JP2009197714A - Pipe connecting structure and pipe connecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pipe connection structure capable of preventing the loosening of the caulking caused by twist in the rotational direction, and being connected by a small device. <P>SOLUTION: Exhaust pipes 1, 2 to be connected have circular sectional shapes, and one exhaust pipe 2 is inserted in an expanded portion 4 of the other exhaust pipe 1. An overlapping portion of the expansion part 4 of the exhaust pipe 1 and the other exhaust pipe 2 is deformed inwardly in the radial direction from a circular section to a non-circular section at two or more parts, and caulked. The two non-circular sectional shapes are different in the circumferential direction. During this time, the sectional shape is deformed at two parts from the circular shape to the same hexagonal shape at two parts, and the phase in the circumferential direction to calk the pipes while deviating the phase in the circumferential direction, and the sectional shapes at two parts are different in the circumferential direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pipe connection structure and a pipe connection method for connecting pipes such as exhaust pipes provided in an exhaust system of an internal combustion engine.

  Conventionally, when connecting pipes and pipes, for example, in an exhaust system of an internal combustion engine, an exhaust manifold, a converter, and a silencer are disposed along the direction of exhaust flow, and an exhaust pipe and a connecting pipe of the converter, Alternatively, the exhaust pipe and the connection pipe of the silencer are connected by welding.

  However, in connection by welding, stress tends to concentrate on the welded part, and in order to give sufficient strength, a sufficient thickness is required for the thickness of the exhaust pipe etc., which has been a problem in weight reduction. . Further, in order to prevent leakage of fluid flowing inside the pipe, for example, leakage of exhaust gas, the entire circumference of the pipe has to be welded, resulting in a problem that it takes time for processing. Furthermore, corrosion is likely to proceed preferentially at and near the welding location, and gas is generated during the welding operation, which is undesirable in the working environment.

Therefore, as disclosed in Patent Document 1, a method of connecting by press-fitting instead of welding has also been proposed. For example, the exhaust pipe is press-fitted into a connection pipe provided integrally with the end plate of the silencer. In that case, while clamping the outer periphery of the main-body cylinder part of a silencer, the outer periphery of an exhaust pipe is clamped and press-fit, and pipes are connected.
JP 2005-194996 A

  However, in the case of connecting pipes by such conventional press fitting, even if an external force is applied in the axial direction of the pipe, the pipes connected by press fitting are firmly prevented from being pulled out, but the cross section of the pipe is circular. Therefore, when a rotational force acting in the circumferential direction that twists the pipes acts, the press-fitting location slips in the circumferential direction and the caulking is loosened, and exhaust may leak or the press-fitting location may be easily pulled out. was there.

  In addition, in the exhaust system of an internal combustion engine, it is necessary to clamp and press fit the outer periphery of a large object such as a converter or a silencer, which increases the size of the device and requires a large working force for the pressing force during press fitting. Also from this point, there is a problem that the apparatus is enlarged.

  An object of the present invention is to provide a pipe connection structure and a pipe connection method that prevent loosening due to twisting in the rotational direction and can be connected by a small device.

In order to achieve this problem, the present invention has taken the following measures in order to solve the problem. That is,
In the pipe connection structure that connects the pipes,
Both the tubes have a circular cross-sectional shape, and the other tube is inserted into one of the tubes,
The overlapping portion of the pipe and the pipe is radially inward, the cross-sectional shape is changed from a circular shape to a non-circular shape at two or more locations, and the two non-circular cross-sectional shapes are different in the circumferential direction. This is a pipe connection structure characterized by this.

  In that case, the said pipe | tube may be an exhaust pipe provided in the exhaust system of an internal combustion engine. In addition, the cross-sectional shape is deformed from a circular shape to the same polygonal non-circular shape at two locations, and the phases are shifted in the circumferential direction, and the cross-sectional shapes at the two locations are varied in the circumferential direction. But you can. Alternatively, the cross-sectional shape is deformed at two locations into a non-circular shape having a protrusion protruding radially from the circular shape, and the phases are shifted in the circumferential direction to cause the cross-sectional shapes at the two locations in the circumferential direction. Different configurations may be used.

In the pipe connection method for connecting pipes to each other,
The two tubes have a circular cross-sectional shape, and the other tube is inserted into one of the tubes,
With the molded member, the overlapping portion between the tube and the tube is radially inward, the cross-sectional shape is deformed from a circular shape to a non-circular shape at two or more locations, and the two non-circular cross-sectional shapes are It is a pipe connection method characterized in that it is caulked with different circumferential directions.

  In the pipe connection structure of the present invention, the cross-sectional shape is deformed from a circular shape to a non-circular shape at two or more locations, and the two non-circular cross-sectional shapes are different in the circumferential direction. This prevents the caulking from being loosened and can be connected with a small device. In addition, according to the pipe connection method of the present invention, the cross-sectional shape is deformed from a circular shape to a non-circular shape at two or more locations, and the two non-circular cross-sectional shapes are different in the circumferential direction. This prevents the loosening of the caulking due to the twisting of the cable and can be connected with a small device.

The best mode for carrying out the present invention will be described below in detail with reference to the drawings.
In this embodiment, it is used for an exhaust system of an internal combustion engine. As shown in FIGS. 1 and 2, reference numerals 1 and 2 are exhaust pipes, and both exhaust pipes 1 and 2 have a circular cross section. The other exhaust pipe 2 is inserted into and connected to one exhaust pipe 1. In addition, an enlarged diameter portion 4 is formed at one end of one exhaust pipe 1 so that the other exhaust pipe 2 can be inserted in advance.

  The outer periphery of the other exhaust pipe 2 is inserted into the inner periphery of the enlarged diameter part 4, and the overlapping part between the enlarged diameter part 4 of one exhaust pipe 1 and the other exhaust pipe 2 is caulked in the radial direction and connected. Yes. The insertion does not need to be press-fitted, and it is sufficient that the inner diameter of the enlarged diameter portion 4 and the outer diameter of the other exhaust pipe 2 are formed to such an extent that caulking can be performed at overlapping portions.

  Caulking is performed at two locations at a predetermined interval at an overlapping portion between the enlarged diameter portion 4 of one exhaust pipe 1 and the other exhaust pipe 2. Further, the caulking is performed by deforming the exhaust pipes 1 and 2 toward the inner side in the radial direction.

  In this embodiment, as shown in FIGS. 3 and 4, the cross-sectional shape is formed into a hexagonal shape by two pairs of forming members 6 and 8, and caulking is performed. The two pairs of molded members 6 and 8 are configured by six divided molds. By moving the divided molds toward the axial center of both exhaust pipes 1 and 2, both exhaust pipes 1 and 2 are formed. , 2 is deformed toward the inside in the radial direction, and the cross-sectional shape is formed into a hexagonal shape. At this time, caulking is performed without inserting a mold or the like on the inner peripheral side of the other exhaust pipe 2.

  Caulking is performed by two pairs of forming members 6 and 8 at two places, ie, a first caulking place 11 and a second caulking place 12 that are overlapping portions. As shown in FIG. 3, the first caulking portion 11 on the distal end side of the enlarged diameter portion 4 is deformed toward the inside in the radial direction of both the exhaust pipes 1 and 2 by the forming member 6 and the cross-sectional shape is formed into a hexagonal shape. To do. Thereby, the inner periphery of the enlarged diameter portion 4 of one exhaust pipe 1 is in close contact with the outer periphery of the other exhaust pipe 2 and caulked.

  Moreover, in the 2nd crimping location 12, as shown in FIG. 4, it deform | transforms toward the radial direction inner side of both the exhaust pipes 1 and 2 by the shaping | molding member 8, and shape | molds a cross-sectional shape in hexagonal shape. Thereby, the inner periphery of the enlarged diameter portion 4 of one exhaust pipe 1 is in close contact with the outer periphery of the other exhaust pipe 2 and caulked.

  In the present embodiment, the first caulking location 11 and the second caulking location 12 are caulked at a predetermined interval, and the present embodiment is provided between the first caulking location 11 and the second caulking location 12. Then, it is crimped so that the convex part 14 may remain.

  The convex portion 14 may remain as an unmolded portion during caulking by the two molded members 6 and 8, or the first caulking location 11 and the second caulking location 12 have a smaller deformation amount and are radial. You may make it remain as a shaping | molding part protruded outside. The convex portion 14 may be left as needed. As shown in FIGS. 7 and 8, the first caulking portion 11 and the second caulking portion 12 are continuous without being spaced apart. It may be molded. At this time, the molded members 6 and 8 may be formed integrally.

  The first caulking location 11 and the second caulking location 12 are formed by deforming the exhaust pipes 1 and 2 having a circular cross-sectional shape into a hexagonal shape having a non-circular cross-sectional shape. Moreover, the first caulking location 11 and the second caulking location 12 are formed by shifting the two non-circular cross-sectional shapes in the circumferential direction.

  In the present embodiment, since it is deformed into a regular hexagonal shape, the first caulking location 11 and the second caulking location 12 are formed by shifting the phase to a state rotated in the circumferential direction by 30 degrees. The phase shift is not limited to 30 degrees and may be 10 degrees. When a force for pulling out the other exhaust pipe 2 from the enlarged diameter portion 4 of one exhaust pipe 1 is applied, What is necessary is just to shape | mold so that it may become resistance with respect to drawing force by the shift | offset | difference of the phase of a cross-sectional shape with the crimping location 12. FIG.

  Moreover, in this embodiment, although the 1st crimping location 11 and the 2nd crimping location 12 were shape | molded in the hexagon shape, you may shape | mold not only to this but polygonal shapes, such as an octagon shape and a decagonal shape. Further, the first caulking location 11 may be formed in a hexagonal shape, the second caulking location 12 may be formed in an octagonal shape, and the first caulking location 11 and the second caulking location 12 are formed in a non-circular shape, You may shape | mold so that the cross-sectional shape may differ.

  If the first caulking location 11 and the second caulking location 12 have the same cross-sectional shape, the same material can be used for the two pairs of molded members 6 and 8. Or you may shape | mold the 1st crimping location 11 and the 2nd crimping location 12 by shifting a phase with the pair of shaping | molding members 6. FIG.

Next, the effect | action of the pipe connection structure of this embodiment is demonstrated.
The exhaust gas flowing into the other exhaust pipe 2 flows out from the other exhaust pipe 2 to the one exhaust pipe 1. At that time, the exhaust passes through the first caulking location 11 and the second caulking location 12 and flows out into one exhaust pipe 1.

  At that time, the first caulking location 11 and the second caulking location 12 prevent exhaust from leaking between the inner circumference of the enlarged diameter portion 4 and the outer circumference of the other exhaust pipe 2. Further, the convex portion 14 between the first caulking location 11 and the second caulking location 12 can further prevent the exhaust gas from leaking.

  On the other hand, when an external force acts on one exhaust pipe 1 and the other exhaust pipe 2, for example, when a force pulling out the other exhaust pipe 2 from one exhaust pipe 1 acts, Since the phase of the cross-sectional shape with respect to the caulking location 12 is shifted and the cross-sectional shape is different, it is prevented from being pulled out. Further, the protrusion 14 between the first caulking portion 11 and the second caulking portion 12 can further prevent the pulling out.

  Alternatively, when a force that twists one exhaust pipe 1 and the other exhaust pipe 2 in the circumferential direction is applied, the first caulking location 11 and the second caulking location 12 have non-circular cross-sectional shapes. This prevents slippage between the inner circumference of the enlarged diameter portion 4 and the outer circumference of the other exhaust pipe 2. As described above, the first caulking location 11 and the second caulking location 12 can maintain the airtightness of the exhaust gas, and can prevent pulling out and twisting by an external force.

  As described above, in the present embodiment, the other exhaust pipe 2 is inserted into the enlarged diameter portion 4 of the exhaust pipe 1 and the overlapping portion between the enlarged diameter portion 4 and the exhaust pipe 2 is deformed and crimped radially inward. Yes. Since they are connected by caulking that is deformed radially inward, caulking does not require a large device. In addition, since a large acting force is not required, a large device that generates a large acting force is not required.

  Next, a second embodiment having a different cross-sectional shape with respect to the first caulking location 11 and the second caulking location 12 will be described with reference to FIGS. As shown in FIG. 5, in the first caulking location 21 of the second embodiment, a plurality of protrusions 24 protruding in the radial direction are formed at overlapping locations of the enlarged diameter portion 4 and the exhaust pipe 2. The first caulking portion 21 is formed by a pair of forming members 26, and the pair of forming members 26 is divided into four according to the positions of the four protrusions 24, and the protrusions 24 are provided between the divided forming members 26. Is formed. A pair of molding members 26 are pressed against the outer periphery of the enlarged diameter portion 4 of one exhaust pipe 1 to deform and crimp the enlarged diameter portion 4 and the other exhaust pipe 2 radially inward. The protrusion 24 is formed simultaneously with the caulking.

  As shown in FIG. 6, the second caulking portion 22 is formed with a plurality of protrusions 28 protruding in the radial direction at overlapping portions of the enlarged diameter portion 4 and the exhaust pipe 2. The second caulking portion 22 is formed by a pair of forming members 30, and the pair of forming members 30 is divided into four according to the positions of the four protrusions 28, and the protrusions 28 are provided between the divided forming members 30. Is formed. The pair of molding members 30 are pressed against the outer periphery of the enlarged diameter portion 4 of one exhaust pipe 1 to deform and crimp the enlarged diameter portion 4 and the other exhaust pipe 2 radially inward. At the same time as the caulking, the projection 28 is formed.

  The four projections 24 at the first caulking location 21 and the four projections 28 at the second caulking location 21 are formed with a phase shift of 45 degrees, and as shown in FIGS. 5 and 6, by shifting the phase, The cross-sectional shapes are formed so as to be different from each other. In addition, you may make it provide the convex part 14 mentioned above between the 1st crimping location 21 and the 2nd crimping location 22. FIG.

  Even in the case of the second embodiment, when a force for pulling out the other exhaust pipe 2 from one exhaust pipe 1 is applied, the cross-sectional shape of the projection 24 of the first caulking location 21 and the projection 28 of the second caulking location 22 is increased. Since the phase is shifted and the cross-sectional shape is different, it is prevented from being pulled out.

  Further, when a force that twists one exhaust pipe 1 and the other exhaust pipe 2 in the circumferential direction is applied, the first caulking location 21 and the second caulking location 22 are non-cross-sectional in shape due to both projections 24 and 28. Since it has a circular shape, slipping between the inner periphery of the enlarged diameter portion 4 and the outer periphery of the other exhaust pipe 2 is prevented by twisting. In this manner, the first caulking location 21 and the second caulking location 22 can keep the airtightness of the exhaust gas and can prevent pulling out and twisting due to external force.

  Thus, in the second embodiment as well, since the connection is performed by caulking that is deformed radially inward, a caulking process does not require a large apparatus. In addition, since a large acting force is not required, a large device that generates a large acting force is not required.

  Further, as shown in FIG. 9, in the exhaust system of the internal combustion engine 51, the exhaust manifold 52, the converter 54, the silencers 56, 58, and the like are connected by the exhaust pipes 1, 2, so that the length along the exhaust flow is long. When connected by press-fitting, it is difficult to obtain the overall shape after press-fitting. For example, when the converter 54 and the exhaust pipe 60 are press-fitted, the overall length of the exhaust system along the flow of the exhaust is long, so that the deviation of the angle after press-fitting becomes a large dimensional error in the silencer 58 on the downstream side. Appear. Under the influence of the shape after the press-fitting, it is difficult to obtain the accuracy of the entire shape after the press-fitting.

  Since both the above-described embodiments can be caulked by the molding members 6, 8, 26, and 30 from the outer peripheral side, the axial length of the exhaust pipes 1 and 2 is long, and even if the silencer has a large outer shape, It can be easily connected without requiring a large device. Furthermore, in the state where the other exhaust pipe 2 (or one exhaust pipe 1) is inserted into the exhaust pipe 1 (or the exhaust pipe 2) integral with the converter or the silencer, the accuracy of the overall shape and dimension is ensured. The dimensional accuracy of the entire shape can be easily secured by caulking with the forming members 6, 8, 26, 30 from the outer periphery side after being fixed and supported on a jig or the like. Moreover, since it can be connected even in a narrow space, the exhaust system can be connected to the side of the assembly line of the vehicle, and after being transported to the side of the assembly line in the state of individual parts, the exhaust system is assembled to the side of the assembly line. Can also be easily done.

  The present invention is not limited to such embodiments as described above, and can be implemented in various modes without departing from the gist of the present invention.

It is a front view of the pipe connection structure as one embodiment of the present invention. It is sectional drawing along the axial direction of the pipe connection structure of this embodiment. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is sectional drawing orthogonal to the axial direction of the 1st crimping location of the pipe connection structure of 2nd Embodiment. It is sectional drawing orthogonal to the axial direction of the 2nd crimping location of the pipe connection structure of 2nd Embodiment. It is a front view of the pipe connection structure as another embodiment. It is sectional drawing along the axial direction of the pipe connection structure as another this embodiment. It is explanatory drawing which shows the exhaust system of an internal combustion engine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Exhaust pipe 4 ... Diameter expansion part 6, 8, 26, 30 ... Molding member 11, 21 ... 1st crimping place 12, 22 ... 2nd crimping place 14 ... Convex part 24, 28 ... Protrusion

Claims (5)

In the pipe connection structure that connects the pipes,
Both the tubes have a circular cross-sectional shape, and the other tube is inserted into one of the tubes,
The overlapping portion of the pipe and the pipe is radially inward, the cross-sectional shape is changed from a circular shape to a non-circular shape at two or more locations, and the two non-circular cross-sectional shapes are different in the circumferential direction. A pipe connection structure characterized by that. The pipe connection structure according to claim 1, wherein the pipe is an exhaust pipe provided in an exhaust system of an internal combustion engine. The cross-sectional shape is deformed from a circular shape to a non-circular shape of the same polygonal shape at two locations, and the phases are shifted in the circumferential direction and the cross-sectional shapes at the two locations are varied in the circumferential direction. The pipe connection structure according to claim 1 or 2. The cross-sectional shape is deformed in two places into a non-circular shape having protrusions protruding radially from the circular shape, and the phases are shifted in the circumferential direction to cause the cross-sectional shapes to differ in the circumferential direction. The pipe connection structure according to claim 1 or 2, wherein the pipe connection structure is provided. In a pipe connection method for connecting pipes to each other,
The two tubes have a circular cross-sectional shape, and the other tube is inserted into one of the tubes,
With the molded member, the overlapping portion between the tube and the tube is radially inward, the cross-sectional shape is deformed from a circular shape to a non-circular shape at two or more locations, and the two non-circular cross-sectional shapes are A pipe connection method characterized by caulking in different circumferential directions.

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