Electric heating 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 catalyst device.

Background Art

[0002] Patent Document 1 discloses an electrically heated catalyst device in which a carrier carrying a catalyst is electrically heated through a wiring member or the like from a battery, and a lead-out portion of the wiring member drawn out from an opening of an outer cylinder covering the outer peripheral surface of the carrier is formed in a bellows shape.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the electrically heated catalyst device disclosed in Patent Document 1, when overcurrent from the battery to the carrier occurs, there is a risk that the durability of the catalyst will decrease due to overheating of the catalyst.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide an electrically heated catalyst device capable of suppressing a decrease in the durability of the catalyst due to overheating when overcurrent to the carrier occurs.

Means for Solving the Problems

[0006] To solve the above-mentioned problems and achieve the objective, the electrically heated catalyst apparatus according to the present invention comprises a carrier on which a catalyst is supported, a surface electrode extending in the axial direction of the carrier on the outer circumferential surface of the carrier, a thin plate-shaped 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 circumferential surface of the carrier and having an opening on its side for pulling the wiring member outwards, wherein the wiring member is one end The wiring member has a first surface that contacts the surface electrode on one end and the terminal electrode on the other end, and a second surface on the opposite side of the first surface in the thickness direction of the wiring member, and the wiring member is characterized by having a first curved portion that extends from the one end and is bent so that the first surface side is convex, a second curved portion that extends from the first curved portion and is bent so that the second surface side is convex, and a wiring side joining surface portion that extends from the second curved portion and is joined to the terminal electrode.

[0007] This makes it possible to melt the wiring components at the intended location in the event of excessive current flow from the power supply to the carrier, thereby suppressing the reduction in catalyst durability due to overheating.

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

[0009] This makes it possible to press the first curved portion of the wiring member, which expands due to heat, toward the surface electrode when an overcurrent occurs from the power supply to the carrier, causing a short circuit between the vicinity of the first curved portion of the wiring member and the surface electrode, thereby melting the vicinity of the first curved portion of the wiring member.

[0010] Furthermore, in the above, the radius of curvature of the first curved section may be 1 [mm] or less.

[0011] This makes it easier to press the area near the first curve of the wiring component toward the surface electrode in the event of excessive current flow from the power supply to the carrier.

[0012] In the electrically heated catalyst device according to the present invention, when excessive current is supplied from the power supply to the carrier, it is possible to melt and cut the wiring member at the intended location, thereby suppressing the reduction in the durability of the catalyst due to overheating. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a cross-sectional view showing a schematic configuration of an electrically heated catalyst apparatus according to an embodiment. [Figure 2] Figure 2 is an enlarged cross-sectional view of the vicinity of the wiring member in the electrically heated catalyst device according to the embodiment. [Modes for carrying out the invention]

[0014] The following describes an embodiment of the electrically heated catalyst apparatus according to the present invention. However, the present invention is not limited to this embodiment.

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

[0016] The electrically heated catalytic converter 1 is installed, for example, in the exhaust path of an automobile, and purifies the exhaust gas discharged from the engine. As shown in Figure 1, the electrically heated catalytic converter 1 comprises a carrier 20 and an outer cylinder 70. Also as shown in Figure 1, the electrically heated catalytic converter 1 has surface electrodes 30, wiring members 40, and fixing members 50 on the carrier 20. Furthermore, the electrically heated catalytic converter 1 has a mat 60 between the carrier 20 and the outer cylinder 70.

[0017] The carrier 20 is a porous material that supports a catalyst such as platinum or palladium. Furthermore, since the carrier 20 itself is heated by electricity, it is made of a conductive ceramic, specifically, for example, SiC (silicon carbide). The carrier 20 has a roughly cylindrical outer shape and an internal honeycomb structure, through which the exhaust gas passes in the axial direction (y-axis direction) of the carrier 20.

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

[0019] The wiring members 40 are arranged on each of the surface electrodes 30. The wiring members 40 are made of thin stainless steel plates. The wiring members 40 are, for example, stainless steel foil electrodes having a comb-shaped first wiring section extending in the circumferential direction of the carrier on the surface electrode 30, a comb-shaped second wiring section extending in the axial direction of the carrier on the surface electrode 30, and a lead-out section 400 connected to the terminal electrode 81.

[0020] The plurality of first wiring portions extend in the circumferential direction of the carrier across the entire formation region of the surface electrode 30. Further, all the first wiring portions are connected to the lead-out portion 400 on the plus side in the z-axis direction of the formation region of the surface electrode 30. On the other hand, the plurality of first wiring portions are arranged in parallel on the surface electrode 30 at substantially equal intervals along the carrier axis direction. Also, the first wiring portions are arranged only at the central portion in the carrier axis direction of the surface electrode 30. The second wiring portion extends continuously from the two outermost first wiring portions in the carrier axis direction to the end of the surface electrode 30. Both the first wiring portion and the second wiring portion are fixed to the surface electrode 30 by the fixing member 50 and are electrically connected. On the other hand, the lead-out portion 400 is not fixed to the surface electrode 30 and is led out to the outside of the outer cylinder 70.

[0021] The fixing member 50 is a button-shaped sprayed film formed on the first wiring portion and the second wiring portion. By the fixing member 50, the first wiring portion and the second wiring portion are fixed to the surface electrode 30 and are electrically connected.

[0022] The mat 60 is a flexible heat insulating member. The mat 60 is wound around substantially the entire carrier 20. And the mat 60 is filled between the carrier 20 and the outer cylinder 70. By the mat 60, the carrier 20 is fixed and held to the outer cylinder 70. Also, the mat 60 plays a role of sealing the exhaust gas and not leaking it to the outside of the outer cylinder 70. The mat 60 is provided with openings for leading out the lead-out portions 400 of the wiring member 40 to the outside of the outer cylinder 70. The openings of the mat 60 are provided at two locations at the central portion in the axial direction of the carrier 20 corresponding to the formation positions of the respective lead-out portions 400.

[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 columnar 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 alloy. An opening for leading out the lead-out portion 400 of the wiring member 40 to the outside of the outer cylinder 70 is provided on the side surface of the outer cylinder 70.

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

[0025] FIG. 2 is an enlarged cross-sectional view of the vicinity of the wiring member 40 in the electric heating type catalyst device 1 according to the embodiment. In the electric heating type catalyst device 1 according to the embodiment, when overcurrent from the battery 83 to the carrier 20 occurs, by applying a force such that the first bent portion 41 of the wiring member 40 is pressed against the surface electrode 30 side by heat, the wiring member 43 is configured so that the fusing range in the wiring member 43 is defined near the first bent portion 41.

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

[0027] Note that the first bent portion 41 is formed in FIG. 2 so as to extend from the carrier 20 side to the opposite side of the tip of the terminal electrode 81 and then fold back to the tip side of the terminal electrode 81. Also, the second bent portion 42 is formed in FIG. 2 so as to extend from the first bent portion 41 to the tip side of the terminal electrode 81 and then fold back to the tip side of the terminal electrode 81.

[0028] In the electrically heated catalyst device 1 according to this embodiment, the first curved portion 41 of the wiring member 40 is configured to curve with a radius of curvature R1 (radius of curvature 1 [mm] or less) when the wiring-side joint surface portion 401 of the wiring member 40 and the electrode-side joint surface portion 811 of the terminal electrode 81 are joined. Furthermore, when the wiring-side joint surface portion 401 of the wiring member 40 and the electrode-side joint surface portion 811 of the terminal electrode 81 are joined, the second curved portion 432 is configured to be located on the opposite side of the electrode-side joint surface portion 811 of the terminal electrode 81 from the first curved portion 41 side (the lower side in Figure 2 and the negative side in the z-axis direction) in the thickness direction of the wiring member 40 at the joint portion 101 between the wiring member 40 and the terminal electrode 81. As a result, a force acts on the first curved portion 41 of the wiring member 40, pushing it in the positive side in the z-axis direction (upward side in Figure 2) via the second curved portion 42.

[0029] Furthermore, if excessive current flows from the battery 83 to the carrier 20, the high-temperature portion is transmitted to the negative z-axis side (downward in Figure 2) of the carrier 20, which is higher than the highest heat-generating portion 102 shown in Figure 2. As the high-temperature portion approaches the wiring member 40, the lead portion 400 of the wiring member 40 extends in the positive z-axis side (upward in Figure 2) due to the heat from the high-temperature portion. At this time, a force acts on the first curved portion 41 of the wiring member 40, pushing it in the positive z-axis side (upward in Figure 2) via the second curved portion 42, so that the area around the first curved portion 41 of the wiring member 40 is pressed towards the surface electrode 30. In particular, because the first curved portion 41 of the wiring member 40 is curved with a radius of curvature R1 (radius of curvature 1 [mm]) or less, the area around the first curved portion 41 of the wiring member 40 is more easily pressed towards the surface electrode 30. In this way, when the vicinity of the first curved portion 41 of the wiring member 40 is pressed toward the surface electrode 30, a potential difference occurs between the wiring member 40 and the surface electrode 30, which has a resistance several orders of magnitude greater than that of the wiring member 40. This causes a short circuit between the vicinity of the first curved portion 41 of the wiring member 40 facing the surface electrode 30 and the surface electrode 30, causing the vicinity of the first curved portion 41 of the wiring member 40 to melt. Alternatively, before the vicinity of the first curved portion 41 of the wiring member 40 melts due to such a short circuit, the lead portion 40 of the wiring member 40 may expand due to heat, causing the first curved portion 41 to bend. This reduces the current-carrying cross-sectional area at the first curved portion 41, which can lead to melting due to Joule heating near the first curved portion 41 of the wiring member 40. In either case, the wiring member 40 that has melted near the first curved portion 41 does not reach the outer cylinder 70, thus preventing leakage current.

[0030] In the electrically heated catalyst device 1 according to this embodiment, if excessive current is supplied from the battery 83 to the carrier 20, it is possible to melt and cut the wiring member 40 at the intended location, thereby suppressing a decrease in the durability of the catalyst due to overheating. [Explanation of symbols]

[0031] 1 Electrically heated catalyst device 20 carriers 30 surface electrode 40 Wiring components 40a Page 1 40b Page 2 41. Section 1 42 Part 2 50 fixed parts 60 マット 70 outer cylinder 101 Joint 102 Highest fever area 400 Introduction 401 Wiring Side Joint 811 Electrode side bonding face

Claims

[Claim 1] A support on which a catalyst is supported, A surface electrode extending in the axial direction of the carrier is provided on the outer circumferential surface of the carrier, A thin plate-shaped 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 that covers the outer surface of the carrier and has an opening on its side for pulling the wiring member outwards, An electrically heated catalyst device equipped with, The wiring member has a first surface that contacts the surface electrode at one end and the terminal electrode at the other end, and a second surface on the opposite side of the first surface in the thickness direction of the wiring member. The wiring member has a first curved portion extending from one end towards the other end, which is bent so that the first surface side is convex; a second curved portion extending from the first curved portion, which is bent so that the second surface side is convex; and a wiring-side joining surface portion extending from the second curved portion that is joined to the terminal electrode. The second curved portion is located in the thickness direction of the wiring member at the joint between the wiring member and the terminal electrode, and is positioned on the opposite side from the first curved portion with respect to the electrode-side joint surface of the terminal electrode that is joined to the wiring-side joint surface. An electrically heated catalyst device characterized in that the radius of curvature of the first curved portion is 1 [mm] or less.

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