JP3716031B2 - Metal carrier for catalyst equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal carrier for a catalyst device that forms a honeycomb body used in an exhaust gas purification device of an internal combustion engine, and more particularly to a metal carrier for a catalyst device of a rolled honeycomb body.
[0002]
[Prior art]
As shown in FIG. 2 , the metal carrier for a catalyst device used in a conventional exhaust gas purifying device has a brazing material 33 in a range X that extends between the thin metal plate material 32 and the corrugated plate material 31 over the entire axial length of the plate material. 2, the flat plate material 32 and the corrugated plate material 31 are overlapped, and as shown in FIG. 2 (B), a honeycomb body 34 is formed by rolling it from the center to form a brazing material 33 using a vacuum furnace. It was melted and joined at the catalyst portion of the plate. A Ni-based brazing material was used for the brazing material, and a ferritic stainless steel material was used for the flat plate material and the corrugated sheet 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, Japanese Patent Laid-Open No. 56-4373).
[0003]
A catalyst support layer made of alumina or the like is formed over the entire length in the axial direction on the honeycomb passage surface of the honeycomb body, and a noble metal catalyst is supported on the catalyst support layer to serve as an exhaust gas purification catalyst. And it is disposed in an exhaust passage of an internal combustion engine for purifying HC in exhaust gas, CO, and NO _X, and the like. In addition, since it is necessary to secure as much honeycomb passage area as possible in a limited volume, the thickness of the flat plate and the corrugated plate is as thin as possible within a range in which the strength can be maintained.
[0004]
In the conventional metal carrier for a catalyst device described above, the flow rate of the exhaust gas passing through the honeycomb body increases as it reaches the inner layer portion from the outer layer portion of the honeycomb body. Due to heat generation and heat dissipation from the outer cylinder, a temperature distribution is generated in which the inner layer portion is hotter and the outer layer portion is colder. Furthermore, on the gas inlet side of the honeycomb body, the catalytic reaction occurs particularly actively due to the inflow of high-temperature exhaust gas. Therefore, the temperature rise and cooling speed applied to the brazed part is high, and a thermal shock is applied to the brazed part. Cheap.
[0005]
Therefore, compared with the outlet side in the gas inlet side of the metal carrier plate material and sheet heat stress generated in the brazing portion becomes large, as shown in FIG. 3 (A), provided brazing position two or more locations In such a case, there is no strain escape due to thermal stress, and as shown in FIG. 3 (B), the honeycomb body is easily deformed or broken by cracks in the brazed portion, and as shown in FIG. 4 (A), The brazing material 33 and the brazing influence part 37 of the brazing part are disadvantageous in that they deteriorate due to oxidation at a high temperature and the strength becomes weak.
[0006]
To eliminate these drawbacks, as shown in FIG. 5 (A), (B) , the flat plate 32 at two or more layers in the range from outside the two-ply, between the two that is simply overlaid without bonding And a so-called full-layer flat plate in which a flat plate material from the start to the end of winding of the honeycomb body is doubled. A metal carrier including a double-structured honeycomb body is also disclosed. In both of these two types of flat plate honeycomb structures, the flat plate and the flat plate are not joined by the brazing material, and the thermal stress generated by heating and cooling is caused by the sliding between the two flat plates. Absorption is mitigated to prevent cracks in the brazed part.
[0007]
To eliminate the drawbacks Mataro with portions strength for oxidative degradation decreases, as shown in FIG. 4 (B), the diffusion depth of the base material 36 of the brazing material 33, i.e. the depth of the braze-affected zone 37 A joining method that suppresses the thickness to less than the thickness of the base material 36 has been developed.
[0008]
[Problems to be solved by the invention]
In the above-described conventional honeycomb body having a flat double plate structure, since the double plate members are not joined by the brazing material, cracks in the brazed portion between the corrugated plate material and the flat plate material are caused. In the case of severe operating conditions involving severe vibrations, the disadvantage is that a so-called telescoping phenomenon as shown in FIG. 6 occurs in which two unjoined flat plates are displaced in the axial direction. In particular, when the honeycomb body has a short axial length (for example, 30 mm or less), or when the honeycomb body has a large outer diameter, a telescoping phenomenon tends to occur.
[0009]
In order to eliminate this defect, a honeycomb body having a flat plate double structure is contacted in series downstream of the honeycomb body, and another honeycomb body in which the plate members are joined by a brazing material and does not carry a catalyst is arranged to form the former honeycomb body. Although there is a method of suppressing the telescoping phenomenon that occurs, there is a drawback that the manufacturing cost increases.
[0010]
Further, in the above-described processing method for suppressing the diffusion depth of the brazing material to the base material to prevent the strength of the brazing portion from being reduced by oxidation, the oxidation life of the brazing portion can be extended. The effect is not sufficient, and the disadvantage that the honeycomb body falls off is not solved.
[0011]
An object of the present invention is to provide a metal carrier capable of relaxing thermal stress generated in a honeycomb body and preventing deformation of the honeycomb body and cracking of a brazed portion.
[0012]
[Means for Solving the Problems]
In the metal carrier for a catalyst device of the present invention, a corrugated sheet material formed by bending a strip-shaped thin metal plate to form continuous corrugated irregularities and a flat plate material composed of a flat strip-shaped thin metal plate are in contact with each other. In a metal carrier for a catalyst device having a honeycomb body including a large number of mesh-shaped passages that are overlapped and joined by a brazing material and wound in a roll shape, and an outer cylinder that covers an outer surface of the honeycomb body,
A brazing portion region of the brazing material for joining the corrugated plate member and the flat plate member, and the honeycomb body and the outer cylinder is provided in a range from the axial central portion of the honeycomb body to the gas outlet portion, and the catalyst of the honeycomb body is provided. The carrying range is provided in a range from the gas inlet part to the front of the brazing part region. In addition, the outer cylinder covers the downstream side from the central portion in the axial direction of the honeycomb body, and is joined to the honeycomb body by the brazing material in the brazed portion region of the honeycomb body.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram of an embodiment of a metal carrier for a catalyst device according to the present invention. FIG. 1 (A) is a longitudinal sectional view including a shaft, and FIG. 1 (B) is a diagram showing each of the components constituting FIG. FIG. 1C is a schematic longitudinal sectional view showing the relationship between members, and FIG. 1C is a longitudinal sectional view including the shaft of another embodiment.
[0014]
1A and 1B, a corrugated sheet material 1 is a sheet material formed by bending a strip-shaped thin metal plate to form continuous corrugations, and a flat plate material 2 is formed from a flat strip-shaped thin metal plate. The two brazing members 3a and 3b in the form of narrow foils sandwiched between the plate members, and the overlapping plate members are rolled from one end in the longitudinal direction around the axis. The honeycomb body 4 is formed by being wound around.
[0015]
The range in the axial direction of the brazed part region 3 formed by the brazing materials 3a and 3b is within the range from the central part in the axial direction 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 4 b of the honeycomb body 4. This is to prevent melting of the brazing material, in particular, the molten brazing material from flowing out from the end edge of the outlet portion 4b. The axial width of the brazed portion region 3 is preferably 10 to 30% of the axial length of the honeycomb body 4. In FIG. 1, one brazing material 3 a and 3 b sandwiched between the flat plate material 2 and the corrugated plate material 1 is described, but the number is not necessarily limited to one.
[0016]
The range W in which the honeycomb body 4 carries the catalyst is a range from the gas inlet portion 4a of the honeycomb body 4 to 50 to 80% of the axial length of the honeycomb body 4. However, it should be 5 mm or more away from the brazing part region 3 so that the catalyst does not hit the brazing part.
[0017]
The outer cylinder 5 is a cylindrical cylinder formed of a metal plate having a thickness of 1 to 3 mm that covers the outer surface of the honeycomb body 4. The outer cylinder 5 is brazed to the honeycomb body 4 in the brazed portion region 3. In order to hold, it is fixed to a muffler (not shown) by welding.
[0018]
In the metal carrier shown in FIGS. 1A and 1B described above, brazing in the brazed portion region 3 having a narrow width is performed within the range from the axially central portion of the honeycomb body 4 to the outlet portion 4b. Further, since the axial width of the brazed portion region 3 is as narrow as 10 to 30% of the axial length of the honeycomb body 4, the corrugated sheet material 1 and the flat plate material that form the honeycomb body 4 upstream from the brazed portion region 3. Since the elongation due to the heat of 2 can freely extend toward the gas inlet side, the stress due to thermal strain between the plate members and between the honeycomb body 4 and the outer cylinder 5 is released.
[0019]
Further, since the range W in which the catalyst is supported is a 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 does not occur in the brazing part region 3, Therefore, since the temperature of the brazing part area | region 3 is kept lower than another part, the oxidation of a brazing part is prevented.
[0020]
FIG. 1C is a schematic vertical cross-sectional view of an embodiment in which the outer cylinder 5 in FIG. 1A is shortened to form an outer cylinder 5 a so as to cover the downstream side from the axial center of the honeycomb body 4. The axial length of the outer cylinder 5a in this case is set so as to cover 10 to 60% of the honeycomb body 4 from the end edge of the outlet portion 4b of the honeycomb body 4. By using the shortened outer cylinder 5a and releasing the gas inlet side outer peripheral surface of the honeycomb body 4 from the press by the outer cylinder, the stress due to expansion and contraction due to the heat 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 positive effect on the life of the honeycomb body 4.
[0025]
【The invention's effect】
Above-described manner, the present invention includes a honeycomb body formed by winding into a roll overlapping the wave plate and the flat plate material, the metal carrier comprising an outer cylinder covering the honeycomb body, the plate material the Judges and the honeycomb body and the outer The brazing part region of the brazing material that joins the cylinder is provided in the range from the central part of the honeycomb body to the gas outlet part, and the catalyst loading range is between the gas inlet part and the brazing part area. As a result, the honeycomb body can be easily stretched in the axial direction, no stress is generated between the plate materials, and the brazed part region is not subjected to heat generation due to the catalytic reaction, so that the temperature is kept low. If the length of the outer cylinder is provided so as to cover the downstream side from the axial center of the honeycomb body, the expansion in the radial direction of the honeycomb body is not hindered. Thermal stress applied to the upstream honeycomb body It can be reduced, an effect that the durability of the honeycomb body is further improved.
[Brief description of the drawings]
FIG. 1 is a view showing a longitudinal section of a metal carrier for a catalyst device according to the present invention, in which FIG. 1 (A) is a schematic longitudinal sectional view including a shaft, and FIG. FIG. 1C is a schematic vertical cross-sectional view including the axis of another metal carrier.
2A and 2B are diagrams of a conventional metal carrier for a catalyst device, in which FIG. 2A is a schematic cross-sectional view perpendicular to an axis showing the configuration of a plate material, and FIG. 2B is an external view of the metal carrier. FIG. 2C is a perspective view showing a range X in which a brazing material is interposed.
FIG. 3 is a schematic diagram of a longitudinal section including a shaft of a honeycomb body according to a conventional technique, FIG. 3 (A) is a diagram showing a position of brazing, and FIG. 3 (B) is a diagram showing deformation and fracture of a plate material. It is a figure which shows a state.
4A and 4B are schematic views showing a cross-section of a brazed portion of a plate material according to a conventional technique, in which FIG. 4A is a normal brazing method, and FIG. 4B is a joint in which the diffusion depth of the brazing material is limited. FIG.
5A and 5B are diagrams of a honeycomb body having a flat plate structure according to a conventional technique, in which FIG. 5A is a schematic cross-sectional view showing a configuration of a plate material, and FIG. 5B is a perspective view of the appearance of a metal carrier. FIG.
FIG. 6 is a schematic perspective view of the appearance showing the telescoping of a honeycomb body.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 31 Corrugated sheet material 2, 32 Flat plate material 3 Brazing part area | region 3a, 3b, 33 Brazing material 4 , 3, 4 , 34a Honeycomb body 4a Gas inlet part 4b Gas outlet part 5 , 5a , 3 5 Outer cylinder 10 3, 30 , 40 Metal carrier 36 Base material 37 Brazing influence part
W catalyst loading range X Range in which brazing material is interposed

Claims (2)

A corrugated sheet material formed by bending a strip-shaped thin metal plate to form continuous corrugated irregularities and a flat plate material made of a flat strip-shaped thin metal plate are in contact with each other and overlapped with each other, and are joined by a brazing material. In a metal carrier for a catalyst device having a honeycomb body provided with a large number of mesh-like passages formed by winding and an outer cylinder covering the outer surface of the honeycomb body,
The brazing material region of the brazing material joining the corrugated plate material and the flat plate material and the honeycomb body and the outer cylinder is in the range from the axial center to the gas outlet portion of the honeycomb body,
The metal carrier for a catalyst device, wherein a range for supporting the catalyst of the honeycomb body is between a gas inlet portion and a front side of the brazing portion region. 2. The metal for a catalyst device according to claim 1, wherein the outer cylinder covers a downstream side from the axially central portion of the honeycomb body and is joined to the honeycomb body by a brazing material in the brazing portion region of the honeycomb body. Carrier.

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