JP3312934B2 - Electric heating type honeycomb body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an exhaust gas purifying apparatus which is used as an exhaust gas purifying means for an automobile by being interposed in an exhaust pipe system. More specifically, the present invention provides:
The present invention relates to an electrically heated honeycomb body incorporated in an exhaust gas purifying apparatus in order to improve a major drawback of this type of exhaust gas purifying apparatus, that is, a problem of a low exhaust gas purification rate at the time of engine start (cold start). .

[0002]

2. Description of the Related Art Conventionally, as a catalyst supporting base which is a main component of this type of exhaust gas purifying apparatus, there are a monolith type made of ceramics using a ceramic material such as cordierite, and a metal made of metal. Monolith type is known. Particularly recently, metal monolith type devices have been actively studied from the viewpoint of mechanical strength, durability, electric resistance, purification efficiency, miniaturization of devices, and the like. In the following description, the latter metal monolith type is mainly described for convenience of description. In general, a metal monolith type exhaust gas purifying apparatus stacks a flat strip made of a heat-resistant thin steel sheet and a corrugated strip formed by corrugating the thin steel sheet so as to have an abutting portion. Then, a honeycomb-shaped laminate (hereinafter, referred to as a honeycomb body) having a large number of mesh-shaped vent holes (hereinafter, referred to as cells) for an exhaust gas passage in the axial direction manufactured by winding and laminating the same in a spiral pattern. ) And a cylindrical metal case with both ends opened for loading and fixing the honeycomb body. The honeycomb body and the metal case are designed to withstand thermal expansion and thermal stress generated under a high temperature of the exhaust gas itself and a high temperature atmosphere due to an exothermic reaction between the exhaust gas and the purification catalyst. It is firmly fixed by brazing or welding so that it can withstand severe vibrations at the time. It goes without saying that the contact portions between the flat band material and the corrugated band material constituting the honeycomb body are fixed by various methods.

A major problem with this type of exhaust gas purifying apparatus is as follows. That is, at the time of starting the engine (at the time of cold start), the optimum temperature at which the exhaust gas purifying catalyst such as Pt, Pd, Rh supported on the wall surface of the metallic honeycomb body efficiently causes a catalytic reaction with the exhaust gas. The condition is not reached, and most of the harmful substances such as CO (carbon monoxide) and HC (hydrocarbon compounds) emitted from the engine are released to the atmosphere without being purified. . And this is about to be questioned from a pollution control perspective.

[0004] Various proposals have been made to solve the problems at the time of starting the engine (at the time of cold start). For example, (i) Japanese Utility Model Application Laid-Open No. 63-67609 discloses that a converter using a ceramic monolith type as a main catalyst supporting matrix is manufactured in advance in a honeycomb shape at a portion near the exhaust gas upstream side of the main catalyst supporting matrix. Coating a coated metal support with alumina and disposing an energizable metal monolith catalyst, (ii) 2-94
No. 316 discloses a method in which a far-infrared heater is provided on the outer peripheral portion of the catalyst body. (Iii) Japanese Utility Model Laid-Open No. 3-10022 discloses a heater on the front surface (upstream of exhaust gas) of a monolithic catalyst. A method of arranging a rectifying plate for rectifying exhaust gas in front of the heater. (Iv) Japanese Patent Application Laid-Open No. 2-277916 discloses that a desired number of corrugated strips are folded in a bellows shape to form one bundle. And a method in which an electrical insulator is disposed between adjacent layers of the bundle and electrical contacts are fixed to each end of the bundle. However, these conventional proposals are insufficient in the temperature rising temperature and the temperature of the temperature rising in view of the demand that the honeycomb body having the heater function be sufficiently heated to perform the catalytic reaction efficiently. The distribution is not satisfactory because the distribution is uneven, the cost is increased for the solution, and the strength of the honeycomb body itself is insufficient.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the conventional honeycomb body having a heater function. The present inventors have made various investigations on a technique for uniformly and sufficiently raising the temperature of the honeycomb body, particularly the entire inside of the honeycomb body at the time of cold start. In particular, the present inventors have enthusiastically studied the improvement of an electrically heated honeycomb body for an exhaust gas purifying device proposed in Japanese Utility Model Laid-Open No. 63-67609 described in the prior art.

As a result, the inventors of the present invention applied the heat-resistant thin metal sheet flat and corrugated strips proposed in Japanese Utility Model Application Laid-Open No. 63-67609 described as a prior art. It is stacked so that it is in contact with each other, and it is wound and formed to produce a wound type honeycomb body, and an electrode material is disposed at a central portion and an outer peripheral portion thereof to form a pre-heater (the above-mentioned prior art is a conventional type). Further, the wall surface of the honeycomb body is coated with alumina, but it is recognized that this is because the formed coating layer carries a catalyst for purifying exhaust gas.)
Found the following disadvantages. For example,
In the honeycomb body as an electric heating type preheater having the above-mentioned structure, the outer peripheral electrode material of the honeycomb body is a positive (positive) pole and the central electrode material is a negative (-) electrode with respect to an external power supply (battery or the like). (A) Outer peripheral electrode material (Because the honeycomb body is fixed in, for example, a conductive cylindrical metal case, the entire metal case becomes the outer peripheral electrode material.) Ratio of the current-carrying area formed by the flat band material and the corrugated band material per unit volume in the outer peripheral portion of the honeycomb body and the vicinity thereof with respect to the surface area of the honeycomb body (in other words, the ratio of the current density in this region is referred to as Can be.)
(B) The ratio of the current-carrying area formed by the flat band material and the corrugated band material per unit volume in the central part of the honeycomb body and the vicinity thereof to the surface area of the central electrode material (for example, Ni round bar material) ( Ratio of the current density at the site)
Since the former (a) is overwhelmingly more numerous, the current density flowing through the walls of the former cells is much smaller than the latter, in other words, the current at the outer peripheral portion of the honeycomb body and the vicinity thereof due to energization. The calorific value obtained by resistance heating is
The calorific value is small as compared with the calorific value obtained by resistance heating at the central portion of the honeycomb body and the vicinity thereof. As a result, the temperature inside the honeycomb body as the preheater becomes non-uniform.

Accordingly, an exhaust gas purifying apparatus incorporating a conventional electric heating type honeycomb body having a pre-heater function (the outline of the entire apparatus is the same as that shown in FIG. In FIG. 15), the inside is not uniformly heated and heated by energization, and the exhaust gas passing through the inside is unevenly heated and is supplied to the downstream main catalyst (MC: Main Converter). Reach. That is, the exhaust gas flows into the main catalyst (MC) without being uniformly heated to the optimum temperature for the catalytic reaction, and as a result, optimal exhaust gas purification cannot be achieved.
In addition, in the conventional electric heating type honeycomb body, when the central portion is set to an appropriate temperature due to the difference in current density described above, the outer peripheral portion becomes low in temperature. The area near the electrode material is overheated, and in extreme cases, meltdown (melt)
As a result, the vibration resistance (mechanical strength) of the honeycomb body is greatly impaired.

On the other hand, the present inventors, in the structure of the conventional honeycomb body having the pre-heater function, use the electrode material (the central electrode material B) as described in (a) and (b) above.
₁ , Conducting area (current density) for outer electrode material B ₂ )
It has been found that, when the means for making the same are substantially the same, the inside of the honeycomb body is uniformly heated, and thereby a high exhaust gas purification rate is achieved. An object of the present invention is to provide an exhaust gas purifying apparatus based on the above findings, and in particular, to provide an electric heating type honeycomb body having excellent heater characteristics, which is a main component thereof.

As is well known, an exhaust gas purifying apparatus incorporating an electrically heated honeycomb body is known in the art as an EHC.
(Electrically Heated Converter). This is the overall name including the main catalyst (MC).
On the other hand, the present invention particularly improves the structure of the electrically heated honeycomb body.
In connection with EHH (Electric
ally Heated Honeycomb). The honeycomb body itself may be abbreviated as H (Honeycomb).

[0010]

SUMMARY OF THE INVENTION In summary of the present invention,
According to the present invention, the casing and the central portion are formed as the outer peripheral electrode material and the central electrode material, respectively, and the flat band material and the corrugated band material made of a thin metal plate are brought into contact with each other around the central electrode material. A honeycomb body manufactured by stacking in the casing is fixed in the casing, each electrode is energized, and in the electric heating type honeycomb body having a structure capable of generating heat, a flat band material constituting the honeycomb body as the honeycomb body is provided. The brazing of the abutting portion with the corrugated strip is performed by brazing the abutting portion of the flat strip and the corrugated strip constituting the honeycomb body with the axial center of the honeycomb body. A cross section including at least one cross section including a plane or a surface extending from the electrode material to the outer peripheral portion of the honeycomb body, and having a larger ratio of a contact portion brazed from the outer peripheral portion of the honeycomb body toward the center electrode material. And further correct the honeycomb body A desired width (W) including the cross section is selected above, and the cross section is moved in parallel within the desired width (W) to form a space locus, and a brazed contact portion in the space locus is used. The present invention relates to an electrically heated honeycomb body. In other words, the present invention provides the electrically heated honeycomb body according to the present invention, wherein the honeycomb body comprises: A cross-section comprising: and a cross-section in which the ratio of the contact portion between the flat band material and the corrugated band material in the direction from the outer peripheral portion of the honeycomb body toward the central electrode material is defined in the honeycomb body, ii) at least two or more space regions (Z) having a desired width (W) including the cross section are defined in the honeycomb body; and (iii) a flat band member and a corrugated band member in the space region (Z). The present invention relates to an electrically heated honeycomb body characterized in that the contact portion is brazed.

Hereinafter, a technical configuration and an embodiment of the present invention will be described with reference to the drawings. It goes without saying that the present invention is not limited to the illustrated one.

First, the relationship between the electrically heated honeycomb body (EHH) of the present invention and the exhaust gas purifying apparatus (A) will be described. Generally, the electrically heated honeycomb body (EHH) having a pre-heater function of the present invention is used by being incorporated in an exhaust gas purifying apparatus (A) in a mode shown in FIG. FIG. 15 shows an electrically heated honeycomb body (EHH).
FIG. 2 is a cross-sectional view in which a part of an exhaust gas purifying device (A) in which is incorporated is omitted. As shown in the figure, the exhaust gas purifying device (A) has an electrically heated honeycomb body (EHH) upstream of the exhaust gas and Pt, Pd, Rh on the downstream side in the exhaust gas flow direction (F). The main (main) catalyst (MC) supporting a catalyst for purifying exhaust gas such as a metal case (C ₁ )
It is arranged and arranged inside. Then, the electric heating type honeycomb body (EHH) are honeycomb bodies (H), the center electrode member (B _1), and while being constituted by the outer peripheral portion electrode member (B _2), these electrode materials (B _1, B ₂ ) is connected to the external power supply section (4) by conducting wires (41, 42). In the arrangement of the electrically heated honeycomb body (EHH), attention must be paid to insulation from other members, but this is omitted in FIG. 15 for simplicity. In the present invention, a catalyst may be supported on the honeycomb body (H) in order to improve the heater characteristics of the EHH as described later. In such a case, the main catalyst (MC) may be omitted. Needless to say. That is, in such a case, EHH
Will also serve as the function of the MC.

FIG. 16 is a front view of the honeycomb body (H) of the electrically heated honeycomb body (EHH) shown in FIG. As shown in FIG. 16, a honeycomb body (H), which is a main component of the electrically heated honeycomb body (EHH) of the present invention, includes a flat metal strip (1) made of a thin metal plate and a corrugated web. It is manufactured by winding and laminating the members (2) so as to abut each other. Thereby, a large number of contact portions (12) of both strips (1, 2) and a large number of exhaust gas reticulated vent channels (cells) (3) are automatically formed. The outer peripheral electrode material (B ₂ ) also serves as a casing (C ₂ ) for the honeycomb body (H). (B ₂ = C ₂ ).

Next, the electrically heated honeycomb body (E) of the present invention
In (HH), a technical means for uniformly heating the inside of the honeycomb body (H), which is a main component when electricity is supplied, will be described.

In a honeycomb body (H) produced by winding and laminating a flat metal strip (1) made of a thin metal plate and a corrugated web (2) so as to abut each other, a flat web ( When brazing (brazing) the contact portion (12) of 1) and the corrugated strip (2), the brazed portion (brazed portion) and the non-brazed portion (non-brazed portion) If provided, a large difference in electrical resistance occurs between the two. Needless to say, the part that is not brazed is only a mechanical contact between the flat strip material (1) and the corrugated strip material (2).
The electrical resistance is higher than that in which both strips (1, 2) are completely joined by the brazing material. When the honeycomb body (H) manufactured by such a brazing mode is energized, most of the current flows to the brazed portions, and resistance heat is generated in the channels of the brazed portions. become. Further, in the band material (1, 2) of the non-brazed part of the present invention, an electric insulating layer is provided on the outer surface thereof,
For example, in the case where an insulating layer of Al ₂ O ₃ is provided, a current can be reliably passed through the brazing portion during energization, so that the resistance heating value can be accurately controlled in relation to the size of the brazing portion.

According to the present invention, the inside of the honeycomb body (H) is uniformly heated by electric conduction by utilizing the difference in resistance heat generation inside the honeycomb body (H) manufactured under the above-mentioned brazing mode. Like that. Hereinafter, a brazing mode applied to the honeycomb body (H) according to the present invention for uniformly heating the inside of the honeycomb body (H) at the time of energization will be described with reference to the drawings.

FIGS. 1 to 3 show a honeycomb body (H) of the present invention.
It is a figure for explaining the brazing mode of the 1st example applied to (1). 1, the present invention is a cross-sectional view through the center electrode material to (B ₁₎ of the electrically heated honeycomb body (EHH), the outer peripheral portion of the honeycomb body from the center electrode member (B ₁₎ (H) The resulting cross section (5) is shown. In the first embodiment, the cross section (5) is divided into a brazing plane (51) and a non-brazing plane (52) as shown in FIG. In FIG. 1,
The brazing plane (51) is a hatched portion. That is, on the cross section (5) extending from the central electrode material (B ₁ ) in the axial direction of the honeycomb body (H) to the outside of the honeycomb body (H) in contact with the outer peripheral electrode material (B ₂ ), the outer peripheral electrode is formed. The plane (51) where the ratio of the contact portion (12) brazed in the direction from the material (B ₂ ) to the central electrode material (B ₁ ) is large,
A line segment (a) in contact with the outer peripheral electrode material (B ₂ ) at one end of the honeycomb body (H), and a center electrode material at the other end of the honeycomb body (H) from the line segment (a). Is divided by a line segment (b) in which the distance from the curve continuously decreases gradually in a curved shape.

FIG. 2 is a front view of the electrically heated honeycomb body (EHH) shown in FIG. 1 as viewed from the front (Hf) of the honeycomb body. FIG. 3 is a front view of the electrically heated honeycomb body (EHH) shown in FIG. 1 as viewed from the rear (Hb) of the honeycomb body. 2 to 3, a hatched portion having a width (W) indicates a brazing portion (6), and a white portion indicates a non-brazing portion (7). And the brazing part (6)
(In the direction perpendicular to the paper surface in FIG. 2) is the cross-section (5
It covers the entire width (l ₀ ) of the honeycomb body including 1).

That is, the manner of brazing the honeycomb body (H) is performed as follows. First, as shown in FIG. 1, the central electrode material (B ₁ ) in the axial direction of the honeycomb body (H).
And one section (5) including a plane reaching the outer peripheral surface of the honeycomb body (H), and is included in the section (5);
In addition, from the outer peripheral portion of the honeycomb body (H) to the central electrode material (B ₁ )
The cross section (51) in which the ratio of the contact portion (12) between the flat strip material (1) and the corrugated strip material (2) is increased in the direction of, is defined as shown in FIG. ), A space region (Z) having a desired width (W) is defined, and the contact portion (12) between the flat band material (1) and the corrugated band material (2) existing in the space region (Z) is defined. ). Needless to say, the brazing portion (6) indicated by the hatched portions in FIGS.
Corresponds to the spatial region (Z). According to the above-described brazing mode, the power supply from the external power supply unit (4) causes the respective band members ( ₁ ) to be positioned near the outer peripheral electrode material (B ₂ ) and the central electrode material (B ₁ ). , 2) and the current density flowing through the contact portions (12) of the strips (1, 2) can be made substantially the same, and the inside of the honeycomb body (H) can be uniformly heated and heated. .

In the present invention, it goes without saying that the cross section (5) including the cross section (51) may be a flat surface or a curved surface having a desired shape. Further, as shown in FIG. 2, four planar cross-sections (5) are defined in the honeycomb body, and the spatial region (Z) is defined at a symmetrical position of 90 ° about the center electrode material. . In the present invention, the angle (α) formed by the symmetric space region (Z)
Is defined as 360 ° / n (where n is an integer of 2, 3,...), And n corresponds to the number of cross sections. In the present invention, it is needless to say that the spatial regions (Z) are not only symmetrically arranged but also asymmetrically arranged as will be shown in the embodiments described later. .

In the present invention, according to many experiments by the present inventors, the length (l ₁ ) of the line segment (a) shown in FIG. 1 is equal to the length (l ₁ ) of the entire width of the honeycomb body (H). ₀ ),
From the outer diameter (D) of the honeycomb body (H) and the outer diameter (d) of the center electrode material (B ₁ ) shown in FIG. . _{l 0/5 · d / D} ≦ l 1 ≦ 5l 0 · d / D The equation, when D is larger outer circumference electrode member (B ₂₎
The surface area of the larger, it must be set small l _1, also means that the surface area of the central electrode member when d increases (B ₂₎ may be increased to l ₁ because increased I have. Further, the relational expression takes into account the influence of the length (l ₀ ) of the entire width of the honeycomb body (H), and l ₁ can be rationally set by the relational expression.

Further, the desired width (W) and the center electrode member relationship of the outer diameter of (B ₁₎ (d), and the center electrode member outer diameter (d) and the honeycomb body (B ₁₎ (H) Outer diameter of (D)
According to the experiments performed by the present inventors, it is clear that the relationship (see FIG. 2) is preferably determined by the following expressions (1) and (2). Thereby, W can be set rationally. d / 5 ≦ W ≦ 5d (1) D / 15 ≦ d ≦ D / 5 (2) Note that the above relational expression is only a rough guide, and that the center electrode material (B ₁ ) If the value of the large width (W) is adopted with respect to the outer diameter (d), the current density in the vicinity of the central electrode material (B ₁ ) increases, so that abnormal heating, melting and the like of the part are caused. You have to be careful. In addition, the brazing aspect of the honeycomb body (H) of the present invention shown in FIGS.
d.

In the present invention, a flat metal strip (1) used for manufacturing the honeycomb body (H) constituting the electrically heated honeycomb body (EHH) is an ordinary metal monolith type main catalyst. The strip used in the production of the carrier matrix (MC), for example chrome steel (chrome 13-25
%), Heat-resistant stainless steel such as Fe-Cr 20% -Al 5%, or heat-resistant stainless steel to which rare earth is added to improve oxidation resistance.
A band of 04 mm to 0.1 mm is used. Further, as the corrugated sheet material (2), one obtained by corrugating the flat sheet material (1) so as to have a predetermined substantially sine wave or substantially trapezoidal wave is used. In addition, a Ni-Cr alloy, a Ni-Cr-Fe alloy, a Ni-Cr-Al-Fe alloy, etc. are used in consideration of the electrical conductivity of the honeycomb body (H) at a high temperature.

In particular, in the present invention, in order to improve the heater characteristics of the electrically heated honeycomb body (EHH) as described later, the honeycomb body (H) is used by supporting an exhaust gas purifying catalyst on the wall surface thereof. be able to. In such a case, the members constituting the honeycomb body (H), that is, those in which Al is contained in the flat band material (1) and the corrugated band material (2), or an Al layer is provided on the surface thereof. Heat the thing,
A whisker-like or mushroom-like alumina (Al ₂ O ₃ ) layer is preferably deposited on the surface.
The whisker-like alumina layer is preferable because it can firmly hold a washcoat layer for supporting an exhaust gas purifying catalyst such as Pt, Pd, and Rh as described later.

As described above, in the electrically heated honeycomb body (EHH) of the present invention, in order to improve the heater characteristics (heating characteristics), the electrically heated honeycomb body (EHH) is used.
The exhaust gas purifying catalyst can be supported on the wall surface of the honeycomb body (H), which is a main component of H). As is well known, HC (hydrocarbon compounds) and CO (carbon monoxide) in exhaust gas are converted into oxidation catalysts (Pt,
Pd, Cr, V, Cu, etc.)
Detoxified by O ₂ and H ₂ O. An oxidation-reduction (ternary) catalyst (Pt-Rh, Pt-Rh) for simultaneously purifying HC, CO and NOx exhausted in exhaust gas near the stoichiometric air-fuel ratio.
Pd-Rh type) is well known, and these exhaust gas components are oxidized to CO ₂ or H ₂ O or N ₂
It is reduced to. In addition, even in the three-way catalyst system, the catalytic reaction proceeds exothermically as a whole.

In the present invention, the purpose of supporting the exhaust gas purifying catalyst on the side of the honeycomb body (H) is to improve the purifying ability of the entire exhaust gas purifying apparatus (A), while at the same time as mentioned above, The effective use of the calorific value is based on the fact that the calorific value is used for improving the heater characteristics. In the present invention, the catalyst supported on the wall surface of the honeycomb body (H) is preferably an oxidation catalyst in view of the magnitude of the calorific value, as can be seen from the above-mentioned catalytic reaction. However, oxidation reduction (three-way catalyst) (a three- way catalyst). In addition,
The method for supporting these catalyst components will be described in connection with the main catalyst (MC) described later.

The electrically heated honeycomb body (EHH) of the present invention
The arrangement relationship (energization connection) between the power supply and the external power supply section (4) may be made as shown in FIG. 1, and may be made as shown in FIG. 15 when viewed from the entire exhaust gas purification device (A). In the present invention, although not shown, the power supply from the external power supply unit (4) to the electrode materials (B ₁ , B ₂ ) may be performed for a limited time by a timer, or a desired time may be supplied to the honeycomb body. The temperature of the honeycomb body or the temperature of the exhaust gas may be measured by a sensor (such as a thermocouple) attached to the site, and the temperature may be turned on and off at a desired set value. The external power supply (4)
Although a DC power supply is illustrated as an example, it goes without saying that an AC power supply may be used. In the present invention, it goes without saying that the line segment (b) of the first and second embodiments does not have to reach the end portion (H ₁ ) of the honeycomb body (H). This is the same in the following embodiments.

FIG. 4 is a view for explaining the brazing mode of the second embodiment applied to the honeycomb body (H) of the present invention, and corresponds to FIG. In the second embodiment,
Compared with the first embodiment, the line segment (b) is different in that the distance from the center electrode material (B ₁ ) is intermittently (stepwise) gradually reduced. The configuration is the same. By such a brazing mode, it is possible to make the current densities in the vicinity of the two electrode materials (B ₁ , B ₂ ) substantially the same during energization. In the present invention, it goes without saying that the line segment (b) of the first and second embodiments does not have to reach the end portion (H ₁ ) of the honeycomb body (H). This is the same in the following embodiments.

FIG. 5 is a view for explaining the brazing mode of the third embodiment applied to the honeycomb body (H) of the present invention, and corresponds to FIG. In the third embodiment,
Compared to the first embodiment, the line segment (a) is set at both ends of the honeycomb body (H), and the line segment (b) is formed in a downwardly convex parabolic shape. Although different, the other technical configurations are the same. By such a brazing mode, it is possible to make the current densities in the vicinity of the two electrode materials (B ₁ , B ₂ ) substantially the same during energization. In addition, as shown in FIG. 5, the line segment (b) is not formed into a downwardly convex parabolic curve, but
It goes without saying that the distance from the central electrode material (B ₁ ) may be gradually and intermittently (stepwise) from both ends of the honeycomb body (H) toward the central part.

FIG. 6 is a view for explaining a brazing mode of a fourth embodiment applied to the honeycomb body (H) of the present invention.
This corresponds to FIGS. 1 and 4 and 5. In the fourth embodiment, as compared with the first embodiment, the line segment (a) is set at the outer peripheral portion of the honeycomb body (H) and substantially at the center in the axial direction, and the line segment (b ₁₎ , B ₂ ) from the line segment (a) toward both ends of the honeycomb body (H) in the center electrode material (B ₁ ).
The difference is that the distance from is set to be gradually reduced, but the other technical configurations are the same. With such a brazing mode, both electrode materials (B ₁ ,
The current density in the vicinity of B ₂ ) can be made substantially the same. The line segment (b ₁ , b ₂ ) is not formed as a continuous curve as shown in FIG. 6, but one or both of them are continuously (stepwise) changed in distance from the center electrode material (B ₁ ). It goes without saying that the value may be gradually reduced.

FIG. 7 is a view for explaining a brazing mode of a fifth embodiment applied to the honeycomb body (H) of the present invention, and corresponds to FIG. The fifth embodiment is
Compared with the first embodiment, two planar cross sections (5) shown in FIG. 1 are set, and an angle α
= 180 °, but the other technical configurations are the same. By such a brazing mode, it is possible to make the current densities in the vicinity of the two electrode materials (B ₁ , B ₂ ) substantially the same during energization.

FIG. 8 is a view for explaining a brazing mode of a sixth embodiment applied to the honeycomb body (H) of the present invention, and corresponds to FIG. In the sixth embodiment,
Compared to the first embodiment, the first embodiment has W> d
However, the sixth embodiment differs in that W <d, but the other technical configurations are the same. By such a brazing mode, both electrode materials (B ₁ , B ₂ )
Can be made approximately the same in the current density in the vicinity.

FIG. 9 is a view for explaining the brazing mode of the seventh embodiment applied to the honeycomb body (H) of the present invention, and corresponds to FIG. The seventh embodiment,
Compared with the first embodiment, four planar cross-sections (5) shown in FIG. 1 are set inside the honeycomb body, α = 45 °, and W <d. Although different, the other technical configurations are the same. By such a brazing mode, it is possible to make the current densities in the vicinity of the two electrode materials (B ₁ , B ₂ ) substantially the same during energization.

FIG. 10 is a view for explaining the brazing mode of the eighth embodiment applied to the honeycomb body (H) of the present invention, and corresponds to FIG. The eighth embodiment includes a cross section (5) including the cross section (51) of the first to seventh embodiments.
Is a plane shape, the cross section (5) is defined as a curved surface, and the curved surface defines the space area (Z). The eighth embodiment has exactly the same configuration as that of the fifth embodiment shown in FIG. 7 except that the cross section (5) is a curved surface.

FIG. 11 is a view for explaining a brazing mode of a ninth embodiment applied to the honeycomb body (H) of the present invention. The spatial region (Z) of the first to fifth embodiments has an angle (α) between the spatial regions (Z) of 360 ° / n with respect to the center electrode material (B ₁ ). It is defined in a symmetrical position. On the other hand, the ninth embodiment shown in FIG. 11 is defined at an asymmetric position. Other technical configurations are exactly the same as the first embodiment.

FIG. 12 is a view for explaining a brazing mode of a tenth embodiment applied to the honeycomb body (H) of the present invention. In the tenth embodiment, a space region (Z ₁ ) having a predetermined width (W ₁ ) including a predetermined planar cross section (5) defined in a honeycomb body (H) and another planar cross section (5) are formed. And a spatial area (Z ₂ ) having a predetermined width (W ₂ ) (Z = Z ₁ +
Z ₂ ) (W ₁ ≠ W ₂ ). Other technical configurations are exactly the same as the first embodiment.

FIG. 13 shows an eleventh embodiment of the present invention. The eleventh embodiment is exactly the same as the first embodiment except for the point that the cross-sectional shape of the honeycomb body (H) is a race track shape.

FIG. 14 shows a twelfth embodiment of the present invention. The twelfth embodiment is exactly the same as the first embodiment except for the point that the cross-sectional shape of the honeycomb body (H) is substantially triangular.

In the present invention, the brazing material of the first to twelfth embodiments may be supplied by an appropriate method. For example,
When the flat strip material (1) and the corrugated strip material (2) are wound and formed into a honeycomb body (H), at least one of the two strip materials (1, 2) is required. What has supplied the brazing material by coating to the site may be used. Or,
When winding the strip, the brazing material coating liquid may be supplied to a necessary portion of the strip while synchronizing with the winding speed. From the viewpoint of saving of the brazing material, durability of the honeycomb body, and the like, it is preferable that the brazing material is supplied to a required portion of the corrugated strip (2) at the top (peak or valley). In the present invention, in order to enhance the electrical insulation of the non-brazed portion other than the brazed portion, the oxidized brazed honeycomb body, or coating the site with alumina slurry,
In addition, a heat treatment may be performed to form an electrically insulating alumina coating layer on the portion. The formation of the above-mentioned alumina coating layer may be carried out at the same time when the flat strip material (1) and the corrugated strip material (2) are wound and formed into a honeycomb body (H). For example, an alumina slurry may be applied to a portion to which the brazing material is not supplied at the time of winding forming.

The electrically heated honeycomb body (EHH) of the present invention
Is generally the main catalyst (MC) as shown in FIG.
It is arranged and used at the front of the vehicle. Hereinafter, the main catalyst (MC) will be described. Exhaust gas purification device (A)
The other main component of the main catalyst (MC) is
It may be a ceramic monolith type,
Alternatively, a monolithic type made of metal may be used. These may be manufactured according to a conventional method, for example, by manufacturing a main catalyst supporting base which is a precursor of the main catalyst (MC), and supporting an exhaust gas purifying catalyst on this.
Hereinafter, a method of producing a metal (metal) monolith-type main catalyst supporting base will be described, but the main catalyst supporting base applicable to the present invention is not limited thereto. The method for supporting the catalyst will be described later.

First, there is a main catalyst carrier of a winding type having a circular cross section. This is manufactured by laminating a heat-resistant, thin metal plate-shaped flat strip (1) and a corrugated strip (2) so that they are in contact with each other, and winding and laminating them in a spiral. You. A large number of mesh-shaped vent holes (cells) (3) serving as exhaust gas passages are automatically formed by winding and laminating. The wound-type honeycomb body (H), which is a main component of the above-described electrically heated honeycomb body (EHH), is also manufactured by this method. More specifically, it may be manufactured as follows. Fe-Cr 20% -Al 5%-
0.02% thickness of 0.02% heat-resistant steel, 38mm wide
Is passed between the forming gears to form a corrugated strip having a pitch width (3.0 mm) and a wave height (1.4 mm). Next, the flat strip and the corrugated strip manufactured by corrugating the flat strip are piled on each other, and the end is inserted into the slit portion of the slit-shaped wound forming rod,
For example, a metal main catalyst supporting body having an outer diameter of 70 mm and having a large number of mesh-shaped vent holes (cell density of 300 cpsi) in the axial direction may be formed by batch winding and lamination.

Next, there is a main catalyst supporting base of a hierarchical type having a circular cross section. This is manufactured by laminating a flat strip (1) and a corrugated strip (2) made of a heat-resistant thin metal plate in a hierarchical manner so as to abut each other.

There is a radial type main catalyst supporting base having a circular cross section. In this method, a heat-resistant flat metal strip (1) and a corrugated steel strip (2) are brought into contact with each other to form a purifying element (E), and a desired number of the purifying elements (E) is fixed. It is manufactured by extending radially from the axis (S) as a starting point.

There is an S-shaped main catalyst supporting base having a circular cross section. This is a heat-resistant flat metal strip made of a thin metal plate and a corrugated steel strip are brought into contact with each other to form a purifying element (E), and the purifying element (E) is formed into a flat steel strip on the outermost surface. Each of the purification elements (E) is stacked in a hierarchical manner, and each purification element (E) is bent in the opposite direction about two fixed points (S ₁ , S ₂ ) set on the upper and lower outermost surfaces, that is, each purification element (E ) Is bent into a substantially S-shaped curve.

In order to carry a catalyst for purifying exhaust gas such as Pt, Pd, Rh or the like on the main catalyst carrier having various structures manufactured as described above, a usual method may be adopted. For example, first, a catalyst supporting layer for supporting the catalyst on the wall surface of the main catalyst supporting base having a honeycomb structure is formed. To this, a slurry in which activated alumina (γ-Al ₂ O ₃ ) powder and alumina sol were mixed was applied,
What is necessary is just to heat-process to 0 degreeC. Next, in order to support a catalyst such as a Pt, Pd, Rh catalyst or the like on the catalyst supporting layer formed in this manner, a catalyst component may be supported by a normal method such as impregnation. The main catalyst (MC) is manufactured as described above.

The electrically heated honeycomb body (EHH) of the present invention
Is generally fixed together with the main catalyst (MC) in a metal case (C ₁ ) together with the main catalyst (MC) for manufacturing an exhaust gas purifying apparatus (A) as shown in FIG. Such a metal case (C ₁ ) is for accommodating and fixing the above-mentioned electrically heated honeycomb body (EHH) and the main catalyst (MC) inside. However, there is no restriction on its shape. As the material of the metal case (C ₁ ), the same type of heat-resistant steel as that of the main body supporting the main catalyst may be used, or a material having more excellent heat and corrosion resistance may be used. In addition, the metal material of the outer part has a double structure that is more heat and corrosion resistant than the inner part,
Specifically, ferrite stainless steel may be used for the inner part and austenitic stainless steel may be used for the outer part.

[0047]

The electric heating type honeycomb body (EH) of the present invention
H) generally includes a metal case (C) as a main component (pre-catalyzer) of the exhaust gas purification device (A).
_Although it is disposed and used upstream of the main catalyst (MC) in ₁ ), it can be used instead of the main catalyst (MC) (as a main characterizer). And the electrically heated honeycomb body (EHH) of the present invention
, The main component of which is the honeycomb body (H)
Employs a novel brazing means so that the temperature distribution of the heat generating portion is uniform and sufficient resistance heating can be obtained at the time of energization. Further, in the honeycomb body (H), an exhaust gas purifying catalyst can be carried on a wall surface thereof in order to improve heater characteristics (heating characteristics).

Therefore, the following excellent effects are achieved in the present invention. (1) Since the exhaust gas is uniformly heated in the electrically heated honeycomb body (EHH) and heated to a temperature suitable for the catalytic reaction, the exhaust gas purification capacity at the time of gold start, which is particularly problematic in the exhaust gas treatment, is improved. Can be greatly improved. (2) When the exhaust gas purifying catalyst is carried on the honeycomb body (H) of the electrically heated honeycomb body (EHH), the exhaust gas purifying performance of the entire exhaust gas purifying apparatus (A) is improved as well as the heater characteristics. Can be done. (3) Since the constituent members of the electrically heated honeycomb body (EHH) are not locally heated, it is possible to prevent a decrease in vibration resistance (mechanical strength) due to deterioration of the members. (4) Since the electrically heated honeycomb body (EHH) itself serves as a heater, it is not necessary to separately manufacture and arrange a heater material. (5) In the honeycomb body (H), which is a main component of the electric heating type honeycomb body (EHH), the flat strip material (1) and the corrugated strip material (1) at the center of the honeycomb body and in the vicinity thereof. Since the contact portion (12) of (2) has a higher ratio of brazing than other portions, scoping (protrusion) normally seen in the central portion of this type of honeycomb body is prevented, and it is excellent over a long period of time. The heater function can be exhibited.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to a first embodiment of the present invention.

FIG. 2 is a frontal front view of the electrically heated honeycomb body according to the first embodiment of the present invention.

FIG. 3 is a rear front view of the electrically heated honeycomb body according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view of an electrically heated honeycomb body (EHH) for describing a brazing mode according to a third embodiment of the present invention.

FIG. 6 is a cross-sectional view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to a fourth embodiment of the present invention.

FIG. 7 is a cross-sectional view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to a fifth embodiment of the present invention.

FIG. 8 is a cross-sectional view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to a sixth embodiment of the present invention.

FIG. 9 is a cross-sectional view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to a seventh embodiment of the present invention.

FIG. 10 is a cross-sectional view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to an eighth embodiment of the present invention.

FIG. 11 is a sectional view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to a ninth embodiment of the present invention.

FIG. 12 is a cross-sectional view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to a tenth embodiment of the present invention.

FIG. 13 is a cross-sectional view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to an eleventh embodiment of the present invention.

FIG. 14 is a cross-sectional view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to a twelfth embodiment of the present invention.

FIG. 15 is an electrically heated honeycomb body (EHH) of the present invention.
FIG. 2 is a cross-sectional view in which a part of an exhaust gas purifying apparatus incorporating the same is omitted.

FIG. 16 shows an electrically heated honeycomb body (EHH) of the present invention.
FIG.

[Explanation of symbols]

A: Exhaust gas purification device MC: Main catalyst EHH: Electric heating type honeycomb body H: Honeycomb body forming an electric heating type honeycomb body B _1: Central electrode material B ₂ Outer electrode material C ₁ , C ₂ Casing F Exhaust gas flow direction 1 Flat band material 2 ………… Corrugated strip 12 ………… Contact portion between flat plate and corrugated strip 3 ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………. External power supply 41, 42 Lead wire 5 Cross section of honeycomb body 51 Brazing plane 52 Non-brazing plane 6 Brazing plane Brazing part 7 Non-brazing part a, b ……… Line segment

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B01J 21/00-37/36 B01D 53/86 F01N 3/00

Claims (3)

(57) [Claims] 1. A casing and a central portion are formed as an outer peripheral electrode material and a central electrode material, respectively, and a flat metal strip made of a thin metal plate and a corrugated metal strip are weighted in the casing so as to abut each other. The honeycomb body manufactured by stacking is fixed in the casing, the electrodes are energized, and the electric heating type honeycomb body has a structure capable of generating heat, wherein the honeycomb body includes: (i) an axial center of the honeycomb body. A flat or curved section extending from the outer electrode material to the outer peripheral portion of the honeycomb body, and a contact portion between the flat plate material and the corrugated band material in a direction from the outer peripheral portion of the honeycomb body to the central electrode material. (Ii) defining at least two or more spatial regions (Z) having a predetermined width (W) including the cross section in the honeycomb body, and (iii) defining the space in the honeycomb body. Flat strip and corrugated sheet in zone (Z) An electrically heated honeycomb body, characterized in that the abutting portion of the strip is brazed. 2. A cross section in which the ratio of the abutting portion between the flat band material and the corrugated band material increases in the direction from the outer peripheral portion of the honeycomb body to the central electrode material is formed at one end of the honeycomb body at the outer peripheral electrode. And a line segment (b) in which the distance from the center electrode material in the direction of the other end of the honeycomb body from the line segment (a) decreases gradually from the line segment (a). Item 2. An electrically heated honeycomb body according to Item 1. 3. The electrically heated honeycomb body according to claim 1, wherein the surface of the strip material at the non-brazed portion of the honeycomb body has an electrically insulating layer.