JP3309147B2 - Metal carrier for exhaust gas purification catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal carrier for an exhaust gas purifying catalyst which carries an exhaust gas purifying catalyst for an internal combustion engine such as a cogeneration gas engine.

[0002]

2. Description of the Related Art Conventionally, a metal carrier supporting an exhaust gas purifying catalyst of an internal combustion engine has a predetermined width on a peripheral surface of a honeycomb body formed by laminating a flat plate and a corrugated plate and winding the roll on a roll. Generally, the foil is wound around the entire circumference, inserted into an outer cylinder for housing the honeycomb body, and directly bonded to the outer cylinder by vacuum firing. In addition, there has been proposed a structure in which a brazing foil is attached to both sides of a honeycomb body and an outer cylinder via an intermediate cylinder and joined thereto (Japanese Patent Application Laid-Open Nos. 4-222636, 4).
No. 29750). In this manner, the metal carrier is integrally joined to the flat plate and the corrugated plate of the honeycomb body, and the outer cylinder and the honeycomb carrier usually by brazing. A catalyst supporting layer made of alumina or the like is formed on the surface of the honeycomb passage of the honeycomb body of the metal carrier, and a metal catalyst is supported on the catalyst supporting layer to serve as an exhaust gas purification catalyst. And it is installed in the exhaust passage of the internal combustion engine and purifies HC, CO, and NO _X contained in the exhaust gas. In addition, since it is preferable to secure the area of the honeycomb passage as much as possible in a limited volume, the thickness of the flat plate and the corrugated plate is made as thin as possible within a range where the strength can be maintained.

[0003]

By the way, the metal carrier is usually made of a material different from that of the outer cylinder and the honeycomb body, and when the honeycomb body has a small coefficient of thermal expansion and a large coefficient of thermal expansion of the outer cylinder, a brazing material is applied. When the honeycomb body is inserted into the outer cylinder and brazed to the outer cylinder during vacuum firing, the honeycomb body has a diameter of 0.7 to 0.7 mm.
Shrink by about 1.5%. For this reason, a gap is formed between the outer cylinder and the honeycomb body, and reliable joining cannot be performed with the brazing material.

[0004] There is also a method in which a honeycomb body is press-fitted into an outer cylinder or a press fit of the outer cylinder is used to give a compressive force to fit the honeycomb body. However, excessive compression causes wrinkles or the like in the honeycomb cell portion. There are limits to the application of the method. In addition, the exhaust gas passing through the honeycomb body when the metal carrier is used has a larger flow velocity in the center portion than in the outer peripheral portion of the honeycomb body. Therefore, in the metal carrier, due to the contact with the high-temperature exhaust gas, the heat generated by the catalytic reaction, and the heat release from the outer cylinder to the outside air, a temperature distribution occurs in which the temperature is higher at the center and lower at the outer periphery. This temperature distribution causes a difference in the amount of expansion and contraction between the honeycomb body and the outer cylinder, but the expansion and contraction movement in the radial and axial directions of the honeycomb body is regulated by the outer cylinder, and the honeycomb body is constituted. Since the thickness of the flat plate and the corrugated plate is generally much smaller than the thickness of the outer cylinder, thermal stress acts on the honeycomb body. Then, due to the repetition of expansion and contraction, the flat plate and the corrugated sheet near the outer peripheral portion of the honeycomb body are plastically deformed to cause metal fatigue, and eventually the flat plate and the corrugated sheet of the honeycomb body may be broken.

The above problems naturally become more severe as the diameter of the honeycomb body increases, and it is extremely difficult to produce a large metal carrier. The present invention has been made in view of the above circumstances, and ensures the bonding between the honeycomb body and the outer cylinder, and can reliably perform the bonding even with a honeycomb body having a large diameter.
It is another object of the present invention to provide a metal carrier having improved durability of a honeycomb body due to thermal stress.

[0006]

A metal carrier for an exhaust gas purifying catalyst according to the present invention comprises a honeycomb body formed by laminating a flat plate and a corrugated plate and winding the roll into a roll shape, and coaxially around the outer periphery of the honeycomb body. An outer cylinder arranged and holding the honeycomb body, and a plurality of flat joining plates provided in a chord shape on the inner surface side of the outer cylinder and joining and fixing the honeycomb body at a central portion of the chord, And In addition, the honeycomb body is connected to the bonding body.
It is preferable that it is brazed and fixed to the plate.
Good.

[0007]

The metal carrier for an exhaust gas purifying catalyst according to the present invention is formed by joining a honeycomb body on the surfaces of a plurality of joining plates provided in a chord shape on the inner surface of the outer cylinder and disposing the honeycomb body in the outer cylinder. ing. For example, the chord-shaped joining plate presses and joins the honeycomb bodies on a plane to which the brazing foil is adhered.
For this reason, the honeycomb body held at the center of the outer cylinder has no gap between the honeycomb body and the joining plate, and can be securely joined with the brazing foil.

In the conventional metal carrier, the joining between the honeycomb body and the outer cylinder is caused by, for example, the contraction of the honeycomb body held by the outer cylinder at the time of firing after brazing or the thermal expansion coefficient of the outer cylinder portion is higher than that of the honeycomb body. When is large, a gap is generated between the outer cylinder and the honeycomb body, and it is easy to cause poor bonding. If the length of the metal carrier is assumed to be 90 mm, if it is to be wound around the entire circumference of the honeycomb body with a 20 mm brazing foil and inserted into the outer cylinder to be joined, if more than half of the circumferential direction is extreme, it is joined over the entire circumference. Missing parts occur. Even if the joints are not uniform in the circumferential direction, a deviation occurs, and the balance of holding and fixing the metal carrier becomes extremely poor.

On the other hand, in the metal carrier of the present invention,
Since the honeycomb body is joined at the center of the chordal joint plate surface, the honeycomb body is pressed by the joint plate surface, and the contact area becomes large, and gaps at the joint surface are generated even by heating during brazing. And a secure joint surface can be secured. Further, by arranging a plurality of main bonding plates in the circumferential direction of the outer cylinder, it is possible to hold and fix the entire honeycomb body in a well-balanced manner with a small number of bonding surfaces.

Further, in the conventional metal carrier formed by directly joining the honeycomb body to the inner surface of the outer cylinder by brazing, the stress generated by expansion and contraction of the honeycomb body due to the cooling / heating cycle applied during use causes the joining between the honeycomb body and the outer cylinder. Working directly in the department,
Problems such as peeling cracks occur. On the other hand, in the metal carrier of the present invention, the honeycomb body is fixed by attaching a joining plate in a chord shape to the inner surface of the outer cylinder, and only the portion in contact with the inner periphery of the outer cylinder is fixed by welding or the like, and the back side of this joining plate is fixed. (Between the outer cylinder) is not fixed, and this joint plate absorbs stress due to bending etc. against expansion and contraction of the honeycomb body and outer cylinder generated by severe cooling and heating cycles during use It is possible to improve the durability life of the metal carrier. This is because the larger the diameter of the metal carrier, the greater the effect of the presence of the above-mentioned joining plate, and the larger the diameter of the metal support.
When the thermal expansion coefficient of the outer cylinder is larger than that of the honeycomb body, the effect becomes more remarkable.

[0011]

The present invention will be specifically described below with reference to examples. (Embodiment 1) FIG. 1-1 is a perspective view of an outer cylinder 1 provided with a honeycomb body 5 in FIG. 1-2 and FIG. 1-2 is a perspective view of an outer cylinder 1 provided with a bonding plate 2 of the present invention. The principal part explanatory drawing of the joining in the brazing foil 3 is shown.

In this metal carrier, the honeycomb body 5 has an outer cylinder 1
And is fixed in the outer cylinder 1 by brazing with the joining plate 2 joined to the outer cylinder 1. The joining plate 2 is a substantially rectangular plate having a width of 4 to 4 times the outer peripheral length of the honeycomb body 5.
The length of the honeycomb body 5 in the longitudinal direction is 20% to 100% of the length of the outer peripheral side face of the honeycomb body 5.
It is preferable to enhance the bonding property with the metal. If the width of the joining plate 2 is smaller than the above, the joining area is insufficient and a problem occurs in the joining strength, which is not preferable. If the width is too large, the honeycomb body 5 is deformed and fixed, which is not preferable.
Moreover, it is preferable that the total width of the joining plate 2 used is in the range of 8 to 50% of the outer peripheral length of the honeycomb body.

This metal carrier is particularly effective when the honeycomb body 5 has a relatively large diameter of 200 to 750 mm. A plurality of (two to twelve) joining plates 2 are installed at equal intervals in the circumferential direction of the inner surface of the outer cylinder 1, and the positions thereof are within the range of the side surface length of the honeycomb body.
-2, as shown by the position on the side surface of the honeycomb body 5 in FIGS. 3-3 and 3-4, the honeycomb body 5 can be installed at the center, near the gas inlet side, closer to the gas outlet side, and closer to both sides with respect to the gas flow direction. .

The honeycomb body 5 is formed by winding a flat plate and a corrugated plate in a roll shape in a state of being overlapped. The corrugated plate is usually formed by bending a flat plate into a corrugated shape, and has the same material and the same thickness as the normal flat plate. The flat plate and the corrugated plate are formed of, for example, an Al-Cr-Fe alloy, stainless steel, or the like, as in the related art. As described above, it is preferable to secure the area of as many honeycomb passages as possible in a limited volume, so that a relatively thin plate having a thickness of, for example, 0.05 mm is used. This honeycomb body 5
For example, in a state where the brazing material is applied to the top of the corrugated sheet, the corrugated sheet is formed by being wound up in a roll shape on a flat plate and then heated. Thereby, the flat plate and the corrugated plate are brazed and integrally joined. Further, they can be integrated by diffusion bonding of a brazing material.

The outer cylinder 1 may be made of a conventional material such as ferritic stainless steel, for example, and has a plate thickness of about 2 to 4 since the diameter of the honeycomb body 5 is relatively large.
mm is available. Thermal stress is generated due to a temperature difference, a difference in rigidity, a difference in expansion coefficient, or the like between the honeycomb foil and the outer cylinder 1. When the thermal stress is small, the honeycomb body is relaxed by the deformation of the honeycomb body. However, when the temperature becomes high and the thermal stress cannot be relaxed by the deformation, the honeycomb body is broken or broken. However, in the metal carrier of the present invention, the honeycomb bodies are only joined by the joining plate 2, and the degree of freedom of deformation is high.
Further, stress can be absorbed by omitting the joining plate 2.

A chord-shaped gap between the joining plate 2 and the outer cylinder 1 is fixed to the honeycomb body by brazing so that a corrugated plate 6 is inserted and does not come off as shown in FIG. In the same manner as described above, the catalyst is supported, the gas entering and leaving the gap are fixed by welding such as by pressing the both sides of the gas with the plate 7 as shown in FIG. 4-1 or the gap is covered with a ring over the entire circumference. May be. As a result, the problem of exhaust gas leakage can be solved. (Example 2) In this metal carrier, first, a honeycomb body 5 was formed by stacking a flat plate made of a 5Al-20Cr-Fe alloy having a plate thickness of 0.05 mm and a corrugated plate formed by bending the flat plate into a wave shape.
The flat plate was wound in a roll shape with its front side facing to form a cylinder having a diameter of 360 mm and a cylinder height of 120 mm.

The outer cylinder 2 is made of SUS304 stainless steel, has a cylindrical shape with a thickness of 3 mm, an inner diameter of 362 mm, and a height of the cylinder of 155 mm. The joining plate 2 is made of SU
70mm × 50mm × 1.5 with stainless steel of S304
1 mm by welding on both sides 4
Were joined at equal intervals to the inner peripheral surface near the gas exit side. A brazing foil 3 having a thickness of 30 μm was attached to the surface of the joining plate 2 by spot welding or the like. And the above honeycomb body 5
Is inserted and the wax powder is spread and applied inside the honeycomb body, and baked in vacuum (1200 ° C., degree of vacuum 5 × 10 ⁻⁴ Torr for 2 hours)
As a result, the joining plate 2 was joined to the honeycomb body 5 and the honeycomb body 5 itself.

The honeycomb body 5 is brazed while being pressed through the brazing foil 3 formed on the surface of the joining plate 2 joined to the outer cylinder 1, so that the honeycomb body 5 is connected to the joining plate 2. It can be securely bonded on two surfaces. In the metal carrier configured as described above, the contraction rate of the diameter of the honeycomb body 1 was 0.88%, and 90% of the metal carriers were bonded on the bonding surface of the bonding plate. (Comparative Example 1) In Example 2, the outer cylinder was changed to an inner diameter of 360 mm.
Without using a joining plate, a brazing foil was attached to the entire periphery of the outer peripheral surface of the honeycomb body on the gas exit side, with a width of 20 mm and a thickness of 50 μm. This honeycomb body was inserted into an outer cylinder and joined under the same conditions as in the example.

In the metal carrier thus configured, the contraction rate of the diameter of the honeycomb body 1 was 0.91%, and the bonding was not performed over the entire circumference. (Example 3) A metal carrier in the case of a honeycomb body having a larger diameter than that of Example 2. The material of the honeycomb body was the same 20Cr-5Al-Fe alloy as in Example 1 and had a diameter of 55.
The height is 0 mm and the height is 90 mm. The outer cylinder is made of SUS430 stainless steel, has an inner diameter of 551 mm, a height of 140 mm, and a thickness of 3 mm.

The joining plate is made of SUS430 stainless steel having a size of 100 mm × 50 mm × 1 mm at the center (3-1) of the inner surface of the outer cylinder and at a position equally divided into six equal parts of the inner circumference of the outer cylinder. Were joined. A brazing foil having a thickness of 50 μm was affixed to the joining plate surface. The joining was performed by brazing by vacuum firing under the same conditions as in Example 2.

The obtained metal carrier has a honeycomb body with a diameter shrinkage of 0.95% and a 95%
Had joined. (Comparative Example 2) Using the same honeycomb body and outer cylinder as in Example 3,
20mm width at the center of honeycomb body without using joining plate
A brazing foil having a thickness of 50 mm and a thickness of 50 mm was adhered and joined under the same conditions as in Example 3. In the obtained metal carrier, the contraction rate of the diameter of the honeycomb body was 0.82%, 50% of the entire periphery was not joined, and the non-joined portion was continuous over half the periphery.

[0022]

According to the present invention, there is provided a metal carrier in which a bonding plate is interposed between a honeycomb body and an outer cylinder, and the honeycomb body is bonded to the plate surface at the bonding plate surface. Since the joining plate surfaces are joined while pressing the honeycomb body, 90% or more of the joining surfaces are joined. Therefore,
The honeycomb body is a metal carrier which is joined to the outer cylinder and has excellent durability without peeling or deformation. This characteristic can be exhibited particularly in a metal carrier having a large diameter.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a relationship between a honeycomb body, an outer cylinder, and a joining plate. FIG.
2 is a perspective view of the outer cylinder in which the joining plate is joined inside.

FIG. 2 is an explanatory schematic diagram showing a state in which a honeycomb body is joined to an outer cylinder via a joining plate.

FIG. 3 is an explanatory schematic diagram illustrating a joining position of the joining plate at the outer cylinder. 3-1 is the center, 3-2
Is the inlet side, 3-3 is both the inlet side and the outlet side,
Numeral 4 shows an example in which it is arranged at a position on the gas outlet side.

FIG. 4 is an example in which a gap between a joining plate and an outer cylinder is prevented, in which 4-1 is closed by a plate, and 4-2 is a corrugated plate fixed to support a catalyst carrier similarly to a honeycomb body. This is an example of carrying.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B01J 21/00-38/74 B01D 53/86 B01D 53/94 F01N 3/28

Claims (2)

(57) [Claims] 1. A honeycomb body formed by laminating a flat plate and a corrugated plate and winding them in a roll shape, an outer cylinder coaxially arranged on an outer periphery of the honeycomb body and holding the honeycomb body, A metal carrier for an exhaust gas purifying catalyst, comprising: a plurality of flat joining plates provided on an inner surface side in a chord shape and joined and fixed to the honeycomb body at a central portion of the chord. 2. The filter according to claim 1, wherein the honeycomb body is attached to the joining plate.
The exhaust according to claim 1, which is brazed and fixedly joined.
Metal carrier for gas purification catalyst.