JPH08131840A - Metal carrier for electric heating type catalyst device - Google Patents

Abstract

PURPOSE: To provide a metal carrier for an electric heating type catalyst device having a rolled honeycomb body, simple in insulating structure, easily responsible for severe design requirement concerning to electric resistance, easy in production, low in cost and high in durability. CONSTITUTION: A honeycomb body 11 is formed by laminating a corrugated plate 1 and plural sheets of flat plates 2, inserting an insulating corrugated plate 3 between two adjacent flat plates, and rolling these sheets 2. Conductive parts A, B are formed on the ends of plates corresponding to the starting and ending ends for rolling. As for the insulating corrugated plate 3, Al-contg. ferrite stainless steel is used and is heated in an oxidative atmosphere to form aluminum oxide coating films on both surfaces. The peak height in the insulating wavy plate 3 is specified to >=0.5mm, and the electric resistance of the honeycomb body can be changed to satisfy the requirements by changing the peak height, number of sheets of flat plates, or thickness of the plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst carrier metal carrier used in an exhaust gas purifying apparatus for an internal combustion engine, and more particularly to an electrically heated metal carrier carrier.

[0002]

2. Description of the Related Art A metal carrier for a catalyst device used in a conventional exhaust gas purifying apparatus has a brazing filler metal interposed between a thin metal flat plate and a corrugated plate, and the flat plate and the corrugated plate are superposed and rolled into a roll from the center. A honeycomb body is formed, a brazing material is melted using a high vacuum furnace, and joining is performed at a 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 and the corrugated plate. A honeycomb carrier formed in such a manner and housed in a metal outer cylinder is known as a metal carrier for a catalyst device. (For example, JP-A-56-4373).

A catalyst supporting layer is formed on the surface of the honeycomb passage of the honeycomb body, and a noble metal catalyst is supported on the catalyst supporting layer to serve as an exhaust gas purifying catalyst. HC, CO, NO _x in the exhaust gas is provided in the exhaust passage of the internal combustion engine.
Etc. Since it is necessary to secure as large a honeycomb passage area as possible in a limited volume, the thickness of the flat plate and the corrugated plate is made as thin as possible within a range where strength can be maintained.

Since the catalytic reaction of the noble metal catalyst supported on the catalyst supporting layer described above is promoted in a high temperature environment to some extent, the catalyst device of the internal combustion engine is exposed to the exhaust gas at a temperature as high as possible. It is provided near the exhaust valve.

However, since the temperature of the exhaust gas is low at the time of starting the internal combustion engine, even such a catalyst device does not sufficiently perform the catalytic reaction, and therefore HC and C in the exhaust gas are not generated.
The ability to purify O, NO _x, etc. becomes insufficient. In order to eliminate this drawback, a metal carrier 50 for an electrically heated catalyst device as shown in FIG. 4 is disclosed.

In FIG. 4, three layers in which the flat plate member 51 and the corrugated plate member 52 are overlapped are further stacked to form a honeycomb body 53 having a toe-shaped cross section and wound from the central portion, and the outside is electrically insulated. Conductor connecting portions A and B, which are covered with a layer 54, are further housed in the outer cylinder 55, penetrate the outer cylinder 55 and the insulating layer 54, and are electrically connected to both ends of the plate material, are provided. Void 5 for insulation in the portion where the plate materials overlap each other
6 is provided. In order to hold this gap 56,
A rod-shaped support 57 is provided in each layer forming the honeycomb body. The honeycomb body 53 formed in this way is
When the conductor connecting portions A and B are connected to a power source (not shown), a heating element having the entire length of the plate material as an electric resistance body is formed, and thus the heating is performed by Joule heat. Therefore, when the low temperature exhaust gas discharged at the time of starting the engine passes through the honeycomb body 53, the catalytic reaction is easily promoted by the heated catalyst supporting layer.

The electric resistance value of the honeycomb body 53 is equal to that of the flat plate material 5.
It can be adjusted by the number of layers formed by laminating 1 and the corrugated sheet material 52 one by one. That is, the overall resistance value can be adjusted by decreasing the number of layers when the outer diameter of the honeycomb body 53 is small and increasing the number of layers when the outer diameter is large.

As another example, as shown in FIG. 5, a large number of curved bending members 61 extend radially from the central portion, and between two adjacent bending members 61, a wave height gradually increases from the central portion. The corrugated sheet material 62 having a large size is arranged to form a cylindrical honeycomb body 63. On the outer peripheral surface of the honeycomb body, the outer peripheral electrodes 6 are arranged in the same number as the corrugated plate material 62 at equal intervals.
4 are provided in series, and the reverse part of the honeycomb body is
Individual center electrodes 65 are provided. The outer periphery of the outer peripheral electrode 64 is covered with an electric insulating layer 66 to insulate the outer peripheral electrode 64 from the outer cylinder 67 surrounding the outer periphery thereof. By applying a voltage from a power source (not shown) between the center electrode 65 and the outer peripheral electrode 64 of the honeycomb body 63 formed in this way, an electric current flows in the honeycomb body 63 to generate Joule heat. A metal carrier 60 in which the entire honeycomb body is heated is disclosed.

As a new technology, a metal carrier for an electrically heated catalyst device forming a roll-shaped honeycomb body,
The following metal carriers have been developed. That is, the configuration of the plate material forming the roll-shaped honeycomb body is, as shown in FIG. 6, one corrugated plate material 71 and a plurality of flat plate materials (here, three flat plate materials 72, 73, 74). ), And at least one of the plate members (here, the flat plate member 73) is provided with the electrically insulating coating layer 73a, and the brazing member 75 is interposed on the side of the flat plate members 72, 74 that contacts the corrugated plate member 71. Then, they are wound into a roll to form a honeycomb body. The honeycomb body forms a heating element having the entire length of the plate material as an electric resistor by connecting the winding start and winding end of the roll, that is, both ends of the plate material to a power source (not shown).
In order to obtain a required electric resistance value suitable for the outer diameter and length of the honeycomb body, it can be easily achieved by increasing or decreasing the number of flat plate members or changing the thickness of the plate members.

A method of applying the electrically insulating coating layer 73a to one flat plate material 73 among the plurality of flat plate materials shown in FIG.
There are three methods: That is, (1) a ferritic stainless steel containing aluminum is used as a plate material and heated in an oxidizing atmosphere to form aluminum oxide coatings on both front and back surfaces of the plate material. (2) An aluminum oxide film is formed on the surface (one surface or both surfaces) of the plate material by a method such as PVD. (3) The plate material is dipped in molten aluminum to coat both surfaces with aluminum, and then heated in an oxidizing atmosphere to form an aluminum oxide film on both surfaces of the plate material.

[0011]

In the conventional metal carrier for an electrically heated catalyst device shown in FIG. 4 described above, three more layers in which a flat plate material and a corrugated plate material are overlapped are stacked and wound in a bellows shape from the central portion. By turning to form a honeycomb body, the outer side of which is covered with an electrically insulating layer, is further housed in an outer cylinder, and a conductor connecting portion that penetrates the outer cylinder and the insulating layer and is electrically connected to both ends of the plate material is provided. Further, an insulating void is provided to prevent the three layers of plate materials from contacting each other, and the honeycomb body is supported by a plurality of rod-shaped supports to hold the void. Therefore, three insulations of the outer cylinder and the conductor connecting portion, the outer cylinder and the honeycomb body, and the honeycomb body itself are required, which makes the structure very complicated, resulting in high manufacturing cost and poor durability.

Further, the metal carrier shown in FIG. 5 has a large number of curved members and corrugated plate members arranged between them, and also has a large number of outer peripheral electrodes arranged outside the honeycomb body, which complicates the structure. Also, in order to change the electric resistance value between the central electrode and the peripheral electrode of the honeycomb body, it is possible to change the plate thickness of the plate material or the number of cells of the honeycomb body, There is a drawback that the degree of freedom in designing about them is small and it is not possible to satisfy the detailed specifications required by the customer.Moreover, since an insulating layer must be provided between the outer peripheral electrode and the outer cylinder, the manufacturing cost is high. Moreover, there is a drawback that the durability is poor.

Further, in the honeycomb body formed by winding the plate material shown in FIG. 6 in a roll shape, the layers of the roll forming the honeycomb body are insulated by at least one plate material having an electrically insulating coating layer. There are three methods as described above as a method for forming the electrically insulating coating layer on the plate material, and a roll-shaped honeycomb body is formed by using the plate material having the electrically insulating layer formed by these methods. If formed, it has the following drawbacks.

That is, temporarily, the corrugated plate material 71 or the flat plate material 72 is used.
Alternatively, if the flat insulating material 74 is provided with an electrically insulating coating layer of an aluminum oxide film by the above-mentioned method, since the coating is very stable, the plate material provided with the electrically insulating coating layer is brazed to another plate material. Can not. As a result, it becomes impossible to maintain the shape of the honeycomb body in a roll shape, so that the above-mentioned plate materials 71, 72, 74 cannot be coated. Therefore, as the only method, it is possible to form a roll-shaped honeycomb body by applying a coating to the flat plate material 73 to form an electric insulating layer. This form is one corrugated sheet material and 3
It is the basis for forming a roll-shaped honeycomb body by using a flat plate material.

However, when the honeycomb body formed by winding the plate material shown in FIG. 6 in a roll shape is used as a metal carrier for an electrically heated catalyst device and heating and cooling are repeated, the electrically insulating coating layer 73a is formed. Since the applied flat plate material 73 and the upper and lower flat plate materials 72 and 74 sandwiching the flat plate material 73 are not brazed, they can freely expand and contract with each other.
The electrically insulating coating layer 73a is likely to be damaged due to abrasion at the contact point between the two plate materials. Therefore, the flat plate materials 72 and 73
Between them or between the flat plate members 74 and 73 causes a short circuit, resulting in a short circuit, resulting in a partial decrease in the electric resistance value, and finally, a short circuit portion is melted. . In order to prevent such a problem, the plate thickness of the flat plate material 73 having the electrically insulating coating layer 73a can be considerably prevented by increasing the plate thickness to, for example, 0.5 mm or more. It is difficult to form such a honeycomb body.

An object of the present invention is to provide a metal carrier for an electrically heated catalyst device, which has a simple insulating structure and can easily meet the detailed design requirements for electric resistance.
Another object of the present invention is to provide a metal carrier for an electrically heated catalyst device which is easy to manufacture, low in cost and high in durability.

[0017]

MEANS FOR SOLVING THE PROBLEMS The metal carrier for an electrically heated catalyst device of the present invention comprises a corrugated sheet material formed by bending a thin metal sheet in the form of a strip to form continuous corrugation, and a flat corrugated sheet material. A metal carrier for a catalyst device that forms a honeycomb body having a large number of mesh-like ventilation passages, which is formed by a plurality of flat plate materials made of a thin metal plate in a strip shape being in contact with each other and overlapping with each other and wound into a roll shape. In, a corrugated plate for insulation having an electrically insulating coating layer is interposed between two adjacent sheets of a plurality of flat plate materials to electrically insulate layers wound in a roll shape of a honeycomb body. In addition, conductor connection portions for connecting to a power source are provided at the ends of the plate material at the beginning and end of winding of the honeycomb body.

The second metal carrier for an electric heating type catalyst device of the present invention has a flat corrugated sheet material and one corrugated sheet material in which a corrugated thin metal plate is bent to form a continuous corrugation. A plurality of mesh-like ventilation passages formed by stacking at least two layers of layers formed by abutting and overlapping a plurality of flat plate materials made of thin metal plates and rolling In the metal carrier for a catalyst device forming a honeycomb body, at least one of the stacked layers is
An insulating corrugated sheet having an electrically insulating coating layer is interposed between two adjacent sheets of a plurality of flat plate materials to electrically insulate layers wound in a roll shape of a honeycomb body, In addition, conductor connection portions for connecting to a power source are provided at the ends of the plate material at the beginning and end of winding of the honeycomb body.

It is desirable that the insulating corrugated plate of the metal carrier for the electric heating type catalyst device and the two flat plate members in contact with the corrugated plate are not joined by a brazing material.

[0020]

Since the corrugated plate for insulation is used to insulate the layers of the rolled honeycomb body from each other, the distance between the two flat plate members requiring insulation can be widened, and the insulation performance between the layers can be improved. Since the insulating corrugated plate and the two flat plate materials are not joined by the brazing material, during expansion and contraction by heating and cooling,
The two flat plates can slide on each other via the insulating corrugated plate. The contact area where the two flat plates are in contact with the insulating corrugated plate is
Since it is much smaller than in the case of a normal flat plate double structure in which two flat plate materials are in direct contact with each other, the resistance of the sliding surface is also small and slippage easily occurs, so that the thermal stress of the honeycomb body is relieved and the honeycomb body is relieved. The overall durability is improved.

For a plate material forming a roll-shaped honeycomb body,
Since a plurality of flat plate materials are used, the electrical resistance value of the honeycomb body can be easily changed by increasing or decreasing the number or thickness. Furthermore, the number of windings of the honeycomb body can be changed by changing the peak height of the insulating corrugated sheet, so that the electric resistance value can be easily adjusted.

[0022]

Next, an embodiment 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 an electrically heated catalyst device of the present invention, FIG. 1 (A) is a schematic partial cross-sectional schematic view showing the configuration of a plate material, and FIG. 1 (B) is FIG. (A)
3 is a schematic view of a cross section of a roll-shaped honeycomb body formed by winding the plate material of FIG.

In FIG. 1A, a corrugated sheet material 1 is one sheet material in which a strip-shaped thin metal sheet is bent to form continuous corrugation, and a flat sheet material 2 is a flat strip-shaped thin metal sheet. It is two adjacent plate materials made of. These two flat plate materials 2
In order to electrically insulate the gaps, one insulating corrugated plate 3 is provided. As the corrugated plate 3, a metal plate having substantially the same shape as the corrugated plate material 1 and made of ferritic stainless steel containing aluminum is used. To apply the electrically insulating coating layer to the corrugated plate 3, heating is performed in an oxidizing atmosphere to form an aluminum oxide coating on the surface. The height of the corrugated peaks of the corrugated sheet 3 is
The thickness is 0.5 mm or more in order to reliably maintain the electrical insulation between the two flat plate materials 2.

The corrugated sheet material 1 thus obtained, the two flat sheet materials 2 and the insulating corrugated sheet 3 sandwiched between the flat sheet materials 2 are superposed, and further the flat sheet material for joining the corrugated sheet materials 1 to each other. 1 and the brazing material 4 is inserted between them and wound into a roll,
A honeycomb body 5 as shown in (B) is formed. Therefore,
The insulating corrugated plate 3 and the upper and lower flat plate members 2 that sandwich the insulating corrugated plate 3 are not joined by a brazing material. The layers of the roll of the honeycomb body 5 are electrically insulated by the insulating corrugated plate 3. When a power source is connected to the conductor connection portions A and B provided at the winding start and winding end portions of the plate material, the entire length of the plate material serves as an electric resistor, so that the honeycomb body 5 is heated and electrically heated. Functions as a metal carrier for catalytic devices. Figure 2
1B is a schematic partial cross-sectional view showing a state in which two flat plate members 2 sandwiching the corrugated insulating plate 3 of the honeycomb body of FIG. 1B slide, and the flat plate members 2 have a degree of freedom with respect to expansion and contraction due to heat. Since it has, and is in contact with the insulating corrugated plate 3 with an extremely small contact area,
Since they can slide on each other with a small resistance, the thermal stress generated in the honeycomb body 5 is relaxed, and the durability is improved.

The electric resistance value of the honeycomb body 5 needs to be variously set according to the specifications required by the customer. In the honeycomb body according to the present invention, since a plurality of flat plate materials are used, the resistance value can be increased or decreased. Can be set variously, and can also be set by changing the plate thickness of the metal plate. Further, by changing the peak height of the insulating corrugated plate 3, the number of rolls of the honeycomb body, that is, the length of the plate material is changed, so that it is possible to easily meet the request for changing the resistance value.

FIG. 3 is a schematic partial cross-sectional view showing the construction of a plate material used in the second metal carrier for an electrically heated catalyst device of the present invention.

In FIG. 3, the corrugated sheet material 11, the flat plate material 12 and the insulating corrugated sheet 13 are the corrugated sheet material 1 and the corrugated sheet material 1 shown in FIG. 1, respectively.
It corresponds to the flat plate member 2 and the insulating corrugated plate 3. The corrugated sheet material 11, the two flat plate materials 12 and the insulating corrugated sheet 13 are stacked to form the first layer 10, and further the second layer 20 is the corrugated sheet material 2
It is formed of one and two flat plate members 22 and is laminated on the first layer 10, and two layers of the first layer 10 and the second layer 20 are rolled together to form a honeycomb body. It The layers of the roll of the honeycomb body are electrically insulated by the insulating corrugated sheet 13. If a power source is connected to the conductor connection portions (not shown) provided at the winding start and winding end portions of the plate material, the entire length of the plate material becomes an electric resistor, so that the entire honeycomb body is heated. Therefore, it functions as a metal carrier for an electrically heated catalyst device.

By forming the honeycomb body by stacking the first layer and the second layer in this manner, metal carriers having different resistance values can be obtained. Furthermore, in this metal carrier,
In the same manner as the case shown in Fig. 1, a plurality of flat plate materials 1 are used
The resistance value of the metal carrier can be easily changed by increasing or decreasing the number of sheets 2 and 22, changing the plate thickness of the plate material, and changing the peak height of the insulating corrugated plate 13, so that the customer's detailed requirements for the resistance value can be met. Can respond well.

When a roll-shaped honeycomb body having an axial length of, for example, less than 5 mm is formed using the plate material having the structure shown in FIG. 1 (A), the corrugated plate material 1 and the flat plate material 2 are used. Only by joining the gaps with the brazing material 4, the shape of the honeycomb body becomes unstable, and telescoping is likely to occur.
In such a case, a brazing material is inserted also on one side of the corrugated plate 3 without providing the insulating corrugated plate 3 with the electrically insulating coating layer, and the flat plate member 2 is formed.
By forming a honeycomb body which is not joined with telescoping by heating the whole honeycomb body in an oxidizing atmosphere, an electrically insulating coating layer can be formed on the surface of the corrugated sheet 3 which is not joined. A honeycomb body having a short shape can be obtained.

The insulating corrugated plate 3 is made of ferritic stainless steel containing aluminum. However, when a material not containing aluminum is used, an aluminum oxide film is formed on the surface of the plate material by a method such as PVD. Or,
Alternatively, the plate material may be immersed in molten aluminum to coat the aluminum, and then heated in an oxidizing atmosphere to form an aluminum oxide film on the surface of the plate material.

[0031]

As described above, according to the present invention, one corrugated sheet material and a plurality of flat sheet materials are overlapped with each other, and an insulating corrugated sheet is inserted between two adjacent flat sheet materials. Are wound together in a roll shape to form a honeycomb body, and the insulating corrugated plate and the upper and lower flat plate materials that sandwich the corrugated plate are not joined to each other, so that the two flat plate materials do not expand or contract due to heat. Since it has a degree of freedom and can relieve the thermal stress generated in the honeycomb body, it has the effect of providing a durable metal carrier. Furthermore, it does not use voids or insulating materials for insulation, The corrugated sheet has a durable aluminum oxide coating layer for durability, and the structure is simple, so the cost is low and the corrugated sheet for insulation is 0.5 mm or more. Local damage to the electrically insulating coating layer In this case, the insulating property between the two flat plates is ensured, and the aluminum oxide film formed by heating in the atmosphere has a self-repair ability, so that the insulating property is always ensured even when damaged. effective.

Various required specifications for the electric resistance value of the carrier can be easily designed by changing the number of flat plates, the thickness of plates, or the height of the corrugated insulating plate. Even if the honeycomb body has an extremely short axial length, there is an effect that a metal carrier that does not cause telescoping can be obtained by joining one surface of the insulating corrugated plate to a flat plate material.

[Brief description of drawings]

FIG. 1 is a diagram of a metal carrier for an electrically heated catalyst device of the present invention, FIG. 1 (A) is a schematic partial cross-sectional schematic view showing the structure of a plate material, and FIG. 1 (B) is FIG. 1 (A). 2 is a schematic view of a cross section of a roll-shaped honeycomb body formed by the plate material of FIG.

FIG. 2 is an explanatory diagram showing a state in which thermal stress acts on the honeycomb body of FIG. 1 (B).

FIG. 3 is a schematic partial cross-sectional view showing the configuration of a plate member of the second metal carrier for an electrically heated catalyst device of the present invention.

FIG. 4 is a schematic view of a cross section of a metal carrier for an electrically heated catalytic device according to the prior art, which is perpendicular to the axis.

FIG. 5 is a schematic view of another section of a metal carrier for an electrically heated catalytic device according to the prior art, which is perpendicular to the axis.

FIG. 6 is a schematic partial cross-sectional view showing the configuration of a plate member of another conventional metal carrier for an electrically heated catalyst device.

[Explanation of symbols]

 1, 11, 21, 52, 62, 71 Corrugated sheet material 2, 12, 22, 51, 72, 73, 74 Flat plate material 3, 13 Insulating corrugated sheet 54, 66 Electrical insulating layer 73a Electrical insulating coating layer 4, 75 Brazing material 10 First layer 20 Second layer 50,60 Metal carrier 5,53,63 Honeycomb body 55,67 Outer cylinder 56 Void 57 Support 61 Curved material 64 Peripheral electrode 65 Center electrode A, B Conductor connection part

Claims (3)

[Claims] 1. A single corrugated sheet material in which a strip-shaped thin metal plate is bent to form continuous corrugated irregularities, and a plurality of flat sheet materials made of flat strip-shaped thin metal plates are mutually disposed. In a metal carrier for a catalyst device, which is formed by rolling in a roll shape so as to be in contact with each other and overlapped with each other, between the two adjacent flat plates among the plurality of flat plates. The insulating corrugated sheet having an electrically insulating coating layer is interposed to electrically insulate the layers wound in a roll shape of the honeycomb body, and the plate material of the winding start and the winding end of the honeycomb body A metal carrier for an electrically heated catalyst device, characterized in that it has a conductor connecting portion for connecting to a power source at an end thereof. 2. A corrugated sheet material in which a strip-shaped thin metal plate is bent to form continuous corrugations and a plurality of flat sheet materials made of flat strip-shaped thin metal plates are mutually disposed. In a metal carrier for a catalyst device, which is a honeycomb body having a large number of mesh-like ventilation passages, at least two layers formed by abutting and overlapping each other are stacked and wound in a roll shape. At least one of the layers is formed into a roll shape of the honeycomb body by interposing an insulating corrugated plate having an electrically insulating coating layer between two adjacent ones of the plurality of flat plate materials. Electrically insulating the wound layers, also characterized by having a conductor connection portion for connecting to a power source at the end of the plate material at the beginning and end of the winding of the honeycomb body,
Metal carrier for electrically heated catalytic devices. 3. The metal for an electrically heated catalytic device according to claim 1, wherein the insulating corrugated plate and the two flat plate members in contact with the corrugated plate are not joined by a brazing material. Carrier.