JPH078029Y2 - Metal honeycomb catalytic converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a metal honeycomb catalytic converter provided in an exhaust system of an automobile engine or the like.

(Prior Art) As a catalytic converter used as a countermeasure for exhaust gas of an automobile, there is, for example, one shown in FIGS. 3 and 4 (see Japanese Patent Laid-Open No. 54-13462).

This is called a metal honeycomb catalyst converter, and a flat metal foil 1 and a corrugated metal foil 2 are polymerized and wound to form a large number of passages 3 in a honeycomb shape. Carry.

The catalyst carrier 4 has the outer peripheral portion 5 with the inner wall surface 7 of the case 6.
HC, CO, NO in the exhaust gas that passes through the passage 3 of the catalyst carrier 4 while being housed and held by being joined to the engine 6 and also installed in the middle of the exhaust pipe of the engine through the flanges 8 at both ends of the case 6. It is designed to oxidize and reduce harmful components such as.

(Problems to be solved by the invention) However, in such a catalytic converter,
While the catalyst carrier 4 becomes extremely hot due to the hot exhaust gas and its reaction heat, the case 6 is exposed to the outside air and does not become so hot, so that thermal deformation or the like is likely to occur.

That is, although the catalyst carrier 4 tends to expand greatly due to high heat, the case 6 does not expand so much, which imposes an excessive thermal stress on the catalyst carrier 4. Therefore, if the catalyst carrier 4 is used for a long time, As shown in FIGS. 6 and 6, the metal foils 1 and 2 forming the catalyst carrier 4 are cracked or the passages 3 are crushed.

The present invention aims to solve such a problem.

(Means for Solving Problems) The present invention relates to a catalyst converter in which a catalyst carrier carrying a catalyst in each of the honeycomb-shaped passages is stored and held in a state of being in direct contact with the inner surface of the case. The catalyst carrier is formed by polymerizing and winding a flat metal foil made of a ferritic stainless steel material and a corrugated metal foil, and the case is made of an austenitic stainless material.

(Operation) In the above structure, the case made of the austenitic stainless steel material causes a larger thermal expansion than the catalyst carrier made of the ferritic stainless steel material. It does not generate any stress.

(Embodiment) FIG. 1 and FIG. 2 are a lateral cross-sectional view and a partially enlarged view of a catalytic converter showing an embodiment of the present invention, in which a catalyst is attached to each surface of a plurality of passages 11 formed in a honeycomb shape. The catalyst carrier to be carried, 12 is the case of the catalyst carrier 10.

The catalyst carrier 10 is made of a ferritic stainless steel material (for example,
20Cr-5Al etc.) flat metal foil 13 and corrugated metal foil 1
By overlapping and winding 4 and 4, a large number of passages 11 are formed in a honeycomb shape as shown in the figure.

On the other hand, the case 12 is formed of an austenitic stainless steel material (for example, SUS304) having a linear expansion coefficient larger than that of the ferritic stainless steel material forming the catalyst carrier 10, and the outer peripheral portion 15 of the catalyst carrier 10 is formed on the inner wall surface 16 of the case 12. It is formed so as to accommodate and hold the catalyst carrier 10 in a state of being in direct contact with.

In this case, the cross sections of the catalyst carrier 10 and the case 12 are formed in an oval shape as shown in the drawing, but may be circular as shown in FIG. Further, the case 12 is provided with flanges at both ends for connecting to the exhaust pipe of the engine, as in FIG.

That is, when the catalytic converter is used, the catalyst carrier 10 receives a high temperature exhaust gas and reaction heat to reach a considerably high temperature (eg, 800 ° C.) and tries to expand according to the temperature.
Since the case 12 for accommodating is formed of a metal material having a larger linear expansion coefficient than the metal material of the catalyst carrier 10, the coefficient of thermal expansion of the case 12 is high, and therefore the temperature of the case 12 is compared by being exposed to the outside air. Even if the temperature is extremely low, the thermal stress caused by the thermal expansion of the catalyst carrier 10 is relaxed.

Therefore, the catalyst carrier 10 is not unduly applied with thermal stress, which can prevent cracks in the metal foils 13 and 14 forming the catalyst carrier 10 and can prevent the passage 11 from being crushed, and thus the heat resistance can be improved. The durability and the durability can be improved.

The linear expansion coefficient of ferritic stainless steel is 0-800.
Approximately 11.5 × 10 ^-6 / ° C at 0 ° C, and the linear expansion coefficient of austenitic stainless steel material is approximately 16.5 × 10 ^-6 / ° C at 0 to 400 ° C. When the case 12 is formed, the thermal expansion amount of the case 12 approaches the thermal expansion amount of the catalyst carrier 10 under the temperature conditions of the catalyst carrier 10 and the case 12 (for example, 800 ° C. for the catalyst carrier 10 and 400 ° C. for the case 12). , The thermal stress generated is sufficiently small.

The case 12 may be formed of SUS310S which has high strength at high temperature among austenitic stainless steels.

(Effect of the Invention) As described above, according to the present invention, the catalyst carrier is made of a ferritic stainless steel material and is held so as to be in direct contact with the case made of an austenitic stainless steel material having a larger linear expansion coefficient. As a result, under conditions where the temperature of the catalyst carrier rises with respect to the case, heat conduction from the catalyst carrier to the case can be promoted to reduce the temperature difference between the two and to alleviate the stress applied to the catalyst carrier by thermal expansion. This makes it possible to obtain the effect of improving the heat resistance and durability of the metal honeycomb catalytic converter.

Further, according to the present invention, since the structure in which the catalyst carrier is directly housed in the case can be easily adopted, a larger catalyst carrier can be used as compared with, for example, a ceramic catalyst converter in which the carrier is held via a cushion material. The volume can be secured or the catalytic converter can be downsized.

Further, the metal foil made of ferritic stainless steel material forming the catalyst carrier has good workability, while the austenitic stainless steel material forming the case has excellent tensile strength, so that each characteristic of each stage of production and use should be utilized. It is possible to improve productivity and reliability.

[Brief description of drawings]

1 and 2 are cross-sectional views showing an embodiment of the present invention and a partially enlarged view thereof, and FIGS. 3 and 4 are vertical cross-sectional views and cross-sectional views of a conventional example, FIG. 5 and FIG. FIG. 4 is an explanatory view showing a damaged state of a catalyst carrier. 10 ... Catalyst carrier, 11 ... Passage, 12 ... Case.

Claims (1)

[Scope of utility model registration request] 1. A catalyst converter in which a catalyst carrier carrying a catalyst in each of the honeycomb-shaped passages is accommodated and held in a state of being in direct contact with an inner surface of a case, the catalyst carrier being a ferrite stainless steel material. A metal honeycomb catalytic converter characterized in that it is formed by polymerizing and winding a flat metal foil and a corrugated metal foil made of, and the case is made of an austenitic stainless steel material.