JP2021011847A - Manufacturing method of catalyst converter - Google Patents

Abstract

To improve insertion performance when inserting a catalyst carrier wound with a holding mat into a catalyst case.SOLUTION: A catalyst converter comprises a cylindrical catalyst case 10. A catalyst carrier 20 for purifying exhaust emission is disposed in a center cylinder 13 of the catalyst case 10. A band-shaped holding mat 30 is interposed between an external peripheral face of the catalyst carrier 20 and an internal peripheral face 13A of the center cylinder 13 of the catalyst case 10 in a compressed state. In a winding step of a manufacturing method of the catalyst converter, the holding mat 30 is wound to the external peripheral face of the catalyst carrier 20. In a succeeding insertion step, the catalyst carrier 20 wound with the holding mat 30 is inserted into the center cylinder 13 of the catalyst case 10. Also, in a succeeding heating step, a part of a wall part of a portion at which the holding mat 30 in the center cylinder 13 and the catalyst carrier 20 are arranged is heated and softened, and a recess 13B progressing toward the outside at the internal peripheral face 13A of the wall part is recessed by an elastic force of the holding mat 30.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for manufacturing a catalytic converter.

Patent Document 1 describes a technique relating to a catalytic converter attached to an exhaust pipe of an internal combustion engine. The catalyst converter of Patent Document 1 includes a cylindrical catalyst case. On the inner peripheral surface of the wall portion of the catalyst case, a recess is recessed toward the outer side in the radial direction. The recesses extend all around the circumference of the catalyst case, and three recesses are arranged in the axial direction of the catalyst case. Further, the catalyst converter of Patent Document 1 includes a catalyst carrier for exhaust gas purification having a substantially cylindrical appearance. A band-shaped holding mat is wrapped around the outer peripheral surface of the catalyst carrier. Then, the catalyst carrier around which the holding mat is wrapped is inserted inside the catalyst case. In the state where the catalyst carrier is arranged inside the catalyst case in this way, the holding mat is interposed between the outer peripheral surface of the catalyst carrier and the inner peripheral surface of the catalyst case in a compressed state. A part of this holding mat is elastically deformed so as to imitate the concave portion of the wall portion of the catalyst case, and is fitted into the concave portion.

JP-A-2002-303131

In the method for manufacturing a catalyst converter of Patent Document 1, when the catalyst carrier around which the holding mat is wound is inserted into the inside of the catalyst case, the end portion of the holding mat may be caught in the recess of the wall portion of the catalyst case. Therefore, in the method for manufacturing a catalyst converter of Patent Document 1, it may take time to insert the catalyst carrier around which the holding mat is wound into the inside of the catalyst case.

A method for manufacturing a catalyst converter for solving the above problems is a tubular catalyst case, a catalyst carrier for exhaust purification arranged inside the catalyst case, an outer peripheral surface of the catalyst carrier, and the inside of the catalyst case. A method for manufacturing a catalyst converter including a band-shaped holding mat interposed between the peripheral surfaces in a compressed state, wherein the holding mat is wound around the outer peripheral surface of the catalyst carrier, and the winding. After the step, an insertion step of inserting the catalyst carrier around which the holding mat is wound into the inside of the catalyst case, and after the insertion step, a wall of a portion of the catalyst case where the holding mat and the catalyst carrier are arranged. The wall portion is softened by heating a part of the portion, and the elastic force of the holding mat is provided with a heating step of denting a concave portion toward the outside on the inner peripheral surface of the wall portion.

Since the insertion step of the above configuration is before the heating step, the holding mat does not get caught in a part of the catalyst case deformed by the heating step. Therefore, in this insertion step, it is possible to suppress a decrease in insertability when the catalyst mat around which the holding mat is wound is inserted into the inside of the catalyst case. In the subsequent heating step, a part of the wall of the catalyst case that has been heated is temporarily softened. Therefore, a part of the wall portion of the catalyst case is deformed outward by the elastic force of the holding mat, and a recess is formed on the inner peripheral surface of the wall portion. Then, the holding mat is elastically deformed so as to follow the recesses in the wall portion of the catalyst case, and a part of the holding mat is fitted. This prevents the holding mat from shifting with respect to the catalyst case, and the holding mat can hold the catalyst carrier.

Sectional view of the catalytic converter. (A) is an explanatory diagram showing a state after the insertion step. (B) is an explanatory view showing a heating process. (C) is an explanatory view showing a state after a heating step.

Hereinafter, embodiments will be described with reference to FIGS. 1 and 2. First, the configuration of the catalytic converter 100 attached to the exhaust pipe of the internal combustion engine will be described. In the following description, it is assumed that the catalytic converter 100 is attached to the exhaust pipe of the internal combustion engine, and the upstream and downstream in the exhaust flow direction are simply referred to as upstream and downstream.

As shown in FIG. 1, the catalyst converter 100 includes a tubular catalyst case 10 as a whole. The material of the catalyst case 10 is stainless steel. The first connecting cylinder 11, which is a part of the upstream side of the catalyst case 10, has a cylindrical shape. An upstream exhaust pipe of the internal combustion engine exhaust pipe is attached to the upstream end of the first connecting cylinder 11 in the catalyst case 10. From the downstream end of the first connecting cylinder 11, a diameter-expanded portion 12 having an inner diameter gradually increasing toward the downstream side extends. The inner diameter of the upstream end of the enlarged diameter portion 12 is substantially the same as the inner diameter of the first connecting cylinder 11.

A substantially cylindrical central cylinder 13 extends from the downstream end of the enlarged diameter portion 12. The inner diameter of the central cylinder 13 is substantially the same as the inner diameter of the downstream end of the enlarged diameter portion 12. Further, the inner diameter of the central cylinder 13 is substantially constant in the axial direction. The upstream end of the central cylinder 13 is fixed to the downstream end of the enlarged diameter portion 12 by arc welding.

On the inner peripheral surface 13A of the central cylinder 13, the recess 13B is recessed toward the outer side in the radial direction. The recess 13B extends over the entire circumferential direction of the central cylinder 13 and has an annular shape as a whole. The recess 13B is located at the center of the central cylinder 13 in the axial direction.

From the downstream end of the central cylinder 13, a reduced diameter portion 14 whose inner diameter gradually decreases toward the downstream side extends. The inner diameter of the upstream end of the reduced diameter portion 14 is substantially the same as the inner diameter of the central cylinder 13. The upstream end of the reduced diameter portion 14 is fixed to the downstream end of the central cylinder 13 by arc welding.

A cylindrical second connecting cylinder 15 extends from the downstream end of the reduced diameter portion 14. The inner diameter of the second connecting cylinder 15 is substantially the same as the inner diameter of the downstream end of the reduced diameter portion 14. An exhaust pipe on the downstream side of the exhaust pipe of the internal combustion engine is attached to the downstream end of the second connecting cylinder 15.

A catalyst carrier 20 for exhaust gas purification is arranged inside the central cylinder 13 in the catalyst case 10. The appearance of the catalyst carrier 20 is substantially cylindrical, and the inside of the catalyst carrier 20 has a honeycomb structure. The outer diameter of the catalyst carrier 20 is smaller than the inner diameter of the central cylinder 13 in the catalyst case 10. The axial length of the catalyst carrier 20 is substantially the same as the axial length of the central cylinder 13 in the catalyst case 10. In this embodiment, the material of the catalyst carrier 20 is aluminum oxide.

The catalyst carrier 20 is fixed to the central cylinder 13 in the catalyst case 10 via a holding mat 30 wound around the outer peripheral surface of the catalyst carrier 20. The holding mat 30 has a rectangular band shape as a whole when it is not wound around the catalyst carrier 20. The length of the holding mat 30 in the longitudinal direction is substantially the same as the length of the outer circumference of the catalyst carrier 20. The length of the holding mat 30 in the lateral direction is shorter than the length of the catalyst carrier 20 in the axial direction. Further, the thickness of the holding mat 30 in a state where it is not wound around the catalyst carrier 20 is more than half of the difference between the outer diameter of the catalyst carrier 20 and the inner diameter of the central cylinder 13 in the catalyst case 10. The holding mat 30 is formed in a band shape by molding fibers of a heat-resistant material, and is elastically deformable in the thickness direction. Therefore, the holding mat 30 is interposed between the outer peripheral surface of the catalyst carrier 20 and the inner peripheral surface of the central cylinder 13 in the catalyst case 10 in a compressed state in the thickness direction. The central portion of the holding mat 30 in the axial direction is fitted into the recess 13B of the central cylinder 13 in the catalyst case 10. In the present embodiment, the material of the holding mat 30 is aluminum oxide.

Next, a method for manufacturing the catalytic converter 100 will be described. At the start of the winding process of the method for manufacturing the catalyst converter 100 described below, the catalyst case 10 has a diameter reduction of the first connection cylinder 11 and the enlarged diameter portion 12 and the central cylinder 13. The portion 14 and the second connecting cylinder 15 are divided into three parts, that is, a fixed part.

First, in the winding step, the holding mat 30 is wound around the outer peripheral surface of the catalyst carrier 20. Specifically, the holding mat 30 is wound so that the longitudinal direction of the holding mat 30 is along the circumferential direction of the catalyst carrier 20. At this time, the holding mat 30 is arranged at the center of the catalyst carrier 20 in the axial direction.

Then, in the insertion step, the catalyst carrier 20 around which the holding mat 30 is wound is inserted into the central cylinder 13 of the catalyst case 10. Specifically, the catalyst carrier 20 around which the holding mat 30 is wound is inserted from the end of the central cylinder 13 of the catalyst case 10 and arranged at the central portion of the catalyst case 10 in the axial direction. As described above, the thickness of the holding mat 30 when not wound around the catalyst carrier 20 is more than half the difference between the outer diameter of the catalyst carrier 20 and the inner diameter of the central cylinder 13 in the catalyst case 10. ing. Therefore, in the insertion step, when the catalyst carrier 20 around which the holding mat 30 is wound is inserted into the central cylinder 13 of the catalyst case 10, the holding mat 30 is compressed in the thickness direction while being compressed with the outer peripheral surface of the catalyst carrier 20. It is interposed between the inner peripheral surface of the central cylinder 13 in the catalyst case 10. As shown in FIG. 2A, in the insertion step, the recess 13B is not recessed on the inner peripheral surface 13A of the central cylinder 13 in the catalyst case 10.

After that, as shown by the alternate long and short dash line in FIG. 2B, in the heating step, a welding nozzle (not shown) is brought closer from the radial outside of the central cylinder 13 of the catalyst case 10, and the central portion in the axial direction of the central cylinder 13 is brought closer. The walls of the wall are heated by the heat generated by arc welding. At this time, by rotating the welding nozzle relative to the central cylinder 13 in the circumferential direction of the central cylinder 13, the wall portion of the central cylinder 13 is heated over the entire circumferential direction of the central cylinder 13. By heating a part of the wall part of the central cylinder 13 in this way, the part of the wall part is softened by the heating. Then, as shown in FIG. 2C, the elastic force of the holding mat 30 acts on the softened portion of the wall portion of the central cylinder 13, so that the softened portion of the wall portion of the central cylinder 13 is formed. Is deformed outward, and a recess 13B is formed on the inner peripheral surface 13A of the central cylinder 13. Then, the holding mat 30 is elastically deformed so as to follow the recess 13B of the central cylinder 13, and the central portion of the holding mat 30 is fitted into the recess 13B of the central cylinder 13.

Further, in this heating step, at the same time as heating by arc welding, the wall portion of the central cylinder 13 of the catalyst case 10 in the axial direction is built up by arc welding. At this time, by rotating the welding nozzle relative to the central cylinder 13 in the circumferential direction of the central cylinder 13, the build-up is performed over the entire circumferential direction of the central cylinder 13. Here, the build-up is to supplement the thickness of the wall portion of the central cylinder 13 by laminating molten metal on the portion thinned by the deformation of the wall portion of the central cylinder 13 described above. In the present embodiment, the arc welding is MIG (Metal Inert Gas) welding.

After that, in the welding process, the upstream end of the central cylinder 13 and the downstream end of the enlarged diameter portion 12 are fixed by arc welding while the downstream end of the enlarged diameter portion 12 is in close contact with the upstream end of the central cylinder 13. .. Next, in the welding process, the downstream end of the central cylinder 13 and the upstream end of the reduced diameter portion 14 are fixed by arc welding while the upstream end of the reduced diameter portion 14 is in close contact with the downstream end of the central cylinder 13. To do.

The effect of this embodiment will be described.
(1) As described above, since the insertion step is before the heating step, when the catalyst carrier 20 around which the holding mat 30 is wound is inserted into the central cylinder 13 of the catalyst case 10, the recess 13B is still formed. Not formed. Therefore, when the catalyst carrier 20 around which the holding mat 30 is wound is inserted, the end portion of the holding mat 30 does not get caught in the recess 13B on the inner peripheral surface 13A of the central cylinder 13. Therefore, in the insertion step, it is possible to suppress a decrease in insertability when the catalyst carrier 20 around which the holding mat 30 is wound is inserted into the central cylinder 13 of the catalyst case 10.

In the subsequent heating step, as shown in FIG. 2C, the recess 13B is formed on the inner peripheral surface 13A of the central cylinder 13. Then, the holding mat 30 is elastically deformed so as to follow the recess 13B of the central cylinder 13, and the central portion of the holding mat 30 is fitted into the recess 13B of the central cylinder 13. By fitting the central portion of the holding mat 30 into the recess 13B of the central cylinder 13 in this way, the holding mat 30 is displaced from the central cylinder 13 of the catalyst case 10 in the axial direction of the central cylinder 13. Can be suppressed.

(2) In the present embodiment, in the heating step, the recess 13B is recessed over the entire circumferential direction of the central cylinder 13. The central portion of the holding mat 30 in the axial direction is fitted into the recess 13B over the entire circumferential direction. Therefore, the central portion of the holding mat 30 in the axial direction is uniformly compressed in the circumferential direction of the central cylinder 13 between the outer peripheral surface of the catalyst carrier 20 and the inner peripheral surface 13A of the central cylinder 13. As a result, the holding mat 30 is supported by a uniform force in the circumferential direction of the central cylinder 13 between the outer peripheral surface of the catalyst carrier 20 and the inner peripheral surface 13A of the central cylinder 13. As a result, the catalyst carrier 20 is stably held in the central cylinder 13 of the catalyst case 10 via the holding mat 30.

(3) The holding mat 30 is fitted in the recess 13B in the central cylinder 13 of the catalyst case 10. Here, when the holding mat 30 vibrates with respect to the central cylinder 13 of the catalyst case 10 due to the pulsation of the circulating exhaust gas or the like, the holding mat 30 is brought into contact with a part of the holding mat 30 and the edge of the recess 13B of the central cylinder 13. Some fibers may be unraveled. When the fibers of the holding mat 30 are unraveled in this way, the fibers of the holding mat 30 may flow through the exhaust passage together with the exhaust gas flowing through the exhaust passage.

In this respect, in the present embodiment, the central portion of the holding mat 30 in the axial direction is fitted in the recess 13B of the central cylinder 13. Therefore, the portion of the holding mat 30 on the upstream side of the central portion in the axial direction and the portion on the downstream side of the central portion are in close contact with the inner peripheral surface 13A of the central cylinder 13 in a compressed state. As a result, even if the fibers in the central portion in the axial direction of the holding mat 30 are unraveled, the fibers do not go out to the outside of the recess 13B of the central cylinder 13. As a result, it is possible to prevent the fibers of the holding mat 30 from flowing through the exhaust passage together with the exhaust gas flowing through the exhaust passage.

(4) In the heating step, as shown in FIG. 2C, the elastic force of the holding mat 30 acts on the softened portion of the wall portion of the central cylinder 13, so that the wall portion of the central cylinder 13 is affected. Our softened part deforms outward. When the wall portion of the central cylinder 13 is deformed in this way, the thickness of a part of the wall portion of the central cylinder 13 may be reduced.

In this respect, in the present embodiment, in the heating step, the wall portion of the central cylinder 13 of the catalyst case 10 is built up at the same time as heating by arc welding. Therefore, in the heating step, even if the wall portion of the central cylinder 13 is deformed toward the outside and the thickness of a part of the wall portion of the central cylinder 13 is reduced, the thickness of the wall portion of the central cylinder 13 is increased by overlaying. Is supplemented. As a result, it is possible to prevent the thickness of a part of the wall portion of the central cylinder 13 from becoming thin.

This embodiment can be modified and implemented as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
-In the above embodiment, the heating process can be changed. For example, in the circumferential direction of the central cylinder 13 in the catalyst case 10, a part of the central cylinder 13 in the circumferential direction may be heated. In this case, the recess 13B is formed in a part of the central cylinder 13 in the circumferential direction.

-In the above embodiment, the upstream side of the central portion of the central cylinder 13 in the axial direction and the downstream side of the central portion of the central cylinder 13 in the axial direction may be heated. Also in this case, if the wall portion of the central cylinder 13 where the catalyst carrier 20 and the holding mat 30 are arranged is heated, the elastic force of the holding mat 30 acts on the softened portion of the wall portion of the central cylinder 13.

-In the above embodiment, it is not necessary to heat the central cylinder 13 along the circumferential direction. For example, heating may be performed along the axial direction of the central cylinder 13. Further, for example, the central cylinder 13 may be heated from one side in the circumferential direction to the other side in the circumferential direction while being curved with respect to the circumferential direction of the central cylinder 13. As a specific example, the welding nozzle is moved so as to be curved in a substantially S shape with respect to the central cylinder 13 to heat the wall portion of the central cylinder 13, or the welding nozzle is substantially Z-shaped with respect to the central cylinder 13. The wall portion of the central cylinder 13 may be heated by moving it so as to be bent.

-In the above embodiment, a plurality of locations of the central cylinder 13 may be heated intermittently. For example, the wall portion of the central cylinder 13 may be heated intermittently in the circumferential direction of the central cylinder 13. When the wall portion of the central cylinder 13 is heated intermittently in this way, it is preferable to heat the wall portion of the central cylinder 13 while avoiding the end portion in the longitudinal direction of the holding mat 30. Similarly, the wall portion of the central cylinder 13 may be heated intermittently in the axial direction of the central cylinder 13.

-In the above embodiment, the overlay may be omitted in the heating step. For example, if the strength of the central cylinder 13 is sufficiently high due to the depth of the recess 13B, the thickness of the central cylinder 13, and the like, the build-up may be omitted.

-In the above embodiment, the heating method can be changed in the heating step. For example, not limited to arc welding, the wall portion of the central cylinder 13 may be heated by laser welding. Further, for example, the wall portion of the central cylinder 13 may be heated by another method, not limited to heating by welding.

-In the above embodiment, the fixing order in the welding process can be changed. For example, after fixing the downstream end of the central cylinder 13 and the upstream end of the diameter reduction portion 14, the upstream end of the central cylinder 13 and the downstream end of the diameter expansion portion 12 may be fixed.

-In the above embodiment, the welding process can be changed according to the state of the catalyst case 10 at a time point before the insertion process. For example, at a time prior to the insertion step, the catalyst case 10 has a component to which the first connecting cylinder 11 and the enlarged diameter portion 12 are fixed, and the central cylinder 13, the reduced diameter portion 14, and the second connecting cylinder 15 are fixed. It is assumed that the parts are divided into two parts. In this case, in the welding step, it is only necessary to fix the upstream end of the central cylinder 13 and the downstream end of the enlarged diameter portion 12 by arc welding.

Further, for example, at a time prior to the insertion step, the catalyst case 10 includes a part to which the first connecting cylinder 11, the diameter-expanding portion 12, and the central cylinder 13 are fixed, the diameter-reducing portion 14, and the second connecting cylinder. It is assumed that 15 is divided into two parts, a fixed part and a fixed part. In this case, in the welding step, it is only necessary to fix the downstream end of the central cylinder 13 and the upstream end of the reduced diameter portion 14 by arc welding.

Further, for example, at a time before the insertion step, the catalyst case 10 includes the first connecting cylinder 11, the diameter-expanded portion 12, the central cylinder 13, the diameter-reduced portion 14, and the second connecting cylinder 15. Even if it is divided into three parts, in the welding process, five parts, the first connecting cylinder 11, the enlarged diameter portion 12, the central cylinder 13, the reduced diameter portion 14, and the second connecting cylinder 15, are fixed. do it. Therefore, at a time before the insertion step, the upstream end of the central cylinder 13 of the catalyst case 10 is not fixed to the downstream end of the diameter-expanded portion 12, or the downstream end of the central cylinder 13 of the catalyst case 10 is not fixed. It may not be fixed to the upstream end of the reduced diameter portion 14.

-In the above embodiment, the fixed configuration of the central cylinder 13 and the enlarged diameter portion 12 and the fixed configuration of the central cylinder 13 and the reduced diameter portion 14 can be changed. For example, the central cylinder 13 and the enlarged diameter portion 12 may be fixed by adhesion with their end portions in close contact with each other. That is, in this case, the bonding process may be adopted instead of the welding process.

10 ... catalyst case, 11 ... first connecting cylinder, 12 ... enlarged diameter portion, 13 ... central cylinder, 13A ... inner peripheral surface, 13B ... concave portion, 14 ... reduced diameter portion, 15 ... second connecting cylinder, 20 ... catalyst carrier , 30 ... Retention mat, 100 ... Catalytic converter.

Claims (1)

A tubular catalyst case, a catalyst carrier for exhaust gas purification arranged inside the catalyst case, and a compressed state are interposed between the outer peripheral surface of the catalyst carrier and the inner peripheral surface of the catalyst case. A method of manufacturing a catalytic converter having a strip-shaped holding mat.
A winding step of winding the holding mat around the outer peripheral surface of the catalyst carrier, and
After the winding step, an insertion step of inserting the catalyst carrier around which the holding mat is wound into the catalyst case, and an insertion step.
After the insertion step, the holding mat in the catalyst case and a part of the wall portion of the portion where the catalyst carrier is arranged are heated to soften the wall portion, and the elastic force of the holding mat causes the wall portion to be softened. A method for manufacturing a catalytic converter, which comprises a heating step of denting a concave portion toward the outside on the inner peripheral surface.