Electrically heated carrier and exhaust gas purification device

Abstract

To provide an electric heating-type carrier which can improve the resistance of a metal electrode with respect to vibration, and an exhaust gas purification device.SOLUTION: An electric heating-type carrier of the present invention comprises a honeycomb structure having an outer peripheral wall and a bulkhead arranged inside the outer peripheral wall and defining and forming a plurality of cells which form a flow passage extending to the other end face from one end face, and a pair of metal electrodes 5 for applying a voltage to the honeycomb structure. Each of the pair of metal electrodes 5 has a connection part 50 fixed to an external peripheral face of the honeycomb structure, and a withdrawal part 51 extending from the connection part 50. At least two bent parts 510 are arranged at the withdrawal part, and extension directions of at least the two bent parts 510 differ from each other.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electrically heated carrier and an exhaust gas purification device. [Background technology]

[0002] In recent years, electrically heated catalysts (EHCs) have been proposed to improve the deterioration of exhaust gas purification performance immediately after engine start. EHCs are constructed by connecting metal electrodes to a columnar honeycomb structure made of conductive ceramics, and by passing electricity through the honeycomb structure itself, heating it up to the catalyst's activation temperature before the engine starts.

[0003] Patent Document 1 discloses the use of an electrode having an extraction portion with a bellows-like folded structure as an electrode for an electrically heated carrier. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5910620 Summary of the Invention [Problem to be solved by the invention]

[0005] The accordion-shaped folded structure described in Patent Document 1 is formed by folding the metal plate constituting the drawn-out portion multiple times along folding lines extending parallel to the axial direction of the carrier. As a result of the inventor's investigations, it became clear that this type of folded structure is excellent at absorbing stress against vibrations in the normal direction of the outer circumferential surface of the electrically heated carrier (the direction in which the drawn-out portion is compressed when the electrically heated carrier is inserted into the can body) and in the circumferential direction of the electrically heated carrier, but is vulnerable to vibrations in the axial direction of the electrically heated carrier. Therefore, the electrodes may be damaged when subjected to axial vibrations, and there is room for improvement.

[0006] The present invention has been made to solve the above-mentioned problems, and its object is to provide an electrically heated carrier and an exhaust gas purification device that can improve the resistance of a metal electrode to vibration. [Means for solving the problem]

[0007] The electrically heated carrier of the present invention comprises a honeycomb structure having an outer wall and partition walls arranged inside the outer wall to define a plurality of cells that form flow paths extending from one end face to the other end face, and a pair of metal electrodes for applying a voltage to the honeycomb structure, each of the pair of metal electrodes having a connection portion fixed to the outer surface of the honeycomb structure and a lead portion extending from the connection portion, and the lead portion has at least two bends, and the extension directions of the ridge lines of the at least two bends are different from each other.

[0008] The exhaust gas purification device according to the present invention includes the above-mentioned electrically heated carrier, and a metal can body that houses the electrically heated carrier and has an opening for pulling out the draw-out portion to the outside. [Effects of the Invention]

[0009] According to the electrically heated carrier and exhaust gas purification device of the present invention, the draw-out portion has at least two bent portions, and the extension directions of the ridge lines of the at least two bent portions are different from each other, thereby improving the resistance of the metal electrode to vibration. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view showing an exhaust gas purification device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of the exhaust gas purification device taken along line II-II in FIG. [Figure 3] FIG. 3 is a perspective view showing the metal electrode of FIG. 2. [Figure 4] FIG. 5 is a perspective view showing an exhaust gas purification device according to a second embodiment of the present invention. [Figure 5]FIG. 5 is a cross-sectional view of the exhaust gas purification device taken along line VV in FIG. [Figure 6] FIG. 6 is a perspective view showing the metal electrode of FIG. 5. [Figure 7] FIG. 10 is a perspective view showing a metal electrode of an exhaust gas purification device according to a third embodiment of the present invention. [Figure 8] FIG. 10 is a perspective view showing a metal electrode of an exhaust gas purification device according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention is not limited to the embodiments, and the components can be modified and embodied without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in each embodiment. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined.

[0012] Embodiment 1 Fig. 1 is a perspective view showing an exhaust gas purification device 1 according to a first embodiment of the present invention, and Fig. 2 is a cross-sectional view of the exhaust gas purification device 1 taken along line II-II in Fig. 1. The exhaust gas purification device 1 shown in Figs. 1 and 2 is provided in an exhaust path of, for example, an automobile, etc., and is a device for purifying exhaust gas emitted from an engine.

[0013] As shown in FIGS. 1 and 2, the exhaust gas purification device 1 has an electrically heated carrier 2 and a can body 3.

[0014] The electrically heated carrier 2 has a honeycomb structure 4 and a pair of metal electrodes 5. The honeycomb structure 4 is a columnar ceramic member and has an outer peripheral wall 40 and partition walls 41 disposed inside the outer peripheral wall 40 to define a plurality of cells 41a that form flow paths extending from one end face to the other end face. The columnar shape can be understood as a three-dimensional shape having a thickness in the flow path direction of the cells 41a (axial direction of the honeycomb structure 4). The ratio (aspect ratio) of the axial length of the honeycomb structure 4 to the diameter or width of the end face of the honeycomb structure 4 is arbitrary. The columnar shape may also include a shape (flat shape) in which the axial length of the honeycomb structure 4 is shorter than the diameter or width of the end face.

[0015] The outer shape of the honeycomb structure 4 is not particularly limited as long as it is columnar, and may be other shapes such as a columnar shape with circular end faces (cylindrical shape), a columnar shape with oval end faces, a columnar shape with polygonal end faces (quadragonal, pentagonal, hexagonal, heptagonal, octagonal, etc.), etc. The size of the honeycomb structure 4 is set to 2000 to 20000 mm2 in order to increase heat resistance (suppress cracks in the circumferential direction of the outer peripheral wall). 2 It is preferable that the thickness is 5000 to 15000 mm 2 It is more preferable that:

[0016] Although there is no limitation on the shape of the cells 41a in a cross section perpendicular to the flow direction, a square, a hexagon, an octagon, or a combination thereof is preferable. Among these, a square and a hexagon are preferable. By using such a cell shape, the pressure loss when exhaust gas flows through the honeycomb structure 4 is reduced, and the purification performance of the catalyst is improved.

[0017] The thickness of the partition walls 41 that define the cells 41a is preferably 0.1 to 0.3 mm, and more preferably 0.1 to 0.2 mm. When the thickness of the partition walls 41 is 0.1 mm or more, it is possible to prevent a decrease in the strength of the honeycomb structure 4. When the thickness of the partition walls 41 is 0.3 mm or less, it is possible to prevent an increase in pressure loss when exhaust gas flows through the honeycomb structure 4 when the honeycomb structure 4 is used as a catalyst carrier and a catalyst is loaded thereon. In the present invention, the thickness of the partition walls 41 is defined as the length of a portion that passes through the partition walls 41, of a line segment that connects the centers of gravity of adjacent cells 41a in a cross section perpendicular to the flow path direction of the cells 41a.

[0018] The honeycomb structure 4 has a cell density of 40 to 150 cells / cm in a cross section perpendicular to the flow path direction of the cells 41a. 2 It is preferable that the number of cells is 70 to 100. 2 By setting the cell density in this range, it is possible to increase the purification performance of the catalyst while minimizing the pressure loss when exhaust gas flows through it. 2 If the cell density is 150 cells / cm or more, a sufficient catalyst carrying area is ensured. 2 When the honeycomb structure 4 is used as a catalyst carrier and a catalyst is carried thereon, excessive pressure loss during the flow of exhaust gas is suppressed if the honeycomb structure 4 is used as a catalyst carrier and the cell density is a value obtained by dividing the number of cells by the area of ​​one end face portion of the honeycomb structure 4 excluding the outer wall 40 portion.

[0019] Providing the peripheral wall 40 of the honeycomb structure 4 is useful from the viewpoint of ensuring the structural strength of the honeycomb structure 4 and suppressing leakage of the fluid flowing through the cells 41a from the peripheral wall 40. Specifically, the thickness of the peripheral wall 40 is preferably 0.05 mm or more, more preferably 0.10 mm or more, and even more preferably 0.15 mm or more. However, if the peripheral wall 40 is made too thick, the strength becomes too high, which disrupts the strength balance with the partition walls 41 and reduces thermal shock resistance. Therefore, the thickness of the peripheral wall 40 is preferably 1.0 mm or less, more preferably 0.7 mm or less, and even more preferably 0.5 mm or less. Here, the thickness of the peripheral wall 40 is defined as the thickness in the direction normal to the tangent of the peripheral wall 40 at the measurement point when the portion of the peripheral wall 40 to be measured is observed in a cross section perpendicular to the flow path direction of the cells 41a.

[0020] The honeycomb structure 4 is preferably made of ceramics and has electrical conductivity. There are no particular restrictions on the volume resistivity of the honeycomb structure 4 as long as it can generate heat by Joule heat when electrified, but it is preferably 0.1 to 200 Ωcm, and more preferably 1 to 200 Ωcm. In the present invention, the volume resistivity of the honeycomb structure 4 is a value measured at 25°C by a four-terminal method.

[0021] The material of the honeycomb structure 4 is not limited, but can be selected from the group consisting of oxide ceramics such as alumina, mullite, zirconia, and cordierite, and non-oxide ceramics such as silicon carbide, silicon nitride, and aluminum nitride. Silicon carbide-metal silicon composites and silicon carbide / graphite composites can also be used. Among these, from the viewpoint of achieving both heat resistance and electrical conductivity, the material of the honeycomb structure 4 preferably contains a silicon-silicon carbide composite or a ceramic containing silicon carbide as the main component. When the material of the honeycomb structure 4 is said to contain a silicon-silicon carbide composite as the main component, it means that the honeycomb structure 4 contains 90 mass% or more of the silicon-silicon carbide composite (total mass) of the entire structure. Here, the silicon-silicon carbide composite material contains silicon carbide particles as aggregate and silicon as a binder that bonds the silicon carbide particles, and it is preferable that a plurality of silicon carbide particles are bonded by the silicon so as to form pores between the silicon carbide particles. When the material of the honeycomb structure 4 is said to be mainly composed of silicon carbide, it means that the honeycomb structure 4 contains silicon carbide (total mass) in an amount of 90 mass% or more of the entire material.

[0022] When the honeycomb structure 4 contains a silicon-silicon carbide composite material, the ratio of the "mass of silicon as a binder" contained in the honeycomb structure 4 to the sum of the "mass of silicon carbide particles as aggregate" contained in the honeycomb structure 4 and the "mass of silicon as a binder" contained in the honeycomb structure 4 is preferably 10 to 40 mass%, and more preferably 15 to 35 mass%.

[0023] The partition walls 41 may be porous. If they are porous, the porosity of the partition walls 41 is preferably 35 to 60%, and more preferably 35 to 45%. The porosity is a value measured with a mercury porosimeter. The partition walls 41 may also be dense, and if they are dense, the porosity of the partition walls 41 may be 10% or less, or 5% or less.

[0024] The average pore diameter of the partition walls 41 of the honeycomb structure 4 is preferably 2 to 15 μm, and more preferably 4 to 8 μm. The average pore diameter is a value measured by a mercury porosimeter.

[0025] Although not shown, the honeycomb structure 4 has an electrode layer provided on the outer surface of the peripheral wall 40. The electrode layer is provided, for example, as a pair of electrode layers extending in a band shape in the flow path direction of the cells 41a on the outer surface of the peripheral wall 40, sandwiching the central axis of the honeycomb structure 4 therebetween. However, the arrangement of the electrode layers is not limited to this form as long as they can be connected to a pair of metal electrodes 5 described below. A pair of metal electrodes 5 is provided on these electrode layers, and the electrode layers and the metal electrodes 5 are connected. Although not shown, an external power source such as a battery can be connected to the metal electrodes 5 via a power cable. The honeycomb structure 4 can generate heat by applying a voltage to the honeycomb structure 4 through the metal electrodes 5 and the electrode layers.

[0026] From the viewpoint of making it easier for electricity to flow through the electrode layers, the volume resistivity of the electrode layers is preferably 1 / 200 or more and 1 / 10 or less of the volume resistivity of the honeycomb structure 4 .

[0027] The electrode layer may be made of conductive ceramics, metals, or composites (cermets) of metals and conductive ceramics. Metals include, for example, Cr, Fe, Co, Ni, Si, or Ti, or alloys containing at least one metal selected from the group consisting of these metals. Conductive ceramics include, but are not limited to, silicon carbide (SiC), and metal compounds such as metal silicides, including tantalum silicide (TaSi2) and chromium silicide (CrSi2).

[0028] The honeycomb structure 4 having electrode layers is manufactured by first applying an electrode layer forming raw material containing ceramic raw materials to the side surface of a dried honeycomb body and drying the applied material to form a pair of unfired electrode layers extending in a band-like shape in the flow path direction of the cells on the outer surface of the peripheral wall, sandwiching the central axis of the dried honeycomb body. Next, the dried honeycomb body with unfired electrode layers is fired to manufacture a fired honeycomb body having a pair of electrode layers. This produces the honeycomb structure 4 having electrode layers.

[0029] The pair of metal electrodes 5 is used to apply a voltage to the honeycomb structure 4. The pair of metal electrodes 5 is attached to the outer peripheral surface of the honeycomb structure 4, more specifically, on the electrode layer. The pair of metal electrodes 5 is arranged spaced apart from each other in the circumferential direction of the honeycomb structure 4. The pair of metal electrodes 5 may be arranged at the center in the axial direction of the honeycomb structure 4, or may be arranged at a position shifted from the center in the axial direction. One of the pair of metal electrodes 5 is treated as an anode, and the other is treated as a cathode. In other words, a current flows from one metal electrode 5 through the honeycomb structure 4 to the other metal electrode 5.

[0030] Each of the pair of metal electrodes 5 has a connection portion 50 fixed to the outer peripheral surface of the honeycomb structure 4 and a lead portion 51 extending from the connection portion 50. The connection portion 50 is in contact with and connected to the outer peripheral surface of the honeycomb structure 4. An external power source can be connected to the lead portion 51 via a power cable (not shown). Details of the connection portion 50 and the lead portion 51 will be described later with reference to the drawings.

[0031] By supporting a catalyst on the electrically heated support 2, the electrically heated support 2 can be used as a catalyst body. Examples of the catalyst include precious metal catalysts and other catalysts. Precious metal catalysts include three-way catalysts and oxidation catalysts in which a precious metal such as platinum (Pt), palladium (Pd), or rhodium (Rh) is supported on the surface of alumina pores and a promoter such as ceria or zirconia is included, or alkaline earth metals and platinum are used to produce nitrogen oxides (NO x ) as a storage component of NOx Examples of catalysts that do not use precious metals include NOx storage reduction catalysts (LNT catalysts) containing copper-substituted or iron-substituted zeolites. x Examples include selective catalytic reduction catalysts (SCR catalysts). Two or more catalysts selected from these catalysts may be used. There are no particular limitations on the method for supporting the catalyst, and the method can be carried out in accordance with the conventional method for supporting a catalyst on a honeycomb structure.

[0032] The can body 3 is a cylindrical metal member for accommodating the electrically heated carrier 2. The can body 3 has an opening 30 for drawing out the draw-out portion 51 to the outside. Examples of metals include various stainless steels such as chromium-based stainless steel. An insulating layer made of glass can be provided on the inner peripheral surface of the can body 3. By providing the insulating layer, the effect of preventing electrical leakage when current is applied to the electrically heated carrier 2 can be further improved. Although not shown in the figure, a mat may be inserted between the outer peripheral surface of the honeycomb structure 4 and the inner peripheral surface of the can body 3.

[0033] Next, Fig. 3 is a perspective view showing the metal electrode 5 of Fig. 2. The metal electrode 5 of this embodiment is made up entirely of a single metal plate, and the connection portion 50 and the lead portion 51 are integrally formed with each other.

[0034] The connecting portion 50 has an overall comb-like outer shape. More specifically, the connecting portion 50 has a longitudinal base portion 500 and a plurality of teeth 501 extending parallel to one another from one side edge of the base portion 500 and spaced apart from one another in the longitudinal direction of the base portion 500. Each tooth 501 extends in a direction perpendicular to the longitudinal direction of the base portion 500.

[0035] The lead-out portion 51 is formed by bending a metal piece extending from the connection portion 50. More specifically, the lead-out portion 51 is formed by bending a metal piece extending from a side edge of the base portion 500 opposite to the side edge from which the tooth portion 501 extends. The metal piece constituting the lead-out portion 51 may extend from a center portion of the base portion 500 in the longitudinal direction of the base portion 500 in a direction perpendicular to the longitudinal direction of the base portion 500. The metal piece constituting the lead-out portion 51 may also extend from a position shifted in the longitudinal direction of the base portion 500 from the center portion of the base portion 500 in the longitudinal direction of the base portion 500.

[0036] The lead-out portion 51 is provided with at least two bent portions 510. The lead-out portion 51 of the present embodiment is provided with two bent portions 510. However, the number of bent portions 510 may be three or more. The at least two bent portions 510 are formed so that the extending directions of their respective ridge lines R are different from each other. The ridge line R is a line along which the apex of the bent portion 510 that appears on the outer side of the bent portion 510 extends, and can also be understood as a bending line when forming the bent portion 510.

[0037] Each part of the lead-out portion 51 can rotate around an axis that is the extension direction of the ridge line R of the bent portion 510. The lead-out portion 51 can expand and contract as each part rotates. As described above, since the extension directions of at least two bent portions 510 are different from each other, the rotation directions of each part connected by those bent portions 510 are also different from each other. This allows each part to rotate in more directions than when all bent portions 510 extend in the same direction, and the resistance of the metal electrode 5 to vibration can be improved.

[0038] More specifically, the lead-out portion 51 of the present embodiment is provided with first and second bent portions 511, 512 (two bent portions 510) and first and second plate portions 513, 514. The first bent portion 511 is provided between the base portion 500 and the first plate portion 513 of the connection portion 50. A ridge line R of the first bent portion 511 extends in the longitudinal direction of the base portion 500 of the connection portion 50. The second bent portion 512 is provided between the first plate portion 513 and the second plate portion 514. The second bent portion 512 is disposed on the tip side of the first plate portion 513. The ridge line R of the second bent portion 512 extends in a direction perpendicular to the ridge line R of the first bent portion 511. The angle at which the ridge line R of the first bent portion 511 and the ridge line R of the second bent portion 512 intersect may be less than 90° or greater than 90°. However, from the viewpoint of stress buffering (vibration absorption), the angle at which the ridgeline R of first bent portion 511 and the ridgeline R of second bent portion 512 intersect is preferably close to 90° (perpendicular), and this angle is preferably 90±45°, more preferably 90±30°, and even more preferably 90±15°. Note that when the ridgeline R of first bent portion 511 and the ridgeline R of second bent portion 512 are in a twisted relationship, the angle at which these ridgelines R intersect may be understood to be the intersection angle when one of the ridgelines R is moved in parallel so as to intersect with the other.

[0039] For ease of explanation, mutually orthogonal X, Y, and Z axes are defined as shown in Fig. 3. The X axis can be understood as an axis extending in the direction in which the tooth portion 501 extends from the base 500 of the connecting portion 50, the Y axis as an axis extending in the longitudinal direction of the base 500 of the connecting portion 50, and the Z axis as an axis extending in the thickness direction of the base 500.

[0040] When the connecting portion 50 is fixed to the outer peripheral surface of the honeycomb structure 4, the first plate portion 513 can rotate around the Y axis. That is, the first plate portion 513 can be displaced in the X and Z axis directions. This means that the first bent portion 511 can absorb vibrations in the X and Z axis directions. Furthermore, the second plate portion 514 can rotate around an axis located on a plane defined by the X and Z axes. That is, the second plate portion 514 can be displaced at least in the Y axis direction. This means that the second bent portion 512 can absorb vibrations in at least the Y axis direction. In other words, it can be seen that the draw-out portion 51 of this embodiment can absorb vibrations in all three axis directions.

[0041] The extension directions of the ridge lines R of the at least two bent portions 510 can include a first direction parallel to the axial direction of the honeycomb structure 4 and a second direction perpendicular to the first direction. As shown in Fig. 1 and Fig. 2, by arranging the metal electrode 5 so that the longitudinal direction of the base portion 500 of the connection portion 50 is parallel to the axial direction of the honeycomb structure 4, it is possible to make the ridge lines R of the first bent portions 511 extend in the first direction. However, other arrangements may be adopted, such as inclining the extension direction of the ridge lines R of the bent portions 510 at an angle of less than 90° with respect to the axial direction of the honeycomb structure 4.

[0042] The thickness of the lead-out portion 51 is preferably 0.03 mm or more and 1 mm or less. When the thickness of the lead-out portion 51 is 0.03 mm or more, the strength of the lead-out portion 51 is sufficiently ensured. When the thickness of the lead-out portion 51 is 1 mm or less, the rigidity of the lead-out portion 51 is not too high, the lead-out portion 51 easily expands and contracts, and vibrations are more easily absorbed. The thickness of the lead-out portion 51 is more preferably 0.03 mm or more and 0.8 mm or less, and even more preferably 0.05 mm or more and 0.7 mm or less. By setting the thickness of the lead-out portion 51 within the above range, the lead-out portion 51 can smoothly expand and contract while ensuring sufficient strength. The thickness of the connection portion 50 may be the same as or different from the thickness of the lead-out portion 51.

[0043] The material of the metal electrode 5 is preferably an alloy containing at least one selected from the group consisting of Cr, Fe, Co, Ni and Ti, and more preferably stainless steel or an Fe—Ni alloy.

[0044] In the electrically heated carrier 2 and exhaust gas purification device 1 of this embodiment, at least two bent portions 510 are provided in the draw-out portion 51, and the extension directions of the ridge lines R of the at least two bent portions 510 are different from each other, thereby improving the resistance of the metal electrode 5 to vibration.

[0045] Furthermore, the thickness of the lead-out portion 51 is not less than 0.03 mm and not more than 1 mm, so that the lead-out portion 51 can smoothly expand and contract while ensuring sufficient strength.

[0046] Furthermore, the extension direction of the ridge lines R of at least two bends 510 includes a first direction parallel to the axial direction of the honeycomb structure 4 and a second direction perpendicular to the first direction, so that the resistance of the metal electrode 5 to vibrations that are expected to be applied when the electrically heated carrier 2 and the exhaust gas purification device 1 are mounted on a vehicle can be more reliably improved.

[0047] Embodiment 2 FIG. 4 is a perspective view showing an exhaust gas purification device 1 according to embodiment 2 of the present invention, FIG. 5 is a cross-sectional view of the exhaust gas purification device 1 along line VV in FIG. 4, and FIG. 6 is a perspective view showing the metal electrode 5 in FIG. 5.

[0048] As shown in FIGS. 4 to 6, the lead portion 51 of the metal electrode 5 of the second embodiment is formed by bending a metal piece extending in the longitudinal direction from one end of the base portion 500 in the longitudinal direction. The ridge line R of the first bent portion 511 of the lead portion 51 extends in a direction perpendicular to the longitudinal direction of the base portion 500. The ridge line R of the second bent portion 512 of the lead portion 51 extends in the longitudinal direction of the base portion 500. That is, in the second embodiment, the bending order of the first and second bent portions 511, 512 is reversed from that in the first embodiment. The other configurations are the same as those in the first embodiment.

[0049] In this way, the bending order of the bending portions 510 of the lead-out portion 51 may be changed arbitrarily.

[0050] Embodiment 3 FIG. 7 is a perspective view showing a metal electrode 5 of an exhaust gas purification device 1 according to a third embodiment of the present invention. As shown in FIG. 7, the metal electrode 5 may be composed of a plurality of metal plates. The metal electrode 5 of this embodiment has a first metal plate 6 and a second metal plate 7. The first and second metal plates 6, 7 each have a connection portion 50 and a lead portion 51. That is, the metal electrode 5 of this embodiment has a plurality of connection portions 50 and a plurality of lead portions 51.

[0051] The electrically heated carrier 2 according to the third embodiment has a pair of metal electrodes 5, similar to the electrically heated carrier 2 according to the first embodiment. The pair of metal electrodes 5 can be the metal electrodes 5 shown in Fig. 7. That is, the pair of metal electrodes 5 in the electrically heated carrier 2 according to the third embodiment each have a plurality of connection portions 50 and a plurality of lead portions 51.

[0052] The first and second metal plates 6, 7 are arranged so that the base portions 500 and the lead portions 51 of the respective connection portions 50 overlap each other. The tooth portions 501 of the connection portions 50 of the first and second metal plates 6, 7 extend in opposite directions from the respective base portions 500. The configuration of the lead portions 51 of the first and second metal plates 6, 7 is the same as that of the second embodiment. However, the bending angles of the respective bent portions 510 are appropriately adjusted so that the lead portions 51 of the first and second metal plates 6, 7 are in surface contact with each other over their entirety. The other configurations are the same as those of the first and second embodiments.

[0053] Embodiment 4 FIG. 8 is a perspective view showing the metal electrode 5 of the exhaust gas purification device 1 according to the fourth embodiment of the present invention. In the third embodiment (FIG. 7), the lead portions 51 of the first and second metal plates 6, 7 are described as being in surface contact with each other over the entire surface, but the lead portions 51 of the first and second metal plates 6, 7 do not have to be in surface contact with each other. Vibrations can be absorbed even if the lead portions 51 are not in surface contact with each other. In the embodiment shown in FIG. 8, the bent portions 510 located on the outside of the bend and the bent portions 510 located on the inside of the bend have different radii of curvature so that they are not in contact with each other. The rest of the configuration is the same as in the first to third embodiments. [Example]

[0054] The inventors conducted a vibration test using a plurality of stainless steel metal electrodes 5, each having a plurality of teeth 501 as shown in FIG. 3 . The plurality of metal electrodes 5 were designed so that the shape of the bent portions 510 in the lead portions 51 and the thickness of the lead portions 51 were different from one another, as shown in the table below. In the table below, a metal electrode 5 having two bent portions 510, but with the ridge lines R of the two bent portions 510 extending in the same direction, is designated as a comparative example, and a metal electrode 5 having two bent portions 510 with the ridge lines R extending in different directions is designated as an example. The comparative example is a metal electrode 5 having an accordion-shaped lead portion 51 (with the ridge lines R of the two bent portions 510 extending in the same direction) formed by simply folding a longitudinal metal piece twice.

[0055] In the vibration test, the tip portion of the tooth portion 501 (the portion farther from the base portion 500) was joined to a ceramic test piece sample, and a terminal for external connection was fastened to the tip of the lead portion 51 with a nut. Furthermore, simple harmonic motion in the X-axis direction and the Y-axis direction shown in FIG. 3 was applied to the workpiece (the test piece sample and the metal electrode 5). The vibration frequency was 150 Hz, the vibration acceleration was 40 G, and the simple harmonic motion time was 2 hours. Ten metal electrodes 5 were used for each simple harmonic motion in each axial direction. The joint between the tip portion of the tooth portion 501 and the test piece sample and the bent portion 510 were then examined for fracture. Fracture at the joint included separation between the tip portion of the tooth portion 501 and the test piece sample. The results of the examination are shown in the table below.

[0056] [Table 1]

[0057] For example, comparing the total number of fractured samples between Comparative Example 1 and Example 1, which have the same thickness of the lead portion 51, shows that metal electrodes 5 having ridge lines R extending in different directions are less likely to fracture than metal electrodes 5 having ridge lines R extending in the same direction. In particular, it can be seen that in the Example, fracture of the joint when vibration in the Y-axis direction is applied is suppressed. This is thought to be because the metal electrode 5 of the Example is provided with the second bent portion 512, which allows it to absorb vibration in the Y-axis direction. This shows the advantage of providing at least two bent portions 510 in the lead portion 51, whose ridge lines R extend in different directions.

[0058] By comparing Comparative Example 1-6 with Example 1-6, it is clear that the number of breakages is suppressed when the thickness of at least the drawn-out portion 51 is 0.03 mm or more and 0.8 mm or less. [Explanation of symbols]

[0059] 1: Exhaust gas purification device 2: Electrically heated carrier 3:Can body 30:Aperture 4: Honeycomb structure 40: Outer wall 41: Bulkhead 41a: Cell 5: Metal electrode 50: Connection part 51:Drawer part 510: Bend R: Ridgeline

Claims

1. a honeycomb structure having an outer peripheral wall and partition walls disposed inside the outer peripheral wall and defining a plurality of cells that form flow paths extending from one end face to the other end face; a pair of metal electrodes for applying a voltage to the honeycomb structure; Equipped with Each of the pair of metal electrodes is a connecting portion fixed to the outer peripheral surface of the honeycomb structure; a lead portion extending from the connection portion; It has The lead-out portion has at least two bent portions, The extension directions of the ridge lines of the at least two bent portions are different from each other. Electrically heated carrier.

2. The thickness of the pull-out portion is 0.03 mm or more and 1 mm or less.

2. An electrically heated carrier according to claim 1.

3. Each of the pair of metal electrodes has a plurality of the connection portions and a plurality of the lead portions extending from the connection portions.

3. An electrically heated carrier according to claim 1 or 2.

4. The extension directions of the ridge lines of the at least two bent portions include a first direction parallel to the axial direction of the honeycomb structure and a second direction perpendicular to the first direction.

4. An electrically heated carrier according to any one of claims 1 to 3.

5. the honeycomb structure has a pair of electrode layers provided on the outer surface of the outer wall, on either side of a central axis of the honeycomb structure, so as to extend in a band shape in a flow path direction of the cells, the pair of metal electrodes are connected to the electrode layer; 5. An electrically heated carrier according to any one of claims 1 to 4.

6. An electrically heated carrier according to any one of claims 1 to 5; a metal can body that accommodates the electrically heated carrier and has an opening for pulling out the drawer portion to the outside; Equipped with Exhaust gas purification device.

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