JP3312933B2 - 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 solving the problem, 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.

Therefore, a conventional exhaust gas purifying apparatus incorporating an electric heating type honeycomb body having a pre-heater function (note that the outline of the entire apparatus is the same as that shown in FIG. In FIG. 11), the inside is not uniformly heated and heated by energization, and the exhaust gas passing through the inside is heated unevenly 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 an outer peripheral electrode material and a 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. In the electric heating type honeycomb body having a structure in which a honeycomb body manufactured by stacking the honeycomb body is fixed in the casing, and each electrode is energized and capable of generating heat, a flat strip material constituting the honeycomb body as the honeycomb body The brazing of the contact portion between the honeycomb body and the corrugated strip selects at least one cross section including a flat surface or a curved surface extending from the central electrode material in the axial direction of the honeycomb body to the outer peripheral portion of the honeycomb body; A desired width (W) including the cross section was selected on the front of the body, and the cross section was translated within the desired width (W) to form a spatial trajectory, and the contact portion in the spatial trajectory was brazed. Electrical processing characterized by using It relates formula honeycomb body.
In other words, the present invention provides the electrically heated honeycomb body according to the present invention, wherein the honeycomb body comprises: (i) a flat or curved surface extending from an axial center electrode material of the honeycomb body to an outer peripheral portion of the honeycomb body. (Ii) at least two or more spatial regions (Z) having a desired width (W) including the cross-section are defined in the honeycomb body; and (iii) the spatial region (Z) is defined in the honeycomb body. Wherein the contact portion between the flat band member and the corrugated band member is brazed, and wherein the honeycomb structure is an electric heating type honeycomb body.

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. 11 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). It should be noted that 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. 11 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. 12 is a front view of the honeycomb body (H) of the electrically heated honeycomb body (EHH) shown in FIG. As shown in FIG. 12, a honeycomb body (H), which is a main component of the electrically heated honeycomb body (EHH) of the present invention, generally includes a flat metal strip (1) made of a thin metal plate and a corrugated sheet. It is manufactured by winding and laminating the strips (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, when an electric insulating layer, for example, an insulating layer of Al ₂ O ₃ is provided on the outer surface thereof, the current is reliably applied to the brazed part during energization. Therefore, the amount of heat generated by the resistance 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 and 2 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, reaches the outer periphery of the central portion electrode material of the electrically heated honeycomb body of the present invention (EHH) (B ₁₎ a cross-sectional view through the honeycomb body from the center electrode member (B ₁₎ (H) The cross section (5) is shown. FIG. 2 is a front view of the electrically heated honeycomb body (EHH) shown in FIG. In FIG. 2, a hatched portion having a width (W) indicates a brazing portion (6), and a white background portion indicates a non-brazing portion (7). The brazing portion (6) extends over the entire width ( _lo ) of the honeycomb body including the cross section (5) (in a direction perpendicular to the paper surface in FIG. 2).

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 a spatial area (Z) of a desired width (W) including a cross section (5) including a plane extending to the outer peripheral surface of the honeycomb body (H) and including the cross section (5) as shown in FIG. Stipulates,
The contact portion (12) of the flat strip (1) and the corrugated strip (2) existing in the space area (Z) is brazed. Needless to say, the brazing portion (6) indicated by hatching in FIG. 2 coincides with the spatial region (Z). According to the brazing mode as described above, the outer peripheral electrode material (B ₂ )
The current density flowing in each of the strips (1, 2) and the contact portion (12) of each of the strips (1, 2) is substantially the same in the vicinity of the central electrode material (B ₁ ). Thus, 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) may be a flat surface or a curved surface having a desired shape. As shown in FIG. 2, four planar cross-sections (5) are defined in the honeycomb body, and the spatial region (Z) is 90% centered on the central electrode material.
It is specified in the symmetric position of °. In the present invention, the angle (α) formed by the symmetrical spatial region (Z) is defined by 360 ° / n (where n is an integer of 2, 3,...), Where n corresponds to the number of cross sections. It is. 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. .

[0020] In the present invention, the outer diameter (d) and the honeycomb body of the relationship between the outer diameter (d) of the desired width (W) and the center electrode member (B _1), and the center electrode member (B ₁₎ ( As for the relationship between the outer diameter (D) (see FIG. 2) of H), it has been found from experiments by the present inventors that it is preferable to relate them by the following equations (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. The brazing mode of the honeycomb body (H) of the present invention shown in FIGS.
d.

In the present invention, as the flat band material (1) used for manufacturing the honeycomb body (H) constituting the electrically heated honeycomb body (EHH), an ordinary metal monolith type main catalyst is used. The strip used in the production of the carrier matrix (MC), for example chrome steel (chrome 13-25
%), A heat-resistant stainless steel such as Fe-Cr 20% -Al 5% or a heat-resistant stainless steel to which a rare earth is added to improve oxidation resistance.
Use a band of 4 mm to 0.1 mm. 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), a catalyst for purifying exhaust gas is supported on the wall surface of the honeycomb body (H), as described later. 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 performance 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 unit and the external power supply unit (4) may be performed as shown in FIG. 1, and may be performed as shown in FIG. 11 when viewed from the entire exhaust gas purifying apparatus (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.

FIG. 3 is a view for explaining a brazing mode of a 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, two planar cross-sections (5) shown in FIG. 1 are set, and the angle formed by the spatial region (Z), 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. Therefore, the inside of the honeycomb body (H) can be uniformly heated and heated by such a brazing mode.

FIG. 4 is a view for explaining a 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 first embodiment has W> d
The third embodiment differs from the third embodiment 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. 5 is a view for explaining the brazing mode of the fourth embodiment applied to the honeycomb body (H) of the present invention, and corresponds to FIG. The fourth embodiment is
Compared with the first embodiment, eight planar cross sections (5) shown in FIG. 1 are set inside the honeycomb body, α = 45 °, and W <d. Although different in point, the other technical configurations are the same. Even in 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. 6 is a view for explaining a brazing mode of a fifth embodiment applied to the honeycomb body (H) of the present invention.
This corresponds to FIG. The fifth embodiment is different from the first to fourth embodiments in that the cross section (5) is flat.
The cross section (5) is a curved surface, and this curved surface is used as a spatial region (Z).
Is defined. The fifth embodiment has exactly the same configuration as that of the second embodiment shown in FIG. 3, except that the cross section (5) is a curved surface.

FIG. 7 is a view for explaining a brazing mode of a sixth 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 specified in the target position. On the other hand, the sixth embodiment shown in FIG. 7 is defined in an asymmetric position. Other technical configurations are exactly the same as the first embodiment.

FIG. 8 is a view for explaining a brazing mode of a seventh embodiment applied to the honeycomb body (H) of the present invention.
In the seventh embodiment, a spatial region (Z ₁ ) having a predetermined width (W ₁ ) including a predetermined planar cross section (5) defined in the honeycomb body (H) is used.
₁ ) and a spatial area (Z ₂ ) having a predetermined width (W ₂ ) including another planar cross section (5) (Z = Z ₁ + Z ₂ ) (W ₁ ≠ W _2). ). Other technical configurations are exactly the same as the first embodiment.

FIG. 9 shows an eighth embodiment of the present invention. In the eighth embodiment, the sectional shape of the honeycomb body (H) is
Other technical configurations are exactly the same as in the first embodiment except that they are of a race track shape.

FIG. 10 shows a ninth embodiment of the present invention. The ninth embodiment is exactly the same as the first embodiment except that the cross-sectional shape of the honeycomb body (H) is substantially triangular.

In the present invention, in order to perform the brazing of the first to ninth embodiments, the brazing material may be supplied to the strip (1, 2) 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 used. The brazing material may be supplied to the necessary parts by coating. Alternatively, the brazing material coating liquid may be supplied to a necessary portion of the band material while synchronizing with the winding speed at the time of winding the band material. 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 brazed honeycomb body is oxidized, or the portion is coated with alumina slurry, and subjected to a heat treatment to heat the portion. May be formed with an electrically insulating alumina coating layer. 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 flat strip (1) and a corrugated strip (4) made of a heat-resistant, thin-walled metal sheet so as to abut 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.

[0042]

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).

Accordingly, 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 front view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to the first embodiment of the present invention.

FIG. 3 is a front view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to a second embodiment of the present invention.

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

FIG. 5 is a front view of an electrically heated honeycomb body (EHH) for explaining a brazing mode according to a fourth embodiment of the present invention.

FIG. 6 is a front view of an electric heating type honeycomb body (EHH) for explaining a brazing mode according to a fifth embodiment of the present invention.

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

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

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

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

FIG. 11 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. 12 is 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 6 Brazing part 7 Non-brazing part

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B01J 21/00-37/36 B01D 53/86 F01N 3/00

Claims (2)

(57) [Claims] 1. A casing and a central portion are respectively used as an outer peripheral electrode material and a central electrode material, and a flat strip made of a thin metal plate and a corrugated strip are mutually applied around the central electrode material. A honeycomb body manufactured by stacking so as to be in contact with each other is fixed in the casing, and each electrode is energized to generate heat. In the electric heating type honeycomb body, the honeycomb body includes: (i) a shaft of the honeycomb body; A cross section composed of a flat or curved surface extending from the central electrode material in the direction to the outer peripheral portion of the honeycomb body is defined in the honeycomb body. (Ii) At least two or more spatial regions (Z) having a desired width (W) including the cross section ) Is defined in the honeycomb body, and (iii) a contact portion between the flat band material and the corrugated band material in the space area (Z) is brazed. Type honeycomb body. 2. The electrically heated honeycomb body according to claim 1, wherein a surface of the strip material at a non-brazed portion of the honeycomb body has an electrically insulating layer.