JPH03188925A - Apparatus for cleaning waste gas - Google Patents

Abstract

PURPOSE:To achieve uniform cleaning performance by changing a pitch with of waves under same wave height of a waving strip from small to large in the direction from starting tip side to end tip side of coiling in the strip constituting a honeycomb body. CONSTITUTION:A waste gas cleaning apparatus A is constituted with the honeycomb body 1 for supporting a cleaning catalyst having plural net-like gas venting paths 13 in axial direction manufactured by coil-laminating a flat-state strip 11 and waving strip 12 of strip metals. Then, the waving strip 12 is made to have the same wave height H and change its pitch width of the wave from small to large in the direction from the starting tip side to the end tip side of winding. In this result, as cell density can be made so as to continuously vary, the uniform cleaning performance can be obtd. even under variation in flow speed distribution of the waste gas stream passing through the honeycomb body.

Description

[Detailed Description of the Invention] "Objective of the Invention" (Industrial Application Field) The present invention is directed to supporting an exhaust gas purifying catalyst, which is generally inserted in the middle of an exhaust pipe as a means for purifying automobile exhaust gas. This invention relates to an exhaust gas purification device consisting of a metal two-cam body.

More specifically, the present invention provides an exhaust gas purification system in which the amount of supported exhaust gas purification catalyst is adapted to differences in flow velocity distribution of exhaust gas flow within an exhaust gas purification device, thereby achieving uniform purification performance. The purpose is to provide a purification device.

(Prior Art) Conventionally, this type of exhaust gas purification device has a flat band made of a heat-resistant thin steel plate and a corrugated band formed by corrugating the thin steel plate, so that they have an abutting portion with each other. A honeycomb-like laminated body (hereinafter referred to as a honeycomb body) having a large number of mesh-like ventilation holes for exhaust gas passages in the axial direction, which is manufactured by stacking the two layers together and stacking them in a spiral shape. , is composed of a cylindrical metal case with both ends open for loading and fixing the honeycomb body. It goes without saying that the exhaust gas purifying catalyst is supported on the wall surface of the honeycomb body.

The honeycomb body and the metal case are designed to withstand thermal expansion and thermal stress caused by the high temperature of the exhaust gas itself, the exothermic reaction between the exhaust gas and the purification catalyst, and to withstand vibrations when the vehicle is running. It is firmly fixed by soldering etc. It goes without saying that the abutting portions of the flat band material and the corrugated band material constituting the honeycomb body may be fixed by various methods.

Furthermore, recently, in order to compete with the conventional cordierite-based ceramic carriers in price, there has been a movement toward constructing exhaust gas purification devices without using a metal case, that is, with only metal honeycomb bodies. In this case, since a metal case is not used, the manufacturing cost of the metal case, and the cost of loading and fixing the metal case and the metal honeycomb body.

Needless to say, so-called canning costs are reduced, resulting in significant cost benefits.

(Problems to be Solved by the Invention) However, in conventional exhaust gas purification devices that are constructed only of the honeycomb body or that are constructed of a honeycomb body and a metal case, uniform purification of exhaust gas is expected. Can not do it.

This is because in conventional exhaust gas purification devices, the corrugated strips forming the honeycomb body have the same wave height (H) and the same wave pitch width (P). It is. That is, in this type of exhaust gas purification device, the exhaust gas has different flow velocity distributions at the axial center (center) of the honeycomb body and at its outer periphery (the former is larger). Conventional exhaust gas purification devices in which the cells formed by the corrugated strips have the same density cannot achieve thorough and uniform exhaust gas purification. In addition, once the reaction between the exhaust gas and the purification catalyst starts, the axial center (center) of the honeycomb body has a higher flow rate of exhaust gas and the heat generated by the catalytic reaction, causing the catalyst to react more rapidly than in other parts. Since the reaction is activated, a significant difference in the degree of purification occurs.

To solve this problem, methods have been disclosed in Utility Model Application No. 62-158116 and Japanese Patent Application Laid-open No. 62-174525 that take into consideration the shape of the corrugated sheet and the thickness of the flat sheet, but these methods lead to high costs and uniformity. This is problematic in terms of its ability to purify exhaust gas.

In addition, Japanese Patent Application Laid-open No. 1-274844 discloses a method in which the channel cross section (channel diameter) increases as the radial distance from the central axis increases, and more specifically, both the pitch width and wave height of the corrugated sheet. Disclosed is a device that simultaneously changes from small to large. However, in devices where the wave pitch width and wave height are changed at the same time, the exhaust gas flow path (cell) formed by the flat plate and the corrugated plate becomes very small in the center, or in other words, the cell density If it becomes too large, there will be negative effects. For example, if the cell density becomes too large, the pressure drop of the exhaust gas will increase (decreased engine efficiency), and the temperature in the center will become too high as a result of the cell density becoming too large. There are disadvantages such as applying thermal stress (reduced lifespan).

In addition, from the aspect of manufacturing the honeycomb body, the number of turns of the flat plate and the corrugated plate is increased compared to the conventional one, resulting in a decrease in productivity.

The present inventor conducted extensive studies in view of the drawbacks of the conventional exhaust gas purification apparatus described above. As a result, among the strip materials constituting the honeycomb body, the wave pitch width (P) of the corrugated strip material changes gradually under the same wave height (H) from the winding start end to the winding end. They have found that this is extremely effective and have completed the present invention.

"Structure of the Invention" (Means for Solving the Problems) To summarize the present invention, the present invention provides a structure in which a flat strip and a corrugated strip of thin metal plates are piled up so as to be in contact with each other. In an exhaust gas purification device using a honeycomb body for supporting an exhaust gas purification catalyst having a large number of mesh-like vent passages in the axial direction and manufactured by winding and stacking this in a spiral shape, The present invention relates to an exhaust gas purification device, characterized in that the corrugated strip has the same wave height (H), and the wave pitch width (P) changes from small to large from the winding start end to the winding end. It is something.

(Example) Hereinafter, the configuration and examples of the present invention will be described in detail based on the drawings.

FIG. 1 is a schematic sectional view for explaining the characteristic parts of the exhaust gas purification device fA) of the present invention, and FIG. 2 is a sectional view showing the waveform of the corrugated band material (12).

The exhaust gas purification device (Al) of the present invention consists of stacking a flat strip material (11) and a corrugated strip material (12) so that they are in contact with each other, as shown in FIG. It is constructed using a honeycomb body fl) that is laminated to form a honeycomb body fl). A large number of vent channels (cells) that serve as passages for exhaust gas are created by winding and laminating the flat strip material fill and the corrugated strip material (12).
f131 is automatically formed.

As the flat strip material, for example, Fe-Cr2O%-A°C
5% heat-resistant stainless steel, or heat-resistant stainless steel with rare earth elements added to it to improve oxidation resistance, with a thickness of 0.04 mm and a width of 75 mm, and as corrugated strip material. The flat strip material processed into a corrugated shape is used. When stainless steel containing 1 is used for each strip material, whisker-like AJ22 is formed on the surface of the strip material by heat treatment.
03 is precipitated, which is preferable because it firmly supports the exhaust gas purifying catalyst.

It goes without saying that in the present invention, although not shown in the drawings, the honeycomb body (11) may be loaded into a cylindrical metal case and fixed thereto to form an exhaust gas purification device.

In addition, in the present invention, in order to effectively absorb and alleviate the deformation force based on the large thermal stress applied to the L-plate-shaped strip and the corrugated strip that constitute the honeycomb body, the flat-shaped strip As the waveform, a waveform having a pitch width and wave height smaller than the waveform of the corrugated band material can be adopted.

A major feature of the present invention is that the corrugated band material (12), which is a member constituting the honeycomb body (1), uses a material whose waveform shape is shown in FIG. 2.

That is, this type of honeycomb body usually has a wave height of 0.5 to 3.
A uniformly corrugated strip with the same wave height and pitch width of about 1.0 to 6.0 mm and pitch width is used, but in the present invention, as shown in the figure,
Under H), the pitch width P is continuously from small (minimum) to large (maximum) from the starting end of the winding with the flat strip material to the end of the winding.
It is characterized by the use of materials that change.

In the present invention, the corrugated band material (12) shown in FIG. 3 may be used. FIG. 3 is a cross-sectional view showing the waveform of a corrugated band material. The difference from that in FIG. 2 is that the pitch width P from small (minimum) to large (maximum) (third
In the case of the figure, the relationship p, < p2 < p3 is shown. ).

In the present invention, the corrugated strip material 2) and the honeycomb body (1) described above may be manufactured in a desired manner.

For example, a corrugated sheet material of a predetermined length is manufactured using a plurality of corrugating rollers that can corrugate the same wave height but with different pitch widths, and then the corrugated sheet material is sequentially increased in pitch width. They may be connected in a manner similar to each other, and may be rolled and laminated with a flat strip material. Also, by connecting these multiple corrugated rollers in series,
It is also possible to continuously produce corrugated strips having the same wave height but with pitch widths that sequentially change from small to large, and to wind and stack these strips with a flat strip. Furthermore, even if a single corrugated roller is used to continuously produce corrugated strips with the same wave height but a pitch width that sequentially changes from small to large, this can be rolled and laminated with a flat strip. good.

As described above, the exhaust gas purification device fA) of the present invention can vary the wave pitch width (P) from small (minimum) to large (maximum) under the same wave height (H) as the flat band material fil). Since the honeycomb body (fl) is manufactured by winding and laminating the corrugated strip material (I2) having a waveform that changes in The formation density of the pore channels (131 (cells) is relatively larger than that in other parts, and the mesh-like vent channel f13 at the outer periphery (end of winding) of the honeycomb body
) (cells) are characterized by a low density of formation. As a result, the contact reaction between the exhaust gas and the catalyst is made uniform under the difference in the flow velocity distribution of the exhaust gas flow within the exhaust gas purification device iAl (maximum at the axial center and minimum at the outer periphery). Uniform exhaust gas purification is achieved. In the present invention, this is achieved by an extremely simple means of forming the corrugated strip material (12) into the shape described above.

1 [Effects of the Invention 1] The present invention provides a honeycomb body, which is a wound laminate of a flat strip material and a corrugated strip material constituting an exhaust gas purification device, at the same wave height (H) as the corrugated strip material. ) is the wave pitch width (P)
Since the winding is manufactured using a material that varies from the minimum to the maximum from the winding start end to the winding end, an exhaust gas purification device that exhibits the following excellent effects can be economically provided.

(i) Corresponding to the flow velocity distribution of exhaust gas, the formation density of mesh-like vent passages (cells) in the axial center (center of winding) of the honeycomb body is relatively large compared to other parts. In addition, a mesh-like ventilation hole channel (
The cell density can be changed continuously or stepwise so that the formation density of cells (cells) becomes small, so even if the flow velocity distribution of the exhaust gas flow passing through the honeycomb body is different, it is uniform. It is possible to achieve a high purification ability.

(iii) Compared to the conventional wave height (H) and pitch width 2 (P), the amount of supported catalyst can be optimized according to the flow velocity distribution of the exhaust gas. Wasteful use of catalyst can be eliminated and expensive catalysts can be saved.

Since back pressure is not increased, engine efficiency is not reduced.

Since the fiv1 corrugated strip material has the same wave height as the conventional material (however, the pitch width is different), the honeycomb body can be manufactured with the same number of windings without reducing productivity.

fV) Compared to the case in which the central region of the honeycomb body is composed of corrugated strips having a smaller pitch width and wave height than the present invention, the wave of the corrugated strip joined to the flat strip is Since the distance between the peaks (or between the valleys) is large, the deformation force due to thermal stress can be absorbed and alleviated in the region between the junction points, and the life of the exhaust gas purification device can be increased.

(vi1 The center part of the winding has a rigid structure, and the end part of the winding has a flexible structure, so it is easy to absorb mechanical impact force.

(vii) When fixing the abutting portions of the flat strip material and the corrugated strip material, since the pitch width P of the waves is larger at the contact point near the outer periphery of the honeycomb body, the contact point near the outer periphery of the honeycomb body has a larger pitch width P than the point bonding at the center. This makes the bond strong. Therefore, both strips do not peel off due to loads of thermal stress or vibration force, and damage and cracks in both strips that are promoted after peeling are effectively prevented.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the exhaust gas purification device of the present invention. FIG. 2 is a cross-sectional view of a corrugated strip showing one aspect of the waveform, and FIG. 3 is a cross-sectional view of the corrugated strip showing another aspect of the waveform. A...... Exhaust gas purification device 1...
...honeycomb body 11 ... flat strip material 12 ... corrugated strip material 3 ... mesh ventilation hole path ■] wave height P ... ... wave pitch width patent Applicant Usui Kokusai Sangyo Co., Ltd. Agent

Claims (1)

[Claims] 1. Supporting an exhaust gas purifying catalyst having a large number of mesh-like ventilation holes in the axial direction, which is manufactured by winding and laminating thin metal plate flat strips and corrugated strips. In an exhaust gas purification device consisting of a honeycomb body for the purpose of
An exhaust gas purification device characterized in that the amount changes from small to large. 2. The exhaust gas purification device according to claim 1, wherein the pitch width P of the corrugated band material changes stepwise from small to large. 3. The exhaust gas purification device according to claim 1, wherein the pitch width P of the corrugated band material continuously changes from small to large. 4. The exhaust gas purification device according to claim 1, wherein the flat band material has a waveform smaller than that of the corrugated band material. 5. The exhaust gas purification device according to claim 1, wherein the honeycomb body is fixed within a cylindrical metal case.