Water stop plug

Abstract

To provide a water stop plug having a structure which can shorten an injection time of a pressure fluid to a hollow tube by using the water stop plug which uses the hollow tube, and does not cause damage when inserting the hollow tube into piping which stops water.SOLUTION: A water stop plug comprises a cylindrical core pipe 1, a hollow tube 2 formed of a shrinkable material which is expanded by being injected with a pressure fluid, and annular plates 5a, 5b attached to end faces of the core pipe at left-and-right both sides. Outside diameters of the annular plates are larger than an outside diameter of the core pipe, smaller than a tube outside diameter in an expansion state that the pressure fluid is injected into the hollow tube, and larger than the tube outside diameter in a shrink state that the pressure fluid is discharged, and an expansion width of the hollow tube in a radial direction is 50 to 150 mm.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a water stop plug (also called a water stop ball or a water stop valve) used to temporarily stop water from entering piping such as building water distribution pipes and water supply and sewerage pipes. [Background technology]

[0002] When replacing a portion of a pipe such as a building water distribution pipe or a water supply and sewerage pipe, or when working inside a manhole, it is necessary to temporarily stop water from entering the pipe in the work area. Examples of water-stopping plugs include those that use a cylindrical (bag-shaped) rubber tube (see Patent Document 1) and those that support both ends of a cylindrical tube with metal circular flanges (see Patent Document 2). These water-stopping plugs are brought in through a manhole or the like and inserted into the part of the pipe where water should be stopped, and are used by expanding the cylindrical hollow tube with pressurized fluid such as air or water to make it adhere to the inner wall of the pipe and block the inside of the pipe.

[0003] In addition, when replacing sewer pipes, there are cases where it is necessary to carry out the work without completely stopping the flow of water in the pipes. In such cases, water stop plugs are installed on both the upstream and downstream sides of the work area, and a bypass type water stop plug is also used, which connects a bypass flow path between these water stop plugs to continue the flow of water.

[0004] An example of a bypass type water stop plug is described in Patent Document 3. As shown in Figure 5, this water stop plug is formed by integrally joining together a cylindrical core tube 11 which forms part of the bypass flow path that allows running water to pass, metal flanges 13 and 14 which are fixed to the outer periphery of both ends of the core tube 11, and an annular hollow rubber tube 12 by insert molding.

[0005] When in use, water stop plugs are inserted into the upstream and downstream piping B on either side of the construction section, and pressurized fluid is injected into the hollow tube 12 from the injection port 15 provided in the flange 13 to expand (expand) the hollow tube 12 and pressurize it against the piping B. Then, a bypass pipe is connected to the connection ports 16 of the upstream and downstream water stop plugs to provide a bypass flow path.

[0006] The diameter of this connection port 16 and the diameter of the bypass pipe connected to connection port 16 are made small enough to allow running water to pass through without interfering with the bypass pipe so that the work space in the construction area is not occupied by the bypass pipe, and the diameter of the core pipe 11 continuing to connection port 16 is also made approximately the same as that of the bypass pipe. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 11-82864 [Patent Document 2] Practical Registration No. 3216785 [Patent Document 3] JP 2018-194020 A Summary of the Invention [Problem to be solved by the invention]

[0008] The sewer pipes, etc. to be sealed off can be relatively small pipes of around 200mm to 500mm in diameter, or large pipes with inner diameters of 500 to 1800mm, or even 3000mm or 5000mm, so large that a person must enter to work inside them. As for bypass-type waterstop plugs, as mentioned above, in order to ensure as much working space as possible in the construction area and to make them easy to transport into manholes, the diameters of the bypass flow path connection port and core tube have traditionally been made sufficiently small compared to the diameter of the pipe to be waterstopped.

[0009] However, the expansion volume of the tube from a deflated state before expansion, in which the outer surface of the tube is separated from the pipe wall, to a swollen state after expansion in which the tube is in close contact with the pipe wall increases as the outer diameter of the tube of the waterstop plug increases, and a large amount of pressurized fluid must be injected to expand the tube, which takes time to inject.

[0010] In order to shorten the injection time of pressurized fluid, it is necessary to reduce the expansion volume of the tube. However, if the diameter of the core tube is increased in order to reduce the expansion volume, and made closer to the diameter of the pipe to be watertight, the gap between the outer surface of the tube and the inner wall of the pipe will become smaller when the watertight plug is inserted into the watertight position of the pipe, and there is a risk that the outer surface of the tube will be damaged due to contact between the tube and the inner wall of the pipe.

[0011] On the other hand, in order to maintain stable watertightness, the higher the internal pressure of the pressurized fluid injected into the tube, the better. However, as the internal pressure becomes higher, the stress generated in the tube increases, increasing the risk of it bursting, so it is desirable to have a tube shape (dimensions) that can keep the stress generated in the tube as small as possible.

[0012] Therefore, from the viewpoint of the injection time of the pressurized fluid, it is preferable to make the diameter of the core tube larger, but it is even more preferable to determine the diameter of the core tube taking into consideration the safety issue of making it difficult for the tube to burst. In other words, it is preferable to determine the optimal outer diameter of the core tube and the optimal inner and outer widths (expansion widths) of the tube after considering how to reduce the stress generated in the tube by injecting the pressurized fluid, specifically, how to reduce the inner and outer widths (expansion widths) of the tube to reduce the stress generated in the tube.

[0013] The present invention aims to provide a waterstop plug that can shorten the injection time by minimizing the amount of pressurized fluid injected into the tube of the waterstop plug, and that uses a tube with a shape (dimensions) that makes it less likely to burst when pressurized fluid is injected.

[0014] Another object of the present invention is to provide a water stop plug that attaches a tube to the outer periphery of a core tube, yet can be transported and installed to a water stop position in a pipe without damaging the tube. [Means for solving the problem]

[0015] In order to solve the above problems, the present invention provides the following technical means. That is, the water stop plug of the present invention is a water stop plug used for water stop in a large-diameter pipe having an inner diameter of 500 to 5000 mm, and comprises a cylindrical core tube and a water stop plug attached to the outer circumferential surface of the core tube, which is expanded by injecting a pressurized fluid from an injection port. Cylindrical A water stop plug comprising a hollow tube made of a shrinkable material and annular plates removably attached to the left and right end faces of the core tube, the outer diameter of each annular plate being larger than the outer diameter of the core tube, smaller than the outer diameter of the hollow tube in an expanded state where a pressurized fluid is injected into the hollow tube, and larger than the outer diameter of the tube in a contracted state where the pressurized fluid is discharged, the hollow tube being positioned so as to be sandwiched between the left and right annular plates, and the radial expansion width of the hollow tube being 50 to 150 mm. Effect of the Invention

[0016] According to the present invention, the water-stop plug is composed of a core tube, a hollow tube, and an annular plate attached to the left and right end faces of the core tube. The outer diameter of the annular plate is larger than that of the core tube, smaller than the outer diameter of the tube in an expanded state in which pressure fluid is injected into the hollow tube, and larger than the outer diameter of the tube in a contracted state in which pressure fluid is discharged. Therefore, when inserting the water-stop plug into the water-stop position of the pipe, the hollow tube can be inserted in a state in which the hollow tube is in a contracted state and has a smaller diameter than the outer diameter of the annular plate. Even if the gap between the inner wall of the pipe and the core tube is reduced (to increase the diameter of the core tube), the hollow tube can be inserted while being protected by the annular plate from contacting the pipe wall. Then, by injecting pressure fluid into the hollow tube when it is set at the water-stop position, the tube outer diameter can be expanded to a diameter larger than the annular plate, and the hollow tube can be pressed against the pipe wall.

[0017] By doing this, the expansion width of the hollow tube required to pressurize the hollow tube (the difference between the inner and outer circumference of the hollow tube when water is stopped) can be kept to approximately 50 to 150 mm, the expansion volume of the hollow tube can be kept small, and the time required to inject pressurized fluid can be shortened.

[0018] Furthermore, it was confirmed by analytical calculations described below that the maximum stress generated in an annular hollow tube when pressurized fluid is injected into the tube is proportional to the expansion width. Therefore, even if the core tube is made larger in diameter and the expansion width of the hollow tube is reduced, it does not make it more likely to burst than when the conventional core tube is small in diameter, and no safety issues arise.

[0019] A bypass passage connection port having a diameter smaller than the outer diameter of the core tube may be attached to one of the annular plates. This allows the diameter of the bypass pipe connected to the water stop plug to be reduced, making it possible to ensure sufficient working space. Also, a closing plate for closing the opening may be attached to one end face of the core tube in place of the annular plate. [Brief description of the drawings]

[0020] [Figure 1] 1 is an exploded perspective view of a water stop plug according to one embodiment of the present invention; [Diagram 2] FIG. 4 is a cross-sectional view of the water stop plug shown in FIG. [Diagram 3] A graph showing the analytical calculation results for the relationship between the maximum stress σmax generated in the hollow tube and the expansion width a of the hollow tube. [Figure 4] FIG. 13 is a perspective view showing a closure plate used in another embodiment of the present invention. [Diagram 5] FIG. 1 is a diagram showing an example of a conventional water stop plug. BEST MODE FOR CARRYING OUT THEINVENTION

[0021] The water stop plug of the present invention will be described in detail below with reference to the following examples. Figures 1 and 2 are diagrams showing the configuration of a bypass-type water stop plug according to one embodiment of the present invention.

[0022] The water stop plug A of this embodiment includes a cylindrical core tube 1 made of metal or resin, and a contractible hollow tube 2 detachably attached around the core tube 1 and expanded by injecting a pressurized fluid such as air or water. The hollow tube 2 is made of natural or synthetic rubber having elasticity with excellent pressure resistance and capable of expanding and contracting, or a resin-coated contractible cloth material, or a composite material combining these materials, and includes an injection port 2a for injecting the pressurized fluid. For ease of explanation, the hollow tube 2 is shown in an inflated state in Fig. 1, and in Fig. 2, the deflated state is shown by a solid line, and the inflated state is shown by a two-dot chain line.

[0023] The hollow tube 2 is cylindrical and has a thickness in the radial direction when inflated by injecting pressurized fluid (e.g., water), and the difference between the inner and outer diameters in the inflated state (also called the inner and outer circumferential width or expanded width) is 50 to 150 mm. Needless to say, in order to be able to stop water, the outer diameter of the hollow tube 2 in the inflated state is of a size (larger than the inner diameter of the pipe B) that allows it to be pressed against the inner wall of the pipe B (see FIG. 2) that is the target for water stopping. The water stop plug of the present invention is used when the inner wall of the pipe B is 200 mm or more.

[0024] The inner diameter of the hollow tube 2 is such that the core tube 1 is pressed against it when the tube is inflated by injecting pressurized fluid, and the tube cannot be removed from the core tube 1 when inflated, but can be removed when deflated.

[0025] In this embodiment, the core tube 1 is made of aluminum material and formed by extrusion molding, with four thick-walled sections 3 formed along the axial direction. Four screw holes 9 for receiving screws are formed in the thick-walled sections 3 at the left and right ends of the core tube 1. Holes 4 for the injection port 2a to pass through are also machined.

[0026] An annular plate 5a and a connection port 6 are removably attached to the left end face of the core tube 1, and an annular plate 5b is removably attached to the right end face. Eight screw holes are formed in the annular plate 5a, and four screw holes are formed in the annular plate 5b. Four of the eight screw holes in the annular plate 5a and four of the screw holes in the annular plate 5b are formed so that they can be screwed into the positions of the four screw holes 9 in the core tube 1, and the remaining four of the eight screw holes in the annular plate 5a are formed so that they can be screwed into the four screw holes provided in the connection port 6 for bypass. Packings 7, 7 are interposed between the core tube 1 and the annular plates 5a, 5b, and a packing 8 is interposed between the annular plate 5a and the connection port 6 to provide a watertight seal.

[0027] The outer diameter of the annular plates 5a, 5b is larger than the outer diameter of the core tube 1, and the hollow tube 2 is sandwiched between the annular plates 5a, 5b so that its axial movement relative to the core tube 1 is restricted.

[0028] Furthermore, the outer diameter of the annular plates 5a, 5b is smaller than the outer diameter of the hollow tube 2 when it is inflated by injecting pressurized fluid, and is larger than the outer diameter of the tube when it is in a contracted state after the pressurized fluid is discharged. Also, the outer diameter of the annular plates 5a, 5b is smaller than the inner wall of the pipe B.

[0029] By ensuring that the outer diameter of the core tube 1 of the water stop plug A, the expanded width (inner and outer periphery width) of the hollow tube 2, and the outer diameters of the annular plates 5a and 5b satisfy the above-mentioned relationship, when the water stop plug A is attached to the piping B, if the hollow tube 2 is inserted into the piping B in a deflated state, the hollow tube 2 can be inserted while being protected by the annular plates 5a and 5b. Then, by injecting pressurized fluid from the injection port 2a while the hollow tube 2 is set in the water stop position, the hollow tube 2 expands and presses against the inner wall of the piping B and the core tube 1.

[0030] Depending on the unevenness of the surface of the pipe B at the water-stopping position where the hollow tube 2 is attached, it is also possible to first set only the hollow tube 2 in a deflated state at the water-stopping position of the pipe B, and then assemble the core tube 1 and annular plates 5a, 5b on the spot, thereby ensuring that damage due to contact when inserting the hollow tube 2 into the pipe B is eliminated.

[0031] Incidentally, it is desirable to determine the suitable sizes for the outer diameter of the core tube 1 and the expansion width of the hollow tube 2 from the viewpoints of shortening the time required to inject the pressurized fluid into the hollow tube 2 as quickly as possible, and of minimizing the stress generated in the hollow tube 2 when the pressurized fluid is injected to prevent bursting. Of these, the former point of shortening the injection time can be achieved by making the diameter (outer diameter) of the core tube 1 as large as possible within the range that does not interfere with the adhesion of the hollow tube 2 to the piping B, but the latter point of minimizing the stress generated in the hollow tube 2 must be determined through experiments or stress analysis.

[0032] Therefore, we performed an analytical calculation of the stress generated in the annular hollow tube 2. That is, as shown in Figures 1 and 2, we performed an analytical calculation of the relationship between the maximum stress (tangential stress along the axis σt, tangential stress along the circumferential direction σθ) acting on the hollow tube 2 sandwiched between the pipe wall B and the core tube 1, and the difference a between the outer diameter and inner diameter of the hollow tube 2 (expansion width a of the hollow tube 2).

[0033] The analytical calculation was performed using the finite element method (Marc Mentat 2012), and the annular hollow tube 2 shown in Figure 2 was analyzed. A shell element model was used for the analytical calculation, and the fixed conditions were that one end of the core tube 1 was closed with a blocking plate, the water pressure on the upstream side was 0 MPa, and the internal pressure in the hollow tube 2 was 1 MPa. The outer diameter φ of the core tube 1 was 500 mm, the axial length of contact between the hollow tube 2 and the core tube 1 and the pipe wall B was 500 mm, the wall thickness of the hollow tube 2 was 1 mm, and the friction coefficient was 0.3. The end of the hollow tube 2 was semicircular in shape, with a radius r of r=a / 2. The Young's modulus of the hollow tube 2 was 3.4 GPa, and the Poisson's ratio was 0.3. Then, the tangential stress σt along the axis and the tangential stress σθ along the circumferential direction were calculated when the expansion width a of the hollow tube 2 was changed to 100 mm, 150 mm, and 200 mm.

[0034] As a result, it was found that both the maximum stresses σt and σθ increased in proportion to the expansion width a, as shown in Figure 3. Therefore, from the viewpoint of not only shortening the injection time of the pressurized fluid but also reducing the stress generated in the hollow tube 2, it was found that it is preferable to make the core tube 1 larger in diameter and reduce the expansion width a of the hollow tube 2.

[0035] From the above, it is sufficient to reduce the expansion width a within a range that does not interfere with the adhesion of the hollow tube 2 to the piping wall (a range where the tube can adhere to the piping wall without being affected by unevenness or the like on the wall surface).

[0036] The inner diameter of pipes such as building water distribution pipes and water supply and sewerage pipes that must be watertight for work to be performed is around 200 to 5,000 mm, and for pipes of such diameter, even if the inner surface is uneven, it is sufficient to leave an expansion width a of around 50 mm to 150 mm, preferably around 100 mm. Therefore, if the diameter of core pipe 1 is set to the remainder after subtracting an expansion width of around 50 mm to 150 mm from the inner diameter of the pipe, a preferable watertight plug can be made.

[0037] Next, we will explain how to use the water stop plug A. Figure 2 shows the state in which the water stop plug A is installed inside the pipe B. A bypass flow path is formed by connecting flexible bypass pipes 13 to each connection port 6 of the water stop plugs installed inside the upstream and downstream pipes B, and water is injected as a pressurized fluid into the hollow tube 2 to expand it and seal it against the inner surface of the pipe B to stop the water from entering. After installation is completed, each component is disassembled and removed from the pipe.

[0038] Thus, the water stop plug of the present invention prevents damage to the hollow tube caused by rough insertion and removal, and prevents bursting during use. In addition, the diameter of the core tube is increased to reduce the volume (expansion width) of the hollow tube to be expanded, so that the hollow tube can be tightly attached to the inner surface of the pipe with only a small expansion caused by injection of a relatively small amount of pressure fluid, and the injection time of pressure fluid required for water stop can be shortened. In addition, by making the diameter of the connection port smaller than the diameter of the core tube, a bypass flow path can be created according to the required flow rate of water, and a flexible pipe with a small diameter that is easy to handle can be connected. As a result, even if the diameter of the core tube is made thicker, the connection port and bypass pipe can be made to have the same pipe diameter as before, so that the work space in the construction area is not occupied.

[0039] Although typical examples of the present invention have been described above, the present invention is not necessarily limited to the above-described embodiments. In the above embodiment, an example was shown in which the present invention was applied to a bypass type water stop plug. However, it is also possible to form a water stop plug for complete sealing by completely blocking one end face of the core tube 1 using a blocking plate 10 as shown in FIG. 4. In addition, the present invention can be modified or changed as appropriate without departing from the scope of the claims, while achieving its object. [Industrial Applicability]

[0040] INDUSTRIAL APPLICABILITY The present invention can be used as a water stop plug for temporarily stopping water flow in piping such as building water distribution pipes and water supply and sewerage pipes. [Explanation of symbols]

[0041] A Water stop plug B Piping 1 core tube 2 Hollow tube 2a inlet 3 Thick part 5a Annular plate 5b Annular plate 6 Connection port 7 Packing 8. Packing 10 Occlusion plate

Claims

1. A water stop plug used for stopping water in a large diameter pipe having an inner diameter of 500 to 5000 mm, A cylindrical core tube; a hollow tube attached to an outer circumferential surface of the core tube and made of a contractible material that expands into a cylindrical shape when a pressurized fluid is injected through an injection port; annular plates detachably attached to the left and right end faces of the core tube, an outer diameter of each of the annular plates is larger than an outer diameter of the core tube, smaller than an outer diameter of the tube in an expanded state in which a pressure fluid is injected into the hollow tube, and larger than an outer diameter of the tube in a contracted state in which the pressure fluid is discharged; The hollow tube is disposed so as to be sandwiched between the left and right annular plates, A watertight plug, wherein the radial expansion width of the hollow tube is 50 to 150 mm.

2. 2. The water stop plug according to claim 1, wherein a connection port for connecting a bypass flow passage having a diameter smaller than an outer diameter of the core tube is attached to one of the annular plates.

3. 2. The water stop plug according to claim 1, wherein a closing plate for closing the opening is attached to one end face of the core tube in place of the annular plate.

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