JPH06182221A - Catalyst for purification of exhaust gas and base material for the same - Google Patents

Abstract

PURPOSE:To obtain a catalyst base material for purification of exhaust gas which can be supplied at a low cost by forming hooks on a metal thin plate such as a ferrite-base heat-resistant stainless steel and winding the plate into a spiral to form it a specified dimension. CONSTITUTION:This catalyst material for purification of exhaust gas is produced from a plate material having hooks 2 on the one surface of a metal thin plate 1. This metal thin plate 1 is wound into a spiral to obtain the catalyst of specified dimension for purification of exhaust gas. The metal thin plate 1 consists of a ferrite-based heat-resistant stainless thin plate such as Fe-20wt.% stainless, Cr-5wt.%, and Al-system stainless. Hooks 2 are formed by cutting the metal thin plate 1 along several cutting lines C which cross at one point one another by using a proper die, and pushing the area around the cross point of the thin plate from one side to the other, Thereby, the catalyst material can be easily produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for purifying exhaust gas from an internal combustion engine used in automobiles and the like, and more particularly to a catalyst for purifying exhaust gas using a metal carrier.

[0002]

2. Description of the Related Art In recent years, particularly the problem of air pollution caused by exhaust gas from automobiles has been highlighted, and the demand for purification catalysts has become more severe. Therefore, it is intended to change the conventional catalysts using a ceramic carrier to those using a metal carrier having more excellent purification performance. The material of this metal carrier is Fe-20wt
There are ferritic heat-resistant stainless steels including% Cr-5wt% Al stainless steels.

This heat-resistant stainless steel plate is generally formed in a honeycomb structure and is used by being interposed in an exhaust system of an engine. However, in a state where the engine is just started and the catalyst is cold, that is, a so-called “cold start”, the catalyst of the metal carrier is not activated, and it is impossible to achieve a sufficient purification action.

As means for increasing the efficiency of the catalyst in this cold start, a means for applying an electric current to a metal carrier to preheat the catalyst to start the engine in a state where the activation of the catalyst is enhanced, and a flat plate portion having a honeycomb structure are finely divided. By forming a new honeycomb structure such as a corrugated shape or a flat plate instead of a corrugated plate, the catalyst temperature rise speed due to exhaust gas can be increased, thereby activating the catalyst in a short time. The means etc. which are going to be realized are proposed.

However, in the case of the former means for preheating the catalyst, the purifying action can be sufficiently exerted, but its power consumption is, for example, about 4.5 even in the case of a catalyst for a small passenger car.
It is very large, 5kw. Therefore, it is necessary to separately prepare a battery for catalyst residual heat, which goes against the trend of weight reduction of automobiles. The latter means by changing the honeycomb structure can increase the temperature rising rate of the catalyst to some extent, but for example, the final regulation value of the regulation established in California, USA in October 1990 (per 1 mile running) HC emissions of up to 0.075g)
Is not sufficient to meet.

[0006]

DISCLOSURE OF THE INVENTION The present invention aims to shorten the time required for catalyst activation by forming a new structure different from the conventional honeycomb structure, and to improve the purification rate at cold start. The present invention aims to provide an exhaust gas purifying catalyst and a material thereof.

The present invention also provides an exhaust gas-purifying catalyst material that can be manufactured more easily than conventional catalysts having a honeycomb structure, and thus can be supplied at a lower cost. It is intended to provide a catalyst.

[0008]

The exhaust gas purifying catalyst according to the present invention has a hook formed on a heat-resistant metal thin plate such as ferritic heat-resistant stainless steel, and the metal thin plate having the hook formed is spirally wound. Is formed into a required size and shape. In the exhaust gas purifying catalyst according to the present invention, it is preferable that protrusions having a protrusion length equal to or slightly longer than the protrusion length of the hook are arranged on the thin metal plate on which the hook is formed so as to be appropriately separated.

The exhaust gas purifying catalyst material according to the present invention is formed by forming a hook on a heat resistant metal thin plate such as ferritic heat resistant stainless steel.

[0010]

The hook formed on the thin metal plate projects with respect to the flow of the discharged gas. Therefore, the flow of the exhaust gas is disturbed at the hook position, and while ensuring the time to transfer heat from the exhaust gas to the thin metal plate, the temperature rise at the hook protruding end of the thin metal plate becomes remarkable, which accelerates the catalyst activation. .

Further, the protrusion has a protrusion length equal to or slightly longer than the protrusion length of the hook, so that when the metal thin plate is processed into a spiral shape or a zigzag shape, the adjacent metal thin plate becomes a channel for exhaust gas. The space between the hooks is maintained at a constant interval, and the tips of the hooks are prevented from being deformed particularly by being crushed by the adjacent thin metal plates.

[0012]

EXAMPLE An exhaust gas purifying catalyst material according to an example of the present invention is a metal thin plate 1 as shown in FIGS. 1 (A) and 1 (B).
It is made of a plate-shaped material formed to project the hook 2 on one surface side thereof. The thin metal plate 1 is, as shown in FIG.
By winding in a spiral shape, an exhaust gas purifying catalyst having a required size and shape is formed.

The thin metal plate 1 is Fe-20 wt% Cr-5 wt% A.
It is made of a thin plate of ferritic heat-resistant stainless steel such as l-based stainless steel. As shown in FIG. 1 (B), the hook 2 is formed by a suitable die (not shown) or the like along a plurality of (two in the illustrated case) cutting lines C which intersect each other at one point. Is formed, and the surrounding portion is extruded from one surface of the thin metal plate 1 toward the other surface side around the intersecting point.

The size and shape of the hook 2 and the distance between them are not particularly limited, but generally about 0.5 m.
When forming hooks having a protruding length H of m in a plurality of rows, the distance d between the rows is set to about 2 to 3 mm, and the distance D between the hooks in the row is set to about 4 to 6 mm. The rows of hooks are preferably provided such that they are located between two adjacent hooks of an adjacent row. As a result, as shown in FIG. 2, when formed as a catalyst of a required size and shape by being wound in a spiral shape, an area of about 5 to 13% in the plane direction of the metal thin plate 1 which becomes a flow path of exhaust gas is formed. Therefore, the hook 2 for disturbing the flow of the exhaust gas is projected. However, the scope of the invention is not necessarily limited to these values.

The hook 2 formed in alignment as described above
Among them, the ones at positions separated by an appropriate interval are not the shape of the hook but the protruding curved portion 3 as shown in FIG.
Preferably, it is provided in the shape of. Projection length h of the curved portion 3
Is formed to be equal to or slightly larger than the protruding length H of the hook 2. The spacing between the curved portions 3 may be changed depending on the final size and shape of the catalyst to be produced.
It is sufficient if they are provided at intervals of ~ 80 mm.

The metal thin plates 1 which are overlapped with each other are separated by a hook 2 and a curved portion 3 at regular intervals to form an exhaust gas passage. On the other hand, the hook 2 and the bending portion 3
Are arranged in the shape of an obstacle standing upright in the exhaust gas flow path.

As a result, the exhaust gas passing between the thin metal plates 1 is swirled in its flow and at the same time,
Since it is possible to pass through the hole 4 formed by forming the hook 2 to the other surface side of the thin metal plate 1, a more complicated vortex flow is generated, and the heat from the flowing exhaust gas is absorbed. You can receive it efficiently. Further, in particular, since the protruding end of the hook 2 protrudes as the apex angle portion of the triangle, the efficiency of heat transfer from the exhaust gas in this portion is significantly increased. The curved portion 3 mainly acts to prevent the hooks 2 projecting between the metal thin plates 1 from being crushed between the metal thin plates 1 during the winding process, and to keep the space between the metal thin plates 1 constant. Similarly to the hook 2, it also generates a vortex and receives heat.

Here, the hook 2 is illustrated as projecting in a triangular chevron shape so as to form a circular or polygonal hole in the thin metal plate, but as will be apparent from the above description, after the winding process. Any shape can be applied as long as the exhaust gas flow path is secured between the metal thin plates and at the same time, a protruding portion can be provided in the flow path. For example, as shown in FIG. 4, the square hook 2 may be formed to project.

[0019]

According to the present invention, by forming a hook on a heat-resistant metal thin plate such as ferritic heat-resistant stainless steel, a catalyst material can be prepared very easily, and the metal thin plate on which the hook is formed is formed. Since a catalyst can be created by winding spirally into a desired size and shape,
It is possible to reliably generate a time for effectively generating a vortex in the flow of exhaust gas and receiving heat from the exhaust gas,
Moreover, since the protruding end of the hook is projected alone, it is easily heated, which allows the temperature of the catalyst to be raised more quickly and the time required for activation of the catalyst to be shortened. The efficiency can be improved.

Furthermore, since the protrusion having the protrusion length equal to or slightly longer than the protrusion length of the hook is provided, the hook 2 is surely prevented from being crushed between the thin metal plates 1 during the winding process. In addition, the distance between the metal thin plates 1 can be kept constant.

In addition, since it can be produced by forming a hook or the like on a thin metal plate by pressing and winding the thin metal plate, it can be manufactured very easily and the catalyst can be supplied at low cost.

[Brief description of drawings]

FIG. 1 shows an exhaust gas-purifying catalyst material according to an embodiment of the present invention, (A) showing its cross-sectional shape, (B) a partial view showing its plane shape, among the hooks shown in (B). One of them is shown unprocessed or in the process of being processed for the sake of explanation.

FIG. 2 is a partial cross-sectional view of an exhaust gas purifying catalyst according to an embodiment of the present invention.

FIG. 3 is a view similar to FIG. 3 showing a modified example of a thin metal plate.

FIG. 4 is a view showing a modified example of an exhaust gas-purifying catalyst material formed on a thin metal plate.

[Explanation of symbols]

 1 Metal thin plate 2 Hook 3 Curved part 4 Hole

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location F01N 3/28 301 P

Claims (3)

[Claims] 1. A hook is formed on a heat-resistant metal thin plate such as ferritic heat-resistant stainless steel, and the metal thin plate on which the hook is formed is spirally wound into a required size and shape. Exhaust gas purification catalyst. 2. The thin metal plate on which the hook is formed is provided with projections having a projection length equal to or slightly larger than the projection length of the hook, which are appropriately spaced. Exhaust gas purification catalyst. 3. A catalyst material for exhaust gas purification, characterized in that a hook is formed on a heat resistant metal thin plate such as ferritic heat resistant stainless steel.