JP2002089252A - Exhaust emission control device for internal combustion engine, its manufacturing method and holding material of carrier for exhaust emission control - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compensate deterioration of bearing pressure in a burning process of organic substance included in a non-expansive holding member using alumina fiber or the like as a matrix and to prevent deviation of a carrier installation position. SOLUTION: An expanding material expandable at comparatively low temperature is included in at least a part of the holding material 31. When forming a container material 41' by spinning work, the expanding material (vermiculite, graphite or the like) expanded by heat generated by the spinning work is included in a side facing the container material 41'. It is also favorable to include the expanding material in a side facing a carrier 11.

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 apparatus for an internal combustion engine, a method for manufacturing the same, and a holding material for an exhaust gas purifying carrier suitable for implementing the method. More specifically, when a carrier is held inside a container using a holding material molded using an organic material, a carrier holding technology for compensating for a temporary lack of holding power during the burning process of the organic material. Regarding improvements.

[0002]

2. Description of the Related Art In response to a request based on emission regulations in recent years,
For the carrier constituting the exhaust gas purification device of the internal combustion engine,
In order to realize early activation and the like, it is necessary to have a very thin wall structure. As a holding material for holding such a thin-walled carrier inside the container, a so-called non-expandable holding material is proposed, which is formed by coating alumina fiber as a base material with an organic substance such as polyethylene. Have been.

[0003] This is generally in the form of a sheet or mat, and is inserted into a cylindrical container while being wound around the outer periphery of the carrier. The inlet and outlet of the container are reduced in diameter by spinning or the like, and the exhaust gas purifying apparatus is commercialized. Conventionally,
As such a manufacturing method, JP-A-2000-16105
There is one disclosed in Japanese Patent Application Laid-Open Publication No. 1 (1999) -86.

[0004]

However, the conventional holding material has the following problems. In other words, in this case, when the holding material is wound around the carrier and placed inside the container, the organic material for maintaining the holding material in a compressed state covers the surface of the holding material. The heat generated when the diameter is reduced by spinning,
Organic substances are thermally decomposed. Then, during the period until the melted organic substance is completely burned out and the surface pressure recovers, the surface pressure of the holding material temporarily decreases to a surface pressure necessary to hold the carrier, and the pressure during processing is reduced. The carrier installation position may be displaced by vibration or the like, which may lead to damage of the carrier itself.

[0005] A similar problem may occur after commercialization. Organic substances that have not been thermally decomposed by the heat generated during spinning (especially on the contact surface side with the carrier)
This is because during initial operation of a new vehicle, it is thermally decomposed by receiving heat from exhaust gas, and a similar decrease in surface pressure occurs. In view of such a situation, the present invention makes it possible to always obtain a surface pressure equal to or higher than a required surface pressure by compensating for a decrease in surface pressure in the process of burning out the organic substance contained in the holding material by a simple method, An object of the present invention is to provide an exhaust gas purifying apparatus for an internal combustion engine and a method for manufacturing the same, and a holding material for an exhaust gas purifying carrier, which can prevent the displacement of the carrier installation position as described above.

[0006]

SUMMARY OF THE INVENTION Therefore, a method of manufacturing an exhaust gas purifying apparatus for an internal combustion engine according to the present invention is characterized in that an exhaust gas purifying carrier is provided by disposing a holding material containing an organic substance on an outer periphery thereof. A method of manufacturing an exhaust gas purifying apparatus for an internal combustion engine, wherein at least a part of the carrier container is subjected to the diameter reduction. The method is performed by attaching an expanding material that expands due to heat generated during processing (claim 1).

Further, according to the method of manufacturing an exhaust gas purifying apparatus for an internal combustion engine according to the present invention, a non-expandable holding material containing an organic substance which is burned off by thermal decomposition is wound around the outer surface of the exhaust gas purifying carrier. A method for manufacturing an exhaust gas purifying apparatus for an internal combustion engine, wherein at least a part of the carrier container is reduced in diameter, wherein the holding member temporarily expands due to heat generated during the diameter reduction. It is characterized by comprising (claim 2).

The holding material is preferably a mat mainly composed of non-expandable alumina fibers. The expansion material is preferably vermiculite or graphite (claim 4). The expanding material is
It is preferable to be unevenly distributed in the vicinity of the portion where the diameter reducing process is performed (claim 5). It is preferable that the expanding material is attached to a side of the holding material facing the container (claim 6).

In the method for manufacturing an exhaust gas purifying apparatus for an internal combustion engine according to the present invention, it is preferable that an expanding material is also provided on the side of the holding material facing the carrier. The exhaust gas purifying apparatus for an internal combustion engine according to the present invention is configured such that a non-expandable holding material containing an organic substance that is burned off by thermal decomposition is wound around an outer surface of an exhaust gas purifying carrier and stored in a carrier container. An exhaust gas purifying apparatus for an internal combustion engine having at least a part reduced in diameter, wherein the holding material includes an expanding material that temporarily expands by heat generated during the diameter reducing processing. Item 8).

Preferably, the holding material is a mat mainly composed of non-expandable alumina fibers. The expanding material is preferably vermiculite or graphite (claim 10). It is preferable that the expanding material is unevenly distributed in the vicinity of the portion where the diameter reducing process is performed (claim 11).

[0011] It is preferable that the expanding material is unevenly distributed on the side facing the carrier container. The holding material for the exhaust gas purifying carrier according to the present invention is a non-expandable holding material wound around the exhaust gas purifying carrier and holding the carrier in the carrier container, and is an organic substance that is burned down by thermal decomposition. And an expanding material that temporarily expands due to heat when the diameter of the carrier container is reduced while being housed in the carrier container together with the carrier (claim 13).

It is preferable that the expanding material is unevenly distributed in a portion near the part where the diameter reducing process is performed. (Claim 14) It is preferable that the expanding material is included on a side forming a contact surface with the carrier container. (Claim 15). It is preferable that the holding material of the carrier for purifying exhaust gas according to the present invention also contains an inflating material on the side that forms a contact surface with the carrier.

[0013]

According to the first, second, eighth, and thirteenth aspects of the present invention, at least a part of the holding material containing an organic substance is provided with or contained an expanding material that expands by heat generated during diameter reduction processing. As a result, the following effects can be obtained. When the heat at the time of diameter reduction is transmitted to the holding material, the heat decomposes the organic substance contained in the holding material. Then, at this time, the surface pressure of the holding material decreases, and the holding force of the holding material itself temporarily decreases to a required value or less. Here, by adding or containing the expanding material to at least a part of the holding material according to the present invention, the shortage of the surface pressure can be compensated and the necessary holding force can be secured.

Further, by expanding the expandable material by using the heat generated during the diameter reduction processing, the expandable material can be expanded simultaneously with the processing, that is, in accordance with the decrease in the surface pressure of the holding material, without requiring a special heat source. Can be done. According to the third and ninth aspects of the present invention, a non-expandable holding material can be easily realized by using a mat mainly composed of alumina fibers.

According to the fourth and tenth aspects of the present invention, by using vermiculite or graphite as the expanding material, it is possible to compensate for a temporary shortage of surface pressure occurring until the organic substance contained in the holding material is burned out. Not only can it be performed, but also its function can be lost over time, and the original holding force of the holding material can be obtained. Claims 5, 11, 14
According to the described invention, a shortage of the surface pressure of the holding material during the diameter reduction processing can be compensated for by a small amount of the expanding material.

According to the sixth, twelfth, and fifteenth aspects of the present invention, the function of the expanding material for compensating for the insufficient surface pressure of the holding material is provided.
Notably and easily obtainable. According to the present invention, even if the organic substance between the holding material and the carrier is melted by the heat received from the exhaust gas after mounting on the vehicle, and the surface pressure at that location is reduced, this is compensated for and the carrier is compensated. The displacement of the installation position can be prevented.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. First, the structure of the exhaust gas purifying apparatus for an internal combustion engine according to the present invention will be described. FIG. 1 is a sectional view schematically showing the configuration of an exhaust gas purifying apparatus 1 for an internal combustion engine according to one embodiment of the present invention.

The carrier 11 provided in the present apparatus 1 has a substantially cylindrical outer shape, and contains therein a particulate matter (hereinafter, referred to as "PM") discharged from a diesel engine by filtration. A large number of rectilinear through spaces are formed in parallel and parallel via a porous ceramic wall 13 as small as possible. Then, each adjacent through space is alternately and completely or substantially closed to PM on the inlet side or the outlet side of the device 1 by the plugging member 15 and is directed toward the inlet side. Entrance passage 17 that opens
And an outlet passage 19 that opens toward the outlet side are formed alternately and adjacently.

Further, for example, HC, C
A catalyst layer (not shown) having an oxidation catalyst for purifying unburned components such as O as a catalyst component is provided. Exhaust gas discharged from each combustion chamber is collected in one flow path in the exhaust manifold, and guided to the exhaust gas purification device 1. When the exhaust gas flowing into the carrier passes through the carrier 11, the PM is filtered and removed by the filter function of the wall portion 13, and the catalyst layer attached to the wall portion 13 functions to remove gaseous pollutant components. Be purified. As a result, most of the PM and gaseous pollutants are removed or purified from the exhaust gas flowing into the exhaust gas purification device 1.

Here, in the case of a gasoline engine, as the exhaust gas purifying device 1, a ceramic carrier 11 having a substantially cylindrical outer shape and having a plurality of cell passages formed therein is provided.
What formed (coated) the catalyst layer containing a three-way catalyst component can be applied. And preferably, as one embodiment of the present invention, the wall thickness t of the carrier 11 is made thinner than the conventional one, and for example, t = 2 [mil] (1 [m
[il] = 25.4 [μm]), a carrier 11 having a reduced heat mass can be used.

By reducing the wall thickness t of the carrier 11 as described above, it is possible to improve the temperature rise characteristics of the catalyst during cooling. On the other hand, since the strength of the carrier 11 is reduced, it is required to appropriately manage the holding force acting on the carrier 11 via the holding material 31 when the carrier 11 is accommodated in the container 41. Therefore, the carrier 11 is held in the container 41 using a non-expandable holding material 31 capable of exhibiting a substantially constant holding force regardless of the temperature.

As the non-expandable holding material 31, Al2O
A mat mainly composed of fibers having excellent heat resistance and low thermal expansion properties (here, alumina fibers are used) such as 3 or SiO2 is used, and is wound around the outer peripheral surface of the carrier 11. It is stored in the container 41 in the state. As a result, a holding force (frictional force) acts between the outer surface of the holding material 31 and the inner surface of the container 41 and between the inner surface of the holding material 31 and the outer surface of the carrier 11, and the carrier 11 is held at a predetermined installation position. You.

Here, the holding material 31 is coated with an organic substance which can be burned off by thermal decomposition, for example, polyethylene, so that the holding material 31 maintains a compressed state during assembly. This makes it possible to insert the compressed holding material 31 together with the carrier 11 into the container 41. However, if the surface of the holding material 31, especially the side facing the container 41, is coated with such an organic substance, The surface roughness of the coated surface is reduced, and the workability of insertion (press-fitting) into the container 41 can be improved. Then, after assembling, the holding material 31
When the organic material is burned off, the holding material 31 is restored to the original thickness, and a necessary holding force is exerted between the carrier 11 and the container 41.

The container 41 has a predetermined drawing ratio r (both the outer diameter of the container before diameter reduction is φ1 and the outer diameter of the container after diameter reduction is φ2, r = φ2 / 2 / The diameter is reduced by φ1), and diffusers 21a and 21b are formed on the inlet side and the outlet side of the apparatus 1. The exhaust gas purifying apparatus 1 having such a structure is interposed downstream of the gathering portion of the exhaust passage 100 of the engine, as shown in the engine exhaust system diagram of FIG.

Next, the exhaust gas purifying apparatus 1 described above
Will be described with reference to FIGS. In the present manufacturing method, the exhaust gas purifying apparatus 1 includes (1) the carrier 1
1 and (2) the carrier unit in which the holding material 31 is wound around the carrier 11 is referred to as a container (in order to distinguish it from the container 41 after diameter reduction, the cylindrical material before diameter reduction is hereinafter referred to as “container material 41 ′”
That. ) Set inside, (3) Both ends of container material 41 'are sequentially reduced in diameter by spinning to complete.

Hereinafter, the method for manufacturing the exhaust gas purifying apparatus 1 for an internal combustion engine according to the present embodiment will be described with reference to the above items (1) to (1).
Each (3) will be described. (1) Preparation of carrier First, the carrier 11 is provided. FIG. 3 is a perspective view of the carrier 11. The carrier 11 is a so-called Molinos carrier in which the cross section of the through space is formed in a square shape, and the wall portion 13 is
In order to reduce the heat capacity of the substrate, it is formed very thin. (2) Carrier unit set Next, the holding material 31 is wound around the carrier 11, a carrier (carrier unit) with the holding material is inserted from one side of the container material 41 ', and as shown in FIG. It is arranged at a predetermined position inside.

Here, the holding member 31 and the container material 41 'will be further described. As described above, the holding material 3
1, an alumina fiber is used as a base material, and the base material is coated with an organic substance (eg, polyethylene) which can be burned off by thermal decomposition to maintain a compressed state of the base material, and is formed into a sheet or mat having a predetermined thickness. It is molded.

The coating of the organic substance is made of the holding material 3
In addition to applying a solution containing an organic substance (binder solution) to the base material, the base material may be formed by immersing the base material in the binder solution, or by vacuum-packing the base material with a bag-like thin film of the organic material. can do. The holding material 31 is made to uniformly contain an expandable material (expandable material) such as vermiculite or graphite that can be expanded at a relatively low temperature.

The container material 41 'is formed by processing a sheet-like stainless material into a cylindrical shape. First, U
After providing a letter-shaped container material and disposing the carrier unit therein, it may be joined into a cylindrical shape. (3) Spinning As shown in FIG. 5, the container material 41 'is chucked by a chucking machine 51 for spinning. Then, the diameter of the inlet portion and the outlet portion of the container material 41 ′ is sequentially reduced by the roll machine 61 at a predetermined drawing rate r, and the diffusers 21 a and 21 b of the apparatus 1 are formed.

According to the method of manufacturing the exhaust gas purifying apparatus 1 described above, the expansion of the support material 31 causes the organic material contained in the support material 31 to be burned out by the action of the expanding material contained in the support material 31. It is possible to provide the exhaust gas purifying apparatus 1 in which the holding force formed between the carrier 11 and the container 41 is prevented from temporarily dropping below the required value, and the carrier 11 is held at the correct installation position. Next, this effect will be described with reference to FIGS.

FIG. 6 schematically shows a cross section of the spinning section S and the vicinity thereof. The transmission of heat generated by the spinning section is indicated by an arrow H. FIG.
Shows the typical change in the surface pressure of the holding material 31 during the burning process of the organic substance contained in the holding material 31 when the expansion material according to the present invention is included (solid curve 1) and the conventional expansion material. This is compared with the case where it is not included (chain line curve 2).

As shown in FIG. 6, the heat generated by the spinning process is transmitted from the spinning section S to the container material 4.
It is transmitted to the holding material 31 via 1 ', and the organic substance contained therein is thermally decomposed. Here, in the conventional case not including the expanding material, during the burning process ΔT until the melted organic substance is completely burned out and the holding material 31 by the base material itself is obtained, the holding material 31 is removed. Is reduced from the initial value Po, and the required surface pressure Pr for holding the carrier 11 at a predetermined installation position cannot be temporarily maintained.

On the other hand, according to the present invention, the holding material 31
When an expansive material is contained in the burnout process ΔT, the expansive material expands within a range that is affected by the heat in the burning process ΔT, thereby compensating for a decrease in surface pressure due to thermal decomposition of the organic substance. Therefore, even if the required holding force is not obtained by the base material itself until the organic substance is completely burned off, the shortage is compensated for by the expanding material, and the required surface pressure Pr that is always required for the entire holding material 31 is reduced. Thus, the carrier 11 can be held at a predetermined installation position.

The expanding material contained in the holding material 31 expands with an expanding force that does not cause the thin-walled carrier 11 to collapse, and then loses its function with the lapse of time. The original holding power can be obtained. In addition to the above, in the above-described manufacturing method, since the expanding material is uniformly contained in the holding material 31, the expanding material is also included on the side facing the carrier 11. Here, the intumescent material that has not been burned off during the spinning process remains in the holding material 31 without being expanded even after commercialization, and the intumescent material contained in the holding material 31 without being expanded is a new vehicle. During the initial operation of, expansion occurs due to heat received from exhaust gas. Therefore, when the organic substance still contained in the holding member 31 is thermally decomposed during the initial operation, the decrease in the surface pressure of the holding member 31 can be compensated for as described above, and the displacement of the carrier installation position can be prevented.

Although an example has been described above in which the expanding material is uniformly contained in the holding member 31, the present invention is not limited to this, and the expanding material may be partially contained. 8 and 9 show a preferred example thereof. Next, these will be described in order. First, a first example will be described with reference to FIG. The expanding material may be contained only in the region R1 near the spinning processing portion S in the holding material. FIG. 8A is a plan view of the holding member 131 in this case. When this is wound around the carrier 11, the projection A in the figure fits into the recess B at the opposite end. FIG. 8B is a cross-sectional view showing a state in which the holding material 131 is wound around the carrier 11 and installed inside the container material 41 ′.

As described above, if the expanding material is contained only in the vicinity of the spinning portion S, it is possible to obtain a practically sufficient surface pressure compensation effect without containing the expanding material in the entire holding material. Can be reduced. As described above, when spinning the both ends of the container material 41 ′, the expanding material is contained on both sides of the holding material, and the expanding material is included in the vicinity of each spinning processing part. Is preferred.

Next, a second example will be described with reference to FIG. The expanding material may be contained only on the side R2 of the holding material that faces the container material 41 ′. FIG. 9 (a)
It is a top view of the holding material 231 in this case, and is provided with the projection A and the recessed part B similar to the above. FIG. 9 (b)
Is to wind the holding material 231 around the carrier 11 and
It is a front view (the figure seen along the axial direction) of the state installed in 1 '.

As described above, even if the expansion material is contained only on the side R2 facing the container material 41 ', the heat generated by the spinning process is transferred to the holding material 231 via the container material 41' having a high heat transfer coefficient. Since it is transmitted almost uniformly over the entire surface R2, a practically sufficient surface pressure compensation effect can be obtained. In this case, the effect can be easily obtained by simply impregnating the holding material that does not include the expanding material with the expanding material on its side or applying the expanding material to the surface on that side. .

Furthermore, if an inflating material is also contained on the side facing the carrier 11, in addition to the surface pressure compensation effect during spinning, a surface pressure compensation effect during the initial operation can be obtained. In order to obtain the effect at the time of the initial operation, it is preferable that the expanding material is contained so as to face the exhaust gas inlet side of the surface of the carrier 11. Although there are various other forms of the expansion material contained therein, it is preferable that the expansion material be contained continuously and equally along the longitudinal direction of the holder (that is, around the carrier). The position and width to be contained may be appropriately set. So, in short,
It may be contained only in the vicinity of the spinning section S on the side facing the container material 41 '.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a configuration of an exhaust gas purifying apparatus for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing the configuration of an exhaust system including the exhaust gas purifying apparatus;

FIG. 3 is a perspective view of a carrier of the exhaust gas purifying apparatus.

FIG. 4 is a view showing an arrangement state of a carrier unit inside a container material.

FIG. 5 is a view schematically showing a configuration of a spinning apparatus.

FIG. 6 is a diagram showing transmission of heat generated by spinning to a carrier holding material.

FIG. 7 is a view showing a surface pressure compensation effect according to the present invention.

FIG. 8 is a plan view and a sectional view showing another example of the carrier holding material according to the present invention.

FIG. 9 is a plan view and a front view showing another example of the carrier holding material according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Exhaust gas purification apparatus 11 ... Carrier 31 ... Holding material 41 ... Container 51 ... Chuck machine 61 ... Roll machine

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Ken Ouchi 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. F-term (reference) 3G090 AA03 3G091 AA17 AA18 AB02 AB03 AB13 GA12 GB10Z GB17X GB17Z GB19Z HA26 4D048 AB05 BA03X BA03Y BA41X BA41Y BB02 BB08 CA02 CA06 CC05 EA08 4G069 AA08 AA11 BA01A03 BB03 EA03 BB04 EA03

Claims (16)

[Claims] An exhaust gas purifying carrier for an internal combustion engine, wherein a carrier for purifying an exhaust gas is positioned inside a carrier container with a holding material containing an organic substance disposed on an outer periphery thereof and at least a part of the carrier container is reduced in diameter. A method of manufacturing a purifying apparatus, wherein the diameter reducing process is performed by attaching at least a part of the holding material to an expanding material that expands by heat generated during the diameter reducing process. A method for manufacturing an exhaust gas purification device. 2. A non-expandable holding material containing an organic substance which is burned off by thermal decomposition is wound around the outer surface of an exhaust gas purifying carrier and stored in a carrier container, and at least a part of the carrier container is reduced in diameter. A method for manufacturing an exhaust gas purifying apparatus for an internal combustion engine, wherein the holding material includes an expanding material that temporarily expands due to heat during the diameter reduction processing. Device manufacturing method. 3. The method for manufacturing an exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein said holding material is a mat mainly composed of non-expandable alumina fibers. 4. The method of manufacturing an exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein said expanding material is vermiculite or graphite. 5. The method according to claim 1, wherein the expanding material is unevenly distributed near a portion where the diameter reducing process is performed.
A method for manufacturing an exhaust gas purifying apparatus for an internal combustion engine according to any one of the first to third aspects. 6. The exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein the expansion member is provided on a side of the holding member facing the carrier container. Method. 7. The holding material according to claim 1, wherein an expanding material is also provided on a side of the holding material facing the carrier.
7. A method for manufacturing an exhaust gas purifying apparatus for an internal combustion engine according to any one of the above. 8. A non-expandable holding material containing an organic substance which is burned off by thermal decomposition is wound around the outer surface of the exhaust gas purifying carrier and stored in the carrier container, and at least a part of the carrier container is reduced in diameter. An exhaust gas purifying apparatus for an internal combustion engine, comprising: an expanding material that temporarily expands the holding member by heat generated during the diameter reduction processing. 9. The exhaust gas purifying apparatus for an internal combustion engine according to claim 8, wherein said holding member is a mat mainly composed of non-expandable alumina fibers. 10. An exhaust gas purifying apparatus for an internal combustion engine according to claim 8, wherein said expanding material is vermiculite or graphite. 11. The exhaust gas purifying apparatus for an internal combustion engine according to claim 8, wherein the expanding member is unevenly distributed near a portion where the diameter reducing process is performed. 12. An exhaust gas purifying apparatus for an internal combustion engine according to claim 8, wherein said expanding material is unevenly distributed on a side facing said carrier container. 13. A non-expandable holding material wound around a carrier for purifying exhaust gas and holding the carrier in a carrier container, comprising an organic substance which is burned down by thermal decomposition, and together with the carrier. A holding material for an exhaust gas purifying carrier, comprising: an expanding material that temporarily expands due to heat when the diameter of the carrier container is reduced while being stored in the container. 14. The holding material for an exhaust gas purifying carrier according to claim 13, wherein the expanding material is included so as to be unevenly distributed in a portion near the portion where the diameter reducing process is performed. 15. The apparatus according to claim 13, wherein said expanding material is included on a side forming a contact surface with said carrier container.
A holding material for the exhaust gas purifying carrier according to the above. 16. The holding material for an exhaust gas purifying carrier according to claim 115, further comprising an inflating material on the side forming the contact surface with said carrier.