JPH03245851A - Metal support of catalytic converter and its preparation - Google Patents

Abstract

PURPOSE:To avoid large bending deformation in order to prevent an insulating ceramic layer from peeling off after the insulating ceramic layer is formed on the surface of a main metal substrate by inserting a wavy spacer into a gap made by folding the main metal substrate several times to form fine flowing routes dividually. CONSTITUTION:A flat or almost flat metal sheet strip 11 is so folded several times so as to keep a constant gap and be formed into a prescribed outer shape. The main metal sheet 11 formed into the prescribed outer shape is immersed in a ceramic coating liquid 21 to form an insulating ceramic layer 14. Then, a metal sheet 12 bent into an uneven wavy shape is cut into pieces with prescribed length. The resulting wavy spacers 12 of the wavy metal sheet are inserted into each gap 11 of the main metal sheet 11. The spacer 12-inserted assembled body is immersed into a ceramic coating liquid 23 to fix the main metal sheet and the wavy spaceres each other and obtain a desired catalytic converter.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a metal carrier for a catalytic converter for exhaust purification used in an internal combustion engine for an automobile, and more particularly to a metal carrier that itself serves as a heater, and a method for manufacturing the same.

BACKGROUND OF THE INVENTION In recent years, as catalytic converters for purifying exhaust gas in internal combustion engines for automobiles, there has been a tendency to use metal carriers which are advantageous in terms of heat capacity and pressure loss.

On the other hand, as is well known, a catalytic converter cannot perform a sufficient catalytic action unless it is heated to a predetermined activation temperature. However, it takes a certain amount of time for the exhaust purification performance to reach a sufficient level.

Therefore, it has been conventionally thought to heat the catalyst carrier using an electric heater. In particular, since the metal carrier mentioned above is itself composed of a conductive metal plate, the metal plate itself can be used as a resistor or A method of using it as a heater has been proposed.

The problem here is that the resistivity of stainless steel metal plates, which are generally used for metal carriers from the point of view of heat resistance, etc., is very low. This means that when electricity is applied in the direction or length direction, the resistance value required as a heating element cannot be secured at all.

Considering these points, conventionally, Japanese Patent Application Laid-Open No. 4854312
The publication discloses that the surfaces of a flat first metal plate and a second metal plate bent into an uneven waveform are coated with an insulating ceramic layer in advance, and then the two are overlapped and wound. A cylindrically shaped metal carrier is shown.

In this device, the first metal plate and the second metal plate forming a spiral shape are insulated from each other over their entire length. By energizing it as a terminal, it is possible to secure a fairly large length as a resistor.

Problems to be Solved by the Invention However, in the above-mentioned conventional configuration, the first layer is coated with an insulating ceramic layer on the surface. After coating, the second metal plate must be curved and wound to form a substantially cylindrical shape, so in reality, a large amount of the insulating ceramic layer peels off during the winding process, making it impossible to put it into practical use. cannot be provided. Furthermore, peeling of the insulating ceramic layer tends to cause a short circuit within the carrier, that is, a decrease in resistance value.

Means for Solving the Problems The metal carrier of the catalytic converter according to the present invention is made by folding a strip-shaped metal plate multiple times so as to maintain a predetermined gap, and the starting point and the ending point of the metal carrier are made of a main metal that becomes a terminal part. board and
It consists of an insulating layer coated on the entire surface of the main metal plate, and a metal plate bent and formed into an uneven corrugated shape. It is characterized by comprising a plurality of wave-shaped spacers that define a flow path between the spacer and the plate.

Furthermore, the method for manufacturing the metal carrier according to the present invention includes:
A process of forming a flat or nearly flat belt-shaped metal plate into a predetermined shape by folding it multiple times to maintain a constant gap, and then immersing the main metal plate with the predetermined shape in a ceramic coating liquid to form an insulating ceramic. a step of forming a layer, a step of cutting each metal plate bent into an uneven corrugated shape to a predetermined length dimension, and a step of inserting a corrugated spacer made of this corrugated metal plate into each gap of the main metal plate. and a step of fixing the main metal plate and the corrugated spacer to each other by immersing the assembly into which the corrugated spacer is inserted in a ceramic coating liquid.

Function: In the above configuration, the main metal plate is previously folded and formed into a predetermined outer shape, and the entire surface thereof is coated with an insulating ceramic layer. A corrugated spacer is inserted into each gap to define a fine flow path, and each corrugated spacer and the main metal plate are insulated by the insulating ceramic layer. In other words, the length of the resistor can be ensured to be equal to the total length of the main metal plate, and the resistance value can be sufficiently large. Furthermore, since the ceramic layer is not subjected to strong bending deformation after coating, peeling of the ceramic layer is prevented.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

2 and 3 show the overall structure of a catalytic converter for an internal combustion engine equipped with a metal carrier l according to the present invention.

The metal carrier I has a substantially cylindrical shape with an elliptical cross section, and is housed inside a metal casing 2. The casing 2 has an exhaust port 3 at one end and an exhaust outlet 4 at the other end, each having a flange 3 for connecting an exhaust pipe.
A, 4a are provided. In addition, casing 2 is
The carrier 1 is preliminarily formed into two parts along the longitudinal direction, and is integrated by accommodating the carrier 1 and welding the flanges 2a on both side edges to each other.

The carrier I is held by a pair of annular bulges 2b in the middle of the casing 2 and annular caps 5 welded to both the front and rear sides of the casing 2, but this catalytic converter uses the carrier 1 itself as a heater. Then, since it is necessary to reliably insulate between the carrier l and the casing 2, the bulge part 2b and the cap 5 in contact with the carrier l are
An alumina layer 6 is formed on the inner circumferential surface of each to have an appropriate thickness.

Then, as shown in FIG. 3, a minus side electrode 7 and a plus side electrode 8 are placed so as to sandwich the carrier l from the short axis direction of the ellipse.
is provided. These electrodes 7.8 are each inserted into a mounting hole in the casing 2 via an insulating bush 9.

Next, the metal carrier 1 will be described in detail with reference to FIG. This metal carrier 1 is roughly composed of a main metal plate 11 consisting of two continuous strip-shaped metal plates, and a plurality of corrugated spacers 12 that are combined with this main metal plate 11 to form a large number of minute flow channels. It is configured.

The main metal plate 11 is basically a flat band-shaped metal plate.
A certain gap, for example, a gap 13 with a width W of about 1 to 311W.
The material is alternately folded back a plurality of times so as to maintain the same shape, and the overall shape is formed to have a substantially cylindrical outer shape with an elliptical cross section as described above (see FIG. 4). The main metal plate 11 is individually coated, and an insulating ceramic layer 14 is formed over its entire surface.

The corrugated spacer 12 is made of a metal plate bent into an uneven corrugated shape with a height approximately equal to the width W of the gap I3 minus the thickness of the insulating ceramic layer 14. They are each cut into a combined length L (see FIG. 5), and are also individually coated to form an insulating ceramic layer 15 over their entire surface. Incidentally, this coating treatment before assembling the wave-shaped spacer 12 is not necessarily necessary and can be omitted.

The above insulating ceramic layer 14.15 may include alumina, zirconia, a mixture of alumina and lanthanum oxide,
Alternatively, a mixture of alumina and cerium oxide can be used. In addition, the main metal plate If and the corrugated spacer 1
As the base material 2, a thin stainless steel metal plate, for example, a material containing mainly Fe, Cr2O%, A45%, and a trace amount of La is used. Note that the resistivity of this material is approximately 150 μΩ·ci.

The wave-shaped spacers 12 are each inserted into the gap 13 of the main metal plate ll, and the combination of the two defines a fine flow path 16, as shown in FIG. Further, in the state in which the two are combined, the entire body is further coated with a laminated layer 17 of alumina or the like, thereby fixing and holding the two together. In the illustrated example, a catalyst metal is included in the ceramic layer 17 at this stage, and it also serves as a catalyst layer. Coating is also possible.

Main metal plate 1 of metal carrier 1 configured as described above
1 is a starting point 11a and an ending point 11b (
(see FIG. 4) serve as terminal portions, which are electrically connected to electrodes 7 and 8, respectively, as shown in FIG.

Therefore, according to the above configuration, the main metal plate 11 and the corrugated spacer 12 are reliably insulated by the insulating ceramic layers 14, 15, so that the main metal plate 11 will not be short-circuited at the intermediate portion. In other words, the entire length of the main metal plate ll can be used as a resistor, which is necessary for the heater.
It becomes possible to secure a resistance value of about 5Ω.

FIG. 6 is a process explanatory drawing showing the method for manufacturing the metal carrier I, and the manufacturing method will be explained below based on this.

First, as described above, the flat band-shaped metal plate is alternately folded a plurality of times to form the main metal plate 11 having a substantially cylindrical outer shape with an elliptical cross section (step a).

In parallel with this, a metal plate bent and formed into an uneven corrugated shape is cut into a predetermined length to prepare the necessary corrugated spacer 12 (step b).

Then, the main metal plate II is placed in a ceramic coating liquid 21 made of an insulating ceramic such as alumina.
is immersed and dried to form an insulating ceramic layer 14 on the surface (Step C).

Similarly, metal plates of a predetermined length that will become the corrugated spacers 12 are individually immersed in the ceramic coating liquid 21,
Then, it is dried to form an insulating ceramic layer 15 on the surface (step d). As described above, the formation of the insulating ceramic layer 15 on the side of the corrugated spacer 12 can be omitted.

Next, each corrugated spacer 12 is inserted into each gap 13 of the main metal plate 11 (step e). At this time, the main metal plate 11 can be expanded and deformed to some extent in the direction in which the gap 13 widens, so that the main metal plate 11 can be easily inserted without peeling of the insulating ceramic layers 14 and 15.

Then, in this state, it is temporarily fixed using a suitable jig or the like, and the entire assembly 22 is immersed in a ceramic coating liquid 23 such as alumina, and then dried. As a result, the main metal plate 11 and each corrugated spacer 12 are firmly integrated (step f). As described above, by containing a catalyst metal in the ceramic coating liquid 23 at this time, it can serve as a catalyst layer.

In the above embodiment, the main metal plate is a flat metal plate!
(2) However, it is also possible to use a metal plate having a waveform that is sufficiently gentler than the waveform spacer 12, that is, a waveform that is close to flat.

Next, FIG. 7 shows an example of a metal carrier I assembled without forming the insulating ceramic layer 15 on the corrugated spacer 12 side as described above.

In the embodiments shown in FIGS. 8 and 9, the structure for holding the metal carrier 1 in the casing 2 has been changed, and an insulating ceramic fiber mat 25 is interposed to cover the entire circumference of the metal carrier 1. has been done. Note that an insulating alumina layer 6 is also provided on the inner periphery of the front and rear caps 5.

Furthermore, in the embodiment shown in FIGS. 1O and 11, a cylindrical ceramic inner case 26 is fitted around the outer periphery of the metal carrier 1, and is held within the bracket casing 2 via a ceramic fiber mat 27. This is what I did.

Effects of the Invention As is clear from the above explanation, according to the present invention, the entire length of one continuous metal plate serving as the main metal plate can be used as a resistor, so that the resistance value necessary for the heater can be easily secured. , and sufficient calorific value can be obtained. In particular, since we inserted corrugated spacers into the gaps between the main metal plates that were folded multiple times to define fine flow paths, the main metal plates would be subject to large bending deformations after being coated with an insulating ceramic layer on their surface. This prevents the insulating ceramic layer from peeling off, and prevents the resistance value from decreasing or varying due to short circuits.

[Brief explanation of drawings]

Fig. 1 is an enlarged cross-sectional view showing the main parts of the metal carrier according to the present invention, Fig. 2 is a cross-sectional view of a catalytic converter using this metal carrier, and Fig. 3 is a cross-sectional view taken along the line ■■ in Fig. 2. Figure 4 is an explanatory diagram showing the outline of the main metal plate, Figure 5 is an explanatory diagram showing the outline of the corrugated spacer, and Figure 6 is a process explanation showing one embodiment of the method for manufacturing a metal carrier according to the present invention. 7 is an enlarged sectional view of an embodiment in which the insulating ceramic layer of the wave-shaped spacer is omitted, FIG. 8 is a sectional view showing another embodiment of the catalytic converter, and FIG. 9 is a sectional view taken along the TI-rX line. FIG. 10 is a cross-sectional view showing still another embodiment of the catalytic converter, and FIG. 11 is a cross-sectional view taken along the line -M. ■Metal carrier, 11-main metal plate, 12-corrugated spacer, 14-insulating ceramic layer, 15-insulating ceramic layer, 7-ceramic layer. - 1 2 14, 15 7- 1-7, Fumisofuku layer (C) 11 (f)

Claims (2)

[Claims] (1) A main metal plate made by folding a belt-shaped metal plate multiple times to maintain a predetermined gap, and whose starting and ending points become terminals, and an insulator coated over the entire surface of this main metal plate. and a plurality of metal plates each formed of a metal plate formed into a concave and convex corrugated combination and each inserted into each gap of the main metal plate covered with the insulating layer to define a flow path between the main metal plate and the main metal plate. A metal carrier for a catalytic converter, characterized in that it is equipped with a sheet of corrugated spacers. (2) The process of forming a flat or nearly flat belt-shaped metal plate into a predetermined shape by folding it multiple times to maintain a constant gap, and immersing the main metal plate with the predetermined shape in a ceramic coating liquid. A step of forming an insulating ceramic layer, a step of cutting a metal plate bent and formed into an uneven corrugated shape into predetermined length dimensions, and a corrugated spacer made of the corrugated metal plate is placed in each gap of the main metal plate. Manufacturing a metal carrier for a catalytic converter, comprising the steps of: inserting the corrugated spacer; and immersing the assembly into which the corrugated spacer is inserted in a ceramic coating liquid to fix the main metal plate and the corrugated spacer to each other. Method.