JPH04342819A - Catalyst carrier for internal combustion engine - Google Patents

Abstract

PURPOSE:To enhance the efficiency of contact between exhaust gas and catalyst by roughening the wall surface of numeral micro flow passages. CONSTITUTION:Metal mesh plates 1 having several openings 4 which are parted from each other by line segments 5, are laminated one upon another, being slightly shifted from each other. The lamination of the openings 4 defines micro passages which meanders, having step-like wall passages.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal catalyst carrier used for purifying the exhaust gas of an internal combustion engine, and particularly to a catalyst carrier suitable for a catalytic converter of a diesel engine.

0002

[Prior Art] A catalyst carrier used in a catalytic converter for an internal combustion engine is a ceramic carrier in which a large number of honeycomb-shaped channels are formed in a ceramic block (for example,
1-78215, etc.), and a metal carrier made by stacking a flat metal plate and a corrugated metal plate and winding them into a cylindrical shape to form a large number of fine flow channels (for example, Showa 63
-63521, etc.). In general, a metal carrier has a smaller heat capacity, so it has the advantage of being superior in temperature rise characteristics after the engine is started.

0003

[Problems to be Solved by the Invention] However, in any of the above conventional catalyst carriers, fine flow channels are formed substantially linearly along the exhaust flow direction, and the exhaust gas flows through each flow channel. Because the flow is relatively rectified along the road wall surface, the contact efficiency between the exhaust gas and the catalyst is not necessarily high, and in order to obtain sufficient catalytic action, the flow path length must be long. I don't get it. In other words, the catalyst carrier becomes larger.

[0004] In the above-mentioned Japanese Utility Model Application Publication No. 61-78215 and Japanese Utility Model Application Publication No. 63-63521, the contact efficiency is increased by forming each flow path with a slight bend.
Basically, the exhaust gas just flows along the wall surface of the flow path, and the efficiency of contact with the catalyst does not improve much.

[0005]

[Means for Solving the Problems] A catalyst carrier for an internal combustion engine according to the present invention includes a mesh-like metal plate in which a large number of openings are opened leaving a line portion having a substantially rectangular cross section, and each opening is surrounded by a mesh metal plate. It is characterized by laminating a plurality of sheets with the opening positions slightly shifted so that the wires partially overlap around the entire circumference of the opening, and the outer periphery is fixed and held by a cylindrical frame. .

[0006]

[Operation] In the above structure, a large number of fine flow paths communicating between the front and back of the carrier are formed by each opening in the plurality of laminated mesh metal plates. Since the opening positions of each metal plate are slightly shifted from each other, this fine flow path becomes a complicatedly curved flow path. In particular, because the lines of each metal plate are lined up with slight deviations, the channel wall surface becomes uneven and stepped, increasing the contact area with the exhaust gas and causing the exhaust gas to collide with each stage and repeat its diffusion. flow, and the contact efficiency with the catalyst is increased.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 2 is a perspective view showing the external appearance of the catalyst carrier according to the present invention, and as shown in FIG. This is inserted into a metal frame 2 having a rectangular cylindrical shape, and the opening edge 2a of the frame 2 is caulked inward to be fixed integrally.

[0009] This catalyst carrier supports the catalyst with a coating of ceramics containing a catalyst metal, and is housed in a casing (not shown), and is interposed in the exhaust system of an internal combustion engine. ing.

The mesh metal plate 1 has a plurality of slits 3 alternately formed in a base material 1' made of a thin metal plate, as shown in FIG. 4, for example.
It is stretched in the -A direction to form a rhombic lattice shape as shown in detail in FIG. In other words, a large number of diamond-shaped openings 4 are open leaving only the line portions 5. The opening 4 has a size of, for example, about 1 to 2 mm on one side. Further, as shown in FIG. 5, the line portion 5 has a substantially rectangular cross-sectional shape. Note that a similar mesh shape may be formed by punching a large number of openings in a flat metal plate.

[0011] The mesh metal plates 1 described above are stacked one after another with the positions of the openings 4 slightly shifted. In particular, as shown in FIG. 1, the line portion 5 of a certain mesh metal plate 1 is shifted within the range where the line portion 5 of an adjacent mesh metal plate 1 partially overlaps the entire circumference of the opening 4. They are stacked in a stacked state. As a result, a continuous fine channel 6 is formed inside the opening 4 (see FIG. 5), and as each mesh metal plate 1 is displaced, the minute channel 6 becomes gradually curved. In addition, when stacking with slight shifts, the direction of the shifts may be aligned in one direction, but preferably,
As shown in FIG.
It is better to make it curve in a complicated way.

In the catalyst carrier having the above structure, exhaust gas is introduced from a direction perpendicular to the mesh metal plate 1 and passes through a large number of fine channels 6. Here, each microchannel 6 is complicatedly curved, and in particular, the channel wall surface has a step-like shape due to the line portions 5 located slightly shifted from each other, so that the contact area between the exhaust gas and the channel wall surface increases. At the same time, as shown by arrows in FIG. 5, the exhaust gas collides with step-like unevenness and diffuses, and the collision repeats many times. Therefore, the contact efficiency between the catalyst on the surface of the wire portion 5 and the exhaust gas is improved, and the conversion efficiency of CO, HC, etc. by the catalyst is improved.

In particular, when the catalyst carrier having the above structure is applied to a diesel engine, SOF, which is a part of the exhaust particulates,
In addition to being able to significantly reduce the amount of organic components (soluble organic components) through catalytic action, when the exhaust flow rate is low and the load is low, it also has the effect of adhering and collecting carbon and other exhaust particulates to some extent, suppressing the generation of black smoke. be.

[0014] Furthermore, since the catalyst carrier is made of metal,
It has a small heat capacity and excellent temperature rise characteristics.

In the above structure, the wire portions 5 of the mesh metal plates 1 partially overlap each other around the entire circumference of the opening 4, but if the wire portions 5 of the mesh metal plates 1 overlap each other over the entire circumference of the opening 4, 1
If it is shifted, a gap 7 will be created between each line portion 5 as shown in FIG. 6, and this will eventually become clogged with Ash components 8 (oxides of oil additives, etc.) that cannot be removed by combustion. , there is a problem in that the effective cross-sectional area of the flow path gradually decreases, leading to an increase in pressure loss. On the other hand, if the line portions 5 are densely stacked as in the above configuration, the Ash component will be difficult to accumulate at the corners.

Next, FIG. 7 shows an embodiment in which the catalyst carrier has a cylindrical shape, in which a plurality of mesh metal plates 1 are formed in a circular shape, and these are densely stacked. It is inserted into the manufactured frame 2. The opening edges 2a of the frame 2 are caulked inward to be fixed together.

Although the catalyst carrier described above is suitable for diesel engines as described above, it is not necessarily limited thereto, and can naturally be applied to gasoline engines as well.

[0018]

[Effects of the Invention] As is clear from the above explanation, according to the catalyst carrier for an internal combustion engine according to the present invention, a large number of fine flow channels can be set in a freely curved manner depending on the way the mesh metal plates are stacked. This makes it possible to prevent exhaust gas from passing through like in the past. In particular, because the lines of each metal plate are lined up slightly offset, the channel wall surface becomes uneven and stepped, increasing the contact area with the exhaust gas, and causing repeated collisions and diffusion of the exhaust gas, leading to contact with the catalyst. The efficiency is extremely high.

[Brief explanation of the drawing]

FIG. 1 is an enlarged plan view of main parts showing two mesh metal plates stacked one on top of the other.

FIG. 2 is an external perspective view showing the overall structure of the catalyst carrier.

FIG. 3 is a cross-sectional view of its main parts.

FIG. 4 is an explanatory diagram showing an example of a method for forming a mesh metal plate.

FIG. 5 is a sectional view of a main part in a state in which a large number of mesh metal plates are laminated.

FIG. 6 is a cross-sectional view of the main parts of a comparative example in which the lines are shifted so that gaps are created between them.

FIG. 7 is a perspective view showing an example in which the catalyst carrier is formed into a cylindrical shape.

[Explanation of symbols] 1...Mesh metal plate 2...Frame 4...Opening 5... Line part 6...Minute channel

Claims (1)

[Claims] [Claim 1] A mesh-like metal plate formed by a large number of openings leaving a line portion with a substantially rectangular cross section, the line portion surrounding each opening partially overlapping the entire circumference of the opening. A catalyst carrier for an internal combustion engine, characterized in that a plurality of catalyst carriers are stacked with opening positions slightly shifted, and the outer peripheral part is fixed and held by a cylindrical frame.