JP2729041B2 - Metal substrate for automotive exhaust gas purification catalyst with excellent thermal fatigue resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement in a metal substrate (metal carrier) used as a catalytic converter for purifying exhaust gas from automobiles.

[0002]

2. Description of the Related Art In recent years, as a carrier for supporting a catalyst for purifying an exhaust gas of an automobile, a metal carrier has been attracting attention instead of a ceramic honeycomb. This metal carrier has a thickness of 50
A flat stainless steel foil of about μm (hereinafter simply referred to as flat foil) and a corrugated stainless steel foil (hereinafter simply referred to as corrugated foil) are laminated to form a cylindrical or elliptical cylinder. The honeycomb body is wound into a honeycomb body, the honeycomb body is fitted in a metal outer cylinder, and the flat foil, corrugated foil, and outer cylinder are joined to each other by brazing, resistance welding, or the like.

[0003] Metal carriers are required to have sufficient strength to withstand high-speed continuous operation of automobiles and to withstand thermal fatigue resistance to withstand severe heating and cooling cycles. In particular, a honeycomb body composed of a metal outer cylinder and a flat foil and a corrugated foil fitted therein has a heat distortion due to a temperature difference caused by rapid heating and cooling (the honeycomb body is heated prior to the metal outer cylinder). The metal carrier is required to have a high heat-resistant fatigue property from the point that this causes the joint part of both to be broken and causes the honeycomb body to jump out or to be displaced in the downstream direction of the exhaust gas. You.

[0004] Technical means aimed at strengthening the joining between the metal outer cylinder and the honeycomb body include, for example, Japanese Patent Application Laid-Open Nos. 61-19957 and 62-453.
As disclosed in Japanese Patent No. 45, there is a technique for improving the thermal fatigue strength of a metal carrier by partially joining a honeycomb body itself. For the purpose of preventing peeling at the joint between the metal outer cylinder and the honeycomb body, for example, Japanese Utility Model Application Laid-Open No.
There is a technique disclosed in 194436. This technique joins the corrugated foil and the flat foil to each other in at least a part of the cross section of the honeycomb body, and joins the outer periphery of the honeycomb body to the inner peripheral surface of the metal outer cylinder only in one cross section of the metal outer cylinder. In addition, thermal distortion is absorbed in the axial direction to prevent separation at the joint between the metal outer cylinder and the honeycomb body.

Japanese Patent Application Laid-Open No. Sho 62-30533 discloses that a collar-shaped spacing piece is inserted between a honeycomb body and a metal outer cylinder so as to protrude in the exhaust gas upstream direction, and the temperature between the honeycomb body and the metal outer cylinder is increased. Japanese Patent Laid-Open Publication No. Sho 63-28822 discloses a technique for absorbing thermal strain caused by a difference between a honeycomb body and a metal outer cylinder. There is disclosed a technique in which an intermediate cylinder having a protruding portion (projecting toward the exhaust gas upstream direction) is fitted to absorb thermal strain caused by a temperature difference between a honeycomb body and a metal outer cylinder.

However, in these prior arts,
In the case of partially joining the honeycomb body itself, it is difficult to manufacture a metal carrier, and it is difficult to always stably obtain a large number of carriers having a constant joining structure. In addition, the one that joins the metal outer cylinder and the honeycomb body in one cross section is effective in reducing the thermal stress in the axial direction, but because the thermal stress in the radial direction cannot be relaxed, the diameter is larger than the length. There is a problem with these carriers. Furthermore, the technique of fitting an intermediate cylinder having a collar or a large number of fin-shaped protrusions between the honeycomb body and the metal outer cylinder is an effective technique for effectively relieving thermal stress, but it makes a round of the carrier. The collar-shaped spacing piece has high rigidity itself due to its shape, and it is difficult to reduce thermal stress in the radial direction of the carrier.

On the other hand, as disclosed in Japanese Utility Model Laid-Open Publication No. Sho 63-28822, an intermediate cylinder having a large number of fin-like projections is fitted therein so that it is not joined to a metal outer cylinder. When the tip of the fin-shaped portion protruding in the axial direction of the carrier is joined to the inner peripheral surface of the metal outer cylinder, the fin-shaped projection matches the curvature of the inner peripheral surface of the metal outer cylinder. The curvature must be given, and the processing is extremely difficult.

[0008]

SUMMARY OF THE INVENTION The present invention solves the problems in the prior art in particular when fitting an intermediate cylinder having a fin-like protrusion, and effectively absorbs the above-mentioned thermal strain. It is an object of the present invention to provide a metal carrier (metal substrate) for an automobile exhaust gas purifying catalyst which can further strengthen the joining between a metal outer cylinder and a honeycomb body and withstand long-term use.

[0009]

The gist of the present invention is to provide a honeycomb body formed by superimposing and winding a flat metal foil and a corrugated metal foil, and fitting the honeycomb body. A metal outer cylinder, and a metal substrate for an automobile exhaust gas purifying catalyst, wherein a stainless steel intermediate cylinder provided with a plurality of fin-shaped protrusions on its outer peripheral surface is fitted between the honeycomb body and the metal outer cylinder. The fin-shaped protrusion of the intermediate cylinder extends in the circumferential direction or the oblique direction of the intermediate cylinder, and a straight line connecting two notch tips of the fin-shaped protrusion and the intermediate cylinder is substantially parallel to the axial direction of the intermediate cylinder. An automobile having excellent heat fatigue resistance, wherein a tip of a fin-shaped protrusion of the intermediate cylinder is joined to an inner peripheral surface of a metal outer cylinder, and an inner peripheral surface of the intermediate cylinder is joined to an outer peripheral surface of the honeycomb body. Metal substrate for exhaust gas purification catalyst.

Hereinafter, the present invention will be described in detail. In the present invention, an intermediate cylinder exists between the metal outer cylinder and the honeycomb body, and a fin-shaped protrusion is provided in a circumferential direction or an oblique direction of the intermediate cylinder, and the fin-shaped protrusion and the intermediate cylinder are provided. The straight line connecting the two notch tips is almost parallel to the axial direction of the intermediate cylinder, the fin-shaped protrusion is joined to the metal outer cylinder, and the inner peripheral surface of the intermediate cylinder is joined to the honeycomb body, so when using it Even if a thermal strain due to a difference in thermal expansion occurs, the intermediate cylinder, particularly the entire fin-shaped protrusion that protrudes in the circumferential or oblique direction of the carrier, shares and absorbs the thermal strain. This prevents separation at the joint between the metal outer cylinder and the honeycomb body.

On the other hand, in the prior art disclosed in Japanese Utility Model Laid-Open Publication No. Sho 63-28822, a metal outer cylinder and a honeycomb body are required to be more robust and to withstand long-term use, as in the object of the present invention. The inventors of the present invention have found that, when joints are made, the thermal strain is concentrated at the root of the fin-shaped protrusion, and the root of the fin-shaped protrusion is broken by fatigue during the durability test with the engine and cut off. This is because the cut-out fin-shaped protrusion having a curvature in the circumferential direction has a high rigidity in the radial direction of the intermediate cylinder, and when the length of the fin is short, the fin does not bend when it is bent in the radial direction. Because it turns at the root. On the other hand, as in the present invention, the direction of the fin is set to the circumferential direction or the oblique direction, and the straight line connecting the two notch tips of the fin-shaped protrusion and the intermediate cylinder is substantially parallel to the axial direction of the intermediate cylinder. Then, since the entire fin is bent with respect to the bending in the radial direction, the strain is dispersed throughout the fin, so that the fin can be used for a long time.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on preferred embodiments with reference to the drawings. FIG. 1 shows a metal carrier according to the present invention. In the present invention, as the intermediate cylinder 3 fitted between the metal outer cylinder 2 and the honeycomb body 1, an intermediate cylinder made of, for example, stainless steel having a plurality of fin-shaped protrusions 4 provided on its outer periphery is used as a component. . FIG. 2 shows the protruding direction of the fin-shaped protrusion 4.

The fin-shaped protrusions 4 are preferably formed by making a U-shaped cut in the intermediate cylinder itself (for example, it can be made by punching) and raising it outward. May be attached. The joint between the fin-shaped protrusion 4 and the inner peripheral surface of the metal outer cylinder 2 is performed at a part of the tip of the fin-shaped protrusion 4 (shaded portion), and the base side of the fin-shaped protrusion 4 is left unjoined. is required. Further, the joining with the honeycomb body 1 is performed on a part or the whole of the inner peripheral surface of the intermediate cylinder in the circumferential direction.

The fin-shaped protrusion 4 shown in FIG.
Is an example in which the center line (which can be said to be the direction in which the largest heat strain is absorbed) protrudes in a direction perpendicular to the axial direction of the intermediate cylinder. is there. The fin-shaped protrusion 4 shown in FIG. 2B is formed obliquely downstream of the exhaust gas flow, and the fin-shaped protrusion 4 shown in FIG. 2C is formed diagonally upstream of the exhaust gas flow. It is an example. In each case, the straight line (dotted line in FIGS. 1 and 2) connecting the two notch tips of the fin-shaped protrusion and the intermediate cylinder is substantially parallel to the axial direction of the intermediate cylinder.

According to the present invention, as described above, the intermediate cylinder 3 is interposed between the metal outer cylinder 2 and the honeycomb body 1 to indirectly join the metal outer cylinder 2 and the honeycomb body 1 together with the intermediate cylinder. Since the fin-shaped protrusion 4 is provided on the cylinder and a part thereof is joined to the inner peripheral surface of the metal outer cylinder, it has sufficient strength to withstand high-speed continuous operation, and rapid heating and cooling when using the carrier. Even if thermal expansion occurs due to a difference in thermal expansion between the metal outer cylinder 2 and the honeycomb body 1 caused by the cycle, thermal distortion can be absorbed by the non-joined portions of the fin-shaped protrusions 4. Metal outer cylinder 2
Even if the thermal strain caused by the difference in thermal expansion between the honeycomb body 1 and the honeycomb body 1 is in the axial direction or the radial direction, it can be absorbed.

[0016]

【Example】

(Example 1) Test carrier (example in which FIG. 2 (c) is provided as a protruding portion) Honeycomb body: A stainless steel foil of 20% Cr-5% Al having a thickness of 50 μm and a flat foil were formed by winding 36 rolls. Outer cylinder: made of stainless steel with an inner diameter of 100 mm, a thickness of 1.5 mm, and a length of 100 mm. Intermediate cylinder: A stainless steel cylinder with an inner diameter of 100 mm, a thickness of 0.3 mm, and a length of 100 mm, 15 mm h × 10 mm l × 10
15 fin-shaped protrusions of mm w (see FIG. 2 (c)) were formed in the circumferential direction and in four rows in the axial direction (total 60). Carrier bonding conditions The intermediate body was brazed with a honeycomb body and a Ni brazing material over the entire circumference at a central part width of 40 mm on the inner surface, and brazed with a Ni brazing material on the inner surface of the outer cylinder in a region of 5 mm × 10 mm width of the tip of the fin-shaped protrusion. Then, γ-alumina supporting a Pt catalyst is baked. Test conditions The above carrier was mounted on an engine with a displacement of 2000 cc, and a bench test was performed at 800 ° C or higher for 1 minute and 150 ° C or lower for 1 minute.
, A total of 15 minutes of cooling and heating tests were performed. As a comparative example, a carrier in which the outer cylinder and the honeycomb body were directly bonded without interposing the intermediate cylinder was tested under the same conditions as above. Test Results No abnormalities were observed in this substrate even after 1200 cycles of cooling and heating.

[0017]

As described above, according to the metal substrate of the present invention, all the cushioning members are provided at the joint between the outer cylinder and the honeycomb body, which may be peeled off due to the difference in thermal expansion due to a severe cooling / heating cycle. Since the intermediate which absorbs the thermal strain in the direction is interposed, the peeling of the joint and the breakage of the honeycomb body can be effectively prevented even under the above severe conditions.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a metal base according to the present invention.

FIG. 2 is an explanatory view showing various forms of a fin-shaped protrusion showing another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 honeycomb body 2 outer cylinder 3 intermediate cylinder 4 fin-shaped protrusion

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location B01J 35/04 321 B01J 35/04 321A ZAB ZAB (72) Inventor Masayuki Amato Fuchinobe, Sagamihara City, Kanagawa Prefecture 5-10-1 Nippon Steel Corporation 2nd Technology Research Laboratory (72) Inventor Yutaka Satano 1 Kimitsu, Kimitsu City, Chiba Prefecture Inside Kimitsu Works, Nippon Steel Corporation (72) Inventor Toshikazu Nakagawa Aichi Nagoya Works, Nippon Steel Corporation, Tokai-cho, Tokai City, Japan (72) Inventor Yoshio Nishizawa 3-3-1 Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kinzoku Co., Ltd. (72) Inventor Akihiko Kasahara Tokyo 4-10-1 Funatari, Itabashi-ku The Nippon Research Institute, Inc. (56) References Japanese Utility Model 1988-1988 (JP, U) Japanese Utility Model 1987-84611 (JP, U) Akira 62-45327 (JP, U) Tokuoyake flat 1-54090 (JP, B2)

Claims (1)

(57) [Claims] 1. A honeycomb body formed by superimposing and winding a flat metal foil and a corrugated metal foil, a metal outer cylinder on which the honeycomb body is fitted, and the honeycomb body and the metal outer cylinder In the metal base for an automobile exhaust gas purifying catalyst, in which a stainless steel intermediate cylinder provided with a plurality of fin-shaped projections on its outer peripheral surface is fitted, the fin-shaped projections of the intermediate cylinder are arranged around the periphery of the intermediate cylinder. The straight line connecting the two notch tips of the fin-shaped protrusion and the intermediate cylinder is substantially parallel to the axial direction of the intermediate cylinder, and the tip of the fin-shaped projection of the intermediate cylinder and the outside of the metal. A metal substrate for an automobile exhaust gas purifying catalyst having excellent thermal fatigue resistance, wherein an inner peripheral surface of a cylinder is joined and an inner peripheral surface of the intermediate cylinder is joined to an outer peripheral surface of the honeycomb body.