JP2009127604A - Catalytic converter and manufacturing method thereof - Google Patents

Abstract

A tandem type catalytic converter that accommodates catalyst carriers in a series arrangement, and a catalytic converter capable of reliably ensuring the required flatness of a flat surface of a reduced diameter portion, and a method of manufacturing the same are provided.
SOLUTION: A catalyst carrier 3 is accommodated in a cylindrical casing 2 in a series arrangement, and a flat surface 232 serving as a sensor mounting seat is provided at a position corresponding to the space between the catalyst carriers 3 and 3 of the casing 2. This is a tandem type catalytic converter 1 that forms a diameter portion 23. The position corresponding to the space between the catalyst carriers 3 and 3 of the casing 2 is reduced by spinning, and the reduced diameter portion is pressed. The reduced diameter portion 23 having the flat surface 232 is formed.
[Selection] Figure 2

Description

  The present invention relates to a tandem catalytic converter in which a catalyst carrier is accommodated in a cylindrical casing in a series arrangement and a method for manufacturing the same.

  As a tandem type catalytic converter that accommodates catalyst carriers in a cylindrical casing in a series arrangement, a reduced diameter portion having a flat surface serving as a mounting seat for the sensor is formed at a position corresponding to between the catalyst carriers of the casing. Things are known. The catalytic converter uses a cylindrical material corresponding to the diameter of the accommodating portion in which the catalyst carrier is accommodated, attaches the cylindrical material to the inner mold, moves a plurality of split molds to the inner mold side, and presses the cylindrical material By forming a reduced diameter portion having a flat surface as a mounting seat, the catalyst carrier is accommodated in accommodating portions located on both sides of the reduced diameter portion, and guide members having cone portions at both ends of the cylindrical material are welded. (See Patent Document 1).

JP 2004-92461 A

  By the way, the catalytic converter forms the flat surface and the curved surface of the reduced diameter portion by pressing the inner mold and the plurality of split molds, but the thickness of the cylindrical material concentrates on the processed portion at the time of pressing, In order to obtain a flat surface with high flatness, for example, it is necessary to perform processing while forming a concave groove or a ridge to compensate for a difference in circumferential length between the flat surface of the reduced diameter portion and the curved surface. However, even if the groove or the ridge is provided, there may be cases where sufficient flatness cannot be obtained on the flat surface depending on the diameter of the cylindrical material. Cannot be attached by projection welding or the like.

  In addition, when press working is performed with a large number of split molds as in Patent Document 1, a large number of split molds corresponding to each diameter are prepared and changed when manufacturing various types of catalytic converters having different diameters of the reduced diameter portions. Therefore, the manufacturing cost becomes expensive and the labor required for the manufacturing increases.

  The present invention is proposed in view of the above-described problems, and is a tandem type catalytic converter that accommodates catalyst carriers in series, and can ensure the required flatness of the flat surface of the reduced diameter portion. And it aims at providing the manufacturing method. Another object of the present invention is to provide a catalytic converter capable of reducing the manufacturing cost and the labor required for manufacturing, and a manufacturing method thereof.

  The catalytic converter of the present invention accommodates catalyst carriers in a substantially cylindrical casing in series, and has a reduced diameter having a flat surface that serves as a mounting seat for the sensor at a position corresponding to the space between the catalyst carriers of the casing. A tandem type catalytic converter for forming a portion, wherein the reduced diameter portion having the flat surface is formed by pressing a portion reduced in diameter by spinning.

  In addition, the catalytic converter of the present invention is characterized in that it smoothly transitions from the flat surface of the reduced diameter portion to the curved surface of the reduced diameter portion.

  Further, the catalytic converter of the present invention is characterized in that an inner peripheral surface of the reduced diameter portion is disposed inside a holding material that is provided on an outer periphery of the catalyst carrier and holds the catalyst carrier.

  Further, in the method for manufacturing the catalytic converter of the present invention, the catalyst carriers are accommodated in series in a substantially cylindrical casing, and the sensor mounting flat is provided at a position corresponding to the space between the catalyst carriers of the casing. A method of manufacturing a tandem type catalytic converter for forming a reduced diameter portion having a surface, wherein a position corresponding to the space between the catalyst carriers of a cylindrical material to be the casing is subjected to a spinning process to reduce the diameter. And a second step of forming a reduced diameter portion having the flat surface by pressing the reduced diameter portion in the first step.

  Further, in the method for manufacturing the catalytic converter of the present invention, in the second step, the flat surface is formed while maintaining the diameter of the curved surface of the reduced diameter portion reduced in the first step. Features.

  In the method for manufacturing a catalytic converter according to the present invention, after the second step, a mounting hole is formed in the flat surface of the reduced diameter portion, and a sensor mounting tool is inserted into the mounting hole to A hook-shaped part is disposed so as to abut on the flat surface, and a process of performing projection welding between the hook-shaped part of the fixture and the flat surface is provided.

  The catalytic converter of the present invention is preferably provided in the exhaust path of the internal combustion engine in the exhaust structure of the internal combustion engine, such as provided in the exhaust path of the engine of an automobile. Further, the number of catalyst carriers arranged in series in the present invention can be an appropriate number of two or more, such as three or four. In addition to the configurations of the inventions and embodiments, the invention disclosed in this specification includes those specified by changing these partial configurations to other configurations disclosed in this specification, or these configurations. To which other configurations disclosed in the present specification are added and specified, or those partial configurations that have been deleted and specified to the extent that partial effects can be obtained are included.

  In the present invention, the reduced diameter portion of the casing is reduced in diameter by spinning, and the reduced diameter portion is pressed to form a reduced diameter portion having a flat surface. Then, the thickness of the portion reduced in diameter during the spinning process escapes to both ends of the cylindrical material constituting the casing, and the thickness of the reduced diameter part also escapes to both ends of the cylindrical material during subsequent pressing. Wrinkles are less likely to occur on the reduced diameter portion and its flat surface. Therefore, it is not necessary to form a groove or a ridge to compensate for the circumferential length difference, and a reduced diameter portion having a flat surface with a required flatness such as a flatness of 0.3 mm or less can be obtained easily and reliably. . Therefore, the fixture of the sensor and the flat surface can be securely fixed by projection welding or the like, and there is no such thing that the protruding line becomes an obstacle when installed in the exhaust path of the internal combustion engine, It can be reliably installed in the exhaust path of the internal combustion engine.

  Further, for example, by reducing the diameter by spinning processing, the reduced diameter portion is pressed with an inner mold and a pressing die having a portion corresponding to the flat surface to form a flat surface of the reduced diameter portion. By maintaining the diameter of the curved surface of the reduced diameter portion and forming a flat surface by pressing, a wide variety of catalytic converters with different diameters can be reduced without using many split molds. It can be manufactured at low cost and labor.

  In addition, by adopting a structure that smoothly transitions from a flat surface to a curved surface of the reduced diameter portion, it becomes possible to manufacture without using a mold that forms a concave groove or ridge to compensate for the difference in circumference. Cost can be reduced.

  Further, by disposing the inner peripheral surface of the reduced diameter portion inside the holding material that is provided on the outer periphery of the catalyst carrier and holds the catalyst carrier, it is possible to prevent scattering of the holding material and alteration of the holding material as much as possible. Can do.

  Embodiments of a catalytic converter and a method for producing the same according to the present invention will be described.

  The catalytic converter 1 of the present embodiment is a tandem type catalytic converter in which catalyst carriers are arranged in series. As shown in FIGS. 1 to 3, the catalytic converter 1 is separated from the substantially cylindrical casing 2 and the casing 2. Two catalyst carriers 3 accommodated in a series arrangement, a holding member 4 for holding the catalyst carrier 3 in the casing 2, and a sensor fixture 5 such as an oxygen sensor attached to the casing 2 are provided.

  The casing 2 is provided with an accommodating portion 21 in which the catalyst carrier 3 is accommodated at two positions in the longitudinal direction. The accommodating portion 21 has a diameter slightly larger than the diameter of the catalyst carrier 3. It is formed with a length corresponding to the length of the body 3. Between the accommodating portions 21 and 21 corresponding to the position between the catalyst carriers 3 and 3, it is located between the tapered portion 22 and the tapered portions 22 and 22 that are reduced in diameter from the inner end of the accommodating portion 21 toward the center. A reduced diameter portion 23 is formed.

  The reduced diameter portion 23 has a shape in which a flat surface 232 serving as a mounting seat for the sensor fixture 5 is formed on the upper surface of a circumferential curved surface 231 in a cross-sectional view. There is no groove or ridge projecting outward at the boundary, and the shape smoothly transitions from the flat surface 232 to the curved surface 231. The inner surfaces of the curved surface 231 and the flat surface 232, which are the inner peripheral surfaces of the reduced diameter portion 23, are formed so as to be arranged on the inner side of the holding material 4 holding the catalyst carrier 3 described later. The reduced-diameter portion 23 having the flat surface 232 is formed by pressing a portion that has been reduced in diameter by spinning as described later. Further, a mounting hole 233 of a sensor mounting tool 5 to be described later is formed in the approximate center of the flat surface 232.

  Cone portions 24 are formed at both ends of the casing 2, respectively. The cone portions 24 are formed so as to taper outward from the outer end of the accommodating portion 21. A cylindrical opening is formed at the tip of the cone portion 24. A portion 241 is formed.

  The catalyst carrier 3 is wound around the outer periphery with the holding material 4 and is accommodated in each accommodating portion 21, and the retaining material is interposed between the inner peripheral surface of the accommodating portion 21 and the outer peripheral surface of the catalyst carrier 3. 4, the catalyst carrier 3 is held in the accommodating portion 21. The catalyst carrier 3 may be a monolithic catalyst carrier or the like, and the holding material 4 may be a cushion material having a buffer function such as ceramic fibers.

  The sensor attachment 5 has a substantially ring shape with a step on the outer periphery, and has a small diameter part 51 and a large diameter part 52, and an attachment hole 53 having a female thread formed in the peripheral surface is provided at the center. (See FIG. 9). The small diameter portion 51 of the fixture 5 has substantially the same diameter as the mounting hole 233 of the flat surface 232, the small diameter portion 51 is inserted into the mounting hole 233, and the large diameter portion 52 is placed in contact with the flat surface 232. The fixture 5 and the casing 2 are fixed to each other by welding the large diameter portion 52 and the flat surface 232 by projection welding described later. A male screw portion of a sensor (not shown) is screwed into the mounting hole 53 which is a screw hole of the mounting tool 5, and the sensor is attached to the catalytic converter 1 by the screwing.

  Next, a method for manufacturing the catalytic converter 1 will be described.

  As a member constituting the casing 2, a cylindrical material 200 having a diameter corresponding to the diameter of the accommodating portion 21 shown in FIG. 4 is used. Then, as shown in FIG. 5, the diameter-reduced portion 23 of the casing 2 is formed by the molding roller 12 that holds one side of the cylindrical material 200 with the clamp 11 of the spinning processing apparatus and is arranged in a plurality in the circumferential direction. A diameter-reduced portion 203a that is substantially concentric with the cylindrical material 200 in a cross-sectional view and reduced in diameter to a substantially perfect circle is formed in a substantially central portion of the cylindrical material 200 corresponding to the portion. The forming roller 12 can rotate and revolve in the circumferential direction, and can move in the radial direction of the cylindrical member 200. When forming the reduced diameter portion 203a by spinning, the forming roller 12 is brought into contact with the outer peripheral surface of the cylindrical material 200, and the forming roller 12 is moved toward the central axis of the cylindrical material 200 while rotating and revolving. A reduced diameter portion 203a having substantially the same width as the roller 12 is formed. Along with the formation of the reduced diameter portion 203a, tapered portions 202 are formed on both sides of the reduced diameter portion 203a.

  Instead of using the molding roller 12 having the same width as that of the reduced diameter portion 203a, a molding roller 121 having a smaller width than the reduced diameter portion 203a is used as shown in FIG. The diameter-reduced portion 203a may be formed by moving in the radial direction while moving in the direction. For example, as shown in FIG. 10, the forming roller 121 is disposed at a position corresponding to one end of the reduced diameter portion 203 a in the longitudinal direction of the cylindrical material 200, and the forming roller 121 is moved in the radial direction of the cylindrical material 200. The cylindrical roller 200 is pressed to reduce the diameter (see FIG. 10A), and the forming roller 121 is moved to a position corresponding to the other end of the reduced diameter portion 203a while maintaining the radial position. A reduced diameter portion 2031 is formed over the entire corresponding region of the portion 203a (see FIG. 10B). Next, at a position corresponding to the other end portion, the forming roller 121 is further moved in the radial direction of the cylindrical material 200 and pressed against the cylindrical material 200 to reduce the diameter, and the one end portion remains in the radial position. The forming roller 121 is moved to a position corresponding to the above, and a reduced diameter part is further reduced over the entire corresponding region of the reduced diameter part 203a. The movement of the forming roller 121 at the one end and the other end is repeated a plurality of times to form a reduced diameter portion 203a having a predetermined diameter. The diameter reduction processing is preferable because the thickness of the cylindrical material 200 in the diameter reduction portion 203a can be released to each end side of the diameter reduction portion 203a in a well-balanced manner. Further, instead of the configuration in which the forming roller 12 is revolved, the cylindrical material 200 may be rotated in the circumferential direction while being held by the clamp 11.

  After that, as shown in FIG. 6, the cylindrical material 200 is externally fitted to the inner mold 13 of the press working apparatus, and the reduced diameter portion 203 a of the cylindrical material 200 is disposed so as to be supported by the inner mold 13. In the arrangement state, the flat portion 131 on the upper surface of the inner mold 13 is arranged at a position corresponding to the formation position of the flat surface 2032 of the cylindrical material 200 described later. Then, the lower half of the reduced diameter portion 203a is supported by the pad 15 in a cross sectional view, and the concave pressing die 14 is lowered from the upper half of the reduced diameter portion 203a to press the reduced diameter portion 203a. A flat surface 2032 is formed by press working at a position corresponding to the flat portion 131 and the flat portion 141 of the pressing die 14, and the reduced diameter portion 203 having the flat surface 2032 is formed on the upper surface of the curved surface 2031. As in this example, it is preferable that only the flat surface 2032 is formed in the substantially circular reduced diameter portion 203a in the press working. However, for example, the reduced diameter portion 203a is further changed during press working using a split mold. It is also possible to form the flat surface 2032 while reducing the diameter.

  After that, as shown in FIG. 7, the extraction table 16 is disposed inside the reduced diameter portion 203 of the cylindrical member 200 so as to contact the flat surface 2032, and corresponds to the extraction hole 161 of the extraction table 16. The punch 17 is disposed outside the reduced diameter portion 203, the punch 17 is lowered to the punching hole 161, and substantially the center of the flat surface 2032 is punched, and the mounting hole 2033 of the sensor mounting tool 5 is formed by piercing.

  Next, as shown in FIG. 8, the small-diameter portion 51 of the sensor fixture 5 is inserted into the attachment hole 2033, and the bottom surface of the large-diameter portion 52 protruding in a bowl shape (the bowl-shaped portion) is the top surface of the flat surface 2032. The projecting portion of the large diameter portion 52 and the flat surface 2032 are fixed by projection welding. When performing the projection welding, as shown in FIG. 9, the lower electrode 18 is brought into contact with the lower surface of the flat surface 2032 at a position where the protruding portion of the large diameter portion 52 and the flat surface 2032 overlap each other. The upper electrode 19 is brought into contact with a position corresponding to the lower electrode 18 of the diameter portion 232, and a current is passed through the electrodes 18, 19 to weld the protruding portion of the large diameter portion 232 and the flat surface 2032.

  Further, the catalyst carrier 3 around which the holding material 4 is wound is inserted and accommodated on both sides of the reduced diameter portion 203 of the cylindrical material 200 (see FIG. 8). Then, the cylindrical member 200 is held by a clamp of a spinning processing device (not shown), and the cylindrical member 200 is subjected to spinning processing with molding rollers at both ends in the longitudinal direction to form a cone portion 24 having a cylindrical opening 241. The catalytic converter 1 shown in FIGS. 1 and 2 is completed. Thereafter, a sensor is attached to the attachment 5 of the catalytic converter 1 by screwing into the attachment hole 53.

  In the manufacturing process of the catalytic converter 1, when the reduced diameter portion 203 a is formed by spinning, the thickness of the reduced diameter portion 203 escapes to both ends of the cylindrical material 200, and the thickness escapes also during subsequent pressing. Following the above flow, the thickness of the reduced diameter portion 203 escapes to both ends of the cylindrical material 200, and the reduced diameter portions 23, 203 and their flat surfaces 232, 2032 are not easily wrinkled. Therefore, the reduced diameter portion 23 having the flat surface 232 having the required flatness can be obtained easily and reliably without forming a groove or a ridge for compensating for the difference in circumference. In addition, since the required flatness can be reliably ensured on the flat surface 232, the fixture 5 and the flat surface 232 can be reliably welded during projection welding. In addition, since a large number of split molds are not used, a wide variety of catalytic converters 1 having different diameters of the reduced diameter portion 23 can be manufactured with low cost and labor.

  The present invention can be used as, for example, a catalytic converter provided in an exhaust path of an automobile engine.

The top view of the catalytic converter of an embodiment. The longitudinal cross-sectional view of the catalytic converter of embodiment. The cross-sectional view in the reduced diameter part of the catalytic converter of embodiment. The longitudinal cross-sectional view of a cylindrical material. (A) is a longitudinal cross-sectional view which shows the cylindrical material to which a spinning process is given, (b) is a cross-sectional view which shows the reduced diameter part of the cylindrical material of the same figure (a). (A) is a longitudinal cross-sectional view which shows the cylindrical material by which a reduced diameter part is pressed, (b) is a cross-sectional view which shows the reduced diameter part of the cylindrical material of the figure (a). (A) is a longitudinal cross-sectional view which shows the cylindrical material by which the diameter reduction part is pierced, (b) is a cross-sectional view which shows the diameter reduction part of the cylindrical material of the figure (a). The longitudinal cross-sectional view which shows the state by which the sensor fixture and the catalyst carrier were provided in the cylindrical material to which the piercing process was given. Partial explanatory drawing explaining the process of adhering a sensor fixture to a flat-surface attachment hole by projection welding. (A), (b) is a longitudinal cross-sectional view which shows a part of cylindrical material in which the spinning process of a modification is given.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Catalytic converter 2 ... Casing 200 ... Cylindrical material 21 ... Accommodating part 22, 202 ... Tapered part 23, 203, 203a, 2031 ... Reduced diameter part 231, 2031 ... Curved surface 232, 2032 ... Flat surface 233, 2033 ... Mounting hole 24 ... Cone 241 ... Opening 3 ... Catalyst carrier 4 ... Holding material 5 ... Mounting tool 51 ... Small diameter part 52 ... Large diameter part 53 ... Mounting hole 11 ... Clamp 12, 121 ... Forming roller 13 ... Inner mold 14 ... Pushing tool 131 , 141 ... plane part 15 ... pad 16 ... punching table 161 ... punching hole 17 ... punch 18 ... lower electrode 19 ... upper electrode

Claims (6)

A tandem type of accommodating a catalyst carrier in a substantially cylindrical casing in a serial arrangement and forming a reduced diameter portion having a flat surface as a mounting seat for a sensor at a position corresponding to the space between the catalyst carriers of the casing. A catalytic converter,
A catalytic converter, wherein the reduced diameter portion having the flat surface is formed by pressing a reduced diameter portion by spinning.   The catalytic converter according to claim 1, wherein the catalytic converter is configured to smoothly transition from a flat surface of the reduced diameter portion to a curved surface of the reduced diameter portion.   3. The catalytic converter according to claim 1, wherein an inner peripheral surface of the reduced diameter portion is disposed on an inner side of a holding material that is provided on an outer periphery of the catalyst carrier and holds the catalyst carrier. A tandem type of accommodating a catalyst carrier in a substantially cylindrical casing in a serial arrangement and forming a reduced diameter portion having a flat surface as a mounting seat for a sensor at a position corresponding to the space between the catalyst carriers of the casing. A method for manufacturing a catalytic converter, comprising:
A first step of reducing the diameter by applying a spinning process to a position corresponding to between the catalyst carriers of the cylindrical material serving as the casing;
And a second step of forming a reduced diameter portion having the flat surface by pressing the reduced diameter portion in the first step.   5. The production of the catalytic converter according to claim 4, wherein in the second step, the flat surface is formed while maintaining a diameter of a curved surface of the reduced diameter portion reduced in the first step. Method.   After the second step, a mounting hole is formed in the flat surface of the reduced diameter portion, and a sensor mounting tool is inserted into the mounting hole so that the hook-shaped portion of the mounting tool abuts the flat surface. 6. The method of manufacturing a catalytic converter according to claim 4, further comprising a step of performing projection welding on the hook-shaped portion of the fixture and the flat surface.

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