JP2001065336A - Metal carrier catalytic converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal carrier catalytic converter capable of preventing breakage of a honeycomb structure and separation of it from an outside cylinder by securing free thermal expansion of the honeycomb structure and stably fixing itself on the outside cylinder. SOLUTION: This converter is a metal carrier catalytic converter inserting a honeycomb structure in an outside cylinder 30 and fixing them on each other, the outside cylinder 30 and the honeycomb structure 20 are fixed by sinking at least a part of both end outer peripheral parts of the outside cylinder 30 on an outer periphery of the honeycomb structure 20, and a clearance in the axial direction is provided between a sunk part of the outside cylinder 30 and the honeycomb structure 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal carrier catalytic converter which is provided in an exhaust system of an automobile or the like and is used for purifying exhaust gas. The present invention relates to a technique for preventing occurrence of cracks and preventing separation of the two and breakage of a honeycomb structure.

[0002]

2. Description of the Related Art Conventionally, as a catalyst for purifying exhaust gas, a metal carrier catalytic converter in which a metal honeycomb having a metal honeycomb structure coated with a catalyst containing platinum, rhodium, palladium or the like is inserted into an outer cylinder and fixed is used. Are known. Metal carrier catalytic converters have a thinner honeycomb structure compared to ceramics, so the time it takes to reach the catalyst activation temperature after starting the engine is shorter,
Further, it has a characteristic that exhaust resistance is small. Therefore, its application is expanding in recent years because it has a high exhaust gas purification capability and can improve the efficiency of the engine.

Here, a metal-supported catalytic converter is constructed by laminating a flat foil made of a heat-resistant metal having a thickness of 20 to 50 μm and a corrugated foil, and winding the flat foil into a cylindrical or columnar shape. The honeycomb structure is manufactured by inserting the honeycomb structure into an outer cylinder having a thickness of 1 to 2 mm. FIG. 7A is a diagram for explaining a method of fixing the honeycomb structure 1 and the outer cylinder 2. As shown in the figure, a brazing material 3 is applied or attached between the flat foil and the corrugated foil on both end faces of the honeycomb structure 1. Thereafter, the brazing material 4 is applied or attached to the outer periphery of the honeycomb structure 1 and the honeycomb structure 1 and the outer tube 2 are heated to fix the flat foil and the corrugated foil and to fix the honeycomb structure 1 and the outer tube 2 at the same time. Will be Alternatively, as shown in FIG. 7B, the flat foil and the corrugated foil of the honeycomb structure are fixed by laser spot welding, and the outer cylinder 2 and the honeycomb structure 1 are fixed by the brazing material 4 or laser welding. Have been done.

[0004]

By the way, the inside of the honeycomb structure becomes hot due to the passage of high-temperature exhaust gas, while the outer cylinder is cooled by being exposed to outside air. growing. However, since both ends of the honeycomb structure are fixed to the outer cylinder, the honeycomb structure that is about to undergo thermal expansion is restricted by the outer cylinder, and a large stress is generated in the honeycomb structure. For this reason, there is a problem that the honeycomb structure is subject to fatigue failure due to a thermal cycle, or the honeycomb structure is separated from an outer cylinder and deviated from a regular position.

As a fixing method that does not restrain the thermal expansion of the honeycomb structure, as shown in FIG. 7C, only one end of the honeycomb structure 1 in which the flat foil and the corrugated foil are fixed by the brazing material 3 is brazed by the brazing material 4. A method of fixing to the outer cylinder 2 is conceivable. However, in this method, when the honeycomb structure 1 is fixed to the outer cylinder 2, the brazing material 3 is melted by heating, and the honeycomb structure 1 and the outer cylinder 2 may be fixed at a portion other than the brazing material 4. . For this reason, the fixing of the honeycomb structure 1 and the outer cylinder 2 is performed at a plurality of locations, and as a result, the above-mentioned problems have not been solved. In this fixing method, the flat foil and the corrugated foil of the honeycomb structure 1 may be fixed by laser spot welding.
Is fixed to the outer cylinder 2 at one place, sufficient reliability against vibration input cannot be obtained. Therefore, the present invention provides a metal carrier catalytic converter that can secure free thermal expansion of the honeycomb structure to prevent breakage of the honeycomb structure and detachment from the outer cylinder, and that can be stably fixed to the outer cylinder. It is intended to be.

[0006]

A metal carrier catalytic converter according to the present invention is a metal carrier catalytic converter in which a honeycomb structure is inserted into an outer cylinder and fixed to each other. The outer cylinder and the honeycomb structure are fixed by being depressed on the outer periphery, and a gap in the axial direction is provided between the depressed portion of the outer cylinder and the honeycomb structure.

[0007] In the metal-catalyst catalytic converter having the above-described structure, since it is fixed to the outer cylinder at both ends of the honeycomb structure, not only the stability and reliability are improved but also the depressed portion of the outer cylinder is improved. Since the gap in the axial direction is provided between the honeycomb structure and the honeycomb structure, even if the temperature of the honeycomb structure rises and thermal expansion occurs, the honeycomb structure can move in the gap and the thermal expansion of the honeycomb structure is not restricted. Therefore, occurrence of troubles such as breakage of the honeycomb structure and detachment from the outer cylinder can be prevented.

Here, as a method of fixing the outer cylinder and the honeycomb structure, it is simple and inexpensive to caulk the outer cylinder with the honeycomb structure inserted therein. For example, three or four circumferentially separated places at both ends of the outer cylinder are pushed into the inner peripheral side to be plastically deformed. As a result, the caulked portion of the outer cylinder is depressed on the outer periphery of the honeycomb structure, and both are fixed. In this case, when the external force applied to the outer cylinder by the caulking is removed, the concave portion formed on the outer periphery of the honeycomb structure by the caulking is permanently deformed on the outer periphery of the honeycomb structure having a small thickness and low rigidity as a permanent deformation. Remains. On the other hand, the outer cylinder has high rigidity due to its thick wall,
For this reason, when the external force of caulking is removed, the portion that protrudes toward the inner circumference slightly returns to the outer circumference due to springback. As a result, a gap is formed between the depressed portion of the outer cylinder and the recess formed on the outer periphery of the honeycomb structure, and the honeycomb structure can move in the axial direction with respect to the outer cylinder by the gap. The caulking may be performed so as to narrow down the outer circumference of the outer cylinder over the entire circumference.

The above is a method in which a concave portion is formed on the outer periphery of the honeycomb structure by caulking. In this method, the cell in the portion where the concave portion on the outer periphery of the honeycomb structure is formed and the cells in several layers close to the concave portion are formed. Are crushed, and many parts cannot pass through the exhaust gas. Therefore, a concave portion can be formed in advance on the outer periphery of the honeycomb structure, so that a portion through which exhaust gas cannot pass can be minimized. For example, when a flat foil and a corrugated foil are overlapped and rolled from one end to produce a honeycomb structure, a band-shaped notch is formed in the flat foil and corrugated foil of a part of the circumference of two to three before the end of the winding. As a result, in the outer periphery of the honeycomb structure, a concave portion in which two or three layers of cells are missing is formed over the entire periphery. Then, the honeycomb structure is inserted into the outer cylinder, and the outer cylinder is caulked in accordance with the position of the concave portion.

[0010]

DETAILED DESCRIPTION OF THE INVENTION 1. First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a state in which a corrugated foil 13 is superimposed on a flat foil 12, and by winding this from one end, FIG.
As shown in FIG. 1, a honeycomb structure 20 having a plurality of cells 22,... Is formed. Next, a brazing material is applied or attached between the flat foil 12 and the corrugated foil 13 on both end faces of the honeycomb structure 20, and the brazing material is subjected to a heat treatment to thereby form the flat foil 12 and the corrugated foil 1.
3 is fixed. In addition, the thickness of the flat foil 12 and the corrugated foil 13 is set to 20 to 50 μm.

Next, as shown in FIG. 3, the honeycomb structure 2
0 is inserted into a cylindrical outer cylinder 30 having a thickness of 1 to 2 mm. Next, caulking is performed to deform three or four locations on the outer periphery of both ends of the outer cylinder 30 toward the inner periphery. As a result, a part of the outer cylinder 30 protrudes toward the inner peripheral side and the honeycomb structure 2
It sinks to the outer circumference of 0. By this caulking, the outer cylinder 30
Is formed on the outer periphery of the honeycomb structure 20 with a concave portion 23 having a shape substantially following the convex portion 31.
Is formed.

When the external force applied to the outer cylinder 30 due to caulking is removed, the honeycomb structure 20 having a small thickness and a low rigidity has:
Although the concave portion 23 remains in almost the same shape as permanent deformation, springback occurs in the outer cylinder 30 having a large thickness and high rigidity, and the convex portion 31 slightly returns to the outer peripheral side. This allows
A gap is formed between the convex portion 31 and the concave portion 23, and the honeycomb structure 20 can move in the axial direction with respect to the outer cylinder 30 by the gap. Therefore, even if the temperature of the honeycomb structure 20 rises and thermally expands, the honeycomb structure 20 can move in the gap, and the thermal expansion of the honeycomb structure 20 is not restricted. Therefore, occurrence of troubles such as breakage of the honeycomb structure 20 and detachment from the outer cylinder 30 can be prevented. Also, since the honeycomb structure 20 is fixed to the outer cylinder 30 at both ends,
The fixing is stable and the reliability is sufficient. Furthermore, the honeycomb structure can be fixed to the outer cylinder by simple processing called caulking without requiring strict management of the amount and positioning of the brazing material as in the conventional fixing method by brazing, so that manufacturing costs are reduced. Can be reduced. After the caulking of the outer cylinder 30 is completed, the honeycomb structure 20 is coated with a catalyst containing platinum, rhodium, palladium, or the like, and a metal carrier catalytic converter is completed.

[0013] 2. Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 4, parallel flat strips 14 are formed at one end of the flat foil 12 and the corrugated foil 13. Then, the flat foil 12 and the corrugated foil 13 are wound from one end on the right side to form a honeycomb structure 21 shown in FIG. The length of the notch 14 is approximately three turns before the end of the winding. Therefore, a concave portion 24 in which the cutouts 14 overlap by three layers is formed on the outer periphery of the honeycomb structure 21.

Next, as shown in FIG. 6, the honeycomb structure 2
1 is inserted into the outer cylinder 30 similar to the above. Next, at the positions of the concave portions 24, 24 of the honeycomb structure 21, crimping is performed to deform three or four portions of the outer cylinder 30 to the inner peripheral side. As a result, a part of the outer cylinder 30 projects toward the inner peripheral side and falls into the concave portion 24 of the honeycomb structure 21. The convex portion 31 and the concave portion 24 formed on the outer cylinder 30 by this caulking work engage, and the honeycomb structure 21 is fixed to the outer cylinder 30.

As shown in FIG. 6, an axial gap is formed between the concave portion 24 of the honeycomb structure 21 and the convex portion 31 of the outer cylinder 30. Therefore, even if the temperature of the honeycomb structure 21 rises and thermally expands, the honeycomb structure 21 can move in the gap, and the thermal expansion of the honeycomb structure 21 is not restricted. Therefore, occurrence of troubles such as breakage of the honeycomb structure 21 and detachment from the outer cylinder can be prevented. Further, in the first embodiment, the convex portions 31 of the outer cylinder 30 crush several layers of the cells 22 adjacent to the concave portions 23 of the honeycomb structure 20, and a portion where the exhaust gas indicated by the thickness T in the drawing does not flow is removed. However, in the second embodiment, the thickness T can be reduced by setting the depth of the concave portion 24 to the amount of protrusion of the convex portion 31. Therefore, a decrease in exhaust gas purification efficiency can be suppressed.

In the second embodiment, the recesses 24 are formed in the honeycomb structure 21 by forming the notches 14 in the flat foil 12 and the corrugated foil 13, but the recess 24 is formed in the outer periphery of the honeycomb structure 20 shown in FIG. Alternatively, the concave portion can be processed by machining or the like.

[0017]

As described above, in the present invention,
At least a part of the outer periphery of both ends of the outer cylinder is depressed at the outer periphery of the honeycomb structure to fix the outer cylinder and the honeycomb structure, and
Since a gap in the axial direction is provided between the depressed portion of the outer cylinder and the honeycomb structure, even if the temperature of the honeycomb structure rises and thermal expansion occurs, the honeycomb structure can move within the gap, and the thermal expansion of the honeycomb structure is reduced. Without being restrained, separation and breakage from the outer cylinder of the honeycomb structure can be prevented, and the stability is good and the reliability is sufficient.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a flat foil and a corrugated foil according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a honeycomb structure according to the first embodiment.

FIG. 3 is a longitudinal sectional view showing a metal carrier catalytic converter according to the first embodiment.

FIG. 4 is a perspective view showing a flat foil and a corrugated foil according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing a honeycomb structure according to a second embodiment.

FIG. 6 is a longitudinal sectional view showing a metal carrier catalytic converter according to a second embodiment.

FIGS. 7A, 7B and 7C are longitudinal sectional views showing a conventional metal carrier catalytic converter.

[Explanation of symbols]

12: flat foil, 13: corrugated foil, 20, 21: honeycomb structure,
22 cells, 23 and 24 concave parts, 30 outer cylinders, 31 convex parts.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G091 AA02 AB01 BA10 BA39 GA08 GA14 GB01X GB01Z GB05W GB06W GB07W HA27 HA28 HA31 4G069 AA01 AA08 CA03 EA21 EA24

Claims (2)

[Claims] In a metal carrier catalytic converter in which a honeycomb structure is inserted into an outer cylinder and fixed to each other, at least a part of the outer periphery of both ends of the outer cylinder is depressed on the outer periphery of the honeycomb structure, and the outer cylinder and the honeycomb are formed. Fix the structure and
A metal carrier catalytic converter, wherein an axial gap is provided between the depressed portion of the outer cylinder and the honeycomb structure. 2. The metal carrier catalytic converter according to claim 1, wherein a concave portion is provided in advance on the outer periphery of the honeycomb structure, and a part of the outer cylinder is depressed in the concave portion.