JPH02273545A - Thermal fatigue-resistant metal support for automotive catalyst and its preparation - Google Patents

Abstract

PURPOSE:To absorb thermal stress caused by temperature difference in a honeycomb part and to obtain a catalyst which is not broken by thermal fatigue by shaping a wavy foil to be a wavy shape having bending parts. CONSTITUTION:A bending part B is formed between joining points A and C of platy foils 1, 3 and a wavy foil 2. A bending part D bent in the opposite direction of the part B is formed between the joining point C and neighboring joining point E and thus a nonsymmetrical trapezoidal shape is formed by repeating formation of bending parts in this way. The length A-B-C of the wavy foil is made sufficiently long against the distance between the joining points A, C. With this structure, a catalyst having enough durability to high temperature and high speed exhaust gas flow and high resistance to thermal fatigue even when temperature difference is caused between a honeycomb part and an outer cylinder is obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to metal substrates for automotive catalysts.

[Prior Art] More than 10 years have passed since automobile exhaust gas regulations were implemented, and current exhaust gas countermeasures are taken by improving engines and purifying exhaust gas using catalysts. The catalyst for exhaust gas purification is placed on a ceramic honeycomb such as cordierite.
The mainstream is one having a structure in which γ-alumina powder supporting a noble metal catalyst such as T is supported. However, these ceramic honeycombs have somewhat high exhaust resistance, and the temperature at which they can be used is rather low due to the heat resistance of the buffer stainless steel mesh that is inserted between the honeycomb and the outer cylinder to prevent it from breaking. There were drawbacks such as restrictions.

In recent years, metal carriers made of stainless steel foil have attracted attention as a means of improving these drawbacks. These metal carriers are naturally required to have heat resistance to withstand high temperature and high velocity exhaust gas during the reaction and thermal fatigue resistance to withstand intense heating and cooling. Fourth
As shown in the figure, the metal carrier is generally a stainless steel flat foil 10 with a thickness of about 50 ua+ and a stainless steel corrugated foil 9 with a corrugated edge.
``Cylinder jf knob I, - is cut into an oval rod shape ``: cam body 8, 4-t is inserted into the heat-resistant stainless steel outer cylinder 7, and the lower flat foil - corrugated foil -4 cylinders are joined to the phase Ti by brazing, doweling, etc.

In order to withstand high temperature and high speed exhaust gas, stainless steel foil with good oxidation resistance is used to increase the bonding area of flat foil, corrugated foil, and outer cylinder phase. However, when the temperature is -Mo, t1 is 0, it cannot withstand intense heating and cooling. In other words, it is attached to an automatic kitchen knife 21
In the 4F1 model of the K upper class, when the J engine starts and the running starts, the Lm honeycomb fJ part heats up before the outer cylinder, and it is noted that the engine brake is on for a long time on long downhill slopes.
2. In the case of the type that supplies fuel between two times, the honeycomb or outer cylinder is cooled in advance.

Inside and outside of the cam (V between the cylinder and the honeycomb part)
A large temperature difference will occur. Moreover, due to the temperature difference of 111 during heating and cooling, thermal fatigue failure occurs in the part of the honeycomb near the cylinder, and the honeycomb flies out in the wind direction due to the pressure of air gas. Problems such as ゛ occur.

Japanese Patent Application Laid-Open No. 1983-830'14, a patent application published in 1983-830'14, describes optical technology to prevent such heat ray damage and 1.2 to partially contact the metal foils or the outer cylinder. , as disclosed in XT Public Bulletin No. 3312944, the production F rod becomes complicated 1':] While the strike also increases, the effect %〉-7-
Minute (1 or 8 "j'; no.

[Problems to be Solved by the Invention] The present invention has been proposed in view of the drawbacks of the prior art as described above.

The present invention also proposes a metal substrate that has a thermal fatigue resistance of 41 and is resistant to rapid heating and cooling.

"T step to solve the problem" In order to achieve this goal (1), the present invention is designed to prevent thermal fatigue even when a temperature difference of 6 degrees occurs between the inner side of the honeycomb and between the honeycomb part and the outer cylinder. The shape of the corrugated foil was invented, and the shape of the corrugated foil made it possible to alleviate the thermal stress caused by temperature differences (...) by the shape of the corrugated foil. A metal base for automatic catalysts consisting of a corrugated metal foil (hereinafter referred to as corrugated foil) (hereinafter referred to as corrugated foil) 4, a metal outer cylinder that surrounds a metal outer tube, a cam, etc. A wave shape (hereinafter referred to as a 1-symmetrical trapezoid) in which bent parts with different directions are arranged (cross η rainbow bending between the contact points with the P-foil) 15.
1. In the direction perpendicular to the gas flow. The thermal strain caused by this can be absorbed by making the angle of the bending point formed in the corrugated foil narrower. It is possible to reduce the thermal stress at the 1,1 point core;
It became J-Noh.

＼1) k：K9 Akina et al. Cold-rolled and 2-rolled metal foil at a pressure rate of 50% or more, or corrugated the metal foil, or in the forming direction of the foil. 1-10k in the opposite direction
g/wlI [12 no Zhang) J 1] 1j dog wave (・t
It is also clear that by using JJln-Ix, it is possible to easily manufacture corrugated foil in which J1χ in 1 has a trapezoidal shape of 4r. Part 1 of the above-mentioned support for automatic catalysts
Industrial production has become less efficient.

1] Next, a detailed explanation of the present invention will be given. Fig. 1 shows a cross-section of a 11" corrugated foil and a flat foil stacked together to form an asymmetrical trapezoidal wave shape of the present invention. In general, a flow of 1"L in a metal substrate is shown. 1. If the honeycomb part is heated or cooled due to air scum, '≦i, the middle eastern part of the gas flow and the outside, especially the outer cylinder part.
The temperature difference at the exhaust gas flow increases, causing thermal strain in the plane angle direction with respect to the exhaust gas flow, that is, in the direction of the arrow in Figure 1. In the present invention, in order to absorb this thermal strain, as shown in FIG.
, and between the clear junction points C and E, a bend point bent in the direction of the J5i horn is formed, and a symmetrical trapezoidal wave shape is formed by repeating this process. . Above, due to the change in the angle at the bend point, that is, the change in the wave shape, a wave is generated in the direction of the arrow 1. It is possible to absorb thermal strain of 5.

In order to effectively absorb thermal strain and ensure thermal fatigue resistance, the length ABC of the corrugated foil needs to be 1 minute longer than ν between the junction A and the junction Co1, with respect to l7.2. . Actually j (is ABC
The length of the AC is longer than the length of the AC, -4"'1."<
(i.e., 1805 times or more) - preferably longer, or 1. −・
(・Angle F between foil 1 and corrugated foil BC, and 'I' 7i
3 and wave 71I) The angle G between h゛ should be 5' or more. -F If the angle is small, the wave shape will change due to the heat 53. In the case 1', the corrugated foil will come into contact with the flat foil, making it impossible to ensure sufficient thermal fatigue resistance. Also, between the crests of the waves, the bending direction is alternately changed as shown in B and D above to make the shape of the space surrounded by the corrugated foil and the flat foil into which the gas flows uniform, and to make the gas flow uniform. This is for the purpose of

Brazing, resistance welding, laser welding, electron beam welding, arc welding, diffusion bonding, etc. are used to join flat foil and corrugated foil, but it is desirable that the joining area be small. When the brazing filler metal, arc, etc. spread and the bonding area becomes larger, the movement of the corrugated foil is restricted and the effect of absorbing thermal strain is reduced. Further, in the present invention, it is not necessary to join the flat foil and the corrugated foil at all contact points.

Next, in order to process the above-mentioned asymmetric trapezoidal corrugation having heat fatigue resistance, it is most common to use a corrugation roll. First of all, if a metal foil 5 produced by cold rolling is used at a reduction rate of 50% or more, it can be processed into an asymmetrical trapezoidal wave shape using a trapezoidal wave roll 4 as shown in FIG. It is. In other words, the metal foil is work-hardened by cold rolling, and due to the spring-back phenomenon immediately after the corrugation, the metal foil is not processed into the same trapezoidal wave shape as the roll, and the asymmetrical trapezoidal wave shape shown in Figure 1. Processed into shape. This is advantageous because conventional corrugation processing equipment can be used as is. Second, when corrugating metal foil that has not been hardened as described above, applying tension of 1-10 kg/llm2 to the metal foil to be processed can also process it into an asymmetrical trapezoidal wave shape using a trapezoidal wave roll. It is possible to do so. This is because, as shown in Figure 3, the processing conditions are different at the front and back of the wave due to the tension in the direction of the arrow, and the rear part of the wave that is processed under more tension is bent more, resulting in an asymmetrical trapezoid shape. It becomes a wave shape. By using either of the above two methods, it is possible to process the foil into an asymmetrical trapezoidal wave shape using a trapezoidal wave roll, and it is possible to easily produce a corrugated foil for a metal carrier having thermal fatigue resistance. If the above two methods are not used, the material will have the same symmetrical trapezoidal wave shape as the roll, as shown in FIG. 5, for example, and will not exhibit thermal fatigue resistance.

[Example] Example-1 204kCr-5! kA4 0.4a+-thickness, 100
A stainless steel plate having a width of m+- was cold rolled to a thickness of 50 μm, and corrugated using a trapezoidal corrugated roll shown in FIG. This corrugated foil and a flat foil made of the same material that was not corrugated were layered and wound 36 times to form a honeycomb, and then on the outside was a ferritic foil with an inner diameter of 100+sm, a thickness of 1.5gIm, and a length of lOt)am. Surrounded by a stainless steel outer cylinder.

FIG. 1 shows one embodiment of the present invention, showing a configuration in which a flat foil and a corrugated foil of the metal carrier produced as described above are stacked.

The wave shape shows an asymmetric trapezoid, and the angles of F and G are 10
°, the lengths of ABC and CDH were all 1.1 times the lengths of AC and CE. The flat foil and the corrugated foil were joined together, and the honeycomb part and the outer cylinder were joined together by brazing using Ni-based brazing. As a comparative example, a metal foil of the same material and size was annealed and softened, and then corrugated using the same trapezoidal corrugated roll. Thereafter, a metal carrier was produced in the same manner as above. FIG. 5 shows a configuration in which flat foil and corrugated foil of this comparative example are stacked.

After baking the γ-alumina powder with platinum catalyst supported on the above two types of metal carriers, it was installed in an engine with an exhaust N2000cc, and a bench test was conducted at 800℃ or higher for 1 minute.
The thermal test was repeated for 1 minute at 150° C. or lower for a total of 1 cycle of 15 minutes.

As a result, in the comparative example, after 100 cycles, the diameter of the metal honeycomb part contracted by the angle I, one of the first to third layer honeycombs from the outermost periphery was broken over the entire circumference, and the honeycombs on the inner periphery were broken due to exhaust gas. On the other hand, in the case of the present invention (Fig. 1), no abnormality was observed even after 1200 cycles of heating and cooling.

Example-2 A metal foil made of the same material and size as in Example-1 was annealed and softened, and a tension of 3 kg/1 trta2 was added to it, and corrugated processing was performed using the same trapezoidal corrugated roll as above. . FIG. 3 shows the form of corrugated processing. Examples from the corrugated foil and flat foil produced in this way! The metal support was constructed in the same manner as described above. However, resistance welding was used to connect the flat foil to the corrugated foil and the honeycomb part to the outer cylinder. Furthermore, the γ-alumina powder supported on the platinum catalyst was baked.

Then, I was installed on an engine with an exhaust of 12,000 cc, and a bench test showed 8 (1 minute at V above 10 degrees Celsius, 1 at V above 150 degrees Celsius).
A thermal test was conducted for 5 minutes and 11 cycles.

As a result, no abnormality was observed in the carrier even after 1200 cycles of cooling and heating.

[Effects of the Invention] As explained below, in the present invention, the corrugated foil is made into a wave shape (asymmetrical trapezoidal wave) with a bent portion of 4T. automatic jtj that can absorb heat and not cause damage due to thermal fatigue.
A metal carrier for catalysts has been realized.

4. Drawings @ Il, fax Explanation Fig. 1 shows a cross-section of a corrugated foil and a flat foil overlapped according to the present invention. Second
The figure shows a situation in which cold-rolled metal foil is processed into a °C asymmetric trapezoidal wave shape. Figure 3 shows the situation in which tension is applied to the metal foil and it is processed into a non-symmetrical trapezoidal wave shape.

Figure 1g4 shows the MI# structure of a general metal support. Figure 5 shows the conventional wave-shaped wavy foil Doheihaku? Showing the vertical cross section'1
-0 1.3.1111. 1+, +a・=r foil, 2.9
, l 2 ・= trli foil, 4... trapezoidal waveform V1-
Le, 5... work hardening/, bimetallic foil, 6... addition],
Metal foil that has not been cured 1, 7... Outer cylinder 78... Honeycomb part, A, C, E... Junction point of flat foil and corrugated foil, B, D
... bending part, E, F ... joint part, hciro (
′−Contact angle between foil and corrugated foil.

Claims (1)

[Scope of Claims] 1. In a metal substrate for an autocatalyst consisting of a metal honeycomb formed by overlapping and rolling together a flat metal foil (flat foil) and a corrugated metal foil (corrugated foil) and a metal outer cylinder surrounding them. An automobile catalyst metal carrier characterized in that bent portions having different bending directions are provided alternately between the crests of the waves of the corrugated foil. 2. The method for producing a metal carrier for an automobile catalyst according to claim 1, wherein the corrugated foil is produced by corrugating a metal foil produced by cold rolling 50% or more. 3. The autocatalyst according to claim 1, characterized in that when the corrugated foil is produced using a corrugated roll, a tension of 1 to 10 kg/mm^2 is applied to the metal foil in a direction opposite to the roll forming direction. Method for producing metal carrier for use.