JPH07174270A - Pipe joint structure - Google Patents

Abstract

PURPOSE:To move an inner pipe and an outer pipe relatively and smoothly to compress a seal member easily and secure the relative moving quantity sufficiently while restraining the connected part of both pipes from becoming large-sized. CONSTITUTION:Both axial end parts of a clamp body 12 is bent gently inward. When the clamp body 12 is clamped in the state of being disposed between the engaging piece 5 of an inner pipe 1 and the flange 10 of an outer pipe 6, both axial edges of the clamp body 12 are engaged with the engaging piece 5 and the flange 10, and both pipes 1, 6 are relatively moved in the axial direction of compress a gasket 11 in the axial direction. With further continuation of clamping, the clamp body 12 is going to strength into the flat state, and both edges of the clamp body 12 are going to move in the axial direction. Pressed by both edges of the clamp body 12, the engaging piece 5 and the flange 10 are pushed open in the mutually separating direction, and both pipes 1, 6 are further moved relatively to further compress the gasket 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe joint structure applied to, for example, an exhaust pipe constituting an exhaust system of an internal combustion engine mounted on a vehicle.

[0002]

2. Description of the Related Art Conventionally, as a joint structure of an exhaust pipe constituting an exhaust system of an internal combustion engine, for example, a technique disclosed in Japanese Utility Model Laid-Open No. 2-98292 is known. In this conventional technique, a large diameter portion is formed at one end portion of the inner pipe, and a small diameter portion is integrally formed at one end of the large diameter portion via a step portion. In addition, a large diameter portion is integrally formed at one end of the outer tube via a step portion. Then, in a state where the ring-shaped seal member is externally fitted to the small-diameter portion of the inner pipe, the small-diameter portion and the large-diameter portion of the inner pipe are fitted and inserted into the large-diameter portion of the outer pipe, and the outer peripheral surface of the small-diameter portion of the inner pipe is A seal member is arranged between the large diameter portion of the outer tube and the inner peripheral surface. In this state, the band-shaped clamp body tightens the large-diameter portion of the outer tube in the radial direction, so that the inner tube and the outer tube are connected to each other in a hermetically sealed state via the seal member. ing.

In the exhaust pipe joint structure as described above, in order to more reliably exert the sealing function of the seal member, the seal member is compressed in its axial direction when the outer pipe is tightened by the clamp body. It has been proposed in the past.

That is, for example, as shown in FIG.
On the outer circumference of the large diameter portion 32 of the pair of engaging pieces 3 as engaging portions.
5 is fixed so as to project outward, and the engagement piece 35 thereof is provided obliquely with respect to the plane orthogonal to the axis of the inner pipe 31. A notch 39 corresponding to the engagement piece 35 of the inner pipe 31 is formed at the open end of the large diameter portion 38 of the outer pipe 36. Further, a flange 40 as an engaging portion is formed at the open end of the large diameter portion 38 of the outer pipe 36.
Similarly to the engaging piece 35 of the inner pipe 31, it is also provided obliquely with respect to the surface orthogonal to the axis of the outer pipe 36.

Then, as shown in FIG. 9 (a), the inner tube 3
While fitting the seal member 41 on the small diameter portion 34 of 1,
With the engagement piece 35 of the inner pipe 31 aligned with the notch 39 of the outer pipe 36, the small diameter portion 34 and the large diameter portion 32 of the inner pipe 31 are inserted into the large diameter portion 38 of the outer pipe 36. In this state, the engagement piece 35 of the inner pipe 31 is located in the notch 39 of the outer pipe 36. Further, the sealing member 31 is sandwiched between the step portion 33 of the inner pipe 31 and the step portion 37 of the outer pipe 36. Further, the distance between the engagement piece 35 of the inner pipe 31 and the flange 40 of the outer pipe 36 becomes gradually narrower toward the inside.

Then, in this state, as shown in FIGS.
As shown in FIG. 3, the clamp body 42 is provided between the engaging piece 35 of the inner pipe 31 and the flange 40 of the outer pipe 36 to fix the outer pipe 3 to the outer pipe 3.
The large diameter portion 38 of 6 is tightened in the radial direction. Then, along with the tightening, first, both end edges in the axial direction of the clamp body 42 are engaged with the engaging piece 35 and the flange 40 that are provided obliquely, and the two 35, 40 are separated from each other. Movement power is given. As a result, the inner pipe 31 and the outer pipe 36 are moved relative to each other in the axial direction, and the stepped portion 3 of the inner pipe 31 is moved.
The seal member 41 is axially compressed between the step 3 and the step portion 37 of the outer tube 36. Further, due to this tightening, the outer tube 36 bends inward and the inner tube 31 is tightened. As a result, the outer peripheral surface of the small diameter portion 34 of the inner pipe 31 and the outer pipe 3
The inner peripheral surface of the large-diameter portion 38 of 6 is completely closed by the seal member 41, and the inner tube 31 and the outer tube 36 are connected in a state where airtightness is reliably maintained.

[0007]

However, in the above-mentioned prior art, when the large diameter portion 38 of the outer tube 36 is clamped by the clamp body 42 in the radial direction, both end edges of the clamp body 42 are engaged with the engaging piece 35 and the flange. By engaging with 40, the inner pipe 31 and the outer pipe 36 are relatively moved in the axial direction. Therefore, when tightened by the clamp body 42, an inward force acts on the engagement piece 35 and the flange 40. That is, when the inner pipe 31 and the outer pipe 36 are relatively moved in the axial direction, the inner pipe 31 is clamped by the outer pipe 36 with a strong force, and the sliding resistance between the both 31 and 36 increases. Therefore, the inner tube 31 and the outer tube 36 cannot be smoothly moved relative to each other, and the tightening work becomes difficult and the workability deteriorates. Particularly, in the final stage of tightening by the clamp body 42, the sliding resistance between the inner pipe 31 and the outer pipe 36 becomes the largest, so that an excessive force is required for tightening and the tightening work becomes more difficult. It was a thing.

Further, in order to fully exhibit the sealing function of the seal member 41, it is necessary to sufficiently compress the seal member 41 in the axial direction. That is, it is necessary to secure a sufficient amount of relative movement between the inner pipe 31 and the outer pipe 36 due to the tightening by the clamp body 42. Here, in order to secure a sufficient amount of relative movement between the inner pipe 31 and the outer pipe 36, the inner pipe 3
It is conceivable to make the inclination of the engaging piece 35 of No. 1 and the flange 40 of the outer tube 36 gentle. However, in this way, when the clamp body 42 is tightened, the engagement piece 35
Also, the inward force acting on the flange 40 is further increased. Therefore, the sliding resistance between the inner pipe 31 and the outer pipe 36 is further increased, and a problem arises in that an excessive force is required for tightening.

Further, in order to secure a sufficient amount of relative movement between the inner pipe 31 and the outer pipe 36, it is conceivable that the engagement piece 35 and the flange 40 are largely projected outward. However, in this case, another problem arises in that the connecting portion between the inner pipe 31 and the outer pipe 36 becomes large.

The present invention has been made to solve the above problems, and an object thereof is to smoothly move an inner tube and an outer tube relative to each other in an axial direction by a clamp body so that a sealing member is axially moved. A pipe joint structure that can be easily compressed into a pipe, can secure a sufficient amount of relative movement between the inner pipe and the outer pipe, and does not increase the size of the connecting portion between the inner pipe and the outer pipe. To provide.

[0011]

In order to achieve the above object, in the invention according to claim 1, an inner pipe having an engaging portion at one end, and an engaging portion at the one end and the inner pipe are engaged. When the one end of the inner pipe is inserted into one end of the outer pipe with the outer pipe having a notch corresponding to the portion and the engaging portion of the inner pipe aligned with the notch of the outer pipe, the outer periphery of the inner pipe And the inner circumference of the outer pipe, and the sealing member disposed between the inner pipe and the engaging portion of the two pipes when the inner pipe is inserted into the outer pipe. The outer pipe is tightened in the radial direction to connect the two pipes. A pipe joint structure comprising: a clamp body that fixes the seal member in the axial direction by relatively moving the both tubes in the axial direction by engaging the engaging portions of the both pipes. Is formed to have a substantially convex cross-section so that the intermediate portion in the axial direction bulges outward from both ends in the axial direction. The one in which the features.

Further, in the invention according to claim 2, an inner pipe having an engaging portion at one end, an outer pipe having an engaging portion at one end and a notch corresponding to the engaging portion of the inner pipe, When one end of the inner pipe is inserted into one end of the outer pipe with the engagement portion of the inner pipe aligned with the cutout of the outer pipe, the inner pipe is arranged between the outer periphery of the inner pipe and the inner periphery of the outer pipe. It is placed between the seal member and the engaging part of both pipes when the inner pipe is inserted into the outer pipe, and the outer pipe is tightened in the radial direction to connect and fix both pipes and engage with the engaging parts of both pipes. By doing so, in a pipe joint structure including a clamp body that relatively moves both pipes in the axial direction and compresses the seal member in the axial direction, the clamp body has a wide portion having a wide width in the axial direction. , The width in the axial direction gradually changes between the narrow portion having the narrow width in the axial direction and the wide portion and the narrow portion. It is characterized in that provided the slant portion connecting to.

[0013]

Therefore, according to the first aspect of the invention, first, one end of the inner pipe is inserted into one end of the outer pipe with the engaging portion of the inner pipe being aligned with the notch of the outer pipe. The clamp body is disposed between the engaging portions of the inner pipe and the outer pipe. In the state before tightening, the clamp body is in a state in which the axially intermediate portion is lifted from the outer peripheral surface of the outer tube. When the clamp body is tightened in this state, the clamp body having a substantially convex cross section tends to extend to a flat state due to the tightening. Then, both ends of the clamp body in the axial direction are engaged with the engaging portions of both pipes, and the engaging portions are spread apart in the directions away from each other. As a result, the inner pipe and the outer pipe are relatively moved in the axial direction, and the seal member is compressed in the axial direction.

Here, when the clamp body tries to extend in a flat state due to the tightening by the clamp body, both end edges in the axial direction of the clamp body try to face in the axial direction of both pipes. That is, the inward force generated by tightening the clamp body is dispersed in the axial direction of both pipes. For this reason, the inward force acting on the outer pipe is weakened accordingly, and the inner pipe is not clamped by the outer pipe with a strong force, so that the sliding resistance between the inner pipe and the outer pipe is so large. It never happens. Then, when the clamp body extends to the flat state, the relative movement between the inner pipe and the outer pipe is completed, and in this state, the outer pipe is clamped in the radial direction by the clamp body to connect and fix both pipes. Further, the relative movement amount between the inner pipe and the outer pipe can be increased only by increasing the bulging amount of the axially intermediate portion of the clamp body. in this case,
The sliding resistance between the inner pipe and the outer pipe does not increase, and it is not necessary to increase the protrusion amount of the engaging portions of both pipes.

According to the second aspect of the present invention, before tightening, the clamp body has a narrow width portion corresponding to, for example, the engagement portion of the inner pipe between the engagement portions of the inner pipe and the outer pipe. It is in a state. At this time, the interval between both engaging portions is an interval corresponding to the width of the narrow portion of the clamp body. In this state, when the clamp body is rotated in the circumferential direction around the outer pipe, the wide portion of the clamp body corresponds to the engaging portion of the inner pipe through the slanted portion from the narrow portion along with the rotation. At this time, both ends of the clamp body in the axial direction are engaged with the engaging portions of both pipes, and the wedge action of the oblique portion of the clamp body causes the interval between both engaging portions to correspond to the width of the wide portion of the clamp body. It is gradually spread to the interval you want. As a result, the inner pipe and the outer pipe are relatively moved in the axial direction, and the seal member is compressed in the axial direction. Then, the outer tube is clamped in the radial direction by the clamp body, so that both tubes are connected and fixed.

As described above, since the inner tube and the outer tube are moved relative to each other with the circumferential rotation of the clamp body to compress the seal member, the clamp body is tightened. Sliding resistance hardly acts between the inner pipe and the outer pipe during the relative movement. Further, the relative movement amount between the inner pipe and the outer pipe can be increased only by increasing the difference in width between the narrow portion and the wide portion of the clamp body. In this case, the sliding resistance between the inner pipe and the outer pipe does not increase, and it is not necessary to increase the protrusion amount of the engaging portions of both pipes.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is embodied in a joint structure for an exhaust pipe of an internal combustion engine mounted on a vehicle will be described with reference to FIGS.

As shown in FIGS. 2 to 5, a cylindrical inner pipe 1 is connected to an internal combustion engine (not shown), and a large diameter portion 2 is formed at one end of the inner pipe 1. A small-diameter portion 4 is integrally formed at one end via a tapered step portion 3. The pair of engaging pieces 5 as the engaging portions are the large diameter portion 2
It is welded and fixed to the outer peripheral surface of and protrudes outward. The engagement piece 5 is obliquely provided so as to incline toward the one end side of the inner pipe 1 with respect to a plane orthogonal to the axis of the inner pipe 1. Further, the engaging piece 5 is formed so as to have an arcuate cross section, and its strength is improved. As the engaging portion, a separate engaging piece 5 is used.
Besides the one fixed by welding to the large-diameter portion 2, the large-diameter portion 2 may be formed by partially bulging outward.

The outer tube 6 has a cylindrical shape, and a large diameter portion 8 is integrally formed at one end thereof with a step portion 7 having a tapered shape. A notch 9 corresponding to the engaging piece 5 of the inner pipe 1 is formed at the open end of the large diameter portion 8. The open end of the large-diameter portion 8 is bent outward to form a flange 10 as an engaging portion. The flange 10 is also obliquely provided, like the engaging piece 5 of the inner pipe 1, so as to be inclined toward one end side of the outer pipe 6 with respect to a plane orthogonal to the axis of the outer pipe 6.

The gasket 11 as a ring-shaped seal member is made of expanded graphite and has heat resistance and elasticity to some extent. The gasket 11 has a size that allows it to be fitted onto the small-diameter portion 4 of the inner pipe 1.

The clamp body 12 made of a metallic material has a substantially band shape, and both ends thereof are bent so as to face each other to form a coupling portion 12a. Then, with the bolt 13 inserted between the coupling portions 12a, the nut 14 is screwed onto the bolt 13 and tightened, whereby the clamp body 12 is tightened. The clamp body 12 is formed with a pair of projecting portions 12b projecting outward so as to correspond to the engaging pieces 5 of the inner pipe 1.

As shown in FIGS. 1 and 2, both ends of the clamp body 12 in the axial direction are gently bent inward. That is, the clamp body 12 is formed to have a substantially convex cross section so that the axially intermediate portion thereof bulges outward from both axial end portions.

Next, the operation of the exhaust pipe joint structure constructed as described above will be described. Now, when connecting the inner pipe 1 and the outer pipe 6, as shown in FIG.
While the gasket 11 is fitted onto the small diameter portion 4 of the inner pipe 1 and the engagement piece 5 of the inner pipe 1 is aligned with the cutout 9 of the outer pipe 6, the small diameter portion 4 and the large diameter portion 2 of the inner pipe 1 are Large diameter part 8 of tube 6
To insert. In this state, the engagement piece 5 of the inner pipe 1 is replaced by the outer pipe 6
Located in the notch 9 of the above, the relative rotation of both pipes 1 and 6 is prevented. Also, the gasket 11 is the small diameter portion 4 of the inner pipe 1.
Is disposed between the outer peripheral surface of the inner pipe 1 and the inner peripheral surface of the large-diameter portion 8 of the outer pipe 6, and is sandwiched between the stepped portion 3 of the inner pipe 1 and the stepped portion 7 of the outer pipe 6. . Further, the distance between the engagement piece 5 of the inner pipe 1 and the flange 10 of the outer pipe 6 becomes gradually narrower toward the inside.

Next, as also shown in FIG. 1A, the clamp body 12 is externally inserted from the other end side of the outer pipe 6 so that the engaging piece 5 of the inner pipe 1 and the flange 10 of the outer pipe 6 are joined together. Place in between.
Since the clamp body 12 is formed with a pair of protrusions 12b, the clamp body 12 is flanged to the engagement piece 5 by submerging the engagement piece 5 of the inner pipe 1 at the position of the protrusion 12b. It can be easily arranged between 10 and 10. Further, in this state, the clamp body 12 is rotated in the circumferential direction so that the protruding portion 12b does not correspond to the engaging piece 5.

Then, in this state, when the nut 14 is screwed into the bolt 13 inserted between the connecting portions 12a of the clamp body 12 and tightened, the large diameter portion 8 of the outer tube 6 is radially moved by the clamp body 12. Tightened. Then, with the tightening, as shown in FIGS. 1A and 1B, first, both end edges of the clamp body 12 in the axial direction are engaged with the engaging piece 5 and the flange 10 which are provided in an oblique shape. , 5 and 10 are given a moving force in a direction away from each other. As a result,
The inner pipe 1 and the outer pipe 6 are moved relative to each other in the axial direction, and the gasket 11 is compressed in the axial direction between the step portion 3 of the inner pipe 1 and the step portion 7 of the outer pipe 6.

With tightening, as shown in FIG. 1 (b), both ends of the clamp body 12 in the axial direction come into contact with the outer peripheral surface of the outer tube 6. In this state, the intermediate portion of the clamp body 12 in the axial direction is located. It is in a state of floating from the outer peripheral surface of the outer tube 6. In this state, if you continue tightening,
As shown in (b) and (c), when the clamp body 12 having a substantially convex cross section extends in a flat state, both end edges in the axial direction of the clamp body 12 are directed toward the axial direction of the inner pipe 1 and the outer pipe 6. To do. Then, the both ends of the clamp body 12 in the axial direction are pressed, and the engaging piece 5 and the flange 10 are spread apart in the direction in which they are separated from each other. As a result, the inner pipe 1 and the outer pipe 6 are further moved in the axial direction, and the gasket 11 is further compressed in the axial direction. The thickness of the clamp body 12 is set to an appropriate value so that it can be extended to a flat state as it is tightened.

Here, as described above, the clamp body 12
Along with the tightening by, the both ends in the axial direction of the clamp body 12 try to move toward the axial direction of the pipes 1 and 6. That is, the inward force generated by the tightening of the clamp body 12 is dispersed in the axial direction of the tubes 1 and 6. Therefore, the inward force acting on the outer pipe 6 is weakened accordingly, and the inner pipe 1 is not clamped by the outer pipe 6 with a strong force, so that the sliding force between the inner pipe 1 and the outer pipe 6 is reduced. The dynamic resistance does not increase so much. Therefore, the inner tube 1 and the outer tube 6 can be smoothly moved relative to each other with the tightening by the clamp body 12, and the gasket 11 can be easily compressed in the axial direction.

Then, as shown in FIG. 1 (c), when the clamp body 12 is completely extended to the flat state, the relative movement between the inner pipe 1 and the outer pipe 6 is completed, that is, the compression of the gasket 11 is completed. Will be terminated. Then, in this state, the clamp body 12
Thus, the large diameter portion 8 of the outer pipe 6 is tightened in the radial direction, and the inner pipe 1 and the outer pipe 6 are connected and fixed. As a result, the outer peripheral surface of the small diameter portion 4 of the inner pipe 1 and the inner peripheral surface of the large diameter portion 8 of the outer pipe 6 are completely closed by the gasket 11 in the axially compressed state, 1 and the outer tube 6 are connected in a state where airtightness is reliably maintained.

As described above, in this embodiment, the clamp body 12 is formed to have a substantially convex cross section so that the axially intermediate portion thereof bulges outward from both axial end portions thereof. Then, in the final stage of tightening by the clamp body 12, the inner tube 1 and the outer tube 6 are further moved relative to each other by utilizing the fact that the clamp body 12 tries to extend to a flat state, and the gasket 11 is further moved. I try to compress it.

That is, since the tightening force is still weak in the initial stage of tightening by the clamp body 12,
Even if the inner pipe 1 and the outer pipe 6 are moved relative to each other by the same means as in the conventional technique, the sliding resistance between the inner pipe 1 and the outer pipe 6 does not increase so much, and Can be smoothly moved relative to each other. However, in the final stage of tightening, the compression reaction force of the gasket 11 may become large, and thus a large force is required for tightening. Therefore, with the tightening, the inward force acting on the outer pipe 6 also increases, and the sliding resistance increases.

However, when the inner tube 1 and the outer tube 6 are moved relative to each other by utilizing the fact that the clamp body 12 tries to extend in a flat state as in the present embodiment, the clamp body 1 is moved.
The inward force generated by tightening 2 is dispersed in the axial direction of both tubes 1, 6. Therefore, even in the final stage of tightening, the inward force acting on the outer pipe 6 does not become so large, and the sliding resistance between the inner pipe 1 and the outer pipe 6 increases so much. There is no. Therefore,
It is possible to easily perform the tightening work and improve workability without requiring an excessive force for tightening.

Further, in this embodiment, in the initial stage of tightening, after the inner tube 1 and the outer tube 6 are relatively moved by the same means as in the prior art, the clamp body 12 is intended to extend to a flat state. By utilizing this, the inner tube 1 and the outer tube 6 are further moved relative to each other. Therefore, the amount of relative movement between the inner pipe 1 and the outer pipe 6 can be increased, and the gasket 11 can be sufficiently compressed in the axial direction. As a result, the gasket 11 can have a sufficient sealing function. Can be demonstrated. In this case, unlike the prior art, it is not necessary to make the inclination of the engagement piece 5 and the flange 10 gentle or to increase the amount of protrusion thereof, so that the sliding between the inner pipe 1 and the outer pipe 6 is not required. Dynamic resistance increases,
There is no fear that the connecting portion between the inner pipe 1 and the outer pipe 6 becomes large.

Further, in this embodiment, the clamp body 1 is simply used.
Since 2 has a simple structure in which the axially intermediate portion bulges outward from both axial end portions, the manufacturing thereof does not become complicated.

[0034]

[Second Embodiment] Next, a second embodiment of the present invention will be described.
This will be described with reference to FIGS. 6 and 7. Now, FIGS. 6 and 7
As shown in FIG. 2, in the second embodiment, unlike the first embodiment, the clamp body 16 is formed in a flat plate cross section. At the position corresponding to the pair of protrusions 16b of the clamp body 16, one end edge of the clamp body 16 in the axial direction is cut out, and the width in the axial direction is narrowed. Hereinafter, the portion of the clamp body 16 having a narrow width in the axial direction will be referred to as a narrow portion 17, and the portion other than the narrow portion 17 having a wide width in the axial direction will be referred to as a wide portion 18. In addition, the narrow portion 17 and the wide portion 18
Between and, there is a slanted portion 19 that connects the two portions 17 and 18 so that the width in the axial direction gradually changes.

Further, in the second embodiment, unlike the first embodiment, the engaging piece 5 of the inner pipe 1 and the flange 1 of the outer pipe 6 are provided.
0 is raised in a direction orthogonal to the axis of each of the tubes 1 and 6.

Now, in the exhaust pipe joint structure constructed as described above, when the inner pipe 1 and the outer pipe 6 are connected, as shown in FIG. 7A, first, the first embodiment is used. Similarly to the above case, the small diameter portion 4 and the large diameter portion 2 of the inner pipe 1 are inserted into the large diameter portion 8 of the outer pipe 6. Next, the clamp body 16 is externally inserted from the other end side of the outer pipe 6, and the protrusion 16b thereof is aligned with the engagement piece 5 of the inner pipe 1, and the engagement piece 5 and the flange 10 of the outer pipe 6 are aligned. Place it between and. In this state, the gap between the engagement piece 5 and the flange 10 corresponds to the width of the narrow portion 17 of the clamp body 16.

In this state before tightening, the clamp body 16
7 is rotated in the circumferential direction around the outer pipe 6, the rotation causes the wide portion 18 from the narrow portion 17 of the clamp body 16 to the inner portion via the slant portion 19 as shown in FIG. 7B. Tube 1
It corresponds to the engaging piece 5 of. At this time, both ends of the clamp body 16 in the axial direction are engaged with the engagement piece 5 and the flange 10,
The wedge action of the slanted portion 19 of the clamp body 16 gradually widens the gap between the engagement piece 5 and the flange 10 to a gap corresponding to the width of the wide portion 18 of the clamp body 16. As a result, the inner pipe 1 and the outer pipe 6 are relatively moved in the axial direction, and the gasket 11 is compressed in the axial direction.

After that, when the nut 14 is screwed into the bolt 13 inserted between the joint portions 16a of the clamp body 16 and tightened, the large diameter portion 8 of the outer tube 6 is tightened in the radial direction by the clamp body 16, The inner pipe 1 and the outer pipe 6 are connected and fixed. As a result, the outer peripheral surface of the small diameter portion 4 of the inner pipe 1 and the inner peripheral surface of the large diameter portion 8 of the outer pipe 6 are completely closed by the gasket 11 in the axially compressed state, 1 and the outer tube 6 are connected in a state where airtightness is reliably maintained.

As described above, in the second embodiment, the clamp body 16 has the narrow width portion 17, the wide width portion 18, and the widths of the narrow width portion 17 and the wide width portion 18 gradually change. The slanted portion 19 is provided for connection. Then, as the clamp body 16 rotates in the circumferential direction, the wedge action of the slanted portion 19 of the clamp body 16 causes the inner pipe 1 and the outer pipe 6 to relatively move to compress the gasket 11. There is. Then, after the gasket 11 is thus compressed, the outer tube 6 is tightened by the clamp body 16.

Therefore, when the inner pipe 1 and the outer pipe 6 are moved relative to each other, the inner pipe 1 is not clamped by the outer pipe 6, so that the inner pipe 1 and the outer pipe 6 are not moved during the relative movement. Sliding resistance hardly works. In addition, the clamp body 1
By the wedge action of the slanted portion 19 of 6, the engaging piece 5 and the flange 10 can be smoothly spread with a small force. Therefore, also in the second embodiment, as in the first embodiment, the inner pipe 1 and the outer pipe 6 can be smoothly moved relative to each other to easily compress the gasket 11 in the axial direction. It is possible to easily perform the tightening work and improve workability.

Further, in the second embodiment, the clamp body 16
The relative movement amount between the inner pipe 1 and the outer pipe 6 can be increased only by increasing the width difference α between the narrow portion 17 and the wide portion 18. Therefore, as in the first embodiment, the gasket 11 can be sufficiently compressed in the axial direction, and the sealing function of the gasket 11 can be sufficiently exerted. In this case, unlike the prior art, it is not necessary to make the inclination of the engagement piece 5 and the flange 10 gentle or to increase the amount of protrusion thereof, so that the sliding between the inner pipe 1 and the outer pipe 6 is not required. As in the first embodiment, there is no fear that the dynamic resistance will increase or the connecting portion between the inner pipe 1 and the outer pipe 6 will become large.

Further, in the second embodiment, the clamp body 1
Since it has a simple configuration in which the width of 6 in the axial direction is only partially changed, its production is not complicated. The present invention is not limited to the above-described embodiments, and the configurations of the respective parts may be modified and embodied as follows, for example, without departing from the spirit of the present invention.

(1) In the first embodiment, as shown in FIG. 8A, the clamp body 12 is formed in a substantially arcuate cross section, or as shown in FIG. 8B, the clamp body 12 is formed. Bending at the middle part in the axial direction to form a substantially V-shaped cross section. That is, the clamp body 12 may have any shape as long as the axially intermediate portion of the clamp body 12 bulges outward from both axial end portions thereof.

(2) In the first and second embodiments, the bulge amount of the axially intermediate portion of the clamp body 12 and the clamp body 1
The difference α between the widths of the narrow portion 17 and the wide portion 18 of 6 should be changed appropriately. Thereby, the relative movement amount of the inner pipe 1 and the outer pipe 6 can be easily adjusted to a required amount.

(3) In the first embodiment, as in the second embodiment, the engaging piece 5 of the inner pipe 1 and the flange 10 of the outer pipe 6 are provided.
Up in the direction orthogonal to the axis of each tube 1, 6. The relative movement between the inner pipe 1 and the outer pipe 6 is controlled by the clamp body 12
The clamp body 12 should only be stretched to a flat state when tightened by. In this case, in order to make the relative movement amount between the inner pipe 1 and the outer pipe 6 sufficient, the bulge amount of the axially intermediate portion of the clamp body 12 may be increased. At this time, of course, the sliding resistance between the inner pipe 1 and the outer pipe 6 does not increase, and the connecting portion of both pipes 1 and 6 does not increase in size.

(4) Clamp body 16 in the second embodiment
To have a shape in which the axially intermediate portion bulges outward from both axial end portions. That is, the shape of the clamp body 12 of the first embodiment is applied to the clamp body 16 of the second embodiment.

(5) The pipe joint structure of the present invention should be embodied in various pipe joint structures other than the exhaust pipe joint structure of the internal combustion engine. For example, when heat resistance does not need to be taken into consideration so much, the inner tube and the outer tube may be formed of a synthetic resin material. Further, in this case, the clamp body may be formed of a synthetic resin material, or rubber may be used as the seal member.

[0048]

As described in detail above, according to the present invention, the inner tube and the outer tube can be smoothly moved relative to each other in the axial direction by the clamp body, and the seal member can be easily compressed in the axial direction. Moreover, it is possible to secure a sufficient amount of relative movement between the inner pipe and the outer pipe, and it is possible to exert an excellent effect that the connecting portion between the inner pipe and the outer pipe is not increased in size.

[Brief description of drawings]

FIG. 1 shows a first embodiment in which the present invention is embodied in a joint structure for an exhaust pipe of an internal combustion engine, and (a) shows a state in which a clamp body is arranged between an engaging piece and a flange. A sectional view, (b) is a sectional view showing an intermediate stage of tightening by a clamp body, and (c) is a sectional view showing a state where the clamp body has been extended to a flat state by tightening.

FIG. 2 is an exploded perspective view showing an entire joint structure of an exhaust pipe.

FIG. 3 is a front view showing a state in which tightening by a clamp body is completed in the exhaust pipe joint structure.

FIG. 4 is a cross-sectional view of the joint structure of the exhaust pipe of FIG.

5 is a cross-sectional view taken along the line AA of FIG.

FIG. 6 is a perspective view showing a clamp body in an exhaust pipe joint structure according to a second embodiment.

7A and 7B show an exhaust pipe joint structure of the second embodiment, wherein FIG. 7A is a front view showing a state in which a clamp body is arranged between an engaging piece and a flange, and FIG. 7B is a clamp. It is a front view which shows the state which rotated the body in the circumferential direction.

FIG. 8 is a sectional view of an essential part showing another example of the clamp body in the first embodiment.

9A and 9B are views showing a joint structure of an exhaust pipe in the related art, in which FIG. 9A is a sectional view showing a state in which a clamp body is arranged between an engaging piece and a flange, and FIG. It is sectional drawing which shows the state which performed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Inner pipe, 5 ... Engaging piece as an engaging part, 6 ... Outer pipe, 9 ...
Notch, 10 ... Flange as engaging portion, 11 ... Gasket as sealing member, 12 ... Clamping body, 16 ...
Clamp body, 17 ... Narrow portion, 18 ... Wide portion, 19 ... Oblique portion.

Claims (2)

[Claims] 1. An inner tube having an engaging portion at one end, an outer tube having an engaging portion at one end and a notch corresponding to the engaging portion of the inner tube, and an engaging portion of the inner tube at the outer portion. When one end of the inner pipe is inserted into one end of the outer pipe in a state where it is aligned with the cutout of the pipe, a seal member arranged between the outer periphery of the inner pipe and the inner periphery of the outer pipe, and the inner pipe It is placed between the engaging parts of both pipes when inserted into, and both pipes are connected and fixed by tightening the outer pipe in the radial direction, and by engaging the engaging parts of both pipes, In a pipe joint structure including a clamp body that relatively moves to, and a clamp body that compresses the seal member in the axial direction, so that the intermediate body in the axial direction bulges outward from both end portions in the axial direction, A pipe joint structure characterized by having a substantially convex cross section. 2. An inner pipe having an engaging portion at one end, an outer pipe having an engaging portion and a notch corresponding to the engaging portion of the inner pipe at one end, and the engaging portion of the inner pipe being the outer portion. When one end of the inner pipe is inserted into one end of the outer pipe in a state where it is aligned with the cutout of the pipe, a seal member arranged between the outer periphery of the inner pipe and the inner periphery of the outer pipe, and the inner pipe It is placed between the engaging parts of both pipes when inserted into, and both pipes are connected and fixed by tightening the outer pipe in the radial direction, and by engaging the engaging parts of both pipes, In the pipe joint structure including a clamp body that relatively moves the seal member in the axial direction by relatively moving the seal member in the axial direction, the clamp body includes a wide portion having a wide width in the axial direction and a narrow width having a narrow width in the axial direction. And a slanted portion that connects the wide portion and the narrow portion so that the width in the axial direction gradually changes. Pipe joint structure, characterized in that digit.