JP3267840B2 - Metal carrier for exhaust gas purification catalyst and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a metal carrier for an exhaust gas purifying catalyst installed in an exhaust gas system for purifying exhaust gas discharged from an engine such as an internal combustion engine and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, a metal carrier has been used as a catalyst carrier for purifying an engine exhaust gas of an automobile, rather than a ceramic carrier.
The metal carrier consists of a flat foil made of a heat-resistant metal and a corrugated foil that has been processed into a corrugated shape, and a honeycomb body that is wound and laminated in a spiral shape is inserted into an outer cylinder made of a heat-resistant metal. The flat foil and the corrugated foil, and the honeycomb body and the outer cylinder are mainly joined by a brazing material. Then, a precious metal such as Pt is supported on the honeycomb body as a catalyst.

A metal carrier, particularly a honeycomb body, installed in an exhaust gas system comes into direct contact with high-temperature exhaust gas and becomes hot due to heat generated by a catalytic reaction, but the outer cylinder is exposed to outside air and radiated heat. Then, the outer cylinder and the honeycomb body near the outer cylinder are cooled. That is, when a temperature difference is generated between the inside and outside of the metal carrier in the radial direction, and the outer cylinder and the honeycomb body are integrally joined, the honeycomb body near the outer cylinder, which is weak in strength, is damaged by thermal distortion. Sometimes.

[0004] For this purpose, the outer cylinder and the honeycomb body are not entirely joined to form a rigid joined body, but are partially joined to increase the free state. Means for preventing the temperature from dropping are presented. For example, in Japanese Utility Model Laid-Open Publication No. 2-32935,
As shown in FIG. 2, there is disclosed a catalyst structure having a configuration in which a porous heat insulating material 22 is filled around a honeycomb body 21 on an exhaust gas injection side. Japanese Patent Application Laid-Open No. 5-57197 discloses that, as shown in FIG. 3, an outer cylinder 32 is disposed coaxially on the outer periphery of a honeycomb body 31 and is interposed between the honeycomb body and the outer cylinder. The intermediate cylinder 33 has low rigidity, and the honeycomb body and the intermediate cylinder, and the intermediate cylinder and the outer cylinder are partially joined to each other.
A metal carrier is disclosed in which a heat insulating layer 35 is provided on each of these surfaces except for a joint portion and an air layer is interposed in a space.

Further, Japanese Patent Application Laid-Open No. 6-126191 discloses that a ring 42 having a width shorter than the axial length of the honeycomb body is joined to the outer periphery of the honeycomb body 41 and the outer cylinder 43 and the ring 42 are joined together.
An exhaust gas purifying apparatus is disclosed in which an inflatable seal 44 is interposed between the outer casing 43 and a heat insulating material 45 between the outer casing 43 and the honeycomb body 41.

[0006]

In each of the metal carriers described in these publications, a heat insulating material is interposed between the outer peripheral portion of the honeycomb body and the outer cylinder, so that the metal carrier can easily be cooled (heat dissipation property). ) to improve, in which is intended to further improve the purification performance of the exhaust gas by improving the warm air resistance. However, these carriers require a process of filling or adhering a heat insulating material, providing an intermediate tube and joining them, and further winding an inflatable seal, thereby increasing the number of production processes and increasing costs. There was a problem of becoming.

[0007] From the state of such techniques, the present invention without the use of heat insulating material or the like, by providing a heat insulating layer to the honeycomb body outer peripheral portion in a very simple manner, with excellent warm air resistance and anti-heat radiation An object of the present invention is to provide an inexpensive metal carrier for an exhaust gas purifying catalyst and a method for producing the same.

[0008]

To accomplish the above object means to provide a process, a honeycomb body formed of a metallic flat foil and corrugated foil are laminated wound alternately, a metal outer cylinder An exhaust gas, wherein a metal carrier that is inserted and appropriately joined is provided with a heat insulating layer that seals both end portions of several turns from the outermost periphery of the honeycomb body and maintains the sealed portion in a vacuum. A metal material for purification catalyst, and a brazing material are supplied to the cells at both end portions in several turns from the outermost periphery of the honeycomb body inserted into the outer cylinder via an adhesive, and the cell holes are closed to produce a metal carrier. A gist of the present invention is a method for producing a metal carrier for an exhaust gas purifying catalyst, which comprises performing a high-temperature bonding treatment in a vacuum atmosphere in a process.

Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a front view of the metal carrier of the present invention (a).
FIG. 1B is a cross-sectional view taken along line AA of FIG. 1, in which a honeycomb body 3 formed by superimposing a flat foil 1 and a corrugated foil 2 and spirally stacking them is inserted into an outer cylinder 4. The flat foil 1 and the corrugated foil 2 come into contact with the flat foil at the peaks and valleys of the corrugated foil, and join predetermined portions of the contact portions. The outer periphery of the honeycomb body 3 and the inner periphery of the outer cylinder 4 are also joined, and reference numeral 5 denotes the joined portion. The bonding may be performed by a brazing method, a heat diffusion method, or any other method.

In the figure, reference numeral 6 denotes a heat insulating layer which is a feature of the present invention, and is composed of several turns, preferably 1 to 3 turns inside the outermost periphery of the honeycomb body 3 wound with the flat foil 1-corrugated foil 2. The heat insulating layer 6 seals the cell holes 9 of the several turns on both end faces 7 and 8 in the axial direction of the honeycomb body 3 with a plugging material 10 to maintain a reduced pressure atmosphere. The sealing material 10 is preferably a brazing material, and in the case where the cell holes 9 are coarse, a heat-resistant ring processed and formed so as to match the shape of the closing portion can be used. To seal the cell hole.
The reason why the atmosphere of the heat insulating layer 6 is maintained in a vacuum (a reduced pressure atmosphere) is that the heat insulating effect is larger than that of the atmosphere.

Usually, the metal carrier is heated and heated at a high temperature in a vacuum after the brazing material is supplied and adhered to a predetermined position of the honeycomb body, or in the case of diffusion bonding, without supplying the brazing material. That is, in the case of the brazing, the powder wax is sprayed from the upper end surface of the honeycomb body to which an adhesive has been applied so that the brazing material adheres to the predetermined position in advance, and is attached to the predetermined position inside the honeycomb body. . In particular, it is preferable to adhere the entire length to the contact portion between the flat foil 1 and the corrugated foil 2 at several turns, preferably 1 to 3 turns, on the outer peripheral side of the honeycomb body. Also, a powdered brazing material is adhered to the cell holes of the outer peripheral side several turns on both end surfaces 7 and 8 of the honeycomb body using a binder or the like. At this time, it is not necessary that the powdered brazing material is always adhered to the cell holes so as to completely close the cell hole. Just do it.

After the brazing material is attached in this manner, the metal carrier is inserted into a vacuum heating furnace and heated to about 1200 ° C. in a reduced pressure (10 ⁻³ torr or less) atmosphere, thereby joining the flat foil to the corrugated foil. At the same time, while the inside of the honeycomb body is kept in a vacuum, both ends of the cell holes having the several turns on the outer peripheral side are melted and tightly closed by the brazing material to form the heat insulating layer 6.

The reason why the heat insulating layer 6 is formed to have a plurality of turns on the outer peripheral side is a portion which is most likely to dissipate heat close to the outer cylinder, and furthermore, a flat wave is formed to strengthen the connection between the outer cylinder and the honeycomb body. This is because it is a part for joining the foils, and is therefore effective for maintaining a vacuum. The preferred number of turns of the heat insulating layer is about 1 to 3 turns on the outermost periphery of the honeycomb body.

[0014]

EXAMPLE A flat plate made of a heat-resistant metal and having a thickness of 50 μm,
After applying a binder to the corrugated portion of the corrugated foil by a roll coater method using a corrugated plate obtained by corrugating the flat plate, the corrugated plate is superposed and wound on the flat plate, and has a diameter of 86 mmφ and a length of 1 mm.
A 20mm honeycomb body was produced. A brazing material was sprayed from the upper portion of the honeycomb body, and the brazing material was attached to the contact point between the flat plate and the corrugated plate. A foil was attached to the outer periphery of the honeycomb body, and the honeycomb body was charged into a heat-resistant metal outer cylinder having a thickness of 1.5 mm, a diameter of 89 mmφ, and a length of 120 mm.

The joining structure was a whole joining. Paste wax was filled into both ends of the three layers on the outer peripheral side of the honeycomb body to a depth of 2 mm from the end face, and this was charged into a vacuum heat treatment furnace.
As the vacuum heat treatment conditions, the atmosphere is a degree of vacuum of 1 × 10 ^-3 torr
And heated to 1200 ° C. and held for 30 minutes.

[0016] In order to investigate the warm care, especially <br/> of the metal carrier that was produced in this manner, the temperature was measured by attaching the metal support to the exhaust pipe of the 2000cc engine. The measurement temperature was set at 800 ° C. and 600 ° C. at the gas temperature on the metal carrier inlet side. As a comparison, a metal carrier having the same dimensions and the same joining structure as the above-mentioned embodiment and having no heat insulating structure with three layers on the outer peripheral side was used.
The temperature was measured by providing a sheath thermocouple on the cross section of the metal carrier in the center in the longitudinal direction. Tables 1 and 2 show the measurement results.

[0017]

[Table 1]

[0018]

[Table 2]

As is clear from Tables 1 and 2, the heat insulating effect of the product of the present invention shows an extremely good result in each case. That is, in the product of the present invention, since the temperature rise near the outer cylinder is fast, the effective area of the catalytic activity is widened. Therefore, a metal carrier having high purification performance can be provided.

[0020]

As described above, in the honeycomb body of the present invention, a heat insulating layer is provided on the outer peripheral portion of the honeycomb body by using a usual method of manufacturing a metal carrier without using a heat insulating material or the like. can be, good exhaust gas purification catalyst for metal carrier warm air resistance and anti-heat radiation can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a metal carrier of the present invention, wherein (a) is a front view thereof, and (b) is a cross-sectional view taken along line AA of (a).

FIG. 2 shows a partial cross-sectional view of a conventional metal carrier.

FIG. 3 shows a cross-sectional view of another conventional metal carrier.

FIG. 4 shows a sectional view of another conventional metal carrier.

[Explanation of symbols]

 1: flat foil 2: corrugated foil 3: honeycomb body 4: outer cylinder 5: joint 6: heat insulating layer 7, 8: end face of honeycomb body 9: cell hole 10: plugging material

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B01J 21/00-37/84 B01D 53/86 B01D 53/94 F01N 3/28

Claims (2)

(57) [Claims] The method according to claim 1] Metal flat foil and corrugated foil and a honeycomb body formed by laminating alternately wound, inserted into a metal outer cylinder,
A metal carrier for an exhaust gas purifying catalyst, wherein a metal carrier configured by being appropriately joined is characterized in that both end portions of several turns from the outermost periphery of the honeycomb body are sealed, and the sealed portion is formed as a heat insulating layer that is kept in a vacuum. Carrier. 2. A brazing material is supplied to the cells at both end portions of several turns from the outermost periphery of the honeycomb body inserted into the outer cylinder via an adhesive, and the cell holes are closed to form a vacuum in the metal carrier manufacturing process. A method for producing a metal carrier for an exhaust gas purifying catalyst, comprising performing a high-temperature bonding treatment in an atmosphere.