JPH0797920A - Metal catalyst - Google Patents

Abstract

PURPOSE:To provide metal catalyst (catalyst converter) which can prevent telescopic deformation of a metal foil effectively without incurring inconveniences such as rise of exhaust pressure and reduction of exhaust gas purification rate even in the case of metal catalyst of current-carrying heat generation type. CONSTITUTION:In a catalyst converter CS (metal catalyst) of current-carrying heat generation type, a lattice-like member 11 (wire gauze) which is fixed on a shaft member 5 and a converter case 1, is arranged slightly backward of a metal foil 6, and deviation or displacement in the axial direction of each part of the metal foil 6 is prevented by the lattice-like member 11 when force in the axial direction is applied on the metal foil 6 so as to prevent telescopic deformation of the metal foil 6. Here, as the lattice-like member 11 is the wire gauze consisting of thin metal wires, ventilation resistance is reduced and rise of exhaust pressure is prevented. Also, exhaust gas purification rate is increased because exhaust gas does not stagnate on the upstream side of the wire gauze.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal catalyst having a metal foil composed of a metal flat plate and a corrugated plate.

[0002]

2. Description of the Related Art Generally, a catalytic converter for purifying nitrogen oxides, hydrocarbons, etc. in exhaust gas is used in an automobile exhaust system.
(Exhaust gas purifying device) is provided, but in such a catalytic converter, a catalyst in which catalyst particles having a noble metal as a main component are supported on a carrier through an alumina layer is usually the case of a catalytic converter (converter case). Placed inside. Here, as the carrier, a ceramic carrier has been frequently used, but since the ceramic carrier is relatively thick, there is a problem that ventilation resistance becomes large and exhaust pressure of the engine rises.

Therefore, in recent years, thin (for example, thickness 50
A catalytic converter, that is, a metal catalyst in which a catalyst is carried on a metal carrier, that is, a metal foil using a metal plate or a metal foil is becoming popular. Here, the metal foil is formed, for example, by a method of winding a thin flat plate and a corrugated plate made of stainless steel into a substantially columnar shape so that the two plates are alternately laminated. In the metal foil formed by winding the flat plate and the corrugated plate together as described above, it is necessary to fix the flat plate and the corrugated plate so as not to shift in the axial direction. It is performed by brazing or welding the plate and the metal foil at both ends in the axial direction of the metal foil.
(See, for example, Japanese Examined Patent Publication No. 63-44466).

The catalytic converter using such a metal foil has an advantage that the ventilation resistance is small, and also has an advantage that the exhaust gas purification performance is improved because the surface area per unit volume is large. Since it is relatively small, there is also an advantage that the warm-up time after engine start is shortened.

[0005]

However, in a catalytic converter using such a metal foil, an axial force is applied to a cylindrical metal foil due to inertial force due to acceleration / deceleration of an automobile or thermal deformation of the converter case. However, there is a problem in that a telescopic displacement or displacement of the metal foil, that is, a so-called telescopic deformation occurs in the converter case.

By the way, generally, when the engine is cooled after the engine is started, the temperature of the catalyst in the catalytic converter is low, so that the activity thereof is low and the exhaust gas purification rate becomes low during this period. Therefore, a so-called EHC (electric heat converter) is proposed, which is an energization heat generation type catalytic converter in which a metal foil is energized to generate heat when the engine is cold and the catalyst temperature is increased to enhance the exhaust gas purification rate. (For example, the actual exploitation Sho 63-676
09 gazette). In such EHC, a predetermined voltage is applied between the central portion and the peripheral portion of the cylindrical metal foil to energize it. In this case, the flat plate and the corrugated plate are joined by brazing or welding. Then, an electrical short circuit occurs, so that the flat plate and the corrugated plate cannot be joined. Therefore, the EHC has a problem that telescope-like deformation is likely to occur.

Therefore, as shown in, for example, FIGS. 5 and 6, the space 102 in the converter case 101 is joined to the shaft member 103 made of a conductor while the insulator 10 is formed.
Metal foil 1 fixed to the inner surface of the case via 5
04 is arranged and the electrode 1 is provided on the periphery of the metal foil 104.
In the EHC 100 to which 07 is connected, a plate-like member 106 having a central portion fixed to the shaft member 103 and both end portions fixed to the inner peripheral surface of the case is provided on the slightly downstream side (right side in FIG. 5) of the metal foil 104, It is proposed that the plate-shaped member 106 suppresses the telescopic deformation of the metal foil 104.

However, in such EHC100,
In the portion far from the plate member 106, the metal foil 104
However, there is a problem that the telescope-like deformation can not be effectively suppressed. Further, since the ventilation resistance of the plate member 106 is relatively large, there is a problem that the exhaust pressure is increased. Further, the plate-shaped member 106 of the metal foil 104
Since the stagnation is caused by the flow of the exhaust gas in the portion in front of the exhaust gas, there is a problem that the exhaust gas purification rate is lowered in this portion.

The present invention has been made in order to solve the above-mentioned problems of the prior art. Even if the flat plate and the corrugated plate are not joined to each other, problems such as an increase in exhaust pressure and a decrease in exhaust gas purification rate may occur. Metal catalyst that can effectively prevent telescopic deformation of metal foil without inviting
The purpose is to provide (catalytic converter).

[0010]

In order to achieve the above object, a first aspect of the present invention is configured such that a flat metal plate and a corrugated metal plate are spirally wound so as to be alternately laminated. A cylindrical metal foil is a metal catalyst coaxially arranged in a cylindrical member having a substantially cylindrical shape as a carrier for catalyst particles, and is a downstream side of the metal foil when viewed in the flow direction of gas flowing in the cylindrical member. In the above, there is provided a metal catalyst, wherein a lattice-shaped member is arranged in the tubular member so as to maintain a predetermined gap with the metal foil.

According to a second aspect of the invention, in the metal catalyst according to the first aspect, the shaft member is coaxially joined to the center of the metal foil, and the lattice member is joined to the shaft member and the inner peripheral surface of the tubular member. A metal catalyst is provided.

A third aspect of the present invention is the metal catalyst according to the first or second aspect of the present invention, in which the grid-like member radially extends from the center side of the tubular member toward the inner peripheral surface of the tubular member, A metal catalyst comprising a metal wire extending around the axis of a tubular member, wherein the metal wires are formed in a wavy shape.

According to a fourth aspect of the invention, in the metal catalyst according to any one of the first to third aspects, the lattice member is made of a metal material having a coefficient of thermal expansion larger than that of the metal foil. A characteristic metal catalyst is provided.

A fifth invention is a metal catalyst according to the third or fourth invention, wherein the metal catalyst is an energization heat generation type metal catalyst capable of increasing the temperature of the metal foil by energizing the metal foil. While the wire mesh surface is coated with an insulating material, the shaft member is formed of a conductive material, and a metal catalyst is provided which is provided with an energizing means capable of energizing the metal foil through the wire mesh. provide.

A sixth invention is a metal catalyst according to the first or second invention, wherein the metal catalyst is an energization heat generation type metal catalyst capable of increasing the temperature of the metal foil by energizing the metal foil. The metal catalyst is characterized in that the lattice member is formed of an insulating material.

[0016]

EXAMPLES Examples of the present invention will be specifically described below. <First Embodiment> As shown in FIGS. 1 and 2, an energizing heat generating type catalytic converter CS (metal catalyst CS) for purifying exhaust gas of an automobile engine (not shown) has a housing thereof. Is provided with a hollow, substantially cylindrical converter case 1, and an exhaust gas inlet side flange 2 is attached to the upstream end (the left end in FIG. 1) of the converter case 1 and the downstream end (the right end in FIG. 1). Has an exhaust gas outlet side flange 3 attached thereto. Then, the exhaust gas of the engine is introduced into the catalytic converter CS via the inlet side flange 2, and nitrogen oxides, hydrocarbons, etc. in the exhaust gas are purified into harmless substances in the catalytic converter CS, and then the exhaust gas is exhausted. Is downstream via the outlet side flange 3 (silencer side)
It is designed to be discharged to. Converter case 1
Corresponds to the “cylindrical member” described in the claims. In the following, for convenience, the upstream side (left side in FIG. 1) in the exhaust gas flow direction is referred to as “front”, and the downstream side (right side in FIG. 1) is referred to as “rear”.

A metal foil 6 having a substantially cylindrical shaft member 5 attached to the center thereof is disposed in the substantially cylindrical space portion 4 formed in the converter case 1, and the peripheral edge of the metal foil 6 is disposed. The portion is fixed to the inner peripheral surface of the converter case 1 via a substantially cylindrical fixing member 7. Here, the shaft member 5 and the fixing member 7 are made of a conductive material. Since the metal foil 6 is also made of a conductive material as will be described later, the shaft member 5, the metal foil 6 and the fixing member 7 are electrically connected to each other.

The metal foils 6 are made of predetermined metal materials.
(For example, iron-based material) Foil shape (for example, thickness 50μ
The flat plate 8 and the corrugated plate 9 of m) are formed by being spirally wound and fastened so that they are alternately laminated, and have a substantially columnar shape as a whole. Then, on the surface of the metal foil 6, a predetermined noble metal (for example, platinum, rhodium, or palladium) is contained as a main component through a predetermined binder layer (for example, an alumina layer) to reduce nitrogen oxides. It is loaded with catalyst particles capable of or capable of oxidizing hydrocarbons. That is, the metal foil 6 functions as a carrier for the catalyst particles.

Behind the metal foil 6, a flat mesh-like lattice member 11 made of a predetermined material is spread in a direction orthogonal to the axial direction of the converter case 1.
In addition, it is arranged so as to maintain a predetermined gap between the metal foil 6 and the rear end surface. And the grid-shaped member 1
The center of 1 is fixed to the rear end of the shaft member 5, and the peripheral edge is fixed to the inner peripheral surface of the converter case 1.

Each of the lattice members 11 is formed of a predetermined metal material having a coefficient of thermal expansion larger than that of the metal foil 6 (for example, an iron-based material) and is formed into a wavy (curly hair) radial metal wire 12 (plurality of metal wires). ) And the spiral metal wire 13. The radial metal wires 12 are arranged so as to extend radially in the radial direction of the converter case 1 from the converter case axial center side (shaft member side) toward the converter case inner peripheral surface side. On the other hand, the spiral metal wire 13 is arranged so as to extend spirally around the shaft member 5 from the converter case axial center side to reach the converter case inner peripheral surface side.

Here, the radial metal wire 12 and the spiral metal wire 13 are joined at the portions where they intersect with each other, so that the rigidity of the grid-like member 11 is increased and the shape of the grid-like member 11 is prevented from being deformed. The lattice-shaped member 1
In order to increase the degree of freedom of deformation of No. 1, only some intersecting portions may be joined. The surface of the lattice member 11 is coated with an insulating material. Moreover, the fixing portion between the lattice member 11 and the shaft member 5 and the fixing portion between the lattice member 11 and the converter case inner peripheral surface 1 are fixed via an insulating material. Therefore, although the grid-shaped member 11 itself is a conductor formed of a predetermined metal, it is electrically insulated from other members.

By the way, the catalytic converter CS is an electric heating type catalytic converter (EHC), and energizes the metal foil 6 to generate heat when the engine is cold or the catalyst temperature is low after the engine is started. This raises the catalyst temperature and the exhaust gas purification rate in the meantime.

Specifically, the front end portion of the shaft member 5 is the conductor wire 14.
Is connected to a predetermined power supply device (not shown) via the lead wire, and the fixing member 7 is grounded to the vehicle body 16 via the lead wire 15. Here, when a voltage is applied to the shaft member 5 from the power supply device through the lead wire 14, the shaft member 5, the metal foil 6, and the fixing member 7 are electrically connected to each other, as described above. An electric current will flow through it. Here, since the metal foil 6 is formed of a thin plate-shaped or foil-shaped material, its electric resistance is much higher than that of the shaft member 5 or the fixed member 7. Therefore, heat is generated only in the metal foil 6 due to such energization, the temperature of the metal foil 6 rises, and the exhaust gas purification rate of the catalytic converter CS is increased. As described above, since the grid-shaped member 11 is electrically insulated from other members, even if the metal foil 6 and the grid-shaped member 11 are in contact with each other, an electrical short circuit (short circuit) occurs in the metal foil. Of course, does not occur.

In such a catalytic converter CS, since the grid-like member 11 is provided slightly behind the metal foil 5, the metal foil 5 has a converter case due to acceleration / deceleration of the automobile, vibration of the converter case 1 or thermal stress. Even when a force is applied in the axial direction, rearward displacement or displacement of each part of the metal foil 5 is blocked, and the telescopic deformation of the metal foil 5 does not occur. A similar grid-like member may be provided on the front side of the metal foil 6.

Since the radial metal wire 12 and the spiral metal wire 13 constituting the grid-shaped member 11 are thin, the grid-shaped member 11 does not substantially cause ventilation resistance and the exhaust pressure of the engine does not rise. Further, since the stagnation part of the exhaust gas does not occur on the upstream side of the lattice member 11, the exhaust gas purification rate is enhanced. Since a slight gap is provided between the rear end portion of the metal foil 6 and the lattice member 11,
The lattice member 11 does not block the holes of the metal foil 6.

Further, in general, the metal foil 6 undergoes a relatively large thermal deformation due to a temperature change thereof, and particularly a large thermal deformation occurs in the circumferential direction. Therefore, the thermal deformation causes the lattice member 11 to rotate in the circumferential direction. A strong radial force will be applied. However, the grid member 1
1 is composed of a radial metal wire 12 and a spiral metal wire 13 that is easily deformable in the circumferential direction and the radial direction, and uses a wavy metal wire that is easily deformable. Since it is also formed of a material having a large coefficient of thermal expansion, even if the metal foil 6 is thermally deformed, damage such as cracks does not occur in the lattice member 11.

In the first embodiment, the grid member 11 is made of metal and electrically insulated from other members, but the grid member 11 may be made of an insulating material. In addition, in the first embodiment, the catalytic converter CS is an energization heat generation type.
Although it is described as (EHC), it is not necessary to electrically insulate the grid-like member 11 from other members unless the catalytic converter is of the energization and heat generation type.

<Second Embodiment> The second embodiment will be described below with reference to FIGS. 3 and 4. The basic structure of the second embodiment is the first embodiment shown in FIGS. In order to avoid duplication of explanation, common members are given the same numbers as in the first embodiment and their explanations are omitted. Only the points different from the first embodiment will be explained below. .

As shown in FIGS. 3 and 4, the energization heat generation type catalytic converter CS '(metal catalyst C according to the second embodiment is used.
In S '), the fixing member 7'is formed of an insulating material.
Then, the electrode portion 21 is electrically connected to the peripheral portion of the metal foil 6, and the electrode portion 21 is electrically connected to a power supply device (not shown) via a lead wire 22. Further, an insulating material is not interposed between the grid-shaped member 11, the shaft member 5, and the fixed portion, so that the shaft member 5 and the grid-shaped member 11 are electrically connected. The peripheral edge of the lattice member 11 is grounded to the vehicle body 24 via the conductor 23.

Therefore, in the catalytic converter CS ', when a voltage is applied from the power supply device to the electrode portion 21 when the engine is cold, a current flows in the order of the electrode portion 21, the metal foil 6, the shaft member 5, the grid-like member 11 and the conducting wire. 23 to the vehicle body 24, and the metal foil 6 generates heat to raise the catalyst temperature and raise the exhaust gas purification rate, as in the case of the first embodiment.

According to the second embodiment, since no special electric system for connecting the shaft member 5 to the power supply device or the vehicle body as in the case of the first embodiment is required, the power supply means to the catalytic converter CS 'is provided. Is simplified. In addition, other actions
The effect is similar to that of the first embodiment.

[0032]

According to the first aspect of the invention, since the lattice-like member is provided on the downstream side of the metal foil when viewed in the gas flow direction, acceleration and deceleration are applied to the tubular member and vibration is caused in the tubular member. Alternatively, even if a thermal stress is applied and an axial force is applied to the metal foil, the grid member prevents the metal foil from being displaced or displaced in the axial direction, and the telescopic deformation of the metal foil does not occur. Further, since the gap is provided between the metal foil and the lattice member, the lattice member does not block the holes of the metal foil, and the performance of the metal catalyst as a catalyst (for example, in the case of an exhaust gas purification catalyst, Exhaust gas purification rate) is increased. Moreover, since the lattice member has a small ventilation resistance, the exhaust pressure is prevented from increasing when the metal catalyst is used for purifying engine exhaust gas. Furthermore, since gas stagnation does not occur upstream of the lattice-like member, the performance of the metal catalyst as a catalyst is further enhanced.

According to the second invention, basically, the same operation and effect as those of the first invention can be obtained. Further, since the shaft member is coaxially joined to the central portion of the metal foil and the lattice member is joined to the shaft member and the inner peripheral surface of the tubular member, the supporting rigidity of the metal foil and the lattice member is enhanced. .

According to the third invention, basically, the same operation and effect as those of the first or second invention can be obtained. Furthermore, the grid-shaped members are each formed in a wavy shape, and a metal wire extending radially from the center side of the tubular member toward the inner peripheral surface of the tubular member,
Since the wire mesh is composed of a metal wire that extends around the axis of the tubular member, the degree of freedom of deformation increases, and even if a strong force is applied to the grid member due to thermal deformation of the metal foil, No damage such as cracks. In addition, since the ventilation resistance of the wire mesh is very small, when the metal catalyst is used for purifying engine exhaust gas, the exhaust pressure is effectively prevented from increasing.

According to the fourth invention, basically, the same action and effect as any one of the first to third inventions can be obtained. Further, since the lattice-shaped member is formed of a metal material having a coefficient of thermal expansion larger than that of the metal foil, the degree of freedom of deformation of the lattice-shaped member is increased, and a strong force is applied to the lattice-shaped member due to the thermal deformation of the metal foil. Even in the case of being damaged, the lattice member is not damaged.

According to the fifth invention, basically, the same action and effect as those of the third or fourth invention can be obtained. Furthermore, since the metal catalyst is of the electric heating type and the wire mesh surface is coated with an insulating material, no electrical short circuit occurs in the metal foil even when the metal foil and the wire mesh contact each other. Further, since the shaft member or the metal foil can be energized via the wire mesh, the energization system to the metal foil is simplified.

According to the sixth invention, basically, the same operation and effect as those of the first or second invention can be obtained. Furthermore, since the metal catalyst is of the electric heating type and the grid member is made of an insulating material, no electrical short circuit occurs in the metal foil even when the metal foil and the grid member come into contact with each other.

[Brief description of drawings]

FIG. 1 is a partial sectional side view of a catalytic converter showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA of the catalytic converter shown in FIG.

FIG. 3 is a partial sectional side view of a catalytic converter showing a second embodiment of the present invention.

FIG. 4 is a cross-sectional view taken along line BB of the catalytic converter shown in FIG.

FIG. 5 is a partial sectional side view of a conventional catalytic converter.

FIG. 6 is a cross-sectional explanatory view taken along the line CC of the conventional catalytic converter shown in FIG.

[Explanation of symbols]

 CS, CS '... Catalytic converter (metal catalyst) 1 ... Converter case 4 ... Space part 5 ... Shaft member 6 ... Metal foil 7,7' ... Fixing member 8 ... Flat plate 9 ... Corrugated plate 11 ... Lattice member 12 ... Radial metal Wire 13 ... Spiral metal wire 14, 15, 22, 23 ... Conductive wire 16, 24 ... Car body (earth) 21 ... Electrode part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01J 35/02 ZAB G 8017-4G 35/04 ZAB 8017-4G 321 A 8017-4G F01N 3/20 ZAB K

Claims (6)

[Claims] 1. A substantially cylindrical metal foil formed by spirally winding a metal flat plate and a metal corrugated plate so as to be alternately laminated, and a substantially cylindrical cylinder as a carrier for catalyst particles. A metal catalyst arranged coaxially in the tubular member, wherein a grid-like member is provided between the metal foil and the tubular member on the downstream side of the metal foil when viewed in the flow direction of the gas flowing in the tubular member. A metal catalyst, characterized in that the metal catalyst is arranged so as to maintain a predetermined gap. 2. The metal catalyst according to claim 1, wherein the shaft member is coaxially joined to the central portion of the metal foil, and the lattice member is joined to the shaft member and the inner peripheral surface of the tubular member. A metal catalyst characterized by that. 3. The metal catalyst according to claim 1 or 2, wherein the lattice member is a metal wire extending radially from the center side of the tubular member toward the inner peripheral surface of the tubular member, and the tubular member. 1. A metal catalyst comprising a metal wire extending around the axis of a member, wherein each metal wire is formed in a wavy shape. 4. The metal catalyst according to claim 1, wherein the lattice member is made of a metal material having a thermal expansion coefficient larger than that of the metal foil. Metal catalyst to do. 5. The metal catalyst according to claim 3 or 4, wherein the metal catalyst is an energization heat generation type metal catalyst capable of increasing the temperature of the metal foil by energizing the metal foil. A metal catalyst having a surface coated with an insulating material, a shaft member formed of a conductive material, and provided with an energizing means capable of energizing a metal foil through a wire mesh. 6. The metal catalyst according to claim 1 or 2, wherein the metal catalyst is an energization heat generation type metal catalyst capable of increasing the temperature of the metal foil by energizing the metal foil. A metal catalyst, wherein the plate-shaped member is formed of an insulating material.