JPH0610132Y2 - Exhaust gas purification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention supports an exhaust gas purifying catalyst, which is generally provided 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 including a metallic honeycomb core body and a tubular metal case. More specifically, the present invention relates to an exhaust gas purifying apparatus of this type used under severe conditions, and in particular, an exhaust gas that can effectively prevent separation between constituent members and cracking or damage of the members due to thermal stress. The present invention relates to a gas purification device.

(Prior Art) Conventionally, an exhaust gas purifying apparatus of this type has a contact portion between a flat strip made of a heat-resistant thin steel plate and a corrugated strip made by corrugating the thin steel plate. As described above, the honeycomb-shaped laminated body (hereinafter, referred to as a honeycomb core body) having a large number of mesh-like vent holes for the exhaust gas passage, which is manufactured by stacking and stacking them in a spiral shape in a lump, is manufactured. And a cylindrical metal case with both ends open.

The honeycomb core body and the metal case are heated by heat transferred from the high-temperature exhaust gas itself and an exothermic reaction between the exhaust gas and the purification catalyst, and thermal stress and heat in a high-temperature atmosphere accompanying this heating. The honeycomb core body and the metal case are firmly fixed to each other by brazing or the like over the entire abutting surface so as to withstand deformation and vibration during traveling of the automobile. Therefore, the heat of the honeycomb core body is quickly transferred to the metal case to be dissipated, and as a result, the thermal stress becomes larger near the outer peripheral surface of the honeycomb core body. It goes without saying that the abutting portions of the flat plate-shaped band member and the corrugated plate-shaped band member that form the honeycomb core body are fixed by various methods.

(Problems to be Solved by the Invention) However, the conventional exhaust gas purifying apparatus composed of the honeycomb core body and the metal case described above cannot endure long-term use. In particular, in the axial direction of the honeycomb core body (that is, the exhaust gas flow direction), due to thermal stress and thermal deformation under the high temperature atmosphere described above, the outermost peripheral surface and the inner wall surface of the metal case are largely separated, and There is a drawback that the flat plate and / or the corrugated plate constituting the honeycomb core body is also peeled, cracked, and damaged greatly.

This is a correction to the idea that the honeycomb core body and the metal case may simply be firmly fixed to each other.
The present inventor has confirmed that the outermost peripheral surface of the honeycomb core body is separated from the inner wall surface of the metal case, the separation between the flat plate-like and corrugated strip material forming the honeycomb core body, cracking and damage of these strip materials. We have diligently studied measures to prevent it over a long period of time.

As a result, two honeycomb core bodies are arranged apart from each other in the metal case having the expanded diameter portion instead of a single honeycomb core body, and the honeycomb core bodies in the vicinity of the opening of the metal case are provided. When the outer peripheral surface is fixed to the inner wall surface of the metal case, the non-fixed portion in the vicinity of the separated portion can expand and contract in the axial direction, so that thermal stress and thermal deformation can be dispersed and relaxed very effectively. The space formed by separating the honeycomb core body and the space formed by the expanded diameter portion of the honeycomb core body and the metal case give the effect of causing turbulence in the flow of exhaust gas and improve the purification efficiency. In addition, the inventors have found that a heat insulating space for the outer peripheral surface of the honeycomb core body can be made more uniform and the uneven distribution of deformation due to thermal stress can be prevented, and the present invention has been completed.

[Constitution of device]

(Means for Solving Problems) The present invention can be summarized as follows. In the present invention, the flat strip material and the corrugated strip material of thin metal plates are stacked so as to abut each other, and they are collectively swirled. Cylindrical metal having both ends opened and two expanded diameters of two honeycomb core bodies having a large number of mesh-like air vent passages in the axial direction, which are manufactured by winding or laminating in a circular shape or layering. In an exhaust gas purifying apparatus which is fixedly separated in a case, an outer peripheral surface of each honeycomb core body near the opening of the metal case is fixed to an inner wall surface of the metal case, and a separated portion of each honeycomb core body is fixed. The present invention relates to an exhaust gas purifying device, wherein an outer peripheral surface in the vicinity is not in contact with an inner wall surface of a metal case.

Hereinafter, the configuration of the present invention will be described in detail.

As described above, in the conventional exhaust gas purifying apparatus, generally, one honeycomb core body is packed in a tubular metal case having open both ends, and the outer peripheral surface of the honeycomb core body and the inner wall surface of the metal case are firmly fixed to each other. Manufactured. However, the exhaust gas purifying device having such a structure cannot endure long-term use.

In particular, the exhaust gas purifying device is susceptible to thermal stress and thermal deformation (distortion), which is a major factor that reduces durability.

That is, it goes without saying that the exhaust gas purifying device undergoes large thermal stress and thermal deformation due to the heating / cooling cycle depending on the start / stop and load level. .

In this respect, when considering the situation during traveling, the exhaust gas purification device shows that the exhaust gas flow rate distribution is different (the flow rate at the central portion is higher than that at the peripheral portion), and the exhaust gas purification apparatus carried on the surface portion of the honeycomb core body. The central portion of the honeycomb core body is exposed to a higher temperature than the peripheral portion due to the contact reaction (exothermic reaction) between the exhaust catalyst (catalyst such as Pt, Pd, Rh) and the exhaust gas.

When the temperature gradient inside the above-mentioned honeycomb core body is examined in more detail, the temperature gradient between the outer peripheral surface of the honeycomb core body and a portion slightly inward thereof is significantly larger than the temperature gradient in the same distance in the vicinity of the central portion. . This is because the outer peripheral surface of the honeycomb core body is fixed to the tubular metal case that is in contact with the outside air, so that the heat transferred from the honeycomb core body through the fixed contact surface with the metal case to the outside. Since the heat is dissipated, it is further promoted.

Therefore, due to this, strain due to large thermal stress occurs, and even if the outermost peripheral surface of the honeycomb core body is fixed to the inner wall surface of the metal case by brazing, etc. And both try to peel off.
Similarly, the honeycomb core body is formed between the outer peripheral surface of the honeycomb core body which is fixed to the inner wall surface of the metal case by brazing or the like by the deforming force (strain) based on the above-mentioned thermal stress and the portion slightly inside thereof. This causes peeling of the abutting portion between the flat plate-shaped strip material and the corrugated plate-shaped strip material, cracking and damage of these strip materials.

In order to suppress or prevent the above-mentioned peeling and the like, it is necessary to take measures to alleviate the deforming force (strain) based on the thermal stress, especially in the vicinity of the outer peripheral surface of the honeycomb core body.

Therefore, in the present invention, two honeycomb core bodies are arranged with a desired width apart in a cylindrical metal case having both ends opened and having a diameter-expanded portion excluding a portion near the opening. A technical configuration is adopted in which the contact surfaces of the two in the vicinity of the opening are fixed by brazing or the like, and the non-fixed portion in the vicinity of the separated portion of the honeycomb core body can be expanded and contracted in the axial direction.

In the present invention, the honeycomb core body and the metal case are fixed to each other in the following manner because of the use of the metal case having the expanded diameter portion. That is, each honeycomb core body is fixed to the inner wall surface of the metal case having the expanded diameter portion by fixing the outer peripheral surface of each honeycomb core body near the opening of the metal case to the inner wall surface of the metal case near the opening. Stick to it. As a result, the outer peripheral surfaces of the other portions near the opening of the metal case of each honeycomb core body form a void portion having a heat insulating effect together with the inner wall surface of the expanded diameter portion of the metal case, and can be expanded and contracted in the axial direction. Become. In the present invention, the formation of the void having the heat insulating effect described above
The honeycomb core body part that is not fixed to the inner wall surface of the metal case resonates due to vibration when the vehicle is running,
It goes without saying that a spacer may be appropriately provided in the void portion in order to provide vibration resistance.

In the exhaust gas purifying apparatus having the above-described structure of the present invention, each honeycomb core body is arranged in a metal case having a diameter-increasing portion having a predetermined width and having a heat insulating and heat insulating effect, and the vicinity of the separating portion is in the axial direction. Since it is fixed only in the vicinity of the opening so as to be expandable and contractable, it is possible to effectively absorb the axial deformation due to a large thermal stress particularly in the vicinity of the outer peripheral surface of the honeycomb core body. Further, the separating portion formed between the honeycomb core bodies can provide an effect of causing turbulence in the flow of the exhaust gas, thereby making the purification capacity uniform. Further, the voids formed between the outer peripheral surface of each honeycomb core body and the expanded diameter portion of the metal case have adiabatic heat insulating effect and a mixture of exhaust gas (the high temperature gas in the central portion wraps around to the low temperature side in the peripheral void portions). It is possible to eliminate the local uneven distribution of thermal stress and thermal deformation, that is, to improve the durability of the exhaust gas purifying device. .

Embodiments of the present invention will be described below with reference to the drawings, but it goes without saying that the present invention is not limited to the illustrated ones.

1 and 2 show an embodiment of an exhaust gas purifying apparatus according to the present invention. FIG. 1 is a partially cutaway perspective view of the exhaust gas purifying apparatus, and FIG. FIG.

As shown in the drawing, an exhaust gas purifying device according to the present invention (1)
The two honeycomb core bodies (2, 2) are arranged in a metal case (3) having open ends at both ends and having a diameter-enlarged portion (31) with a predetermined width apart from each other. It is manufactured by fixing the core body (2, 2) and the metal case (3). In the fixing, the fixing of the respective honeycomb core bodies (2, 2) and the metal case (3) is performed by fixing the respective honeycomb core bodies as shown in FIG.
The outer peripheral surface in the vicinity of the opening of the metal case (3) of (2, 2) may be fixed by brazing, whereby a space between the honeycomb core bodies (2, 2) in the metal case, a honeycomb core A space having a heat insulating and heat retaining effect is formed between the body (2, 2) and the expanded diameter portion (31) of the metal case (3). Further, with the above-mentioned structure and as is clear from FIG. 1, the honeycomb core body is
Since the outer peripheral surface of the (2, 2) near the separated portion is not fixed to the inner wall surface of the metal case (3), it can be expanded and contracted in the axial direction.

The honeycomb core body (2) has a flat strip material (21) made of a heat-resistant thin steel plate and a corrugated strip material (22) obtained by corrugating the flat strip material (21) in contact with each other. It is manufactured by stacking so as to have a part and then winding and laminating both in a spiral shape. By this winding and stacking, a large number of mesh-like ventilation hole passages (23) which become exhaust gas passages are automatically formed.

As the flat strip (21), for example, a heat-resistant steel of Cr 20%, Al 5% with a thickness of 0.05 mm and a width of 30 mm, and a corrugated strip (2
As 2), the corrugated plate material 21 is used. In this example, two honeycomb core bodies having a short axial length, which were manufactured by winding and laminating these members, were used to form a honeycomb core body (2, 2).

FIG. 3 is a partial vertical sectional view of an exhaust gas purifying apparatus according to a second embodiment of the present invention. The difference from the first embodiment is that a spacer is provided in the void portion in order to improve the vibration resistance of the exhaust gas purifying apparatus. The spacer is fixed to the outer peripheral surface of each honeycomb core body (2, 2) in the vicinity of the separated portion, and is brought into contact with the inner wall surface of the expanded diameter portion (31) of the metal case (3), Honeycomb core body (2,2)
It does not prevent the vicinity of the separated portion from expanding and contracting in the axial direction to absorb strain in the axial direction due to thermal stress. The spacer is
It may be fixed to the inner wall surface of the expanded diameter portion (31) of the metal case (3) and brought into contact with the outer peripheral surface of the honeycomb core body (2, 2) in the vicinity of the separated portion. Further, the spacers may be provided on the outer peripheral surface of the honeycomb core body (2, 2) in the vicinity of the separated portions at predetermined intervals in the circumferential direction, or may be provided over the entire circumference. If the exhaust gas flow holes are provided in the spacer so that the high-temperature gas in the distant portion can also flow into the gap when it is provided over the entire circumference, a more uniform temperature distribution in the metal case can be obtained. Therefore, uneven distribution of strain of thermal stress can be prevented.

FIG. 4 is a partial vertical sectional view of an exhaust gas purifying apparatus according to a third embodiment of the present invention. This is different only in the shape of the expanded diameter portion of the metal case from that of the above-described embodiment.

FIG. 5 is a front view of an exhaust gas purifying apparatus according to a fourth embodiment of the present invention. As compared with the first embodiment, this is a honeycomb core body manufactured by stacking flat plate-shaped strips and corrugated strip-shaped strips in layers, and a metal case having a racetrack cross section. The difference is that the one used is.

[Effect of device]

In the exhaust gas purifying apparatus of the present invention, two honeycomb core bodies are arranged in a metal case having an opening and a diameter-expanding portion, with a predetermined width therebetween, and each honeycomb core body and the metal It is manufactured by fixing to the case at a portion near the opening of the metal case. As a result, in the exhaust gas purifying apparatus of the present invention, a space between the honeycomb core bodies is formed inside the metal case, and a space having a heat insulation effect is formed between the outer peripheral surface of the honeycomb core body and the expanded diameter portion of the metal case. Further, the vicinity of the separated portion of the honeycomb core body can be expanded and contracted in the axial direction. Further, the above-described fixing means and the formation of the space portion have the following excellent effects in the exhaust gas purifying apparatus of the present invention.

(i) The separated portion provided between the two honeycomb core bodies is deformed (strained) due to thermal stress in the axial direction of the honeycomb core body in order to allow expansion and contraction of the honeycomb core body in the vicinity of the separated portion in the axial direction. ) Can be effectively absorbed. Therefore, in addition to the separation between the honeycomb core body and the metal case, especially the flat plate forming the honeycomb core body near the outer peripheral surface of the honeycomb core body (between the outer peripheral surface and a portion slightly inward of the outer peripheral surface) which receives the thermal stress strain in a concentrated manner. It is possible to effectively prevent peeling between the strip material and the corrugated strip material, and cracking and damage of these members.

(ii) By providing the separating portion between the honeycomb core bodies, it is possible to impart an effect of causing turbulence in the flow of exhaust gas, and thus it is possible to more uniformly purify exhaust gas.

(iii) By providing a void between the outer peripheral portion of the honeycomb core body and the expanded diameter portion of the metal case, the void portion performs a heat insulating and heat retaining function, which makes the temperature distribution of the honeycomb core body uniform. It In addition, since the high temperature exhaust gas flow can be made to flow into the voids in cooperation with the above-mentioned separating portion, the temperature distribution inside the honeycomb core body is made more uniform.
This is an important point in improving the deterioration of durability due to uneven distribution of thermal stress in the exhaust gas purification device.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of an exhaust gas purifying apparatus according to a first embodiment of the present invention, and FIG. 2 is a partial longitudinal sectional view of an exhaust gas purifying apparatus according to the first embodiment. FIG. 3 is a partial vertical cross-sectional view of the exhaust gas purification apparatus of the second embodiment, and FIG. 4 is a partial vertical cross-sectional view of the exhaust gas purification apparatus of the third embodiment. FIG. 5 is a front view of the exhaust gas purifying apparatus of the fourth embodiment. DESCRIPTION OF SYMBOLS 1 ... Exhaust gas purification device 2 ... Honeycomb core 21 ... Flat strip 22 ... Corrugated strip 23 ... Mesh ventilation passage 3 ... Metal case 31 ... Expanded part of metal case

Claims (6)

[Scope of utility model registration request] 1. A honeycomb core body having a plurality of mesh-like ventilation holes formed in the axial direction, which are manufactured by stacking flat plate-shaped strips and corrugated strips of thin metal plates so as to abut each other. In an exhaust gas purifying apparatus for carrying an exhaust gas purifying catalyst, which is fixedly spaced and fixed in a cylindrical metal case having both ends opened and having an enlarged diameter portion, wherein the metal of each honeycomb core body is An exhaust gas characterized in that the outer peripheral surface near the opening of the case is fixed to the inner wall surface of the metal case, and the outer peripheral surface near each of the separated portions of the respective honeycomb core bodies does not contact the inner wall surface of the metal case. Gas purification device. 2. A honeycomb core body is manufactured by stacking flat plate-shaped strips and corrugated strip-shaped strips so that they come into contact with each other, and winding and stacking them in a spiral shape. Exhaust gas purifier according to. 3. The exhaust gas purifying apparatus according to claim 1, wherein the honeycomb core body is manufactured by laminating flat plate-shaped strips and corrugated plate-shaped strips in a layered structure. 4. The spacer according to claim 1, further comprising a spacer fixed to the outer peripheral surface of the honeycomb core body in the vicinity of the separated portion, the spacer being in contact with the inner wall surface of the expanded diameter portion of the metal case. Exhaust gas purification device. 5. The exhaust gas purifying apparatus according to claim 4, wherein the spacers are provided at predetermined intervals in the circumferential direction. 6. The exhaust gas purifying apparatus according to claim 4, wherein the spacer is provided over the entire circumference in the circumferential direction.