 _{2, 3} 3, 3 ₄ second wave plate 11,12,13,14,15,34,34a honeycomb body 30 , 40 Metal carrier 35 Outer cylinder R, T Direction of force due to thermal stress

Claims (4)

[Claims] 1. A corrugated sheet material formed by bending a strip-shaped thin metal plate to form a 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 to roll. Formed into a honeycomb body having a large number of layered mesh-like ventilation passages, at least two flat plates are stacked in the range of at least two layers from the outside, and the two flat plates are bonded to each other. In the metal carrier for a catalyst device formed without being formed, a second corrugated sheet material, in which a strip-shaped thin metal plate is bent to form continuous corrugated irregularities, is at least one layer of the honeycomb body. The metal carrier for a catalyst device, wherein the metal carrier is disposed between the two flat plate materials without being joined. 2. The metal plate forming the second corrugated sheet material,
The metal carrier for a catalyst device according to claim 1, which has an aluminum oxide coating layer on its surface in advance. 3. The metal carrier for a catalyst device according to claim 1, wherein the second corrugated sheet material has an aluminum oxide coating layer formed on the surface after shaping the metal sheet into a corrugated shape. 4. The surface on one side of the second corrugated sheet material is
The metal carrier for a catalyst device according to any one of claims 1 to 3, which is joined to one of the stacked flat plate members.