JPH09220480A - Composite carrier for automobile exhaust gas purification - Google Patents

Abstract

(57) An object of the present invention is to form a composite body in which a metal honeycomb body and a ceramic honeycomb body are integrally polymerized in a casing, thereby making the best use of the advantages of each honeycomb body to purify exhaust gas. Provided is a composite carrier for improving automobile exhaust gas. A metal honeycomb body is fitted into a hollow portion of a ceramic honeycomb body formed into a hollow cylinder, and
The gap between the metal honeycomb body and the ceramic honeycomb body is filled with a non-heated expandable elastic sealing material to form a composite, the composite honeycomb body is loaded into the casing, and the gap between the casing and the ceramic honeycomb body is heated and expandable. It is characterized by being filled with. The ceramic honeycomb body may be fitted into the hollow portion of the metal honeycomb body formed in a hollow cylindrical shape via a heat-expandable elastic sealant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst-supporting metal carrier for purifying automobile exhaust gas, and more particularly to a metal carrier having a low heat capacity and high reactivity at the initial stage when the engine is started.

[0002]

2. Description of the Related Art As a catalyst carrier installed in an exhaust system for purifying exhaust gas of an automobile, a honeycomb body carrying a catalyst is gradually made of metal instead of ceramic.

The ceramic honeycomb body is mainly composed of cordierite, has a high heat resistance and a low coefficient of thermal expansion, but has a mechanical strength of at most 40 kgf / mm ² and is vulnerable to an impact, and therefore a cell through which exhaust gas passes. The thickness of the honeycomb wall that forms the cells is as thick as 170 μm, and therefore the heat retention is excellent, but since the cell opening ratio is only 70%, the pressure loss with respect to the exhaust gas is large, and the heat generated when the engine is started. In contact with exhaust gas of low energy, it takes time to reach the catalyst activation temperature.

On the other hand, the metal honeycomb body is formed by superposing and winding a flat foil and a corrugated foil, which is made of ferritic stainless steel containing Al and has a thickness of almost the same. Those having a thickness of 50 μm or less are used. That is, compared with the wall thickness of the conventional ceramic honeycomb body, 1 /
Since the thickness is 3 or less, the cell opening ratio is large and thus the pressure loss can be small, and the heat capacity can be small, so that rapid heating is possible, which is advantageous for activation of the catalyst, but it is advantageous for foil rolling, processing and Joining is difficult and the manufacturing cost is not low. The coefficient of thermal expansion is also large.

As described above, both have advantages and disadvantages, and the use of each of them has been studied. For example, one exhaust system has a high temperature part, that is, there is an example in which a metal carrier is used immediately below the manifold, and a ceramic carrier is used on the underfloor side, but although the effect for each carrier is achieved,
No special effect of the combination is seen.

Japanese Unexamined Patent Publication No. 4-341348 discloses a structure shown in FIG.
As shown in, a carrier for arranging the ceramic honeycomb body 8 on the outer periphery of the metal honeycomb body 7 has been proposed for the purpose of improving purification performance. However, since the respective honeycomb bodies have different thermal expansion characteristics, the thermal expansion Ceramic honeycomb body 8
The portion of the metal honeycomb body 7 that is in contact with is buckled, and a gap is created between the honeycomb bodies 7 and 8 during repeated use, which may cause rattling due to vibration or cracking of the ceramic honeycomb body 8 due to impact. is there. In addition, the purification performance also decreases due to the gaps between the honeycomb bodies. In the figure, 9 is an outer cylinder.

On the other hand, in Japanese Unexamined Patent Publication No. 6-241037, a double-structured honeycomb body 12 having a ceramic honeycomb body 8 inside and a metal honeycomb body 7 arranged outside as shown in FIG. 8 has been proposed for the purpose of protecting the honeycomb body 8 from external impact, but since the thermal expansion coefficient of the metal honeycomb body 7 is larger than that of the ceramic honeycomb body 8, a gap is formed between the honeycomb bodies during repeated use, which causes rattling due to vibration. Or, a shock may cause cracking.

[0008]

DISCLOSURE OF THE INVENTION The present invention is to solve the above-mentioned problems, and a metal honeycomb body and a ceramic honeycomb body are formed into a composite body having an integral polymerized structure in a casing. It is an object of the present invention to provide a composite carrier for purifying exhaust gas of automobiles, which improves the exhaust gas purification efficiency by making the most of the advantages of each honeycomb body.

[0009]

In order to achieve the above object, the present invention has the following structures. That is, (1) a flat foil made of a heat-resistant metal foil and a corrugated foil are superposed and wound, and a spirally formed metal honeycomb body is fitted into the hollow portion of a cylindrical ceramic honeycomb body having a hollow portion. At the same time, the gap between the metal honeycomb body and the ceramic honeycomb body is filled with a non-heat-expandable elastic sealing material to form a composite, and the composite honeycomb body is loaded into the casing, and the gap between the casing and the ceramic honeycomb body is expanded by heating. A composite carrier for purifying automobile exhaust gas, characterized by being filled with a sealing material. And (2) the ceramic honeycomb body, a flat foil made of a heat-resistant metal foil and a corrugated foil are overlapped and spirally wound, and fitted into the hollow portion of the metal honeycomb body formed into a hollow cylinder, and the ceramic The gap between the honeycomb body and the metal honeycomb body is filled with a heat-expandable elastic sealing material to form a composite, the composite honeycomb body is loaded into the casing, and the gap between the casing and the metal honeycomb body is not heated and expandable. A composite carrier for purifying automobile exhaust gas, characterized by being filled with a material.

As described above, the filled non-heat-expandable elastic seal holding material is in contact with the outer periphery of the honeycomb body, and does not expand rapidly even when heated by the exhaust gas. It does not compress, and the expansion and contraction of the metal honeycomb body can be buffered and absorbed, so that the metal honeycomb body does not suffer pressure loss or damage. Although the ceramic honeycomb body has a low thermal expansion property, the casing and the metal honeycomb body have a large thermal expansion coefficient, so that a gap can be formed by repeated use, by filling with a heat-expandable elastic sheet holding material. You can

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings. 1 (a) and 1 (b) are sectional views showing an example of the composite carrier of the present invention, 1 is a metal honeycomb body, 2 is a ceramic honeycomb body, 3 is a casing, and 4 is a metal honeycomb body 1 and a ceramic honeycomb body. The non-heat-expandable elastic seal material filled in the gap between the body 2 and 5 is the heat-expandable elastic seal material filled in the gap between the ceramic honeycomb body 2 and the casing 3.

The metal honeycomb body 1 is formed by stacking a heat-resistant steel flat foil 11 and a corrugated foil 12 and spirally winding them, and the contact portion between the flat foil 11 and the corrugated foil 12 is brazed or heat-diffused. It is joined by means. On the other hand, as described above, the ceramic honeycomb body 2 is a cylindrical body (a donut-shaped cross section in the radial direction) having a tubular hollow portion 2a made of cordierite, and the hollow portion has a diameter of the hollow portion 2a. Insert the metal honeycomb body 1 having a slightly smaller outer diameter,
A non-heat-expandable elastic sealing material 4 made of, for example, ceramic fibers such as alumina, mullite fibers, or the like, which does not rapidly expand at a certain temperature in a gap formed between both honeycomb bodies.
To support the metal honeycomb body. The coefficient of thermal expansion is about (1-9) × 10 ^-6 . As a filling method of the sealing material 4, for example, the outer periphery of the metal honeycomb body 1 is covered with a non-heated and expandable elastic sealing material 4 in a mat shape, and the hollow portion of the ceramic honeycomb body 2 is press-fitted together with the metal honeycomb body 1. There is. A gap is also formed between the casing 3 and the ceramic honeycomb body 2, and the gap is 400 ° C., for example, of an interram mat (trade name) containing leucite.
Although the heat-expandable elastic sealing material 5 that rapidly expands in heat is filled as described above, the filling means may be the same as described above.

By thus combining the two honeycomb bodies to form the catalyst carrier, the ceramic honeycomb body has a high heat retaining property, while the metal honeycomb body has a small heat capacity and a high heating rate, so that the catalyst during the initial operation of the engine is A metal honeycomb body capable of rapid heating is advantageous for early activation of the honeycomb body, and when the honeycomb body is cooled such as when the engine is stopped or the engine is temporarily stopped, the heat retention of the ceramic honeycomb body prevents the metal honeycomb body from cooling. It suppresses and improves the thermal efficiency at the time of starting.

When the metal honeycomb body 1 is fitted in the hollow portion 2a of the ceramic honeycomb body 2, the gap between the metal honeycomb body and the ceramic honeycomb body is filled with the non-heat-expandable elastic sealing material 4 when heating. The body expands due to thermal expansion and increases in diameter, while the ceramic honeycomb body 2
Has a thermal expansion coefficient of about 1/10 that of a metal honeycomb body and a small expansion margin, so if a non-heat-expandable elastic sealing material is not used, a large compressive force will act on the ceramic honeycomb inner peripheral surface and the metal honeycomb outer peripheral surface. However, this is to prevent the metal honeycomb body having low high temperature strength from buckling.

When buckling, which is a plastic deformation, occurs, the outer diameter becomes smaller than the initial outer diameter by the amount of buckling after cooling,
Since the space between the ceramic honeycomb body and the metal honeycomb body expands, there is a gap, and exhaust gas leaks and the metal honeycomb body is displaced due to a reduction in the holding force between the honeycomb bodies.
In this case, the non-heat-expandable sealing material is effective in absorbing the expansion / contraction of the metal honeycomb body generated during heating / cooling and maintaining a strong support.

On the other hand, the use of the heat-expandable elastic seal 5 for filling the gap between the metal casing 3 and the ceramic honeycomb body 2 causes the seal material to expand in association with heating when the metal casing 3 thermally expands. However, it is possible to eliminate the difference in the coefficient of thermal expansion between the metal and the ceramic honeycomb, and prevent the formation of voids between the metal casing 3 and the ceramic honeycomb body 2.

2 (a) and 2 (b) show another embodiment of the present invention, in which the honeycomb body is arranged on the opposite side of FIG. That is, the metal honeycomb body 10 has a cylindrical shape (a donut-shaped cross section in the radial direction) having a hollow portion 10a in the central portion.
By filling and interposing the heat-expandable elastic sealing material 5 in the hollow portion 10a of the honeycomb body 10, a cylindrical ceramic honeycomb body 20 having a diameter slightly smaller than the hollow portion is loaded and supported.

When the ceramic honeycomb body 20 is fitted into the hollow portion 10a of the metal honeycomb body 10, the gap between the outer peripheral surface of the ceramic honeycomb body 20 and the inner peripheral surface of the metal honeycomb body 10 is increased during heating, while the metal The gap between the outer peripheral surface of the honeycomb body 10 and the metal casing 3 becomes smaller. Therefore, in this case, the heat-expandable elastic seal material 5 is used between the outer peripheral surface of the ceramic honeycomb body 20 and the inner peripheral surface of the metal honeycomb body 10, and the non-heat-expandable elastic seal material is used between the metal casing 3 and the metal honeycomb body 10. Material 4
Is effective in preventing the formation of gaps,
It has the same effect as that of FIG.

FIG. 3 is a modification of FIG. 1, in which the short metal honeycomb body 100 is fitted into the hollow concave fitting portion 201 provided on the front surface side of the ceramic honeycomb body 200 to form the metal honeycomb body 100 and the ceramic honeycomb body 200. The non-heated expandable elastic sealing material 4 is filled in the gap. The gap between the casing 3 and the ceramic honeycomb body 200 is filled with the heat-expandable elastic sealing material 5 as in FIG. The metal honeycomb body and the ceramic honeycomb body may have a structure in which their positions are interchanged together with the elastic sealing material. Reference numeral 6 in the figure denotes a cone portion of the casing.

The metal honeycomb body and the ceramic honeycomb body combined in FIGS. 2 and 3 have the same functions as in FIG. 1, and play a sufficient role in activating the catalyst. Further, each elastic sealing material fills the gap to support and protect each honeycomb body and improve durability.

[0021]

【Example】

[Embodiment 1] An embodiment of FIG. 1 will be described. 20Cr
Plate thickness of 50μm made of 5Al ferritic stainless steel
The flat foil and the corrugated corrugated foil were laminated and wound to form a metal honeycomb body 1 having an outer diameter of 45 mm and a length of 90 mm. The contacts of the flat foil and the corrugated foil of this metal honeycomb body were brazed and joined. Also, the wall thickness is 17 by extrusion molding.
A circular ceramic honeycomb body 2 made of cordierite having a diameter of 0 μm, an outer diameter of 90 mm and a length of 90 mm was manufactured, and a hole having a diameter of 53 mm was made at the center with a drill cutter to form a hollow portion 2a. As the non-heat-expandable sealing material 4, a sealing material made of high-purity alumina fiber having a thickness of 5 mm was wound around the outer periphery of the metal honeycomb body 1, and this was press-fitted into the hollow ceramic honeycomb body 2 and fitted therein. The casing 3 is made of a stainless steel material having a thickness of 1.5 mm and has an outer diameter of 100 mm and a length of 90 mm. A heat-expandable seal material (trade name: Interram Mat) 5 having a thickness of 4.9 mm was wound around the outer periphery of the ceramic honeycomb body 2 into which the metal honeycomb body 1 was fitted, and this was press-fitted and held in the casing 3.

[Embodiment 2] Next, the embodiment of FIG. 2 will be described. Using a flat foil of 20Cr5Al ferritic stainless steel with a plate thickness of 50 μm and corrugated corrugated foil, a flat foil is wound around a pipe with an outer diameter of 53 mm and fixed between the flat foils by spot welding. To form a flat foil ring, and then wrap the corrugated foil on the flat foil and wind it to an outer diameter of 45
A metal honeycomb body 10 with a mm inner core pipe was formed. After that, the inner core pipe was pulled out to form a hollow metal honeycomb body, and the flat foil and the corrugated foil were joined by brazing. The length was 90 mm as in Example 1. Then, by extrusion molding, a circular ceramic honeycomb body 20 made of cordierite having a wall thickness of 170 μm, an outer diameter of 45 mm and a length of 90 mm was manufactured. The heat-expandable sealing material 5 having the same thickness as that of the first embodiment, 4.9 mm,
Was wound and pressed into the hollow portion 10a of the metal honeycomb body 10. The casing 3 is made of stainless steel with a thickness of 1.5 mm.
The outer diameter is 100 mm, the length is 90 mm, and the same thickness as in Example 1 is 5
The non-heated expandable sealing material 4 made of high-purity alumina fiber of mm was wound around the outer periphery of the metal honeycomb body 10 in which the ceramic honeycomb body 20 was fitted, and was press-fitted and held in the casing.

[Embodiment 3] Next, the embodiment of FIG. 3 will be described. A flat foil of 20 Cr5 Al type ferritic stainless steel having a plate thickness of 50 μm and a corrugated corrugated foil of the flat foil are overlapped and wound to form a metal honeycomb body 100.
Was formed. The contacts of the flat foil and the corrugated foil of this metal honeycomb body were brazed and joined together to form a cylindrical body having an outer diameter of 45 mm and a length of 45 mm. A circular ceramic honeycomb body 200 made of cordierite having a wall thickness of 170 μm and an outer diameter of 90 mm is manufactured by extrusion molding, and a diameter of 53 mm is formed in the central portion thereof using a drill cutter.
A ceramic honeycomb body having local holes 201 having a depth of 45 mm was formed. As in Example 1, the non-heat-expandable sealing material 4 having a thickness of 5 mm was wound around the outer periphery of the metal honeycomb body 100 and press-fitted into the hole 201 of the ceramic honeycomb body 200 to be fitted therein. The casing 3 is made of stainless steel with a thickness of 1.5 mm.
The outer diameter is 100 mm and the length is 90 mm, and the thickness is 4.9 mm on the outer periphery of the ceramic honeycomb body fitted with the metal honeycomb body.
Wrap the heat-expandable sealing material 5 of the
Pressed and held inside.

[Comparative Example 1] A comparative example shown in FIG. 6 will be described. The thickness of the conventional honeycomb body shown in FIG.
A 9 mm heat-expandable sealing material 5 was wrapped and press-fitted into a casing 3 having an outer diameter of 100 mm and a length of 90 mm made of stainless steel having a thickness of 1.5 mm. The honeycomb body was manufactured by the same method as in Example 2. That is, the outer diameter of the ceramic honeycomb body 8 is 4
5 mm, the hollow portion 7a of the metal honeycomb body 7 is 45 mm,
The ceramic honeycomb body 8 was inserted into the hollow portion 7a of the metal honeycomb body 7 with an outer diameter of 90 mm.

Comparative Example 2 Next, a comparative example shown in FIG. 7 will be described. The same metal honeycomb body 1, ceramic honeycomb body 2, and casing 3 as in Example 1 were used, and a heat-expandable seal material 5 having a thickness of 4.9 mm was used as a seal material between the metal honeycomb body 1 and the ceramic honeycomb body 2. The sealing material between the honeycomb body 2 and the casing 3 has a thickness of 5
A metal carrier was produced using a non-heated expandable sealing material 4 made of mm high-purity alumina fiber.

Comparative Example 3 Next, a comparative example shown in FIG. 8 will be described. Using the same metal honeycomb body 10, ceramic honeycomb body 20, and casing 3 as in Example 2, a non-heat-expandable sealing material made of high-purity alumina fiber having a thickness of 5 mm is used as a sealing material between the metal honeycomb body 10 and the ceramic honeycomb body 20. 4, and a heat-expandable sealing material 5 having a thickness of 4.9 mm was used as a sealing material between the metal honeycomb body 10 and the casing 3 to produce a metal carrier.

The durability of each of the above-mentioned carriers was evaluated by a cold heat durability repeating test. The test conditions were as follows: each metal carrier was connected to the exhaust system of a 2000 cc gasoline engine, the gas temperature at the carrier inlet was set to 800 ° C., heated for 5 minutes, and then cooled to room temperature for 1000 cycles. The results are shown in Table 1, and it is clear that the carrier of the present invention has extremely excellent durability at high temperatures.

[0028]

[Table 1]

[0029]

As described above, according to the present invention, by combining the metal honeycomb body and the ceramic honeycomb body in a composite arrangement, the advantages of the respective honeycomb bodies are utilized to improve the exhaust gas purification efficiency. A carrier could be obtained.

[Brief description of drawings]

FIG. 1 is an example of a composite carrier of the present invention, in which (a) is a radial cross section and (b) is an axial cross section explanatory view.

FIG. 2 shows another example of the composite carrier of the present invention, (a) is a radial cross section, and (b) is an axial cross sectional explanatory view.

FIG. 3 is an explanatory cross-sectional view showing another example of the composite carrier of the present invention.

FIG. 4 is a sectional explanatory view showing a conventional example.

FIG. 5 is a perspective view showing a conventional double-structured honeycomb body.

FIG. 6 is a perspective view showing a composite carrier using a conventional honeycomb structure having a double structure.

FIG. 7 is a perspective view showing a carrier tested as a comparative example.

FIG. 8 is a perspective view showing a carrier of another example tested as a comparative example.

[Explanation of symbols]

 1,10,100: Metal honeycomb body 10a: Hollow part 2,20,200: Ceramic honeycomb body 2a: Hollow part 201: Hollow recessed fitting part 3: Casing 4: Non-heat-expandable seal material 5: Heat-expandable seal material 6: Cone part 7: Metal honeycomb body 7a: Hollow part 8: Ceramic honeycomb body 9: Ceramic carrier 11: Flat foil 12: Corrugated foil

Claims (2)

[Claims] 1. A flat metal foil made of heat-resistant metal foil and a corrugated foil are superposed and wound, and a spirally formed metal honeycomb body is fitted into a hollow portion of a cylindrical ceramic honeycomb body having a hollow portion. At the same time, the gap between the metal honeycomb body and the ceramic honeycomb body is filled with a non-heat-expandable elastic sealing material to form a composite, the composite honeycomb body is loaded into the casing, and the gap between the casing and the ceramic honeycomb body is expanded by heating. A composite carrier for purifying automobile exhaust gas, which is characterized by being filled with a porous sealing material. 2. A ceramic honeycomb body, a flat foil made of a heat-resistant metal foil, and a corrugated foil, which are superposed on each other and spirally wound, and fitted into a hollow portion of a cylindrical metal honeycomb body having a hollow portion. , A gap between the ceramic honeycomb body and the metal honeycomb body is filled with a heat-expandable elastic sealing material to form a composite, the composite honeycomb body is loaded into the casing, and the gap between the casing and the metal honeycomb body is not heated and expandable. A composite carrier for purifying automobile exhaust gas, characterized by being filled with an elastic sealing material.