Energization heating type catalyst device

Abstract

To provide an energization heating type catalyst device which can inhibit durability of a catalyst from being deteriorated by overheating when a carrier is excessively energized.SOLUTION: An energization heating type catalyst device of the invention includes: a carrier by which a catalyst is held; a surface electrode extended in an axial direction of the carrier on an outer peripheral surface of the carrier; a thin-plate-like wiring member which is fixed at one end to the surface electrode, electrically connected at the other end to a power supply device, and joined to a terminal electrode; and an outer cylinder which covers the outer peripheral surface of the carrier and has an opening for drawing the wiring member to the outside on its side surface. The wiring member has: a first surface which contacts with the surface electrode at one end side and contacts with the terminal electrode at the other end side; and a second surface opposite to the first surface in a thickness direction of the wiring member. The wiring member has, from the one end side to the other end side, a first bending part which extends from the one end and bends so as to protrude on the first surface side, a second bending part which extends from the first bending part and bends so as to protrude on the second surface side, and a wiring side joint surface part extending from the second bending part and joined to the terminal electrode.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an electrically heated catalytic converter. [Background technology]

[0002] Patent Document 1 discloses an electrically heated catalytic device in which a carrier carrying a catalyst is electrically heated from a battery via wiring members or the like, in which the lead-out portion of the wiring member that is drawn out from an opening in an outer tube that covers the outer peripheral surface of the carrier is formed in a bellows shape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-107452 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the electrically heated catalyst device disclosed in Patent Document 1, if an overcurrent occurs from the battery to the carrier, the catalyst may overheat and its durability may decrease.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide an electrically heated catalyst device that can prevent a decrease in the durability of the catalyst due to overheating when over-current occurs to the carrier. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the electrically heated catalytic device according to the present invention is an electrically heated catalytic device comprising: a carrier on which a catalyst is supported; a surface electrode extending in the axial direction of the carrier on the outer peripheral surface of the carrier; a thin-plate wiring member having one end fixed to the surface electrode and the other end joined to a terminal electrode electrically connected to a power supply device; and an outer cylinder covering the outer peripheral surface of the carrier and having an opening on a side for drawing out the wiring member to the outside, the wiring member being connected to the one end of the outer cylinder. the wiring member has a first surface that contacts the surface electrode at one end side and contacts the terminal electrode at the other end side, and a second surface opposite the first surface in a thickness direction of the wiring member, and the wiring member has a first curved portion extending from the one end side toward the other end side and bent so that the first surface side is convex, a second curved portion extending from the first curved portion and bent so that the second surface side is convex, and a wiring-side bonding surface portion extending from the second curved portion and bonded to the terminal electrode.

[0007] This makes it possible for the wiring member to melt at the intended location in the event of an overcurrent from the power supply device to the carrier, thereby preventing a decrease in the durability of the catalyst due to overheating.

[0008] In the above, the second curved portion may be positioned on the opposite side of the first curved portion in the thickness direction of the wiring member at the joint between the wiring member and the terminal electrode, with respect to the electrode side bonding surface portion that is bonded to the wiring side bonding surface portion of the terminal electrode.

[0009] As a result, if an overcurrent occurs from the power supply to the carrier, the first curved portion of the wiring member, which expands due to heat, is pressed toward the surface electrode, causing a short circuit between the first curved portion of the wiring member and the surface electrode, and melting the first curved portion of the wiring member.

[0010] In the above, the first curved portion may have a radius of curvature of 1 mm or less.

[0011] This makes it possible to easily press the vicinity of the first bent portion of the wiring member against the front electrode when overcurrent occurs from the power supply device to the carrier.

[0012] In the electrically heated catalyst device of the present invention, if an excessive current flows from the power supply device to the carrier, it is possible to melt the wiring member at the intended location, thereby preventing a decrease in the durability of the catalyst due to overheating. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic configuration of an electrically heated catalyst device according to an embodiment. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of the vicinity of a wiring member in the electrically heated catalyst device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electrically heated catalytic converter according to the present invention will be described below. However, the present invention is not limited to the embodiment.

[0015] 1 is a cross-sectional view showing a schematic configuration of an electrically heated catalytic device 1 according to an embodiment. The y-axis direction in the drawing is the axial direction of the carrier 20. When using the electrically heated catalytic device 1, it is preferable to align the positive z-axis direction with the vertical upward direction.

[0016] The electrically heated catalytic device 1 is provided, for example, on the exhaust path of an automobile or the like, and purifies exhaust gas discharged from the engine. As shown in Fig. 1, the electrically heated catalytic device 1 includes a carrier 20 and an outer casing 70. Also, as shown in Fig. 1, the electrically heated catalytic device 1 includes a surface electrode 30, a wiring member 40, and a fixing member 50 on the carrier 20. Furthermore, the electrically heated catalytic device 1 includes a mat 60 between the carrier 20 and the outer casing 70.

[0017] The support 20 is a porous member that supports a catalyst such as platinum or palladium. The support 20 itself is made of conductive ceramics, specifically, for example, SiC (silicon carbide), in order to be heated by electrical current. The support 20 has a generally cylindrical outer shape and a honeycomb structure inside, and exhaust gas passes through the inside of the support 20 in the axial direction of the support 20 (y-axis direction).

[0018] The surface electrodes 30 are electrodes (circumferential electrodes) formed on the outer peripheral surface of the carrier 20 along the circumferential direction, and are a pair of electrodes arranged opposite each other via the carrier 20. The surface electrodes 30 are in physical contact with the carrier 20 and are electrically connected to it. Each surface electrode 30 has a rectangular planar shape and extends in the carrier axial direction (y-axis direction). Furthermore, the surface electrodes 30 are electrically connected to a battery 83, which is a power supply device, via a wiring member 40, a terminal electrode 81, and an external wiring 82. With this configuration, a current is supplied from the battery 83 to the carrier 20, and the carrier 20 is electrically heated.

[0019] The wiring members 40 are disposed on the respective surface electrodes 30. The wiring members 40 are made of thin plate-like stainless steel. The wiring members 40 are, for example, stainless steel foil electrodes having a comb-tooth-shaped first wiring portion extending in the circumferential direction of the carrier on the surface electrode 30, a comb-tooth-shaped second wiring portion extending in the axial direction of the carrier on the surface electrode 30, and an extraction portion 400 connected to the terminal electrode 81.

[0020] The first wiring parts are arranged to extend in the circumferential direction of the carrier over the entire formation area of ​​the surface electrode 30. Furthermore, all the first wiring parts are connected to the lead-out part 400 on the positive side of the z-axis direction of the formation area of ​​the surface electrode 30. On the other hand, the first wiring parts are arranged in parallel on the surface electrode 30 at approximately equal intervals along the carrier axial direction. Moreover, the first wiring parts are arranged only in the center of the carrier axial direction of the surface electrode 30. The second wiring parts are arranged to extend from the two first wiring parts located on the outermost sides to the end of the surface electrode 30 in the carrier axial direction. Both the first wiring parts and the second wiring parts are fixed to the surface electrode 30 by the fixing member 50 and are electrically connected. On the other hand, the lead-out part 400 is not fixed to the surface electrode 30 and is led out to the outside of the outer tube 70.

[0021] The fixing member 50 is a button-shaped sprayed coating formed on the first wiring portion and the second wiring portion. The fixing member 50 fixes and electrically connects the first wiring portion and the second wiring portion to the surface electrode 30.

[0022] The mat 60 is a flexible heat insulating member. The mat 60 is wrapped around substantially the entire carrier 20. The mat 60 is filled between the carrier 20 and the outer tube 70. The mat 60 fixes and holds the carrier 20 to the outer tube 70. The mat 60 also seals the exhaust gas and prevents it from leaking out of the outer tube 70. The mat 60 has an opening for leading out the lead-out portion 400 of the wiring member 40 to the outside of the outer tube 70. The mat 60 has two openings in the axial center of the carrier 20, corresponding to the positions where the lead-out portions 400 are formed.

[0023] The outer cylinder 70 is a housing for housing the carrier 20, and is a pipe having a diameter slightly larger than that of the cylindrical carrier 20. The outer cylinder 70 covers substantially the entire carrier 20 via the mat 60. The outer cylinder 70 is preferably made of a metal such as a stainless steel alloy. An opening is provided on a side surface of the outer cylinder 70 for leading out the lead-out portion 400 of the wiring member 40 to the outside of the outer cylinder 70.

[0024] With the above-mentioned configuration, in the electrically heated catalyst device 1, the support 20 is electrically heated between the pair of surface electrodes 30, and the catalyst supported on the support 20 is activated. As a result, unburned HC (hydrocarbon), CO (carbon monoxide), NOx (nitrogen oxides), etc. in the exhaust gas passing through the support 20 are purified by catalytic reaction.

[0025] 2 is an enlarged cross-sectional view of the vicinity of the wiring member 40 in the electrically heated catalytic device 1 according to the embodiment. In the electrically heated catalytic device 1 according to the embodiment, the wiring member 43 is configured so that, when overcurrent occurs from the battery 83 to the carrier 20, a force is generated by heat to press the first bent portion 41 of the wiring member 40 toward the front electrode 30, thereby limiting the meltdown range of the wiring member 43 to the vicinity of the first bent portion 41.

[0026] The drawn-out portion 400 of the wiring member 40 has a first surface 40a that contacts the surface electrode 30 at one end side and contacts the terminal electrode 81 at the other end side, and a second surface 40b opposite to the first surface 40a in the thickness direction of the wiring member 40. The drawn-out portion 400 of the wiring member 40 has, from the one end (surface electrode 30) side toward the other end (terminal electrode 81) side, a first curved portion 41 that extends from the one end side and is bent so that the first surface 40a side is convex, a second curved portion 42 that extends from the first curved portion 41 and is bent so that the second surface 40b side is convex, and a wiring-side bonding surface portion 401 that extends from the second curved portion 42 and is bonded to an electrode-side bonding surface portion 811 of the terminal electrode 81.

[0027] 2, the first bending portion 41 is formed so as to extend from the carrier 20 side to the side opposite to the tip of the terminal electrode 81 and bend back to the tip side of the terminal electrode 81. Also, the second bending portion 42 is formed so as to extend from the first bending portion 41 to the tip side of the terminal electrode 81 and bend back to the tip side of the terminal electrode 81.

[0028] In the electrically heated catalytic device 1 according to the embodiment, the first bent portion 41 of the wiring member 40 is curved with a radius of curvature R1 (1 mm) or less when the wiring side joint surface 401 of the wiring member 40 and the electrode side joint surface 811 of the terminal electrode 81 are joined. In addition, when the wiring side joint surface 401 of the wiring member 40 and the electrode side joint surface 811 of the terminal electrode 81 are joined, the second bent portion 432 is positioned on the opposite side to the first bent portion 41 side (lower side in FIG. 2, negative side in the z-axis direction) with respect to the electrode side joint surface 811 of the terminal electrode 81 in the thickness direction of the wiring member 40 at the joint 101 between the wiring member 40 and the terminal electrode 81. As a result, a force is applied to the first bent portion 41 of the wiring member 40 in the z-axis direction positive side (upper side in FIG. 2) via the second bent portion 42.

[0029] When an overcurrent occurs from the battery 83 to the carrier 20, a high temperature portion is transferred to the negative side in the z-axis direction (lower side in FIG. 2) of the highest heat generating portion 102 of the carrier 20 shown in FIG. 2. When the high temperature portion approaches the wiring member 40, the drawn-out portion 400 of the wiring member 40 extends to the positive side in the z-axis direction (upper side in FIG. 2) due to heat from the high temperature portion. At this time, a force is applied to the first bent portion 41 of the wiring member 40 to push it to the positive side in the z-axis direction (upper side in FIG. 2) via the second bent portion 42, so that the vicinity of the first bent portion 41 of the wiring member 40 is pressed against the surface electrode 30. In particular, since the first bent portion 41 of the wiring member 40 is curved with a curvature radius R1 (curvature radius 1 [mm]) or less, the vicinity of the first bent portion 41 of the wiring member 40 is easily pressed against the surface electrode 30. In this way, when the vicinity of the first bent portion 41 of the wiring member 40 is pressed against the surface electrode 30, a short circuit occurs between the surface electrode 30 and the vicinity of the first bent portion 41 of the wiring member 40 facing the surface electrode 30 due to a potential difference between the wiring member 40 and the surface electrode 30, which has a resistance several orders of magnitude higher than that of the wiring member 40, and the vicinity of the first bent portion 41 of the wiring member 40 melts. In addition, before the vicinity of the first bent portion 41 of the wiring member 40 melts due to such a short circuit, the first bent portion 41 may be broken due to the extension of the drawn-out portion 400 of the wiring member 40 caused by heat, and the current-carrying cross-sectional area at the first bent portion 41 may become narrow, causing melting due to Joule heat to occur near the first bent portion 41 of the wiring member 40. In either case, the wiring member 40 whose vicinity of the first bent portion 41 has melted does not reach the outer tube 70, so that leakage current can be suppressed.

[0030] In the electrically heated catalytic converter 1 according to the embodiment, when an overcurrent occurs from the battery 83 to the carrier 20, it becomes possible for the wiring member 40 to melt at the intended location, thereby preventing the durability of the catalyst from decreasing due to overheating. [Explanation of symbols]

[0031] 1 Electrically heated catalyst device 20. Carrier 30 surface electrode 40 Wiring materials 40a Page 1 Second side of 40b First bent portion of 41 Second bent portion of 42 Fixing member of 50 Mat of 60 Outer cylinder of 70 Joint portion of 101 Highest heat generation portion of 102 Lead-out portion of 400 Wiring side joint surface portion of 401 Electrode side joint surface portion of 811

Claims

1. A support on which a catalyst is supported; a surface electrode extending in an axial direction of the carrier on an outer peripheral surface of the carrier; a thin-plate wiring member having one end fixed to the surface electrode and the other end joined to a terminal electrode electrically connected to a power supply device; an outer cylinder covering an outer peripheral surface of the carrier and having an opening on a side surface for drawing out the wiring member to the outside; An electrically heated catalytic converter comprising: the wiring member has a first surface that is in contact with the surface electrode at the one end and in contact with the terminal electrode at the other end, and a second surface that is opposite to the first surface in a thickness direction of the wiring member, The wiring member has, from the one end side toward the other end side, a first curved portion extending from the one end side and bent so that the first surface side is convex, a second curved portion extending from the first curved portion and bent so that the second surface side is convex, and a wiring side joining surface portion extending from the second curved portion and joined to the terminal electrode.

2. The electrically heated catalytic device according to claim 1, characterized in that the second curved portion is located on the opposite side of the first curved portion in the thickness direction of the wiring member at the joint between the wiring member and the terminal electrode, with respect to the electrode side joint surface portion that is joined to the wiring side joint surface portion of the terminal electrode.

3. 3. The electrically heated catalyst device according to claim 2, wherein the radius of curvature of the first curved portion is 1 mm or less.

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