JPH0610653A - Exhaust emission control system - Google Patents

Abstract

PURPOSE:To improve the purifying effect of the exhaust gas by consisting a rod-shaped electrode of a cylindrical body where an opening is formed at its upstream end part and its downstream end part is closed, and forming a plurality of communicating holes in the circumferential wall of the cylindrical body and a plurality of holes in a catalyst body. CONSTITUTION:An exhaust emission control system 1 is provided with an outer cylinder 4 composed of a conductive material and a conductive monolithic catalyst 5 stored therein. A rod-shaped electrode 6 consists of a cylindrical body where an opening 8 is formed at its upstream end part, and the downstream end part is closed. A lot of communicating holes 10 are formed in a circumferential wall 9 of the cylindrical body. A lot of communicating holes are formed in the foil-shaped metal consisting of the conductive monolithic catalyst 5. The exhaust gas flowing into the cylindrical body flows through a lot of communicating holes 10 to the conductive monolithic catalyst 5, and through the communicating holes in the foil-shaped metal, and is diffused into the conductive monolithic catalyst 5. Thus, the purifying effect of the exhaust gas can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying device, and more particularly, to an engine starting time,
The present invention relates to an exhaust gas purifying device that can quickly raise the catalyst temperature to an activation temperature by energizing a conductive monolith catalyst having conductivity.

[0002]

2. Description of the Related Art In an exhaust gas purifying device provided in an exhaust pipe, a conductive rod-shaped electrode or a conductive monolith catalyst formed by winding a foil material carrying a catalyst around a solid electrode is connected to the other electrode. It is housed in a tubular member that has a low exhaust gas temperature, and when the engine temperature is low, the conductive monolith catalyst is energized to quickly raise the catalyst temperature to the activation temperature, and the exhaust gas is always desired. An exhaust gas purifying device capable of purifying as described above is known (for example, Japanese Utility Model Laid-Open No. 63-67609).

[0003]

However, in such an exhaust gas purifying apparatus, since the solid rod-shaped electrode is arranged substantially at the center in the radial direction of the exhaust pipe, the flow velocity of the exhaust gas is reduced. The largest part of the space cannot be used for purification of exhaust gas, and as a result, it becomes difficult to sufficiently improve the purification performance of exhaust gas, and the pressure of exhaust gas increases to increase engine output. There is a problem in that the weight of the exhaust gas purifying device cannot be reduced.

[0004]

It is an object of the present invention to provide a conductive monolithic catalyst which is formed by arranging a catalyst carrier carrying a catalyst around a rod-shaped electrode and through which exhaust gas can pass, and the conductive monolithic catalyst. In an exhaust gas purifying apparatus that houses a monolith catalyst and has a tubular member connected to an electrode, while improving the exhaust gas purifying action of the conductive monolith catalyst,
An object of the present invention is to provide an exhaust gas purifying apparatus which can prevent an increase in exhaust gas pressure and prevent a decrease in engine output, and which can be reduced in weight.

[0005]

According to the first aspect of the present invention, the object of the present invention is to construct the rod-shaped electrode from a cylindrical body having an opening formed at the upstream end and a closed downstream end. Then
While forming a plurality of communication holes on the peripheral wall of the tubular body,
This is achieved by forming a plurality of holes in the catalyst carrier so that the exhaust gas can diffuse outward.

According to the second aspect of the present invention, the object of the present invention is to form the rod-shaped electrode by a tubular body having openings at both ends, and to fill the tubular body with a conductive monolith catalyst. It is achieved by In a preferred embodiment of the present invention, the rod-shaped electrode is provided with an opening at an upstream end thereof and is formed by a tubular body having a closed downstream end, and a plurality of electrodes are provided on a peripheral wall of the tubular body. A plurality of communication holes are formed in the foil-shaped substance together with the communication holes, and a catalyst is carried in the tubular body, and a foil-shaped substance having a plurality of holes is wound to form the communication hole. It is filled with a conductive monolith catalyst.

[0007]

According to the first aspect of the present invention, the rod-shaped electrode is
Since the upstream end has an opening and the downstream end is formed by a closed cylindrical body, the exhaust gas flowing in the substantially central portion of the exhaust pipe flows into the cylindrical body through the opening. However, since the downstream end of the tubular body is closed and a plurality of communication holes are formed in the peripheral wall of the tubular body, the exhaust gas once flowing into the tubular body is discharged from the plurality of communication holes. Since a plurality of holes are formed in the catalyst carrier supporting the catalyst so that the exhaust gas can diffuse to the outside while flowing toward the conductive monolith catalyst, the conductive monolith catalyst passes through these holes. Spread inside. Therefore, it is possible to significantly increase the number of times the exhaust gas flowing in the substantially central portion of the exhaust pipe contacts the catalyst, improve the exhaust gas purification function, and increase the pressure of the exhaust gas. Since it is possible to prevent it, it is possible to prevent the output reduction of the engine, and further, since the rod-shaped electrode is hollow,
It is possible to reduce the weight of the exhaust gas purification device.

According to the second aspect of the present invention, since the rod-shaped electrode is formed by the tubular body having the openings at both ends, the exhaust gas flowing through the substantially central portion of the exhaust pipe is opened at the upstream end. From the part, flowing into the tubular body, since the conductive monolith catalyst is filled in the tubular body, the exhaust gas flowing into the tubular body is due to the conductive monolith catalyst filled in the tubular body, It is purified and flows out from the downstream end of the tubular body to the downstream side of the exhaust pipe. Therefore, the space in the center of the exhaust pipe where the flow velocity of the exhaust gas is highest can be effectively utilized for purifying the exhaust gas, so that the exhaust gas purification function can be improved and the exhaust gas can be improved. Since the cross-sectional area of the exhaust pipe through which the gas flows increases, it becomes possible to prevent the pressure of the exhaust gas from increasing and to prevent the output of the engine from decreasing. Furthermore, since the rod-shaped electrode is hollow, the exhaust gas It is possible to reduce the weight of the purification device.

According to a preferred embodiment of the present invention, the rod-shaped electrode is formed by a tubular body having an opening at its upstream end and a closed downstream end. The exhaust gas flowing through the central portion flows into the tubular body through the opening and is subjected to the purifying action by the conductive monolith catalyst filled in the tubular body, and further, the downstream end portion of the tubular body is closed and the tubular body is closed. A plurality of communication holes are formed on the peripheral wall of the cylindrical body, and a plurality of holes are formed in the foil-like substance that constitutes the conductive monolith catalyst filled in the cylindrical body. The inflowing exhaust gas flows from the plurality of holes formed in the foil-shaped substance and the plurality of communication holes formed in the peripheral wall of the tubular body toward the conductive monolith catalyst provided outside the tubular body, and further, A catalyst for supporting a conductive monolith catalyst provided outside the tubular body. A carrier, a plurality of holes are formed, through these holes, to diffuse the conductive monolith catalyst. Therefore, the exhaust gas flowing through the substantially central portion of the exhaust pipe first comes into contact with the conductive monolith catalyst filled in the tubular body, and further comes into contact with the conductive monolith catalyst provided outside the tubular body. The number of contacts with the exhaust gas is significantly increased, the exhaust gas purification function can be improved, and the exhaust gas pressure can be prevented from increasing, so that the engine output can be prevented from decreasing.
Furthermore, since the rod-shaped electrode is hollow, it is possible to reduce the weight of the exhaust gas purification device.

[0010]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a schematic vertical sectional view of an exhaust gas purifying apparatus according to an embodiment of the present invention. In FIG. 1, the exhaust gas purification device 1 is provided in the large diameter portion of the exhaust pipe 2, and the large diameter portion of the exhaust pipe 2 forms a casing 3 of the exhaust gas purification device 1.

The exhaust gas purifying apparatus 1 is provided with, in a casing 3, an outer cylinder 4 made of a conductor, and a conductive monolith catalyst 5 accommodated therein. As shown in FIG. 2, the conductive monolith catalyst 5 has a foil-shaped or thin-plate-shaped metal (hereinafter, generally referred to as a foil) on which the catalyst is carried, and the distance between the foil surfaces facing each other becomes random. As described above, it is formed by winding around the rod-shaped electrode 6, and the electrode 7 is connected to the outer cylinder 4. The conductive monolith catalyst 5 is formed in such a shape in order to increase the surface area and increase the chances of contact between the exhaust gas and the catalyst.

As shown in FIG. 3, the rod-shaped electrode 6 is
It is formed by a hollow cylinder having an opening 8 at its upstream end and a closed downstream end, and a large number of communication holes 10 are formed in its peripheral wall 9. Further, although not shown, a large number of communicating holes are also formed in the foil-shaped metal forming the conductive monolith catalyst 5. Further, between the outer cylinder 4 and the casing 3, a support member 11 made of a hollow cylindrical ceramic that supports the outer cylinder 4 with the casing 3 is arranged.

Further, the outer cylinder 4 is controlled by the pressure of the exhaust gas,
To prevent being pushed to the downstream side, the casing 3
An annular holding member 12 attached to the inner wall surface of the outer cylinder 4 is arranged so as to contact the downstream end of the outer cylinder 4. The abutting portion of the holding member 12 with the outer cylinder 4 is coated with an insulating material in order to prevent the outer cylinder 4 and the exhaust pipe 2 from being short-circuited.

In the exhaust gas purifying apparatus according to this embodiment having the above-mentioned structure, the exhaust gas flowing through the substantially central portion of the exhaust pipe 2 flows from the opening 8 into the hollow cylinder forming the electrode 6. Furthermore, since the downstream end of the hollow cylinder is closed and a large number of communication holes 10 are formed in the peripheral wall 9 of the hollow cylinder, the exhaust gas flowing into the hollow cylinder is A large number of communication holes are formed in the foil-shaped metal that carries the catalyst that constitutes the conductive monolith catalyst 5 and flows toward the conductive monolith catalyst 5. Therefore, through these communication holes, It diffuses inside the conductive monolith catalyst 5. Therefore, the number of times the exhaust gas flowing in the substantially central portion of the exhaust pipe 2 comes into contact with the catalyst can be significantly increased, the exhaust gas purification function can be improved, and the exhaust gas pressure can be increased. Since it is possible to prevent the engine output from decreasing, and further, since the rod-shaped electrode 6 is hollow,
It is possible to reduce the weight of the exhaust gas purification device 1.

FIG. 4 is a schematic vertical sectional view of an exhaust gas purifying apparatus according to another embodiment of the present invention. In the embodiment shown in FIG. 4, a catalyst is supported in a hollow cylinder forming the electrode 6, and a foil-shaped metal having a large number of communication holes is used, and the distance between the foil surfaces facing each other is small. The embodiment is different from the embodiment shown in FIGS. 1 to 3 only in that the conductive monolith catalyst 5 formed by winding in a random manner is filled.

Therefore, according to this embodiment, the exhaust pipe 2
Of the exhaust gas flowing in the substantially central portion of the hollow cylinder that flows into the hollow cylinder forming the electrode 6 from the opening 8 and undergoes the purifying action of the conductive monolith catalyst 5 filled in the hollow cylinder. The peripheral end 9 of the hollow cylinder is closed at the downstream end.
In addition, a large number of communication holes 10 are formed in the hollow cylinder, and a large number of communication holes are formed in the foil-shaped metal forming the conductive monolith catalyst 5 filled in the hollow cylinder. The inflowing exhaust gas is directed from the multiple communication holes formed in the foil-shaped metal and the multiple communication holes 10 formed in the peripheral wall 9 of the hollow cylinder toward the conductive monolith catalyst 5 provided outside the hollow cylinder. A large number of communication holes are formed in the foil-shaped metal that carries the catalyst that constitutes the conductive monolith catalyst 5 provided outside the hollow cylinder. The monolithic catalyst 5 diffuses inside. As a result, the exhaust gas flowing through the substantially central portion of the exhaust pipe 2 first comes into contact with the conductive monolith catalyst 5 filled in the hollow cylinder, and further comes into contact with the conductive monolith catalyst 5 provided outside the hollow cylinder. Therefore, the number of times of contact with the catalyst is significantly increased, the exhaust gas purification function can be improved, and the increase in the exhaust gas pressure can be prevented, so that the engine output can be prevented from lowering. Furthermore, since the rod-shaped electrode 6 is hollow,
It is possible to reduce the weight of the exhaust gas purification device.

FIG. 5 is a schematic vertical sectional view of an exhaust gas purifying apparatus according to still another embodiment of the present invention. The embodiment shown in FIG. 5 is shown in FIG. 4 only in that the rod-shaped electrode 6 is formed by a hollow cylinder having openings formed at both ends and no communication hole is formed in its peripheral wall. Different from the embodiment.

Therefore, according to this embodiment, the exhaust pipe 2
The exhaust gas flowing through the substantially central portion of the above flows into the hollow cylinder that constitutes the electrode 6 from the opening at the upstream end, and in the hollow cylinder, the catalyst is supported and a large number of communication holes are formed. Since the conductive monolith catalyst 5 formed by winding a foil-shaped metal is filled, the exhaust gas flowing into the hollow cylinder is a foil-shaped metal of the conductive monolith catalyst 5 filled in the hollow cylinder. While being diffused in the conductive monolith catalyst 5 through a large number of communication holes formed in the hollow cylinder, it is purified by the conductive monolith catalyst 5 filled in the hollow cylinder and exhausted from the downstream end of the hollow cylinder. 2 flows out to the downstream side. Therefore, the space in the central portion of the exhaust pipe 2 where the flow velocity of the exhaust gas is highest can be effectively utilized for purifying the exhaust gas, so that the exhaust gas purifying function can be improved and Since the cross-sectional area of the exhaust pipe 2 through which the exhaust gas flows increases, it becomes possible to prevent the pressure of the exhaust gas from increasing and prevent the output of the engine from decreasing. Furthermore, the rod-shaped electrode 6 is hollow. Therefore, the weight of the exhaust gas purification device 1 can be reduced.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say. For example, in the above-mentioned embodiment, the conductive monolith catalyst 5 is formed in a cylindrical shape, but it is not limited to a cylindrical shape as long as it has a cylindrical shape, and similarly, the outer cylinder 4 is also formed. However, the shape is not limited to the shape of the above embodiment as long as the shape can accommodate the conductive monolith catalyst 5.

In the above embodiment, the supporting member 6 made of ceramic is used to support the conductive monolith catalyst 5 and the outer cylinder 4, but the supporting member 6 is made of an insulating material other than ceramic. May be. Furthermore, FIG.
In the embodiment shown in FIG. 2, a large number of communication holes are formed in the foil-shaped metal of the conductive monolith catalyst 5 filled in the hollow cylinder forming the electrode 6, so that the exhaust gas is discharged into the conductive monolith catalyst 5 However, the exhaust gas passes through the conductive monolith catalyst 5 filled in the hollow cylinder and flows out to the downstream side of the exhaust pipe 2 without providing a communication hole. Good.

Further, in the above-mentioned embodiment, the catalyst is supported on the foil-shaped metal, but the material may not be the metal as long as it has conductivity, and further the honeycomb-shaped catalyst carrier is used. It is also possible to use a catalyst carrier through which exhaust gas can pass.

[0022]

According to the present invention, there is provided a conductive monolith catalyst which is formed by arranging a catalyst carrier carrying a catalyst around a rod-shaped electrode and which has conductivity and through which exhaust gas can pass. In an exhaust gas purifying apparatus that contains a conductive monolith catalyst and has a tubular member connected to the other electrode,
It is possible to provide an exhaust gas purifying apparatus that can improve the exhaust gas purifying action of a conductive monolith catalyst, prevent an increase in exhaust gas pressure, and prevent a decrease in engine output, which enables weight reduction. become.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of an exhaust gas purifying apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a conductive monolith catalyst and an outer cylinder.

FIG. 3 is a schematic perspective view of a rod-shaped electrode.

FIG. 4 is a schematic vertical sectional view of an exhaust gas purifying apparatus according to another embodiment of the present invention.

FIG. 5 is a schematic vertical sectional view of an exhaust gas purifying apparatus according to still another embodiment of the present invention.

[Explanation of symbols]

 1 Exhaust Gas Purification Device 2 Exhaust Pipe 3 Casing 4 Outer Cylinder 5 Conductive Monolith Catalyst 6 Rod-shaped Electrode 7 Electrode 8 Opening 9 Circumferential Wall 10 Communication Hole 11 Supporting Member 12 Holding Member

Claims (3)

[Claims] 1. A conductive monolith catalyst having conductivity, which is formed by arranging a catalyst carrier carrying a catalyst around a rod-shaped electrode, and contains the conductive monolith catalyst. In the exhaust gas purifying apparatus including a tubular member connected to the other electrode, the rod-shaped electrode has a tubular body in which an opening is formed at an upstream end thereof and a downstream end thereof is closed. And a plurality of communication holes are formed on the peripheral wall of the tubular body, and a plurality of holes are formed in the catalyst carrier so that the exhaust gas can diffuse outward. Purification device. 2. A conductive monolith catalyst which has conductivity and is formed by arranging a catalyst carrier carrying a catalyst around a rod-shaped electrode, and which contains the conductive monolith catalyst. In the exhaust gas purification device including a tubular member connected to the electrode, the rod-shaped electrode is formed by a tubular body having openings at both ends, and the conductive monolith catalyst is provided in the tubular body. The exhaust gas purifying apparatus according to claim 1, wherein the exhaust gas purifying apparatus is filled. 3. The conductive monolith catalyst formed by winding a foil-shaped material having a plurality of holes formed therein, and carrying the catalyst in the cylindrical body, according to claim 1. Exhaust gas purification device.