JP2005152772A - Catalyst carrier made of metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst carrier made of a metal capable of accelerating its catalytic function and improving the durability by lessening the effect of thermal stress in the end part on the upstream side. <P>SOLUTION: The catalyst carrier made of a metal comprises a honeycomb structure body 1 to be installed in an outer cylinder 2 made of a metal, the honeycomb structure body 1 being formed by alternately laminating and winding roughly corrugated sheets 4 and finely corrugated or flat sheets 5 of metal thin sheets, and a plurality of exhaust gas flow holes 4a, 5a are formed in at least in the roughly corrugated sheets 4 or the finely corrugated or flat sheets 5 for enabling exhaust gas to flow in the radius direction of the honeycomb structure body 1 itself. The exhaust gas flow holes 4a, 5a are formed in portions other than the end part 7 on the upstream side of the honeycomb structure body 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a metal catalyst carrier used as a catalytic converter for exhaust gas purification.

Conventionally, a metal catalyst carrier used as a catalytic converter is formed by winding a honeycomb structure housed in a metal outer cylinder in multiple layers by alternately stacking large corrugated metal plates and corrugated plates or flat plates. In addition, a plurality of exhaust gas flow holes that allow the exhaust gas to flow in the radial direction of the honeycomb structure are formed in at least one of the large wave plate, the small wave plate, and the flat plate. There is a structure in which the flow resistance of exhaust gas passing therethrough is increased to promote the catalytic action (see, for example, Patent Document 1).
JP 2002-143893 A

However, since the metal catalyst carrier has a lower heat capacity than the ceramic catalyst carrier, it is easy to be warmed by the heat of the exhaust gas and the catalyst is activated quickly, so that it is relatively close to the engine in the middle of the exhaust pipe. Of course, the metal catalyst carrier interposed therein has a severe thermal environment, and in particular, the upstream end of the metal catalyst carrier has a high-temperature and high-speed exhaust gas flowing from the engine. However, there is a problem that it is easily affected by thermal stress accompanying thermal expansion / contraction.
Note that it is not preferable to increase the rigidity of the metal corrugated large and small corrugated plates or flat plates because the exhaust flow cross-sectional area required for the desired catalytic effect cannot be secured.

  The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to reduce the influence of the upstream end due to thermal stress while promoting the catalytic action of the metal catalyst carrier. An object of the present invention is to provide a metal catalyst carrier capable of improving durability.

  In order to solve the above-mentioned problems, in the metal catalyst carrier according to claim 1, the honeycomb structure housed in the metal outer cylinder is multiplexed by alternately stacking the large wave plate and the small wave plate or the flat plate of the metal thin plate. In a metal catalyst carrier that is formed by winding, and has a plurality of exhaust gas flow holes formed in at least one of the large wave plate, the small wave plate, and the flat plate to allow exhaust gas to flow in the radial direction of the honeycomb structure The exhaust gas circulation holes are formed in a range excluding the upstream end of the honeycomb structure.

  The metal catalyst carrier according to claim 2, wherein in the metal catalyst carrier according to claim 1, the exhaust gas flow holes are formed in a range excluding a range of 10 mm from the upstream end face of the honeycomb structure to the rear. And

  According to a third aspect of the present invention, in the metal catalyst carrier according to the first or second aspect, the honeycomb structure is press-fitted into an outer cylinder, and a raw foil material is provided at the downstream end of the honeycomb structure. The honeycomb structure and the outer cylinder are fixed by rolling and heat-treating.

  In the metal catalyst carrier according to claim 1, the high-speed and high-temperature exhaust gas flowing in from the engine side is directly received, and the upstream end of the honeycomb structure becomes particularly hot, and the thermal expansion and contraction thereof. The accompanying thermal stress is also greater than other parts, but since no exhaust gas circulation hole is formed at the upstream end, the rigidity is insufficient as in the conventional invention, and it is affected by the thermal stress. There is no risk of facilitation, and the durability of the metal catalyst carrier can be improved.

  In addition, since there is no increase in exhaust resistance at the upstream end of the honeycomb structure, the exhaust gas can flow smoothly in a rectified state, and the exhaust resistance of the exhaust gas after passing through the upstream end Is increased by a plurality of exhaust gas circulation holes, so that the catalyst can be discharged backward while promoting the catalytic action.

  In the metal catalyst carrier according to claim 2, since the exhaust gas flow hole is formed in a range excluding the range of 10 mm from the upstream end surface of the honeycomb structure to the rear, it acts on the upstream end portion of the current metal catalyst carrier. Therefore, the present invention is suitable for application to a metal catalyst carrier interposed immediately after an exhaust manifold having the most severe thermal environment.

  In the invention of claim 3, the honeycomb structure is press-fitted into an outer cylinder, and a raw foil material is wound on the downstream end of the honeycomb structure and heat-treated, Since the outer cylinder is fixed, the outer cylinder and the honeycomb structure are fixed to each other at the downstream end, thereby preventing the thermal stress accompanying the thermal expansion / contraction of the outer cylinder from adversely affecting the upstream end.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a side sectional view showing a metal catalyst carrier of an embodiment of the present invention, FIG. 2 is a perspective view showing a honeycomb structure of the present embodiment, and FIG. 3 is in the middle of winding a large wave plate and a flat plate FIG. 4 is a diagram showing a reaction distribution of the catalyst of the metal catalyst carrier, and FIG. 5 is an overall view of an exhaust pipe to which the metal catalyst carrier of the present invention is applied.

  As shown in FIGS. 1 and 2, the metal catalyst carrier A of Example 1 mainly includes a honeycomb structure 1, an outer cylinder 2, and a raw foil material 3.

  The honeycomb structure 1 is formed in a honeycomb shape in which a large corrugated plate 4 and a flat plate 5 of metal thin plates of several tens of microns are alternately stacked, and the flat plate 5 is wound outwardly. A catalyst carrier layer made of alumina or the like is formed on the surface of the cell passage), and a catalyst metal is supported on the catalyst carrier layer to form an exhaust gas purification catalyst. When passing through the honeycomb structure, It works to purify HC, CO, NOx, etc.

  As shown in FIG. 3, before the corrugated plate 4 is processed into a corrugated shape, the upstream end 6 of the honeycomb structure 1, more specifically, a range of 10 mm from the tip that becomes the upstream end 7 of the honeycomb structure 1 is used. Except for the part (shown by h in the figure), a plurality of long hole-shaped exhaust gas circulation holes 4a are formed in advance at predetermined intervals. On the other hand, the honeycomb structure 1 is formed on the flat plate 5 similarly to the corrugated plate. A plurality of exhaust gas flow holes 5a are formed in advance at a predetermined interval in a portion excluding a range of 10 mm backward (illustrated by h in the drawing) from the tip which becomes the upstream end surface 7 of the above. Exhaust gas circulation holes 4a and 5a are formed only in a portion excluding the upstream end portion 6 of the honeycomb structure 1 that is wound in multiple layers with the flat plate 5 being outside.

  In the present embodiment, the reason why the upstream end portion 6 is set to a range of 10 mm backward from the tip which becomes the upstream end surface 7 of the honeycomb structure 1 is related to the presence or absence of the exhaust gas flow holes 4a and 5a. In addition, as shown in FIG. 4, the catalytic reaction is accelerated rapidly behind this range as shown in FIG. 4, so that the catalyst promoting effect by exhaust gas circulation holes 4a and 5a described later is achieved. If possible, the balance between the honeycomb structure 1 and the layout of the honeycomb structure 1 may be set to a range of 10 mm or more from the tip to the rear.

  The outer cylinder 2 is formed in a cylindrical shape with a SUS430 ferritic stainless steel plate or the like having a thickness of 1 to 2 mm. The inner diameter of the cylinder is slightly smaller than the outer diameter of the honeycomb structure 1. Yes.

  The raw foil material 3 is wound around the outer peripheral surface of the honeycomb structure 1 constituted by the flat plate 5 before the honeycomb structure 1 is press-fitted into the outer cylinder 2. The raw foil material 3 is partially wound in the circumferential direction on the rear portion 8 of the honeycomb structure 1.

  Then, the honeycomb structure 1 is press-fitted into the outer cylinder 2 and heat-treated to diffusely fix the top portion of the large wave plate 4 and the flat plate 5, and the outer cylinder 2 is bonded to the honeycomb structure 1 with the low foil material 3. By fixing to the outer peripheral surface, both of these are integrated and fixed.

  As shown in FIG. 5, the metal catalyst carrier A constructed in this way is fixed by welding in a state in which a cylindrical adapter 10 is fitted on both ends of the outer cylinder 2 and a semicylindrical protector 11 is fitted on the lower side. In addition, the upstream end 6 is disposed on the engine side, and the exhaust manifold 12 is interposed at a position relatively close to the engine and used as a catalytic converter.

When exhaust gas flowing in from the engine passes through the metal catalyst carrier A, it acts on the catalyst of the large wave plate 4 and the small wave plate 5 to purify harmful substances, and passes through the rear sub-muffler 13 and the main muffler 14 to the outside. Is discharged.
At this time, the upstream end 6 becomes particularly hot compared to other parts due to high-temperature and high-speed exhaust gas flowing in from the engine side, and due to the thermal expansion / contraction caused by engine start, engine stop, acceleration / deceleration. However, as described above, since the exhaust gas flow holes 4a and 5a are not formed in the upstream end portion 6 as described above, there is no risk of being easily affected by the thermal stress, and the metal catalyst carrier. The durability of A can be improved.

  Further, the upstream end 6 can be introduced smoothly in a rectified state without increasing the exhaust resistance of the exhaust gas, and a uniform and stable catalytic action is possible.

  Further, the exhaust resistance of the exhaust gas that has passed through the upstream end 4 can be increased by the plurality of exhaust gas flow holes 4a, 5a, and the exhaust gas is exhausted backward while being promoted by the catalytic action.

  Further, in this embodiment, the raw foil material 3 for fixing the honeycomb structure 1 and the outer cylinder 2 is partially wound around the rear portion 8 of the honeycomb structure 1 in the circumferential direction. There is no possibility that the thermal stress accompanying the thermal expansion / contraction of the material will adversely affect the upstream end 6, and as described above, the temperature near the raw foil material 3 (downstream end) is higher than that of the upstream end. Since it is low, it can prevent that the fixing force of the raw foil material 3 falls by the said thermal stress.

Although the present embodiment has been described above, the present invention is not limited to the above-described embodiment, and design changes and the like within a scope not departing from the gist of the present invention are included in the present invention.
For example, in the present embodiment, the exhaust gas circulation holes 4a, 5a are formed in a long hole shape, but the shape, number of formations, and arrangement of the exhaust gas circulation holes 4a, 5a can be appropriately set.

In the present embodiment, the combination of the large wave plate 4 and the flat plate 5 has been described. However, the large wave plate 4 and the small wave plate may be combined, and the exhaust gas circulation hole is formed in at least one of these combinations. It may be structured.
In this embodiment, the metal catalyst carrier is taken as an example, but the present invention can also be applied to a ceramic catalyst carrier carrier.

It is a sectional side view which shows the metal catalyst carrier of the Example of this invention. It is a perspective view which shows the honeycomb structure of the Example of this invention. It is a perspective view which shows the state in the middle of winding a large wave plate and a flat plate. It is a figure explaining reaction distribution of the catalyst of a metal catalyst carrier. 1 is an overall view of an exhaust pipe to which a metal catalyst carrier of the present invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Honeycomb structure 2 Outer cylinder 3 Low foil material 4 Large wave plate 5 Flat plate 4a, 5a Exhaust gas flow hole 6 Upstream side end 7 Upstream side end 8 Downstream side end 10 Adapter 11 Protector 12 Exhaust manifold 13 Sub muffler 14 Main muffler

Claims (3)

A honeycomb structure housed in a metal outer cylinder is formed by alternately stacking a large corrugated plate and a corrugated plate or a flat plate of metal thin plates, and at least of the corrugated plate and the corrugated plate or the flat plate. On the other hand, in the metal catalyst carrier formed with a plurality of exhaust gas flow holes that allow the exhaust gas to flow in the radial direction of the honeycomb structure,
A metal catalyst carrier characterized in that the exhaust gas circulation holes are formed in a range excluding the upstream end of the honeycomb structure. The metal catalyst carrier according to claim 1, wherein
A metal catalyst carrier, wherein the exhaust gas circulation holes are formed in a range excluding a range of 10 mm from the upstream end face of the honeycomb structure to the rear. The metal catalyst carrier according to claim 1 or 2,
A metal characterized in that the honeycomb structure and the outer cylinder are fixed by press-fitting the honeycomb structure into the outer cylinder, winding a raw foil material at the downstream end of the honeycomb structure and heat-treating the honeycomb structure. Catalyst carrier.

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