JPH06317146A - Exhaust emission control device - Google Patents

Abstract

PURPOSE:To provide an excellent heater characteristic by constituting a honeycomb body of conductive flat or corrugated bands each made of thin metal and corrugated or flat sheets each made of glass fiber or ceramics, the honeycomb body being disposed on the windward side and having a heater function, and the bands and the sheets being stacked on each other, and providing the bands with electrode terminals. CONSTITUTION:A honeycomb body 1 and a main catalyst carrier base 2 are enclosed in a metallic case 3. The honeycomb body 1 is provided on the windward side of the flow F of exhaust gas and is connected to a power source portion 6 such as a battery by means of lead wires 4,5. The honeycomb body 1 is used by combining a flat band made of a thin thickness metallic plate, or a flat sheet made of glass fiber or ceramics, and a corrugated band made of a thin thickness metallic plate or a corrugated sheet made of glass fiber or ceramics, in such a way that either the flat or corrugated member is made of a metallic plate so that it can conduct, and the bands or sheets are stacked on each other in an abutting manner and are wound into a spiral. An excellent heater characteristic is thus obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly comprises a catalyst carrying base for carrying an exhaust gas purifying catalyst, which is interposed in the middle of an exhaust pipe as a means for purifying exhaust gas of an automobile. Exhaust gas purification device More specifically, the present invention can significantly improve the major drawback of an exhaust gas purifying apparatus using this type of catalyst-supported base material, that is, the problem of low exhaust gas purification rate at engine start (cold start). The present invention relates to an exhaust gas purification device incorporating a heating means that can be used.

[0002]

2. Description of the Related Art Conventionally, a catalyst monolithic type using a ceramic material such as cordierite and a metal monolith type as a catalyst supporting base which is a main constituent member of an exhaust gas purifying apparatus of this type. A monolith type is known. Particularly in recent years, a metal monolith type has been actively researched and developed in terms of mechanical strength, durability, ventilation resistance, purification efficiency (miniaturization of device) and the like. In the following description, for convenience of description, the latter metal monolith type will be mainly described. A metal monolith type exhaust gas purifying apparatus generally stacks a flat plate-shaped strip made of a heat-resistant thin steel plate and a corrugated strip made by corrugating the thin steel plate so as to have mutual contact portions. However, a large number of mesh-like vent holes (hereinafter, also referred to as cells) for exhaust gas passages are formed in the axial direction, which are manufactured by stacking them in a spiral shape or by stacking them in layers. It is composed of a honeycomb-shaped laminated body (hereinafter referred to as a honeycomb body) and a cylindrical metal case having both ends opened for filling and fixing the honeycomb body. The honeycomb body and the metal case are formed so as to withstand thermal expansion and thermal stress that occur in a high temperature atmosphere of the exhaust gas itself and a high temperature atmosphere due to an exothermic reaction between the exhaust gas and the purification catalyst, and when the vehicle is running. It is firmly fixed by brazing or welding so that it can withstand the violent vibration of. It goes without saying that the abutting portions of the flat plate-shaped band member and the corrugated plate-shaped band member forming the honeycomb body are fixed by various methods.

The major problems in this type of exhaust gas purifying apparatus are as follows. That is, when the engine is started (at the time of cold start), the optimum temperature at which the exhaust gas purifying catalyst such as Pt, Pd, and Rh carried on the wall surface of the metal honeycomb body efficiently causes a catalytic reaction with the exhaust gas. This means that the conditions have not been reached, and most harmful substances such as CO (carbon monoxide) and HC (hydrocarbon compounds) emitted from the engine are not purified but are released into the atmosphere. .

Various proposals have been made in order to solve the problems at the time of starting the engine (at the time of cold starting). For example, (i) In Japanese Utility Model No. 63-67609,
In a converter using a ceramic monolith type as the main catalyst, a metal monolith catalyst coated with alumina on a metal carrier manufactured in advance in a honeycomb shape and provided with a current-carrying metal monolith catalyst is arranged in the vicinity of the exhaust gas upstream side of the catalyst. The installation method, (ii)
A method of arranging a far infrared heater on the outer periphery of the catalyst body, (i
ii) In Japanese Utility Model Publication No. 3-10022, a heating heater is provided on the front surface (upstream side of exhaust gas) of a monolith type catalyst, and a straightening plate for rectifying exhaust gas is provided on the front surface of the heater. Is proposed. However, in these conventional proposals, the honeycomb body is required to have a sufficiently high temperature to efficiently carry out the catalytic reaction, or the flow velocity distribution of the exhaust gas inside the honeycomb body has a particular relation to the honeycomb body. In view of the demand for rapid heating of the central part and the parts in the vicinity of the central part, it is not sufficient, or the cost is increased to solve it, so it is not sufficiently satisfactory. Absent.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention has been made to solve the problems found in the above-mentioned conventional honeycomb body. The present inventors have made various studies on a technique for raising the temperature of the honeycomb body, especially the entire inside of the honeycomb body, to a sufficiently high temperature rapidly at the time of cold start. In particular, the actual development 63 described in the prior art
In an electric heating type exhaust gas purifying apparatus of the type proposed in No. 67609, etc., the inventors have earnestly studied to improve a honeycomb body having a preheater function. As a result, the inventors of the present invention (i), as proposed in Japanese Utility Model Laid-Open No. 63-67609 described as the prior art,
For preheating, a honeycomb body is manufactured by stacking flat heat-resistant thin metal plate flat strips and corrugated strips so that they come into contact with each other, and then coating them with alumina to form a preheater. (It should be noted that the coating with alumina in the above-mentioned prior art is recognized to support the exhaust gas purification catalyst in the coating layer to be formed.), (Ii) Flat plate strip made of thin metal plate Rigid sheet material or flat sheet made of glass fiber or ceramics for either one of the flat plate-shaped strip material and the corrugated plate-shaped strip material rather than forming a honeycomb body with the strip material and the corrugated plate-shaped strip material It has been found that when the material is replaced with a new material, the resistance becomes large when energized, so that the amount of heat generated by resistance heating becomes large, and that this is extremely effective for exhaust gas purification at engine start (cold start). This has led to the formation. That is, in the case of (i), since the flat metal strip made of a thin metal plate and the corrugated metal strip forming the honeycomb body are in contact with each other, for example, a winding having electrode terminals at the center and the outer peripheral portion. In the case of a cylindrical honeycomb body of a type, it is impossible to obtain sufficient resistance heating because electricity easily flows through the abutting portion in the radial direction by energization, whereas in the case of (ii) above, electricity is not It has been found that sufficient resistance heating can be obtained for flowing in the winding direction of the flat strip or the corrugated strip, whereby the honeycomb body is heated to a sufficiently high temperature. The present invention intends to provide an electric heating type exhaust gas purifying apparatus having excellent heater characteristics based on the above findings.

[0006]

The present invention will be summarized as follows.
The present invention relates to an exhaust gas purifying device for purifying exhaust gas, which comprises a honeycomb body having a heater function on the windward side and a main catalyst supporting mother body on the leeward side with respect to an exhaust gas flow, and having the heater function. A honeycomb body having (i) (a) a thin metal plate that can be energized, or a corrugated plate material, and (b) a corrugated sheet material or a flat sheet material made of glass fiber or ceramics. And the flat plate-shaped strip and / or the corrugated strip-shaped strip having electrode terminals for energization. The present invention relates to a characteristic exhaust gas purifying device.

The technical construction and embodiments of the present invention will be described below with reference to the drawings. Needless to say, the present invention is not limited to the illustrated one.

FIG. 1 is a sectional view of an exhaust gas purifying apparatus (A) according to a first embodiment of the present invention. In FIG. 1, 1 is a honeycomb body having a heater function, 2 is a main catalyst supporting base, and 3 is a metal case for accommodating and fixing the honeycomb body (1) and the main catalyst supporting base (2). . As shown in FIG. 1, in the exhaust gas purifying apparatus (A) of the present invention, a honeycomb body (1) having a heater function and a main catalyst supporting matrix (2) are provided.
Is the honeycomb body (1) on the windward side with respect to the exhaust gas flow (F),
On the leeward side, the main catalyst supporting base (2) is arranged and fixed in the metal case (3). As shown in the figure, a gap space (S) is provided between the honeycomb body (1) having a heater function and the main catalyst supporting base body (2). In the present invention, the gap space (S) may be set arbitrarily and need not be provided. However, since the exhaust gas flow heated by the honeycomb body (1) having the heater function diffuses or becomes turbulent in the gap space (S), the temperature of the exhaust gas flow becomes more uniform, so that the gap space ( Providing S) is preferred. Further, the shape of the metal case (3) is not limited to the one that spreads in the shape of a cone at the inlet of the exhaust gas as shown in the figure, but may have any shape as will be described later.

First, the honeycomb body (1) having the heater function of the present invention will be described. The honeycomb body (1) of the present invention is manufactured by a usual method. The manufacturing method thereof is substantially the same as the case where the main catalyst supporting base material (2) described later is a metal monolith type. For example, the honeycomb body (1) having a heater function according to the present invention is generally manufactured as follows. That is, a flat-plate band material (11) made of a thin metal plate or a flat-plate sheet material (11 ') made of glass fiber or ceramics (hereinafter also referred to as a flat-plate band material or a flat-plate sheet material) and a thin-walled material. Corrugated strip material (12) made of metal plate, or corrugated sheet material (1 made of glass fiber or ceramics
2 ') (hereinafter also referred to as corrugated strip material or corrugated sheet material) is used in combination with one of which is made of a thin metal plate capable of conducting electricity. It is manufactured by stacking sheet materials so that they abut each other, and winding and stacking them in a spiral shape. By this winding molding, as shown in FIG. 2 which will be described later, a large number of mesh-like ventilation hole passages (cells) (13) which become passages for exhaust gas are automatically formed. In the present invention, the honeycomb body (1) is not limited to the above-mentioned wound type, but is a hierarchical type manufactured by stacking the materials of the above combination in a hierarchical manner so as to abut each other. May be. Further, as a modification of the winding type, a honeycomb body having a racetrack-shaped cross section may be formed by forming a large cavity in the center after the winding molding and crushing the cavity. Further, when viewed around a material in which the above-mentioned combination of materials are brought into contact with each other (hereinafter referred to as a purification element), the respective purification elements are radially arranged from the center point of the honeycomb body. It may be a body or an S-shaped honeycomb body having a structure in which each purification element is bent into a substantially S-shaped curve. In the present invention, as the flat plate-shaped strip, a strip that is used in the production of an ordinary metal monolith type catalyst-supporting base material, for example, chromium steel (chrome 13 to
25%), Fe-Cr 20% -Al 5%, etc. heat-resistant stainless steel, or heat-resistant stainless steel with rare earth added to improve oxidation resistance.
Use 0.1 mm strips. Further, as the corrugated plate material, the corrugated material obtained by corrugating the flat plate material so as to have a predetermined substantially sine wave or trapezoidal wave is used. In addition, considering the electrical conductivity of the honeycomb body at high temperature, a Ni-Cr alloy,
Ni-Cr-Fe alloy, Ni-Cr-Al-Fe alloy, etc. are also used.

Next, a strip material (a flat or corrugated sheet made of a thin metal plate) and a sheet material (glass) which constitute the honeycomb body (1) having the above-mentioned heater function, which is the greatest feature of the present invention. The combination of flat or corrugated fibers or ceramics) will be described in more detail. A feature of the present invention is that, in a combination of these strips and sheet materials, one of them is a flat metal strip (11) or a corrugated strip (12) made of a thin metal plate that can be energized. A honeycomb body is manufactured as an electrically insulating corrugated sheet material (12 ') or a flat sheet material (11'), and both band materials (11, 1
2) One or both of them are energized so that a large amount of heat is obtained by resistance heating. In the present invention, the term “electrically insulating property” is used not only to mean that it literally insulates electricity, but also to have a relatively lower electrical conductivity than both strips. On the other hand, when a flat metal strip (11) and a corrugated strip (12) made of thin metal plates that can be simply energized are stacked so as to abut each other to form a honeycomb body, electricity is The honeycomb body (1) is easily conducted through the abutting portions of the strips (11, 12) (specifically, the portions where the corrugated strips come into contact with the flat strips at the crests and troughs of the waves). ), The amount of heat generated by resistance heating is small. Therefore, in the present invention, both strips (11, 1
In order to make it difficult for electricity to flow when electricity is applied at the contact part of 2), a combination of the above-mentioned both band materials (11 or 12) and electrically insulating sheet material (11 'or 12') is adopted. is there. This state is shown in FIG.

FIG. 2 shows a state in which a corrugated strip material (12) made of a thin metal plate that can be energized and a flat sheet material (11 ') made of glass fiber are stacked so as to abut each other. Has been done. Then, when the band material (12) and the sheet material (11 ') are stacked so as to be in contact with each other to form the honeycomb body (1), as shown in the figure, the exhaust gas passage is automatically provided. Large number of cells (13)
Is formed. In the present invention, the relationship of the combination of the strip material and the sheet material is replaced with a combination of a flat metal strip material (11) made of an energizable thin metal plate and a corrugated sheet material (12 ') made of ceramics. It goes without saying that it is okay.
The glass fiber or ceramic flat sheet material (11 ') or corrugated sheet material used in the present invention
As (12 ′), glass fiber cemented with ceramic cement or ceramics such as alumina (Al ₂ O ₃ ) is used. In the present invention, the honeycomb body (1) having a heater function has a main catalyst supporting matrix (2) in order to improve the exhaust gas purifying ability of the exhaust gas purifying device.
A catalyst for purifying exhaust gas may be supported not only on the side of the honeycomb body (1) but also on the side of the honeycomb body (1). In that case, as both strip materials (11, 12) made of thin metal plates, whisker-like or mushroom-like alumina (Al ₂ O
₃ ) Those having a layer are preferable. As the other material, a flat plate-shaped sheet material or corrugated sheet material made of ceramics is preferable. These materials are preferable because they can firmly hold the exhaust gas purifying catalyst such as Pt, Rh, and Pd.

In FIG. 1, a honeycomb body (1) having a heater function is provided with lead wires (4) and (5) for energization,
In the case of purifying exhaust gas of a car, it is connected to a battery mounted on the car or a power supply unit (6) provided specially. In the present invention, a honeycomb body having a heater function
Power supply (energization) to (1) may be performed with a timer for a limited time, or the temperature of the honeycomb body (1) and the exhaust gas temperature can be measured with a sensor attached to a desired part of the honeycomb body (1). It may be turned on and off without any limitation. Honeycomb body having a heater function of the present invention (1)
With electricity, the large electric resistance of the honeycomb body (1) converts electric energy into heat, and the inside of the honeycomb body (1) can be heated to a high temperature suitable for catalytic reaction. Needless to say, the exhaust gas carried on the wall surface of the central part of the main catalyst-supporting matrix (2) and its vicinity at the time of cold start in view of the flow velocity distribution of the exhaust gas inside the main catalyst-supporting matrix (2). It is extremely important to maintain the activation temperature of the purification catalyst at optimal conditions (eg, around 500 ° C) faster than any other part. For that purpose, in the honeycomb body (1) having a heater function, which is arranged on the windward side of the main catalyst supporting base body (2), the current-carrying electrode is arranged in the central portion thereof, and the central portion of the honeycomb body (1) and its The exhaust gas flow passing through the vicinity may be heated more rapidly and higher than other parts.

In the present invention, the main catalyst supporting base (2) may be a ceramic monolith type.
Alternatively, it may be of a metal monolith type. These may be manufactured according to a conventional method, and a method of manufacturing a metal monolith type will be described below.

In the present invention, the main catalyst supporting base material (2) is manufactured by a conventional method, and its cross-sectional shape is not restricted in any way. For example, the metal monolith type carrier matrix (2) is manufactured in the following manner in the same manner as the honeycomb body (1) having the heater function. The main catalyst supporting base (2) shown in FIG. 3 having a circular cross-section has a heat-resistant thin metal plate flat plate strip (11) and corrugated strip strip (12) abutting against each other. It is made by stacking and stacking it in a spiral shape. A large number of mesh-like ventilation passages (cells) (13) which become exhaust gas passages are automatically formed by the winding lamination. More specifically,
It may be manufactured as follows. Fe-Cr 20% -Al
5% -Ce 0.02% heat-resisting steel with a thickness of 0.04 mm and a width of 38 mm is used to pass a flat strip of steel strip between the forming gears, and the pitch width (1.0 mm) and wave height (0.3 mm) are applied. Use a plate-shaped strip. Next, the flat plate-shaped strip and the corrugated strip-shaped strip are stacked on top of each other, and the ends thereof are inserted into the slits of the slit-formed roll forming rod, which are collectively wound and laminated, for example, in a large number in the axial direction. The main catalyst-supporting base material (2) made of metal and having an outer diameter of 70 mm and having a mesh-like ventilation hole path (cell density of 300 cpsi) may be used. Then, in order to form a catalyst supporting layer for supporting the catalyst on the main catalyst supporting base material (2), a slurry containing activated alumina (γ-Al ₂ O ₃ ) powder and alumina sol is applied, and this is applied at 600 ° C.
The heat treatment may be carried out to form the catalyst supporting layer. Further, in order to support a catalyst for purifying exhaust gas such as a three-way catalyst on the catalyst supporting layer, it may be supported by an ordinary method such as impregnation. The main catalyst-supporting base material (21) having a circular cross-section shown in FIG. 4 is formed so that the flat band material (11) and the corrugated plate material (12) made of a heat-resistant thin metal plate are in contact with each other. It is made by stacking layers. The main catalyst-supporting mother body (22) shown in FIG. 5 having a racetrack shape (oval shape) in cross section is a modification of the winding type shown in FIG. A cavity having a diameter is formed, and then the cavity is pressed to form a racetrack-shaped cross section. The main catalyst supporting base material (23) having a circular cross-sectional shape shown in FIG. 6 is a purification element (E) by abutting a heat-resistant thin-walled metal flat plate strip and corrugated strip.
The purification element (E) is produced by radially extending a desired number of the purification elements (E) from the fixed shaft (C) as a starting point. In order to make the honeycomb body (1) of a radial type of this kind, it is only necessary to adopt a combination of materials (strip material and sheet material) that form the honeycomb body (1). Figure 7
The main catalyst-supporting mother body (24) having a circular cross-sectional shape shown in (1) is a purification element (E) by bringing a heat-resistant thin metal plate flat plate-shaped strip and corrugated plate-shaped strip into contact with each other. (E) are stacked in layers so that the outermost surface is a flat strip, and each purification element (E) is centered around the two fixing points (C1, C2) set on the upper and lower outermost surfaces. It is manufactured by bending in the opposite direction, that is, by transforming each purification element (E) into a substantially S-shaped curve. In order to make the honeycomb body (1) of this type S-shaped type, it is only necessary to adopt a combination of materials (strip material and sheet material) that constitute the honeycomb body (1).

In the present invention, the metal case (3) is for accommodating and fixing the honeycomb body (1) having the heater function and the main catalyst supporting matrix (2) inside, and both ends are open. However, the shape is not subject to any restrictions. For example, a metal case having an elliptical cross section or a substantially triangular cross section may be used in order to fit the cross section shown in FIGS. 3 to 7 or the space under the vehicle body. As a material for the metal case, heat-resistant steel of the same type as the main catalyst-supporting base material may be used, or a material having high heat-corrosion resistance may be used. Further, it is possible to use a double structure in which the metal material of the outer portion is richer in heat resistance and corrosion resistance than the inner portion, specifically, ferritic stainless steel may be used for the inner portion and austenitic stainless steel for the outer portion.

[0016]

In the exhaust gas purifying apparatus of the present invention, since the honeycomb body having the heater function of generating a large amount of heat due to resistance heating is arranged on the windward side of the main catalyst supporting base body, there is a particular problem in exhaust gas treatment. Therefore, the exhaust gas purification capacity at cold start can be greatly improved. Also,
Since the honeycomb body itself serves as a heater, there is an advantage that it is not necessary to separately manufacture and dispose a heater material.

[Brief description of drawings]

FIG. 1 is an axial cross-sectional view of an exhaust gas purification device of the present invention.

[Fig. 2] Fig. 2 is a cross-sectional view of a corrugated plate material made of a thin metal plate and a glass fiber flat sheet material used for manufacturing a honeycomb body having a heater function of the present invention.

FIG. 3 is a cross-sectional view of a main catalyst-supporting base body of the first aspect, which is a main component of the exhaust gas purification device of the present invention.

FIG. 4 is a cross-sectional view of a main body carrying a main catalyst of a second aspect, which is a main constituent element of the exhaust gas purifying apparatus of the present invention.

FIG. 5 is a cross-sectional view of a main catalyst carrier of a third aspect, which is a main constituent element of the exhaust gas purification apparatus of the present invention.

FIG. 6 is a cross-sectional view of a main catalyst carrier according to a fourth aspect, which is a main component of the exhaust gas purification device of the present invention.

FIG. 7 is a cross-sectional view of a main catalyst-supporting base material according to a fifth aspect, which is a main component of the exhaust gas purification device of the present invention.

[Explanation of symbols]

 A: Exhaust gas purifying device F: Exhaust gas flow direction 1: Honeycomb body with heater function 11 ': Glass fiber flat sheet material 12: Wave of thin metal plate Plate-shaped strip material 2,21,22,23,24 …… Main catalyst supporting base 3 ………… Metal case 4,5 ………… Lead wire 6 ………… Battery

[Procedure amendment]

[Submission date] September 7, 1991

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (9)

[Claims] 1. An exhaust gas purifying apparatus for purifying exhaust gas, comprising a honeycomb body having a heater function on the windward side and a main catalyst supporting base on the leeward side with respect to the exhaust gas flow, and the heater. The honeycomb body having the function is (i) (a) a thin metal plate that can be energized or a corrugated plate material, and (b) a corrugated sheet material or a flat sheet material made of glass fiber or ceramics. It is manufactured by stacking materials so that they come into contact with each other, and (ii) the flat strip and / or the corrugated strip has electrode terminals for energization. Exhaust gas purification device characterized by. 2. The exhaust gas purifying apparatus according to claim 1, wherein a gap space (S) is provided between the honeycomb body having a heater function and the main catalyst supporting base body. 3. The exhaust gas purifying apparatus according to claim 1, wherein the honeycomb body having a heater function carries an exhaust gas purifying catalyst. 4. The exhaust gas purifying apparatus according to claim 1, wherein the main catalyst supporting base is a metal monolith type or a ceramic monolith type. 5. A honeycomb body having a heater function is (a)
Flat plate or corrugated strip made of thin metal plate and (b) corrugated sheet or flat sheet made of glass fiber or ceramic are stacked so that they abut each other, and they are rolled together. The exhaust gas purification device according to claim 1, wherein the exhaust gas purification device is manufactured by stacking layers once. 6. A honeycomb body having a heater function is (a)
Manufactured by stacking flat or corrugated strips made of thin metal plates and (b) corrugated sheet or flat sheet made of glass fiber or ceramics in a layered manner so that they abut each other. The exhaust gas purifying apparatus according to claim 1, which has been exhausted. 7. A honeycomb body having a heater function is (a)
A flat metal strip or corrugated metal strip made of a thin metal plate and (b) a corrugated sheet material or a flat metal sheet made of glass fiber or ceramics are brought into contact with each other to form a purification element, and the desired purification element The exhaust gas purifying apparatus according to claim 1, wherein a number of the honeycomb units are radially extended from a fixed axis as a starting point to form a radial honeycomb body. 8. A honeycomb body having a heater function is (a)
A flat metal strip or corrugated metal strip made of a thin metal plate and (b) a corrugated sheet material or flat metal sheet made of glass fiber or ceramics are brought into contact with each other to form a purification element. The layers are stacked in layers so that the outermost surface becomes a flat strip, and each purification element is bent in the opposite direction around two fixing points set on the upper and lower outermost surfaces to form an S-shaped honeycomb body. The exhaust gas purification device according to claim 1, which is a 9. A honeycomb body having a heater function and a main catalyst supporting matrix have a circular, racetrack-shaped cross-section,
Alternatively, the exhaust gas purification device according to claim 1, which is selected from an elliptical shape.