JPH10131744A - Ceramic catalyst carrier supporting method and exhaust device with ceramic catalyst carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To arrange a ceramic catalyst carrier on a desired position by interposing a protect mat formed serving an alumina as a main component between the catalyst carrier and a supporting member for supporting the catalyst carrier to a housing in a condition to be compressed, and holding the catalyst carrier. SOLUTION: A carrier holding metal cylinder 3 whose one end is opened is mounted on a catalyst carrier 1 formed in such a constitution that a ceramic material is formed in a honeycomb shape and a catalytic metal is carried on its outer peripheral surface 1a. A protect mat 5 is interposed between the inner surface 3c of the metal cylinder 3 and the outer peripheral surface 1a, and a retainer 7 is mounted on end part of a side opposite to the bottom plate 3a of the metal cylinder 3. The protect mat 5 is formed in a flocculent shape serving an alumina as a main component so as to shorten the inner diameter thereof smaller than the outer diameter R of the catalyst carrier 1. After the protect mat 5 is mounted on the metal cylinder 3, the catalyst carrier 1 is pressed in so as to push-enlarge the protect mat 5, and thereby, the catalyst carrier 1 is held to the metal cylinder 3 in a condition in which the protect mat 5 is compressed sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for supporting a ceramic catalyst carrier supporting a catalyst and an exhaust device provided with the ceramic catalyst carrier.

[0002]

2. Description of the Related Art Conventionally, a catalyst has been provided in an exhaust system for purifying exhaust gas from an engine. As shown in FIG. 11A, the catalyst is provided by directly supporting the catalyst 42 on the inner wall 40 a of the exhaust pipe 40. A method in which the catalyst carrier 44 supporting the catalyst is supported by the expansion chamber partition wall 50 of the muffler device 48 as shown in FIG. The catalyst carrier 44 is configured by supporting a catalyst metal on a honeycomb-shaped laminate having a large number of mesh-shaped ventilation passages through which exhaust gas can pass, and storing the catalyst metal in a cylindrical metal case having both ends opened. , And is supported by the support member 46 and the expansion chamber partition wall 50 via the metal case. Further, as a material of the catalyst carrier, a ceramic which easily supports a catalyst metal such as platinum or rhodium, has high heat resistance, and is free from corrosion due to oxidation, such as metal, is often used.

[0003]

However, in the above-described method of directly supporting the catalyst on the inner wall 40a of the exhaust pipe 40, since the catalyst can be disposed near the engine, the temperature of the exhaust gas is high and the efficiency of the oxidation reaction of the catalytic metal is high. However, as is clear from FIG. 11 (a), there is a problem that the efficiency with which the exhaust gas contacts the catalyst is very poor, and as a result, the purification efficiency does not increase. In the method of supporting the catalyst carrier 44 in the exhaust pipe 40 or the muffler device 48, if the catalyst carrier 44 is formed in a honeycomb shape as described above, the area for supporting the catalyst metal increases, and the exhaust gas is Has the advantage of increasing the efficiency of causing an oxidation reaction upon contact with the catalyst, but since the ceramic material of the catalyst carrier is fragile and susceptible to vibration, the placement position is restricted, and it is particularly difficult to place it near an engine with strong vibration. There is a problem that can not be. In addition, since the ceramic as a material of the catalyst carrier is resistant to heat and does not corrode like metal, there is no problem such as peeling of the catalyst metal due to corrosion, but the metal case itself for accommodating and supporting the catalyst carrier is corroded. If this happens, the catalyst carrier holding force of the metal case is weakened, and there is also a problem that the catalyst carrier is displaced from the metal case due to vibration or the like during use and the catalyst carrier is broken. In order to solve this problem, an interram mat may be interposed as a protective sheet between the catalyst carrier and the metal case. However, since this interram mat is non-corrosive, the problem of a decrease in holding force due to corrosion as described above is solved, but since it is made by laminating alumina thin films in layers, it is once subjected to heat treatment. In the state of expansion beforehand, it is not possible to obtain a holding force unless it is compressed, high temperature exhaust gas passes during engine start, and in an exhaust pipe cooled by outside air during engine stop. When used for a long period of time, there is a problem that the shape is destroyed due to repeated expansion and contraction due to the temperature difference, and the holding power is lost. The present invention solves the above-mentioned problems related to the conventional method for supporting a ceramic catalyst carrier, and considers a catalyst carrier made of ceramic in consideration of corrosion of a support member, cracking due to vibration, or shape destruction of a protective sheet. It is an object of the present invention to provide a ceramic catalyst carrier supporting method and an exhaust device with a ceramic catalyst carrier that can be arranged without restriction at a desired position.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, a method for supporting a ceramic catalyst carrier according to the present invention comprises providing a ceramic catalyst carrier carrying a catalyst and a supporting member for supporting the catalyst carrier in a housing. A protective mat mainly composed of: is interposed in a compressed state without performing a heat expansion treatment, and the ceramic mat carrier is held on the supporting member by the protective mat. Further, the exhaust device with a ceramic catalyst carrier according to the present invention is configured such that the ceramic catalyst carrier carrying the catalyst is exhausted by a support member via a protective mat mainly composed of alumina in a compressed state without performing a heat treatment. It is characterized by being supported inside the device.

[0005]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a method for supporting a ceramic catalyst carrier according to the present invention; An embodiment of the apparatus will be described.

(Description of First Embodiment) FIGS. 1A and 1B
FIG. 2 is a schematic vertical sectional view of an exhaust pipe supporting a catalyst carrier by the support method of the present invention, and a partially enlarged view of a catalyst carrier holding portion. FIG. 2 is a cross-sectional view of the exhaust pipe of FIG. FIG. 3 is a cross-sectional view of the exhaust pipe as viewed from above. In the figure, reference numeral 1
Indicates a catalyst carrier. The catalyst carrier 1 is made of a ceramic material and formed in a honeycomb shape so as to form a large number of mesh-shaped ventilation passages. A catalytic metal such as platinum or rhodium is carried on all surfaces including the outer peripheral surface 1a. . The catalyst carrier 1 is provided with a bottomed carrier holding metal cylinder 3 having an open end. The metal tube 3 has an inner diameter r1 larger than the outer diameter R of the catalyst carrier 1, and has a bottom plate 3a.
Is formed with an opening 3b whose inner diameter r2 is slightly larger than the diameter R of the catalyst carrier 1. In addition, the carrier holding metal 3
Is dimensioned to be at least shorter than the catalyst carrier 1 so as not to cover the entire outer surface 1a of the catalyst carrier 1, and preferably to a minimum length capable of holding the catalyst carrier 1. Between the inner surface 3c of the carrier holding metal 3 and the outer surface 1a of the catalyst carrier 1, a cylindrical protective mat 5 mainly composed of alumina is interposed. Further, a retainer 7 is attached to the end of the carrier holding metal 3 opposite to the bottom plate 3a, and the protection mat 5 is shifted forward and backward by the retainer 7 and the bottom plate 3a of the carrier holding metal tube 3 due to vibration or the like. , From the space between the carrier holding metal tube 3 and the catalyst carrier 1. The protective mat 5 is a flocculent material containing alumina as a main component. As shown in FIG. 1B, both ends of the protective mat 5 are fixed with a ceramic adhesive 6 so that the protective mat does not come off during use. Is configured. Also,
The protection mat 5 is formed so that at least the inner diameter thereof is smaller than the outer diameter R of the catalyst carrier 1 in a state where the heat treatment is not performed.
After mounting, the catalyst carrier 1 is press-fitted so as to push and spread the protection mat 5. Thus, when the catalyst carrier 1 is assembled to the metal tube 3, the protection mat 5 is in a sufficiently compressed state, and the restoring force holds the catalyst carrier 1 on the metal tube 3. As shown in FIG. 1 (b), when the metal tube 3 is assembled, when the inner surface of the retainer 7 and the outer surface 1a of the catalyst carrier 1, and the bottom plate 3a of the metal tube 3 and the outer surface 1a of the catalyst carrier 1, The inner diameter of the retainer 7 and the opening of the bottom plate 3a are dimensioned so that there is a slight gap between them.
The catalyst carrier 1 is held in the metal tube 3 only by the protection mat 5. The metal tube 3 to which the catalyst carrier 1 is assembled as described above is fixed to four rod-like flanges 9 extending radially inward from the inner surface of the exhaust pipe 8 by appropriate means such as welding.

(Effect of the First Embodiment) According to the exhaust pipe 8 to which the catalyst carrier 1 is attached as described above, the catalyst carrier 1
Is formed in a rod shape, the exhaust gas can pass both inside and outside of the catalyst carrier 1,
The exhaust resistance by providing the catalyst carrier 1 can be reduced. In addition, since the catalyst carrier 1 formed in a honeycomb shape is held by the short metal tube 3 so that the outer peripheral surface 1a of the catalyst carrier 1 is sufficiently exposed from the metal tube 3, the exhaust gas passes through the catalyst carrier 1. At times, the area where the exhaust gas contacts the catalyst metal can be made very large, and the purification efficiency of the exhaust gas can be made very high. Further, as described above, the catalyst carrier 1 is held in the metal tube 3 only by the protective mat 5 mainly composed of alumina which does not cause oxidative corrosion or shape destruction due to heat such as a metal or an interram mat. Therefore, for example, as compared with the case where the catalyst carrier 1 is directly held by the metal tube 3, the duration of the holding force on the catalyst carrier 1 is very long, and as a result, the cycle of replacing the catalyst carrier 1 is lengthened. be able to. In addition, since the protective mat 5 acts as a cushioning material and attenuates the vibration transmitted to the catalyst carrier itself, the catalyst carrier formed of ceramic may have relatively large vibration, for example, near an engine having a high exhaust gas temperature. It can also be arranged in a part, and the purification efficiency can be increased.

(Explanation of Second Embodiment) FIGS. 3 and 4 show a second embodiment of an exhaust pipe supporting a catalyst carrier according to the supporting method of the present invention. FIG. FIG. 4 shows a schematic longitudinal sectional view, and FIG. 4 shows a transverse sectional view of the exhaust pipe viewed from the left side in FIG. In the figure, reference numeral 11 indicates a catalyst carrier. As in the case of the catalyst carrier 1 of the first embodiment, the catalyst carrier 11 is formed by forming a ceramic material into a honeycomb shape and carrying a catalyst metal on all surfaces including the outer peripheral surface 11a. At both ends of the catalyst support 11, two metal cylinders 13 for holding a bottomed support, one end of which is open, are mounted. Each of these two metal cylinders 13 has an inner diameter r1 ′ larger than the diameter R ′ of the catalyst carrier 11, and their bottom plate 13 a has an inner diameter r1 larger than the diameter R ′ of the catalyst carrier 11.
An opening 13b with a small 2 'is formed. Further, these metal tubes 13 cover only the vicinity of the end of the catalyst carrier 11,
The outer surface 11a of the catalyst carrier 11 is formed with a short dimension so that it can be exposed as widely as possible. Between the inner surface 13c of these two metal tubes 13 and the outer surface 11a of the catalyst carrier 11, a protective mat 15 containing alumina as a main component is interposed similarly to the first embodiment. At the open end of the tube 13, the protective mat 15 does not fall off.
Retainers 17 for retaining are attached. The configuration of the protection mat 15 itself is the same as the configuration of the protection mat 5 of the first embodiment, and the assembly process of the protection mat 15, the metal tube 13, and the catalyst carrier 11 is the same as the assembly process of the first embodiment. Since this is almost the same as the above, the description is omitted here. On the outer surface 13d of the two metal tubes 13 on which the catalyst carrier 11 is assembled, four rod-shaped support members 14 are fixed at 90-degree intervals so as to bridge the two metal tubes 13, and the inner surface of the exhaust pipe 18 Four rod-shaped flanges 19 are fixed to the outer surface of the rod-shaped support member 14 by a suitable method such as welding before and after extending inward in the radial direction.

(Effects of the Second Embodiment) According to the exhaust pipe 18 to which the catalyst carrier 11 is attached as described above, substantially the same effects as those of the first embodiment are obtained as a whole. further,
According to the exhaust pipe 18 of the second embodiment, the two metal tubes 13 support both ends of the catalyst carrier 11, and the four rod-shaped support members 14 are provided so as to span the two metal tubes 13. Since the catalyst carrier 11 is supported in the exhaust pipe 18 by the eight rod-shaped flanges 19 through the intermediary of the first embodiment, the support strength is higher than that of the catalyst carrier 1 in the first embodiment.

(Explanation of Third Embodiment) FIGS. 5 and 6 show a third embodiment of an exhaust pipe supporting a catalyst carrier by the supporting method of the present invention, and FIG. FIG. 6 shows a schematic longitudinal sectional view, and FIG. 6 shows a transverse sectional view of the exhaust pipe viewed from the left side in FIG. In the figure, reference numeral 21 indicates a catalyst carrier. The catalyst carrier 21 is formed by stacking ceramic materials in a honeycomb shape so as to form a large number of mesh-shaped ventilation passages to form a cylindrical shape, and the catalyst metal is supported on all surfaces including the outer peripheral surface 21a. . A protective mat 23 formed in a cylindrical shape is provided in a through hole of the catalyst carrier 21. This protective mat 23 is a cotton-like body containing alumina as a main component, as in the first and second embodiments, and its end is fixed with a ceramic adhesive 24 so that it cannot be released from the end during use. It is processed as follows. This protection mat 2
5 may be formed in a cylindrical shape from the beginning, but FIG.
As shown in (d), the plate-like protection mat 25 in which a plurality of slits are formed is rounded into a cylindrical shape, and the catalyst carrier 2 is formed.
It may be inserted into one through hole. Further, the catalyst carrier 21
Are provided with support rings 26 at both ends. These support rings 26 are provided so as to cover the outer peripheral edge of the catalyst carrier 21 and the through-hole of the catalyst carrier 21 to prevent the protective mat 25 provided in the through-hole from falling off. The inner ring 26b is connected by four connecting flanges 26c. As described above, the carrier holding rod 27 is attached to the catalyst carrier 21 to which the protection mat 25 and the two support rings 26 are attached. The carrier holding rod 27 is dimensioned so that its outer diameter R1 is at least larger than the inner diameter r3 of the cylindrical protective mat 25 inserted into the through hole of the catalyst carrier 21. , And the protective mat 25 is press-fitted so as to be expanded. Thereby, the carrier holding rod 2
When 7 is assembled to the catalyst carrier 21, the protective mat 25 is in a compressed state, and the restoring force holds the catalyst carrier 21 on the carrier holding rod 27. Although not shown in the drawings, when the carrier holding rod 27 is assembled to the catalyst carrier 21,
In order to have a slight gap between the inner surface of the inner ring 26b of the support ring 26 and the outer surface of the carrier holding rod 27,
The inner diameter of the inner ring 26b is dimensioned, so that the catalyst carrier 21 is composed of only the protection mat 25 and the carrier holding rod 2
7 is held. As described above, the carrier holding rods 27 assembled to the catalyst carrier 21 are fixed to the four rod-like flanges 29 before and after extending radially inward from the inner surface of the exhaust pipe 28 by appropriate means such as welding. .

(Effects of Third Embodiment) According to the exhaust pipe 28 to which the catalyst carrier 21 is attached as described above, substantially the same effects as those of the first embodiment are obtained as a whole. further,
According to the exhaust pipe 28 of the third embodiment, the catalyst carrier 21
The carrier support rod 27 is passed through the exhaust pipe 2 through a rod-like flange 29 before and after the catalyst support 21.
8 so that the first and second embodiments can be compared with the first and second embodiments.
The influence of the shape of the exhaust pipe on the outer diameter of the catalyst carrier and the arrangement in the exhaust pipe is small.

(Explanation of the Fourth Embodiment) FIG. 8 shows an embodiment in which a protective mat 25 is prevented from coming off by using a retainer instead of the support ring 26 in the third embodiment. It is a longitudinal cross-sectional view, and the code | symbol 33 has shown the retainer in the figure. As described above, if the protective mat 25 is configured to be prevented from coming off only by the retainer 33, the exposed area of the catalyst carrier 31 can be made wider than that of the catalyst carrier 21 of the third embodiment shown in FIGS. And the purifying action can be further enhanced. Since FIG. 8 has the same configuration as the third embodiment shown in FIG. 5 except for the retainer 33, the same members as those in the third embodiment are denoted by the same reference numerals, and details of each part are described. Detailed description is omitted.

(Explanation of an example in which a catalyst carrier is provided in a tapered portion of an exhaust pipe) FIG. 9 shows an example in which a catalyst carrier is arranged in a tapered portion of an exhaust pipe using the structure of the first embodiment. FIG. 3 is a schematic view of a tapered portion of a tube, and the reference numerals in this figure use the same reference numerals as those in the first embodiment shown in FIGS. According to the configuration of the first embodiment, the catalyst carrier 1
Can be supported inside the exhaust pipe 8 by the rod-shaped flange 9, the exhaust resistance by providing the catalyst carrier 1 can be extremely reduced, and as shown in FIG.
Can be provided continuously. The same can be said for the second and third embodiments.

(Others) In the above embodiment, the ends of the protection mats 5, 15, and 25 are fixed with a ceramic adhesive to prevent the protection mat from coming off from the ends during use. Various methods can be considered for this unwinding treatment without being limited to the present embodiment. For example, as shown in FIG. 10, a metal foil is attached to the end of the protective mat to prevent unwinding. You may. In the above-described embodiment, the carrier holding metal cylinders 3 and 13 (or the carrier holding rod 27) are used.
And the rod-shaped flanges 9, 19 and 29 are formed separately, but this is not limited to the present embodiment, and a member for holding the catalyst carrier and a member for supporting the member in the exhaust pipe are provided. You may comprise integrally. Further, in the above-described embodiment, the protective mat is mainly composed of alumina, but the component of the protective mat may be any component as long as it is mainly composed of alumina, such as alumina alone or alumina silica. obtain.

[0015]

According to the method for supporting a ceramic catalyst carrier of the present invention described above, the support member and the ceramic catalyst carrier are compressed in a state in which the protective mat containing alumina as a main component is compressed without being subjected to heat expansion treatment. Because it is interposed between
The rate of expansion and contraction depending on the temperature change of the protective mat can be reduced, and as a result, the shape breakage due to the temperature change is less likely to occur, and a stable holding ability to the catalyst carrier can be obtained. Therefore, since the ceramic catalyst carrier can be held by the protective mat having a stable holding ability, the ceramic catalyst carrier can be placed at a desired position, for example, near the engine where the reaction efficiency of the catalyst metal is high, without any restrictions. It becomes possible to do. Further, according to the exhaust device with a ceramic catalyst carrier according to the present invention, the ceramic catalyst carrier is supported inside by a support member via a protective mat containing alumina as a main component in a compressed state without performing heat treatment. The durability of the protective mat has been extended,
As a result, there is an effect that the use period of the catalyst carrier can be sufficiently long.

[Brief description of the drawings]

1 (a) is a schematic longitudinal sectional view of an exhaust pipe supporting a catalyst carrier according to the supporting method of the present invention, and FIG. 1 (b) is FIG.
It is the elements on larger scale of (a).

2 is a cross-sectional view of the exhaust pipe of FIG. 1 as viewed from the left side in FIG. 1;

FIG. 3 is a schematic vertical sectional view of an exhaust pipe according to a second embodiment.

FIG. 4 is a cross-sectional view of the exhaust pipe viewed from the left side in FIG.

FIG. 5 is a schematic vertical sectional view of an exhaust pipe according to a third embodiment.

FIG. 6 is a cross-sectional view of the exhaust pipe viewed from the left side in FIG.

FIGS. 7A to 7D are views showing a process in which a plate-shaped protective mat 25 having a plurality of slits is rolled into a cylindrical shape, and inserted into a through hole of a catalyst carrier 21. FIGS.

FIG. 8 is a schematic longitudinal sectional view of an exhaust pipe according to a fourth embodiment in which a part of the third embodiment is modified.

FIG. 9 is a schematic diagram of a tapered portion of an exhaust pipe showing an example in which a catalyst carrier is disposed on the tapered portion of the exhaust pipe using the configuration of the first embodiment.

FIG. 10 is a view showing another embodiment of a method for preventing the end of the protection mat from being loosened.

FIGS. 11A and 11B are schematic diagrams of an exhaust device showing a conventional supporting method.

[Explanation of symbols]

 (First Example) 1 Catalyst carrier 1a Outer peripheral surface 3 Carrier holding metal tube 3a Bottom plate 3b Opening 3c Inner surface 5 Protective mat 6 Ceramic adhesive 7 Retainer 8 Exhaust pipe 9 Rod flange R Catalyst carrier outer diameter r1 Carrier holding metal tube Inner diameter r2 inner diameter of bottom plate opening (second embodiment) 11 catalyst carrier 11a outer peripheral surface 13 carrier holding metal tube 13a bottom plate 13b opening 13c inner surface 13d outer surface 15 protection mat 17 retainer 18 exhaust pipe 19 rod-shaped flange R 'outside of catalyst carrier Diameter r1 'Inner diameter of carrier holding metal cylinder r2' Inner diameter of opening of bottom plate (third embodiment) 21 Catalyst carrier 21a Outer peripheral surface 23 Protective mat 24 Ceramic adhesive 25 Protective mat 26 Support ring 26a Outer ring 26b Inner ring 26c Connection Flange 27 Carrier holding rod 28 Exhaust pipe 29 Rod flange R1 Carrier holding rod Outer diameter r3 cylindrical protective mat size (Fourth Embodiment) 31 catalyst carrier 33 retainer (prior art) 40 exhaust pipe 40a inner wall 42 catalyst 44 catalyst carrier 46 supporting member 48 muffler device 50 expansion chamber dividing wall

Claims (2)

[Claims] 1. A state in which a protective mat containing alumina as a main component is compressed between a ceramic catalyst carrier supporting a catalyst and a support member supporting the catalyst carrier in a housing without performing a thermal expansion treatment. A method for supporting a ceramic catalyst carrier, comprising interposing and holding the ceramic catalyst carrier on the support member with the protective mat. 2. A ceramic catalyst carrier supporting a catalyst is supported inside a gas exhaust unit by a supporting member via a protective mat containing alumina as a main component in a compressed state without being subjected to a heat treatment. Exhaust device with ceramic catalyst carrier.