Pipe fittings

Abstract

To provide a pipe joint equipped with a backflow prevention part.SOLUTION: There is provided a pipe joint comprising a joint body 10 which is formed in a tubular shape, a horizontal pipe connecting portion 14 whose end portion is connected to the side surface of the joint body 10, having an opening formed in the end portion which communicates with the inside of the joint body, a bush 25 fitted to the horizontal pipe connecting portion 14 and to which the horizontal pipe is connected, and a backflow prevention part 29 formed on the bush 25 so as to project from the inner peripheral surface of the joint body 10 toward the inside of the joint body 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pipe joint provided with a backflow prevention portion. [Background technology]

[0002] BACKGROUND ART Resin drainage collecting pipes such as those described in the following Patent Documents 1 to 3 have been known in the past. The drainage collecting pipe described in Patent Document 1 has a structure in which multiple horizontal branch pipes are connected to a vertical pipe body, multiple vertical ribs for preventing backflow that extend in the axial direction of the pipe are provided on the inside of the vertical pipe body, and swirling blades for swirling the fluid are provided on the inside of the vertical pipe body. Patent Document 2 discloses a drainage collection pipe in which multiple horizontal drainage pipes are connected to a vertical pipe at different levels, and a backflow prevention part is provided to prevent a portion of the drainage from flowing back into the horizontal water distribution pipe below when the drainage flows from the upper horizontal drainage pipe into the vertical pipe. This backflow prevention part is provided in the shape of a canopy so as to be located above the drainage outlet where the lower horizontal drainage pipe is connected to the pipe wall of the vertical pipe. Patent document 3 discloses a configuration in which a collecting joint is constructed by connecting multiple horizontal branch pipes to a vertical pipe, in which multiple vertical ribs are provided on the inner wall of the vertical pipe, and these vertical ribs prevent backflow into the horizontal branch pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-085014 [Patent Document 2] Japanese Patent Application Publication No. 9-273197 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-106157 Summary of the Invention [Problem to be solved by the invention]

[0004] In a plastic drainage collecting pipe connected to multiple horizontal branch pipes, if a structure with eaves or vertical ribs integrally formed inside is adopted, there is a problem that the structure of the mold for molding the drainage collecting pipe becomes complicated. For example, when molding a drainage collecting pipe with integrated vertical ribs, there is a risk of sink marks occurring in the thick vertical rib portions due to resin shrinkage, which may cause deformation of the drainage collecting pipe. This results in a problem that there are certain limitations on the shapes of eaves and vertical ribs that can be formed on the drainage collecting pipe. Although it is possible to form the vertical ribs only along the direction parallel to the direction in which the mold is removed during molding using a mold, this creates a problem in that the shape of the vertical ribs is restricted.

[0005] Furthermore, a blade member for adjusting the water flow is provided inside the drainage collecting pipe, but the position where the blade member is provided is limited to a position where it does not interfere with the vertical ribs.

[0006] In view of the above-mentioned circumstances, the present invention aims to provide a pipe fitting that can be molded without complicating the mold structure and without producing molding defects such as sink marks in the backflow prevention part, even if it is a pipe fitting that has a drainage manifold with a backflow prevention part. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention proposes the following aspects. "1" The pipe fitting of this embodiment is characterized by having a fitting body formed in a cylindrical shape, a horizontal pipe connection part whose end is connected to the side of the fitting body and whose opening formed at the end is connected to the inside of the fitting body, a bushing that is fitted into the horizontal pipe connection part and to which the horizontal pipe is connected, and a backflow prevention part that protrudes from the inner surface of the fitting body toward the inside of the fitting body and is formed on the bushing.

[0008] Since the bushing is provided with a backflow prevention portion, by joining the bushing to the horizontal pipe connection portion of the fitting body, a backflow prevention portion can be formed that protrudes from the inner peripheral surface of the fitting body toward the interior of the fitting body. Because this backflow prevention portion is located near the horizontal pipe connection portion, it prevents water flowing inside the fitting body from flowing back into the horizontal pipe. The bushing equipped with the backflow prevention portion can be configured separately from the fitting body, and when molding the fitting body, there is no need to consider the formability of the configuration including the backflow prevention portion. Therefore, even if the pipe fitting is configured with a backflow prevention portion, it does not make it difficult to mold the fitting body.

[0009] [2] The pipe joint according to this embodiment may employ a configuration in which a small diameter protrusion is formed on the tip side of the bush, and the bush is positioned by fitting the small diameter protrusion into the horizontal pipe connecting portion.

[0010] By fitting the small-diameter protrusion of the bushing into the opening of the horizontal pipe connection, the bushing can be positioned relative to the horizontal pipe connection, and this positioning allows the backflow prevention part on the bushing to be installed at the desired position within the fitting body. By installing the backflow prevention part at the desired position, the desired backflow prevention effect can be achieved.

[0011] "3" In the pipe fitting according to this embodiment, a configuration can be adopted in which an insertion hole for inserting the horizontal pipe is formed in the bush, and a locking protrusion for regulating the insertion depth of the horizontal pipe is formed at the opening of the insertion hole located on the tip side of the bush.

[0012] If a locking projection is provided at the opening of the insertion hole of the joint body, when the horizontal pipe is inserted into the insertion hole of the bushing, the locking projection acts as a stopper that determines the insertion position of the horizontal pipe.

[0013] "4" The pipe fitting of this embodiment comprises a fitting body formed in a cylindrical shape, a horizontal pipe connection part whose end is connected to the side of the fitting body and whose opening formed at the end communicates with the interior of the fitting body, allowing a horizontal pipe to be connected, and a branch plug member that fits into the opening of the horizontal pipe connection part and closes the horizontal pipe connection part, and is characterized in that a backflow prevention part that protrudes from the inner surface of the fitting body toward the interior of the fitting body is formed on the branch plug member.

[0014] Since the branch plug member is provided with a backflow prevention part, by joining the branch plug member to the horizontal pipe connecting part of the joint body, a backflow prevention part can be formed that protrudes from the inner peripheral surface of the joint body toward the inside of the joint body. Because this backflow prevention part is located near the horizontal pipe connecting part, it prevents water flowing inside the joint body from flowing back into the horizontal pipe near the branch plug member. The branch plug member equipped with the backflow prevention part can be constructed separately from the joint body, and when molding the joint body, there is no need to consider moldability of the structure including the backflow prevention part. Therefore, even if the pipe joint is configured with a backflow prevention part, it does not make it difficult to mold the joint body.

[0015] "5" In the pipe fitting of this embodiment, the horizontal pipe connection portions are formed at positions spaced apart along the axial direction of the fitting body and alternately facing each other across the axis of the fitting body, and a configuration can be adopted in which the backflow prevention portion is provided in the horizontal pipe connection portion installed lower than the pair of horizontal pipe connection portions facing each other across the axis.

[0016] If the backflow prevention part is a backflow prevention rib that protrudes from the inner surface of the fitting body toward its axis and extends in the axial direction, it can efficiently block the flow path that would otherwise prevent water flowing inside the fitting body from flowing into the horizontal pipe, making it easier to achieve the desired backflow prevention effect.

[0017] [6] In the pipe joint according to this aspect, a configuration can be adopted in which a plurality of the horizontal pipe connecting portions are formed in the circumferential direction of the joint body.

[0018] A pipe fitting having multiple horizontal pipe connections in the circumferential direction of the fitting body is a structure that makes it easier to obtain the backflow prevention effect of the backflow prevention part. For example, if multiple adjacent horizontal pipe connections are formed, the backflow prevention part of the bushing provided at a specific horizontal pipe connection part will exert a backflow prevention effect on the other adjacent horizontal pipe connections.

[0019] "7" In the pipe fitting of this embodiment, the horizontal pipe connection portions are formed at positions spaced apart along the axial direction of the fitting body and facing each other alternately across the axis of the fitting body, and a configuration can be adopted in which the backflow prevention portion is provided in the horizontal pipe connection portion installed lower than the pair of horizontal pipe connection portions facing each other across the axis.

[0020] When horizontal pipe connection sections are formed at alternately opposing positions on the fitting body, water may flow from the upper horizontal pipe connection section to the lower horizontal pipe connection section. Even in this structure, by providing a backflow prevention section, it is possible to make it less likely for backflow to occur in the horizontal pipe.

[0021] [8] In the pipe joint according to this embodiment, a configuration can be adopted in which swirl vanes are provided in the joint body to swirl the flow of water passing through the joint body.

[0022] If a swirl vane is provided inside the joint body, water can be made to flow in a swirling state inside the joint body. The swirling flow inside the joint body may cause a portion of the swirling flow to reach the horizontal pipe side via the horizontal pipe connection portion, causing a backflow, but the backflow prevention portion blocks a portion of this swirling flow, thereby preventing a backflow. [Effects of the Invention]

[0023] According to the pipe fitting of this embodiment, the bushing is provided with a backflow prevention portion, so that by joining the bushing to the horizontal pipe connecting portion of the fitting body, a backflow prevention portion can be formed that protrudes from the inner peripheral surface of the fitting body toward the interior of the fitting body. Because this backflow prevention portion can be located near the horizontal pipe connecting portion, it is possible to prevent water flowing inside the fitting body from flowing back into the horizontal pipe. The bushing equipped with the backflow prevention portion can be configured separately from the fitting body, and when molding the fitting body, there is no need to consider the formability of the configuration including the backflow prevention portion. Therefore, even if the fitting body is configured with a backflow prevention portion, it can be molded without making the fitting body difficult to mold. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a vertical cross-sectional view showing a pipe joint according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a development view showing the component configuration of the pipe joint shown in FIG. [Figure 3] FIG. 2 is a plan view showing an upper connecting pipe of the pipe joint according to the first embodiment. [Figure 4] FIG. 3 is a cross-sectional view showing the structure of a connecting portion in a bush of the pipe joint according to the first embodiment. [Figure 5] FIG. 2 is a perspective view of a bush provided in the pipe joint according to the first embodiment, as viewed from the rear end side. [Figure 6] FIG. 2 is a perspective view of a bush provided in the pipe joint according to the first embodiment, as viewed from the tip side. [Figure 7] FIG. 4 is a cross-sectional view showing the structure of a connecting portion in a bush of a pipe joint according to a first modified example of the first embodiment. [Figure 8] FIG. 10 is a perspective view of a bush provided in a pipe joint according to a first modified example of the first embodiment, as viewed from the tip end side. [Figure 9] FIG. 10 is a cross-sectional view showing the structure of a connecting portion in a bush of a pipe joint according to a second modified example of the first embodiment. [Figure 10] FIG. 10 is a perspective view of a bush provided in a pipe joint according to a second modified example of the first embodiment, as viewed from the tip end side. [Figure 11] FIG. 4 is a vertical cross-sectional view showing a pipe joint according to a second embodiment of the present invention. [Figure 12] FIG. 10 is a perspective view showing a modified example of a backflow prevention member provided in the pipe joint. [Figure 13] FIG. 10 is a plan view showing another modified example of the backflow prevention member provided in the pipe joint. DETAILED DESCRIPTION OF THE INVENTION

[0025] [First embodiment] Hereinafter, a joint structure equipped with a pipe joint according to a first embodiment of the present invention will be described with reference to the drawings. The pipe joint 1 is used, for example, for drainage of a building, and is arranged in a slab penetration hole formed in a floor slab. 1 and 2, a pipe fitting 1 according to this embodiment includes a fitting body (pipe fitting) 10. The fitting body 10 includes an upper connecting pipe 11, a lower connecting pipe 12, and an intermediate pipe 15 that connects the upper connecting pipe 11 and the lower connecting pipe 12. The upper connecting pipe 11 has a vertical pipe connecting portion 13 that can be connected to a first vertical pipe P1, and a horizontal pipe connecting portion 14 that protrudes from the side surface of the vertical pipe connecting portion 13 and can be connected to a horizontal pipe P3.

[0026] The pipe joint 1 of this embodiment is installed on a floor slab 8, for example, as shown in FIG. The upper end of the intermediate pipe 15 is inserted into the lower end of the upper connecting pipe 11 and fixed to the upper connecting pipe 11 by adhesive or the like, and the connection portion between the upper side of the intermediate pipe 15 and the lower side of the upper connecting pipe 11 is inserted into the through hole 8a in the floor slab 8. Then, outside the connection portion between the intermediate pipe 15 and the upper connecting pipe 11 and inside the through hole 8a in the floor slab 8, a filler 9 such as mortar is filled, and this filler 9 blocks the through hole 8a on the outside of the joint body 10.

[0027] The upper connecting pipe 11, the lower connecting pipe 12 and the intermediate pipe 15 are made of a flame-retardant resin such as vinyl chloride. The intermediate pipe 15 is connected to the lower end of the upper connecting pipe 11. In the illustrated example, the upper end of the intermediate pipe 15 is fitted into the lower end of the vertical pipe connecting part 13. The intermediate pipe 15 contains, for example, a resin composition containing polyvinyl chloride resin and thermally expandable graphite.

[0028] The intermediate tube 15 may have a single-layer structure in which the entire intermediate tube 15 is made of a resin composition, or may have a multi-layer structure made of multiple layers. In the case of a multi-layer structure, any one of the layers may be formed from a resin composition. For example, when the intermediate tube 15 has a three-layer structure consisting of a surface layer, an intermediate layer, and an inner layer, the intermediate layer may be formed from a resin composition.

[0029] Furthermore, for example, if the intermediate pipe 15 has a three-layer structure, the surface layer, intermediate layer, and inner layer may contain a heat-absorbing agent. The intermediate layer may contain thermally expandable graphite and therefore have a black color. If the intermediate pipe 15 does not contain thermally expandable graphite, a sheet-like fire-resistant material containing thermally expandable graphite may be wrapped around the outer surface of the intermediate pipe 15 or the outer surface of the sound-insulating material provided to cover the intermediate pipe 15, and the fire-resistant material may be embedded in the slab penetration portion. The thermally expandable graphite and refractory material used in the intermediate tube 15 will be explained later.

[0030] The vertical pipe connecting portion 13 is formed in a tubular shape. The first vertical pipe P1 is connected to a first end (upper end) of the vertical pipe connecting portion 13, and the lower connecting pipe 12 is connected to a second end (lower end) thereof via an intermediate pipe 15. In the following description, the first vertical pipe P1 side along the central axis O of the vertical pipe connecting portion 13 will be referred to as the upper side, and the lower connecting pipe 12 side will be referred to as the lower side.

[0031] The lower connecting pipe 12 is tubular and has a smaller diameter at the bottom than at the top. The lower connecting pipe 12 includes a connecting pipe section 16 connected to the intermediate pipe 15, an inclined pipe section 17 extending downward from the connecting pipe section 16 and gradually decreasing in diameter as it extends downward, and a lower pipe section 18 provided at the lower end of the inclined pipe section 17 and to which a second vertical pipe P2 is connected. The intermediate pipe 15 is fitted into the connecting pipe section 16. The second vertical pipe P2 is fitted into the lower pipe section 18. The connecting pipe section 16, inclined pipe section 17, and lower pipe section 18 are integrally formed from, for example, a synthetic resin material.

[0032] A first bush 21, a first packing 22, and a first ring 23 are provided at the upper end of the upper connecting pipe 11 (the upper end of the vertical pipe connecting portion 13). The first bushing 21 includes a fitting portion 21a, a support portion 21c, and a first swirl vane 21b. The fitting portion 21a is formed in a tubular shape that fits into the vertical pipe connection portion 13. The support portion 21c extends downward from the fitting portion 21a. The first swirl vane 21b is provided at the lower end of the support portion 21c. The first swirl vane 21b extends around the central axis O.

[0033] The first packing 22 is fitted into the first bushing 21. The upper end of the first packing 22 is provided with a lip portion 22a that comes into close contact with the outer peripheral surface of the first vertical pipe P1. The lower end of the first packing 22 is formed with an upwardly facing step portion 22b. The lower end of the first vertical pipe P1 abuts against this step portion 22b.

[0034] The first ring 23 is fitted from the outside onto the upper end of the first bushing 21. A flange portion 23a is provided on the upper end of the first ring 23. The flange portion 23a prevents the first packing 22 from coming off the first bushing 21. The first bushing 21, the first packing 22 and the first ring 23 can be pre-assembled and integrated before being attached (bonded) to the upper connecting pipe 11.

[0035] The horizontal pipe connecting portion 14 is cylindrical and protrudes from the outer circumferential surface of the vertical pipe connecting portion 13 in a direction extending approximately perpendicular to the central axis O of the vertical pipe connecting portion 13. In the example shown in FIGS. 1 to 3, two horizontal pipe connecting portions 14 are arranged with a gap between them around the central axis O. The two horizontal pipe connecting portions 14 are formed in directions that form a 90° angle around the central axis O in top view, and therefore only one of the horizontal pipe connecting portions 14 is depicted in FIG. 1. The number and extending direction of the horizontal pipe connecting portions 14 are not limited to this embodiment and can be changed as desired.

[0036] 1 and 4, a horizontal pipe P3 is connected to the horizontal pipe connecting portion 14 via a bushing 25 as shown below. The horizontal pipe P3 in this embodiment is a small-diameter pipe whose diameter is smaller than the inner diameter of the opening of the horizontal pipe connecting portion 14. The bushing 25 includes a horizontal pipe joint main body 26, an annular second packing 27 attached to one side (entrance side) of the horizontal pipe joint main body 26, and a cover member 28. The horizontal pipe joint main body 26 is of a single cylindrical shape, and the first end 26A side (tip side) of the horizontal pipe joint main body 26 is inserted into the opening of the horizontal pipe connection portion 14, and the second end 26B side (rear end side) of the horizontal pipe joint main body 26 protrudes outside the horizontal pipe joint portion 14. A small-diameter cylindrical partition wall 26a is formed inside the horizontal pipe joint main body 26, with its axis C2 slightly offset radially downward from the central axis C1. An insertion hole 26b is formed inside this partition wall 26a. The end of the horizontal pipe P3 is inserted into this insertion hole 26b.

[0037] In the horizontal pipe joint main body 26, a closing portion 26D that closes the horizontal pipe connecting portion 14 is formed on the first end 26A side, and a large diameter portion 26E is formed on the second end 26B side. An inner peripheral step 26c is formed on the inner periphery of the insertion hole 26b of the horizontal pipe joint main body 26 on the inlet side (second end 26B side), and a ring-shaped second packing 27 is inserted into this inner peripheral step 26c. A lip 27a that contacts the outer periphery of the horizontal pipe P3 is formed on the inner periphery of the second packing 27. An opening 26d on the first end 26A side (outlet side) of the insertion hole 26b opens to a tip end face 26e of the closing portion 26D.

[0038] A small-diameter protrusion 26f is formed by forming an outer circumferential step on the first end 26A side of the horizontal pipe joint main body 26. By inserting this small-diameter protrusion 26f into the opening of the cylindrical horizontal pipe connecting part 14, the horizontal pipe joint main body 26 is fitted into the horizontal pipe connecting part 14, and the insertion depth of the horizontal pipe joint main body 26 is determined. In this fitted state, the tip end 14a of the horizontal pipe connecting portion 14 abuts against the corner 26g on the base end side of the small diameter protrusion 26f, thereby restricting the insertion depth of the horizontal pipe joint main body 26 into the upper connecting pipe 11. Therefore, the corner 26g functions as a stopper that restricts the insertion depth of the horizontal pipe joint main body 26.

[0039] Furthermore, when the tip 14a of the horizontal pipe connecting portion 14 is in contact with the corner 26g, the tip surface 26e of the closing portion 26D is disposed at a position along the inner peripheral wall of the upper connecting pipe 11. Further, the small diameter protruding portion 26f is formed with a recess 26U recessed from the tip surface 26e of the closing portion 26D toward the second end 26B side. When viewed from the first end 26A side (tip side), the recess 26U is formed in an arc shape with the upper side positioned on the inner circumferential side with a predetermined thickness away from the upper surface of the small diameter protrusion 26f, and the lower side is formed in an arc shape with the upper side positioned on the inner circumferential surface of the opening 26d with a thickness of the partition wall 26a away from it, and the left and right sides are formed inside the inner surfaces of the vertical ribs 291 described later. The shape of the recess 26U when viewed from the first end 26A side (tip side) is not limited to the above and may be set arbitrarily.

[0040] A cap 26S is fitted into the recess 26U, thereby preventing wastewater from entering the recess 26U and from accumulating in the recess 26U. It is possible to arbitrarily determine whether or not to form the recess 26U in the small diameter protruding portion 26f, and whether or not to insert the cap 26S when the recess 26U is formed.

[0041] Furthermore, a locking projection 26h that projects downward is formed on the upper inner peripheral side of the opening 26d of the insertion hole 26b. This locking projection 26h acts as a stopper for the horizontal tube P3 when the end of the horizontal tube P3 is inserted into the insertion hole 26b, and determines the insertion depth of the horizontal tube P3 into the insertion hole 26b. There are no particular restrictions on the height or width of the locking projection 26h that projects inward from the opening 26d, as long as it is high enough to abut against the tip of the horizontal tube P3 and prevent the horizontal tube P3 from entering.

[0042] A backflow prevention portion 29 is formed on the tip end surface 26e of the closed portion 26D of the horizontal pipe joint main body 26. In this embodiment, the backflow prevention portion 29 includes a pair of left and right vertical ribs (backflow prevention ribs) 291 that protrude from the tip end surface 26e. The vertical rib (backflow prevention rib) 291 is disposed so as to protrude toward the axial center of the joint body 1 (upper connecting pipe 11) and extend in the axial direction (vertical direction) of the joint body 1 (upper connecting pipe 11). An opening 26d of the insertion hole 26b is formed in the tip surface 26e of the horizontal pipe joint body 26, and the above-mentioned vertical ribs (backflow prevention ribs) 291 are formed on both sides of the opening 26d so as to sandwich this opening 26d from the left and right. In this configuration, the vertical length (height) of the vertical rib (backflow prevention rib) 291 is made approximately equal to the inner diameter of the opening 26d.

[0043] The height of the vertical rib (backflow prevention rib) 291 does not have to be limited to a height approximately equal to the inner diameter of the opening 26d, and may be slightly larger or slightly smaller than the inner diameter of the opening 26d. When the blocking portion 26D of the horizontal pipe joint main body 26 is fitted into the opening of the horizontal pipe connecting portion 14, the height need only be lower than the height at which the vertical rib 291 can pass through the opening of the horizontal pipe connecting portion 14. To obtain a sufficient backflow prevention effect, it is desirable that the height of the vertical rib 291 be high, but the height should be such that the vertical rib 291 does not interfere with fitting the horizontal pipe joint main body 26 into the opening of the horizontal pipe connecting portion 14. The shape of the vertical rib (backflow prevention rib) 291 and its positional relationship with the horizontal pipe joint main body 26 are also shown in the perspective views of FIGS.

[0044] In addition, it is desirable to limit the protruding length of the vertical rib (backflow prevention rib) 291, in other words, the width of the vertical rib 291 protruding from the inner surface of the upper connecting pipe 11 toward the central axis O, as described below. The vertical rib (backflow prevention rib) 291 preferably has a protruding height toward the central axis O that can avoid interference with wastewater flowing down from the riser pipe connection part 13 side. The wastewater flowing down from the riser pipe connection part 13 side here means wastewater flowing down from the first riser pipe P1 inserted into the riser pipe connection part 13. For example, the overhang length that can avoid interference with wastewater flowing down from the vertical pipe connection portion 13 is the overhang length that, when viewed in vertical cross section as shown in Figure 1, does not protrude toward the central axis O beyond the inner peripheral end of the inward flange portion 21d formed at the lower end of the first bushing 21 or the inner peripheral end of the inward flange portion 22d at the lower end of the first gasket 22 arranged above it.

[0045] In this embodiment, the vertical rib (backflow prevention rib) 291 is in the shape of a vertically long rectangular plate, but the backflow prevention rib may be in the shape of a curved plate, for example, a plate-shaped backflow prevention rib that curves along the outer peripheral surface of the blocking portion 26D. There is also no particular limit to the number of vertical ribs 291 provided, and there may be one on the side of the opening 26d, or, for example, a single-tube backflow prevention rib that protrudes forward from the tip surface 26e of the blocking portion 26D. When the vertical ribs (backflow prevention ribs) 291 are provided, they do not need to be parallel to each other, and may be formed in different directions, or may be formed in a direction other than toward the central axis O. Regardless of the direction in which the vertical ribs (backflow prevention ribs) 291 are oriented, it is sufficient that they are formed in a position that can block or suppress the flow of wastewater that attempts to flow back from the opening 26d into the interior of the horizontal pipe P3.

[0046] Furthermore, a second swirl vane 30 is provided inside the intermediate pipe 15, and a third swirl vane 31 is provided inside the lower connecting pipe 12. Similar to the first swirl vane 21b, the second swirl vane 30 and the third swirl vane 31 both function to make the wastewater flowing down inside the joint body 10 a swirling flow. The first swirl vane 21b, the second swirl vane 30, and the third swirl vane 31 are not essential components, and any one of them may be omitted, or all of them may be omitted.

[0047] For the intermediate tube 15, a thermal expansion tube containing a resin composition (A) containing a polyvinyl chloride resin and a heat-absorbing agent, or a resin composition (B) containing a polyvinyl chloride resin and thermally expandable graphite having a thermal expansion starting temperature of 240°C or higher can be used. The intermediate pipe 15 is preferably disposed below the lower end of the longitudinal rib (backflow prevention rib) 291.

[0048] The polyvinyl chloride resin contained in the resin composition (A) is, for example, a polyvinyl chloride homopolymer, a copolymer of a vinyl chloride monomer and another monomer having an unsaturated bond copolymerizable with the vinyl chloride monomer, a graft copolymer in which a vinyl chloride monomer is graft-copolymerized onto a polymer other than a polyvinyl chloride resin, etc. The polyvinyl chloride resin may be used alone or in combination of two or more. The endothermic agent contained in the resin composition (A) is a compound that exhibits an endothermic effect when heated and suppresses temperature rise. For example, a compound that undergoes an endothermic reaction such as a dehydration reaction when heated can be used as the endothermic agent.

[0049] The polyvinyl chloride resin contained in the resin composition (B) may be the same as the polyvinyl chloride resin contained in the resin composition (A). The thermally expandable graphite contained in the resin composition (B) has a thermal expansion starting temperature of 240°C or higher, preferably 260°C or higher.

[0050] Next, the operation of the pipe joint 1 configured as described above will be described, focusing on the joint body 10. In a building, wastewater from upper floors flows into the joint body 10 through the first vertical pipe P1. The wastewater that flows into the joint body 10 is converted into a swirling flow through the first swirl vane 21b, the second swirl vane 30, and the third swirl vane 31 and is guided downward. When the swirling flow of wastewater passes near the horizontal pipe connecting portion 14, there is a risk that some of the wastewater will flow back into the interior of the horizontal pipe P3 from the opening 26d, but the vertical ribs (backflow prevention ribs) 291 provided on both the left and right sides of the opening 26d block or suppress this backflow. Therefore, the above-mentioned structure can provide a structure that can prevent the backflow of wastewater into the horizontal pipe P3.

[0051] According to the pipe fitting 1 of this embodiment, the vertical rib (backflow prevention rib) 291 has a protruding height toward the central axis O that is sufficient to prevent interference with wastewater flowing downward from the vertical pipe connecting portion 13. This prevents the wastewater flowing down from the vertical pipe connecting portion 13 from directly hitting the vertical rib 291. Therefore, it is less likely that the wastewater will directly hit the vertical ribs (backflow prevention ribs) 291, and it is possible to suppress the generation of noise (abnormal noise) that would be caused by the wastewater hitting the vertical ribs 291. Therefore, even if there are building users near the pipe fitting 1, it is possible to reduce the risk of complaints about noise.

[0052] According to the pipe fitting 1 of this embodiment, the vertical ribs (backflow prevention ribs) 291 can be configured as an integrally molded resin product together with the bushing 25, and can be configured as a separate part from the fitting body 10 (upper connecting pipe 11). Therefore, the configuration of this embodiment can be realized without requiring a complex mold for molding the fitting body 10 (upper connecting pipe 11). Furthermore, since the configuration in which the vertical ribs 291 are provided on the bushing 25 is not complex, a complex mold for molding them is not required, and the configuration can be easily realized.

[0053] The vertical ribs (anti-backflow ribs) 291 that are integrally molded into the bush 25 can be formed at any position on the front side of the blocking section of the bush 25, and their thickness and width can also be freely molded, so that vertical ribs (anti-backflow ribs) 291 of the desired shape can be provided at any position on the bush 25. If one were to try to integrally mold the vertical rib (backflow prevention rib) 291 onto the fitting body 10 (upper connecting pipe 11), there would be constraints on the mold shape, the mold removal direction, the gate position, and the shrinkage of the resin, making it impossible to freely shape or position the vertical rib 291, and the locations where it can be installed would also be limited to a narrow range. In this regard, if the above-mentioned structure is used, taking into consideration avoiding positional interference with the first swirl vane 21b, as long as it is large enough to be formed on the front side of the horizontal pipe joint main body 26, there are few other restrictions, and the structure allows for greater freedom in the position and shape of the vertical rib (backflow prevention rib) 291.

[0054] If the intermediate pipe 15 is made of the above-mentioned fire-resistant material, when a fire breaks out on a floor below a certain floor slab 8, the heat of the fire causes the intermediate pipe 15 to expand radially inward, blocking the internal space of the joint body 10. This prevents flames, smoke, etc. from passing through the internal space of the intermediate pipe 15 and rising to floors above the floor slab 8. Therefore, the intermediate pipe 15 can exhibit fire resistance. In this case, since the lower end of the vertical rib (anti-backflow rib) 291 is positioned higher than the upper end of the intermediate pipe 15, the vertical rib (anti-backflow rib) 291 is prevented from interfering with the expansion of the intermediate pipe 15. The thermal expansion starting temperature of the thermally expandable graphite in resin composition (B), 240°C, is higher than the molding temperature (e.g., 140°C or higher and lower than 240°C) when producing pipe fitting 1. Therefore, expansion of the thermally expandable graphite can be prevented when producing pipe fitting 1.

[0055] When the intermediate tube 15 has a multi-layer structure, it is desirable that the strength of the multi-layer structure not be increased more than necessary so as not to inhibit the expansion of the thermally expandable graphite. For example, in the case of a multi-layer structure made of pipe material, it is desirable that the structure not exceed a double structure. Alternatively, the intermediate pipe 15 may be made of a resin that does not contain thermally expandable graphite, and a thermally expandable sheet may be provided on its outer periphery. The thermally expandable sheet contains the resin composition (A) or the resin composition (B). With the intermediate pipe 15 thus constructed, the thermally expandable sheet expands radially inward due to the heat of a fire, thereby sealing off the internal space of the coupling pipe 10. Therefore, the same effects as those of the above-described configuration can be achieved.

[0056] [First Modification (First Embodiment)] A first modified example of the first embodiment will be described below with reference to Figures 7 and 8. Figure 7 is a cross-sectional view showing the structure of a connection portion in a bush of a pipe joint according to the first modified example of the first embodiment, and Figure 8 is a perspective view of the bush as viewed from the tip side. In the horizontal pipe connecting portion according to the first modified example of the first embodiment, the horizontal pipe P3 is connected via a bush 25A instead of the bush 25, as shown in FIG.

[0057] The bushing 25A includes a horizontal pipe joint main body 261, and an annular second packing 27 and cover member 28 attached to one side (entrance side) of the horizontal pipe joint main body 261. The second packing 27 and cover member 28 are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0058] As shown in Figures 7 and 8, a horizontal pipe joint main body 261 according to a first modified example of the first embodiment has, for example, a backflow prevention portion (backflow prevention rib) 29A formed on the tip surface 26e of the blocking portion 26D. Furthermore, the tip surface 26e of the blocking portion 26D is disposed at a position along the inner peripheral wall of the upper connecting pipe 11 in a state in which the tip portion 14a of the connecting portion 14 and the corner portion 26g are in contact with each other.

[0059] Furthermore, at the opening 26d of the insertion hole 26b, a locking projection 26h is formed on the upper inner periphery side so as to project downward. When the end of the horizontal tube P3 is inserted into the insertion hole 26b, the locking protrusion 26h acts as a stopper for the horizontal tube P3 and determines the insertion depth of the horizontal tube P3 into the insertion hole 26b. There are no particular restrictions on the height or width of the locking protrusion 26h that protrudes inside the opening 26d, as long as it is high enough to abut against the tip of the horizontal tube P3 and prevent the horizontal tube P3 from entering.

[0060] Further, the small diameter protruding portion 26f is formed with a recess 26U that is recessed from the tip surface 26e of the closing portion 26D toward the second end 26B side, for example. When viewed from the first end 26A side (tip side), the upper side of the recess 26U is formed in an arc shape along the inner periphery, specifically the lower surface of the eave portion 194 described later, with a predetermined thickness between it and the upper surface of the small diameter protrusion 26f, and the lower side is formed in an arc shape positioned above the inner periphery of the opening 26d, with a thickness of the partition wall 26a between them, and the left and right sides are formed inside the inner surfaces of the vertical ribs 293 described later. The shape of the recess 26U when viewed from the first end 26A side (tip side) is not limited to the above and may be set arbitrarily.

[0061] A cap 26S is fitted into the recess 26U, thereby preventing wastewater from entering the recess 26U and from accumulating in the recess 26U. It is possible to arbitrarily determine whether or not to form the recess 26U in the small diameter protruding portion 26f, and whether or not to insert the cap 26S when the recess 26U is formed.

[0062] As shown in Figures 7 and 8, the backflow prevention portion (backflow prevention rib) 29A includes, for example, vertical ribs (backflow prevention ribs) 293 and eaves portions (backflow prevention ribs) 294 arranged above the vertical ribs.

[0063] The vertical rib (backflow prevention rib) 293 is disposed so as to protrude from the tip end surface 26e on the first end 26A side of the horizontal pipe joint main body 261 toward the axis of the joint main body 1 (upper connecting pipe 11) and extend in the axial direction (up and down direction) of the joint main body 1 (upper connecting pipe 11). Like the backflow prevention rib 29 of the first embodiment, the vertical rib is a rectangular plate-shaped vertical rib that protrudes to both the left and right sides of the opening 26d formed on the tip end surface 26e of the horizontal pipe joint main body 26A, sandwiching the opening 26d.

[0064] The eaves portion (backflow prevention rib) 294 protrudes from the tip surface 26e on the first end 26A side of the pipe fitting main body 261 toward the axis of the fitting main body 1 (upper connecting pipe 11), and, for example, the central portions on the left and right bulge upward, and specifically, the upper surface is formed in an arc shape that is the same shape as the upper surface of the small diameter protrusion 26f. The left and right ends of the eave portion 294 are connected to the upper ends of the left and right vertical ribs (backflow prevention ribs) 293, 293.

[0065] Here, the backflow prevention section (backflow prevention rib) 29A has vertical ribs 293 on both the left and right sides of the opening 26d of the horizontal pipe connection section 14, and has a canopy section 294 on the upper side of these, which catch the falling wastewater and prevent the wastewater from flowing back into the horizontal pipe P3 via the horizontal pipe connection section 14. In addition, when the above-mentioned wastewater becomes a swirling flow and falls from the upper connecting pipe 11, the vertical ribs 293, 293 and the eave portion 294 on both the left and right sides of the horizontal pipe connecting portion 14 receive the spiraling wastewater, preventing the wastewater from flowing back toward the horizontal pipe P3 via the horizontal pipe connecting portion 14.

[0066] The height of the vertical rib (backflow prevention rib) 293 is formed to be greater than the inner diameter of the opening 26d. Furthermore, when the closing portion 26D of the horizontal pipe joint main body 261 is fitted into the opening of the horizontal pipe connecting portion 14, the vertical rib 293 only needs to be able to pass through the opening of the horizontal pipe connecting portion 14. In order to obtain a sufficient backflow prevention effect, it is desirable that the height of the vertical rib 293 is high, but it should be high enough so that the vertical rib 293 does not interfere when fitting the horizontal pipe joint main body 26 into the opening of the horizontal pipe connection portion 14. The shape of the vertical rib (backflow prevention rib) 293 and its positional relationship with the horizontal pipe joint main body 261 are also shown in the perspective view of FIG. In addition, it is possible to arbitrarily set whether or not both ends of the eave portion 294 are connected to the upper parts of the left and right vertical ribs (backflow prevention ribs) 293, and the height of the vertical ribs (backflow prevention ribs) 293 may be set so that the upper parts of the left and right vertical ribs (backflow prevention ribs) 293 are not connected to the undersides of both ends of the eave portion (backflow prevention ribs) 294, forming a gap.

[0067] In addition, it is desirable to limit the protruding length of the vertical rib (backflow prevention rib) 293 and the eave portion (backflow prevention rib) 294, in other words, the width of the vertical rib 293 protruding from the inner surface of the upper connecting pipe 11 toward the central axis O, as described below. It is preferable that the vertical ribs (backflow prevention ribs) 293 and the eaves portions (backflow prevention ribs) 294 have a protruding height toward the central axis O that can avoid interference with wastewater flowing down from the riser pipe connection portion 13 side. The wastewater flowing down from the riser pipe connection portion 13 side here means wastewater flowing down from the first riser pipe P1 inserted into the riser pipe connection portion 13. For example, the overhang length that can avoid interference with wastewater flowing down from the vertical pipe connection portion 13 is the overhang length that, when viewed in vertical cross section as shown in Figure 1, does not protrude toward the central axis O beyond the inner peripheral end of the inward flange portion 21d formed at the lower end of the first bushing 21 or the inner peripheral end of the inward flange portion 22d at the lower end of the first gasket 22 arranged above it.

[0068] In this embodiment, the vertical rib (backflow prevention rib) 293 is in the shape of a vertically long rectangular plate, but the backflow prevention rib may also be in the shape of a curved plate, for example, a plate-shaped backflow prevention rib that curves along the outer peripheral surface of the blocking portion 26D. There is also no particular limit to the number of vertical ribs 293 provided; there may be one next to the opening 26d, or, for example, a single cylindrical backflow prevention rib that protrudes forward from the tip surface 26e of the blocking portion 26D.

[0069] When the vertical ribs (backflow prevention ribs) 293 are provided, they do not need to be parallel to each other, and may be formed in different directions, or may be formed in a direction other than toward the central axis O. Regardless of the direction in which the vertical ribs (backflow prevention ribs) 293 are oriented, it is sufficient that they are formed in a position that can block or suppress the flow of wastewater that attempts to flow back from the opening 26d into the interior of the horizontal pipe P3. The intermediate pipe 15 is preferably disposed below the lower end of the longitudinal rib (backflow prevention rib) 293.

[0070] Moreover, the eaves portion (backflow prevention rib) 294 does not have to be formed in an arc shape of the same diameter as the small-diameter protrusion 26f along the upper surface of the small-diameter protrusion 26f, but may be an arc shape of a smaller diameter than the small-diameter protrusion 26f, or may be a curved shape other than an arc. Also, the left and right sides may have different shapes. In addition, the eaves portion (backflow prevention rib) 294 may be configured so as to be not connected to either the left or right vertical rib (backflow prevention rib) 293, leaving a gap, or the eaves portion (backflow prevention rib) 294 and the vertical rib (backflow prevention rib) 293 may be connected only on the side that comes into contact with the most swirling wastewater.

[0071] Next, the operation of the pipe joint 1 according to the first modified example of the first embodiment will be described, focusing on the joint body 10.

[0072] In a building, wastewater from the upper floors flows into the joint body 10 and is guided downward through the first swirl vane 21b, the second swirl vane 30, and the third swirl vane 31. When the swirling flow of wastewater passes near the horizontal pipe connection part 14, the vertical ribs (backflow prevention ribs) 293 and the eave part (backflow prevention ribs) 294 provided on both the left and right sides of the opening 26d prevent or suppress the backflow of wastewater into the horizontal pipe P3.

[0073] According to the pipe fitting 1 of this embodiment, the vertical ribs (backflow prevention ribs) 293 and the eaves portions (backflow prevention ribs) 294 have a protruding height toward the central axis O that is sufficient to prevent interference with wastewater flowing downward from the vertical pipe connection portion 13, thereby preventing the wastewater flowing down from the vertical pipe connection portion 13 from directly hitting the vertical ribs 293 and the eaves portions 294. Therefore, the wastewater is less likely to directly hit the vertical ribs (backflow prevention ribs) 293 and the eaves portion (backflow prevention ribs) 294, and it is possible to suppress the generation of noise (abnormal noise) caused by the wastewater hitting the vertical ribs 293 and the eaves portion (backflow prevention ribs) 294. Therefore, it is possible to reduce the risk of complaints regarding noise.

[0074] According to the pipe fitting 1 of this embodiment, the vertical ribs (backflow prevention ribs) 293 and the eaves portion (backflow prevention ribs) 294 are integrally molded from resin together with the bushing 25A, thereby enabling efficient manufacture of the fitting body 10 (upper connecting pipe 11). Furthermore, even when the vertical ribs 293 and the eaves portion (backflow prevention ribs) 294 are provided on the bushing 25A, the bushing 25A can be easily manufactured.

[0075] The vertical ribs 293 and eaves 294 that are integrally molded with the bushing 25A can be formed at any position on the front side of the blocking section of the bushing 25A, and their thickness and width can also be freely molded, so that the vertical ribs 293 and eaves 294 of the desired shape can be provided at any position on the bushing 25A. If the vertical ribs 293 and the eaves portion 294 were to be integrally molded on the fitting main body 10 (upper connecting pipe 11), there would be constraints such as the mold shape, the mold removal direction, the gate position, and the shrinkage of the resin, which would prevent the vertical ribs 293 from being freely shaped or positioned, and the locations where they can be installed would be limited to a narrow range. However, with the configuration of the first modified example, there are fewer other constraints, resulting in a structure that allows for greater freedom in the position and shape of the vertical ribs 293 and the eaves portion 294.

[0076] Furthermore, since the lower end of the vertical rib (backflow prevention rib) 293 is positioned higher than the upper end of the intermediate pipe 15, even if a fire breaks out on a floor below a specified floor slab 8 and the heat causes the intermediate pipe 15 to expand, the vertical rib (backflow prevention rib) 293 can be prevented from becoming an obstacle. Other than that, it is the same as the first embodiment, so the same reference numerals are used and the description will be omitted.

[0077] [Second Modification (First Embodiment)] A second modified example of the first embodiment will be described below with reference to Figures 9 and 10. Figure 9 is a cross-sectional view showing the structure of a connection portion in a bush of a pipe joint according to the second modified example of the first embodiment, and Figure 10 is a perspective view of the bush as viewed from the tip side. In the horizontal pipe connecting portion according to the second modified example of the first embodiment, the horizontal pipe P3 is connected via a bush 25B instead of the bush 25, as shown in FIG.

[0078] The bushing 25B includes a horizontal pipe joint main body 262, and an annular second packing 27 and cover member 28 attached to one side (entrance side) of the horizontal pipe joint main body 262. The second packing 27 and cover member 28 are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0079] As shown in Figures 9 and 10, a horizontal pipe joint main body 262 according to a second modified example of the first embodiment has, for example, a backflow prevention portion (backflow prevention rib) 29B formed on the tip surface 26e of the blocking portion 26D. Furthermore, the tip surface 26e of the blocking portion 26D is disposed at a position along the inner peripheral wall of the upper connecting pipe 11 in a state in which the tip portion 14a of the connecting portion 14 and the corner portion 26g are in contact with each other.

[0080] Further, the small diameter protruding portion 26f is formed with a recess 26U that is recessed from the tip surface 26e of the closing portion 26D toward the second end 26B side, for example. When viewed from the first end 26A side (tip side), the upper side of the recess 26U is formed in an arc shape along the inner periphery with a predetermined thickness apart from the upper surface of the small diameter protrusion 26f, the lower side is formed in an arc shape along the upper surface of the eave portion 196 described later, and the left and right sides are formed inside the inner surface of the vertical rib 295 described later. The shape of the recess 26U when viewed from the first end 26A side (tip side) is not limited to the above and may be set arbitrarily. A cap 26S is fitted into the recess 26U, thereby preventing wastewater from entering the recess 26U and from accumulating in the recess 26U. It is possible to arbitrarily determine whether or not to form the recess 26U in the small diameter protruding portion 26f, and whether or not to insert the cap 26S when the recess 26U is formed.

[0081] As shown in Figures 9 and 10, the backflow prevention portion (backflow prevention rib) 29B includes, for example, vertical ribs (backflow prevention ribs) 295 and eaves portions (backflow prevention ribs) 296 arranged above the vertical ribs.

[0082] The vertical rib (backflow prevention rib) 295 is disposed so as to protrude from the tip end surface 26e on the first end 26A side of the horizontal pipe joint main body 262 toward the axis of the joint main body 1 (upper connecting pipe 11) and extend in the axial direction (up and down direction) of the joint main body 1 (upper connecting pipe 11). Then, like the backflow prevention rib 29 of the first embodiment, the vertical rib is a rectangular plate-shaped vertical rib that protrudes to both the left and right sides of the opening 26d opened in the tip end surface 26e of the horizontal pipe joint main body 26A, sandwiching the opening 26d.

[0083] The eaves portion (backflow prevention rib) 296 protrudes from the tip surface 26e on the first end 26A side of the pipe fitting main body 262 toward the axis of the fitting main body 1 (upper connecting pipe 11), and, for example, the central portions on the left and right bulge upward, and specifically, the lower surface is formed along the inner surface of the opening 26d, and the upper surface is arc-shaped formed along the arc-shaped lower side of the recess 26U. The left and right ends of the eave portion 296 are connected to the upper ends of left and right vertical ribs (backflow prevention ribs) 295, 295.

[0084] In addition, the eaves portion (backflow prevention rib) 296 has a locking protrusion 297 formed at the tip portion located on the axial center side of the joint body 1 (upper connecting pipe 11) that protrudes downward (toward the opening 26d). When the end of the horizontal tube P3 is inserted into the insertion hole 26b, this locking protrusion 297 acts as a stopper for the horizontal tube P3 and determines the insertion depth of the horizontal tube P3 into the insertion hole 26b. There are no particular restrictions on the height or width of the locking protrusion 297 protruding inside the opening 26d as long as it is high enough to abut against the tip of the horizontal tube P3 and prevent the horizontal tube P3 from entering.

[0085] Here, the backflow prevention section (backflow prevention rib) 29B has vertical ribs 295 on both the left and right sides of the opening 26d of the horizontal pipe connection section 14, and has a canopy section 296 on the upper side of these, which catch the falling wastewater and prevent the wastewater from flowing back into the horizontal pipe P3 via the horizontal pipe connection section 14. In addition, when the above-mentioned wastewater becomes a swirling flow and falls from the upper connecting pipe 11, the vertical ribs 295, 295 on both the left and right sides of the horizontal pipe connecting portion 14 receive the spiraling wastewater, preventing the wastewater from flowing back toward the horizontal pipe P3 via the horizontal pipe connecting portion 14.

[0086] The height of the vertical rib (backflow prevention rib) 295 and the eaves portion 296 is formed to be greater than the inner diameter of the opening 26d. When the closing portion 26D of the horizontal pipe joint main body 262 is fitted into the opening of the horizontal pipe connecting portion 14, the vertical rib 295 and the eaves portion 296 only need to be able to pass through the opening of the horizontal pipe connecting portion 14. In order to fully achieve the backflow prevention effect, it is desirable that the height of the vertical ribs 295 and the eaves portion 296 be high, but the height should be such that the vertical ribs 295 and the eaves portion 296 do not interfere with fitting the horizontal pipe joint main body 26 into the opening of the horizontal pipe connection portion 14. The shape of the vertical rib (backflow prevention rib) 295 and its positional relationship with the horizontal pipe joint main body 262 are also shown in the perspective view of FIG. In addition, it is possible to arbitrarily set whether or not both ends of the eave portion 296 are connected to the upper parts of the left and right vertical ribs (backflow prevention ribs) 295, and the height of the vertical ribs (backflow prevention ribs) 295 may be set so that the upper parts of the left and right vertical ribs (backflow prevention ribs) 295 are not connected to the undersides of both ends of the eave portion (backflow prevention ribs) 296, forming a gap.

[0087] In addition, it is desirable to limit the protruding length of the vertical rib (backflow prevention rib) 295 and the eave portion (backflow prevention rib) 296, in other words, the width of the vertical rib 295 protruding from the inner surface of the upper connecting pipe 11 toward the central axis O, as described below. It is preferable that the vertical ribs (backflow prevention ribs) 295 and the eaves portions (backflow prevention ribs) 296 have a protruding height toward the central axis O that can avoid interference with wastewater flowing down from the riser pipe connection portion 13 side. The wastewater flowing down from the riser pipe connection portion 13 side here means wastewater flowing down from the first riser pipe P1 inserted into the riser pipe connection portion 13. For example, the overhang length that can avoid interference with wastewater flowing down from the vertical pipe connection portion 13 is the overhang length that, when viewed in vertical cross section as shown in Figure 1, does not protrude toward the central axis O beyond the inner peripheral end of the inward flange portion 21d formed at the lower end of the first bushing 21 or the inner peripheral end of the inward flange portion 22d at the lower end of the first gasket 22 arranged above it.

[0088] In this embodiment, the vertical rib (backflow prevention rib) 295 is in the shape of a vertically long rectangular plate, but the backflow prevention rib may also be in the shape of a curved plate, for example, a plate-shaped backflow prevention rib that curves along the outer peripheral surface of the blocking portion 26D. There is also no particular limit to the number of vertical ribs 295 provided; there may be one next to the opening 26d, or, for example, a single cylindrical backflow prevention rib that protrudes forward from the tip surface 26e of the blocking portion 26D.

[0089] When the vertical ribs (backflow prevention ribs) 295 are provided, they do not need to be parallel to each other, and may be formed in different directions, or may be formed in a direction other than toward the central axis O. Regardless of the direction in which the vertical ribs (backflow prevention ribs) 295 are oriented, it is sufficient that they are formed in a position that can block or suppress the flow of wastewater that attempts to flow back from the opening 26d into the interior of the horizontal pipe P3. The intermediate pipe 15 is preferably disposed below the lower end of the longitudinal rib (backflow prevention rib) 295 .

[0090] The eaves portion (backflow prevention rib) 296 does not have to have an arc-shaped lower surface formed along the inner circumferential surface of the opening 26d, but may have an arc-shaped lower surface with a larger diameter than the small-diameter protrusion 26f, or may have a curved shape other than an arc. Also, the left and right sides may have different shapes. In addition, the eaves portion (backflow prevention rib) 296 may be configured so as to be not connected to either the left or right vertical rib (backflow prevention rib) 295, leaving a gap, or the eaves portion (backflow prevention rib) 296 and the vertical rib (backflow prevention rib) 295 may be connected only on the side that comes into contact with the most swirling wastewater.

[0091] Next, the operation of the pipe joint 1 according to the second modified example of the first embodiment will be described, focusing on the joint body 10. In a building, wastewater from the upper floors flows into the joint body 10 and is guided downward through the first swirl vane 21b, the second swirl vane 30, and the third swirl vane 31. When the swirling flow of wastewater passes near the horizontal pipe connection part 14, the vertical ribs (backflow prevention ribs) 295 and the eave part (backflow prevention ribs) 296 provided on both the left and right sides of the opening 26d prevent or suppress the backflow of wastewater into the horizontal pipe P3.

[0092] According to the pipe fitting 1 of this embodiment, the vertical ribs 295 and the eaves portion (backflow prevention ribs) 296 have a protruding height toward the central axis O that is sufficient to prevent interference with wastewater flowing downward from the vertical pipe connection portion 13, thereby preventing the wastewater flowing down from the vertical pipe connection portion 13 from directly hitting the vertical ribs 295 and the eaves portion 296. Therefore, the wastewater is less likely to directly hit the vertical ribs (backflow prevention ribs) 293 and the eaves portion (backflow prevention ribs) 296, and it is possible to suppress the generation of noise (abnormal noise) caused by the wastewater hitting the vertical ribs 295 and the eaves portion (backflow prevention ribs) 296. Therefore, it is possible to reduce the risk of complaints regarding noise.

[0093] According to the pipe fitting 1 of this embodiment, the vertical ribs (backflow prevention ribs) 295 and the eaves portion (backflow prevention ribs) 296 are formed as an integral resin molding together with the bushing 25B, thereby enabling efficient manufacture of the fitting body 10 (upper connecting pipe 11). Furthermore, even when the vertical ribs 295 and the eaves portion (backflow prevention ribs) 296 are provided on the bushing 25B, the bushing 25B can be easily manufactured.

[0094] The vertical ribs 295 and eaves 296 that are integrally molded with the bushing 25B can be formed at any position on the front side of the blocking portion of the bushing 25B, and their thickness and width can also be freely molded, so that the vertical ribs 293 and eaves 296 of the desired shape can be provided at any position on the bushing 25B. If the vertical ribs 295 and the eaves portion 296 were to be integrally molded on the fitting main body 10 (upper connecting pipe 11), there would be constraints such as the mold shape, the mold removal direction, the gate position, and the shrinkage of the resin, which would prevent the vertical ribs 295 from being freely shaped or positioned, and the locations where they can be installed would be limited to a narrow range. However, with the configuration of the first modified example, there are fewer other constraints, resulting in a structure that allows for greater freedom in the position and shape of the vertical ribs 295 and the eaves portion 296.

[0095] Furthermore, since the lower end of the vertical rib (backflow prevention rib) 295 is positioned higher than the upper end of the intermediate pipe 15, even if a fire breaks out on a floor below a specified floor slab 8 and the heat causes the intermediate pipe 15 to expand, the vertical rib (backflow prevention rib) 295 can be prevented from causing any obstruction. Other than that, it is the same as the first embodiment, so the same reference numerals are used and the description will be omitted.

[0096] Second Embodiment The pipe joint of the present invention can be modified in various ways in terms of its configuration, as in the various embodiments described below. For example, as shown in the pipe fitting 40 in Figure 11, the present invention can be applied to a multi-stage pipe fitting in which one or more horizontal pipe connecting portions 14 having the same configuration as the horizontal pipe connecting portion 14 provided on the upper connecting pipe 11 are provided between the upper connecting pipe 11 and the intermediate pipe 15. In the second embodiment, an extension pipe 37 for addition and a joint pipe main body 38 are provided below the upper connecting pipe 11, and a plurality of horizontal pipe joint portions 14 are formed on the outer periphery of the joint pipe main body 38. An intermediate pipe 15 and a lower connecting pipe 12 are joined to the lower end of the joint pipe main body 38. The joint pipe main body 38 in Figure 11 is formed with a pair of horizontal pipe joint portions 14 facing each other on the left and right in the vertical cross section shown in Figure 11.

[0097] A bushing 45 including a horizontal pipe joint main body 41, a third packing 42, and a cover member 43 is connected to the horizontal pipe connecting part 14 provided on the upper connecting pipe 11 shown in Figure 11. The horizontal pipe joint main body 41 is formed in a single cylinder and has a shape that can be fitted into the opening of the horizontal pipe connecting part 14, and the peripheral wall of the horizontal pipe joint main body 41 has the same thickness. For this reason, the inner diameter of the insertion hole 41b formed in the horizontal pipe joint main body 41 is larger than the inner diameter of the insertion hole 26b of the first embodiment, and a horizontal pipe P4 having an outer diameter larger than the horizontal pipe P3 of the first embodiment is connected to this insertion hole 41b.

[0098] The horizontal pipe joint main body 41 has a small diameter protrusion 41f formed on the outer periphery of the tip end thereof, so that the first end 41A side of the horizontal pipe joint main body 41 can be fitted into the opening of the horizontal pipe connecting portion 14 of the upper connecting pipe 11, which is the same structure as the horizontal pipe joint main body 26 of the first embodiment. A large diameter portion 41E is provided on the second end 41B side of the horizontal pipe joint main body 41, and a cover member 43 that can be fitted onto this large diameter portion 41E is provided, preventing the third gasket 42 from coming loose, which is also the same structure as the horizontal pipe joint main body 26 of the first embodiment. Furthermore, at an opening 41d of a tip surface 41e on the first end side 41A side of the insertion hole 41b, a locking protrusion 41h is formed on the inner upper periphery side so as to protrude downward. This locking projection 41h serves as a stopper for the horizontal tube P4 when the end of the horizontal tube P4 is inserted into the insertion hole 41b, and the same applies to the structure that determines the insertion depth of the horizontal tube P4 into the insertion hole 41b.

[0099] In the structure of the second embodiment, a bushing 45 having a horizontal pipe joint main body 41, a third packing 42, and a cover member 43 is connected to each of the pair of left and right horizontal pipe connecting portions 14 of the joint pipe main body 38. As shown in Figure 11, a bushing 45 equipped with a backflow prevention rib (backflow prevention portion) 50 is fitted into the horizontal pipe connection portion 14 provided on the left side of the joint pipe main body 38, on the side opposite the horizontal pipe connection portion 14 provided on the upper connecting pipe 11.

[0100] This bushing 45 differs from the bushing 45 provided on the upper connecting pipe 11 described above only in that it is oriented 180° in the opposite direction and that it is provided with a backflow prevention rib 50 . In the structure of the pipe joint 40 shown in FIG. 11, a backflow prevention rib 50 is provided on the tip end surface of the horizontal pipe joint main body 41, as also shown in FIG. The backflow prevention rib 50 of the second embodiment protrudes from the tip end surface of the horizontal pipe joint main body 41 and, like the backflow prevention rib 29 of the first embodiment, has rectangular plate-shaped vertical ribs 50A protruding on both the left and right sides of an opening 41d opened in the tip end surface of the horizontal pipe joint main body 41. The backflow prevention rib 50 also has a visor portion 50B made of a curved plate that connects the upper ends of the left and right vertical ribs 50A, 50A.

[0101] In the joint pipe 40 shown in Fig. 11, horizontal pipe connecting portions 14 are provided on the upper right side and below it in the vertical cross section shown in Fig. 11, and the horizontal pipe connecting portion 14 is provided in a position opposite the horizontal pipe connecting portion 14 on the lower right side across the central axis O. For this reason, bushings 45 of the same structure are provided on the upper right side and below it in the vertical cross section shown in Fig. 11, and a bushing 45 with a backflow prevention rib 50 is provided on the lower left side of the joint pipe 40 in a position opposite the bushing 45 on the lower right side across the central axis O. In other words, in the longitudinal cross section shown in Figure 11, the bushing 45 on the lower left side is spaced apart from the bushing 45 on the upper right side along the axial direction of the joint body 10, and is formed in positions that face each other alternately across the central axis O of the joint body 10.

[0102] A horizontal pipe P5 is connected to the bushing 45 on the lower right side in FIG. 11, and a horizontal pipe P6 is connected to the bushing 45 on the lower left side. At the opening 41d of the bushing 45 on the lower right side, a locking protrusion 41h is formed so as to protrude downward from the upper inner periphery. This locking protrusion 41h acts as a stopper for the horizontal pipe P5 when the end of the horizontal pipe P5 is inserted into the insertion hole 41b, and determines the insertion depth of the horizontal pipe P5 into the insertion hole 41b. At the opening 41d of the bushing 45 on the lower left side, a locking protrusion 41h is formed so as to protrude downward from the upper inner periphery. This locking protrusion 41h acts as a stopper for the horizontal pipe P6 when the end of the horizontal pipe P6 is inserted into the insertion hole 41b, and determines the insertion depth of the horizontal pipe P6 into the insertion hole 41b.

[0103] In the pipe fitting 40 having the structure shown in Fig. 11, when wastewater flows into the upper connecting pipe 11 from the horizontal pipe P4 on the upper right side, the wastewater may fall as shown by the arrow S in Fig. 11. Here, the horizontal pipe connecting part 14, to which the horizontal pipe P5 is connected, is provided below the direction of the arrow S, so in some cases, some of the wastewater falling in the direction of the arrow S may flow back into the horizontal pipe P5 via the horizontal pipe connecting part 14. Here, the backflow prevention rib 50 has vertical ribs 50A on both the left and right sides of the opening 41d of the horizontal pipe connection portion 14, and has a canopy portion 50B on the upper side of these, which catch the falling wastewater and prevent the wastewater from flowing back into the horizontal pipe P5 via the horizontal pipe connection portion 14. In addition, when the above-mentioned wastewater becomes a swirling flow and falls from the upper connecting pipe 11, the vertical ribs 50A, 50A on both the left and right sides of the horizontal pipe connecting portion 14 receive the wastewater that has become a spiral flow, preventing the wastewater from flowing back toward the horizontal pipe P5 via the horizontal pipe connecting portion 14.

[0104] Figure 13 shows an example of the arrangement of vertical ribs that would be expected if bushings 45 were fitted into the horizontal pipe connecting portions 14A and 14B to provide backflow prevention ribs in a structure in which horizontal pipe connecting portions 14A and 14B are provided at 90° intervals around the circumferential direction of the fitting body 10. As shown in Figure 13, a structure may be adopted in which one backflow prevention rib (backflow prevention portion) 55 is provided for each of the horizontal pipe connecting portions 14A, 14B. Also, as shown in Figure 13, the backflow prevention rib 55 may be arranged so that it extends toward the central axis of the fitting body 10, at a substantially right angle to the inner peripheral surface of the fitting body 10.

[0105] Assuming that the flow direction of the swirling flow inside the fitting body 10 is the direction indicated by arrow R as shown in Figure 13, a structure in which a backflow prevention rib 55 is provided upstream of the horizontal pipe connecting part 14A in the flow direction R of the swirling flow is preferable. A structure in which a backflow prevention rib 55 is provided upstream of the flow direction R of the swirling flow is preferable for the horizontal pipe connecting part 14B. By adopting this structure, one backflow prevention rib 55 can provide a backflow prevention effect for the horizontal pipe connection portion 14A, and another backflow prevention rib 55 can provide a backflow prevention effect for the horizontal pipe connection portion 14B. As described in the structure shown in Figures 1 and 11, components such as swirl vanes are provided inside the joint body 10, so a structure in which one backflow prevention rib is provided for one horizontal pipe connection section reduces interference with other components and is easier to implement.

[0106] In the embodiments described so far, a structure in which backflow prevention ribs are provided on the horizontal pipe joint main body 26, 41 has been exemplified, but a structure in which a vertical rib is provided separately on the upper connecting pipe 11 side in addition to the backflow prevention ribs 26, 41 described so far may also be adopted. Furthermore, if the formation positions of the vertical ribs shown in Figure 13 are considered to be the formation positions of the aforementioned backflow prevention ribs, it is possible to obtain the same backflow prevention effect as in the above-mentioned embodiment by applying a structure in which backflow prevention ribs are provided only on the horizontal pipe connection parts located upstream of the swirling flow, rather than providing backflow prevention ribs on all of the horizontal pipe connection parts provided circumferentially on the upper connecting pipe 11.

[0107] For this reason, for example, in the structure shown in Figure 13, when a branch plug member 56 that only closes the horizontal pipe connection portion 14A is attached to the horizontal pipe connection portion 14A, a structure may be adopted in which a backflow prevention rib 55 is provided only on the right side of this branch plug member 56 as shown in Figure 13, and no backflow prevention rib is provided on the side of the horizontal pipe connection portion 14B that connects the horizontal pipe. In this structure, the backflow prevention rib 55 formed on the branch plug member 56 is positioned upstream of the horizontal pipe connection part 14B that connects the horizontal pipes, assuming that the direction of the swirling flow is R, so that the same backflow prevention effect as the above-mentioned configuration can be obtained.

[0108] Although each embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration of the present invention is not limited to these embodiments, and the present invention also includes changes, combinations, deletions, etc. of the configuration within the scope that does not deviate from the gist of the present invention. For example, in the previous embodiment, a rectangular plate-shaped backflow prevention rib was used, but it may also be a curved plate shaped like a cylindrical pipe with a portion of the peripheral wall cut away. Also, a structure may be adopted in which a backflow prevention rib consisting of a single cylindrical annular wall is attached to the front side of the horizontal pipe joint main body 26, 41 or branch plug member 56. Furthermore, although the horizontal pipe joint main bodies 26, 41 in the previous embodiments are provided with vertical ribs and eaves portions as backflow prevention ribs, they may be provided with only either the vertical ribs or the eaves portions. [Explanation of symbols]

[0109] 10... Joint body, 11... Upper connecting pipe, 12... Lower connecting pipe, 13... Vertical pipe connecting portion, 14...Horizontal pipe connection portion, 15...Intermediate pipe, 21b...First swirl vane, 25, 25A, 25B...Bush, 26, 261, 262...Horizontal pipe joint main body portion, 26b...Insertion hole, 26D...Blocking portion, 26e...Tip surface, 26f...Small diameter protrusion portion, 26h, 297...Latching protrusion, 29, 29A, 29B...Backflow prevention portion (backflow prevention rib), 291, 293, 295...Vertical rib (backflow prevention rib), 294, 296...Eave portion (backflow prevention rib) 30... second swirl blade, 31... third swirl blade, 40... joint body, 41... horizontal pipe joint body portion, 41b... insertion hole, 41d... opening, 41e...tip surface, 41f...small diameter protrusion, 41h...engaging protrusion, 45...bush, 50, 55... Backflow prevention part (backflow prevention rib), P1, P2, P3, P4, P5, P6...horizontal pipe, C1, C2...center axis, O...center axis line.

Claims

1. a joint body formed in a cylindrical shape; a horizontal pipe connection portion having an end connected to a side surface of the joint body and an opening formed in the end communicating with the inside of the joint body; a bushing fitted to the horizontal pipe connection portion; a backflow prevention portion formed on the bush and protruding from an inner peripheral surface of the joint body toward the inside of the joint body, A small diameter protrusion is formed on the tip side of the bush, and the bush is positioned by fitting the small diameter protrusion into the horizontal pipe connection portion.

2. A pipe fitting as described in claim 1, wherein a through hole for inserting a horizontal pipe is formed in the bush, and a locking protrusion for regulating the insertion depth of the horizontal pipe is formed in the opening of the through hole located on the tip side of the bush.

3. 3. A pipe joint according to claim 1, wherein the backflow prevention portion is a backflow prevention rib that protrudes from the inner peripheral surface of the joint body toward the axial center of the joint body and extends in the axial direction of the joint body.

4. 4. A pipe joint according to claim 1, wherein a plurality of the horizontal pipe connecting portions are formed in the circumferential direction of the joint body.

5. 5. A pipe fitting according to claim 1, wherein the horizontal pipe connection portions are formed at positions spaced apart along the axial direction of the fitting body and alternately opposed to each other across the axis of the fitting body, and the backflow prevention portion is provided in the horizontal pipe connection portion that is located lower than the pair of horizontal pipe connection portions that are opposed to each other across the axis.

6. 6. A pipe joint according to claim 1, wherein the joint body is provided with swirl vanes for swirling the flow of water passing through the joint body.

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