JP2013158714A - Electrically heated catalyst device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrically heated catalyst device allowing reduction of a mounting space.SOLUTION: An electrically heated catalyst device 1 includes: a honeycomb body 2 having a cell formation part 21 and a cylindrical sheath part 22 covering the periphery thereof; a pair of electrodes 31, 32 oppositely disposed in the radial direction on the peripheral face 221 of the sheath part 22; and a pair of electrode terminals 310, 320 respectively projecting from these electrodes (31, 32) outward in the radial direction of the honeycomb body 2. When assuming an optional reference line 19 which is parallel to the axial direction and is present on the sheath part 22, side end border lines 315, 325 in the electrodes 31, 32 are inclined with a prescribed inclination to the reference line 19 in the full length. The pair of electrode terminals 310, 320 is formed at a prescribed interval in the axial direction, and an angle made by the pair of electrode terminals 310, 320 when observing the electrically heated catalyst device 1 from one end face 28, 29 in the axial direction is less than 180°.

Description

  The present invention relates to an electrically heated catalyst device (EHC) for purifying exhaust gas from automobiles and the like.

A catalyst device for purifying exhaust gas is provided in an exhaust pipe of a vehicle such as an automobile. As this catalyst device, for example, a honeycomb body on which a catalyst such as Pt, Pd, or Rh is supported is used.
By the way, for activation of the catalyst, for example, heating at about 400 ° C. is required. Therefore, an electrically heated catalyst device (EHC) has been developed in which a pair of electrodes is formed on the surface of a honeycomb body or the like, and the honeycomb body or the like is heated by energizing the pair of electrodes.

  The electrically heated catalyst device is, for example, a honeycomb body having a cell forming portion and a cylindrical outer skin portion that covers the periphery of the cell forming portion, and an outer circumferential surface of the outer skin portion of the honeycomb body, which is disposed to face each other in the radial direction. A pair of electrodes and a pair of electrode terminals respectively protruding from the pair of electrodes outward in the radial direction of the honeycomb body. The electric heating type catalyst device having such a configuration is arranged in a state of being accommodated in a case, for example, in an exhaust gas pipe under a floor of a vehicle. And in an electrically heated catalyst apparatus, it supplies with electricity to a pair of electrode via the electrode terminal from the power supply provided outside, and a honeycomb body is heated.

  The pair of electrodes provided on the outer skin of the honeycomb body are provided so as to face each other, and the pair of electrode terminals formed on each electrode are also provided so as to face each other at an angle of 180 °. Since the electrode terminal is provided so as to protrude outward in the radial direction of the honeycomb body, the electric heating catalyst device includes a large dimension in the radial direction when the electrode terminal is included. Therefore, for example, in order to accommodate in the limited narrow space under the floor of a vehicle, it has been desired to make the radial dimension smaller.

  Further, when at least one of the pair of electrode terminals protruding outward in the radial direction of the honeycomb body is disposed below the vehicle body (on the ground side), for example, under the floor of the vehicle, water adheres to the electrode terminals due to condensed water or water immersion. It becomes easy to do. As a result, a short circuit may occur between the electrode terminal and the case containing the electrically heated catalyst device. Therefore, it is necessary to arrange the pair of terminals in the horizontal direction (direction parallel to the ground) and install the electrically heated catalyst device in the exhaust gas pipe. In this case, however, the horizontal mounting space becomes large. There was a problem.

  For example, Patent Document 1 proposes a technique related to an electrode structure that can be applied to an electrically heated catalyst device or the like. In this technique, an electrode structure is proposed in which an electrode body (electrode terminal) and a lead wire are arranged at a predetermined angle, and the whole is bent. By using such an electrode structure, it is possible to save space.

JP-A-9-82457

  However, in the above-described bent electrode structure, it is necessary to electrically connect the electrode body and the electrode provided on the surface of the honeycomb body with a metal connecting member. Therefore, in the electrically heated catalyst device exposed to high temperature, the heat resistance of the metallic connecting member becomes a problem, and it is difficult to maintain electrical conduction. Therefore, it is practically difficult to employ the above-described electrode structure using a connecting member for an electrically heated catalyst device. Accordingly, there has been a demand for the development of a highly feasible electric heating catalyst device that can reduce the mounting space.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide an electrically heated catalyst device capable of reducing the mounting space.

One aspect of the present invention is a honeycomb body having a cell forming portion and a cylindrical outer skin portion that surrounds the cell forming portion, and a pair of radially disposed opposing outer peripheral surfaces of the outer skin portion of the honeycomb body. An electrically heated catalyst device comprising an electrode and a pair of electrode terminals projecting outward in the radial direction of the honeycomb body from the pair of electrodes,
Assuming an arbitrary reference line that is parallel to the axial direction of the honeycomb body and is on the outer skin part, a side end contour line extending in the axial direction of the honeycomb body in the electrode has a total length that is predetermined with respect to the reference line. Is inclined at
The distance between the pair of electrodes in the circumferential direction of the honeycomb body is constant,
The pair of electrode terminals are formed at the center in the circumferential direction of the honeycomb body of the pair of electrodes at a predetermined interval in the axial direction of the honeycomb body, and the electric heating catalyst device is connected to the honeycomb body. An angle formed by the pair of electrode terminals when observed from one end face in the axial direction of the body is less than 180 ° (claim 1).

  In the electric heating catalyst device, as described above, the pair of electrode terminals are formed at an angle of less than 180 °. Therefore, the radial dimension of the honeycomb body in the electric heating type catalyst device can be reduced. Therefore, for example, when the electric heating catalyst device is disposed in an exhaust gas pipe such as under the floor of a vehicle, the mounting space can be reduced. Moreover, when the said electrically heated catalyst apparatus is installed in an exhaust gas pipe, it becomes possible to install both said pair of electrode terminals toward the upper direction rather than a horizontal direction. Therefore, it is possible to more reliably avoid the problem of short circuit due to the condensed water or water immersion.

  In the electrically heated catalyst device, a distance between the pair of electrodes in the circumferential direction of the honeycomb body is constant, and a side edge contour line extending in the axial direction of the honeycomb body in the electrode has a total length of the reference line. With a predetermined inclination. Therefore, as described above, when the pair of electrode terminals are respectively formed in the center of the pair of electrodes in the circumferential direction of the honeycomb body and arranged at a predetermined interval in the axial direction of the honeycomb body, as described above. The angle formed by the pair of electrode terminals can be made less than 180 °.

  In the electric heating catalyst device, the honeycomb body is configured so as to cover the cell forming portion with a cylindrical outer skin portion, and has a circular cross section perpendicular to the axial direction. Therefore, in the pair of electrodes provided along the outer peripheral surface of the outer skin portion of the honeycomb body, the distance between the electrodes in the facing direction of the pair of electrodes varies depending on the location. Specifically, the distance between the electrodes decreases as the distance from the circumferential center of each electrode increases. For this reason, the current flows more easily between the electrodes as it goes outward from the center in the circumferential direction of each electrode. Therefore, between the pair of electrodes, the interval between the side end contour lines of the electrodes extending in the substantially axial direction of the honeycomb body is shortened, and electric power is easily concentrated on the side end contour lines.

In the electric heating catalyst device, assuming the reference line, the side edge contour line extending in the substantially axial direction of the honeycomb body in the electrode is not parallel to the reference line in its entire length, and the reference line It is arranged in the direction that intersects. That is, the side end contour line is formed so as not to be parallel to the axial direction of the honeycomb body.
Therefore, even if electric power is concentrated on the side end contour line, the side end contour line is not parallel to the axial direction of the honeycomb body, so that thermal stress is concentrated along a specific axial direction of the honeycomb body. Can be prevented. That is, thermal stress can be dispersed and relaxed across a plurality of cells. Therefore, breakage of the honeycomb body can be prevented.

Further, the pair of electrode terminals are respectively formed at the center in the circumferential direction of the honeycomb body in the pair of electrodes. Therefore, when a voltage is applied between the electrode terminals, the honeycomb body can be heated uniformly without unevenness.
In the electric heating catalyst device, the distance between the pair of electrodes in the circumferential direction of the honeycomb body is constant. That is, the distance along the circumferential direction between the side edge contour lines is constant, and the pair of electrodes are arranged to face each other without being biased in the circumferential direction of the outer peripheral surface of the honeycomb body. Therefore, in the electric heating catalyst device, a region sandwiched between the pair of electrodes is increased. Therefore, the honeycomb body can be uniformly heated by energizing the electrodes. Moreover, the space | interval of the said side edge outline in a pair of electrodes can be made equal. Therefore, the distance between the one side end contour lines is not shortened compared to the other, and power is concentrated between the one side end contour lines when the electrodes are energized, and the honeycomb body is damaged due to thermal stress. Can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. Explanatory drawing which shows a mode that the electrically heated catalyst apparatus in Example 1 was observed from the one end surface of the axial direction. Explanatory drawing which shows a mode that the electrically heated catalyst apparatus in Example 1 was observed from the other end surface of the axial direction. Explanatory drawing which shows the expanded view of the external shape of the electrically heated catalyst apparatus in Example 1. FIG. Explanatory drawing which shows the cross-section of the state which accommodated the electrically heated catalyst apparatus in Example 1 in the case. BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows a mode that the electrically heated catalyst apparatus mounted in the mounting space of a vehicle in Example 1 was observed from one end surface of the axial direction. FIG. Explanatory drawing which shows a mode that the electrically heated catalyst apparatus in Example 2 was observed from one end surface of the axial direction. Explanatory drawing which shows a mode that the electrically heated catalyst apparatus in Example 2 was observed from the other end surface of the axial direction. Explanatory drawing which shows the expanded view of the external shape of the electrically heated catalyst apparatus in Example 2. FIG. Explanatory drawing which shows a mode that the electrically heated catalyst apparatus which formed the insulating layer in Example 3 in the same thickness as an electrode was observed from one end surface of an axial direction. Explanatory drawing which shows a mode that the electrically heated catalyst apparatus which formed the insulating layer with the same thickness as an electrode in Example 3 was observed from the other end surface of the axial direction. Explanatory drawing which shows the cross-section in the state which accommodated in the case the electrically heated catalyst apparatus which formed the insulating layer in Example 3 in the same thickness as an electrode. Explanatory drawing which shows a mode that the electrically heated catalyst apparatus which formed the insulating layer so that an outer skin part and an electrode might be covered completely in Example 3 was observed from one end surface of the axial direction. Explanatory drawing which shows a mode that the electrically heated catalyst apparatus which formed the insulating layer with respect to the electrode which formed the level | step difference in both ends in Example 3 was observed from the one end surface of the axial direction. In Example 3, it is explanatory drawing which shows a mode that the electric heating type catalyst apparatus which formed the insulating layer with respect to the electrode which formed the taper part in both ends was observed from the one end surface of the axial direction. Explanatory drawing which shows the whole structure of the electrically heated catalyst mounting in the comparative example 1. Explanatory drawing which shows a mode that the electric heating type catalyst apparatus which has arrange | positioned the electrode terminal in the perpendicular direction in the comparative example 1 was observed from the one end surface of the axial direction. Explanatory drawing which shows a mode that the electric heating type catalyst apparatus which has arrange | positioned the electrode terminal in the horizontal direction in the comparative example 1 was observed from one end surface of the axial direction.

Next, a preferred embodiment of the electric heating catalyst device will be described.
The electric heating catalyst device includes a honeycomb body having a cell forming portion and a cylindrical outer skin portion that covers the periphery of the cell forming portion, and a pair of radially disposed opposing outer peripheral surfaces of the outer skin portion of the honeycomb body. And a pair of electrode terminals projecting outward from each of the pair of electrodes in the radial direction of the honeycomb body.
The cell forming portion of the honeycomb body can be constituted by, for example, porous partition walls arranged in a lattice shape and a plurality of cells extending in the axial direction surrounded by the partition walls.

The honeycomb body is preferably made of porous ceramics mainly composed of SiC.
In this case, it becomes easy to impart conductivity to the honeycomb body, and the surface area can be increased.

The conductivity of the honeycomb body can be adjusted by, for example, the composition of the material. Specifically, when SiC is used as the material of the honeycomb body, N, B, Al, etc. as impurities are dissolved in the SiC, and the electric resistivity is adjusted by controlling the amount of impurities. Thus, the conductivity can be controlled. When Si—SiC is used as the material of the honeycomb body, conductivity can be controlled by impregnating SiC with metal silicon (Si) and adjusting the amount of Si.
Further, a catalyst exhibiting exhaust gas purification performance can be supported on the partition walls of the cell forming portion of the honeycomb body. As the catalyst, a three-way catalyst composed of Pt, Pd, Rh or the like can be used.

Next, in the electrically heated catalyst device, the distance between the pair of electrodes in the circumferential direction of the honeycomb body is constant. Further, assuming an arbitrary reference line that is parallel to the axial direction of the honeycomb body and is on the outer skin portion, a side end outline extending in the substantially axial direction of the honeycomb body in the electrode is parallel to the reference line. Instead, the side edge contour line is inclined with a predetermined inclination with respect to the reference line.
When the side edge contour line is parallel to the reference line, the pair of electrode terminals are formed horizontally when the pair of electrode terminals are formed in the center of the pair of electrodes in the circumferential direction of the honeycomb body. . Therefore, the dimension in the radial direction of the electric heating type catalyst device is increased, and the mounting space in the exhaust gas pipe is increased.
Further, when the side end contour line is parallel to the reference line, the side end contour line of the electrode is parallel to the axial direction of the cells of the honeycomb body. Therefore, when a current is applied between the pair of electrodes and power is concentrated on the side end contour line, thermal stress is concentrated along a specific axial direction of the honeycomb body. As a result, thermal stress concentrates on specific cells extending in the axial direction of the electrically heated catalyst device, and the honeycomb body may be damaged.

In the electric heating catalyst device, the distance between the pair of electrodes in the circumferential direction of the honeycomb body is constant.
When the interval between the pair of electrodes in the circumferential direction is not constant and one electrode is formed to be biased toward the other electrode in the circumferential direction, the side with the smaller interval when energized between the electrodes The distance between the side end contours of the electrode becomes small, and power is concentrated on the side end contour. As a result, thermal stress is concentrated and the honeycomb body may be damaged. In addition, when the distance between the pair of electrodes in the circumferential direction is not constant, there is a possibility that current flows easily in the circumferential direction of the honeycomb body on the side where the distance is small when the pair of electrodes is energized. As a result, in this case, there is a possibility that the inside of the honeycomb body cannot be sufficiently heated even when energized.

Next, an interval in the axial direction between the pair of electrodes on the outer peripheral surface of the honeycomb body is preferably larger than an interval in the circumferential direction between the pair of electrodes on the outer peripheral surface of the honeycomb body ( Claim 6).
In the outer peripheral surface, when the distance between the electrodes in the axial direction is smaller than the distance in the circumferential direction, when the current is applied between a pair of electrodes, the axial direction is applied to the outer peripheral surface of the outer skin portion. There is a risk that current will flow easily. As a result, even if energization is performed, it may be difficult to sufficiently heat the inside of the honeycomb body.

In addition, the shortest distance between the pair of electrodes in the radial direction of the honeycomb body can be smaller than the shortest distance between the pair of electrodes on the outer peripheral surface of the honeycomb body.
In this case, it is possible to prevent a current from flowing on the outer peripheral surface of the outer skin portion when energization is performed between the pair of electrodes of the electric heating catalyst device. The shortest distance between the pair of electrodes in the radial direction of the honeycomb body is the distance in the radial direction between the side edge contour lines that are close to each other in the circumferential direction between the pair of electrodes.

  The distance in the axial direction between the pair of electrodes on the outer peripheral surface, the distance in the circumferential direction between the pair of electrodes on the outer peripheral surface, the shortest distance between the pair of electrodes in the radial direction of the honeycomb body, and the The shortest distance between the pair of electrodes on the outer peripheral surface of the honeycomb body is, for example, the circumferential width of the electrode, the axial length of the electrode, the diameter of the honeycomb body, and the axial direction of the honeycomb body. It can be controlled by adjusting the length, the inclination of the side edge contour line, and the like.

Moreover, it is preferable that the said side edge outline is inclined at 45 degrees or less with respect to the said reference line (Claim 4).
In this case, the distance between the pair of electrodes on the outer peripheral surface of the honeycomb body can be increased. Therefore, it is possible to prevent a current from flowing on the outer peripheral surface when energization is performed between the pair of electrodes. Therefore, the inside of the honeycomb body can be sufficiently heated by energization.

Further, in the electric heating catalyst device, the side end contour line is inclined at a predetermined inclination with respect to the reference line, and the side end contour line is substantially parallel between the pair of electrodes. It is formed.
Moreover, a pair of said electrode can each be distribute | arranged substantially helically on the said outer peripheral surface of the said outer skin part. As used herein, the term “spiral” includes a case where each electrode does not spirally travel around the outer peripheral surface, and includes a case where the number of rounds is less than one round, for example, half or 2/3.

  Moreover, it is preferable that the said electrode is formed with the uniform width | variety in the said circumferential direction of the said honeycomb body over the full length. In this case, the electrodes can be easily formed, and the pair of the electrodes are arranged to face each other, whereby the distance between the pair of the electrodes in the circumferential direction of the honeycomb body can be easily made constant. it can.

The acute angle formed by the side edge contour line and the reference line is θ, the width in the circumferential direction of the electrode is D, the length of the side edge contour line is E, and the circumferential direction of the honeycomb body It is preferable that the relationship of D + E × sin θ ≧ R / 2 is satisfied, where R is the length of the outer periphery at (Claim 5).
In this case, for example, when the pair of the electrodes is energized in the honeycomb body supporting a catalyst such as a three-way catalyst, the cell forming portion on the exhaust gas stream line when the exhaust gas passes through the honeycomb body. At any position in the axial direction, a portion where the catalyst is activated by energization heat generation can be configured in a short time, and the exhaust gas purification performance can be improved.
In the case of D + E × sin θ <R / 2, when the honeycomb body is heated by energizing a pair of the electrodes, it is caused by energization heat generation at any position in the axial direction of the cell forming portion of the honeycomb body. There is a possibility that a portion where the catalytic activity cannot be generated occurs, and the exhaust gas may pass through the inactive catalyst portion.

Moreover, as a material which comprises the said electrode, conductive ceramics, such as Si-SiC which impregnated Si (metallic silicon) to SiC and SiC, Cr, Fe, Ni, Mo, Mn, Si, Ti, Nb, for example A metal such as Al or an alloy thereof can be used. A conductive ceramic is preferable.
Further, as the conductive ceramic, in addition to the above-described Si—SiC, it is possible to use a conductive ceramic obtained by impregnating SiC with one or more metals selected from Si, Cr, Fe, Ni, Al, and the like. it can.

  In forming the electrode on the outer peripheral surface of the honeycomb body, for example, a method of baking an electrode material as a raw material of the electrode and then sticking it with an adhesive, or applying a paste-like electrode material to the outer peripheral surface of the honeycomb body A method of firing and firing can be employed. These methods can be used in combination.

A method of attaching the above electrode material to the honeycomb body after firing will be described in the examples described later.
In the method of applying and baking the paste-like electrode material, specifically, first, at least one metal selected from Si, Cr, Fe, Ni, Al, and the like and SiC are contained. A binder, a surfactant, a pore former, water and the like are added to the electrode raw material, and mixed and kneaded to produce a paste-like electrode material. Next, for example, a rubber plate having a desired thickness is cut out in the shape of an electrode, this rubber plate is disposed on the outer peripheral surface of the outer skin portion of the honeycomb body, and the cut-out portion of the rubber plate is filled with a paste-like electrode material. Then, in order to make the thickness of the electrode material constant, the cut-out portion is removed with a squeegee to remove excess electrode material. Next, the rubber plate is removed from the outer peripheral surface of the honeycomb body in a state where the electrode material formed in the hollowed portion is left on the outer peripheral surface of the honeycomb body, and then fired at a constant temperature. Thereby, a pair of electrodes can be provided on the outer peripheral surface of the outer skin portion of the honeycomb body.

In addition, it is preferable that an insulating layer made of an electrically insulating material covering the outer skin portion is formed at least on a portion of the outer skin portion of the honeycomb body where the electrode is not formed.
In this case, in the electric heating catalyst device, the insulation in the circumferential direction of the honeycomb body can be enhanced.

  The insulating layer can be formed with the same thickness as the electrode formed on the outer skin portion of the honeycomb body. In this case, the step between the outer peripheral surface of the honeycomb body and the electrode can be eliminated. Therefore, when the electric heating catalyst device is accommodated in a case and an elastic holding mat is used between the outer peripheral surface of the electric heating catalyst device and the case, the electric heating type catalyst device is used by the holding mat. The surface pressure applied to the outer peripheral surface of the catalyst device can be made uniform. Therefore, the stress reduction effect by the holding mat can be improved.

  The insulating layer can be formed not only on at least a portion of the outer skin portion of the honeycomb body where the electrode is not formed, but also on the electrode. Also in this case, the step on the outer peripheral surface of the honeycomb body can be eliminated. The insulating layer can be formed of a single layer of an electrically insulating material, but can also be formed of a laminate of two or more layers. In the case of forming with two or more layers, the same electrical insulating material can be used, but each layer can also be formed with different electrical insulating materials.

The insulating layer is preferably formed of a material having electrical insulating properties and mechanical low physical properties similar to those of the electrode.
In this case, the thermal stress applied to the electrode and the honeycomb body can be reduced.
The insulating layer can be formed of an insulating material such as alumina or silicon oxide, for example.

  The electrically heated catalyst device includes a pair of electrode terminals that protrude from the pair of electrodes outward in the radial direction of the honeycomb body. The electrode terminal can be formed so as to extend perpendicular to the tangent to the outer circumference of the cylindrical honeycomb body. The electrode terminal can be formed of a columnar member made of conductive ceramics or conductive metal. A conductive ceramic is preferable.

The electrode terminal is formed at the center of the electrode in the circumferential direction of the honeycomb body. If the electrode terminals are formed so as to be shifted from the center, the honeycomb body may not be heated evenly and uniformly when energized.
Further, the pair of electrode terminals is formed such that an angle formed by the pair of electrode terminals when the electric heating catalyst device is observed from one end face in the axial direction of the honeycomb body is less than 180 °. . When the angle formed by the pair of electrode terminals is 180 °, that is, when the pair of electrode terminals are formed horizontally, the dimension of the electric heating catalyst device in the radial direction becomes large. This increases the space for mounting on the vehicle.

  In addition, the pair of electrode terminals are formed on the pair of electrodes at intervals in the axial direction of the honeycomb body. Since the pair of electrodes is formed with a predetermined inclination with respect to the axial direction as described above, the axial distance between the pair of electrodes can be adjusted to adjust the distance from one end surface of the honeycomb body in the axial direction. The angle formed by the pair of electrode terminals when observed can be adjusted.

  If the angle formed by the pair of electrode terminals is made smaller, the mounting space on the vehicle can be made smaller. The angle formed by the pair of electrode terminals is preferably 150 ° or less (Claim 3), more preferably 120 ° or less, and still more preferably 90 ° or less.

Example 1
Next, an example of an electrically heated catalyst device (EHC) will be described with reference to the drawings.
As shown in FIGS. 1 to 4, the electrically heated catalyst device 1 of this example includes a honeycomb body 2 having a cell forming portion 21 and a cylindrical outer skin portion 22 covering the periphery thereof, and an outer skin portion 22 of the honeycomb body 2. A pair of electrodes 31, 32 that are opposed to each other in the radial direction on the outer peripheral surface 221, and a pair of electrode terminals 310, 320 that protrude from the electrodes 31, 32 outward in the radial direction of the honeycomb body 2, respectively.

As shown in FIGS. 1 and 4, in the electrically heated catalyst device 1, assuming an arbitrary reference line 19 parallel to the axial direction X of the honeycomb body 2 and on the outer skin portion 22, the honeycomb body 2 in the electrodes 31 and 32. The side edge contour lines 315 and 325 extending substantially in the axial direction X are not parallel to the reference line 19 and the entire length thereof is inclined with respect to the reference line 19 at a predetermined inclination θ1.
Moreover, as shown in FIG. 4, in the electrically heated catalyst device 1, the distances A1 and B1 between the pair of electrodes 31 and 32 in the circumferential direction of the honeycomb body 2 are constant. In FIG. 4, the sum of the interval B1a and the interval B1b is the interval B1.

The pair of electrode terminals 310 and 320 are formed at the center of the pair of electrodes 31 and 32 in the circumferential direction of the honeycomb body 2 at a predetermined interval in the axial direction X of the honeycomb body 2.
When the electrically heated catalyst device 1 is observed from one end face 28, 29 in the axial direction of the honeycomb body 2, as shown in FIGS. 2 and 3, the angle α1 formed by the pair of electrode terminals 310, 320 is 180 °. Is less than. FIG. 2 is a view of the electrically heated catalyst device 1 observed from one end face 28 in the axial direction of the honeycomb body 2, and one electrode terminal 310 of the pair of electrode terminals 310 and 320 is in front of the paper surface. The other electrode terminal 320 is located on the back side of the drawing. On the other hand, FIG. 3 is a diagram in which the electrically heated catalyst device 1 is observed from the other end face 29 in the axial direction of the honeycomb body 2, and one electrode terminal 310 of the pair of electrode terminals 310 and 320 is deep in the drawing. The other electrode terminal 320 is located on the front side of the drawing.
2 to 4, the pair of electrodes 31 and 32 formed on the outer peripheral surface 221 of the honeycomb body 2 do not show the cross section, but in order to make the positional relationship between the electrodes 31 and 32 easy to understand. The electrodes 31 and 32 are shown hatched. The same applies to FIGS. 7 to 11, 13 to 15, 17, and 18 described later.
Hereinafter, the electrically heated catalyst device of this example will be described in more detail.

As shown in FIGS. 1 to 3, in the electrically heated catalyst device 1, the honeycomb body 2 includes a cell forming portion 21 and a cylindrical outer skin portion 22 that covers the periphery of the cell forming portion 21, and has a diameter of 93 mm as a whole. The cylindrical shape is 100 mm in length in the axial direction. The honeycomb body 2 is made of porous ceramics mainly composed of SiC.
The cell forming part 21 is composed of porous partition walls 211 arranged in a quadrangular lattice shape and a large number of cells 212 surrounded by the partition walls 211 and extending in the axial direction.

  As shown in FIGS. 1 to 3, a pair of electrodes 31 and 32 made of conductive ceramics mainly composed of a Si—SiC composite material are formed on the outer peripheral surface 221 of the outer skin portion 22 of the honeycomb body 2. . The electrodes 31 and 32 are disposed to face each other in the radial direction Y of the honeycomb body 2. The electrodes 31 and 32 have a constant width D1 (width D1 in the circumferential direction of the honeycomb body 2) on the outer peripheral surface 221, and from one end portion 28 to the other end portion 29 in the axial direction X of the honeycomb body 2. (See FIG. 4).

  As shown in FIGS. 1 and 4, assuming an arbitrary reference line 19 that is parallel to the axial direction of the honeycomb body 2 and is on the outer skin portion 22, the side ends of the electrodes 31 and 32 that extend in the substantially axial direction X of the honeycomb body 2. The contour lines 315 and 325 are not parallel to the reference line 19 in their entire length, but are arranged in a direction intersecting the reference line 19. In this example, since the electrodes 31 and 32 are formed from one end portion 28 (29) to the other end portion 29 (28) in the axial direction X of the honeycomb body 2 as described above, the honeycomb body 2 If the length in the axial direction is C1, and the lengths of the side edge contour lines 315 and 325 are E1, E1> C1. In this example, E1 = 138 mm and C1 = 100 mm. The side end outlines 315 and 325 are inclined at a predetermined inclination θ1 (θ1 = 42 °) with respect to the reference line 19, and the pair of electrodes 31 and 32 are formed on the outer skin portion 22 of the honeycomb body 2. The outer peripheral surface 221 is arranged in a substantially spiral shape.

  As shown in FIG. 4, in the electrically heated catalyst device 1 of this example, the angle (acute angle) formed between the side edge contour lines 315 and 325 and the reference line 19 is θ1, and the width in the circumferential direction of the electrodes 31 and 32 is D1. Assuming that the length of the side edge contour lines 315 and 325 is E1, and the length of the outer periphery in the circumferential direction of the honeycomb body 2 is R1, the relationship of D1 + E1 × sin θ1 ≧ R1 / 2 is satisfied. In this example, D1 = 60 mm, E1 = 138 mm, θ1 = 42 °, and R1 = 292 mm.

  As shown in FIG. 4, in the electrically heated catalyst device 1 of the present example, the pair of electrodes 31 and 32 have portions where the same reference line 19 intersects on the outer peripheral surface 221 of the outer skin portion 22. More specifically, in the electrically heated catalyst device 1 of the present example, the pair of electrodes 31 and 32 intersect with the same reference line 19 at both ends in the axial direction X of the honeycomb body 2. The distance F1 in the axial direction X between the pair of electrodes 31 and 32 on the outer peripheral surface 221 of the honeycomb body 2 is larger than the distance A1 and B1 in the circumferential direction between the pair of electrodes 31 and 32 on the outer peripheral surface 221. It is configured. In this example, F1 = 100 mm, A1 = 88 mm, B1a = 62 mm, B1b = 26 mm, and B1 = B1a + B1b = 88 mm.

As shown in FIGS. 1 to 3, the pair of electrodes 31 and 32 are provided with electrode terminals 310 and 320 for energization. The electrode terminals 310 and 320 are made of conductive ceramics whose main component is a Si—SiC composite material, and the shape thereof is cylindrical. The electrode terminals 310 and 320 are formed so as to protrude outward in the radial direction of the honeycomb body 2 from the electrodes 31 and 32, respectively.
As shown in FIG. 4, the electrode terminals 310 and 320 are formed at the centers of the electrodes 31 and 32 in the circumferential direction of the honeycomb body 2, respectively. That is, when the width in the circumferential direction of the electrodes 31 and 32 is D1, the electrode terminals 310 and 320 are formed at positions D1 / 2 in the circumferential direction from the side edge contour lines 315 and 325 of the electrodes 31 and 32.

As shown in FIGS. 1 and 4, the pair of electrode terminals 310 and 320 are formed on the electrodes 31 and 32, respectively, with a predetermined interval in the axial direction X of the honeycomb body 2. In this example, the electrode terminal 310 is formed in the vicinity of one end face 28 in the axial direction X of the honeycomb body 2, and the electrode terminal 320 is formed in the vicinity of the other end face 29.
In this example, as shown in FIGS. 2 and 3, the electrically heated catalyst device 1 was observed from one end face 28, 29 in the axial direction of the honeycomb body 2 (direction perpendicular to the paper surface in FIGS. 2 and 3). As described above, the pair of electrode terminals 310 and 320 are formed at intervals in the axial direction X so that the angle α1 formed by the pair of electrode terminals 310 and 320 is 80 °.

In the electrically heated catalyst device 1, an energization means (not shown) having an external power source is connected to the electrode terminals 310 and 320 of the electrodes 31 and 32 (see FIG. 1). Further, a catalyst is supported on the surface of the partition wall 211 of the cell forming portion 21 in the honeycomb body 2. In this example, a three-way catalyst such as Pt, Pd, and Rh, which are noble metals, was used as the catalyst.
In the electrically heated catalyst device 1, the honeycomb body 2 can be heated by energizing the pair of electrodes 31 and 32 by energizing means (not shown).

Next, the manufacturing method of the electrically heated catalyst device 1 of this example will be briefly described (see FIGS. 1 to 3).
First, a honeycomb body 2 made of porous ceramics mainly composed of SiC was manufactured, and a three-way catalyst was supported on the honeycomb body 2. The honeycomb body 2 carrying the catalyst can be produced by a known production method.
Next, a pair of electrodes 31 and 32 was formed on the outer peripheral surface 221 of the outer skin portion 22 of the honeycomb body 2.
Specifically, first, sheet-like electrode materials to be the electrodes 31 and 32 were each formed into a desired shape. Next, the compact was fired to obtain electrodes 31 and 32 made of a fired body mainly composed of a Si—SiC composite material.
Next, electrodes 31 and 32 were disposed on the outer peripheral surface 221 of the outer skin portion 22 of the honeycomb body 2 via a paste-like adhesive containing a Si—SiC composite material, carbon, binder, and the like (see FIG. 1). . Then, the honeycomb body 2 in which the electrodes 31 and 32 are arranged on the outer peripheral surface 221 of the outer skin portion 22 was heated and fired at a predetermined temperature (about 1600 ° C.) and a predetermined atmospheric condition (Ar atmosphere, normal pressure). As a result, the pair of electrodes 31 and 32 were joined to the outer peripheral surface 221 of the outer skin portion 22 of the honeycomb body 2.

Next, electrode terminal materials containing conductive ceramics were formed into a cylindrical shape and fired to obtain electrode terminals 310 and 320. The electrode terminals 310 and 320 are made of a fired body (conductive ceramic) mainly composed of a Si—SiC composite material. Next, the electrode terminals 310 and 320 were joined to the electrodes 31 and 32 formed on the outer skin portion 22 of the honeycomb body 2 through a paste-like adhesive containing a Si—SiC composite material, carbon, binder, and the like.
In this way, as shown in FIG. 1, the honeycomb body 2, the pair of electrodes 31 and 32 disposed radially opposite to each other on the outer peripheral surface 221, and the radial direction of the honeycomb body 2 from these electrodes 31 and 32, respectively. An electrically heated catalyst device 1 having a pair of electrode terminals 310 and 320 projecting outward was prepared.

As shown in FIG. 5, the electrically heated catalyst device 1 is used by being housed in, for example, a metal case 10. A fibrous holding mat 12 is arranged between the case 10 and the electrically heated catalyst device. The electrode terminal 310 made of conductive ceramics of the electrically heated catalyst device 1 is electrically connected to the lead wire 312 via the metal electrode terminal 311. Although not shown in the figure, the other electrode terminal 320 is also electrically connected to the other lead wire 322 via the metal electrode terminal.
The electrode terminal 310 and the metal electrode terminal 311 are joined to each other. For joining, for example, brazing or the like is used. Further, the metal electrode terminal 311 is provided with a stress relaxation structure (not shown), and can absorb the positional deviation between the case 10 and the honeycomb body 2 and the case 10 and the electrode terminal 310 due to vibration or the like. In addition, the metal electrode terminal 311 and the lead wire 312 are connected by caulking or the like so as to maintain electrical continuity.

  FIG. 6 shows an example of mounting the electrically heated catalyst device 1 in the space under the floor of the vehicle. As shown in the figure, the space for mounting the electrically heated catalyst device 1 is limited because of the frame and the body under the floor of the vehicle. In the figure, the dimensions between the heat shield plate 199 that is a metal partition wall constituting the vehicle frame and the electrically heated catalyst device 1 are M = 150 mm, N = 115 mm, and β = 20 °. In addition, the diameter of the honeycomb body in the electrically heated catalyst device 1 is 93 mm as described above.

Next, the effect of the electrically heated catalyst device 1 of this example will be described.
As shown in FIGS. 1 to 3, in the electrically heated catalyst device 1 of this example, as described above, the angle α <b> 1 formed by the pair of electrode terminals 310 and 320 is 80 °, and the pair of electrode terminals 310 is formed. , 320 is less than 180 °. Therefore, the dimension in the radial direction Y of the honeycomb body 2 in the electrically heated catalyst device 1 can be reduced. Therefore, for example, when the electrically heated catalyst device 1 is disposed in an exhaust gas pipe such as under the floor of a vehicle, the mounting space can be reduced. Moreover, when the electrically heated catalyst device 1 is installed in the exhaust gas pipe, it is possible to install both the pair of electrode terminals 310 and 320 upward from the horizontal direction (see FIGS. 5 and 6). ). Therefore, it is possible to more reliably avoid the problem of short circuit due to the condensed water or water immersion.

  As shown in FIG. 4, in the electrically heated catalyst device 1, the distances A <b> 1 and B <b> 1 between the pair of electrodes 31 and 32 in the circumferential direction of the honeycomb body 2 are constant, and in the axial direction X of the honeycomb body in the electrodes 31 and 32. The extending side end contour lines 315 and 325 are inclined with respect to the reference line 19 at a predetermined inclination θ1 (θ1 = 42 °). Therefore, as in this example, a pair of electrode terminals 310 and 320 are formed at the center of the pair of electrodes 31 and 32 in the circumferential direction of the honeycomb body 2, and a predetermined interval is provided in the axial direction X of the honeycomb body 2. As described above, the angle formed by the pair of electrode terminals 310 and 320 can be made less than 180 °. In this example, the example of θ1 = 42 ° is shown, but θ1 can be changed as appropriate.

  As shown in FIGS. 2 and 3, in the electrically heated catalyst device 1, the honeycomb body 2 is configured to cover the cell forming portion 21 with a cylindrical outer skin portion 22, and is orthogonal to the axial direction. The cross section is circular. Therefore, the pair of electrodes 31 and 32 provided along the outer peripheral surface 221 of the outer skin portion 22 of the honeycomb body 2 has different distances between the electrodes 31 and 32 in the facing direction of the electrodes 31 and 32 depending on the location. Specifically, the distance between the electrodes 31 and 32 decreases as the distance from the circumferential center of the electrodes 31 and 32 increases. For this reason, the current is more likely to flow between the electrodes 31 and 32 as it goes outward from the center in the circumferential direction of the electrodes 31 and 32. Therefore, between the pair of electrodes 31, 32, the distance between the side end contour lines 315, 325 of the electrodes 31, 32 extending in the substantially axial direction of the honeycomb body 2 is shortened, and power is supplied to the side end contour lines 315, 325. It becomes easy to concentrate.

As shown in FIGS. 1 and 4, in the electrically heated catalyst device 1 of the present example, assuming the reference line 19, side end contour lines 315 and 325 extending in the substantially axial direction X of the honeycomb body 2 in the electrodes 31 and 32. Are not arranged parallel to the reference line 19 but are arranged in a direction intersecting the reference line 19. That is, the side edge contour lines 315 and 325 are formed so as not to be parallel to the axial direction X of the honeycomb body 2.
Therefore, even if electric power is concentrated on the side end contour lines 315 and 325, the side end contour lines 315 and 325 are not parallel to the axial direction X of the honeycomb body 2, so that thermal stress is generated in a specific axial direction X of the honeycomb body 2. Concentration along the line can be prevented. That is, the thermal stress is not concentrated on one cell 212 extending in the axial direction X, and the thermal stress can be dispersed and relaxed over the plurality of cells 212. Therefore, damage to the honeycomb body 2 can be prevented.

Moreover, as shown in FIGS. 1-4, a pair of electrode terminal 310,320 is formed in the center of the circumferential direction of the honeycomb body 2 in a pair of electrodes 31,32, respectively. Therefore, when a voltage is applied between the electrode terminals 310 and 320, the honeycomb body 2 can be heated uniformly without deviation.
In the electrically heated catalyst device 1, the distances A1 and B1 between the pair of electrodes 31 and 32 in the circumferential direction of the honeycomb body 2 are constant. That is, the distances A1 and B1 along the circumferential direction between the side edge contour lines 315 and 325 are equal and constant in the extending direction of the electrodes 31 and 32, and one electrode 31 (32) is the outer circumferential surface 221 of the honeycomb body 2. Are arranged to face each other without being biased toward the other electrode 32 (31) side. Therefore, the region sandwiched between the pair of electrodes 31 and 32 in the honeycomb body 2 becomes large, and the honeycomb body 2 can be heated uniformly by energizing the electrodes 31 and 32. In this case, the intervals A1 and B1 between the side edge contour lines 315 and 325 of the pair of electrodes 31 and 32 can be made equal (in FIG. 4, the interval A1 = the interval B1 = the interval B1a + the interval B2b). Therefore, the distance between the one side end contour lines 315 and 325 is not shortened compared to the other, and power is concentrated between the one side end contour lines 315 and 325 when the electrodes 31 and 32 are energized. The honeycomb body 2 can be prevented from being damaged by thermal stress.

Further, in the electrically heated catalyst device 1, the honeycomb body 2 has a cylindrical outer skin portion 22 and has a substantially columnar shape as a whole.
Therefore, handling of the electrically heated catalyst device 1 becomes very easy. For example, the operation of accommodating the electrically heated catalyst device 1 in the exhaust pipe of the vehicle is facilitated. In addition, the electrically heated catalyst device 1 can be accommodated while being held from the outer periphery with a uniform force, and the occurrence of cracks or the like of the electrically heated catalyst device 1 due to vibration, stress, or the like can be suppressed. Thereby, the mountability of the electrically heated catalyst device 1 can be sufficiently secured.

  The honeycomb body 2 is made of porous ceramics mainly composed of SiC. Therefore, it becomes easy to give the honeycomb body 2 conductivity, and the surface area can be increased.

As shown in FIG. 4, in the electrically heated catalyst device 1, the pair of electrodes 31 and 32 intersect with the same reference line 19 on the outer peripheral surface 221 of the outer skin portion 22. The distance F1 in the axial direction X between the pair of electrodes 31 and 32 on the outer peripheral surface 221 of the honeycomb body 2 is larger than the distance A1 and B1 in the circumferential direction between the pair of electrodes 31 and 32 on the outer peripheral surface of the honeycomb body 2. It is getting bigger.
When the gap F1 between the electrodes 31 and 32 in the axial direction X is smaller than the gaps A1 and B1 in the circumferential direction on the outer circumferential surface 221, when energization is performed between the pair of electrodes 31 and 32, the outer skin portion There is a concern that current may easily flow in the axial direction X on the outer peripheral surface 221 of 22. As a result, it may be difficult to sufficiently heat the inside of the honeycomb body 2 even when energization is performed.

  Further, in the electrically heated catalyst device 1 of this example, as shown in FIG. 4, the angle (acute angle) formed between the side edge contour lines 315 and 325 and the reference line 19 is θ1, and the electrodes 31 and 32 are arranged in the circumferential direction. When the width is D1, the lengths of the side edge contour lines 315 and 325 are E1, and the outer peripheral length in the circumferential direction of the honeycomb body 2 is R1, the relationship of D1 + E1 × sin θ1 ≧ R1 / 2 is satisfied. Therefore, as shown in FIGS. 1 to 3, for example, when the pair of electrodes 31 and 32 are energized in the honeycomb body 2 supporting a catalyst such as a three-way catalyst, the exhaust gas flow when the exhaust gas passes through the honeycomb body 2 A portion where the catalyst is activated by energization heat generation can be formed in a short time at any position in the axial direction of the cell forming portion 21 on the line, and the exhaust gas purification performance can be improved.

  Further, as shown in FIG. 1, in the electrically heated catalyst device 1 of the present example, current is supplied between a pair of electrodes 31 and 32 via a pair of electrode terminals 310 and 320 by a current supply means (not shown). The honeycomb body 2 can be heated uniformly. Thereby, the catalyst supported by the honeycomb body 2 can be activated as a whole efficiently, and the exhaust gas purification performance can be exhibited at an early stage.

(Example 2)
This example is an example of an electrically heated catalyst device in which the angle formed by a pair of electrode terminals is different from that of the first embodiment.
As shown in FIGS. 7 to 9, the electrically heated catalyst device 4 of the present example is similar to the first embodiment in that a honeycomb body 40 having a cell forming portion 41 and a cylindrical outer skin portion 42 covering the periphery thereof, and a honeycomb A pair of electrodes 45, 46 disposed radially opposite to each other on the outer peripheral surface 421 of the outer skin portion 42 of the body 40, and a pair of electrodes projecting outward from each of these electrodes 45, 46 in the radial direction Y of the honeycomb body 40 Terminals 450 and 460 are provided.

  As shown in FIG. 9, in this example, one electrode terminal 450 of the pair of electrode terminals 450 and 460 is on the electrode 45 formed on the outer peripheral surface 421 of the honeycomb body 40 as in the first embodiment. Thus, the honeycomb body 40 is formed in the vicinity of one end face 408 in the axial direction X. On the other hand, the other electrode terminal 460 is formed on the electrode 46 formed on the outer peripheral surface 421 of the honeycomb body 40 and in the center in the axial direction X of the honeycomb body 40. The other configuration is the same as that of the first embodiment, and the electrodes 31 and 32 have side end contour lines 455 and 465 that are not parallel to the reference line 49 over the entire length, and have a predetermined inclination θ1 with respect to the reference line 19. It is inclined at (θ1 = 42 °). Therefore, as shown in FIG. 7 and FIG. 8, when the electrically heated catalyst device 4 of this example is observed from one end face 408, 409 in the axial direction of the honeycomb body 40, the angle α2 formed by the electrode terminals 450, 460 is It becomes larger than the angle α1 of Example 1, and α2 = 150 °.

As in this example, by relatively changing the formation position of the pair of electrode terminals 450 and 460 in the axial direction of the honeycomb body, the angle formed by the pair of electrode terminals 450 and 460 can be adjusted to a desired angle. . In addition, the angle formed by the pair of electrode terminals can be adjusted to a desired angle by changing the diameter of the honeycomb body, the length in the axial direction, and the inclination of the electrode formed on the outer peripheral surface with respect to the reference line. You can also.
The electrically heated catalyst device 4 of this example has the same configuration as that of Example 1 except that the angles formed by the electrode terminals 450 and 460 are different, and can exhibit the same effects as those of Example 1. it can.

(Example 3)
This example is an example of an electrically heated catalyst device in which an insulating layer is formed on at least a portion of the outer skin portion of the honeycomb body where no electrode is formed.
As shown in FIGS. 10 and 11, the electrically heated catalyst device 5 of the present example is similar to the first embodiment, in which a honeycomb body 50 having a cell forming portion 51 and a cylindrical outer skin portion 52 covering the periphery thereof, A pair of electrodes 55, 56 disposed radially opposite to each other on the outer peripheral surface 421 of the outer skin portion 52 of the body 50, and a pair of electrodes projecting outward from each of the electrodes 55, 56 in the radial direction Y of the honeycomb body 50. Terminals 550 and 560 are provided. As in Example 1, a pair of electrodes when the electrically heated catalyst device 5 is observed from one end face 508, 509 in the axial direction of the honeycomb body 50 (direction perpendicular to the paper surface in FIGS. 10 and 11). The pair of electrode terminals 550 and 560 are formed so that an angle α1 formed by the terminals 550 and 560 is 80 °.

In the electrically heated catalyst device 5 of this example, an insulating layer 53 made of an electrically insulating material is formed in a portion of the outer skin portion 52 of the honeycomb body 50 where the electrodes 55 and 56 are not formed. The insulating layer 53 is formed with the same thickness as the electrodes 55 and 56 in a portion where the electrodes 55 and 56 are not formed. In this example, the insulating layer 53 is made of SiO ₂ . An insulating material such as Al ₂ O ₃ can be used instead of SiO ₂ . The insulating layer 53 can be formed by applying an insulating material and performing heat treatment. The insulating layer 53 made of an insulating material can also be formed by a chemical reaction.
The electrically heated catalyst device 5 of this example has the same configuration as that of Example 1 except that the insulating layer 53 is provided.

  In the electrically heated catalyst device 5 of this example, an insulating layer 53 made of an electrically insulating material is formed in a portion of the outer skin portion 52 of the honeycomb body 50 where the electrodes 55 and 56 are not formed. Therefore, the insulation in the circumferential direction of the honeycomb body 50 can be enhanced. In addition, as shown in FIG. 12, the electrically heated catalyst device 5 is used by housing it in a case 10 and placing an elastic holding mat 12 between the electrically heated catalyst device 5 and the case 10. At this time, if the insulating layer 53 is formed on the outer skin portion 52 of the honeycomb body 50 as described above, for example, the metal case 10 and the honeycomb body 50, and the side edge contour portions 551 of the case 10 and the electrodes 55 and 56 are used. , 561 can be improved in insulation.

  The insulating layer 53 is formed with the same thickness as the electrodes 55 and 56 formed on the outer skin portion 52 of the honeycomb body 50. Therefore, the step between the outer peripheral surface 521 of the honeycomb body 50 and the electrodes 55 and 56 can be eliminated. Therefore, as shown in FIG. 12, when the electrically heated catalyst device 5 is accommodated in the case 10 and the elastic holding mat 12 is used between the electrically heated catalyst device 5 and the case 10, it is retained. The surface pressure applied to the outer periphery of the electrically heated catalyst device 5 by the mat 12 can be made uniform. Therefore, the stress reduction effect by the holding mat 12 can be improved, and the honeycomb body 50 can be prevented from being damaged during assembling (canning) to the case, and the honeycomb body 50 and the electrodes 55 and 56 can be prevented from being cracked by the impact of exhaust gas. Can do.

In this example, the insulating layer 53 is made of SiO ₂ and is made of a material having mechanical properties close to those of the electrodes 55 and 56. Therefore, thermal stress can be reduced. Mechanical properties include Young's modulus and linear expansion coefficient. That is, the Young's modulus of the electrodes 55 and 56 and the Young's modulus of the insulating layer 53 are preferably the same or close. Moreover, it is desirable that the linear expansion coefficient of the honeycomb body 50, the linear expansion coefficient of the electrodes 55 and 56, and the linear expansion coefficient of the insulating layer 53 are the same or close.
Further, the electrically heated catalyst device 5 of this example has the same configuration as that of Example 1 except that the insulating layer 53 is provided, and exhibits the same effects as those of Example 1 described above. be able to.

  In the above-described example, the example in which the insulating layer 53 is formed with the same thickness as the electrodes 55 and 56 in the portion of the outer skin portion 52 of the honeycomb body 50 where the electrodes 55 and 56 are not formed is shown. As shown, the insulating layer 53 can be formed so as to completely cover the electrodes 55 and 56 as well as the portion where the electrodes 55 and 56 are not formed in the outer skin portion 52. As a result, the insulating layer 53 becomes the outermost layer, and also in this case, the step between the outer peripheral surface 521 of the honeycomb body 50 and the electrodes 55 and 56 can be eliminated. As a result, cracking of the honeycomb body 50 and the electrodes 55 and 56 during canning can be prevented, and assemblability can be ensured. Furthermore, the insulation can be improved, and leakage or short circuit between the outer periphery of the electrodes 55 and 56 and the case 10 can be sufficiently prevented.

In the above example, the electrodes 55 and 56 are formed such that the side ends 551 and 561 of the pair of electrodes 55 and 56 in the circumferential direction of the honeycomb body 50 are perpendicular to the outer peripheral surface 521 of the honeycomb body 50. An example in which the insulating layer 53 is formed is shown (see FIGS. 10, 11, and 13). On the other hand, the electrodes 55 and 56 are inclined with respect to the axial direction, and as shown in FIG. 14, steps 553 and 563 are formed at both ends in the circumferential direction of the electrodes 55 and 56, respectively, or as shown in FIG. In some cases, tapered portions 554 and 564 that gradually decrease in thickness toward the outer side in the circumferential direction are formed at both ends in the circumferential direction of the pair of electrodes 55 and 55.
In this case, it is further effective against the problem that electric power tends to concentrate on the side edge contour line of the electrode, which is one of the problems of the conventional electric heating type catalyst device.

  In other words, the interval between the electrodes 55 and 56 becomes shorter as the distance from the center portion in the circumferential direction of the electrodes 55 and 56 increases. For this reason, the current flows more easily between the electrodes 55 and 56 from the center in the circumferential direction of the electrodes 55 and 56 to the outside. Therefore, between the pair of electrodes 55, 56, the distance between the side end contours 551, 561 of the electrodes 55, 56 extending substantially in the axial direction of the honeycomb body 50 is shortened, and power is concentrated on the side end contours. There is a problem that it becomes easy to do. On the other hand, as described above, steps 553 and 563 are formed at both ends of the electrodes 55 and 56 in the circumferential direction (see FIG. 14), or tapered portions 554 and 564 are formed (see FIG. 15). The thickness of the electrodes 55 and 56 can be reduced and the electrical resistance can be increased from the central part in the circumferential direction of the honeycomb body 50 to the outside. Therefore, current concentration in the side edge contour lines of the electrodes 55 and 56 can be suppressed. As a result, the stress applied to the honeycomb body 50 can be further reduced by a synergistic effect with the above-described technique in which the electrodes 55 and 56 are inclined with respect to the axial direction. The technique of inclining the electrodes 55 and 56 with respect to the axial direction and the technique of forming the steps 553 and 563 or the tapered portions 554 and 564 at both ends in the circumferential direction of the electrodes 55 and 56 are used in combination. This is particularly effective when the low-strength honeycomb substrate 50 is used.

As described above, even when the steps 553 and 563 are formed at both ends in the circumferential direction of the electrodes 55 and 56 or the tapered portions 554 and 564 are formed, respectively, as shown in FIGS. By forming the layer 53, the step between the outer peripheral surface 521 of the honeycomb body 50 and the electrodes 55 and 56 can be eliminated. The insulating layer 53 increases the insulation in the circumferential direction of the honeycomb body 50, and the insulation between the case 10 made of metal or the like and the honeycomb body 50 when the electrically heated catalyst device 5 is housed in the case 10. In addition, the insulation between the case 10 and the side edge contour lines 551 and 561 of the electrodes 55 and 56 can be enhanced. Furthermore, breakage of the honeycomb body 50 during assembly (canning) to the case 10 and cracking of the honeycomb body 50 and the electrodes 55 and 56 due to the impact of exhaust gas can be prevented.
It should be noted that the steps 553 and 563 and the tapered portions 554 and 564 are formed at both ends in the circumferential direction of the electrodes 55 and 56, respectively (see FIGS. 14 and 15), but they are not clearly illustrated. However, as shown in FIG. 13, the insulating layer 53 can be formed so as to completely cover not only the portion where the electrodes 55 and 56 are not formed in the outer skin portion 52 but also the electrodes 55 and 56. As a result, the assembling property can be ensured, the insulating property can be further improved, and the leakage and short circuit between the outer periphery of the electrodes 55 and 56 and the case 10 can be sufficiently prevented.

(Comparative Example 1)
Next, a comparative example for the electrically heated catalyst device of the above-described embodiment will be described.
As shown in FIGS. 16 to 18, the electrically heated catalyst device 9 of the present example is similar to the first embodiment in that a honeycomb body 90 having a cell forming portion 91 and a cylindrical outer skin portion 92 covering the periphery thereof, and a honeycomb A pair of electrodes 93, 94 disposed opposite to each other in the radial direction Y on the outer peripheral surface 921 of the outer skin portion 92 of the body 90, and a pair of protrusions projecting outward from each of the electrodes 93, 94 in the radial direction Y of the honeycomb body 90. And electrode terminals 930 and 940.

  In the electrically heated catalyst device 9 of the present example, the electrodes 93 and 94 extending in the axial direction X of the honeycomb body 90 are formed with a uniform width in the circumferential direction of the honeycomb body, and the side edge contour lines 935 and 945 are formed. Are formed to be parallel to the axial direction X. The pair of electrode terminals 930 and 940 are formed at the center in the circumferential direction of the honeycomb body 2 of the pair of electrodes 93 and 94, respectively, and are also formed at the center in the axial direction X. Therefore, the pair of electrode terminals 930 and 940 are arranged so as to be aligned horizontally (180 °).

For this reason, in the electrically heated catalyst device 9 of this example, when the electrode terminals 930 and 940 are included, the dimension in the radial direction Y becomes large. Therefore, the space at the time of mounting becomes large and, for example, it is not suitable for accommodating in a limited narrow space under the floor of the vehicle.
Further, as shown in FIG. 17, for example, a vehicle in which at least one of the pair of electrode terminals 930 and 940 projecting outward in the radial direction Y of the honeycomb body 90 is directed downward (ground side) of the vehicle body. If it is arranged under the floor of the water, the water tends to adhere to the electrode terminal 940 due to the condensed water or water immersion. As a result, for example, there is a possibility that a short circuit may occur between the electrode terminal 940 and a case (not shown) that houses the electrically heated catalyst device 9. In addition, as shown in FIG. 18, the pair of electrode terminals 930 and 940 can be arranged in the horizontal direction (direction parallel to the ground) to install the electrically heated catalyst device 9 in the exhaust gas pipe. , The horizontal mounting space will increase.

DESCRIPTION OF SYMBOLS 1 Electric heating type catalyst apparatus 2 Honeycomb body 21 Cell formation part 22 Outer skin part 221 Outer peripheral surface 31 Electrode 32 Electrode 310 Electrode terminal 320 Electrode terminal

Claims (7)

A honeycomb body (2, 40, 50) having a cell forming part (21, 41, 51) and a cylindrical outer skin part (22, 42, 52) covering the periphery of the cell forming part (21, 41, 51); , A pair of electrodes (31, 32, 45,...) Disposed radially opposite to the outer peripheral surface (221, 421, 521) of the outer skin portion (22, 42, 52) of the honeycomb body (2, 40, 50). 46, 55, 56) and a pair of electrode terminals projecting outward in the radial direction of the honeycomb body (2, 40, 50) from the pair of electrodes (31, 32, 45, 46, 55, 56), respectively. (310, 320, 450, 460, 550, 560), an electrically heated catalyst device (1, 4, 5),
Assuming an arbitrary reference line (19, 49) parallel to the axial direction of the honeycomb body (2, 40, 50) and on the (22, 42, 52), the electrode (31, 32, 45, 46) , 55, 56), the side end contour lines (315, 325, 455, 465) extending in the axial direction of the honeycomb body (2, 40, 50) have an overall length with respect to the reference line (19, 49). It is inclined at a predetermined inclination,
The distance between the pair of electrodes (31, 32, 45, 46, 55, 56) in the circumferential direction of the honeycomb body (2, 40, 50) is constant,
The pair of electrode terminals (310, 320, 450, 460, 550, 560) are spaced apart from each other by a predetermined distance in the axial direction of the honeycomb body (2, 40, 50), respectively. 45, 46, 55, 56) is formed at the center in the circumferential direction of the honeycomb body (2, 40, 50), and the electrically heated catalyst device (1, 4, 5) is connected to the honeycomb body (2). , 40, 50) formed by the pair of electrode terminals (310, 320, 450, 460, 550, 560) when observed from one end face (28, 29, 408, 409, 508, 509) in the axial direction. An electrically heated catalyst device (1, 4, 5) characterized in that the angle is less than 180 °.   The electrically heated catalyst device (1, 4, 5) according to claim 1, wherein at least the electrode (31, 32, 52) in the outer skin portion (22, 42, 52) of the honeycomb body (2, 40, 50). 45, 46, 55, 56) is formed with an insulating layer (53) made of an electrically insulating material covering the outer skin portion (22, 42, 52). Electrically heated catalyst device (1, 4, 5).   In the electrically heated catalyst device (1, 4, 5) according to claim 1 or 2, an angle formed by the pair of electrode terminals (310, 320, 450, 460, 550, 560) is 150 ° or less. An electrically heated catalyst device (1, 4, 5).   The electrically heated catalyst device (1, 4, 5) according to any one of claims 1 to 3, wherein the side edge contour lines (315, 325, 455, 465) are arranged on the reference line (19, 49). Electrically heated catalyst device (1, 4, 5), which is inclined at 45 ° or less with respect to the above.   In the electrically heated catalyst device (1, 4, 5) according to any one of claims 1 to 4, the side end contour lines (315, 325, 455, 465)) and the reference line (19, 49). ) Is θ, the width of the electrodes (31, 32, 45, 46, 55, 56) in the circumferential direction is D, and the side edge contours (315, 325, 455, 465) And the length of the outer periphery in the circumferential direction of the honeycomb (2, 40, 50) body is R, and satisfies the relationship D + E × sin θ ≧ R / 2. Catalytic device (1, 4, 5).   The electrically heated catalyst device (1, 4, 5) according to any one of claims 1 to 5, wherein a pair of the honeycomb bodies (2, 40, 50) on the outer peripheral surface (221, 421, 521). The distance between the electrodes (31, 32, 45, 46, 55, 56) in the axial direction is a pair of the above-described outer peripheral surfaces (221, 421, 521) of the honeycomb body (2, 40, 50). An electrically heated catalyst device (1, 4, 5) characterized by being larger than the interval in the circumferential direction between the electrodes (31, 32, 45, 46, 55, 56).   The electrically heated catalyst device (1, 4, 5) according to any one of claims 1 to 6, wherein the honeycomb body (2, 40, 50) is made of a porous ceramic mainly composed of SiC. An electrically heated catalyst device (1, 4, 5).

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