JP2006242033A - Exhaust pipe joint structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust pipe joint structure preventing damage of a part near a welding part of an exhaust pipe and a joint flange and easily absorbing axial position slippage of the exhaust pipe by the joint flange. <P>SOLUTION: This exhaust pipe joint structure is provided with a taper part 4 expanding toward a terminal and a cylindrical large diameter pipe part 6 connecting from the taper part 4 via a second bent part 5 on one end part of the exhaust pipe, has the large diameter pipe part 6 of the exhaust pipe 1 fitted into an insertion hole 11 from a sleeve side 10 formed on one surface of the joint flange 7, and has a sleeve tip 101 of the joint flange 7 arranged near a second bend part 5 and welded on the exhaust pipe 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust pipe joint structure that welds an exhaust pipe and a joint flange used in, for example, an automobile, and more particularly to prevent damage to the exhaust pipe and reduce the weight of the exhaust pipe in the vicinity of the welded portion between the exhaust pipe and the joint flange. It is related with the exhaust pipe joint structure which can aim at.

  Regarding the structure for welding the exhaust pipe and joint flange of an automobile, there is a structure of Patent Document 1. In Patent Document 1, a tapered portion provided on a joint flange and a tapered portion provided on an end of an exhaust pipe are fitted, and one tapered portion end and the other tapered portion are fitted on the fitting inner surface side between the tapered portions. A structure in which the joint flange and the exhaust pipe are joined by welding is disclosed, and it is said that cracks in the vicinity of the welded portion between the exhaust pipe and the joint flange can be prevented.

No. 5-13940

  By the way, a long exhaust pipe or an exhaust pipe that has been subjected to processing such as bending in the middle is arranged with one end at the reference position due to variations in processing and an error in the length of the exhaust pipe. When connecting, an axial shift is likely to occur at the position where the exhaust pipe end is disposed. For this reason, it is desirable to absorb such displacement in the axial direction of the exhaust pipe at the connection location by the joint flange.

  However, in the structure in which the tapered portion of Patent Document 1 is fitted, if there is a displacement in the axial direction of the exhaust pipe, the tapered portion of the joint flange and the tapered portion of the exhaust pipe are separated, or a gap is formed, or It becomes difficult for both sides to carry and overlap, making it difficult to absorb axial misalignment. Furthermore, since it is necessary to taper both the exhaust pipe end and the joint flange, the structure of Patent Document 1 requires labor for processing and increases the manufacturing cost. Therefore, there is a demand for a structure that can solve such problems.

  The present invention proposes to solve the above-mentioned problems, and it is possible to prevent the exhaust pipe from being damaged in the vicinity of the welded portion between the exhaust pipe and the joint flange and to prevent the displacement of the exhaust pipe in the axial direction with the joint flange. It is another object of the present invention to provide an exhaust pipe joint structure that can be easily absorbed and can be manufactured with low labor and low cost.

  The exhaust pipe joint structure of the present invention is provided at one end of the exhaust pipe with a tapered portion that expands toward the end, and a cylindrical large-diameter pipe portion that continues from the tapered portion through the bent portion, Fit the large-diameter pipe part of the exhaust pipe into the insertion hole of the joint flange, and place the end of the insertion hole of the joint flange in the vicinity of the bent part interposed between the taper part and the large-diameter pipe part. It arrange | positions in and is welded to an exhaust pipe. Further, when a sleeve is formed on one side of the joint flange and the end of the insertion hole of the joint flange is the tip of the sleeve, the tip of the sleeve is arranged in the vicinity of the bent portion to the exhaust pipe. It is characterized by welding. Further, it is preferable that the inclination angle of the taper portion is 20 degrees to 60 degrees, because the stress can be more effectively dispersed and the strength can be increased.

  The bent portion interposed between the taper portion and the large-diameter tube portion corresponds to a second bent portion in an embodiment described later, and the bent portion or the large-diameter tube near the bent portion is in the vicinity of the bent portion. Part, a taper part near the bent part, or an appropriate combination thereof. The joint flange preferably has a sleeve in order to ensure stable holding of the exhaust pipe, but may have no sleeve. Further, the end of the insertion hole of the joint flange includes an end other than the tip of the sleeve constituting the insertion hole. For example, when the insertion hole is formed in the flat flange portion, one end of the flange portion is formed. The end of the insertion hole is also included.

  In the exhaust pipe joint structure of the present invention, the cylindrical large-diameter pipe portion of the exhaust pipe is fitted into the insertion hole of the joint flange, so that the axial displacement of the exhaust pipe due to processing error, design error, etc. The length by which the large-diameter pipe portion is inserted into the insertion hole can be appropriately adjusted and absorbed easily.

  In addition, by disposing the end of the insertion hole of the joint flange, preferably the end of the sleeve in the vicinity of the bent portion and welding it to the exhaust pipe, it is possible to distribute the stress at the tapered portion of the exhaust pipe, etc. The strength in the vicinity of the welded portion between the joint flange and the joint flange can be greatly increased to prevent the exhaust pipe from being damaged. Furthermore, since an extremely high strength can be obtained even with a thin exhaust pipe, the exhaust pipe can be significantly reduced in weight.

  In addition, since the taper part is provided only at the end of the exhaust pipe and the taper part is not provided on the joint flange, it is possible to reduce the labor required for machining work and to manufacture and supply at low cost. can do.

  The exhaust pipe joint structure of the present invention will be described based on an embodiment of an exhaust pipe joint structure including an automobile exhaust pipe and a joint flange shown in FIGS.

  The exhaust pipe 1 for an automobile in the present embodiment is substantially cylindrical as a whole, and one end portion of the exhaust pipe 1 connected to the cylindrical small diameter pipe portion 2 is directed toward the end of the exhaust pipe 1. A taper portion 4 that expands while rising from the first bend portion 3, a second bend portion 5 that bends horizontally from the end of the taper portion 4, and a continuous portion from the taper portion 4 through the second bend portion 5; A cylindrical large-diameter pipe portion 6 formed to the end of the exhaust pipe 1 is provided.

  The thickness of the exhaust pipe 1 of this example is 1.0 mm, the inclination angle of the taper part 4 is about 20 degrees, the outer diameter of the small diameter pipe part 2 is 45 mm, the outer diameter of the large diameter pipe part 6 is 48.6 mm, and the large diameter. The length of the pipe part 6 is 10 mm. The distance between the second bent portion 5 or a welded portion 12 (to be described later) and the first bent portion 3 is preferably set to such a distance that the heat effect of welding does not appear on the first bent portion 3, for example, 5 mm to 30 mm. The inclination angle of the taper portion 4 is preferably 20 degrees to 60 degrees.

  The joint flange 7 has a flange portion 8 having a substantially triangular shape when viewed from the front, and bolt holes 9 into which connecting bolts are inserted are formed in the vicinity of the corners of the triangle. A sleeve 10 that is a circumferential protrusion is formed at the center of one surface of the flange portion 8, and holes formed at positions corresponding to the inside of the sleeve 10 and the inside of the sleeve 10 of the flange portion 8 are described later. The exhaust hole 1 is inserted into the insertion hole 11, and the inner diameter of the insertion hole 11 and the outer diameter of the large diameter pipe part 6 are substantially the same.

  The large-diameter pipe portion 6 of the exhaust pipe 1 is inserted from the sleeve 10 side into the insertion hole 11 of the joint flange 7, and the sleeve 10 is disposed outside the large-diameter pipe portion 6 of the exhaust pipe 1. And the front-end | tip 101 of the sleeve 10 is fitted by the exhaust pipe 1 so that it may be arrange | positioned in the vicinity of the 2nd bending part 5 of the exhaust pipe 1. FIG. In this example, the sleeve tip 101 is disposed on the large-diameter tube portion 6 in the vicinity of the second bent portion 5 as the vicinity of the second bent portion 5, but the sleeve tip 101 is disposed on the second bent portion 5. Or it is also possible to arrange | position on the taper part 4 of the 2nd bending part 5 vicinity.

  A sleeve tip 101 arranged circumferentially on the large-diameter pipe portion 6 in the vicinity of the second bent portion 5 is welded circumferentially to the outer peripheral surface of the exhaust pipe 1, and a circumferential welded portion is attached to the outer peripheral surface of the exhaust pipe 1. 12 is formed. The welded portion 12 of this example is formed from the large-diameter pipe portion 6 near the second bent portion 5 to the second bent portion 5, but the welded portion 12 is changed to the large-diameter pipe portion 6 near the second bent portion 5. It is formed, or it is formed on the second bent part 5, or it is formed on the tapered part 4 near the second bent part 5, or it is formed on the second bent part 5 and the tapered part 4 and the large diameter pipe part 6 in the vicinity thereof. It can be configured.

  Next, a strength comparison test between the exhaust pipe joint structure of the above embodiment and the exhaust pipe joint structure of the comparative example will be described.

  As a premise, in the exhaust pipe joint structure of the comparative example shown in FIG. 3, the large diameter pipe portion 6a of the exhaust pipe 1a is formed longer than the large diameter pipe portion 6 of the above embodiment, and the large diameter pipe portion 6a of the exhaust pipe 1a. The distal end 101a of the sleeve 10a fitted and arranged on the outside of the tube is disposed on the large-diameter pipe portion 6a at a position approximately 9.5 mm away from the second bent portion 5a, and the exhaust pipe 1a of the comparative example The plate thickness is changed to three types of 1.2 mm, 1.5 mm, and 2.0 mm, and other configurations are the same as those in the above embodiment. In the comparative example, components corresponding to those in the above embodiment are indicated by the same reference numerals with a.

  In this strength comparison test, in the exhaust pipe 1 of the example (plate thickness 1.0 mm) and the exhaust pipe 1a of the comparative example (plate thickness 1.2 mm, plate thickness 1.5 mm, plate thickness 2.0 mm) As shown in FIG. 4, the flanges 8 and 8a of the joint flanges 7 and 7a fixed to the exhaust pipes 1 and 1a have a dedicated rigid body that can withstand the load of the strength test and does not affect the strength test result. The fixing jig 20 is fixed by screwing bolts into the bolt holes 9 and the bolt holes on the rigid body fixing jig 20 side, and the ends of the exhaust pipes 1 and 1a opposite to the fixing side of the joint flanges 7 and 7a. The holding part 34 of the fatigue test apparatus 30 was attached to the fatigue test apparatus 30, and the ends of the exhaust pipes 1 and 1a were held by the holding part 34.

  The fatigue test apparatus 30 includes a drive rod 31 that continuously reciprocates in the front-rear direction (A direction in FIG. 4), a mounting portion 32 that is fixed to the tip of the driving rod 31, and one end that rotates to the mounting portion 32. The connecting rod 33 is pivotally supported, and the holding portion 34 of the exhaust pipes 1, 1 a is rotatably supported at the other end of the connecting rod 33. The reciprocating motion is transmitted to the holding portion 34 via the connecting rod 33 pivotally supported at both ends, so that the end of the exhaust pipes 1, 1 a held by the holding portion 34 has an arc direction (direction B in FIG. 4). The load due to the continuous reciprocating motion can be stably and repeatedly applied.

  And several repeated loads applied to the exhaust pipes 1 and 1a with the fatigue test apparatus 30 are set under arbitrary conditions from a low load to a high load, and the fatigue test apparatus 30 is driven for each set constant load, A load was repeatedly applied to the exhaust pipe joint structure such as the exhaust pipes 1 and 1a in the arc direction (direction B in FIG. 4) with the constant load, and the load was repeated until any part of the exhaust pipes 1 and 1a was damaged. Since the exhaust pipe joint structure such as the exhaust pipes 1 and 1a is supported by the rigid body fixing jig 20 at the fixed end, a fixed place such as a part where the joint flanges 7 and 7a and the exhaust pipes 1 and 1a are joined by welding. Stress concentration can be generated in the vicinity of.

  As a result of the strength comparison test, comparison was made by comparing the number of repetitions of the load load until failure in the exhaust pipe joint structure such as the exhaust pipe 1 of the example and the exhaust pipe joint structure such as the exhaust pipe 1a of the comparative example. The strength superiority of the examples was confirmed.

  The damaged part is in the vicinity of the welded portions 12 and 12a of the exhaust pipes 1 and 1a in both the exhaust pipe joint structure of the example and the exhaust pipe joint structure of the comparative example. It can be seen that the strength is weak compared to other parts.

  In addition, FIG. 5 (approximate curve of the test result) shows the number of repetitions of load loading until breakage. In FIG. 5, the vertical axis represents the load to be repeatedly loaded, and the horizontal axis represents the number of load loads to be repeated when the exhaust pipes 1 and 1a are damaged. As can be seen from FIG. 5, the exhaust pipe 1 having a plate thickness of 1.0 mm of the embodiment has a larger number of repetitions that cause damage to repeated loads of the same load than any of the exhaust pipes 1 a of the comparative example. The load required for the same number of repetitions leading to breakage was large, and the strength exceeded the exhaust pipe 1a having the thickest plate thickness of 2.0 mm in the comparative example. That is, the exhaust pipe 1 of the embodiment welded in the vicinity of the second bent portion 5 is different from the exhaust pipe 1a of the comparative example in which the sleeve tip 101a is welded at a position away from the second bent portion 5a. A strength equal to or greater than that of the exhaust pipe 1a can be obtained with a plate thickness that is half that of the exhaust pipe. In other words, when the same strength is obtained, the exhaust pipe 1 may be about half as thick as the exhaust pipe 1a of the comparative example, and it can be seen that a great effect can be achieved in reducing the weight of the exhaust pipe.

  INDUSTRIAL APPLICABILITY The present invention can be used as an exhaust pipe joint structure for welding an exhaust pipe and a joint flange used in, for example, an automobile.

(A) is a front view which shows the exhaust pipe for motor vehicles and a joint flange of an Example, (b) is a partial vertical side view of the same figure (a). The expanded sectional view which shows the welding part of FIG.1 (b), and its periphery. The expanded sectional view which shows the welding part and its periphery in the exhaust pipe for motor vehicles of a comparative example, and a joint flange. Explanatory drawing which shows schematic structure of the strength test system of an exhaust pipe. The graph which shows the result of the intensity | strength test of an Example and a comparative example.

Explanation of symbols

1, 1a Exhaust pipe 2, 2a Small diameter pipe part 3, 3a First bent part 4, 4a Taper part 5, 5a Second bent part 6, 6a Large diameter pipe part 7, 7a Joint flange 8, 8a Flange part 9 Bolt hole 10, 10a Sleeve 101, 101a Sleeve tip 11, 11a Insertion hole 12, 12a Welding part 20 Rigid body fixing jig 30 Fatigue test device 31 Driving rod 32 Mounting part 33 Connecting rod 34 Holding part

Claims (3)

One end of the exhaust pipe is provided with a taper portion that expands toward the end, and a cylindrical large-diameter pipe portion that continues from the taper portion through the bent portion, and the exhaust pipe is inserted into the insertion hole of the joint flange. An exhaust pipe joint characterized by fitting a large-diameter pipe part and placing the end of the insertion hole of the joint flange in the vicinity of a bent part interposed between the tapered part and the large-diameter pipe part and welding to the exhaust pipe Construction. A sleeve is formed on one side of the joint flange, and an end of the insertion hole of the joint flange is a tip of the sleeve, and the tip of the sleeve is disposed in the vicinity of the bent portion and welded to the exhaust pipe. The exhaust pipe joint structure according to claim 1, characterized in that: The exhaust pipe joint structure according to claim 1 or 2, wherein an inclination angle of the tapered portion is set to 20 degrees to 60 degrees.

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