Joint structure for propulsion pipe

Abstract

To provide a joint structure for a propulsion pipe that can suppress damage to a packing for sealing between two connected propulsion pipes during connection of the packing.SOLUTION: In a portion side of a packing 20 where a fixing projection 12B is provided on an outer surface, a fixing groove 20A which is recessed on the outer surface side is formed. When the packing 20 is installed, the fixing projection 12B has been fitted with play to the fixing groove 20A. On an inner surface side of the packing 20, inner ribs 21A-21D locally projecting inward are formed in this order from the right side. The inside of the fixing groove 20A and a space on an inner surface side of the packing 20 communicate with each other via an air hole 20B between the inner rib 21C and the inner rib 21D. The fixing groove 20A is provided between the inner rib 21C and the inner rib 21D, and is not provided in a portion where the inner ribs 21A-21D are provided in a horizontal direction in the figure.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a joint structure for a jacking pipe used when connecting jacking pipes made of Hume pipes or the like. [Background technology]

[0002] Cylindrical Hume pipes (jacking pipes) made of reinforced concrete or the like are used by being installed underground, etc., with a large number of pipes connected in the central axial direction. For this reason, a structure (joint structure) is provided at the end of the jacking pipe to enable this connection to be made easily and reliably.

[0003] Such a joint structure is required to be able to seal the interior through which water or the like flows, and Patent Document 1, for example, describes such a structure. In this structure, an annular metal collar is provided at the end of one of the propulsion pipes to be connected so as to protrude beyond the propulsion pipe in the central axial direction, and the end of the other propulsion pipe to be connected serves as a tip joint portion whose outer diameter is locally reduced. These two propulsion pipes are connected by accommodating the tip joint portion inside the collar, and at this time, the interior of the propulsion pipe is sealed by an elastically deformable annular packing provided between the inner surface of the collar and the outer surface of the tip joint portion.

[0004] In particular, unlike ordinary O-rings, this packing is formed long along the central axis, and is attached to the tip joint by a groove formed on the inner surface of the packing engaging with a rib formed to protrude locally on the outer surface of the tip joint. When the propulsion tube is attached or detached, a large force is applied to the packing in the attachment / detachment direction (a direction parallel to the central axis), but this structure prevents the packing from falling off the tip joint.

[0005] Meanwhile, multiple grooves are formed on the outer surface of the packing that abuts against the inner surface of the collar, but unlike the outer surface of the tip joint, no protrusions are formed on the inner surface of the collar. The formation of multiple grooves in this way allows the packing to deform easily during installation, making installation easier. Meanwhile, the inner surface of the collar and the outer surface of the packing abut at multiple points along the central axis, ensuring a reliable seal between them. In other words, using such a collar, tip joint, and packing makes it easy to connect the propulsion tube and seal the inside of the propulsion tube. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-336273 Summary of the Invention [Problem to be solved by the invention]

[0007] In the above structure, when the thrust pipe is connected, as mentioned above, a large force is applied to the packing in the direction along the central axis. In contrast, the packing with many grooves formed in this way becomes locally thin in the areas where the grooves are formed, making these areas more susceptible to fracture. As a result, this joint structure has the problem of the packing being easily damaged.

[0008] The present invention has been made in view of the above circumstances, and aims to solve the above problems. [Means for solving the problem]

[0009] The present invention provides a joint structure for a propulsion pipe for connecting cylindrical propulsion pipes along their central axes, the joint structure comprising: a collar serving as a first connecting portion formed on one end side of the propulsion pipe in the central axis direction; a tip joint portion serving as a second connecting portion provided on the other end side of the propulsion pipe in the central axis direction and having an outer diameter smaller than the inner diameter of the collar; and a packing that is sandwiched between the inner surface of the first connecting portion and the outer surface of the second connecting portion when the second connecting portion of one of the propulsion pipes is inserted into the inside of the first connecting portion of the other propulsion pipe to connect the two propulsion pipes, thereby sealing the gap between the inner surface of the first connecting portion and the outer surface of the second connecting portion, and a fixing protrusion that locally protrudes toward the packing is provided on either the inner surface of the first connecting portion or the outer surface of the second connecting portion. the packing is formed of an elastic material and includes, on a side where one of the inner surface of the first connecting part and the outer surface of the second connecting part is located, a surface that seals the gap between the inner surface of the first connecting part and the one of the outer surfaces of the second connecting part when the packing is attached; a fixing groove into which the fixing protrusion is housed in a loosely fitted state; and fixing ribs that protrude locally on the side where the other of the inner surface of the first connecting part and the outer surface of the second connecting part is located so as to seal the gap between the inner surface of the first connecting part and the other of the outer surfaces of the second connecting part when the packing is attached, and are formed at least on both sides of the fixing protrusion in the direction of the central axis, and the fixing groove is not formed in a location where the fixing rib is formed in the direction along the central axis. In the present invention, the packing is characterized in that an air hole is formed in the packing, which communicates the inside of the fixing groove with the side of the packing opposite to the side where the fixing groove is formed. In the present invention, the fixing protrusion is formed on the inner surface of the first connecting portion, and the packing is attached to the first connecting portion before the propulsion pipe is connected. In the present invention, the fixing protrusion is formed on the outer surface of the second connecting part, and the packing is attached to the second connecting part before the propulsion pipe is connected. [Effects of the Invention]

[0010] According to the present invention, in a joint structure for a propulsion pipe, damage to the packing that seals the space between two connected propulsion pipes can be suppressed when the two connected propulsion pipes are connected. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing a configuration in which a propulsion pipe using a joint structure according to an embodiment of the present invention is connected. [Figure 2] 1A and 1B are cross-sectional views of a joint structure according to an embodiment of the present invention (a: before connection, b: after connection). [Figure 3] 1A and 1B are cross-sectional views of a modified joint structure according to an embodiment of the present invention (a: before connection, b: after connection). DETAILED DESCRIPTION OF THE INVENTION

[0012] A joint structure for a propulsion pipe according to an embodiment of the present invention will be described. Fig. 1 is a cross-sectional view showing the overall configuration in which propulsion pipes 10 using this joint structure are connected to each other. Here, detailed descriptions of the features of each part (including the features of the present invention) are omitted, and all of the basic components of the propulsion pipe 10 are shown in a simplified form, and the configuration is the same as the structure described in Patent Document 1.

[0013] In FIG. 1, the jacking pipe 10 includes a jacking pipe body 11 made of concrete (reinforced concrete) and formed around a central axis X. A concentric, cylindrical metal collar (first connecting portion) 12 is fixed to the outer surface of the right end of the jacking pipe body 11. FIG. 1 shows a cross section of two jacking pipes 10, one on the left side and one on the right side, along the central axis X. The left end of the jacking pipe body 11 in the figure is formed as a tip joint portion (second connecting portion) 11A with a reduced outer diameter. When the jacking pipes 10 are connected, the tip joint portion 11A of the right jacking pipe 10 is inserted into the collar 12 of the left jacking pipe 10. At this time, a packing 20 made of an elastic material is provided between the outer surface of the tip joint portion 11A and the inner surface of the collar 12. A sealing layer may be provided between the right end of the jacking pipe body 11 of the left jacking pipe 10 and the left end of the tip joint portion 11A of the right jacking pipe 10.

[0014] To connect the right-side propulsion pipe 10 to the left-side propulsion pipe 10, the packing 20 is fixed to the inner surface of the collar 12 of the left-side propulsion pipe 10, and the tip joint portion 11A of the right-side propulsion pipe 10 is inserted into the inside of this collar 12.

[0015] 2 is a diagram showing in detail the structure (joint structure) in region Y in FIG. 1, where FIG. 2(a) shows the state before connection (the state without the tip joint portion 11A of the right-side thrust pipe 10), and FIG. 2(b) shows the state after connection (the state with the tip joint portion 11A of the right-side thrust pipe 10). This joint structure 1 is composed of a collar (first coupling portion) 12 provided at one end side (right side in the drawing) in the extension direction of the thrust pipe 10, a tip joint portion (second coupling portion) 11A provided at the other end side (left side in the drawing), and a packing 20 sandwiched between them. In this structure, the packing 20 is attached to the inner surface side of the collar 12 in the state before connection.

[0016] As shown in Fig. 2, collar 12 is provided with fixing protrusions 12A to 12C, in order from the right side in the figure, which locally protrude inward (towards central axis X: downward in the figure), and packing 20 is attached between fixing protrusions 12A and 12C in the horizontal direction (the direction of central axis X in Fig. 1). Although Fig. 2 shows the cross-sectional shapes of fixing protrusions 12A to 12C, this structure is axisymmetric about central axis X in Fig. 1, and fixing protrusions 12A to 12C are formed in a uniform annular shape around central axis X on collar 12, thereby mechanically reinforcing collar 12.

[0017] Meanwhile, at the location of the fixing protrusion 12B on the outer surface side (upper side in the figure) of the packing 20, a fixing groove 20A is formed by digging into the outer surface. As shown in Fig. 2, when the packing 20 is attached, the fixing protrusion 12B is located inside the fixing groove 20A. However, the shape of the inside of the fixing groove 20A in Fig. 2(a) does not match the shape of the inner surface side of the fixing protrusion 12B, and the fixing protrusion 12B is loosely fitted into the fixing groove 20A.

[0018] Furthermore, inner ribs (fixing ribs) 21A to 21D that locally protrude inward are formed in this order from the right side on the inner surface (lower side in the figure) of the packing 20. The inner ribs 21A, 21B, and 21C are formed to the right of the center of the fixing protrusion 12B, and the inner rib 21D is formed to the left of the center of the fixing protrusion 12B. The structure of the packing 20, including the fixing groove 20A and the inner ribs 21A to 21D, is also formed axially symmetrically around the central axis X in FIG. 1 (uniformly in the circumferential direction of the central axis X).

[0019] Moreover, the inner ribs 21A to 21D are all shaped to be inclined from the upper right to the lower left in Fig. 2. In Fig. 2(b), the tip joint part 11A is inserted from the right to the left, and by forming the inner ribs in this way, this insertion can be easily performed.

[0020] As shown in FIG. 2(a), the interior of the fixing groove 20A on the outer surface side of the packing 20 and the space on the inner surface side of the packing 20 are connected by an air hole 20B between the inner rib 21C and the inner rib 21D.

[0021] As described above, fixing groove 20A is formed uniformly in the circumferential direction as viewed from central axis X, whereas air holes 20B do not need to be formed uniformly in the circumferential direction but may be formed only in a portion in the circumferential direction, and the cross section shown in Figure 2(a) corresponds to the location in the circumferential direction where air holes 20B are formed. However, air holes 20B may be formed in multiple locations.

[0022] In Figure 2(a), the packing 20 can be fixed to the collar 12 by applying a thin layer of adhesive to the inner surface between the fixing protrusions 12A and 12B on the collar 12 and between the fixing protrusions 12B and 12C.

[0023] FIG. 2(b) shows a state in which the tip joint 11A is inserted from the right side of the state in FIG. 2(a). In this case, as shown in the figure, the collar 20 is compressed by the tip joint 11A from the bottom side in the figure. The deformation caused by this compression causes the fixing groove 20A to deform, but the provision of the air hole 20B makes this deformation easy. Also, as shown in FIG. 2(a), the packing 20 is particularly thin in the portion where the fixing groove 20A is formed. Without the air hole 20B, the pressure inside the fixing groove 20A increases with compression and deformation, making this portion particularly susceptible to rupture during installation, but this rupture is suppressed.

[0024] 2(b), the inner ribs 21A-21D are deformed from the state shown in FIG. 2(a) and press against the outer surface of the tip joint 11A. As a result, the inside of the propulsion tube 10 is sealed by the inner ribs 21A-21D. In this case, by providing the inner ribs 21A-21D separately, each inner rib is particularly easy to deform, which makes it easier to attach the collar 12 to the tip joint 11A while deforming the packing 20. Furthermore, the gap between the packing 20 and the outer surface of the tip joint 11A is sealed at four locations corresponding to the inner ribs 21A-21D.

[0025] 2(a) does not match the shape of the interior of the fixing groove 20A and the shape of the inner surface of the fixing protrusion 12B, and the fixing protrusion 12B is loosely fitted into the fixing groove 20A. If the shape of the interior of the fixing groove 20A and the shape of the inner surface of the fixing protrusion 12B were to match and fit together, the packing 20 could be more firmly fixed to the collar 12. However, in this case, when connecting the propulsion pipe 10, a particularly large force is applied to the portion where the fixing groove 20A is located, making this portion prone to breakage.

[0026] 2, the cross-sectional shape of fixing groove 20A is easily deformed when attached, making such breakage less likely to occur. Furthermore, since air holes 20B are provided in fixing groove 20A, this deformation becomes particularly easy.

[0027] Furthermore, the fixing groove 20A is provided between the inner rib 21C and the inner rib 21D, and is not formed in the locations where the inner ribs 21A to 21D are provided in the horizontal direction in the figure. If the fixing groove 20A were provided, the thickness of the packing 20 (in the vertical direction in the figure) would be thinner in this area, but this configuration ensures that this thickness is maintained in the locations where the inner ribs are provided. This makes it possible to increase the elastic force associated with the deformation of each inner rib, and to firmly fix the packing 20 to the tip joint portion 11A.

[0028] The fixing grooves 20A contribute to the ease of deformation of the packing 20 and also contribute to fixing the packing 20 to the collar 12. In this case, the fixing grooves 20A may be divided in the circumferential direction and formed in plurality in combination with the fixing protrusions 12B. In this case, it is preferable to provide an air hole 20B for each fixing groove 20A, as described above.

[0029] Figure 3 is a cross-sectional view similarly showing a joint structure 2 which is a modified example of the joint structure 1 shown in Figure 2. In this joint structure 2, a tip joint part (second connecting part) 31A, a collar (first connecting part) 32, and a packing 40 are used instead of the tip joint part 11A, collar 12, and packing 20, and the packing 40 is attached to the tip joint part 31A side, opposite to the packing 20.

[0030] Therefore, unlike the structure in FIG. 2, fixing protrusions 31AA, 31AB, and 31AC are provided on the outer surface (upper side in the figure) of tip joint 31A from the left in the figure, and the inner surface of collar 32 is flat.

[0031] Corresponding to the fixing groove 20A, inner ribs (fixing ribs) 21A to 21D protruding inward, and air hole 20B in the packing 20, this packing 40 is formed with a fixing groove 40A, outer ribs (fixing ribs) 41A to 41D protruding outward, and air hole 40B.

[0032] Fixing groove 40A and outer ribs 41A to 41D of packing 40 are formed on the opposite side to fixing groove 20A and inner ribs 21A to 21D of packing 20. The inside of fixing groove 40A communicates with the space on the outer surface side of packing 40 (between outer rib 41C and outer rib 41D) by air hole 40B.

[0033] Furthermore, when the propulsion pipe is connected to the state shown in Figure 3(b), the collar 32 moves from the left side to the right side in the figure, and accordingly the outer ribs 41A to 40D are shaped to be inclined from the lower left side to the upper right side in Figure 3(a).

[0034] 3, the work of connecting the thrust pipes is easy, and the inside of the thrust pipes can be sealed by the packing 40. At this time, the packing 40 is easily deformed during connection, so that breakage of the packing 40 is suppressed.

[0035] In the above example, three fixing ribs (inner ribs, outer ribs) are formed on either side of the fixing protrusion when mounted in the direction of the central axis X, one on each side. However, the number of fixing ribs is arbitrary as long as they are provided on both sides in this way.

[0036] Furthermore, in the above example, the propulsion pipe is assumed to be approximately cylindrical (the cross section perpendicular to the central axis is circular), but it is clear that a similar configuration can be realized even if the shape perpendicular to the central axis is, for example, approximately rectangular, as long as it is cylindrical.

[0037] The present invention has been described above based on an embodiment. This embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components, and that such modifications are also within the scope of the present invention. [Explanation of symbols]

[0038] 1, 2 Joint structure 10 Propulsion tube 11 Propulsion tube body 11A, 31A Tip joint (second connecting part) 12, 32 Collar (first connection) 12A~12C, 31AA~31AC Fixing protrusion 20, 40 packing 20A, 40A fixing groove 21A~21D Inner rib (fixing rib) 20B, 40BI air vents 41A~41D Outer ribs (fixing ribs)

Claims

1. A joint structure for a propulsion pipe for connecting cylindrical propulsion pipes along a central axis direction, a collar serving as a first connecting portion formed on one end side of the propulsion pipe in the central axis direction; a tip joint portion serving as a second connecting portion, the tip joint portion being provided on the other end side of the propulsion pipe in the central axis direction and having an outer diameter smaller than the inner diameter of the collar; a packing that is sandwiched between an inner surface of the first connecting portion and an outer surface of the second connecting portion when the second connecting portion of one of the propulsion pipes is inserted into the inside of the first connecting portion of the other propulsion pipe to connect the two propulsion pipes, thereby sealing the gap between the inner surface of the first connecting portion and the outer surface of the second connecting portion; Equipped with a fixing protrusion that locally protrudes toward the packing is provided on either an inner surface of the first connecting portion or an outer surface of the second connecting portion, The packing is formed of an elastic material, a surface that seals the gap between the inner surface of the first connecting portion and the outer surface of the second connecting portion when attached, on the side where the one of the inner surface of the first connecting portion and the outer surface of the second connecting portion is located, and a fixing groove into which the fixing protrusion is housed in a loosely fitted state; a fixing rib that locally protrudes on a side where the other of the inner surface of the first connecting portion and the outer surface of the second connecting portion is located so as to seal the gap between the inner surface of the first connecting portion and the outer surface of the second connecting portion when the connector is attached, and that is formed at least on both sides of the fixing protrusion in the central axis direction; Equipped with A joint structure for a thrust pipe, wherein in the packing, the fixing groove is not formed at a location where the fixing rib is formed in a direction along the central axis.

2. 2. The joint structure of a thrust pipe according to claim 1, wherein the packing has an air hole formed therein, the air hole communicating the inside of the fixing groove with the side of the packing opposite to the side where the fixing groove is formed.

3. 3. The joint structure of a thrust pipe according to claim 1, wherein the fixing protrusion is formed on an inner surface of the first connecting portion, and the packing is attached to the first connecting portion before the thrust pipe is connected.

4. 3. The joint structure of a thrust pipe according to claim 1, wherein the fixing protrusion is formed on an outer surface of the second connecting portion, and the packing is attached to the second connecting portion before the thrust pipe is connected.

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