Electric heating catalyst device

Abstract

To suppress the formation of an electrical leak path with condensed water that is produced during cold time.SOLUTION: An electric heating catalyst device comprises a base material which generates heat upon application of electricity to it, and a pair of electrode terminals electrically connected to the base material. A catalyst carried on the base material is heated by the application of a voltage to the base material by the pair of electrode terminals via the base material. The pair of electrode terminals are rod electrodes, which are arranged on the upper side in the vertical direction relative to the center axis of the base material and extend in a direction which is inclined to a horizontal face including the center axis of the base material.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 provided in the exhaust passage of an internal combustion engine, which comprises a substrate that supports a catalyst and a pair of electrodes attached to the substrate, and which heats the catalyst by applying a voltage from the electrodes to the substrate, causing the substrate to generate heat. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-116775 Summary of the Invention [Problem to be solved by the invention]

[0004] In an electrically heated catalytic converter, the case that houses the substrate is sealed so that exhaust gas does not leak from the case to the outside of the exhaust passage, and the substrate and the electrodes are electrically connected inside the case. However, when the case is cold, condensed water is generated inside the case, and if the condensed water comes into contact with an electrically conductive part such as an electrode, there is a risk that a leakage path will be formed in which the electrically conductive part such as the electrode and the case are electrically connected via the condensed water.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide an electrically heated catalyst device that can suppress the formation of a leakage path caused by condensed water that occurs when the vehicle is cold. [Means for solving the problem]

[0006] The present invention is an electrically heated catalyst device comprising a substrate that generates heat when electricity is passed through it, and a pair of electrode terminals electrically connected to the substrate, in which a catalyst supported on the substrate is heated via the substrate when the pair of electrode terminals apply a voltage to the substrate, and is characterized in that the pair of electrode terminals are rod-shaped electrodes that are positioned vertically above the central axis of the substrate and extend in a direction inclined relative to a horizontal plane including the central axis of the substrate.

[0007] According to this configuration, since the electrode terminal is disposed vertically above the central axis of the base material, it is possible to prevent condensed water generated during cold conditions from coming into contact with the electrode terminal. This makes it possible to prevent the formation of a leakage path due to condensed water. In addition, since the electrode terminal extends in a direction inclined with respect to the horizontal direction including the central axis of the base material, it becomes easier for wind to reach the case portion that houses the electrode terminal, thereby cooling the electrode terminal.

[0008] The electrode case may further include a cylindrical electrode case that houses a portion of the pair of electrode terminals therein, the electrode case being disposed on the outside of an outer tube that houses the base material and extending in a direction perpendicular to the central axis of the base material while being integrated with the outer tube.

[0009] With this configuration, the electrode case is more easily exposed to air, allowing the electrode terminals to be cooled.

[0010] According to this configuration, the pair of electrode terminals may extend along a vertical direction.

[0011] With this configuration, the insulator that covers the outside of the electrically heated catalytic converter can be sandwiched from both above and below in the vertical direction, which makes it easier to assemble the insulator. Effect of the Invention

[0012] In the present invention, since the electrode terminal is disposed vertically above the central axis of the base material, it is possible to prevent condensed water generated during cold conditions from coming into contact with the electrode terminal. This makes it possible to prevent the formation of a leakage path due to condensed water. In addition, since the electrode terminal extends in a direction inclined with respect to the horizontal direction including the central axis of the base material, wind can easily reach the case portion that houses the electrode terminal, thereby cooling the electrode terminal. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram showing a schematic diagram of an electrically heated catalyst device according to an embodiment; [Diagram 2] FIG. 11 is a diagram for explaining an electrically heated catalyst device according to a modified example. [Diagram 3] 10 is a diagram for explaining a case where a leakage path is formed due to condensed water in an electrically heated catalyst device of a comparative example. FIG. [Figure 4] FIG. 2 is a perspective view showing an electrically heated catalyst device of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an electrically heated catalytic converter according to an embodiment of the present invention will be described in detail. Note that the present invention is not limited to the embodiment described below.

[0015] 1 is a diagram showing a schematic diagram of an electrically heated catalyst device in an embodiment. The electrically heated catalyst device 1 is mounted on a vehicle equipped with an internal combustion engine and is provided in an exhaust passage of the internal combustion engine. The electrically heated catalyst device 1 includes a substrate 2 that supports a catalyst, a pair of electrodes 3, a retaining mat 4, a pair of electrode terminals 5, lead wires 6, and a case 10. The substrate 2, the pair of electrodes 3, the retaining mat 4, the pair of electrode terminals 5, and the lead wires 6 are housed inside the case 10.

[0016] The substrate 2 is a carrier with a honeycomb structure, and has a plurality of passages formed along the exhaust gas flow direction. A catalyst is supported on the surface of each passage of the substrate 2. For example, a three-way catalyst is supported on the substrate 2. The substrate 2 is also electrically conductive. The substrate 2 is made of a material that generates heat when electricity is passed through it. The substrate 2 is made of silicon carbide, for example. The substrate 2 is formed in a cylindrical shape. The central axis CL of the substrate 2 extends along the exhaust gas flow direction.

[0017] The pair of electrodes 3 are components for applying a voltage to the substrate 2. The pair of electrodes 3 are attached to the outer circumferential surface of the substrate 2. The pair of electrodes 3 are conductors made of metal. The pair of electrodes 3 extend in the circumferential direction of the substrate 2 and also in the axial direction of the substrate 2. The pair of electrodes 3 are also disposed at positions corresponding to the openings of the retaining mat 4.

[0018] The retaining mat 4 is a mat that retains the substrate 2 in the case 10. The retaining mat 4 is wrapped around the outer peripheral surface of the substrate 2 and is interposed between the outer tube 11 of the case 10 and the substrate 2. The retaining mat 4 is a component for retaining the substrate 2 at a predetermined position within the outer tube 11, and is made of an electrically insulating material. The pair of electrodes 3 are electrically connected to the substrate 2 while being electrically insulated from the outer tube 11. The openings of the retaining mat 4 are provided at positions corresponding to the pair of electrodes 3.

[0019] The case 10 has an outer cylinder 11, a first electrode cover 12, and a second electrode cover 13. The outer cylinder 11, the first electrode cover 12, and the second electrode cover 13 are all made of metal. The outer cylinder 11 is a case portion that houses the base material 2. The outer cylinder 11 extends along the axial direction of the base material 2. The outer cylinder 11 is provided with an opening 11a at a position corresponding to the pair of electrodes 3. The first electrode cover 12 and the second electrode cover 13 are integrated with the outer cylinder 11 so as to cover the opening 11a of the outer cylinder 11.

[0020] The first electrode cover 12 and the second electrode cover 13 form an electrode chamber 14 that houses a pair of electrodes 3. The electrode chamber 14 is an internal space defined by the substrate 2, the retaining mat 4, the outer cylinder 11, the first electrode cover 12, and the second electrode cover 13. Inside the electrode chamber 14, the electrode 3 is electrically connected to the electrode terminal 5. In the electrode chamber 14, the electrode terminal 5 is electrically connected to the electrode 3 via a lead wire 6.

[0021] The pair of electrode terminals 5 are rod-shaped electrodes and function as external electrodes relative to the electrode 3. The electrode terminals 5 are electrically connected to an external power source with a portion of the electrode terminals 5 housed inside the first electrode cover 12 and the second electrode cover 13. For example, the pair of electrode terminals 5 are electrically connected to the power source via a cable provided outside the case 10. By applying a voltage to the substrate 2 via the pair of electrode terminals 5 and the pair of electrodes 3, the substrate 2 generates heat, and the catalyst supported on the substrate 2 is heated.

[0022] Moreover, the pair of electrode terminals 5 extend in the same direction as the central axis CL of the base material 2. The longitudinal direction of the pair of electrode terminals 5 is the same as the extension direction of the central axis CL of the base material 2. When the central axis CL of the base material 2 extends along the horizontal direction, the pair of electrode terminals 5 extend in the horizontal direction.

[0023] Furthermore, the pair of electrode terminals 5 are disposed vertically above the central axis CL of the base material 2. When the central axis CL of the base material 2 extends horizontally, the pair of electrode terminals 5 are disposed vertically above a horizontal plane including the central axis CL of the base material 2.

[0024] In the electrically heated catalyst device 1 configured in this manner, the opening 11a of the outer cylinder 11 is closed by the first electrode cover 12 and the second electrode cover 13 in order to prevent exhaust gas from leaking from the case 10 to the outside of the exhaust passage. Since the inside of the case 10 is a gas atmosphere, condensed water may be generated when it is cold, and the condensed water may accumulate inside the electrode chamber 14. In this case, if the condensed water comes into contact with the electrode terminal 5 or the conductive part of the electrode terminal 5, the electrode terminal 5 and the case 10 may be electrically connected through the condensed water, or the conductive part of the electrode terminal 5 and the case 10 may be electrically connected through the condensed water, and there is a concern that a leakage path may be formed. In order to prevent this, in the electrically heated catalyst device 1, the pair of electrode terminals 5 are arranged vertically above the central axis CL of the substrate 2. With this arrangement, even if the condensed water generated when it is cold accumulates inside the electrode chamber 14, the condensed water can be prevented from coming into contact with the electrode terminal 5.

[0025] As described above, by disposing the electrode terminal 5 vertically above the central axis CL of the base material 2, it is possible to prevent the electrode terminal 5 from coming into contact with the condensed water in the electrode chamber 14. This makes it possible to prevent the electrode terminal 5 and the case 10 from being electrically connected to each other via the condensed water, and to prevent the formation of a leakage path.

[0026] It is also possible to configure a modified version of the electrically heated catalyst device 1. In the modified electrically heated catalyst device 1, the pair of electrode terminals 5 are configured to extend in a direction perpendicular to the central axis CL of the substrate 2. In other words, the direction in which the pair of electrode terminals 5 extend is not limited to the same direction as the central axis CL of the substrate 2. In other words, the direction in which the pair of electrode terminals 5 extend does not have to be the horizontal direction.

[0027] FIG. 2 is a diagram for explaining an electrically heated catalytic device in a modified example. In the electrically heated catalytic device 1 in the modified example, a pair of electrode terminals 5 extend along the vertical direction. Since the pair of electrode terminals 5 are rod-shaped electrodes, the central axis L1 of the electrode terminals 5 is in the same direction as the vertical direction. The pair of electrode terminals 5 extend vertically upward from the portion connected to the lead wire 6. When the central axis CL of the substrate 2 extends horizontally, the central axis L1 of the electrode terminals 5 extends in a direction perpendicular to the horizontal plane including the central axis CL of the substrate 2. The pair of electrode terminals 5 are partially housed in a cylindrical electrode case 15. The electrode case 15 is integrated with the first electrode cover 12 and the second electrode cover 13. The electrode case 15 is disposed outside the outer tube 11, and extends in a direction perpendicular to the central axis CL of the substrate 2 when integrated with the outer tube 11.

[0028] The electrode terminal 5 is held in the electrode case 15 via an insulating member. The insulating member that holds the electrode terminal 5 serves as a partition wall, separating the inside of the electrode chamber 14 from the inside of the electrode case 15. The electrode terminal 5 is disposed so as to penetrate the insulating member provided at the boundary between the inside of the electrode chamber 14 and the inside of the electrode case 15. One end of the electrode terminal 5 is accommodated in the electrode case 15, and the other end of the electrode terminal 5 is accommodated in the electrode chamber 14. A part of the electrode terminal 5 on the power supply side is accommodated in the electrode case 15, and a part of the electrode terminal 5 on the substrate 2 side is accommodated in the electrode chamber 14. According to this modification, in the electrode chamber 14, the lower end of the electrode terminal 5 is disposed vertically above the lower end of the opening 11a, so that the condensed water in the electrode chamber 14 can be prevented from coming into contact with the electrode terminal 5. Furthermore, since the electrode case 15 extends in a direction perpendicular to the central axis CL of the substrate 2, it becomes easy to assemble an insulator to the electrically heated catalytic device 1. It becomes possible to assemble the insulators so as to sandwich the electrically heated catalytic device 1 from above and below in the vertical direction.

[0029] Also in this modified example, the pair of electrode terminals 5 can be disposed vertically above the central axis CL of the substrate 2. That is, the electrically heated catalytic device 1 can be disposed so that the pair of electrode terminals 5 are disposed vertically above the central axis CL of the substrate 2 and extend in a direction perpendicular to the horizontal plane SA including the central axis CL of the substrate 2. Inside the electrode chamber 14, the lower end of the electrode terminal 5 is disposed vertically above the lower end of the opening 11a. Inside the electrode chamber 14, the bottom of the electrode chamber 14 is formed by the first electrode cover 12 attached to the opening 11a. When condensed water is generated inside the electrode chamber 14 during cold operation, the condensed water accumulated at the bottom of the electrode chamber 14 by the first electrode cover 12 flows from the electrode chamber 14 into the inside of the outer tube 11 when it exceeds the lower end of the opening 11a. This can prevent the condensed water from coming into contact with the electrode terminal 5. Therefore, it is possible to prevent the formation of a leakage path through the condensed water.

[0030] For comparison, a comparative example is shown in FIG. 3. As shown in FIG. 3, in the electrically heated catalytic device 100 of the comparative example, the electrode terminal 101 is disposed vertically below the central axis CL of the substrate 102. The electrode 103 attached to the outer peripheral surface of the substrate 102 is electrically connected to the electrode terminal 101 via the lead wire 104. The electrode chamber 105 accommodates the joint between the electrode terminal 101 and the lead wire 104. Inside the electrode chamber 105, the bottom of the electrode chamber 105 is formed by the electrode cover 106. When condensed water is generated inside the electrode chamber 105 during cold operation, the electrode chamber 105 is positioned vertically below the opening of the outer cylinder 107, so that the condensed water comes into contact with a part of the electrode terminal 101 (the part located inside the electrode chamber 105). Therefore, a leakage path is formed through the condensed water.

[0031] In addition, in the modified example, the pair of electrode terminals 5 are not limited to a configuration in which they are arranged to extend in a direction perpendicular to the central axis CL of the substrate 2, but may be arranged to be inclined at a predetermined angle with respect to the central axis CL of the substrate 2. In other words, the inclination angle of the central axis L1 of the electrode terminal 5 with respect to the central axis CL of the substrate 2 can be set to any angle of 90 degrees or less. For example, when the central axis CL of the substrate 2 extends in a horizontal direction, the pair of electrode terminals 5 extend in a direction inclined with respect to a horizontal plane SA including the central axis CL of the substrate 2. According to this modified example, the distance between the outer tube 11 and the electrode terminal 5 is increased, so that the heat input from the outer tube 11 to the electrode terminal body and the cable can be suppressed. Since the electrode case 15 is arranged to be inclined at an angle with respect to the outer tube 11, it is expected that the electrode terminal 5 will be actively exposed to the running wind and cooled. Furthermore, compared to the comparative example shown in FIG. 4, the distance between the electrode terminal body and the EGR pipe is increased, so that the longitudinal constraint of the electrode terminal 5 is relaxed. 4, in the electrically heated catalytic device 100 of the comparative example, the electrode terminal body 110 extends along the outer tube 107, so the distance between the outer tube 107 and the electrode terminal body 110 is short, resulting in large heat input to the electrode terminal body 110 and the cable. In addition, the EGR pipe 120 exists in the longitudinal direction of the electrode terminal body 110, which places restrictions on the electrode terminal 101 in the longitudinal direction.

[0032] The pair of electrode terminals 5 need only be configured to be inclined with respect to the central axis CL of the base material 2, and the respective inclination angles do not necessarily have to be the same. In other words, the pair of electrode terminals 5 need only be configured such that their lower ends are positioned vertically above the central axis CL and extend in a direction inclined with respect to the central axis CL, and they do not need to be configured symmetrically with respect to a vertical plane including the central axis CL. [Explanation of symbols]

[0033] 1 Electrically heated catalytic converter 2 Base material 3 electrodes 4 Retaining mat 5 electrode terminal 6 Lead Wire 10 Cases 11 Outer cylinder 12 First electrode cover 13 Second electrode cover 14 Electrode chamber

Claims

1. A substrate that generates heat when electricity is applied thereto; A pair of electrode terminals electrically connected to the substrate; The electrically heated catalyst device includes: a pair of electrode terminals that apply a voltage to the substrate, whereby a catalyst supported on the substrate is heated via the substrate; The pair of electrode terminals are rod-shaped electrodes, are disposed vertically above a central axis of the base material, and extend in a direction inclined with respect to a horizontal plane including the central axis of the base material. An electrically heated catalytic converter.

2. a cylindrical electrode case that accommodates a portion of the pair of electrode terminals therein; The electrode case is disposed outside an outer cylinder that houses the base material, and extends in a direction perpendicular to a central axis of the base material while being integrated with the outer cylinder.

2. The electrically heated catalytic converter according to claim 1,

3. The pair of electrode terminals extend vertically.

3. The electrically heated catalytic converter according to claim 2.

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