JP2009142798A - Metallic catalyst carrier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metallic catalyst carrier which can be prevented from being broken due to thermal stress without increasing the manufacturing cost. <P>SOLUTION: The metallic catalyst carrier is provided with: a core (20) formed by winding a flat plate (21) and a corrugated plate (22) several times; and a cylindrical shell (30) for incorporating the core (20). The outer periphery of the shell (30) has a shape corrugated in the peripheral direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a catalyst carrier for purifying exhaust gas of an internal combustion engine used in automobiles and the like, and more particularly to a metal catalyst carrier capable of preventing damage due to thermal stress.

  Generally, a catalytic converter for purifying exhaust gas is disposed in an exhaust system of an engine such as an automobile. In this catalytic converter, a metal catalyst carrier comprising a core formed of a metal flat plate and corrugated plate and a shell in which the core is built is widely used.

  By the way, the exhaust gas passing through the core has a larger flow velocity in the central portion than in the outer peripheral portion of the core. Therefore, in the metal catalyst carrier, a temperature distribution is generated such that the temperature at the center is higher and the temperature at the outer periphery is lower due to contact with the high-temperature exhaust gas, heat generation by the catalytic reaction, and heat release from the outer cylinder to the outside air. Due to this temperature distribution, there is a difference in the amount of expansion and contraction between the core and the outer cylinder, but the plate thickness of the core and corrugated sheet that make up the core is generally much thinner than the thickness of the outer cylinder. Thermal stress acts on the core. The flat plate and corrugated sheet of the core are plastically deformed by repeated expansion and contraction, resulting in metal fatigue, and finally the core flat plate and corrugated sheet may be broken.

In response to such a problem, a metal carrier for a catalytic converter is disclosed in which the shell is doubled to reduce the stress generated by the difference in thermal expansion between the inner cylinder and the outside, thereby improving the durability of the catalytic converter (Patent Document). 1).
JP 09-108575 A

  The catalyst carrier of Patent Document 1 described above prevents damage to the core due to thermal stress. However, since the shell is doubled and the inner and outer cylinders are made of different materials, there is a problem in cost. there were. In addition, since the shell is doubled, there is a problem that the cross-sectional area of the core in the catalyst carrier is reduced and the capacity of the catalyst is reduced.

  The present invention has been made paying attention to such problems, and an object thereof is to provide a metal catalyst carrier capable of preventing damage due to thermal stress without increasing cost.

  The invention of claim 1 is provided with a core configured by multiply winding a flat plate and a corrugated plate, and a cylindrical shell that houses the core, and the outer periphery of the shell is circumferential. It has a waveform shape.

  According to a second aspect of the present invention, in the first aspect of the present invention, the inner periphery of the shell has a corrugated shape in the circumferential direction, and the outer periphery of the core is formed on the inner peripheral surface of the shell. It is characterized by contacting with a raised portion of the shape.

  According to a third aspect of the present invention, in the invention of the second aspect, the corrugated plate is disposed on the outermost circumferential side of the core, and the interval between the corrugated shapes on the inner circumferential surface of the shell is the outermost circumferential surface of the core. It is an integral multiple of the interval of the corrugated shape of the corrugated plate on the side.

  According to the first aspect of the present invention, since the outer periphery of the shell has a corrugated shape in the circumferential direction, the efficiency of releasing the heat of the shell to the outside air or the like is increased, and thereby, the shell is embedded in the shell having a relatively small heat capacity. Since the temperature difference with the core is reduced, the generation of thermal stress can be reduced, so that damage to the core can be prevented.

  According to the invention of claim 2, the inner periphery of the shell has a corrugated shape in the circumferential direction, and the outer periphery of the core is in contact with the inner peripheral surface of the shell at the raised portion of the corrugated shape. The area of the contact portion with the core can be reduced, and the thermal conductivity between the shell and the core is reduced. As a result, the temperature difference between the outer peripheral portion of the core that is in contact with the shell having a relatively large heat capacity and the central portion of the core is reduced, so that the occurrence of thermal stress can be reduced, so that damage to the core can be prevented.

  According to invention of Claim 3, the said corrugated sheet is arrange | positioned at the outermost periphery side of the core, and the space | interval of the waveform shape of the inner peripheral surface of a shell is the space | interval of the waveform shape of the corrugated sheet of the outermost periphery side of the said core. Since it is an integer multiple, the shell and the core are securely fixed. Thereby, the workability | operativity at the time of an assembly | attachment improves, and the manufacturing cost of a metal catalyst carrier falls.

  Hereinafter, a metal catalyst carrier according to an embodiment of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a perspective view showing a metal catalyst carrier 10 according to a first embodiment of the present invention.

  The metal catalyst carrier 10 includes a core 20 and a cylindrical shell 30. The core 20 is configured by winding a flat plate 21 made of a plate-like foil material and a corrugated plate 22 which is a member obtained by processing the plate-like foil material into a corrugated shape. As will be described later, the outer peripheral side and the inner peripheral side of the shell 30 have a waveform shape in the circumferential direction.

  The metal catalyst carrier 10 is provided in an exhaust pipe of an engine or the like, and carries a catalyst material made of noble metal particles or the like on the surface of the core 20 to reduce unburned components or nitrogen oxides in the exhaust gas. Functions as a converter.

  Here, the exhaust gas passing through the core 20 has a larger flow velocity toward the center than the outer periphery of the core 20. On the other hand, the shell 30 in which the core is built has a large heat capacity because the plate thickness is larger than that of the core 20. Moreover, since the outer periphery is in contact with the outside air, it is easy to release heat. For this reason, a temperature difference arises in the center part of the core 20, and the outer peripheral part of the core 20 which is in contact with the shell 30.

  Further, the exhaust gas temperature varies greatly depending on the operating condition of the engine. For example, the exhaust gas temperature becomes high near the ideal air-fuel ratio or at a high load. On the other hand, when the fuel is cut, the air taken into the engine is discharged as it is into the exhaust pipe, so the exhaust gas temperature becomes low.

  With such a structure, for example, when the exhaust gas temperature suddenly rises, the temperature of the central portion of the core 20 suddenly rises with the exhaust gas temperature, but the outer peripheral portion of the core 20 in contact with the shell 30 is The heat capacity of the shell 30 does not increase as much as the central portion. Similarly, when the exhaust gas temperature rapidly decreases, the temperature on the central portion side of the core 20 rapidly decreases with the exhaust gas temperature, but the outer peripheral portion of the core 20 in contact with the shell 30 Due to the heat capacity of the center, it does not descend as much as the center.

  Conventionally, a large temperature difference occurs between the central portion and the outer peripheral portion of the core 20 due to such fluctuations in the exhaust gas temperature, and stress due to thermal expansion / contraction due to fluctuations in the exhaust gas temperature acts to cause damage to the core 20. It was.

  Therefore, in the first embodiment of the present invention, as described in detail below, the shell 30 is structured to have a corrugated shape in the circumferential direction, whereby the temperatures of the center portion and the outer peripheral portion of the core 20 are increased. A metal catalyst carrier 10 for reducing the difference was configured.

  FIG. 2 is a perspective view showing the shell 30 of the first embodiment of the present application.

  As shown in FIG. 2, the shell 30 is a cylindrical tubular member having an outer peripheral side and an inner peripheral side having a corrugated shape in the circumferential direction.

  As shown in FIG. 1, the metal catalyst carrier 10 is configured by including a cylindrical core 20 in a shell 30 having a corrugated shape in the circumferential direction. Since the outermost peripheral portion of the core 20 is a flat plate 21, the corrugated protruding portion (convex portion) on the inner peripheral surface of the shell 30 is in contact with the flat plate 21 at the outermost peripheral portion of the core 20. The shell 30 and the core 20 are joined by brazing or the like.

  The shell 30 is constituted by a plate material 31 which is a plate-like member having a corrugated shape as shown in FIG. More specifically, the cylindrical shell 30 is configured by bending the corrugated plate material 31 into a cylindrical shape and joining both ends in the long side direction to each other by brazing or the like.

  In addition, this board | plate material 31 is made into the shape as shown below more preferably (refer FIG. 4).

Waveform pitch p = 2t to 5t
Waveform tip radius r = 0.5t-2t
Wave height h = 0.2t to 2t
(Note that the thickness of the plate is t)
The length of the plate 31 in the long side direction is an integral multiple of the pitch p. The corrugated shape is parallel to the exhaust gas flow direction, that is, parallel to the short side direction of the plate.

  By configuring the shell 30 from the plate material 31 processed in this way, the surface area on the outer peripheral side of the shell 30 can be increased. Further, the radial rigidity can be slightly reduced without significantly reducing the strength of the shell 30.

  Note that the number of members of the shell 30 is increased by about 10% as compared with a shell having a substantially circular outer shape. However, the cost can be reduced as compared with the case of duplexing with different materials as in the above cited reference 1.

  Moreover, the shell 30 does not necessarily need to be configured by processing the plate material 31 into a cylindrical shape. For example, the shell 30 may be configured by processing a corrugated shape of a cylindrical member whose outer shape is a substantially perfect circle by hydroforming or the like.

  Further, in the metal catalyst carrier 10 of the present embodiment, a gap exists between the corrugated shape of the shell 30 and the flat plate 21 at the outermost peripheral portion of the core 20. This is configured such that when the metal catalyst carrier 10 is incorporated into the exhaust pipe, the exhaust gas does not pass through the gap, for example, by welding.

  As described above, in the metal catalyst carrier 10 of the first embodiment of the present invention, the shell 30 has a cylindrical shape having a corrugated shape in the circumferential direction. Thereby, since the surface area of the outer peripheral side of the shell 30 increases compared with a perfect circle, an ellipse, or an ellipse shape, the heat dissipation of the shell 30 increases. Thereby, the temperature difference of the outer peripheral part of the core 20 which contact | connects the shell 30 with comparatively large heat capacity, and the core center part with small heat capacity can be made small.

  Further, since the inner peripheral side of the shell 30 has a corrugated shape, the area of the contact portion with the core 20 is reduced. That is, only the protruding portion (protruding portion) on the inner peripheral side of the corrugated shape of the shell 30 is in contact with the flat plate 21 at the outermost peripheral portion of the core 20. Therefore, since heat transfer between the shell 30 and the core 20 is reduced, the temperature difference between the central portion and the outer peripheral portion of the core 20 that is in contact with the shell 30 can be reduced.

  As a result, the temperature difference between the central portion and the outer peripheral portion of the core 20 that is in contact with the shell 30 is reduced, so that the thermal stress generated by the thermal expansion difference is reduced, and the metal catalyst carrier 10 that does not easily break the core 20 is configured. can do.

  Further, since the shell 30 has a corrugated shape, the radial rigidity is reduced as compared with a perfect circle, ellipse, or oblong shape. Therefore, the radial stress in the core 20 due to thermal expansion / contraction can be absorbed.

  Further, since the inner peripheral side of the shell 30 has a corrugated shape, the area of the contact portion with the core 20 is reduced, so that the amount of brazing material for joining the shell 30 and the core 20 can be reduced. Thereby, the manufacturing cost of the metal catalyst carrier 10 can be reduced.

  Further, since the corrugated shape of the shell 30 is about 0.5 to 2 times the plate thickness as described above, the cross-sectional area occupied by the shell 30 in the cross-sectional area of the metal catalyst carrier 10 is a perfect circle, an ellipse or Compared to the oval shape, the increase is slight. Therefore, the cross-sectional area of the core 20 in the metal catalyst carrier 10 is not reduced, and the capacity of the catalyst is not reduced.

<Second Embodiment>
Next, the metal catalyst carrier 10 of the second embodiment will be described.

  In the first embodiment described above, the metal catalyst carrier 10 is configured by the shell 30 having a circumferential corrugated shape and the core 20 whose outermost peripheral portion is the flat plate 21.

  On the other hand, in the second embodiment, the metal catalyst carrier 10 is constituted by a shell 30 having a corrugated shape in the circumferential direction and a core 20 which is a corrugated plate 22 having an outermost peripheral portion having a corrugated shape. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and the description is abbreviate | omitted.

  FIG. 5 is an explanatory diagram of a main part of the metal catalyst carrier 10 according to the second embodiment of the present invention.

  The shell 30 has the same shape as that of the first embodiment described above. That is, the cylindrical plate member 31 having a circumferential corrugated shape is bent into a cylindrical shape, and both ends in the long side direction are joined to each other by brazing, whereby the substantially cylindrical shell 30 having the circumferential corrugated shape is obtained. Composed.

  On the other hand, the outermost peripheral part of the core 20 has a waveform shape. That is, the flat plate 21 and the corrugated plate 22 are wound in multiple layers so that the outermost peripheral portion of the core 20 becomes the corrugated plate 22.

  The pitch on the inner peripheral side of the corrugated shape of the shell 30 (interval of the corrugated ridges) is an integral multiple of the pitch of the corrugated plate 22 on the outermost peripheral part of the core 20 (interval of the corrugated ridges). As described above, the shell 30 and the core 20 are more preferably configured to have the same pitch.

  In general, in the process of assembling the core 20 to the shell 30, first, the flat plate 21 and the corrugated plate 22 of the core 20 are wound and inserted into the shell 30. Then, the winding is released and the core 20 is brought into close contact with the shell 30 by the elasticity of the flat plate 21 and the corrugated plate 22. Thereafter, the shell 30 and the core 20 are brazed.

  In this step, as shown in FIG. 5, the raised portion (convex portion) of the corrugated plate 22 of the core 20 is engaged with the depressed portion (recessed portion) of the corrugated shape on the inner peripheral side of the shell 30, thereby 20 will be reliably fixed to the circumferential direction of the shell 30, and workability | operativity at the time of an assembly | attachment will improve.

  As described above, the metal catalyst carrier 10 of the second embodiment of the present invention has the same effects as those of the first embodiment described above, by the same configuration as that of the first embodiment.

  Further, the raised portion of the corrugated plate 22 of the core 20 is engaged with the depressed portion of the corrugated shape on the inner peripheral side of the shell 30. As a result, the shell 30 and the core 20 are securely fixed, so that workability at the time of assembly is improved and the manufacturing cost of the metal catalyst carrier 10 is reduced.

  The metal catalyst carrier 10 of the present invention is not limited to an automobile, and can be used for purifying exhaust gas from various internal combustion engines.

1 is a perspective view of a metal catalyst carrier according to a first embodiment of the present invention. It is a perspective view of the shell of the 1st Embodiment of this invention. It is a perspective view of the board | plate material which comprises the shell of the 1st Embodiment of this invention. It is explanatory drawing of the board | plate material which comprises the shell of the 1st Embodiment of this invention. It is explanatory drawing of the metal catalyst carrier of the 2nd Embodiment of this invention.

Explanation of symbols

10 Metal catalyst carrier 20 Core 21 Flat plate 22 Corrugated plate 30 Shell 31 Plate material

Claims (3)

A core (20) configured by multiply winding a flat plate (21) and a corrugated plate (22), and a cylindrical shell (30) that houses the core (20),
The metal catalyst carrier according to claim 1, wherein the outer periphery of the shell (30) has a corrugated shape in a circumferential direction. The metal catalyst support according to claim 1, wherein
The inner periphery of the shell (30) has a circumferential waveform.
The metal catalyst carrier according to claim 1, wherein an outer periphery of the core (20) is in contact with an inner peripheral surface of the shell (30) by the corrugated raised portion. The metal catalyst support according to claim 2,
The core (20) has the corrugated plate (22) disposed on the outermost peripheral side thereof,
The metal catalyst carrier characterized in that the interval of the corrugated shape of the inner peripheral surface of the shell (30) is an integral multiple of the interval of the corrugated shape of the corrugated plate (22) on the outermost peripheral side of the core (30).

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