WO2024062718A1 - Metal honeycomb body, honeycomb unit, catalytic converter, method for manufacturing honeycomb unit, method for manufacturing catalytic converter, and method for manufacturing metal honeycomb body - Google Patents

Abstract

[Problem] The present invention addresses the problem of providing a plug for a winding-core hollow section, the plug posing no hindrance to light-off performance, regular purification performance, or plug shape maintenance characteristics. [Solution] Provided is a metal honeycomb body configured by winding a flat foil and an undulating foil about a prescribed axis, the flat foil and undulating foil being composed of metal foils, wherein the metal honeycomb body is characterized in that numerous through-holes are formed in the flat foil and/or the undulating foil, and a plug composed of a porous body is installed at one or both ends of a winding-core hollow section in the metal honeycomb body.

Description

Metal honeycomb body, honeycomb unit, catalytic converter, method for manufacturing a honeycomb unit, method for manufacturing a catalytic converter, and method for manufacturing a metal honeycomb body

The present invention relates to a metal honeycomb body having a winding core hollow portion.

As a purifying device for purifying vehicle exhaust gas, a metal honeycomb body in which flat foil and corrugated foil made of metal foil are wound around a predetermined axis is known. A winding core having a hollow structure is formed at the center. Since the winding core has low purification performance, it is required to reduce the exhaust gas flowing into the winding core.

Patent Document 1 discloses a purification device with improved purification performance by forming a large number of through holes in metal foil used for a metal honeycomb body.

Patent Document 2 discloses a metal catalyst carrier using a metal honeycomb body formed by winding a metal flat foil and a corrugated foil, in which a metal plug is arranged in the hollow part of the winding core to inhibit gas flow. The technology for setting this up is disclosed.

Patent Document 3 discloses that in a metal honeycomb body using a metal honeycomb body formed by winding a metal flat foil and a corrugated metal foil, starting ends of both metal foils at an axial end of a winding core hollow part are disclosed. A technique has been disclosed in which a restricting part is provided that restricts the flow of exhaust gas in a winding core part with a widened space between the winding core parts.

JP 2005-535454 A JP2006-281118A JP 2010-201413 A

Since a large number of through holes are formed in the metal foil described in Patent Document 1, the pressure loss in the gas conduction path becomes large. When the pressure loss of the gas passage becomes large, exhaust gas tends to escape from the hollow part of the winding core, and the effect (improvement of steady-state purification performance) of forming a large number of through holes cannot be fully enjoyed.

In the metal honeycomb body of Patent Document 2, since a dense metal plug is used, the heat capacity of the metal honeycomb body increases, and the light-off performance (temperature characteristics at which the purification performance of the catalyst is expressed) deteriorates. When through-holes are formed in the foil, the area of the foil material becomes smaller by the area of the holes, which suppresses the heat capacity and improves the light-off performance compared to a foil carrier without holes of the same volume. When a sealing plug is inserted, the heat capacity increases by the amount of the sealing plug, and the heat capacity reduction effect obtained by making holes in the foil is lost. Although the heat capacity can be reduced by shortening the length of the plug, the durability of the plug cannot be maintained because the connection length of the plug to the hollow part of the winding core is insufficient.

The metal honeycomb body of Patent Document 3 uses a method in which a restricting portion is provided by processing metal foil, so the heat capacity does not increase, but the durability of the restricting portion is insufficient due to insufficient strength.

In order to solve the above-mentioned problems, the metal honeycomb body of the present invention provides (1) a metal honeycomb body constructed by winding flat and corrugated metal foils around a predetermined axis; It is characterized in that a plug made of a porous material is disposed at one end or both ends of the hollow part of the winding core.

(2) The metal honeycomb body according to (1) above, wherein the flat foil and/or the corrugated foil has a large number of through holes formed therein.

(3) The metal honeycomb body according to (1) or (2) above, wherein the porous body has a structure in which a large number of metal pieces are joined with a brazing material.

(4) The metal piece is made of the same material as the metal foil, and the brazing material is made of the same material as the brazing material used to join the flat foil and the corrugated foil. The metal honeycomb body according to (3) above, characterized by:

(5) The metal honeycomb body according to (1) or (2) above, wherein the porous body is composed of a large number of metal pieces and an inorganic adhesive that adheres adjacent metal pieces to each other. .

(6) The metal honeycomb body according to any one of (1) to (5) above, wherein the porous body has a porosity of 7% or more and 85% or less.

(7) The above-mentioned (1), wherein the porous body is disposed at both ends of the core hollow part of the metal honeycomb body, and the porous body has a porosity of 70% or less. The metal honeycomb body according to any one of (6) to (6).

(8) Any one of (1) to (7) above, characterized in that the length in the axial direction of the porous body is 1 to 3 times the diameter of the hollow part of the winding core. Metal honeycomb body described in.

(9) A honeycomb unit comprising the metal honeycomb body according to any one of (1) to (8) above, and an outer cylinder in which the metal honeycomb body is housed.

(10) A catalytic converter in which a catalyst is supported on the metal honeycomb body according to any one of (1) to (8) above.

(11) A catalytic converter in which a catalyst is supported on a metal honeycomb body in the honeycomb unit according to (9) above.

(12) A method for manufacturing a honeycomb unit including a metal honeycomb body and an outer cylinder according to (1) above, in which a slurry-like base material containing a brazing material and a large number of metal pieces is applied to an end of the hollow part of the winding core. and a firing step of firing the honeycomb unit after the base material supplying step, and a predetermined portion of the honeycomb unit to be subjected to the firing step is filled with wax in advance. The predetermined portion includes a portion where the flat foil and the corrugated foil are to be joined, and a portion where the metal honeycomb body and the outer cylinder are to be joined, and in the base material supplying step, , where the total content of the metal pieces contained in the slurry base material is X% by mass and the total content of the brazing material is Y% by mass, X:Y is the ratio of X% by mass and Y% by mass. is included in the range of 3:7 to 9:1.

(13) The step of supplying the base material is a step of supplying the slurry base material to both ends of the hollow part of the winding core, and X:Y is within a range of 3:7 to 7:3. The method for manufacturing a honeycomb unit according to (12) above.

(14) After the firing step described in (12) or (13) above, a catalyst slurry inflow step of flowing a slurry containing a catalyst from an end in the axial direction of the honeycomb unit; and after the catalyst slurry inflow step. A method for manufacturing a catalytic converter, comprising: a catalyst supporting step of drying and firing the honeycomb unit to support a catalyst.

(15) The method for manufacturing a honeycomb unit according to (12) or (13) above, wherein a large number of through holes are formed in the flat foil and/or the corrugated foil.

(16) The method for manufacturing a catalytic converter according to (14) above, wherein the flat foil and/or the corrugated foil has a large number of through holes formed therein.

(17) The method for manufacturing a metal honeycomb body according to (1) above, in which a base material supplying step of supplying a slurry-like base material containing a brazing material and a large number of metal pieces from an end of the winding core hollow part. and, after the base material supply step, a firing step of firing the metal honeycomb body, and in the base material supply step, the total content of the metal pieces contained in the slurry base material is determined by X mass %, and when the total content of the brazing material is Y mass %, the ratio of X mass % to Y mass %, X:Y, is in the range of 3:7 to 9:1. Method for manufacturing metal honeycomb bodies.

(18) After the firing step described in (17) above, a catalyst slurry inflow step of flowing a slurry containing a catalyst from the axial end of the metal honeycomb body; and after the catalyst slurry inflow step, the metal A method for manufacturing a catalytic converter, comprising: carrying out a catalyst supporting step of drying and firing a honeycomb body to support a catalyst.

(19) The method for manufacturing a catalytic converter according to (18) above, wherein the flat foil and/or the corrugated foil has a large number of through holes formed therein.

According to the present invention, by disposing a porous plug at one end or both ends of the hollow core, exhaust gas can be prevented from escaping from the hollow core. Thereby, the steady-state purification performance of the metal honeycomb body can be improved.
Furthermore, since the plug is made of a porous material, the heat capacity of the metal honeycomb body can be lowered than when a dense plug is used. Thereby, the light-off performance of the metal honeycomb body can be improved.
Furthermore, the shape retention of the plug can be improved compared to the method of controlling the inflow of exhaust gas by processing metal foil.

FIG. 2 is a plan view of a catalytic converter. FIG. 3 is a cross-sectional view of a hollow part of a winding core in which porous plugs are provided at both ends. FIG. 2 is a developed view of the metal foil and an enlarged view of a part of the metal foil. FIG. 3 is a cross-sectional view of a porous plug. It is a cross-sectional photograph of the porous plug inside the hollow part of the winding core (X:Y=5:5). FIG. 3 is a cross-sectional view of a hollow part of the winding core with a porous plug disposed at one end.

Embodiments of the present invention will be described below.
The metal honeycomb body of the first embodiment is made of metal foil in which through holes are formed, and porous plugs are provided at both ends of the hollow part of the winding core.
The metal honeycomb body of the second embodiment is made of metal foil in which through holes are formed, and a porous plug is disposed at one end of the hollow part of the winding core.
The metal honeycomb body of the third embodiment is made of metal foil in which no through holes are formed, and porous plugs are provided at both ends of the hollow part of the winding core.
The metal honeycomb body of the fourth embodiment is made of metal foil in which no through holes are formed, and a porous plug is disposed at one end of the hollow part of the winding core.
Each embodiment will be described below.

(First embodiment)
FIG. 1 is a plan view of a catalytic converter according to an embodiment of the present invention, viewed from the axial direction. However, the porous plug disposed in the hollow part of the winding core is omitted from illustration. Note that the axial direction is also the direction in which exhaust gas flows toward the catalytic converter.
FIG. 2 is a cross-sectional view of the hollow part of the winding core of the catalytic converter, showing the arrangement position of the porous plug. FIG. 3 is a developed view of the metal foil that is the base of the flat foil and the corrugated foil, and an enlarged view of a part of the metal foil.

The catalytic converter 1 includes a metal honeycomb body 4 and an outer cylinder 5 on which a catalyst is supported. However, the outer cylinder 5 may be omitted. The metal honeycomb body 4 is constituted by a wound body in which a flat foil 2 and a corrugated foil 3 are layered and wound. By overlapping the flat foil 2 and the corrugated foil 3, a gas conduction path for conducting exhaust gas is formed. The catalytic converter 1 of this embodiment can be used as a purification device for purifying vehicle exhaust gas.

The flat foil 2 and corrugated foil 3 can be made of a metal foil made of a heat-resistant alloy. The thickness of the metal foil is preferably 20 μm or more. The thickness of the metal foil is preferably 100 μm or less, and more preferably 70 μm or less. By using a metal foil with such a thin thickness, the temperature rise rate of the metal honeycomb body 4 can be increased during exhaust gas purification, activating the catalyst and reducing the weight of the catalytic converter 1.

A large number of through holes 4a are formed in the metal foil serving as the base of the flat foil 2 and the corrugated foil 3. By forming a large number of through holes 4a in the flat foil 2 and the corrugated foil 3, the exhaust gas flowing into the metal honeycomb body 4 becomes a turbulent flow, and the steady-state purification performance can be improved. Furthermore, since the heat capacity of the metal honeycomb body 4 is reduced, the light-off performance can be improved.
However, a large number of through holes 4a may be formed only in the flat foil 2, or a large number of through holes 4a may be formed only in the corrugated foil 3.

If the diameter of the through hole 4a becomes too small, the through hole 4a may be blocked by the catalyst. Therefore, the diameter of the through hole 4a is preferably 0.2 mm or more.
If the diameter of the through-holes 4a becomes too large, there is a risk that the steady-state purification performance will be lower than that of a metal honeycomb body without through-holes. Therefore, the diameter of the through hole 4a is preferably 8 mm or less.
In order to achieve a low heat capacity of the metal honeycomb body 4, the aperture ratio of the through holes 4a is preferably 20% or more. In order to achieve durability of the metal honeycomb body 4, the aperture ratio of the through holes 4a is preferably 60% or less.

It is desirable that the predetermined region on the gas inlet side of the metal honeycomb body 4 (hereinafter also referred to as the non-opening part on the gas inlet side) be a non-opening part without the through hole 4a. It is desirable that the non-opening portion on the gas inlet side be 1 mm or more from the end on the gas inlet side. Thereby, the strength of the foil can be maintained and a sufficient bonding area between the porous plug and the foil can be secured.
Since the plug of this embodiment is porous, if the entire plug is bonded to a region with an opening, the bonding area may be reduced and the bonding strength of the porous plug may be reduced. This problem can be eliminated by bonding at least a portion of the porous plug to the non-opening portion of the metal foil.
Note that it is desirable that the non-opening portion on the gas inlet side be 10 mm or less from the end on the gas inlet side.

It is desirable that a predetermined region on the gas outlet side of the metal honeycomb body 4 (hereinafter also referred to as a non-opening part on the gas outlet side) be a non-opening part without the through hole 4a. It is desirable that the non-opening portion on the gas outlet side be 1 mm or more from the end on the gas inlet side. The reason for this is the same as that for the non-opening portion on the gas inlet side, so the explanation will be omitted.
Note that it is desirable that the non-opening portion on the gas outlet side be 10 mm or less from the end on the gas outlet side.

As illustrated in FIG. 3, the through holes 4a of this embodiment are arranged in a staggered manner with respect to the metal foil. Here, draw a triangle connecting the centers of three mutually adjacent through holes 4a with a line, and the area inside the triangle is the "total area", and the area of the overlapping part of the triangle shown in black and the through hole 4a is " When defined as "pore area", the ratio of "pore area" to "total area" can be defined as "opening ratio". Since the method of calculating the aperture ratio is common knowledge in the art, the above explanation will be omitted.
In addition, although the shape of the through-hole 4a was circular in this embodiment, it may be other shapes (for example, an ellipse, a polygon, etc.). Further, the arrangement form of the through holes 4a is not limited to a staggered arrangement, but may be arranged in another arrangement form (for example, a lattice arrangement).

The lower limit of the plate width of the metal foil is preferably three times the diameter of the winding core hollow part 6, which will be described later. The upper limit of the width of the metal foil is preferably 500 mm. The size of the metal foil can be changed as appropriate depending on the use of the catalytic converter 1. The corrugated foil 3 can be manufactured by corrugating metal foil, for example.

Here, for example, various types of heat-resistant stainless steel containing Al in the alloy composition can be used for the metal foil. As the stainless steel, ferritic stainless steel (in other words, Fe-20Cr-5Al alloy) consisting of 20% by mass of Cr, 5% by mass of Al, and the balance being Fe and inevitable impurities can be used. However, other stainless steels (for example, stainless steel containing 15-25% by mass of Cr and 2-8% by mass of Al) can also be used.

A brazing material can be used for joining the flat foil 2 and the corrugated foil 3 and joining the metal honeycomb body 4 and the outer cylinder 5. For example, a Ni-based brazing material with high heat resistance can be used as the brazing material. The brazing material may be foil brazing or powder brazing.

The catalyst can be supported on the metal foil by applying a predetermined wash coat liquid to the surface of the metal foil of the metal honeycomb body 4, drying and firing it. The method for applying the wash coat liquid will be described later.

For the outer cylinder 5, a ferritic stainless steel containing about 13% by mass or more and 20% by mass or less of Cr, such as SUS436L or SUS430, can be used.
The lower limit of the wall thickness of the outer tube 5 is preferably 0.5 mm. The upper limit of the wall thickness of the outer tube 5 is preferably 3 mm.
The lower limit of the cell density of the metal honeycomb body 4 is preferably 15.5 cells per square centimeter (in other words, 100 cells per square inch). The upper limit of the cell density of the metal honeycomb body 4 is preferably 93 cells per square centimeter (in other words, 600 cells per square inch).

A core hollow part 6 is formed in the center of the metal honeycomb body 4 and extends in a cylindrical shape in the axial direction. Porous plugs 30 are arranged at both ends of the winding core hollow part 6. FIG. 4 schematically shows a cross section of the porous plug 30.
A plug slurry liquid (corresponding to a slurry base material) is prepared by mixing a large number of metal pieces 31 and fragmented or powdered brazing material in a liquid with appropriate viscosity, and this plug slurry liquid is wound around the core. The porous plugs 30 can be placed at both ends of the winding core hollow part 6 by injecting the porous plugs from one end and the other end of the hollow part 6 and then drying and firing. Therefore, the porous plug 30 has a structure in which a large number of metal pieces 31 are joined with brazing material. Since the porous plug 30 has a large number of voids formed therein, the heat capacity is lower than that of a conventional dense plug, and the light-off performance can be improved.

The inventors believe that the mechanism by which voids are formed is as follows. A plug slurry liquid containing metal pieces 31 and brazing material is injected into the winding core hollow part 6, and then the liquid is removed by drying. Further, during subsequent firing, the brazing material melts, and the molten brazing material permeates into the gaps between the metal pieces, thereby forming voids.

The dotted lines in FIG. 4 indicate the positions of both ends of the porous plug 30, and the volume ratio of voids in the region between these dotted lines is the porosity of the porous plug 30. Note that FIG. 4 illustrates only the porous plug 30 on one end side.
In other words, a region surrounded by a surface along the upper and lower end surfaces of the porous plug 30 (the surface indicated by the dotted line in FIG. 4) and the inner surface of the winding core hollow part 6 is defined, and the area occupied by the void with respect to the volume of the region is defined. The volume ratio can be referred to as "porosity." The upper and lower end surfaces of the porous plug 30 define one end and the other end in the longitudinal direction of the winding core hollow part 6 in the solid part of the porous plug 30 excluding voids, and the surface passing through the one end and the other end are defined as The surfaces through which it passes can be referred to as "upper and lower end surfaces."
For example, by taking a plurality of X-ray CT images of the porous plug 30 as an imaging target, binarizing these CT cross-sectional images and separating them into a solid part and a void part, and calculating the area ratio of the voids. , the porosity of the porous plug 30 can be calculated.
Specifically, the arithmetic mean value of the area ratio of voids in each CT cross-sectional image can be set as the porosity of the porous plug 30.

The porosity of the porous plug 30 is preferably 7% or more. By increasing the porosity of the porous plug 30 to 7% or more, the heat capacity of the porous plug 30 is sufficiently reduced, and the light-off performance of the metal honeycomb body 4 can be improved.

The porosity of the porous plug 30 is preferably 85% or less. When the metal pieces 31 and the brazing material are used as raw materials, if the porosity becomes excessively high, solid-phase bonding between the metal pieces without the brazing material becomes dominant, so that the strength of the porous plug 30 itself (i.e., The shape retention of the plug will not be maintained.
Further, if the porosity of the porous plug 30 is suppressed to 85% or less, exhaust gas can be effectively prevented from escaping from the winding core hollow part 6. That is, the metal foils (the flat foil 2 and the corrugated foil 3) of this embodiment are formed with a large number of through holes 4a, and the pressure loss of the metal honeycomb body 4 becomes large, so that exhaust gas escapes from the winding core hollow part 6. easy. This tendency becomes particularly noticeable when the flow rate of exhaust gas is high. In this embodiment, since both ends of the winding core hollow part 6 are closed by the porous plugs 30, exhaust gas can be effectively prevented from escaping from the winding core hollow part 6. Thereby, the steady-state purification performance of the metal honeycomb body 4 can be improved.

When the diameter of the winding core hollow part 6 is defined as D, the axial length of the porous plug 30 is preferably D or more. By setting the axial length of the porous plug 30 to be greater than or equal to D, a sufficient bonding area of the porous plug 30 to the winding core hollow part 6 is ensured, so that the porous plug 30 can be removed from the winding core hollow part 6. It can prevent it from falling off.
The axial length of the porous plug 30 is preferably 3D or less. By setting the axial length of the porous plug 30 to 3D or less, the heat capacity reduction effect of the porous plug 30 can be more effectively exhibited.

It is desirable to use the same brazing material as the brazing material used to join the flat foil 2 and the corrugated foil 3 as the brazing material of the porous plug 30. For example, when a Ni-based brazing material is used as the bonding material for the flat foil 2 and the corrugated foil 3, it is desirable to use the same Ni-based brazing material as the brazing material for the porous plug 30. This makes it possible to equalize the heat resistance and thermal expansion of the joint between the flat foil 2 and the corrugated foil 3 and the joint between the metal piece 31. Examples of Ni-based brazing materials include BNi-1 to BNi-7 specified in "JISZ 3265," BNi-5a, BNi-8, and BNi published by AWS (American Welding Society). -9, BNi-10, BNi-11, BNi-12, BNi-13, etc. can be used. However, the types of brazing materials may be different as long as the coefficients of thermal expansion of the brazing materials are relatively similar.

It is desirable to use the same metal as the flat foil 2 and the corrugated foil 3 for the metal piece 31. Thereby, the heat resistance and thermal expansion properties of the metal piece 31, the flat foil 2, and the corrugated foil 3 can be made equal. However, the types of metals may be different as long as their coefficients of thermal expansion are relatively similar.

The shape of the metal piece 31 is not particularly limited, but may be, for example, a disc shape, a spherical shape, a triangular pyramid shape, a cubic shape, etc. Alternatively, the porous plug 30 may be formed by mixing metal pieces 31 having different shapes. However, if the metal piece 31 is formed into a disk shape, the aspect ratio becomes large and voids are likely to be formed. Therefore, it is preferable to use a disk-shaped metal piece 31.

Next, a method for disposing the porous plug 30 in the winding core hollow part 6 will be specifically explained. A plug slurry liquid (corresponding to a slurry base material) is prepared by mixing a large number of metal pieces 31 and a piece-like or powdered brazing material in a liquid having an appropriate viscosity. When the total content of the metal pieces 31 in the plug slurry liquid is X% by mass and the total content of the brazing metal is Y% by mass, the ratio of X% by mass to Y% by mass, X:Y, is 3: It is in the range of 7 to 9:1. When the conditions of this compounding ratio are expressed as a fraction, X/Y is 3/7 or more and 9/1 or less.
If X/Y becomes too small, it becomes impossible to maintain the shape as a plug. In other words, if the amount of brazing material is excessively large, the brazing material will flow down during firing, making it impossible to obtain a plug-shaped fired body.

If X/Y becomes too large, the strength of the porous plug 30 itself will decrease. In other words, due to the lack of brazing material, solid-phase bonding between the metal pieces without using the brazing material becomes dominant, and the brazing strength between adjacent metal pieces 31 decreases, so that the plug form cannot be maintained. I can't.

A preferable lower limit of X:Y is 4:6. In other words, the preferable lower limit of X/Y is 4/6. By setting X/Y to 4/6 or more, the porosity of the porous plug 30 increases, and the light-off performance of the catalytic converter 1 improves. That is, since the amount of brazing material filling the voids is reduced, the porosity of the porous plug 30 can be increased.
A preferable upper limit of X:Y is 7:3. In other words, the preferable upper limit of X/Y is 7/3. By setting X/Y to 7/3 or less, the brazing strength of adjacent metal pieces 31 is improved, and the shape retention of the plug can be further improved.

Here, FIG. 5 is a photograph of a porous plug when X:Y is 5:5, and as is clear from this photograph, the plug shape is maintained.

A predetermined amount of the prepared plug slurry liquid is injected into the winding core hollow part 6 from both ends of the winding core hollow part 6 and dried.

After the plug slurry liquid is injected and dried, the metal honeycomb body 4 is fired at a temperature of about 1200° C. in a vacuum atmosphere (corresponding to the "firing process" described later). When the metal honeycomb body 4 is fired, the adjacent metal pieces 31 are brazed together with the molten brazing material. Further, since the molten brazing material also adheres to the inner surface of the hollow core 6, the porous plug 30 can be held at the planned placement position at both ends of the hollow core 6.

Next, a method for manufacturing the honeycomb unit and the catalytic converter will be described.
The manufacturing process of the honeycomb unit can be divided into a preparation process before the firing process and a firing process. The preparation process includes a process A of disposing a brazing material on the intended joining portions of the flat foil 2 and the corrugated foil 3, a process B of disposing a brazing material on the intended joining portions of the metal honeycomb body 4 and the outer tube 5, and a process C of injecting a plug slurry liquid into the hollow portion 6 of the winding core. There are no particular limitations on the means of disposing the brazing material, and the disposing means may be, for example, the application of a powdered brazing material or the temporary fixing with foil brazing.

Step A may be performed when the flat foil 2 and the corrugated foil 3 are wound around a predetermined axis, or may be performed after the flat foil 2 and the corrugated foil 3 are wound. When carried out after winding, for example, step A can be carried out by spraying brazing material from above the metal honeycomb body 4 toward the portion to be joined.

Step B may be performed after step A. For example, after carrying out step A, a strip-shaped solder foil is wrapped around the part of the metal honeycomb body 4 to be joined, and after the metal honeycomb body 4 wrapped with the solder foil is inserted into the outer cylinder 5, the outer cylinder 5 is contracted. Step B can be carried out by pressing it against the metal honeycomb body 4 around which the solder foil is wrapped. Compression means for compressing the outer tube 5 radially inward can be used as the diameter reduction means. Further, step B is not limited to the diameter reducing means. For example, step B may be realized by press-fitting the metal honeycomb body 4 wrapped with solder foil into the outer cylinder 5.
However, step B may be implemented before step A. For example, after manufacturing the metal honeycomb body 4 by winding the flat foil 2 and the corrugated foil 3 around a predetermined axis, the foil solder is wrapped around the metal honeycomb body 4 and process B is performed, and after the process B is performed, the solder metal is sprinkled and the metal honeycomb body 4 is manufactured. You may also implement A.

The order of step C is not particularly limited. As shown in the Examples described below, it may be carried out after Step A and Step B, or may be carried out before Step A and/or Step B. However, since step C is a step of injecting the plug slurry liquid into the winding core hollow part 6, it needs to be carried out after at least the flat foil 2 and the corrugated foil 3 are wound around a predetermined axis.

The description of the firing process performed after the preparation process will not be repeated. By performing the firing process after steps A to C, the manufacturing and installation of the porous plug 30, the joining process of the flat foil 2 and the corrugated foil 3, and the joining process of the metal honeycomb body 4 and the outer cylinder 5 can be performed. Can be carried out simultaneously.

Next, a method for manufacturing a catalytic converter will be described in detail.
After manufacturing the honeycomb unit (in other words, after performing the firing process), the metal honeycomb body 4 is made to support a catalyst. As a method for supporting the catalyst, for example, an immersion method or a suction method can be used.
The immersion method is a method in which the metal honeycomb body 4 joined to the outer cylinder 5, that is, the above-mentioned honeycomb unit, is immersed in a wash coat liquid, and a catalyst is applied to the metal foil constituting the metal honeycomb body 4 ("catalyst"). slurry inlet step). As the washcoat liquid, for example, a slurry liquid obtained by stirring γ alumina powder, lanthanum oxide, zirconium oxide, and cerium oxide in an aqueous solution of palladium nitrate can be used.

Here, if the porous plug 30 is placed only on one end side of the hollow portion 6 of the winding core, the washcoat liquid containing the catalyst will flow in from the other end side of the hollow portion 6 of the winding core. This means that there is a risk of excess catalyst accumulating inside the hollow portion 6 of the winding core. To solve this problem, it is necessary to drill a hole through the porous plug 30, which increases the number of processing steps.

According to this embodiment, since both ends of the core hollow part 6 are closed by the porous plugs 30, when the honeycomb unit is immersed in the washcoat liquid, the washcoat liquid is inside the winding core hollow part 6. It is possible to prevent the inflow of This reduces the amount of catalyst used, thereby reducing costs. Furthermore, the step of forming a through hole in the porous plug 30 can be omitted.

In the suction method, a wash coat liquid containing a catalyst is sucked from the axial direction of the metal honeycomb body 4, and the catalyst is applied to the metal foil constituting the metal honeycomb body 4 (corresponding to the "catalyst slurry inflow step"). ). In the suction method as well, as explained in the immersion method, by closing both ends of the hollow core 6 with the porous plugs 30, it is possible to prevent the washcoat liquid from flowing into the hollow core 6.
After applying the wash coat liquid to the metal foil of the metal honeycomb body 4, the applied catalyst can be supported on the metal foil by drying and firing (corresponding to a "catalyst supporting step"). The firing conditions are appropriately set depending on the inner diameter of the cells, the axial length of the metal honeycomb body 4, the type of washcoat liquid, etc. For example, the firing temperature can be set to 400 to 800°C, and the firing time can be set to 1 to 6 hours. can. After the catalyst is introduced, the catalyst can be supported by drying and firing.

Furthermore, in the case where the catalytic converter 1 does not have the outer cylinder 5, the catalytic converter may be formed by applying a wash coat liquid to the metal honeycomb body 4 by the method described above, drying and firing.

Here, if the porosity of the porous plug 30 is suppressed to 70% or less, it is possible to effectively prevent the washcoat liquid from flowing into the winding core hollow part 6.

In addition, when the porous plugs 30 are arranged at both ends of the winding core hollow part 6, one axial end of the metal honeycomb body 4 may be arranged facing the exhaust gas upstream side, or the other axial end may be arranged so as to face the exhaust gas upstream side. It may be arranged toward the exhaust gas upstream side.

(Second embodiment)
FIG. 6 is a sectional view of the winding core hollow part in the catalytic converter of this embodiment, and shows the arrangement position of the porous plug. The porous plug 30 of this embodiment is arranged only at one end (preferably the gas inlet side end) of the winding core hollow part 6, and the porous plug 30 is arranged at both ends of the winding core hollow part 6. This is different from the first embodiment. Since the catalytic converter of this embodiment has the same configuration as the catalytic converter of the first embodiment except for the arrangement position of the porous plug 30, only the porous plug 30 will be described.

A slurry liquid is prepared by mixing a large number of metal pieces 31 and a brazing material in a liquid with appropriate viscosity, and this slurry liquid is injected into one end of the winding core hollow part 6, and then dried and fired to form the winding core. A porous plug 30 can be disposed at one end of the hollow portion 6.

The preferred porosity of the porous plug 30 is the same as in the first embodiment, so detailed explanation will be omitted. The preferred axial length of the porous plug 30 is the same as that in the first embodiment, so a detailed explanation will be omitted.

The material of the porous plug 30 and the shape of the metal piece 31 are also the same as in the first embodiment, so detailed explanations will be omitted.

The porous plug 30 is not disposed at the other end of the winding core hollow part 6 in this embodiment. Therefore, when applying the washcoat liquid to the metal honeycomb body 4, the washcoat liquid flows from the other end of the winding core hollow part 6. Therefore, a through hole may be formed in the porous plug 30, and the wash coat liquid that has flowed into the winding core hollow portion 6 may be discharged from the through hole. Thereby, it is possible to prevent excess catalyst from accumulating in the winding core hollow part 6.
Note that the through hole may be formed by drilling a hole in the heat-treated porous plug 30 using a drill or the like. The through-hole escape hole is also described in paragraph 0023 of Patent Document 2, so a detailed explanation will be omitted. Note that the "through hole 10" in Patent Document 2 corresponds to the "through hole" in this specification.

In the first embodiment, the upper limit of the porosity of the porous plug 30 was set to 70% as a preferable condition in order to prevent the washcoat liquid from flowing into the hollow part 6 of the winding core. The washcoat liquid is allowed to flow into the porous plug 6, and the washcoat liquid is discharged by forming through holes in the porous plug 30. Therefore, the description of the first embodiment is not referred to regarding setting the upper limit of the porosity of the porous plug 30 to 70%.

The composition of the plug slurry used to manufacture the porous plug 30 is the same as that in the first embodiment, and therefore a detailed description thereof will be omitted. The method of supporting the catalyst has also been described in the first embodiment, and therefore a detailed description thereof will be omitted.
Also in the second embodiment, the porous plug 30 may be disposed facing the exhaust gas inlet side, or the porous plug 30 may be disposed facing the exhaust gas outlet side.

(Third embodiment)
The catalytic converter of this embodiment is the same as the catalytic converter of the first embodiment in that porous plugs 30 are provided at both ends of the winding core hollow part 6. However, this embodiment differs from the catalytic converter of the first embodiment in that through-holes 4a are not formed in the flat foil 2 and the corrugated foil 3. Except for such differences, the description of the first embodiment is incorporated into this embodiment.

Since the through holes 4a are not formed in the flat foil 2 and the corrugated foil 3 of this embodiment, a catalytic converter with low pressure loss can be provided.

(Fourth embodiment)
The catalytic converter of this embodiment is the same as the catalytic converter of the second embodiment in that a porous plug 30 is disposed at one end of the winding core hollow part 6. However, this embodiment differs from the catalytic converter of the second embodiment in that through-holes 4a are not formed in the flat foil 2 and the corrugated foil 3. Except for such differences, the description of the second embodiment is incorporated into this embodiment.

In this embodiment, the flat foil 2 and corrugated foil 3 do not have through holes 4a formed, so a catalytic converter with low pressure loss can be provided.

Next, the present invention will be specifically described with reference to Examples.
(First example)
The first example corresponds to the first embodiment.
A plurality of samples with different mixing ratios of metal pieces and brazing metal were prepared, and the shape retention of the plug, light-off performance, catalyst inflow prevention effect, and steady-state purification performance were evaluated.
A metal honeycomb body with a hollow core was manufactured by winding corrugated foil and flat foil in a stacked state. For the corrugated and flat metal foils (foil thickness: 50 μm), ferritic stainless steel containing 20% by mass of Cr, 5% by mass of Al, and the balance Fe and inevitable impurities was used. Also, a metal foil with a large number of through holes was used. The through hole was circular with a diameter of 0.9 mm. The through holes were arranged in a staggered manner. The aperture ratio was 40%. Note that the aperture ratio was calculated by the method described in the embodiment. Further, non-opening portions with a width of 5 mm were provided at the ends of the gas inlet side and the gas outlet side. The diameter, length, cell density, and diameter of the core hollow part of the metal honeycomb body were 33 mm, 60 mm, 300 cpsi, and 5 mm, respectively. BNi-5 (see JISZ 3265) was used as the bonding material (brazing material) for the corrugated foil and flat foil. The process of disposing the bonding material for the corrugated foil and the flat foil was carried out before the plug slurry liquid was injected.

After wrapping a foil-like brazing material around the part of the outer peripheral surface of the metal honeycomb body to be joined, the metal honeycomb body was inserted into an outer cylinder made of SUS436L with a thickness of 1.5 mm and a length of 60 mm, and a plug was formed under the following conditions. Injection treatment and firing treatment of slurry liquid were carried out.

The metal pieces used for the porous plugs were made of metal with the same composition as the corrugated foil and flat foil. The brazing material was a powdered brazing material with the same composition as the brazing material used to join the corrugated foil and flat foil. The metal pieces were disk-shaped with a diameter of 0.9 mm and a thickness of 0.05 mm. A plug slurry liquid containing the metal pieces and brazing material was poured into both ends of the hollow part of the winding core of the metal honeycomb body, and then dried at 200°C in air. After drying, the honeycomb unit was fired at 1200°C in a vacuum to provide porous plugs with an axial length of 10 mm at both ends of the hollow part of the winding core. As described above, since the diameter of the hollow part of the winding core is 5 mm, the diameter of the porous plugs is also 5 mm.
Thereafter, a catalyst was applied to the metal foil by a dipping method using a slurry liquid prepared by stirring gamma alumina powder, lanthanum oxide, zirconium oxide, and cerium oxide in an aqueous solution of palladium nitrate. The catalyst was then dried at 200°C and then fired in air at 500°C for 1 hour to produce a catalytic converter.

The mixing ratio (X:Y) of the metal piece and brazing material is 5:5 in Example 1, 3:7 in Example 2, 4:6 in Example 3, 7:3 in Example 4, and 7:3 in Example 5. was 9:1, Comparative Example 1 was 1:9, and Comparative Example 2 was 9.5:0.5.
Three samples were prepared for each of Examples 1 to 5 and Comparative Example 1, and the porosity was measured. However, in Comparative Example 1, the porosity was not measured because the blending ratio of metal pieces was too low and none of the samples took the form of a plug. As described in the embodiment, the porosity is the arithmetic mean value of the porosity obtained by acquiring 10 X-ray CT images of the porous plug, binarizing each X-ray CT image, and performing image analysis. And so. In this example, only the porosity of the porous plug disposed at one end was measured.

In Comparative Example 3, a dense plug (hereinafter also referred to as an N plug) was provided in place of the porous plug. The same material as the metal piece of the porous plug was used for the N plug. The axial length of the N plug was 10 mm, similar to the porous plug of the example. In Comparative Example 4, neither the porous plug nor the N plug was provided. In Comparative Example 5, a conical jig was pushed into the overlapping part of the flat foil and the corrugated foil extending into the hollow part of the winding core to expand it, thereby providing a regulating part for regulating the inflow of exhaust gas (that is, the regulation part that regulates the inflow of exhaust gas was provided). Center shape processing in Reference 3).

The shape retention of the plug was evaluated by pushing in the porous plug 30 disposed on one end side with a rod from the upper end surface and by the change in the shape of the plug after unloading. The size of the rod was φ4 mm, the pushing distance of the rod was 20 mm, and the pushing speed of the rod was 1.0 mm/sec. Here, if the metal pieces constituting the porous plug are firmly joined by a brazing material, the porous plug will not be deformed and can maintain its original shape even when a load is applied. On the other hand, porous plugs with weak connections between metal pieces change their shape under load. The shape change affects the sealing range of the porous plug. If the bond between the metal pieces is weak, the porous plug will fall apart when using the metal honeycomb body. If it falls apart, the plug loses its original function of suppressing the inflow of gas into the hollow part of the winding core (in other words, preventing gas from escaping).

Therefore, in this example, if the shape after the load test is the same as the original shape, it is evaluated by AAA as having very good shape retention, and if the axial reduction is within 1 mm, shape retention is evaluated. The properties are evaluated as AA and the reduction exceeds 1 mm, but if the metal pieces can be evaluated to be bonded to each other and the sealed area is sealed, the shape retention is somewhat good. If the shape change was large and it was determined that the sealed portion could not be properly sealed, the shape retention was judged to be poor and the shape was evaluated as B.

The metal honeycomb body was cut in the axial direction at the position of the hollow part of the winding core, and the degree of catalyst infiltration was visually confirmed to evaluate the catalyst inflow prevention effect. If the catalyst had not infiltrated into the porous plugs, the catalyst inflow prevention effect was deemed very good and rated as AAA. If the catalyst infiltration into the porous plugs stopped midway, the inflow prevention effect was deemed good and rated as AA. If catalyst infiltration into the hollow part of the winding core was confirmed in only some of the tested samples, the catalyst inflow prevention effect was deemed somewhat good and rated as A. If catalyst infiltration into the hollow part of the winding core was confirmed in all of the tested samples, the catalyst inflow prevention effect was deemed poor and rated as B.

The light-off performance was measured by flowing a simulated gas through a metal honeycomb body under the condition of SV (space velocity): 100,000h ^-1 , gradually increasing the gas temperature from room temperature, and calculating the HC conversion rate (%) at each temperature. was measured and evaluated by the time (τ50) when the conversion rate reached 50% from the conversion rate-temperature curve. When τ50 was 9 seconds or less, it was evaluated as AAA, when it was 11 seconds or less, it was evaluated as AA, when it was 13 seconds or less, it was evaluated as A, and when it exceeded 13 seconds, it was evaluated as B. In addition, based on the temperature (T80) when the conversion rate reaches 80% from the conversion rate-temperature curve, the steady purification performance is determined as AA when T80 is 230℃ or less, A when it is 240℃ or less, and B when it is over 240℃. evaluated. The simulated gases include HC (propane, C ₃ H ₆ ): 550 ppm (1650 ppm C), NO: 500 ppm, CO: 0.5%, O ₂ : 1.5%, H ₂ O: 10%, the balance being N ₂ A simulated gas (simulated diesel exhaust gas) was used.

In Examples 1 to 5, the shape retention of the plug was improved compared to Comparative Example 5 in which center shape processing was adopted as a regulating means. In Comparative Example 2, the plug shape retention was evaluated as B because the amount of brazing material was too small. Furthermore, it has been found that by setting X:Y to 7:3 or less, in other words, by setting X/Y to 7/3 or less, a desired bonding strength can be obtained and the shape retention of the plug can be improved. Examples 1 to 5 had better light-off performance than Comparative Example 3, which employed an N plug. It was found that by setting X:Y to 4:6 or more, in other words, by setting X/Y to 4/6 or more, the porosity of the porous plug 30 was increased and the light-off performance was further improved.
It has been found that the effect of preventing catalyst inflow can be obtained by setting X:Y to 7:3 or less, in other words, by setting X/Y to 7/3 or less.
In addition, Examples 1 to 5 had better steady-state purification performance than Comparative Example 4, and the original purpose of the plug (improving purification performance by regulating the inflow of exhaust gas into the hollow part of the winding core) was also maintained.

(Second example)
The second example corresponds to the second embodiment.
The metal honeycomb body was the same as in the first example. The metal piece and brazing material were the same as in the first example.
A porous plug with an axial length of 10 mm was disposed only on one end side (gas inlet side) of the hollow part of the winding core, and as in the first embodiment, plug shape retention, light-off performance, and constant purification performance were achieved. was evaluated. The evaluation method was the same as in the first example. Note that the effect of preventing the inflow of the catalyst was not evaluated. The conditions other than the porous plug were the same as in the first example.
However, in Comparative Example 7, metal foil without through holes was used and the hollow part of the winding core was not sealed.

The mixing ratio (X:Y) of the metal piece and brazing material was 5:5 in Example 6, 3:7 in Example 7, 4:6 in Example 8, 7:3 in Example 9, and 7:3 in Example 10. The ratio was 9:1.

In Comparative Example 6, the N plug of Comparative Example 3 was disposed only on one end side (gas inlet side) of the hollow part of the winding core.

In Examples 6 to 10, the shape retention of the plug was improved compared to Comparative Example 5 (see Table 1), which employed central shape processing as the restricting means. It was also found that a desired bonding strength was obtained and the shape retention of the plug was improved by setting X:Y to 7:3 or less, in other words, X/Y to 7/3 or less. In Examples 6 to 10, the light-off performance was improved compared to Comparative Example 6, which employed an N plug. It was found that by setting X:Y to 4:6 or more, in other words, X/Y to 4/6 or more, the porosity of the porous plug 30 was increased and the light-off performance was further improved.
Moreover, Examples 6 to 10 were superior in steady-state purification performance to Comparative Example 4 (see Table 1), and the original purpose of the plug (to regulate the inflow of exhaust gas into the hollow part of the winding core and improve purification performance) was also achieved.
Furthermore, Examples 6 to 10 had better steady-state purification performance than Comparative Example 7 (no through-holes, no sealing), and the light-off performance was equal to or better. Therefore, it was found that the problem of concern caused by forming a large number of through-holes in the metal foil (decrease in steady-state purification performance due to gas concentration in the hollow part of the winding core) can be solved by using porous plugs. It was also found that the problem of concern caused by providing plugs in the hollow part of the winding core (decrease in light-off performance) can be solved by making the plugs porous.

The present inventors disposed the porous plug of Example 8 in the hollow part of the shaft core of a metal honeycomb body in which the diameter of the through-hole of the metal foil was 8 mm, and while changing the aperture ratio, the steady-state purification performance was improved. A separate test was also conducted to investigate. Regardless of whether the aperture ratio was 20%, 30%, 40%, 50%, or 60%, the steady-state purification performance was evaluated as A or AA.
In addition, the porous plug of Example 8 was arranged in the hollow part of the shaft core of a metal honeycomb body with an open area ratio of 20%, and a separate test was conducted to examine the steady-state purification performance while changing the diameter of the through hole. . Regardless of whether the diameter of the through hole was 0.5 mm, 2 mm, or 4 mm, the steady-state purification performance was evaluated as AA.

(Third example)
The third example corresponds to the third embodiment.
A metal honeycomb body with no through holes formed in the metal foil was used. The other configurations of the metal honeycomb body were the same as in the first example. The metal piece and brazing material were the same as in the first example.

The mixing ratio (X:Y) of the metal pieces and brazing material is 5:5 in Example 11, 3:7 in Example 12, 4:6 in Example 13, 7:3 in Example 14, and 7:3 in Example 15. was 9:1, Comparative Example 8 was 1:9, and Comparative Example 9 was 9.5:0.5. Three samples were prepared for each of Examples 11 to 15 and Comparative Example 8, and the porosity was measured. However, in Comparative Example 8, the proportion of metal pieces was too low and none of the samples took the form of a plug, so the porosity was not measured. The porosity was measured in the same manner as in the first example.

In Comparative Example 10, an N plug was provided in place of the porous plug. The same material as the metal piece of the porous plug was used for the N plug. The axial length of the N plug was 10 mm, similar to the porous plug of the example. In Comparative Example 11, neither the porous plug nor the N plug was provided. In Comparative Example 12, the regulating portion (center shape processing) of Comparative Example 5 was provided.

Porous plugs with an axial length of 10 mm were placed at both ends of the hollow part of the winding core, and plug shape retention, light-off performance, catalyst inflow prevention effect, and steady purification performance were evaluated. Additionally, pressure loss was also evaluated as reference information.

The shape maintenance of the plug and the effect of preventing catalyst inflow were evaluated in the same manner as in the first example.

The light-off performance was measured by flowing a simulated gas through a metal honeycomb body under the condition of SV (space velocity): 100,000h ^-1 , gradually increasing the gas temperature from room temperature, and calculating the HC conversion rate (%) at each temperature. was measured and evaluated by the time (τ50) when the conversion rate reached 50% from the conversion rate-temperature curve. When τ50 was 12 seconds or less, it was evaluated as AAA, when it was 14 seconds or less, it was evaluated as AA, when it was 16 seconds or less, it was evaluated as A, and when it exceeded 16 seconds, it was evaluated as B.
In addition, based on the temperature (T80) when the conversion rate reaches 80% from the conversion rate-temperature curve, the steady purification performance is determined as AA when T80 is 240°C or less, A when it is 250°C or less, and B when it is over 250°C. evaluated. The simulated gases include HC (propane, C ₃ H ₆ ): 550 ppm (1650 ppm C), NO: 500 ppm, CO: 0.5%, O ₂ : 1.5%, H ₂ O: 10%, the balance being N ₂ A simulated gas (simulated diesel exhaust gas) was used.

The pressure loss was evaluated by flowing dry N ₂ gas at 25° C. into the metal honeycomb body at a flow rate of 0.12 Nm ³ /min and measuring the pressure difference before and after the metal honeycomb body. Compared to Comparative Example 11 (no sealing), if the difference was within ±1%, the pressure loss was considered to be low and evaluated as A; if the difference exceeded 1%, the pressure loss was considered to be large and evaluated as B.

Examples 11 to 15 showed improved plug shape retention compared to Comparative Example 12, which employed central shape processing as the regulating means. Comparative Example 9 was rated a B for plug shape retention because the amount of brazing material was insufficient. It was also found that the desired joint strength was obtained and the plug shape retention was improved by setting X:Y to 7:3 or less, in other words, X/Y to 7/3 or less. Examples 11 to 15 showed improved light-off performance compared to Comparative Example 10, which employed an N plug.
It was found that by setting X:Y to 4:6 or more, in other words, X/Y to 4/6 or more, the porosity of the porous plug 30 was increased, and the light-off performance was further improved.
It was found that the catalyst inflow prevention effect can be obtained by setting X:Y to 7:3 or less, in other words, by setting X/Y to 7/3 or less.
Moreover, Examples 11 to 15 were superior to Comparative Example 11 in steady-state purification performance and had pressure loss equivalent to that of Comparative Example 11, and thus were able to achieve the original purpose of the plug (to regulate the inflow of exhaust gas into the hollow part of the winding core and improve the purification performance without increasing the pressure loss).

(Fourth example)
The fourth example corresponds to the fourth embodiment.
A metal honeycomb body with no through holes formed in the metal foil was used. The other configurations of the metal honeycomb body were the same as in the first example. The metal piece and brazing material were the same as in the first example.
A porous plug having an axial length of 10 mm was disposed at the gas inlet end of the hollow part of the winding core, and plug shape retention, light-off performance, steady purification performance, and pressure loss were evaluated. However, in Example 21, a porous plug was provided at the gas outlet end.

The compounding ratio (X:Y) of the metal pieces and brazing material was 5:5 for Example 16, 3:7 for Example 17, 4:6 for Example 18, 7:3 for Examples 19 and 21, 9:1 for Example 20, 1:9 for Comparative Example 13, and 9.5:0.5 for Comparative Example 14. For each of Examples 16-21 and Comparative Example 13, three samples were prepared and the porosity was measured. However, for Comparative Example 13, the compounding ratio of the metal pieces was too low and none of the samples were in a plug shape, so the porosity was not measured. The porosity was measured in the same manner as in the first example.

In Comparative Example 15, an N plug was provided in place of the porous plug. The same material as the metal piece of the porous plug was used for the N plug. The axial length of the N plug was 10 mm, similar to the porous plug of the example. In Comparative Example 16, neither the porous plug nor the N plug was provided. In Comparative Example 17, the regulating portion (center shape processing) of Comparative Example 5 was provided.

The shape retention of the plug was evaluated using the same method as in the first example.
Light-off performance, steady-state purification performance, and pressure loss were evaluated using the same methods as in the third example.

In Examples 16 to 20, the shape retention of the plug was improved compared to Comparative Example 17 in which center shape processing was adopted as a regulating means. In Comparative Example 14, the plug shape retention was evaluated as B because the amount of brazing material was too small. Furthermore, it has been found that by setting X:Y to 7:3 or less, in other words, by setting X/Y to 7/3 or less, a desired bonding strength can be obtained and the shape retention of the plug can be improved. Examples 16 to 20 had better light-off performance than Comparative Example 15, which adopted an N plug.
In Example 21, the obtained performance was the same as in Example 19. It was found that by setting X:Y to 4:6 or more, in other words, by setting X/Y to 4/6 or more, the porosity of the porous plug 30 was increased and the light-off performance was further improved.
In addition, Examples 16 to 20 have better steady-state purification performance than Comparative Example 16, and the pressure loss is the same as Comparative Example 16. (improving purification performance without increasing loss) was also maintained.

(Modified example)
In each of the embodiments described above, the metal piece 31 and the brazing material are used as raw materials for manufacturing the porous plug 30, but the present invention is not limited to this, and an inorganic adhesive may be used instead of the brazing material. . In this case, a porous plug 30 in which adjacent metal pieces 31 are bonded with an inorganic adhesive is prepared in advance, and this porous plug 30 is arranged at one end or both ends of the winding core hollow part 6, and the inorganic adhesive It is sufficient to adhere it to the inner surface of the hollow part 6 of the winding core. As the inorganic adhesive, for example, an inorganic adhesive containing alumina as a main component (for example, Aron Ceramic D manufactured by Toagosei Co., Ltd.) can be used.

1 Catalytic converter 2 Flat foil 3 Corrugated foil 4 Metal honeycomb body 4a Through hole 5 Outer cylinder 6 Winding core hollow 30 Porous plug 31 Metal piece

Claims (19)

1. In a metal honeycomb body constructed by winding flat and corrugated metal foils around a predetermined axis,
   A metal honeycomb body characterized in that a plug made of a porous material is disposed at one end or both ends of a core hollow portion of the metal honeycomb body.
2. The metal honeycomb body according to claim 1, characterized in that the flat foil and/or corrugated foil has a large number of through holes formed therein.
3. The metal honeycomb body according to claim 1 or 2, wherein the porous body has a structure in which a large number of metal pieces are joined with a brazing material.
4. The metal piece is made of the same material as the metal foil,
   4. The metal honeycomb body according to claim 3, wherein the brazing material is made of the same material as a brazing material used for joining the flat foil and the corrugated foil.
5. The metal honeycomb body according to claim 1 or 2, wherein the porous body is composed of a large number of metal pieces and an inorganic adhesive that adheres adjacent metal pieces to each other.
6. The metal honeycomb body according to any one of claims 1 to 5, wherein the porous body has a porosity of 7% or more and 85% or less.
7. The porous body is disposed at both ends of the core hollow part of the metal honeycomb body,
   The metal honeycomb body according to any one of claims 1 to 6, wherein the porous body has a porosity of 70% or less.
8. The metal honeycomb body according to any one of claims 1 to 7, wherein the length in the axial direction of the porous body is 1 time or more and 3 times or less the diameter of the winding core hollow part. .
9. A metal honeycomb body according to any one of claims 1 to 8,
   an outer cylinder in which the metal honeycomb body is housed;
   A honeycomb unit characterized by having.
10. A catalytic converter in which a catalyst is supported on the metal honeycomb body according to any one of claims 1 to 8.
11. A catalytic converter in which a catalyst is supported on the metal honeycomb body in the honeycomb unit according to claim 9.
12. A method for manufacturing a honeycomb unit comprising the metal honeycomb body and outer cylinder according to claim 1,
    a base material supplying step of supplying a slurry-like base material containing a brazing material and a large number of metal pieces from an end of the hollow part of the winding core;
    a firing step of firing the honeycomb unit after the base material supplying step;
    has
    A brazing material is placed in advance at a predetermined portion of the honeycomb unit to be subjected to the firing step,
    The predetermined portion includes a portion where the flat foil and the corrugated foil are scheduled to be joined, and a portion where the metal honeycomb body and the outer cylinder are scheduled to be joined,
    In the base material supply step, when the total content of the metal pieces contained in the slurry base material is X mass % and the total content of the brazing material is Y mass %, the difference between X mass % and Y mass % A method for manufacturing a honeycomb unit, characterized in that the ratio X:Y is within a range of 3:7 to 9:1.
13. The base material supplying step is a step of supplying the slurry base material to both ends of the winding core hollow part,
    13. The method for manufacturing a honeycomb unit according to claim 12, wherein X:Y is within a range of 3:7 to 7:3.
14. After the firing step according to claim 12 or 13,
    a catalyst slurry inflow step of inflowing slurry containing a catalyst from an end in the axial direction of the honeycomb unit;
    A method for manufacturing a catalytic converter, characterized in that, after the catalyst slurry inflow step, a catalyst supporting step is performed in which the honeycomb unit is dried and fired to support a catalyst.
15. The method for manufacturing a honeycomb unit according to claim 12 or 13, wherein the flat foil and/or the corrugated foil has a large number of through holes formed therein.
16. 15. The method for manufacturing a catalytic converter according to claim 14, wherein the flat foil and/or the corrugated foil have a large number of through holes formed therein.
17. A method for manufacturing a metal honeycomb body according to claim 1, comprising:
    a base material supplying step of supplying a slurry-like base material containing a brazing material and a large number of metal pieces from an end of the hollow part of the winding core;
    After the base material supply step, a firing step of firing the metal honeycomb body;
    has
    In the base material supply step, when the total content of the metal pieces contained in the slurry base material is X mass % and the total content of the brazing material is Y mass %, the difference between X mass % and Y mass % A method for manufacturing a metal honeycomb body, characterized in that the ratio X:Y is within a range of 3:7 to 9:1.
18. After the calcination step according to claim 17,
    a catalyst slurry inflow step of inflowing a slurry containing a catalyst from an end in the axial direction of the metal honeycomb body;
    A method for manufacturing a catalytic converter, characterized in that, after the catalyst slurry inflow step, a catalyst supporting step is performed in which the metal honeycomb body is dried and fired to support a catalyst.
19. The method for manufacturing a catalytic converter according to claim 18, wherein the flat foil and/or the corrugated foil has a large number of through holes formed therein.

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