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

Abstract

The present invention provides a plug for a hollow part of a winding core that does not hinder ignition performance, stabilizes purification performance, and maintains the shape of the plug. The solution of the present invention is a metal honeycomb body formed by winding a flat foil and a corrugated foil composed of metal foil around a predetermined axis, characterized in that a plurality of through holes are formed in the flat foil and / or the corrugated foil, and a plug composed of a porous body is arranged at one end or both ends of the hollow part of the winding core of the metal honeycomb body.

Description

Technical Field

[0001] The present invention relates to a metal honeycomb body having a hollow core. Background Art

[0002] As a purification device for purifying vehicle exhaust gas, a metal honeycomb body is known in which a flat foil or a corrugated foil made of metal foil is wound around a predetermined axis. When the flat foil or the corrugated foil is wound, a winding core portion with a hollow structure is formed in the center of the metal honeycomb body. Since the purification performance of the winding core portion is low, it is required to reduce the exhaust gas flowing into the winding core portion.

[0003] Patent Document 1 discloses a purification device in which purification performance is improved by forming a plurality of through holes in a metal foil used for a metal honeycomb body.

[0004] Patent Document 2 discloses a technique in which a metal plug that blocks gas flow is disposed in a hollow portion of a winding core of a metal catalyst carrier using a metal honeycomb body formed by winding metal flat foil and corrugated foil.

[0005] Patent document 3 discloses the following technology: In a metal honeycomb body formed by winding metal flat foil and corrugated foil, a restriction portion is provided that expands the space between the starting ends of two metal foils at the axial ends of the hollow portion of the core to restrict the flow of exhaust gas in the core portion.

[0006] Prior Art Literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2005-535454;

[0009] Patent document 2: Japanese Patent Application Publication No. 2006-281118;

[0010] Patent document 3: Japanese Patent Application Publication No. 2010-201413. Summary of the invention

[0011] Problem that the invention aims to solve

[0012] Since a plurality of through holes are formed in the metal foil described in Patent Document 1, the pressure loss of the gas conduction path increases. When the pressure loss of the gas conduction path increases, the exhaust gas is easily discharged from the hollow portion of the winding core, and the effect (improvement of stable purification performance) brought about by forming a plurality of through holes cannot be fully enjoyed.

[0013] In the metal honeycomb of Patent Document 2, since a dense metal plug is used, the heat capacity of the metal honeycomb increases and the ignition performance (temperature characteristics showing the purification performance of the catalyst) deteriorates. In the case of a through hole formed on the foil, the area of ​​the foil material is only reduced by the amount of the hole area. Compared with a non-porous foil carrier of the same volume, the heat capacity is suppressed and the ignition performance is improved. However, if a sealing plug made of a dense material is inserted in the center, the heat capacity is only increased by the amount of the sealing plug, which damages the heat capacity reduction effect brought about by the hole in the foil. If the length of the plug is shortened, the heat capacity can be reduced, but the connection length of the plug relative to the hollow part of the core is insufficient, so the durability of the plug cannot be maintained.

[0014] The metal honeycomb body of Patent Document 3 is a method in which a restriction portion is provided by processing a metal foil, so the heat capacity is not increased, but the durability of the restriction portion is insufficient due to insufficient strength.

[0015] Means of solving the problem

[0016] In order to solve the above-mentioned problems, the metal honeycomb body of the present invention is characterized in that (1) in a metal honeycomb body formed by winding a flat foil and a corrugated foil composed of metal foil around a predetermined axis, a plug composed of a porous body is provided at one end or both ends of the hollow portion of the winding core of the metal honeycomb body.

[0017] (2) The metal honeycomb body according to (1) above, wherein a plurality of through holes are formed in the flat foil and / or the corrugated foil.

[0018] (3) The metal honeycomb body according to (1) or (2) above, wherein the porous body has a structure in which a plurality of metal sheets are joined together by brazing material.

[0019] (4) The metal honeycomb body according to (3) above, wherein the metal sheet 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 for joining the flat foil and the corrugated foil.

[0020] (5) The metal honeycomb body according to (1) or (2) above, wherein the porous body includes a plurality of metal sheets and an inorganic adhesive for bonding adjacent metal sheets to each other.

[0021] (6) The metal honeycomb body according to any one of (1) to (5) above, wherein the porosity of the porous body is 7% or more and 85% or less.

[0022] (7) The metal honeycomb body according to any one of (1) to (6) above, wherein the porous body is disposed at both ends of a hollow portion of a winding core of the metal honeycomb body, and the porosity of the porous body is 70% or less.

[0023] (8) The metal honeycomb body according to any one of (1) to (7) above, wherein the length of the porous body in the axial direction is not less than 1 time and not more than 3 times the diameter of the hollow portion of the winding core.

[0024] (9) A honeycomb unit, comprising: the metal honeycomb body according to any one of (1) to (8) above; and an outer cylinder that accommodates the metal honeycomb body.

[0025] (10) A catalytic converter comprising a metal honeycomb body according to any one of (1) to (8) above and a catalyst supported thereon.

[0026] (11) A catalytic converter, wherein a catalyst is supported on the metal honeycomb body of the honeycomb unit described in (9) above.

[0027] (12) A method for manufacturing a honeycomb unit, the honeycomb unit comprising the metal honeycomb body and an outer cylinder as described in (1) above, the method comprising: a base material supplying step, supplying a slurry-like base material comprising a brazing material and a plurality of metal sheets from the end of the hollow portion of the winding core; and a firing step, firing the honeycomb unit after the base material supplying step, wherein the brazing material is pre-arranged at a predetermined portion of the honeycomb unit to be supplied to the firing step, the predetermined portion comprising a predetermined joining portion of the flat foil and the corrugated foil, and a predetermined joining portion of the metal honeycomb body and the outer cylinder, and in the base material supplying step, when the total content of the metal sheets contained in the slurry-like base material is set to X mass % and the total content of the brazing material is set to Y mass %, the ratio of X mass % to Y mass %, i.e., X:Y, is within the range of 3:7 to 9:1.

[0028] (13) The method for manufacturing a honeycomb unit according to (12) above, wherein the matrix supplying step is a step of supplying the slurry matrix to both ends of the hollow portion of the winding core, and X:Y is within a range of 3:7 to 7:3.

[0029] (14) A method for manufacturing a catalytic converter, characterized in that after the calcination step described in (12) or (13) above, the following steps are implemented: a catalyst slurry inflow step, in which a slurry containing a catalyst is made to flow in from the axial end of the honeycomb unit; and a catalyst loading step, in which after the catalyst slurry inflow step, the honeycomb unit is dried and calcined to load the catalyst.

[0030] (15) The method for manufacturing a honeycomb unit according to (12) or (13) above, characterized in that a plurality of through holes are formed in the flat foil and / or the corrugated foil.

[0031] (16) The method for manufacturing a catalytic converter according to (14) above, characterized in that a plurality of through holes are formed in the flat foil and / or the corrugated foil.

[0032] (17) A method for manufacturing a metal honeycomb body as described in (1) above, characterized in that it comprises: a base material supplying step, supplying a slurry-like base material containing a brazing material and a plurality of metal sheets from the end of the hollow portion of the winding core; and a firing step, firing the metal honeycomb body after the base material supplying step, wherein in the base material supplying step, when the total content of the metal sheets contained in the slurry-like base material is set to X mass % and the total content of the brazing material is set to Y mass %, the ratio of X mass % to Y mass %, i.e., X:Y, is within the range of 3:7 to 9:1.

[0033] (18) A method for manufacturing a catalytic converter, characterized in that after the sintering step described in (17) above, the following steps are implemented: a catalyst slurry inflow step, in which a slurry containing a catalyst is made to flow into the metal honeycomb from the axial end of the metal honeycomb body; and a catalyst loading step, in which after the catalyst slurry inflow step, the metal honeycomb body is dried and sintered to load the catalyst.

[0034] (19) The method for manufacturing a catalytic converter according to (18) above, characterized in that a plurality of through holes are formed in the flat foil and / or the corrugated foil.

[0035] Effects of the Invention

[0036] According to the present invention, by arranging a porous plug at one or both ends of the hollow portion of the winding core, it is possible to suppress exhaust gas from being discharged from the hollow portion of the winding core, thereby improving the stable purification performance of the metal honeycomb body.

[0037] Furthermore, since the plug is composed of a porous body, the heat capacity of the metal honeycomb body can be reduced compared to the case where a dense plug is used, thereby improving the ignition performance of the metal honeycomb body.

[0038] Furthermore, compared with a method of restricting the inflow of exhaust gas by processing a metal foil, the shape maintenance property of the plug can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a top view of a catalytic converter.

[0040] Figure 2 It is a cross-sectional view of the hollow portion of the winding core with porous plugs provided at both ends.

[0041] Figure 3 This is a developed view of the metal foil and an enlarged view of a portion of the metal foil.

[0042] Figure 4 It is a cross-sectional view of a porous plug.

[0043] Figure 5 This is a cross-sectional photograph of the porous plug in the hollow portion of the winding core (X:Y=5:5).

[0044] Figure 6 It is a cross-sectional view of the hollow portion of the winding core with a porous plug provided at one end. DETAILED DESCRIPTION

[0045] Hereinafter, embodiments of the present invention will be described.

[0046] The metal honeycomb body of the first embodiment is composed of a metal foil having through holes formed therein, and porous plugs are provided at both ends of the hollow portion of the winding core.

[0047] The metal honeycomb body according to the second embodiment is composed of a metal foil having through holes formed therein, and a porous plug is provided at one end of a hollow portion of a winding core.

[0048] The metal honeycomb body according to the third embodiment is composed of a metal foil in which no through-holes are formed, and porous plugs are provided at both ends of the hollow portion of the winding core.

[0049] The metal honeycomb body according to the fourth embodiment is composed of a metal foil in which no through-holes are formed, and a porous plug is provided at one end of a hollow portion of a winding core.

[0050] Hereinafter, each embodiment will be described.

[0051] (First Embodiment)

[0052] Figure 1 This is a plan view of a catalytic converter as one embodiment of the present invention as viewed from the axial direction. However, the porous plug disposed in the hollow portion of the winding core is omitted from the illustration. In addition, the axial direction is also the conduction direction of the exhaust gas flowing into the catalytic converter.

[0053] Figure 2 It is a cross-sectional view of the hollow portion of the winding core of the catalytic converter, showing the placement position of the porous plug. Figure 3 It is a developed view of a metal foil serving as a base of a flat foil and a corrugated foil and an enlarged view of a part of the metal foil.

[0054] The catalytic converter 1 includes a metal honeycomb body 4 carrying a catalyst and an outer cylinder 5. However, the outer cylinder 5 may be omitted. The metal honeycomb body 4 is composed of a winding body formed by overlapping and winding a flat foil 2 and a corrugated foil 3. 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 exhaust gas of a vehicle.

[0055] The flat foil 2 and the corrugated foil 3 can use 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 thinner metal foil in this way, the heating rate of the metal honeycomb body 4 is increased during exhaust gas purification, which can activate the catalyst or make the catalytic converter 1 lighter.

[0056] A plurality of through holes 4a are formed in the metal foil that serves as the base of the flat foil 2 and the corrugated foil 3. By forming a plurality 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 turbulent, which can improve the stable purification performance. In addition, since the heat capacity of the metal honeycomb body 4 is reduced, the ignition performance can be improved.

[0057] However, the plurality of through holes 4 a may be formed only in the flat foil 2 , or the plurality of through holes 4 a may be formed only in the bump foil 3 .

[0058] If the diameter of the through hole 4a is too small, the through hole 4a may be clogged with the catalyst. Therefore, the diameter of the through hole 4a is preferably 0.2 mm or more.

[0059] If the diameter of the through hole 4a is too large, the stable purification performance may be lowered compared to a metal honeycomb body without through holes. Therefore, the diameter of the through hole 4a is preferably 8 mm or less.

[0060] In order to reduce the heat capacity of the metal honeycomb body 4, the opening ratio of the through holes 4a is preferably 20% or more. In order to improve the durability of the metal honeycomb body 4, the opening ratio of the through holes 4a is preferably 60% or less.

[0061] The predetermined area on the gas inlet side of the metal honeycomb body 4 (hereinafter also referred to as the gas inlet side non-opening portion) is preferably set as a non-opening portion without the through hole 4a. The gas inlet side non-opening portion is preferably set to be more than 1 mm from the gas inlet side end. In this way, the strength of the foil can be maintained, and the bonding area between the porous plug and the foil can be sufficiently ensured.

[0062] Since the plug of this embodiment is porous, if the entire plug is bonded to the region having the opening, the bonding area is 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.

[0063] Furthermore, the gas inlet-side non-opening portion is preferably set to be 10 mm or less from the gas inlet-side end portion.

[0064] The predetermined area on the gas outlet side of the metal honeycomb body 4 (hereinafter also referred to as the gas outlet side non-opening portion) is preferably set as a non-opening portion without the through hole 4a. The gas outlet side non-opening portion is preferably set to be more than 1 mm from the gas inlet side end. The reason is the same as that of the gas inlet side non-opening portion, so the description is omitted.

[0065] Furthermore, the gas outlet side non-opening portion is preferably set to be 10 mm or less from the gas outlet side end portion.

[0066] like Figure 3 As shown in FIG. 1 , the through holes 4a of this embodiment are arranged in a staggered manner relative to the metal foil. Here, a triangle is drawn with the centers of three adjacent through holes 4a connected by a line. When the area inside the triangle is defined as the "overall area" and the area of ​​the overlapping portion of the triangle indicated by black and the through hole 4a is defined as the "hole area", the ratio of the "hole area" to the "overall area" can be defined as the "opening ratio". The calculation method of the opening ratio is technical common sense, so it is limited to the above description.

[0067] In this embodiment, the through holes 4a are circular in shape, but may be other shapes (such as elliptical, polygonal, etc.) Also, the through holes 4a are not limited to being arranged in a staggered pattern, but may be arranged in other patterns (such as a lattice pattern).

[0068] The lower limit of the plate width of the metal foil is preferably 3 times the diameter of the core hollow portion 6 described later. The upper limit of the plate width of the metal foil is preferably 500 mm. The size of the metal foil can be appropriately changed according to the purpose of the catalytic converter 1. The corrugated foil 3 can be manufactured by corrugating the metal foil, for example.

[0069] Here, the metal foil may be various heat-resistant stainless steels containing Al in the alloy composition, for example. The stainless steel may be a ferritic stainless steel containing 20 mass% Cr, 5 mass% Al, and the remainder Fe and inevitable impurities (in other words, a Fe-20Cr-5Al alloy). However, other stainless steels (for example, stainless steel containing 15 to 25 mass% Cr and 2 to 8 mass% Al) may also be used.

[0070] Brazing material can be used to join the flat foil 2 and the corrugated foil 3 and to join the metal honeycomb body 4 and the outer tube 5. For example, a Ni-based brazing material with high heat resistance can be used as the brazing material. The brazing material may be a foil brazing material or a powder brazing material.

[0071] The catalyst can be supported on the metal foil by coating a predetermined wash liquid on the surface of the metal foil of the metal honeycomb body 4, and drying and firing the wash liquid. The method of coating the wash liquid will be described later.

[0072] The outer tube 5 can be made of, for example, ferritic stainless steel such as SUS436L or SUS430, which contains about 13 mass % or more and 20 mass % or less of Cr.

[0073] The lower limit of the wall thickness of the outer cylinder 5 is preferably 0.5 mm. The upper limit of the wall thickness of the outer cylinder 5 is preferably 3 mm.

[0074] The lower limit of the cell density of the metal honeycomb body 4 is preferably 15.5 cells per 1 square centimeter (in other words, 100 cells per 1 square inch). The upper limit of the cell density of the metal honeycomb body 4 is preferably 93 cells per 1 square centimeter (in other words, 600 cells per 1 square inch).

[0075] A core hollow portion 6 extending in a cylindrical shape in the axial direction is formed at the center of the metal honeycomb body 4. Porous plugs 30 are provided at both ends of the core hollow portion 6. Figure 4 A cross section of the porous plug 30 is schematically shown.

[0076] A plug slurry (equivalent to a slurry-like base material) is prepared by mixing a plurality of metal sheets 31 and a brazing material in a fragmented or powdered form in a liquid having a moderate viscosity, and the plug slurry is injected from one end side and the other end side of the winding core hollow portion 6, followed by drying and firing, thereby enabling the porous plug 30 to be arranged at both ends of the winding core hollow portion 6. Therefore, the porous plug 30 has a structure in which a plurality of metal sheets 31 are joined by a brazing material. Since a plurality of voids are formed in the porous plug 30, the heat capacity is lower than that of a conventional dense plug, and the ignition performance can be improved.

[0077] The present inventors believe that the mechanism of void formation is as follows: A plug slurry containing metal sheet 31 and brazing material is injected into the core hollow portion 6, and then the liquid component is removed by drying. Furthermore, the brazing material melts during firing, and the molten brazing material penetrates into the gaps between the metal sheets, thereby forming voids.

[0078] Figure 4 The dotted lines indicate the positions of both ends of the porous plug 30, and the volume ratio of the voids in the region sandwiched by these dotted lines becomes the porosity of the porous plug 30. Figure 4 Only the porous plug 30 at one end is shown in the figure.

[0079] That is, it is possible to define a surface ( Figure 4 The area enclosed by the inner surface of the core hollow portion 6 and the area surrounded by the voids is defined as the ratio of the volume occupied by the voids to the volume of the area as the "void ratio". With regard to the upper and lower end surfaces of the porous plug 30, one end and the other end in the length direction of the core hollow portion 6 are defined in the solid portion of the porous plug 30 excluding the voids, and the surface passing through the one end and the surface passing through the other end can be defined as the "upper and lower end surfaces".

[0080] For example, the porous plug 30 is taken as an imaging object, a plurality of X-ray CT images are taken, these CT cross-sectional images are binarized and separated into a solid part and a void part, and the area ratio of the void is calculated, thereby calculating the porosity of the porous plug 30 .

[0081] Specifically, the arithmetic mean of the area ratios of the voids in each CT cross-sectional image can be taken as the porosity of the porous plug 30 .

[0082] 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 ignition performance of the metal honeycomb body 4 can be improved.

[0083] The porosity of the porous plug 30 is preferably 85% or less. When the metal sheet 31 and the brazing material are used as raw materials, if the porosity is too high, the solid phase bonding of the metal sheets without the brazing material becomes dominant, and the strength of the porous plug 30 itself (i.e., the shape maintenance of the plug) cannot be maintained.

[0084] In addition, if the porosity of the porous plug 30 is suppressed to below 85%, it is possible to effectively prevent the exhaust gas from leaking out of the core hollow portion 6. That is, a plurality of through holes 4a are formed on the metal foil (flat foil 2 and corrugated foil 3) of the present embodiment, and the pressure loss of the metal honeycomb body 4 becomes larger, so the exhaust gas is easily discharged from the core hollow portion 6. In particular, when the flow rate of the exhaust gas is a high flow rate, this tendency becomes significant. In the present embodiment, both ends of the core hollow portion 6 are blocked by the porous plug 30, so it is possible to effectively prevent the exhaust gas from being discharged from the core hollow portion 6. As a result, the stable purification performance of the metal honeycomb body 4 can be improved.

[0085] When the diameter of the winding core hollow portion 6 is defined as D, the axial length of the porous plug 30 is preferably greater than D. By setting the axial length of the porous plug 30 to be greater than D, the bonding area of ​​the porous plug 30 with respect to the winding core hollow portion 6 can be sufficiently ensured, thereby preventing the porous plug 30 from falling off from the winding core hollow portion 6.

[0086] The axial length of the porous plug 30 is preferably not more than 3D. By setting the axial length of the porous plug 30 to not more than 3D, the effect of reducing the heat capacity by the porous plug 30 can be more effectively exhibited.

[0087] The brazing material of the porous plug 30 is preferably the same brazing material as that used in the joining of the flat foil 2 and the corrugated foil 3. For example, when a Ni-based brazing material is used as the joining material of the flat foil 2 and the corrugated foil 3, it is preferable to use the same Ni-based brazing material as the brazing material of the porous plug 30. In this way, the heat resistance and thermal expansion of the joining part of the flat foil 2 and the corrugated foil 3 and the joining part of the metal sheet 31 can be made equal. For example, the Ni-based brazing material can use BNi-1 to BNi-7 specified in "JISZ 3265", BNi-5a, BNi-8, BNi-9, BNi-10, BNi-11, BNi-12, BNi-13, etc. published by AWS (American Welding Society). However, if the thermal expansion coefficients of the brazing materials are relatively close, the types of brazing materials may be different.

[0088] The metal sheet 31 is preferably made of the same metal as the flat foil 2 and the bump foil 3. This allows the metal sheet 31, the flat foil 2, and the bump foil 3 to have equal heat resistance and thermal expansion. However, the types of metals may be different as long as the thermal expansion coefficients are relatively close.

[0089] The shape of the metal sheet 31 is not particularly limited, and may be, for example, a disk shape, a sphere shape, a triangular pyramid shape, a cube shape, etc. In addition, metal sheets 31 of different shapes may be mixed to form the porous plug 30. However, if the metal sheet 31 is formed into a disk shape, the aspect ratio becomes large, and it is easy to form a gap. Therefore, it is preferred to use a disk-shaped metal sheet 31.

[0090] Next, a method for arranging the porous plug 30 in the winding core hollow portion 6 is specifically described. A plug slurry (equivalent to a slurry-like base material) is prepared by mixing a plurality of metal flakes 31 and a brazing material in a fragmented or powdered state in a liquid having a moderate viscosity. When the total content of the metal flakes 31 in the liquid plug slurry is X mass % and the total content of the brazing material is Y mass %, the ratio of X mass % to Y mass %, i.e., X:Y, is within the range of 3:7 to 9:1. When the condition of the mixing ratio is expressed as a fraction, X / Y is 3 / 7 or more and 9 / 1 or less.

[0091] If X / Y is too small, the shape of the plug cannot be maintained. In other words, if there is too much brazing material, the brazing material flows down during firing, so that a fired body in the shape of a plug cannot be obtained.

[0092] If X / Y is too large, the strength of the porous plug 30 itself decreases. In other words, the brazing material is insufficient, the solid phase bonding of the metal pieces without the brazing material becomes dominant, and the brazing strength of the adjacent metal pieces 31 decreases, so the plug shape cannot be maintained.

[0093] The preferred lower limit of X:Y is 4:6. In other words, the preferred lower limit of X / Y is 4 / 6. By setting X / Y to 4 / 6 or more, the porosity of the porous plug 30 is increased, and the light-off performance of the catalytic converter 1 is improved. That is, the amount of brazing material filling the voids is reduced, so the porosity of the porous plug 30 can be increased.

[0094] The preferred upper limit of X:Y is 7:3. In other words, the preferred upper limit of X / Y is 7 / 3. By setting X / Y to 7 / 3 or less, the brazing strength of the adjacent metal sheets 31 is improved, and the shape maintenance of the plug can be further improved.

[0095] Here, Figure 5 This is a photograph of a porous plug when X:Y is set to 5:5. As can be seen from this photograph, the plug shape is maintained.

[0096] A predetermined amount of the prepared plug slurry is injected into the core hollow portion 6 from both ends of the core hollow portion 6 and then dried.

[0097] After the plug slurry is injected and dried, the metal honeycomb body 4 is fired at a temperature of about 1200°C in a vacuum environment (corresponding to the "firing treatment step" described later). When the metal honeycomb body 4 is fired, adjacent metal sheets 31 are brazed to each other by the molten brazing material. In addition, the molten brazing material also adheres to the inner surface of the winding core hollow portion 6, so that the porous plug 30 can be held at the predetermined arrangement position at both ends of the winding core hollow portion 6.

[0098] Next, a method for manufacturing the honeycomb unit and the catalytic converter will be described.

[0099] 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 arranging the brazing material at the predetermined joint portion of the flat foil 2 and the corrugated foil 3, a process B of arranging the brazing material at the predetermined joint portion of the metal honeycomb body 4 and the outer cylinder 5, and a process C of injecting the plug slurry into the hollow part 6 of the winding core. The means of arranging the brazing material is not particularly limited, and for example, the coating of the powdered brazing material can be used as the arranging means, and the temporary fixation based on the foil brazing material can also be used as the arranging means.

[0100] Step A may be performed while the flat foil 2 and the corrugated foil 3 are being wound around a predetermined axis, or after the winding. When performed after the winding, for example, step A can be performed by spreading the brazing material from above the metal honeycomb body 4 toward the intended joining portion.

[0101] Step B can be implemented after step A. For example, after the implementation of step A, a strip of foil brazing material is wound around the predetermined joint portion of the metal honeycomb body 4, and the metal honeycomb body 4 wound with the foil brazing material is inserted into the outer tube 5, and then the outer tube 5 is reduced in diameter and pressed against the metal honeycomb body 4 wound with the foil brazing material, thereby achieving step B. The reduction means can use a compression means for compressing the outer tube 5 radially inward. In addition, step B is not limited to the reduction means. For example, step B can also be achieved by pressing the metal honeycomb body 4 wound with the foil brazing material into the outer tube 5.

[0102] However, step B may be performed before step A. For example, after the flat foil 2 and the corrugated foil 3 are wound around a predetermined axis to produce the metal honeycomb body 4, step B may be performed by winding the foil brazing material, and after step B is performed, step A may be performed by spreading the brazing material.

[0103] The order of step C is not particularly limited. As shown in the embodiments described below, it can be performed after step A and step B, or before step A and / or step B. However, step C is a step of injecting the plug slurry into the core hollow portion 6, and therefore needs to be performed after at least the flat foil 2 and the corrugated foil 3 are wound around a predetermined axis.

[0104] The calcination process performed after the preparation process will not be described again. By performing the calcination process after processes A to C, the porous plug 30 can be manufactured and installed, the flat foil 2 and the corrugated foil 3 can be joined, and the metal honeycomb body 4 and the outer cylinder 5 can be joined at the same time.

[0105] Next, a method for manufacturing a catalytic converter will be described in detail.

[0106] After the honeycomb unit is manufactured (in other words, after the calcination step is performed), the catalyst is supported on the metal honeycomb body 4. The catalyst can be supported by, for example, an impregnation method or a suction method.

[0107] The impregnation method is a method of immersing the metal honeycomb body 4, i.e., the honeycomb unit, connected to the outer cylinder 5, in a wash liquid to apply a catalyst to the metal foil constituting the metal honeycomb body 4 (equivalent to the "catalyst slurry inflow step"). The wash liquid can be, for example, a slurry-like liquid obtained by stirring γ-alumina powder, lanthanum oxide, zirconium oxide, and cerium oxide in an aqueous solution of palladium nitrate.

[0108] Here, when the porous plug 30 is provided only on one end side of the winding core hollow portion 6, the wash solution containing the catalyst flows in from the other end side of the winding core hollow portion 6. Therefore, there is a possibility that the excess catalyst is accumulated inside the winding core hollow portion 6. In order to solve this problem, it is necessary to open a through release hole in the porous plug 30 using a drill or the like, which increases the number of processing steps.

[0109] According to the present embodiment, both ends of the winding core hollow portion 6 are blocked by the porous plugs 30, so when the honeycomb unit is immersed in the washing liquid, the washing liquid can be prevented from flowing into the inner side of the winding core hollow portion 6. As a result, the amount of catalyst used is reduced, so that the cost can be reduced. In addition, the step of forming the through-release hole in the porous plug 30 can be omitted.

[0110] The suction method is a method of sucking a wash coating liquid containing a catalyst from the axial direction of the metal honeycomb body 4 to apply the catalyst to the metal foil constituting the metal honeycomb body 4 (corresponding to the "catalyst slurry inflow step"). In the suction method, as described in the immersion method, both ends of the winding core hollow portion 6 are blocked with a porous plug 30, thereby preventing the wash coating liquid from flowing into the winding core hollow portion 6.

[0111] After the wash coating liquid is applied to the metal foil of the metal honeycomb body 4, it is dried and fired, thereby the coated catalyst can be loaded on the metal foil (equivalent to the "catalyst loading step"). The firing conditions are appropriately set according to the inner diameter of the cell, the axial length of the metal honeycomb body 4, the type of wash coating 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. After the catalyst flows in, it is dried and fired, thereby the catalyst can be loaded.

[0112] In addition, when the catalytic converter 1 does not have the outer cylinder 5, the catalytic converter can also be manufactured by applying the wash liquid on the metal honeycomb body 4 by the above-mentioned method, drying it, and firing it.

[0113] Here, if the porosity of the porous plug 30 is suppressed to 70% or less, the inflow of the washing liquid into the core hollow portion 6 can be effectively prevented.

[0114] When the porous plugs 30 are disposed at both ends of the winding core hollow portion 6, the metal honeycomb body 4 may be disposed with one axial end side or the other axial end side facing the exhaust gas upstream side.

[0115] (Second Embodiment)

[0116] Figure 6 1 is a cross-sectional view of the hollow part of the winding core in the catalytic converter of the present embodiment, showing the arrangement position of the porous plug. The porous plug 30 of the present embodiment is arranged only at one end (preferably the end on the gas inlet side) of the hollow part 6 of the winding core, which is different from the first embodiment in which the porous plug 30 is arranged at both ends of the hollow part 6 of the winding core. The configuration of the catalytic converter of the present embodiment is the same as that of the catalytic converter of the first embodiment except for the arrangement position of the porous plug 30, so only the porous plug 30 will be described.

[0117] The porous plug 30 can be disposed at one end of the winding core hollow portion 6 by preparing a slurry obtained by mixing a plurality of metal pieces 31 and a brazing material in a liquid having a moderate viscosity, injecting the slurry into one end of the winding core hollow portion 6 , and then drying and firing the slurry.

[0118] The preferred porosity of the porous plug 30 is the same as that of the first embodiment, and thus detailed description thereof is omitted. The preferred axial length of the porous plug 30 is the same as that of the first embodiment, and thus detailed description thereof is omitted.

[0119] The material of the porous plug 30 and the shape of the metal sheet 31 are also the same as those of the first embodiment, and thus detailed descriptions thereof are omitted.

[0120] In the present embodiment, the porous plug 30 is not provided at the other end of the winding core hollow portion 6. Therefore, when the wash coating liquid is applied to the metal honeycomb body 4, the wash coating liquid flows in from the other end of the winding core hollow portion 6. Therefore, a through-release hole may be formed in the porous plug 30, and the wash coating liquid flowing into the winding core hollow portion 6 may be discharged from the through-release hole. In this way, it is possible to prevent the excess catalyst from accumulating in the winding core hollow portion 6.

[0121] In addition, the through-hole can also be formed by drilling a hole in the porous plug 30 after heat treatment using a drill or the like. The through-hole is also described in paragraph 0023 of Patent Document 2, and thus a detailed description is omitted. In addition, the "through hole 10" in Patent Document 2 is equivalent to the "through-hole" in this specification.

[0122] In the first embodiment, in order to prevent the washing liquid from flowing into the winding core hollow portion 6, the upper limit of the porosity of the porous plug 30 is set to 70% as a preferred condition, but in the present embodiment, the washing liquid is allowed to flow into the winding core hollow portion 6, and through holes are formed in the porous plug 30, thereby discharging the washing liquid. Therefore, the description of the first embodiment is not cited regarding the point that the upper limit of the porosity of the porous plug 30 is set to 70%.

[0123] The configuration of the plug slurry used in manufacturing the porous plug 30 is the same as that of the first embodiment, and thus detailed description thereof is omitted. The catalyst supporting method is also described in the first embodiment, and thus detailed description thereof is omitted.

[0124] In the second embodiment, the porous plug 30 may be disposed toward the exhaust gas inlet side, or the porous plug 30 may be disposed toward the exhaust gas outlet side.

[0125] (Third Embodiment)

[0126] 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 portion 6. However, it is different from the catalytic converter of the first embodiment in that the through holes 4a are not formed in the flat foil 2 and the corrugated foil 3. Except for this difference, the description of the first embodiment is applied to this embodiment.

[0127] Since the through holes 4 a are not formed in the flat foil 2 and the corrugated foil 3 of the present embodiment, a catalytic converter with a small pressure loss can be provided.

[0128] (Fourth Embodiment)

[0129] The catalytic converter of this embodiment is the same as the catalytic converter of the second embodiment in that a porous plug 30 is provided at one end of the winding core hollow portion 6. However, it is different from the catalytic converter of the second embodiment in that no through hole 4a is formed in the flat foil 2 and the corrugated foil 3. Except for this difference, the description of the second embodiment is applied to this embodiment.

[0130] Since the through holes 4 a are not formed in the flat foil 2 and the corrugated foil 3 of the present embodiment, a catalytic converter with a small pressure loss can be provided.

[0131] Next, the present invention will be specifically described with reference to examples.

[0132] (First embodiment)

[0133] The first example corresponds to the first embodiment.

[0134] A plurality of samples having different mixing ratios of the metal sheet and the brazing filler metal were prepared, and the shape maintenance property, light-off performance, catalyst inflow prevention effect, and stable purification performance of the plug were evaluated.

[0135] A corrugated foil and a flat foil are wound in an overlapping state to manufacture a metal honeycomb body having a hollow core. The metal foil (foil thickness: 50 μm) of the corrugated foil and the flat foil uses a ferritic stainless steel composed of 20 mass% Cr, 5 mass% Al, and the remainder of Fe and inevitable impurities. In addition, a metal foil having a plurality of through holes is used. The through holes are circular with a diameter of 0.9 mm. The through holes are arranged in a staggered manner. The opening ratio is set to 40%. In addition, the opening ratio is calculated by the method described in the embodiment. In addition, a 5 mm wide non-opening portion is provided at the end of the gas inlet side and the gas outlet side. The diameter, length, cell density and diameter of the hollow core of the metal honeycomb body are set to 33 mm, 60 mm, 300 cpsi and 5 mm, respectively. BNi-5 (refer to JISZ 3265) is used as the bonding material (brazine) of the corrugated foil and the flat foil. The treatment of the bonding material of the corrugated foil and the flat foil is implemented before injecting the slurry for the plug.

[0136] After a foil-like brazing material was wound around the intended joining portion of the outer peripheral surface of the metal honeycomb body, 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 slurry injection treatment and a sintering treatment were performed under the following conditions.

[0137] The metal sheet used for the porous plug uses a metal of the same composition as the corrugated foil and the flat foil. The brazing material uses a powdered brazing material of the same composition as the brazing material used in the joining of the corrugated foil and the flat foil. The metal sheet is in the shape of a circular plate with a diameter of 0.9 mm and a thickness of 0.05 mm. A slurry for the plug containing the metal sheet and the brazing material is injected from both ends of the hollow part of the core of the metal honeycomb body, and then dried at 200°C in the atmosphere. After drying, the honeycomb unit is sintered at 1200°C in a vacuum, thereby providing a porous plug with an axial length of 10 mm at both ends of the hollow part of the core. In addition, as mentioned above, the diameter of the hollow part of the core is 5 mm, so the diameter of the porous plug is also 5 mm.

[0138] Then, as a catalyst, a slurry-like liquid prepared by stirring γ-alumina powder, lanthanum oxide, zirconium oxide, and cerium oxide in an aqueous solution of palladium nitrate is used to apply the catalyst on a metal foil, and after drying at 200°C, the catalyst is calcined at 500°C for 1 hour in the air to manufacture a catalytic converter.

[0139] Regarding the matching ratio of metal sheet and brazing material (X:Y), Example 1 is 5:5, Example 2 is 3:7, Example 3 is 4:6, Example 4 is 7:3, Example 5 is 9:1, Comparative Example 1 is 1:9, and Comparative Example 2 is 9.5:0.5.

[0140] Three samples were prepared for each of Examples 1 to 5 and Comparative Example 1, and the porosity was measured. However, the metal sheet matching ratio of Comparative Example 1 was too low, and none of the samples became plugs, so the porosity was not measured. Regarding the porosity, as described in the embodiment, 10 X-ray CT images of the porous plug were obtained, and each X-ray CT image was binarized and image analysis was performed to obtain the arithmetic mean of the porosity. In addition, in this embodiment, only the porosity of the porous plug arranged at one end was measured.

[0141] In Comparative Example 3, a dense plug (hereinafter also referred to as an N plug) is provided instead of the porous plug. The N plug uses the same material as the metal sheet of the porous plug. The axial length of the N plug is set to 10 mm, similarly to the porous plug of the embodiment. In Comparative Example 4, no porous plug and N plug are provided. In Comparative Example 5, a conical clamp is pressed into the overlapping portion of the flat foil and the corrugated foil extending toward the hollow portion of the winding core and expanded, thereby providing a restriction portion for restricting the inflow of exhaust gas (i.e., the center shape processing of Patent Document 3).

[0142] The shape maintenance of the plug was evaluated by pressing a porous plug 30 provided at one end side with a rod from the upper end surface, and the shape change of the plug after unloading was evaluated. The size of the rod was φ4mm, the pressing distance of the rod was 20mm, and the pressing speed of the rod was 1.0mm / second. Here, in the case where the metal sheets constituting the porous plug are firmly joined by brazing material, the porous plug will not deform even if a load is applied, and the original shape can be maintained. On the other hand, the shape of the porous plug in which the metal sheets are weakly joined to each other changes due to the load. The shape change affects the sealing range of the porous plug. In the case where the metal sheets are weakly joined to each other, the porous plug becomes scattered when the metal honeycomb body is used. If it is scattered, the original function of the plug to inhibit the gas from flowing into the hollow part of the core (in other words, to prevent air leakage) will be lost.

[0143] Therefore, in this embodiment, the case where the shape after the load test does not change from the original shape is evaluated as very good shape maintenance and is AAA, the case where the axial reduction is within 1 mm is evaluated as good shape maintenance and is AA, the case where the reduction exceeds 1 mm but can be evaluated as ensuring the bonding of the metal sheets and the sealing of the sealing parts is possible is evaluated as slightly good shape maintenance and is A, and the case where it is judged that the shape change is large and the sealing parts cannot be properly sealed is evaluated as poor shape maintenance and is B.

[0144] The metal honeycomb is cut axially at the position where the catalyst is installed in the hollow part of the winding core, and the degree of catalyst infiltration is visually confirmed to evaluate the catalyst inflow prevention effect. In the case where the catalyst is not immersed in the porous plug, the catalyst inflow prevention effect is considered to be very good and is evaluated as AAA. In the case where the infiltration of the catalyst into the porous plug is stopped halfway, the inflow prevention effect is considered to be good and is evaluated as AA. In the case where the infiltration of the catalyst relative to the hollow part of the winding core is confirmed only in a part of the tested samples, the catalyst inflow prevention effect is considered to be slightly good and is evaluated as A. In the case where the catalyst is confirmed to be immersed in the hollow part of the winding core in all the tested samples, the catalyst inflow prevention effect is considered to be poor and is evaluated as B.

[0145] Ignition performance is at SV (space velocity): 100,000h -1Under the conditions of , simulated gas was flowed into the metal honeycomb, and the gas temperature was gradually increased from room temperature. The HC conversion rate (%) at each temperature was measured, and the time (τ50) when the conversion rate reached 50% was used for evaluation based on the conversion rate-temperature curve. τ50 of less than 9 seconds was evaluated as AAA, less than 11 seconds was evaluated as AA, less than 13 seconds was evaluated as A, and more than 13 seconds was evaluated as B. In addition, based on the conversion rate-temperature curve, according to the temperature (T80) when the conversion rate reached 80%, the case where T80 was less than 230°C was set as AA, less than 240°C was set as A, and more than 240°C was set as B, thereby evaluating the stable purification performance. The simulated gas used HC (propane, C 3 H 6 ): 550ppm (1650ppmC), NO: 500ppm, CO: 0.5%, O 2 :1.5%、H 2 O: 10%, the rest is N 2 Simulated gas (simulated gas of diesel exhaust).

[0146] [Table 1]

[0147]

[0148]

[0149] Compared with Comparative Example 5 which uses center shape processing as a limiting means, Examples 1 to 5 have improved shape maintenance of the plug. Since Comparative Example 2 has too little brazing material, the evaluation of the shape maintenance of the plug is B. In addition, it can be seen that by setting X:Y to 7:3 or less, in other words, by setting X / Y to 7 / 3 or less, the desired bonding strength can be obtained and the shape maintenance of the plug can be improved. Compared with Comparative Example 3 which uses an N plug, Examples 1 to 5 have improved ignition performance. It can be seen 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 is increased, and the ignition performance is further improved.

[0150] It is understood that by setting X:Y to 7:3 or less, in other words, by setting X / Y to 7 / 3 or less, the effect of preventing the inflow of the catalyst can be obtained.

[0151] In addition, Examples 1 to 5 are superior in stable purification performance compared to Comparative Example 4, and the original purpose of the plug (restricting the inflow of exhaust gas into the hollow portion of the core and improving purification performance) can be maintained.

[0152] (Second embodiment)

[0153] The second example corresponds to the second implementation mode.

[0154] The metal honeycomb body is the same as that of the first embodiment. The metal sheet and the brazing material are the same as those of the first embodiment.

[0155] A porous plug with an axial length of 10 mm was provided only on one end side (gas inlet side) of the hollow part of the winding core, and the plug shape maintenance, ignition performance and stable purification performance were evaluated in the same manner as in the first embodiment. The evaluation method was the same as in the first embodiment. In addition, the catalyst inflow prevention effect was not evaluated. The conditions other than the porous plug were the same as in the first embodiment.

[0156] However, in Comparative Example 7, a metal foil without through holes was used, and the core hollow portion was not sealed.

[0157] Regarding the mixing ratio of the metal sheet and the brazing material (X:Y), Example 6 is 5:5, Example 7 is 3:7, Example 8 is 4:6, Example 9 is 7:3, and Example 10 is 9:1.

[0158] In Comparative Example 6, the N plug of Comparative Example 3 was disposed only on one end side (gas inlet side) of the hollow portion of the winding core.

[0159] [Table 2]

[0160]

[0161]

[0162] Compared with Comparative Example 5 (see Table 1) which uses center shape processing as a limiting means, Examples 6 to 10 have improved shape maintenance of the plug. In addition, it can be seen that by setting X:Y to 7:3 or less, in other words, by setting X / Y to 7 / 3 or less, the desired bonding strength can be obtained and the shape maintenance of the plug can be improved. Compared with Comparative Example 6 using an N plug, Examples 6 to 10 have improved ignition performance. It can be seen 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 is increased, and the ignition performance is further improved.

[0163] In addition, Examples 6 to 10 are superior in stable purification performance compared to Comparative Example 4 (see Table 1), and the original purpose of the plug (restricting the inflow of exhaust gas into the hollow portion of the core and improving purification performance) can be maintained.

[0164] Furthermore, compared with Comparative Example 7 (no through-holes, unsealed), Examples 6 to 10 have excellent stable purification performance and equal or better ignition performance. Therefore, it can be seen that the porous plug can solve the problem of forming multiple through-holes on the metal foil (reduction in stable purification performance due to gas concentration in the hollow part of the core). In addition, it can be seen that by making the plug porous, the problem of providing a plug in the hollow part of the core can be solved (reduction in ignition performance).

[0165] The inventors of the present invention installed the porous plug of Example 8 in the hollow part of the axial core of a metal honeycomb body in which the diameter of the through hole of the metal foil was set to 8 mm, and conducted a test to investigate the stable purification performance while changing the opening ratio. In any case where the opening ratio was 20%, 30%, 40%, 50%, and 60%, the evaluation of the stable purification performance was A or AA.

[0166] In addition, a porous plug of Example 8 was placed in the hollow part of the axial core of a metal honeycomb body with an opening ratio of 20%, and a test was conducted to investigate the stable purification performance while changing the diameter of the through hole. In any case where the diameter of the through hole was 0.5 mm, 2 mm, or 4 mm, the stable purification performance was evaluated as AA.

[0167] (Third Embodiment)

[0168] The third example corresponds to the third implementation mode.

[0169] A metal honeycomb body without through holes formed in the metal foil is used. The other structures of the metal honeycomb body are the same as those of the first embodiment. The metal sheet and the brazing material are the same as those of the first embodiment.

[0170] Regarding the matching ratio (X:Y) of the metal sheet and the brazing material, Example 11 is 5:5, Example 12 is 3:7, Example 13 is 4:6, Example 14 is 7:3, Example 15 is 9:1, Comparative Example 8 is 1:9, and Comparative Example 9 is 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, the matching ratio of the metal sheet of Comparative Example 8 was too low, and none of the samples became plugged, so the porosity was not measured. The porosity was measured by the same method as the first embodiment.

[0171] In Comparative Example 10, an N plug is provided instead of a porous plug. The N plug uses the same material as the metal sheet of the porous plug. The axial length of the N plug is set to 10 mm, similarly to the porous plug of the embodiment. In Comparative Example 11, a porous plug and an N plug are not provided. In Comparative Example 12, the limiting portion (center shape processing) of Comparative Example 5 is provided.

[0172] A porous plug with an axial length of 10 mm was placed at both ends of the hollow part of the winding core, and the plug shape maintenance, ignition performance, catalyst inflow prevention effect and stable purification performance were evaluated. In addition, as a reference information, pressure loss was also evaluated.

[0173] The shape maintenance property of the plug and the catalyst inflow prevention effect were evaluated by the same method as in the first example.

[0174] Ignition performance is at SV (space velocity): 100,000h -1 The simulated gas was flowed into the metal honeycomb under the conditions of , and the gas temperature was gradually increased from room temperature. The HC conversion rate (%) at each temperature was measured, and the time (τ50) when the conversion rate reached 50% was used for evaluation based on the conversion rate-temperature curve. τ50 of 12 seconds or less was evaluated as AAA, 14 seconds or less was evaluated as AA, 16 seconds or less was evaluated as A, and more than 16 seconds was evaluated as B.

[0175] In addition, based on the conversion rate-temperature curve, the temperature (T80) when the conversion rate reaches 80% is set as AA when T80 is below 240°C, A when it is below 250°C, and B when it is above 250°C, thereby evaluating the stable purification performance. 3 H 6 ): 550ppm (1650ppmC), NO: 500ppm, CO: 0.5%, O 2 :1.5%、H 2 O: 10%, the rest is N 2 Simulated gas (simulated gas of diesel exhaust).

[0176] By drying at 25 °C N 2 Gas at 0.12Nm 3 / min flow rate into the metal honeycomb body, and the pressure difference before and after the metal honeycomb body is measured to evaluate the pressure loss. Compared with Comparative Example 11 (unsealed), if the difference is within ±1%, the pressure loss is low and evaluated as A, and if the difference exceeds 1%, the pressure loss is large and evaluated as B.

[0177] [Table 3]

[0178]

[0179]

[0180] Compared with Comparative Example 12 which uses center shape processing as a limiting means, Examples 11 to 15 have improved shape retention of the plug. In Comparative Example 9, the evaluation of shape retention of the plug is B because the brazing material is too little. In addition, it is known that by setting X:Y to 7:3 or less, in other words, by setting X / Y to 7 / 3 or less, the desired bonding strength can be obtained and the shape retention of the plug can be improved. Compared with Comparative Example 10 which uses an N plug, Examples 11 to 15 have improved ignition performance.

[0181] It is understood 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 is increased, and the ignition performance is further improved.

[0182] It is understood that by setting X:Y to 7:3 or less, in other words, by setting X / Y to 7 / 3 or less, the effect of preventing the inflow of the catalyst can be obtained.

[0183] In addition, compared with Comparative Example 11, Examples 11 to 15 have excellent stable purification performance and the same pressure loss as Comparative Example 11, and can also maintain the original purpose of the plug (to restrict the inflow of exhaust gas into the hollow part of the core and improve the purification performance without increasing the pressure loss).

[0184] (Fourth embodiment)

[0185] The fourth example corresponds to the fourth implementation mode.

[0186] A metal honeycomb body without through holes formed in the metal foil is used. The other structures of the metal honeycomb body are the same as those of the first embodiment. The metal sheet and the brazing material are the same as those of the first embodiment.

[0187] A porous plug with an axial length of 10 mm was placed at the end of the gas inlet side of the core hollow part to evaluate the plug shape maintenance, ignition performance, stable purification performance and pressure loss. However, in Example 21, the porous plug was placed at the end of the gas outlet side.

[0188] Regarding the matching ratio (X:Y) of the metal sheet and the brazing material, Example 16 is 5:5, Example 17 is 3:7, Example 18 is 4:6, Examples 19 and 21 are 7:3, Example 20 is 9:1, Comparative Example 13 is 1:9, and Comparative Example 14 is 9.5:0.5. Three samples were prepared for each of Examples 16 to 21 and Comparative Example 13, and the porosity was measured. However, the matching ratio of the metal sheet of Comparative Example 13 was too low, and none of the samples became plugged, so the porosity was not measured. The porosity was measured by the same method as in the first embodiment.

[0189] In Comparative Example 15, an N plug is provided instead of a porous plug. The N plug uses the same material as the metal sheet of the porous plug. The axial length of the N plug is set to 10 mm, similarly to the porous plug of the embodiment. In Comparative Example 16, a porous plug and an N plug are not provided. In Comparative Example 17, the limiting portion (center shape processing) of Comparative Example 5 is provided.

[0190] The shape maintenance property of the plug was evaluated by the same method as in the first example.

[0191] The light-off performance, steady-state purification performance, and pressure loss were evaluated by the same method as that of the third embodiment.

[0192] [Table 4]

[0193]

[0194] Compared with Comparative Example 17 which uses center shape processing as a limiting means, Examples 16 to 20 have improved shape retention of the plug. Comparative Example 14 has too little brazing material, so the evaluation of shape retention of the plug is B. In addition, it can be seen that by setting X:Y to 7:3 or less, in other words, by setting X / Y to 7 / 3 or less, the desired bonding strength can be obtained and the shape retention of the plug can be improved. Compared with Comparative Example 15 which uses an N plug, Examples 16 to 20 have improved ignition performance.

[0195] The performance obtained in Example 21 is the same as that in Example 19. It is understood 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 is increased, and the ignition performance is further improved.

[0196] In addition, compared with Comparative Example 16, Examples 16 to 20 have excellent stable purification performance and the same pressure loss as Comparative Example 16, and can also maintain the original purpose of the plug (to restrict the inflow of exhaust gas into the hollow part of the core and improve the purification performance without increasing the pressure loss).

[0197] (Variation Example)

[0198] In each of the above-mentioned embodiments, the metal sheet 31 and the brazing material are used as the 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 sheets 31 are bonded together by an inorganic adhesive is prepared in advance, and the porous plug 30 is arranged at one end or both ends of the winding core hollow part 6, and is bonded to the inner surface of the winding core hollow part 6 by an inorganic adhesive. For example, an inorganic adhesive containing aluminum oxide as a main component (for example, ARON CERAMIC D manufactured by Toagosei Co., Ltd.) can be used.

[0199] Explanation of symbols

[0200] 1: Catalytic converter;

[0201] 2: Flat foil;

[0202] 3: wave foil;

[0203] 4: Metal honeycomb;

[0204] 4a: through hole;

[0205] 5: Outer cylinder;

[0206] 6: Hollow part of the core;

[0207] 30: porous plug;

[0208] 31: Metal sheet.

Claims

1. A metal honeycomb body, comprising: a flat foil and a corrugated foil made of metal foil, which are wound around a predetermined axis; A plug made of a porous body is disposed at one end or both ends of the hollow portion of the winding core of the metal honeycomb body.

2. The metal honeycomb body according to claim 1, characterized in that: A plurality of through holes are formed in the flat foil and / or the corrugated foil.

3. The metal honeycomb body according to claim 1 or 2, characterized in that: The porous body has a structure in which a plurality of metal sheets are joined together using a brazing material.

4. The metal honeycomb body according to claim 3, characterized in that: The metal sheet is made of the same material as the metal foil, The brazing filler metal is made of the same material as the brazing filler metal used for bonding the flat foil and the corrugated foil.

5. The metal honeycomb body according to claim 1 or 2, characterized in that: The porous body includes a plurality of metal sheets and an inorganic adhesive for bonding adjacent metal sheets to each other.

6. The metal honeycomb body according to any one of claims 1 to 5, characterized in that The porosity of the porous body is 7% or more and 85% or less.

7. The metal honeycomb body according to any one of claims 1 to 6, characterized in that The porous bodies are arranged at both ends of the hollow part of the winding core of the metal honeycomb body. The porosity of the porous body is 70% or less.

8. The metal honeycomb body according to any one of claims 1 to 7, characterized in that The length of the porous body in the axial direction is not less than 1 time and not more than 3 times the diameter of the hollow portion of the winding core.

9. A honeycomb unit, characterized in that: include: The metal honeycomb body according to any one of claims 1 to 8; as well as The outer cylinder contains the metal honeycomb body.

10. A catalytic converter, wherein: A catalyst is supported on the metal honeycomb body according to any one of claims 1 to 8.

11. A catalytic converter, wherein: The metal honeycomb body of the honeycomb unit according to claim 9 supports a catalyst.

12. A method for manufacturing a honeycomb unit, the honeycomb unit comprising the metal honeycomb body according to claim 1 and an outer cylinder, the method for manufacturing the honeycomb unit comprising: a base material supplying step of supplying a slurry base material including a brazing material and a plurality of metal sheets from an end portion of the hollow portion of the winding core; as well as a firing step of firing the honeycomb unit after the base material supplying step, wherein a brazing material is pre-arranged at a predetermined position of the honeycomb unit to be subjected to the sintering step, The predetermined portion includes a predetermined joining portion between the flat foil and the corrugated foil, and a predetermined joining portion between the metal honeycomb body and the outer cylinder. In the base material supplying step, when the total content of the metal pieces contained in the slurry-like base material is X mass % and the total content of the brazing material is Y mass %, the ratio of X mass % to Y mass %, i.e., X:Y, is within the range of 3:7 to 9:

1.

13. The method for manufacturing a honeycomb unit according to claim 12, characterized in that: The base material supplying step is a step of supplying the slurry base material to both ends of the hollow portion of the winding core. X:Y is within the range of 3:7 to 7:3 inclusive.

14. A method for manufacturing a catalytic converter, characterized in that: After the sintering step described in claim 12 or 13, the following steps are performed: a catalyst slurry inflow step of causing a slurry containing a catalyst to flow in from an end portion in the axial direction of the honeycomb unit; and The catalyst loading step is to load the catalyst on the honeycomb unit by drying and firing the honeycomb unit after the catalyst slurry pouring step.

15. The method for manufacturing a honeycomb unit according to claim 12 or 13, characterized in that: A plurality of through holes are formed in the flat foil and / or the corrugated foil.

16. The method for manufacturing a catalytic converter according to claim 14, characterized in that: A plurality of through holes are formed in the flat foil and / or the corrugated foil.

17. A method for manufacturing a metal honeycomb body according to claim 1, characterized in that: include: a base material supplying step of supplying a slurry base material including a brazing material and a plurality of metal sheets from an end portion of the hollow portion of the winding core; as well as a firing step of firing the metal honeycomb body after the base material supplying step, In the base material supplying step, when the total content of the metal pieces contained in the slurry-like base material is set to X mass % and the total content of the brazing material is set to Y mass %, the ratio of X mass % to Y mass %, i.e., X:Y, is within the range of 3:7 to 9:

1.

18. A method for manufacturing a catalytic converter, characterized in that: After the sintering step described in claim 17, the following steps are performed: a catalyst slurry inflow step of causing a slurry containing a catalyst to flow into the metal honeycomb from an end portion in the axial direction; and The catalyst loading step is to load the catalyst on the metal honeycomb by drying and firing the metal honeycomb after the catalyst slurry flowing step.

19. The method for manufacturing a catalytic converter according to claim 18, characterized in that: A plurality of through holes are formed in the flat foil and / or the corrugated foil.

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