JPH04103819A - Exhaust gas purification device - Google Patents

Abstract

PURPOSE:To secure exhaust gas purification ability with high level by composing a front stage of a spiral, involute, and S-shaped honeycomb body in the flowing direction of exhaust gas, composing a rear stage of a wound honeycomb body, and thereby obtaining even contact and reaction of the exhaust gas and catalyst. CONSTITUTION:A rear-stage honeycomb body composing an exhaust gas purification device is a honeycomb body IH made by winding the lamination of a plate-like band 11 and a waved band 12. A spiral honeycomb body 2H, an involute honeycomb body 3H, and an S-shaped honeycomb body 4H which are used in the front stage of the wound honeycomb body 1H have, in view of their characteristics of form, better ability for equalizing velocity distribution of exhaust gas compared to the wound honeycomb body 1H. The even contact and reaction of the exhaust gas and carried catalyst is obtained further on the wound honeycomb portion.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Industrial Application Field) The present invention relates to an exhaust gas purifying device which is used by being inserted in the middle of an exhaust pipe as a means for purifying exhaust gas of an automobile. The present invention relates to an exhaust gas purification device comprising a metal honeycomb body for supporting a catalyst.

More specifically, the combination method of the flat strip material and the corrugated strip material constituting the honeycomb body is combined so that the flow velocity distribution when the exhaust gas passes through the inside of the honeycomb body is uniform, and the inside of the honeycomb body is This relates to an exhaust gas purification device that eliminates uneven catalytic reactions and heat spots based on uneven flow velocity.

(Prior Art) Conventionally, this type of exhaust gas purification device generally has a thickness of 0-0.
A flat strip of heat-resistant thin steel plate of 3 to O, 1 mm and a corrugated strip made of the thin steel plate are stacked so that they have abutting portions, and this is depleted. A honeycomb-like laminate (hereinafter referred to as a "wound honeycomb body") having a large number of mesh-like ventilation holes (cells) for exhaust gas passages in the axial direction, which is manufactured by winding and laminating the above-mentioned It consists of a cylindrical metal case with open ends for enclosing and fixing a wound honeycomb body. It goes without saying that an exhaust gas purifying catalyst (PT, Pd, Rh, etc.) is supported on the wall surface of the honeycomb body.

The above-mentioned wound type henicam body and metal case are designed to withstand thermal expansion and thermal stress caused by the high temperature of the exhaust gas itself and the exothermic reaction between the exhaust gas and the purification catalyst, It is firmly fixed by soldering etc. to withstand vibrations during driving. On the other hand, the abutting portions of the flat band material and the corrugated band material constituting the honeycomb body are fixed by various methods.

However, the above-described exhaust gas purification device composed of a wound honeycomb body and a metal case leaves room for improvement from the viewpoint of sufficient reaction between the exhaust gas and the catalyst.

The above-described wound honeycomb body is easy to manufacture, and has excellent fixing strength and ease of fixing (brazing) the abutting portions of the flat strip material and the corrugated strip material constituting the honeycomb body. However, the uneven flow velocity distribution of exhaust gas in the exhaust system (
In a cylindrical exhaust pipe, the center has the maximum flow velocity. ), the catalytic reaction becomes non-uniform, and due to the non-uniform catalytic reaction, heat spots (local high temperature in the center of the honeycomb body) occur inside the honeycomb body, as well as local thermal stress distortion. Occurrence, etc. occur.

(Problems to be Solved by the Invention) The present inventors have made extensive studies to eliminate the drawbacks of the wound honeycomb body described above. As a result, the metal honeycomb body applied to the exhaust gas purification device Instead of using a single structure, a radial, expanded, or S-shaped honeycomb body, which is superior in terms of making the flow velocity distribution of exhaust gas more uniform, is placed in front of the wound honeycomb body. The inventors have discovered that the contact reaction between the exhaust gas and the supported catalyst at the wound honeycomb body portion can be made more uniform by providing the above structure, 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 honeycomb formed of a flat strip material and a corrugated strip material for supporting an exhaust gas purifying catalyst. In the exhaust gas purification device having a body, the honeycomb body, when viewed in the flow direction of the exhaust gas, (i) has a front stage formed in a radial shape, an extended line shape, or a figure 8 shape, and (ii) a rear stage. The present invention relates to an exhaust gas purification device characterized in that a portion thereof is formed in a wound shape.

Hereinafter, the configuration and embodiments of the present invention will be explained in more detail based on the drawings. Note that the present invention is not limited to what is shown in the drawings, and these things should be understood as illustrative.

The latter-stage honeycomb body constituting the exhaust gas purification device of the present invention is made by stacking flat strips (11) and corrugated strips 2), as shown in FIG. A rolled honeycomb body (1 old) is manufactured by winding and laminating the rolled honeycomb body (1 old). Although the casing (2) is not particularly required, it is not necessary to use the flat strip (11) and the corrugated strip (11).
When 2) are arranged so as to abut each other, a large number of mesh-like vent channels 3) (cells), which serve as passages for exhaust gas, are automatically formed.

As the flat strip material, for example, Fe-Cr2O%-+1
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. A for each strip material! When stainless steel containing aluminum is used, whisker-like Al2 is formed on the surface of the strip by heat treatment.
203 is precipitated, which is preferable because it firmly supports the exhaust gas purifying catalyst.

For example, the wound honeycomb body is manufactured as follows.

(a) Flat strip material Cr2O%, A! 5% heat resistant steel thickness 0.05mm.

A metal strip material with a width of 75 mm was used.

(b) Corrugated strip material Made of the same type of heat-resistant steel as the flat strip material, using a - set of forming gears, the pitch width of the ridges is 3.5 mm, and the height of the ridges is 1.8 mm. We made corrugated metal strips.

The flat strip material and the corrugated strip material are stacked on top of each other, and then -
A honeycomb body with an outer diameter of 70 mm was manufactured by winding and laminating the material in a depleted spiral shape.

Next, the above-mentioned wound honeycomb body (radial honeycomb body f2H disposed in the previous stage of the previous stage) which is the greatest feature of the present invention.
, an expanded linear honeycomb body (3H), and an S-shaped honeycomb body (4H) will be explained.

Fig. 2 is a front view of the radial honeycomb body (2H) used in the present invention.The radial honeycomb body (2H) is made of the same type of heat-resistant thin steel plate as the wound honeycomb body (IH). As shown in Fig. 2, flat strips 1ll) are arranged radially from the center fc) so as to have, for example, a central angle a. Corrugated sheet material (1
2) can be manufactured by inserting and fixing.

Figure 3 shows the expanded linear honeycomb body (3) used in the present invention.
It is an old front view. The expanded honeycomb body (3H) is also manufactured using the same kind of heat-resistant thin steel plate as the wound honeycomb body (1 old). Flat strip material (11) so that the stretch line extends
It is manufactured by expanding and opening a desired number of elements fEl consisting of a corrugated strip material (12) and a corrugated strip material (12).

Fig. 4 is a front view of the S-shaped honeycomb body (4H) used in the present invention. For example, flat strips (11) and corrugated strips (12) are stacked alternately in a layered manner. With the fixed points (3, 4) as the center, each of the elements fEl consisting of the flat strip material and the corrugated strip material is oriented in opposite directions about the two fixed points (3, 4). It is manufactured by bending it.

In the present invention, the radial honeycomb body (2H), the expanded linear honeycomb body (3H), and the S-shaped honeycomb body (4
The old type is superior in terms of uniformizing the flow velocity distribution of exhaust gas than the old type due to the shape characteristics of its structure.
~4) In 1), if a communication hole is provided in the wall of the corrugated strip material (12) so as to communicate from the center of the honeycomb body to the outer circumference of the honeycomb body, the exhaust pipe system Since the exhaust gas having the maximum flow velocity in the center of the honeycomb body is guided to the outer periphery of the honeycomb body, the flow velocity distribution of the exhaust gas flow is further improved.

(Example) The exhaust gas purification device of the present invention is constructed by arranging the honeycomb bodies (2H to 4H) having the specific structure described above in the front stage and the wound honeycomb body H) in the rear stage. Ru. For example, a honeycomb body (2) with different types of arrangement as shown in Figure 5.
Exhaust gas purification device f by using [, I) r)
A) is configured.

In the exhaust gas purification device fA) shown in FIG.
When viewed in the flow direction of exhaust gas, a radial honeycomb body (2H) is used in the front stage and a wound honeycomb body (1■) is used in the rear stage, but instead of the radial honeycomb body (2H),
Expanded linear honeycomb body (3H) or S-shaped honeycomb body (
It goes without saying that 4H) may also be used.

In the present invention, the honeycomb body (21 (- 41 () is a wound honeycomb body fl
The width of the honeycomb body in the front stage (
l) is preferably smaller than the width (L) of the wound honeycomb body (1) at the rear stage.For example, ρ=I-/10~L
A width of /3 is sufficient. Further, as shown in FIG. 5, a width of a mixing space C for mixing the exhaust gas flow between the front honeycomb body (2H to 411) and the rear winding honeycomb body (IH), W) may be provided to further reduce ρ.

[Effects of the Invention] In the exhaust gas purification device of the present invention, the front stage is composed of a radial, expanded linear, or S-shaped honeycomb body, and the rear stage is composed of a wound honeycomb body, as viewed in the flow direction of exhaust gas. It is made up of the body. Since the exhaust gas purification device is configured with different types of honeycomb bodies in this way, it has the following excellent functions and effects; This makes the uneven flow velocity distribution of the exhaust gas flow more uniform. As a result, the overall exhaust gas purification system achieves a more uniform catalytic reaction between the exhaust gas and the supported catalyst than the conventional single honeycomb structure, resulting in a high level of exhaust gas purification performance. Secured.

[ii) In relation to the effect of fi) above, the large thermal stress strain that was locally generated in the center of the conventional honeycomb can be dispersed throughout the device, and the durability of the entire device can be improved. can.

fiii) The honeycomb body with the specific structure of the front stage part has the above-mentioned (i)
In addition to the function of uniformizing the flow velocity distribution of the exhaust gas flow, it can also function as a pre-catalyzer (exhaust gas preliminary reactor). Since it is possible to control the optimal temperature conditions for the catalytic reaction in the honeycomb body, the exhaust gas purification ability of the entire device can be improved. For example, by allowing the catalyst supporting wall on the pre-catalyzer side to support a larger amount of catalyst per unit area than the main catalytic converter in the rear stage,
The effects described above can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a front view of a wound honeycomb body used in the latter part of the exhaust gas purification device of the present invention. FIG. 2 is a schematic front view of a radial honeycomb body used in the front stage of the exhaust gas purification device of the present invention. FIG. 3 is a schematic front view of an expanded honeycomb body used in the front stage of the exhaust gas purification device of the present invention. FIG. 4 is a schematic front view of an S-shaped honeycomb body used in the front stage of the exhaust gas purification device of the present invention. FIG. 5 is an axial cross-sectional view of the exhaust gas purification device of the present invention. A...Exhaust gas purification device IH, 2H, 3H, 4H...Honeycomb body 11...Flat strip material 12...Corrugated strip material 13...Mesh ventilation hole path

Claims (7)

[Claims] 1. In an exhaust gas purification device having a honeycomb body formed of a flat strip material and a corrugated strip material for supporting an exhaust gas purification catalyst, the honeycomb body has (i) An exhaust gas purification device characterized in that: (i) the front stage part is composed of a radial, stretched linear, or S-shaped part, and (ii) the rear stage part is composed of a coiled part. . 2. Claim 1, wherein the front honeycomb body and the rear honeycomb body are arranged in close contact with each other or at a predetermined distance apart.
Exhaust gas purification device as described in section. 3. 2. The exhaust gas purification device according to claim 1, wherein the width of the front honeycomb body is equal to or less than the width of the rear honeycomb body. 4. The exhaust gas purification according to claim 3, wherein the width (l) of the front honeycomb body has a relationship of l=L/10 to L/3 with respect to the width (L) of the rear honeycomb body. Device. 5. The honeycomb body at the front stage is a radial structure in which corrugated strips with waveforms that gradually increase in size from the center to the outer periphery are fixed between flat strips arranged radially from the center of the honeycomb body. The exhaust gas purification device according to claim 1, which is an exhaust gas purification device. 6. The honeycomb body in the front stage is an expanded type in which a desired number of purifying elements made of flat strips and corrugated strips are extended outward in an expanding line from the center of the honeycomb body. An exhaust gas purification device according to claim 1. 7. The honeycomb body in the front section bends a laminate in which flat strips and corrugated strips are alternately stacked in opposite directions around at least two fixing points set on the surface of the laminate. 2. The exhaust gas purification device according to claim 1, wherein the exhaust gas purification device is formed into an S-shape obtained by processing and bending the flat plate-like band material and the corrugated band material into an S-shape.