JPH05269387A - Exhaust gas purifying catalystic converter - Google Patents

Abstract

PURPOSE:To improve the fail-safe function by allowing the positive and negative electrode members connected to each metallic catalyst carrier provided in a shell to pierce the insulated metallic shell wall and electrically connecting the positive electrode members and the negative electrode members through a conductive radiating plate in parallel. CONSTITUTION:Metallic catalyst carriers 3, 4 and 5 are arranged, heated and allowed to act as a heater in an exhaust gas purifying catalytic converter, and the converter is placed in the exhaust passage of an internal combustion engine. The plural catalyst carriers 3, 4 and 5 are provided in a shell 2. The positive and negative electrode members 6,...11 connecting the carriers 3, 4 and 5 are allowed to pierce the insulated metallic shell wall, and the positive electrode members 6, 7 and 8 and the negative electrode members 9, 10 and 11 are electrically connected in parallel through radiating plates 21 and 22. Consequently, even when any carrier is not energized, the other carriers are energized, and the fail-safe function is 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 purification catalytic converter device provided in an exhaust passage of an internal combustion engine.

[0002]

BACKGROUND ART CO in the exhaust is interposed in an exhaust passage of an internal combustion engine, HC, the exhaust purifying catalyst converter device for purifying pollutants such as NO _X was heated to be a predetermined activation temperature If it is not in a state, a sufficient catalytic action cannot be exhibited, and for example, immediately after a cold start of the engine, it takes some time for the exhaust gas purification performance to reach a sufficient level.

Therefore, it has been conventionally considered that the catalyst carrier carrying the catalyst has an electric heater structure. By the way, in recent years, a catalyst carrier to which a metal catalyst carrier is applied, which is advantageous in terms of heat capacity and pressure loss, has been considered. Since this metal catalyst carrier is composed of a metal plate, an exhaust gas purification catalytic converter device has been proposed in which the metal plate itself is used as a heating resistor, that is, an electric heater.

In such a catalytic converter device, an electrode mounting structure for energizing the metal catalyst carrier is required.
A conventional electrode mounting structure is disclosed in Japanese Patent Application Laid-Open No. 48-54321.
There is one as shown in Japanese Patent Publication. In this structure, a plurality of metal plates are spirally fixed around a conductive bar material, a + side electrode member is attached to the outside thereof, and the central bar material serves as a negative electrode.

[0005]

However, in such a conventional electrode mounting structure for a catalytic converter device,
The electrode member and each metal plate have a structure that tends to cause poor contact due to distortion, etc. Also, heat is transferred from the high temperature metal shell to the electrode, and the harness connected to the electrode is thermally severely oxidatively corroded. It becomes an easy situation.

Further, since only one metal catalyst carrier is energized through a pair of positive and negative electrode members, if an abnormality occurs such that the energization is cut off, heating is not performed at all and the catalyst Since it is not activated, there is a problem in reliability in this respect as well. The present invention has been made in view of such conventional problems, and can reliably electrically connect the electrode and the metal catalyst carrier, the heat dissipation of the electrode portion is also satisfied, and the carrier is pluralized. By reducing the heat capacity of each carrier and reducing the current flowing through each carrier, even if there is a locally large resistance, the heat generation distribution can be made uniform and local heat generation can be suppressed to improve durability. It is an object of the present invention to provide an exhaust gas purification catalytic converter device having a structure that can be formed.

[0007]

For this reason, the catalytic converter device for exhaust gas purification according to the present invention is provided with a plurality of metallic catalyst carriers having a heater function in a metallic shell and is connected to each metallic catalyst carrier with a positive or negative sign. The electrode member of the above is projected through the metal shell wall in an insulated state, and the positive electrode members and the negative electrode members are electrically connected to each other through the heat radiating plate made of a conductive material. The structure is such that they are connected in parallel.

[0008]

In this structure, when a voltage is applied between any one pair of positive and negative electrode members, all metal catalyst carriers are energized via the heat radiating plate to generate heat. Further, heat is transferred from the metal shell wall, which is heated to a high temperature by receiving exhaust heat, to the electrode member, but good heat dissipation is performed via the heat dissipation plate, so that the temperature rise of the electrode member is suppressed.

Since the metal catalyst carriers are connected in parallel via the respective electrode members, even if an abnormality occurs in the current-carrying system to one of the metal catalyst carriers, the other metal catalyst carrier is connected to the other metal catalyst carriers. Energization is secured.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the embodiments shown in the drawings. In FIG. 1 showing an embodiment, a catalytic converter device 1 according to the present invention is installed in an exhaust passage of an internal combustion engine (not shown). In the catalytic converter device 1, a plurality of metallic catalyst carriers 3, 4, 5 are arranged at intervals in the exhaust flow direction in a metallic shell 2 formed by fastening two divided members. The metal catalyst carriers 3, 4, 5 are formed by alternately laminating corrugated metal plates carrying a catalyst and flat plates and winding them in an elliptical shape by brazing both ends. The catalyst may be supported after winding.

Flange portions are brought into contact with the outer surfaces of the metal catalyst carriers 3, 4, 5 on both sides in the minor axis direction of the elliptical cross section, and the other end portions are penetrated through the wall of the metal shell 2 to form positive electrode members, respectively. 6, 7, 8 and-side electrode members 9, 10, 11 are mounted. Of these, the + side electrode member 7 and the − side electrode member 10 mounted on the metal catalyst carrier 4 in the middle have a larger amount of protrusion from the metal shell 2 than the other electrode members, and are connected to the harness to directly apply a voltage. It is a terminal to be applied. A male screw is formed on the protruding end of each electrode member 6-11.

Between the outer peripheral surface of each metal catalyst carrier 3, 4, 5 and the inner peripheral surface of the metal shell 2, there are provided annular mat members 12, 13, which are electrically insulating materials and have a buffer property. 1
4 is installed. The mat member is formed of, for example, a mixture of ceramic fibers, a heat expansion material, an organic binder, and the like. In addition, the hole which penetrates each said electrode member 6-11 of the metal shell 2 has an outer diameter larger than the diameter of the electrode member 6-11, and the mat member 12, 13 and 14 are interposed, and the electrical insulation between the electrode members 6 to 11 and the metal shell 2 is maintained.

Then, the annular electrical insulating members 15 to 20 are fitted and inserted into the portions of the electrode members 6 to 11 projecting from the outer surface of the metal shell 2, and from there, the + side electrode members 6 and 6 are inserted.
7, 8 and negative electrode members 9, 10 and 11 are fitted and fitted with long plate-shaped conductive heat dissipation plates 21 and 22, respectively, and screws of the electrode members 6 to 11 are further mounted thereon. The nuts 23 to 28 are screwed into the cut portions so that the heat radiating plates 21 and 22 are connected to the positive side electrode members 6, 7, 8 and the negative side electrode members 9, 1 respectively.
It is fastened to 0 and 11. As a result, the metal catalyst carriers 3 to 5 are connected to the electrode members 6 to 11 and the heat dissipation plates 21 and 22.
Are electrically connected in parallel via.

Although the heat sink and the metal shell 2 are electrically connected to each other through the electric insulating members 15 to 20 in such a structure, the heat sink 2 is made to ensure more reliable insulation.
A structure in which an electric insulating material is applied in layers on the surface of the metal shell around the portions facing the Nos. 1 and 22 and the outer periphery thereof, or the electric insulating members are connected to each other to form a plate larger than the heat radiating plate. Good.

Next, the operation of the catalytic converter device according to the present invention having such a structure will be described. + Side electrode member 7
When a predetermined voltage is applied between the negative electrode member 10 and the negative electrode member 10, the metal catalyst carrier 4 interposed between the electrode members 7 and 10 and the electrode members 6 and 9 and the heat sinks 21 and 22 are used. The metallic catalyst carriers 3, 5 between the electrode members 8, 11 are also energized to generate heat. As is well known, the amount of heat generation is determined by the amount of electricity supplied and the resistance value of each metal catalyst carrier.

Further, the catalyst carrier is composed of a plurality of catalysts, the heat capacity of each carrier is reduced, and the current flowing through each carrier is reduced. It is possible to suppress heat generation and improve the durability of the carrier. Specifically, FIG. 2 (A)
As described above, the heat generation amount W ₀ when the voltage V ₀ is applied to the single catalyst carrier 41 having the resistance value R is expressed by the following equation, where I ₀ is the current flowing through the carrier 41.

W ₀ = V ₀ I ₀ = I ₀ ² R = V ₀ ² / R ... Next, as shown in FIG. 2B, each resistance value is r 3.
Electrodes of the catalyst carriers 42, 43 and 44 (the total catalyst capacity of the three carriers is the same as the catalyst capacity of the carrier 41) are connected to each other with the same polarity, and a voltage V ₀ is applied between the two connection parts. heating value W ₁ in the case of the current flowing between connection portions I ₁
Then, it is expressed by the following equation.

W ₁ = V ₀ I ₁ = V ₀ ² / r ... If the carrier 41 and the carriers 42, 43, 44 are heated to the same temperature, FIG. 2 (B) The type has a heat capacity of 1
In order to decrease to / 3, 1 / 3W ₀ = W ₁ , and by substituting the formula into this, (1/3) × V ₀ ² / R = V ₀ / r ∴r = 3R ∴I ₀ = V ₀ / R I ₁ = V ₀ / r = (1/3) × V ₀ / R = (1/3) ×
I ₀ , and the current I ₁ flowing through each of the carriers 42, 43, 44 is 1/3 of the current I ₀ flowing through the carrier 41.

As a result, the catalysts supported on the metallic catalyst carriers 3 to 5 are heated and activated immediately after the internal combustion engine is started, and the pollutants (CO, HC, NOx, etc.) in the exhaust gas are oxidized and reduced. Can be satisfactorily purified by promoting. And
As an operation of the configuration according to the present invention, the electrical connection between each electrode member 6 to 11 and the metal catalyst carrier 3 to 5 has a wide contact surface on the outer surface of the metal catalyst carrier 3 to 5. Therefore, the contact failure can be favorably suppressed.

Further, since the electrode members 6 to 8 and 9 to 11 are connected via the heat radiating plates 21 and 22 arranged outside the metal shell 2, the metal shell 2 to the electrode members 6 are connected. Exhaust heat transmitted to the heat sinks 11 to 11
It is possible to radiate heat into the outside air through 2 well, and
The temperature rise of the electrode members 7 and 9 to which a harness (not shown) is connected is suppressed, and thermal deterioration such as oxidation and corrosion of the harness can be effectively prevented.

Further, since a plurality of metal catalyst carriers 3 to 5 are provided and electrically connected in parallel, even if an abnormality occurs such that the current to any of the metal catalyst carriers is cut off, the other metal catalyst carriers 3-5 are electrically connected in parallel. Electricity is supplied to the catalyst carrier to ensure minimum activation of the catalyst, which is also advantageous in terms of fail-safe. Since the harness is connected to the central electrode member in this embodiment, the heat generation distribution can be equalized as compared with the structure in which the harness is connected to the end electrode member, so that heat generation is locally suppressed and durability is improved. It is possible to improve the purification performance.

[0022]

As described above, according to the present invention, since the electrode member is formed to have a wide contact surface on the outer surface of the metal catalyst carrier, contact failure can be favorably suppressed, and the metal shell By radiating the exhaust heat transmitted from each electrode member through the heat radiating plate, it is possible to effectively prevent thermal deterioration such as oxidation and corrosion of the harness connected to the electrode member, and it is possible to electrically connect a plurality of metal catalyst carriers to each other. Since they are connected in parallel with each other, even if an abnormality occurs such that energization to any of the metal catalyst carriers is interrupted, the other metal catalyst carriers are energized, which is advantageous in terms of fail-safe. There are various advantages such as the existence.

[Brief description of drawings]

FIG. 1A is a vertical sectional view of an embodiment of the present invention, and FIG.
Is a view from arrow A of (A)

2A and 2B are explanatory views of the operation of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Catalytic converter device 2 Metal shell 3-5 Metal catalyst carrier 6-11 Electrode member 12-14 Mat member 15-20 Electric insulating member 21,22 Radiating plate 23-28 Nut 29,30 Flange

Claims (1)

[Claims] 1. A catalyst converter for exhaust gas purification, which is provided in an exhaust passage of an internal combustion engine and has a heater function by energizing and heating a metal catalyst carrier carrying a catalyst, wherein a plurality of metal catalysts are provided. A carrier is provided in the shell, positive and negative electrode members connected to each metal catalyst carrier are projected through the metal shell wall in an insulated state, and each positive electrode member and each negative electrode member are respectively made of a conductive material. An exhaust gas purification catalytic converter device having a structure in which metal catalyst carriers are electrically connected in parallel via a heat radiating plate.