Rainwater drainage fitting, rainwater drainage system, and building

Abstract

To provide a rainwater drainage fitting capable of maintaining the strength of the joint while maintaining a high displacement, and a rainwater drainage system.SOLUTION: The rainwater drainage fitting includes: a first end 11 where rainwater flows in; a second end 12 where rainwater flows out; and a reduced portion 28 having a water passage area smaller than the water passage area of the first end 11 between the first end 11 and the second end 12. The first end 11 and the second end 12 are bolted to another member.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a stormwater drainage joint, a stormwater drainage system, and a building. [Background technology]

[0002] The gutter system of Patent Document 1 is a large-scale gutter system that generates a siphon effect by including a diameter-reducing section. It has been known that siphoning occurs in conventional gutter systems that have a narrowed section in the downspout. In this gutter system, rainwater (water) accumulates in the narrowed section. Then, the siphoning occurs due to gravity acting on the accumulated rainwater. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-124005 Summary of the Invention [Problem to be solved by the invention]

[0004] However, it is known that in gutter systems with a narrowed diameter section, the flow velocity increases at the narrowed diameter section when draining water. In particular, in large gutter systems with a large drainage volume, such as those described in Patent Document 1, the increase in flow velocity at the narrowed diameter section becomes significant, causing increased vibration of the drain pipe. In this case, stress tends to concentrate at the connection between the drain pipe and the narrowed diameter section, which could lead to water leakage during use. Water leakage is a major problem, especially when the rainwater drainage system is installed indoors.

[0005] The present invention has been made in consideration of these problems, and aims to provide a rainwater drainage joint, a rainwater drainage system, and a building that can maintain the strength of the connection while maintaining a high drainage volume. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention proposes the following means.

[0007] (1) The rainwater drainage joint of the present invention has a first end through which rainwater flows in, a second end through which rainwater flows out, and a reduced section between the first end and the second end, which has a water flow area smaller than the water flow area of ​​the first end, and the first end and the second end are bolted to another member. In large-scale stormwater drainage systems with high discharge volumes, the flow velocity increases significantly at the contraction section, causing significant vibration of the drain pipe. In this case, if the first and second ends are bolted to the piping as described above, water leakage can be prevented even if stress is concentrated at the connection between the drain pipe and the contraction section. This allows the strength of the connection to be maintained while maintaining a high discharge volume. (2) The rainwater drainage joint of the present invention has a first end through which rainwater flows in, a second end through which the rainwater flows out, and a reduced section between the first end and the second end, the reduced section having a water flow area smaller than the water flow area of ​​the first end, and the first end and the second end may be joined to another member by electrical fusion. If the first end and the second end are electrically fused to the pipe, water leakage can be prevented even if stress is concentrated at the connection between the pipe and the contraction section. Therefore, the strength of the connection can be maintained while maintaining a high discharge volume. Furthermore, if the first end and the second end are electrically fused to the pipe, the space required for installation is small. Therefore, it is easy to secure installation space, especially for indoor piping where installation space is limited. (3) In the rainwater drainage joint of the present invention, the reduced portion may have a protrusion extending toward the center of the pipe axis. With this configuration, rainwater with a reduced flow rate temporarily accumulates in the flow path between the pipe and the upper edge of each protrusion, making it difficult for air to enter the rainwater flowing into the rainwater drainage fitting, ensuring the siphon effect. Moreover, because the rainwater has already been rectified after passing through each protrusion, it drains smoothly without swirling. This allows for a higher drainage volume to be maintained. (4) The rainwater drainage joint of the present invention may be fire-resistant. With this configuration, the rainwater drainage joints can easily penetrate the fire compartment (slab), and the rainwater drainage system can be made highly fire-resistant. (5) The rainwater drainage system of the present invention comprises an inlet through which rainwater flows, a pipe connected to the inlet, and a rainwater drainage fitting connected to the pipe and described in (1) or (2) above. (6) The rainwater drainage system of the present invention may further include a branch pipe and a confluence where the branch pipe and the pipe converge, the confluence being provided downstream of the rainwater drainage joint, and the vertical length from the lower end of the rainwater drainage joint to the confluence being 1000 mm or more. (7) The building of the present invention is equipped with the rainwater drainage system described in (5) above. [Effects of the Invention]

[0008] The present invention can provide a rainwater drainage joint, a rainwater drainage system, and a building that can maintain the strength of the connection while maintaining a high drainage volume. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a building in which the storm water drainage system of the present invention is installed. [Figure 2] 1 is a schematic diagram showing an example of a stormwater drainage system of the present invention. [Figure 3] FIG. 2 is an enlarged cross-sectional view of a rainwater drainage joint provided in the rainwater drainage system of the present invention. [Figure 4] FIG. 10 is an enlarged cross-sectional view of a rainwater drainage joint according to a second embodiment. [Figure 5] FIG. 10 is an enlarged cross-sectional view of a rainwater drainage joint according to a third embodiment. [Figure 6] FIG. 10 is an enlarged cross-sectional view of a rainwater drainage joint according to a fourth embodiment. [Figure 7] FIG. 10 is an enlarged cross-sectional view of a rainwater drainage joint according to a fifth embodiment. [Figure 8] FIG. 2 is an enlarged view of the fixing portion of the first embodiment of the rainwater drainage joint of the present invention. [Figure 9] FIG. 4 is an enlarged view of the fixing portion of a second embodiment of the rainwater drainage joint of the present invention. [Figure 10] FIG. 4 is a cross-sectional view of the fixing portion of a second embodiment of the rainwater drainage joint of the present invention. [Figure 11A] FIG. 10 is an enlarged view of the unconnected state of the fixing part of the third embodiment of the rainwater drainage joint of the present invention. [Figure 11B] FIG. 10 is an enlarged view of the connection state of the fixing portion of the third embodiment of the rainwater drainage joint of the present invention. [Figure 12] FIG. 10 is an enlarged view of a fourth embodiment of the fixing portion of the rainwater drainage joint of the present invention. [Figure 13] FIG. 10 is an enlarged view of a fifth embodiment of the fixing portion of the rainwater drainage joint of the present invention. [Figure 14] FIG. 10 is an enlarged view of a sixth embodiment of the fixing portion of the rainwater drainage joint of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a rainwater drainage system 100 and a rainwater drainage joint 1 according to an embodiment of the present invention will be described with reference to FIGS.

[0011] As shown in FIG. 1, the storm water drainage system 100 is installed in a building 200 . 1 is a three-story building, with floors 210 provided between the first and second floors and between the second and third floors. However, the building 200 does not have to be three stories tall.

[0012] The stormwater drainage system 100 moves rainwater that falls on the building 200 to the vicinity of the ground and drains it into sewer pipes. In this embodiment, the building 200 is provided with two stormwater drainage systems 100 near opposite sides. The building 200 may also be provided with only one stormwater drainage system 100.

[0013] The inlet 220 is provided to drain rainwater that has fallen on the building 200 into the stormwater drainage system 100. In the illustrated example, the inlet 220 is provided on the roof of the building 200, but the location of the inlet 220 is not limited thereto, and the inlet 220 may be provided somewhere other than the roof, or may be provided both on the roof and somewhere other than the roof.

[0014] As shown in FIG. 1 , the drain outlet 230 is connected to the most downstream side of the stormwater drainage system 100 and drains the rainwater collected via the inlet 220 into a sewer pipe. The drain outlet 230 opens, for example, into a manhole buried underground. The drain outlet 230 may also open vertically downward within the manhole. For example, the drain outlet 230 may open vertically downward within the manhole by connecting an elbow to a straight pipe extending horizontally. The elbow used in such a case may be, for example, a DL elbow (90° elbow), a 45° elbow, a large curved elbow, or the like.

[0015] (Rainwater drainage system 100) FIG. 2 shows a storm water drainage system 100 according to this embodiment. 2, the rainwater drainage system 100 in this embodiment has a horizontal pipe 110 and a vertical pipe 120. The rainwater drainage system 100 is installed inside a building 200. Furthermore, the stormwater drainage system 100 may be configured with only the standpipe 120. The rainwater drainage system 100 may have a drainage structure via a rainwater drainage pit used on a flat roof or the like. The drainage structure via a rainwater drainage pit used on a flat roof or the like may be, for example, a structure in which a standpipe and a joint are connected directly below a square pit. The rainwater drainage system 100 may be placed outdoors of the building 200.

[0016] In the stormwater drainage system 100 of this embodiment, the inlet 220 is connected to the horizontal lead pipe 110 via a bend 6 (elbow). The horizontal lead pipe 110 is connected to the upright pipe 120 via a bend 6 (elbow). A junction pipe 111 (horizontal lead pipe 110) may be connected to the upright pipe 120. The riser pipes 120 are arranged downward from each of the multiple inlets 220. The riser pipes 120 are arranged along a substantially vertical direction (which can also be said to be an up-down direction). The upper end of the riser pipe 120 is connected to, for example, the inlet 220. The lower end of the riser pipe 120 is connected to, for example, the horizontal pipe 110. The lower end of the riser pipe 120 is located, for example, in a pipe space. The lower end of the riser pipe 120 is located, for example, above a panel (ceiling panel). The lower end of the riser pipe 120 is connected to the horizontal pipe 110 via, for example, an elbow, a tee, or the like.

[0017] The standpipe 120 is arranged in the vertical direction. The standpipe 120 may be offset at intermediate floors and include a horizontal section. The upper end of the standpipe 120 is connected to the horizontal section 110. Rainwater that passes through the standpipe 120 is discharged to the outside of the building 200 through a drain outlet 230 (not shown). The rainwater discharged to the outside of the building 200 is discharged into a sewer pipe through a stormwater manhole (not shown). A rainwater storage tank (not shown) may be connected to the drain outlet 230. The riser 120 has a plurality of pipes 2. There is no limitation on the method for connecting the pipes 2 to each other. The pipes 2 may be metal pipes.

[0018] The horizontal pull pipe 110 is arranged along the horizontal direction and is connected to the lower end or upper end of the piping 2 of the vertical pipe 120. The horizontal pull pipe 110 is located in the pipe space. The horizontal pull pipe 110 is arranged so that the end on the vertical pipe 120 side is horizontal with or lower than the opposite end. The horizontal drawing pipe 110 has a pipe 2. The horizontal drawing pipe 110 may have one pipe 2 or may have a plurality of pipes 2. There is no limitation on the method for connecting the pipes 2 to each other.

[0019] The standpipe 120 has a rainwater drainage joint 1. Details of the rainwater drainage joint 1 will be described later. The standpipe 120 may have one or more rainwater drainage joints 1. The rainwater drainage joints 1 are preferably installed at equal intervals relative to the standpipe 120. The rainwater drainage joints 1 are preferably installed one every 15 m, and more preferably one every 5 m. It is preferable that at least one rainwater drainage joint 1 is installed on each floor. In this case, since the floor height varies depending on the building, the installation interval of the rainwater drainage joints 1 can be set appropriately taking into account the floor height of the building 200 in which the rainwater drainage system 100 is installed.

[0020] There are no particular limitations on the SDR value of the pipe 2. The SDR value is the ratio of the outer diameter D to the wall thickness T, and SDR value=outer diameter D / wall thickness T. The outer diameter of the pipe 2 may be, for example, 60.0 mm to 216.0 mm. In particular, the outer diameter of the pipe 2 is preferably 76.0 mm to 216.0 mm, for example, downstream where the flow rate is large. The pipes 2 in the vertical pipe 120 and the horizontal pipe 110 may have the same inner diameter, or may have different inner diameters. For example, the inner diameter of the pipe 2 may be smaller or larger from the upstream side to the downstream side in the drainage direction. For example, in the vertical pipe 120, the inner diameter of the pipe 2 may be smaller from the upstream side to the downstream side in the drainage direction. Furthermore, for example, in the horizontal pipe 110, the inner diameter of the pipe 2 may be larger from the upstream side to the downstream side in the drainage direction.

[0021] (Rainwater drainage joint 1) The rainwater drainage joint 1 has a first end 11 through which rainwater flows in, a second end 12 through which rainwater flows out, and a reduced section 28 having a water flow area smaller than that of the first end 11. The reduction unit 28 is configured, for example, as follows.

[0022] (First embodiment) As shown in FIG. 3, the joint with protrusions (rainwater drainage joint) 1 of the first embodiment has a joint body 10 and a plurality of protrusions 20 (fins). The fitting body 10 is a cylindrical pipe having a central axis O1 along the vertical direction, and has an inlet side joint portion (first end) 11 formed at the upper end, an outlet side joint portion (second end) 12 formed at the lower end, and a straight pipe portion 13 formed between them. The inlet side joint 11 has a ring shape, is coaxially connected to the lower end of the upper pipe (pipe) 2a, and is fixed at the fixing part 3. The details of the fixing part 3 will be described later. The inner peripheral surface of the inlet side joint 11 is watertightly connected to the lower end of the upper pipe 2a via a sealing material (not shown). The outlet-side joint 12 also has a ring shape and is fixed coaxially to the upper end of the lower pipe (pipe) 2b. Details of the fixing part 3 will be described later. The inner circumferential surface of the outlet-side joint 12 is watertightly connected to the upper end of the lower pipe 2b via a sealing material (not shown).

[0023] The straight pipe section 13 is a cylindrical pipe located between the inlet joint 11 and the outlet joint 12, and is coaxial with the inlet joint 11 and the outlet joint 12. The nominal diameters of the upper pipe 2a, the protruding joint 1, and the lower pipe 2b may be the same. In this case, the external appearance is the same, resulting in an aesthetically pleasing stormwater drainage system 100. The inner diameter of the straight pipe portion 13 is also equal to the inner diameter of the upper pipe 2a and the inner diameter of the lower pipe 2b. Therefore, the flow path extending vertically through the interiors of the upper pipe 2a, the protruding fitting 1, and the lower pipe 2b forms a cylindrical internal space having the same inner diameter at each position in the vertical direction, except for the portion where the protrusion 20 is arranged. In other words, it is preferable that the flow path from the upper pipe 2a to the lower pipe 2b via the protruding fitting 1 is connected smoothly and without steps at both the connection point between the upper pipe 2a and the protruding fitting 1 and the connection point between the protruding fitting 1 and the lower pipe 2b.

[0024] In this embodiment, the reduced section 28 is constituted by protrusions 20. The protrusions 20 are multiple blades formed integrally with the inner wall surface 13a of the straight pipe section 13 of the protrusion-equipped joint 1. In this embodiment, four protrusions 20 are arranged at equal angular intervals (90° intervals) in the circumferential direction around the central axis O1 of the straight pipe section 13. The number of protrusions 20 is not limited to four, and may be two, three, five or more, or even ten or more. Each protrusion 20 has the same shape and dimensions, and is also positioned in the same position along the pipe axis direction.

[0025] That is, as shown in FIG. 3 , all of the protrusions 20 are isosceles triangles in longitudinal cross section or side view, with their bases integrally connected to the inner wall surface 13a of the straight pipe section 13. Therefore, each protrusion 20 is formed to protrude from the inner wall surface 13a toward the pipe axis (center axis). One of the equal sides of the isosceles triangle that form these protrusions 20, the straight upper side 21, is located upstream (vertically upward) in the flow path, and the other straight lower side 22 is located downstream (vertically downward) in the flow path. The upper and lower sides 21 and 22 are connected at a connection point 23. The most upstream side of the upper side 21 is defined as the starting point B of the contracted section 28. The shape of the rainwater drainage fitting 1 is not limited to the above, and it is sufficient that the contracted section 28, whose water flow area is smaller than that of the first end 11, is located between the first end 11 and the second end 12.

[0026] Each protrusion 20 is arranged so as to face another protrusion 20 at a circumferential position on the opposite side across the tube axis. In the case of this embodiment, as described above, when viewed along the tube axis, the four protrusions 20 are arranged at equal angular intervals, so that two pairs of protrusions 20 are arranged facing each other across the tube axis. Each upper edge 21 of these protrusions 20 forms a thin, inclined surface that protrudes into the flow path. These inclined surfaces connect to inner wall surface 13a at the top end of each upper edge 21, and the height at which they protrude from inner wall surface 13a gradually increases from this top end position toward the downstream side, until they reach their highest point at connection point 23. The thin inclined surface formed by upper edges 21 arranged in this manner faces rainwater flowing down from the upstream side, and as this rainwater hits the inclined surface, it creates flow path resistance.

[0027] Each lower edge 22 of each protrusion 20 also forms a thin inclined surface that protrudes into the flow path. These inclined surfaces connect to inner wall surface 13a at the lowest end position of the lower edge 22, and the protrusion height from inner wall surface 13a gradually increases from this lowest end position toward the upstream side, until it reaches its highest protrusion height from inner wall surface 13a at the connection point 23. In other words, the inclined surface formed on each upper edge 21 and the inclined surface formed on each lower edge 22 have the same shape and dimensions, but their inclination directions are opposite in the vertical direction, with connection point 23 as the boundary.

[0028] The left side surface 24 and the right side surface 25 of each protrusion 20 are flat surfaces each having an isosceles triangle shape and are parallel to each other. Therefore, each protrusion 20 has a constant thickness from its upper end to its lower end. Because the left side surface 24 and the right side surface 25 extend into the flow path, when rainwater passes through each protrusion 20, it applies viscous resistance due to contact with the left side surface 24 and the right side surface 25. Therefore, the rainwater is applied with both resistance due to contact with the inclined surface formed by the upper edge 21 and viscous resistance due to contact with the left side surface 24 and the right side surface 25.

[0029] The shape of the protrusion 20 is not limited to the isosceles triangle shown in FIG. 3, but may be, for example, a right triangle or a trapezoid.

[0030] (Second embodiment) As shown in FIG. 4, a joint with protrusions (rainwater drainage joint) 1B of the second embodiment has a joint body 50, a plurality of protrusions 51, and a ring 52 with protrusions. The fitting body 50 has a straight pipe section 13 which is a cylindrical pipe having a pipe axis along the vertical direction, an inlet side joint section 11 formed integrally with the upper end of the straight pipe section 13, and an outlet side joint section 12 connected coaxially to the lower end of the straight pipe section 13.

[0031] A ring 52 with projections, which has projections 51 on its inner circumferential surface, is integrally connected to the outlet-side mating portion 12 via a connecting portion 54a. The ring 52 with protrusions has an upstream edge 52a located relatively upstream, a downstream edge 52b located relatively downstream, a flow contraction section 52c connecting the upstream edge 52a and the downstream edge 52b, and a plurality of protrusions 51 arranged at equal angular intervals circumferentially around the pipe axis on the inner surface of the flow contraction section 52c.

[0032] The upstream edge 52a and the downstream edge 52b are both annular flange portions with outer diameters close to the inner diameter of the inner circumferential surface of the straight pipe section 13. Therefore, the upstream edge 52a and the downstream edge 52b can contact the inner wall surface 13a of the straight pipe section 13 without any gaps. When viewed in a cross section including the pipe axis, the inner circumferential surface of the upstream edge 52a gradually becomes thicker from the upstream side to the downstream side. Therefore, although the upstream edge 52a is inserted into the straight pipe section 13, it does not create an excessively large step with respect to the inner wall surface 13a, allowing rainwater passing through it to pass smoothly without disruption. The downstream edge 52b is smoothly connected to the upper end of the connecting portion 54a without creating an excessively large step. Therefore, the downstream edge 52b allows the flow of rainwater passing through it to pass smoothly without disruption. In addition, the downstream edge 52b forms an annular gap with the inner surface of the outlet-side joint portion 12, and the lower end of the straight pipe portion 13 is fitted watertight into this annular gap.

[0033] The contracted section 52c has an arch-like shape in a cross section including the tube axis, with the upper half from the upstream side to the midpoint in the tube axis direction forming a contracted flow path, and the lower half from the midpoint toward the downstream side in the tube axis direction forming an expanded flow path. That is, in the upper half, the inner diameter of the circular opening as viewed along the tube axis gradually decreases from the upstream side to the downstream side, reaching a minimum inner diameter at the boundary with the lower half. Then, in the following lower half, the inner diameter of the circular opening as viewed along the tube axis gradually increases from the minimum inner diameter as viewed from the upstream side to the downstream side, and finally becomes equal to the inner diameter of the connecting section 54a at the boundary with the connecting section 54a.

[0034] Each protrusion 51 is a substantially linear protrusion having an upper end 51a located at the most upstream side in the tube axis direction and a lower end 51b located at the most downstream side in the tube axis direction. When viewed along the tube axis direction, the lower end 51b of each protrusion 51 is located at a position slightly shifted laterally from directly below the upper end 51a. Therefore, each protrusion 51 is disposed at an angle so that a line connecting these upper ends 51a and lower ends 51b intersects with the tube axis when superimposed. Then, an inclined flow path is formed between adjacent protrusions 51 along a direction that intersects with the tube axis when superimposed.

[0035] When viewed in a cross section perpendicular to the line connecting the upper end 51a and the lower end 51b, each protrusion 51 has a substantially triangular cross-sectional shape at each position on the line. The height of this triangular cross-section gradually increases from the upper end 51a to the center of the line, and then gradually decreases from the center of the line to the lower end 51b. When viewed from opposite sides, the width of each protrusion 51 gradually increases from the upper end 51a to the center of the line, and then gradually decreases from the center of the line to the lower end 51b. In other words, each protrusion 51 is thickest at the center in the tube axis direction and gradually becomes thinner from the center toward the upper end 51a. Similarly, each protrusion 51 gradually becomes thinner from the center toward the lower end 51b. Furthermore, when each protrusion 51 is viewed in a cross section that includes a straight line connecting the upper end 51a and the lower end 51b and is along the thickness direction of the wall of the contraction section 52c, it forms a convex arch shape that follows the inner surface of the contraction section 52c. Each protrusion 51 can gradually increase the flow resistance to rainwater along the pipe axis direction.

[0036] According to the protruding portion-equipped joint 1B, rainwater with its flow rate reduced temporarily accumulates in the flow path between the upper side of each protruding portion 51 and the inlet 220 (see FIG. 2). This makes it difficult for air to get into the rainwater flowing into the inlet 220, making it possible to reliably induce the siphon effect. Moreover, because the rainwater has already been rectified after passing through each protruding portion 51, it is drained smoothly without swirling. In addition, the protrusion ring 52 on which each protrusion 51 is formed is integrated with the outlet-side fitting 12. This makes it easy to install and replace each protrusion 51, as well as to perform maintenance such as cleaning.

[0037] According to the rainwater drainage joint 1B of the second embodiment described above, similar to the first embodiment, high drainage performance can be maintained by the siphon effect, and further, maintenance inside the piping can be easily carried out.

[0038] (Third embodiment) As shown in FIG. 5, a joint with protrusions (rainwater drainage joint) 1C of the second embodiment has a joint body 10, an inner pipe 61, and a plurality of protrusions 20. The inner pipe 61 is arranged coaxially inside the joint body 10. The inner pipe 61 is configured in an inverted truncated cone shape that tapers from the upstream side to the downstream side along the pipe axis. The inner pipe 61 has an inner wall surface 61a and an outer wall surface 61b that taper downward. A circular inlet opening is formed at the upper end of the inner pipe 61, and a circular outlet opening with a smaller diameter than the upper end is formed at the lower end of the inner pipe 61. The outer wall surface 61b of the inner pipe 61 is fixed by a pair of protrusions 20 in a spaced-apart state relative to the inner wall surface 13a of the straight pipe section 13.

[0039] As a result, two flow paths are formed within the protruding joint 1C: a first flow path formed between the inner wall surface 13a and the outer wall surface 61b, and a second flow path formed within the inner wall surface 61a. Therefore, rainwater flowing into this protruding joint 1C branches into two paths: one that flows through the first flow path and one that flows through the second flow path. Of these, rainwater flowing through the first flow path slows down due to flow path resistance caused by the reduced flow path area. Meanwhile, rainwater flowing through the second flow path slows down due to flow path resistance caused by hitting the pair of protrusions 20.

[0040] Furthermore, rainwater that tries to pass through while swirling can be rectified by each protrusion 20. Therefore, the protrusion-equipped joint 1C can impart appropriate flow resistance to the rainwater, reducing the flow rate, while also rectifying the rainwater flow at the same time.

[0041] As a result, with the configuration of protruding joint 1C, rainwater with its flow rate reduced temporarily accumulates in the flow paths between the first flow path and the second flow path and the inlet 220. This makes it difficult for air to get into the rainwater flowing into the inlet 220, making it possible to reliably induce the siphon effect.

[0042] According to the rainwater drainage joint 1C of the third embodiment described above, like the other embodiments, high drainage performance can be maintained by the siphon effect, and further, maintenance of the piping 2 can be easily performed.

[0043] The rainwater drainage joint 1 is not limited to the above-described configuration having the protrusion 20, and the inner diameter of the joint itself may be small.

[0044] As shown in FIG. 2, the rainwater drainage joint 1 is preferably positioned so that the vertical length L1 from its upper or lower end to the confluence 112 is at least 1000 mm. Here, the vertical length L1 may refer to the length from the lower end of the horizontal opening of the confluence 112 to the start point B of the contraction 28, or the length from the lower end C of the contraction 28 to the upper end of the horizontal opening 6a of the confluence 112. The confluence 112 may represent, for example, the confluence portion of the confluence pipe 111 (horizontal draw pipe 110) as shown in FIG. 2. The confluence 112 may be configured such that a branch pipe (horizontal draw pipe 110) of the same diameter as the main pipe (piping 2) is connected to each connection port of an elbow or tee, or a pipe of a different diameter is connected. In particular, in the case of a special-shaped tee, it is preferable to connect a pipe with a smaller cross-sectional area than the main pipe as the branch pipe. By connecting a branch pipe with a smaller cross-sectional area than the main pipe, the drainage volume of the branch pipe becomes larger than that of the main pipe. As a result, even if rainwater flows in from the branch pipe at the confluence 112, the drainage volume of the main pipe is large enough to prevent the flow of rainwater from stagnating within the main pipe.

[0045] According to the above configuration, rainwater with its flow rate reduced temporarily accumulates in the flow path between the upper side 21 of each protrusion 20 and the bent portion 6, making it difficult for air to enter the rainwater flowing into the rainwater drainage fitting 1 and ensuring the siphon effect. Moreover, because the rainwater has already been rectified by the left side surface 24 and the right side surface 25 after passing through each protrusion 20, it is drained smoothly without swirling.

[0046] (Fourth embodiment) As shown in FIG. 6, a joint with protrusions (rainwater drainage joint) 1D of the fourth embodiment has a joint body 50, three protrusions 51, and a ring 52 with protrusions. The fitting body 50 has a straight pipe section 13 which is a cylindrical pipe having a pipe axis along the vertical direction, an inlet side joint section 11 formed integrally with the upper end of the straight pipe section 13, and an outlet side joint section 12 connected coaxially to the lower end of the straight pipe section 13.

[0047] A ring 52 with projections having three projections 51 is integrally connected to the outlet-side mating portion 12 via a connecting portion 54a. The three protrusions 51 of the protrusion-equipped ring 52 extend from the ring body 55 toward the tube axis of the straight tube portion 13 .

[0048] The ring body 55 is annular and has an outer diameter close to the inner diameter of the inner circumferential surface of the straight pipe portion 13. Therefore, the ring body 55 can contact the inner wall surface 13a of the straight pipe portion 13 without leaving a gap.

[0049] The three protrusions 51 are connected to each other along the pipe axis of the straight pipe section 13, and form a protrusion 56 that protrudes relatively toward the upstream side when viewed from the ring body 55. The radial length of the protrusion 51 becomes relatively smaller toward the upstream side. Therefore, the protrusion 56 made up of the three protrusions 51 has a convex shape toward the upstream side. In this embodiment, the three protrusions 51 are arranged at equal angular intervals when viewed along the pipe axis. The protrusions 56 form a thin inclined surface from upstream to downstream within the flow path. The thin inclined surface formed by the protrusions 56 arranged in this manner faces rainwater flowing down from the upstream side. As a result, this rainwater hits the inclined surface, creating flow path resistance.

[0050] The left side surface 24 and the right side surface 25 of each protrusion 51 are parallel to each other. Therefore, the thickness of each protrusion 51 is constant at each position from its top end to its bottom end. Because the left side surface 24 and the right side surface 25 extend into the flow path, when rainwater passes through each protrusion 51, the left side surface 24 and the right side surface 25 apply viscous resistance to the rainwater as the rainwater comes into contact with the protrusion 51. Therefore, the rainwater is subjected to both resistance due to contact with the inclined surface and viscous resistance due to contact with the left side surface 24 and the right side surface 25. That is, each protrusion 51 can apply flow resistance to rainwater so that it gradually increases downstream.

[0051] According to the protruding portion-equipped joint 1D, rainwater with its flow rate reduced temporarily accumulates in the flow path between the upper side of each protruding portion 51 and the inlet 220 (see FIG. 2). This makes it difficult for air to get into the rainwater flowing into the inlet 220, making it possible to reliably induce the siphon effect. Moreover, because the rainwater has already been rectified after passing through each protruding portion 51, it is drained smoothly without swirling. In addition, the protrusion ring 52 on which each protrusion 51 is formed is integrated with the outlet-side fitting 12. This makes it easy to install and replace each protrusion 51, as well as to perform maintenance such as cleaning.

[0052] According to the rainwater drainage joint 1D of the fourth embodiment described above, like the other embodiments, high drainage performance can be maintained by the siphon effect, and further, maintenance inside the piping can be easily performed.

[0053] (Fifth embodiment) As shown in FIG. 7, a joint with protrusions (rainwater drainage joint) 1E of the fifth embodiment has a joint body 10 and an inner pipe 61. The inner pipe 61 is arranged coaxially inside the joint body 10. The inner pipe 61 is configured in an inverted truncated cone shape that tapers from the upstream side to the downstream side along the pipe axis. The inner pipe 61 has an inner wall surface 61a and an outer wall surface 61b that taper downward. A circular inlet opening is formed at the upper end of the inner pipe 61, and a circular outlet opening with a smaller diameter than the upper end is formed at the lower end of the inner pipe 61. The inner wall surface 61a of the inner pipe 61 is connected to the inner wall surface 13a of the straight pipe section 13 without any steps.

[0054] As a result, rainwater flowing inside the inner pipe 61 in the joint with protrusion 1E is subjected to flow resistance due to the reduced flow path area, and is decelerated.

[0055] As a result, with the configuration of the protruding joint 1E, rainwater with its flow rate reduced temporarily accumulates in the flow path between the inner pipe 61 and the inlet 220. This makes it difficult for air to get into the rainwater flowing into the inlet 220, making it possible to reliably induce the siphon effect.

[0056] According to the rainwater drainage joint 1E of the fifth embodiment described above, similarly to the other embodiments, high drainage performance can be maintained by the siphon effect.

[0057] The outer periphery of the straight pipe section 13 of the rainwater drainage joint 1 may be wrapped with a heat insulating material (such as glass wool or rock wool) or sound insulating material. The flow velocity increases in the contracted section 28, making it easier for drainage noise to be transmitted inside the building 200. This configuration can prevent drainage noise from diffusing inside the building.

[0058] The rainwater drainage joint 1 may be fire-resistant. Specifically, a fire-resistant material may be wrapped around the outer periphery of the rainwater drainage joint 1, or a heat-expandable fire-resistant layer may be attached to the inside of the joint. The fire-resistant layer may be formed from a thermoplastic resin composition containing heat-expandable graphite. This configuration makes it easier for the rainwater drainage joint 1 to penetrate the fire compartment (slab), and also makes it possible to provide a rainwater drainage system 100 with high fire resistance.

[0059] A mark may be placed on the outer surface of the rainwater drainage fitting 1 to indicate the direction in which the rainwater drainage fitting 1 is connected to the pipe 2. For example, the mark may be a mark that makes it possible to identify which of the two ends of the rainwater drainage fitting 1 is the first end 11 through which rainwater flows in or the second end 12 through which rainwater flows out. The mark may be an engraving or may be printed. The mark may be a symbol such as an arrow, or may be a letter. If a mark is placed on the outer surface of the rainwater drainage joint 1, it becomes easier to connect the rainwater drainage joint 1 in the correct orientation during construction, improving workability. Furthermore, when checking the construction after completion, it is possible to check whether the orientation of the rainwater drainage joint 1 is correct by checking the markings on the outer surface.

[0060] 8 to 14 show an example of a fixing part 3 for fixing a rainwater drainage joint 1 to a pipe 2 (upper pipe or lower pipe). In this embodiment, the end of the rainwater drainage joint 1 and the end of the pipe 2 (upper pipe or lower pipe) are mechanically joined together. For example, a flange joint or a housing joint can be used as the mechanical joint.

[0061] FIG. 8 shows a fixing portion 3A when the rainwater drainage joint 1 and the pipe 2 (upper pipe or lower pipe) are flange-connected. When the rainwater drainage fitting 1 and the pipe 2 (upper pipe or lower pipe) are fixed by flange joints, a processed pipe 4 is provided at the lower end of the upper pipe 2a, the upper end of the lower pipe 2b, and the first end 11 and second end 12 of the rainwater drainage fitting 1. The processed pipe 4 is butt-welded to the pipe 2 or the rainwater drainage fitting 1. The bead 5 between the processed pipe 4 and the pipe 2 or the rainwater drainage fitting 1 is generated when the processed pipe 4 is butt-welded to the pipe 2 or the rainwater drainage fitting 1. The processed pipe 4 is a so-called injection-molded product. At least one of the inner diameter and the outer diameter of the processed pipe 4 is not uniform over substantially its entire length. The processed pipe 4 is provided with a flange 31. In the illustrated example, the processed pipe 4 connected to the lower end of the upper pipe 2a and the processed pipe 4 connected to the first end 11 of the rainwater drainage fitting 1 are fixed by flange joints, but the connection to the lower pipe 2b may also be fixed by flange joints.

[0062] Each flange 31 (32) is, for example, integral with the processing pipe 4. Each flange 31 (32) may be, for example, separate from the processing pipe 4. The flange 31 (32) may be movable relative to the processing pipe 4 in the vertical direction. In other words, the flange 31 (32) may be a so-called loose flange. In addition, as the flange 31 (32), a joint component including a flange 31 (32) independent of the processed pipe 4 (for example, a flexible joint for drainage steel pipes specified in the Japan Metal Joints Association standard "JPF MDJ-002") may be used. For example, the piping 2 and the processed pipe 4 may be integrally molded by extrusion molding, and the flange 31 (32) may be post-processed onto the integrally molded piping 2 and processed pipe 4.

[0063] Furthermore, the pipe 2 and the rainwater drainage joint 1 are flange-joined radially outward from the outer circumferential surfaces of the pipe 2 and the rainwater drainage joint 1. A bolt joint utilizing flanges 31 (32) is used to flange-join the pipe 2 and the rainwater drainage joint 1. The bolts 33 and nuts 34 are arranged radially outward from the outer circumferential surfaces of the pipe 2 and the rainwater drainage joint 1. As a result, the pipe 2 and the rainwater drainage joint 1 are joined by the bolts 33 and nuts 34 radially outward from the outer circumferential surfaces of the pipe 2 and the rainwater drainage joint 1. The bolt 33 passes through the flange 31 and the flange 32 in the vertical direction. The head of the bolt 33 and the nut 34 sandwich the flange 31 and the flange 32 in the vertical direction. In this way, the pipe 2 and the rainwater drainage joint 1 are fixed by the bolt.

[0064] Here, the flange joint is provided with a packing 35 (gasket). The piping 2 and the rainwater drainage joint 1 are provided with packing contact portions 31a, 32a. The packing contact portions 31a, 32a are portions with which the packing 35 comes into contact. The packing 35 seals the gap between the piping 2 and the rainwater drainage joint 1. The packing 35 may be an elastic material (e.g., rubber) or may not be an elastic material. The packing 35 is annular. The packing 35 is disposed, for example, between the flanges 31 and 32. The packing 35, together with the flanges 31 and 32, is sandwiched vertically by bolts 33 and nuts 34. The packing contact portions 31a, 32a are provided on the end faces of the piping 2 and the rainwater drainage joint 1. This improves the sealing performance at the joint between the piping 2 and the rainwater drainage joint 1. This ensures watertightness of the rainwater drainage joint 1 relative to the pipe 2. This prevents air from entering the pipe 2 and water from leaking from the pipe 2, ensuring that the siphon phenomenon is induced.

[0065] In this embodiment, the processed pipes 4 are provided at the ends of the pipe 2 and the rainwater drainage joint 1, but the processed pipes 4 may not be provided. For example, the flanges 31 (32) may be provided directly at the ends of the pipe 2 and the rainwater drainage joint 1. In this case, the flanges 31 (32) may be formed integrally with the pipe 2 by processing the end of the pipe 2 manufactured by extrusion molding. In this case, the bead 5 may not be required.

[0066] When processed pipes 4 are provided at the ends of the pipe 2 and the rainwater drainage joint 1 and flange-jointed, the pipe 2 and the rainwater drainage joint 1 are preferably polyethylene pipes. When flanges 31 (32) are provided directly at the ends of the pipe 2 and the rainwater drainage joint 1, the material is not particularly limited, and may be, for example, stainless steel, carbon steel, polyethylene, or polyvinyl chloride. Furthermore, when flanges 31 (32) are provided directly at the ends of the pipe 2 and the rainwater drainage joint 1, a double-walled fireproof pipe may be used. A double-walled fireproof pipe has an inner pipe made of polyvinyl chloride and an outer pipe made of fiber mortar, and is excellent in soundproofing against water flow noise, corrosion resistance, earthquake resistance, fire resistance, etc. In particular, when the pipe 2 is a fire-resistant double-layer pipe, the inner pipe is a rigid polyvinyl chloride pipe, and if the rainwater drainage joint 1 is made of rigid polyvinyl chloride resin, the pipe 2 and the rainwater drainage joint 1 can be joined with adhesive, making installation easy. In this case, it is preferable that the outer surface of the rainwater drainage joint 1 is also covered with a fiber mortar layer. Furthermore, if the piping 2 is a fire-resistant double-walled pipe, a space is provided between the outer surface of the inner pipe (hard vinyl chloride) and the inner surface of the outer pipe (fiber mortar). Violent vibration of the inner pipe due to siphoning rainwater drainage can cause the inner and outer pipes to come into contact, generating noise and potentially damaging the inner or outer pipes. To prevent the inner pipe from vibrating due to siphoning, a sheet- or ring-shaped spacer can be provided between the outer surface of the inner pipe (hard vinyl chloride) and the inner surface of the outer pipe (fiber mortar), or the space between the inner and outer pipes can be completely filled with a spacer. Examples of spacers include elastic materials such as synthetic rubber and acrylic rubber; synthetic resins such as polyethylene and polypropylene; foamed plastics and porous synthetic resins made from foamed polystyrene, polypropylene, polyethylene, polyurethane, etc.; and inorganic or organic fiber materials such as glass wool, rock wool, polyester felt, and paper.

[0067] 9 and 10 show a fixing part 3B when the rainwater drainage joint 1 and the pipe 2 (upper pipe or lower pipe) are joined by a housing joint. 9, a fixing portion 3B between the rainwater drainage joint 1 and the pipe 2 includes a joining member 30. That is, instead of flange joining, the rainwater drainage joint 1 is joined and fixed to the pipe 2 using the joining member 30.

[0068] The joining member 30 is divided into two parts in the circumferential direction. The joining member 30 comprises two divided bodies as a joint. Each divided body has a protrusion 36 protruding from both ends of its semicircular arc shape. The semicircular arc portions of each divided body are overlapped and arranged along the outer periphery of the pipe 2 and the rainwater drainage joint 1. The protrusion 36 protrudes outward in the circumferential direction relative to the pipe 2 and the rainwater drainage joint 1. The two divided bodies are joined at each protrusion 36 with a bolt 33 and a nut (not shown).

[0069] The bolt 33 passes horizontally through each of the protrusions 36 of the two overlapping segments. The head and nut of the bolt 33 horizontally sandwich the overlapping protrusions 36 together. This allows the two segments to join the pipe 2 and the rainwater drainage joint 1 by horizontally sandwiching them together. Tightening the bolt 33 increases the strength with which the two segments (i.e., the joining member 30) grip the pipe 2 and the rainwater drainage joint 1.

[0070] It is also possible to use other configurations conforming to the Japan Water Works Association standard "Metal Joints for Polyethylene Pipes for Water Supply" (JWWA B 116:2012) instead of the connecting member 30. For example, the bolt 33 may penetrate the protruding piece 36 of the connecting member 30 vertically rather than horizontally. Even in this case, it is possible to use a configuration in which the strength with which the connecting member 30 grips the main pipe and the rainwater drainage joint 1 is increased by tightening the bolt 33.

[0071] As shown in Figure 10, grooves 37 are provided on the outer periphery of the processed pipe 4. The grooves 37 extend circumferentially around the outer periphery of the processed pipe 4. The grooves 37 extend continuously around the entire circumferential circumference. Both axial ends of the joining member 30 fit into each groove 37. This makes the joining of the piping 2 and the rainwater drainage joint 1 by the joining member 30 stronger.

[0072] Furthermore, packings 35 are fitted to the pipe 2 and the rainwater drainage joint 1 from the outside in the radial direction. One packing 35 is fitted across the pipe 2 side and the rainwater drainage joint 1 side. The packing 35 is covered from the outside in the radial direction by the joining member 30. The packing 35 is located between the upper end and the lower end of the joining member 30.

[0073] Gasket contact portions 31a and 32a are provided on the outer peripheral surface of the processed pipe 4. The gasket contact portions 31a and 32a are portions of the outer peripheral surface of the processed pipe 4 that are located closer to the joint than the groove. In this way, because the gasket contact portions 31a and 32a are on the outer peripheral surface rather than on the end faces of the piping 2 and the rainwater drainage joint 1, the end faces of the piping 2 and the rainwater drainage joint 1 butt against each other.

[0074] This structure ensures watertightness of the rainwater drainage joint 1 relative to the pipe 2. This prevents air from entering the pipe 2 and water from leaking from the pipe 2, ensuring that the siphon phenomenon is induced.

[0075] The ends of the pipe 2 and the rainwater drainage joint 1 do not necessarily need to have the processed pipe 4. For example, a groove may be provided directly on the end of the pipe 2. In this case, the groove can be formed in the pipe 2 by, for example, cutting the end of the pipe 2 manufactured by extrusion molding. In this case, the bead 5 does not need to be provided. When the processed pipe 4 is provided on the ends of the pipe 2 and the rainwater drainage joint 1 and joined with the joining member 30, the pipe 2 and the rainwater drainage joint 1 are preferably polyethylene pipes. When the joining member 30 is provided directly on the ends of the pipe 2 and the rainwater drainage joint 1, the material thereof is not particularly limited and may be, for example, stainless steel, carbon steel, polyethylene, or polyvinyl chloride.

[0076] In the case of housing joints and flange connections that use screws such as those described above, spring washers, U-nuts, or double nuts may be used to secure the screws so that they do not loosen due to vibrations during drainage.

[0077] 11A and 11B show a fixing part 3D when the rainwater drainage joint 1 and the pipe 2 (upper pipe or lower pipe) are connected by an E-lock joint. Note that Fig. 11A shows a partial cross-sectional view of the fixing part 3D in a state before the rainwater drainage joint 1 and the pipe 2 are connected (unconnected state), and Fig. 11B shows a partial cross-sectional view of the fixing part 3D in a state after the rainwater drainage joint 1 and the pipe 2 are connected (connected state).

[0078] As shown in FIG. 11A, the fixing portion 3D when connected by an E-lock joint includes a socket 70 and a spigot 80. The socket 70 includes a socket main body 71, a locking portion 72, a first packing 73, a second packing 74, and a lock ring 75. The socket main body 71 has a first step 71a and a second step 71b on its inner circumferential surface and a third step 71c on its outer circumferential surface. The locking portion 72 is provided circumferentially along a portion of the socket main body 71 in the axial direction. A portion of the locking portion 72 protrudes from the inner circumferential surface of the socket main body 71, forming a convex portion on the inner circumferential surface of the socket main body 71. The locking portion 72 is elastically deformable. For example, the locking portion 72 is elastically deformable so that the peripheral ends move apart in the circumferential direction. In this case, the locking portion 72 expands in diameter. The locking portions 72 are elastically deformable, for example, so that their peripheral ends approach each other in the circumferential direction. In this case, the diameter of the locking portions 72 decreases. The first packing 73 is an annular rubber ring and is disposed on the first step portion 71a of the receptacle body 71. The second packing 74 is an annular rubber ring and is disposed on the second step portion 71b of the receptacle body 71. The locking ring 75 has a ring portion 75a that covers part of the outer peripheral surface of the receptacle body 71 in the pipe axis direction, and a claw portion 75b. The locking ring 75 is disposed on the outer surface of the receptacle body 71 so as to be movable in the pipe axis direction. The locking portions 72, the first step portion 71a, and the second step portion 71b are disposed in this order from the opening of the receptacle 70 in the pipe axis direction.

[0079] Spigot 80 has recess 81 and fourth step 82. Recess 81 is a portion that is provided continuously in the circumferential direction on the outer surface of spigot 80 and has a diameter smaller than the outer diameter of spigot 80.

[0080] 11B , by inserting the spigot 80 into the socket 70, the rainwater drainage fitting 1 and the pipe 2 (the upper pipe or the lower pipe) are connected. Specifically, the spigot 80 is inserted into the socket 70, and the locking ring 75 on the outer circumferential surface of the socket 70 is moved to a predetermined position. At this time, the locking portion 72 of the socket 70 engages with the recess 81 of the socket 70, and the ring portion 75a of the locking ring 75 presses the locking portion 72 from the outer circumferential surface of the socket, thereby preventing the locking portion 72 from disengaging from the recess 81 and restricting movement of the socket 80 in the pipe axis direction relative to the socket 70. Here, "moving the locking ring 75 to a predetermined position" may also mean moving the locking ring 75 toward the open end of the socket 70 until the tab portion 75b of the locking ring 75 abuts against the third step portion 71c provided on the outer circumferential surface of the socket main body 71.

[0081] At this time, the first gasket 73 provided on the first step 71a of the socket 70 abuts against the fourth step 82 of the spigot 80, and further the second gasket 74 provided on the second step 71b of the socket 70 abuts against the opening end of the spigot 80, thereby connecting the socket 70 and the spigot 80 airtightly.

[0082] FIG. 12 shows a fixing portion (electrically fused portion) 3C when the rainwater drainage joint 1 and the pipe 2 (upper pipe or lower pipe) are fixed by electrical fusion. The electric fusion joint includes a main body 41, an electric heating wire 42, and a terminal 43. The main body 41 is a pipe (straight pipe) made of polyolefin resin. The ends of the pipe 2 and the rainwater drainage joint 1 are fitted into the main body 41. The electric heating wire 42 is embedded in the main body 41. The electric heating wire 42 forms a spiral in the circumferential direction of the main body 41. The terminal 43 applies a voltage to the electric heating wire 42. Two terminals 43 are provided on the main body 41. The two terminals 43 are connected to the positive and negative poles of a power supply (not shown). The power supply connected to the terminal 43 applies a voltage to the electric heating wire 42. The electric heating wire 42 generates heat, and the main body 41 melts together with the pipe 2 and the rainwater drainage joint 1, thereby achieving electric fusion joining.

[0083] FIG. 13 shows an exploded view of a fixing part (electrically fused part) 3E when the rainwater drainage joint 1 and the pipe 2 (upper pipe or lower pipe) are fixed by electrical fusion. The electrofusion joint of the fixed part (electrical fusion part) 3E includes a socket 91, a spigot 92, a heating wire, and a terminal 43. The socket 91 and the spigot 92 have approximately the same outer diameter. The heating wire is embedded in the spigot 92. The heating wire forms a spiral in the circumferential direction inside the spigot 92. The terminal 43 applies a voltage to the heating wire. Two terminals 43 are provided on the spigot 92. The two terminals 43 are connected to the positive and negative poles of a power supply (not shown). The power supply connected to the terminal 43 applies a voltage to the heating wire. The heating wire generates heat, and the spigot 92 melts together with the socket 91, thereby achieving electrofusion welding. With such a fixing portion 3E, the outer diameter of the fixing portion is approximately the same for the socket 91 and the spigot 92, and therefore the appearance is excellent.

[0084] FIG. 14 shows a fixing portion (electrically fused portion) 3F when the rainwater drainage joint 1 and the pipe 2 (upper pipe or lower pipe) are fixed by electrical fusion. The electric fusion joint includes a main body 41, a heating wire 42, and a terminal 43. The main body 41 is a pipe (straight pipe) made of polyolefin resin. The rainwater drainage joint 1 and the pipe 2 each have a connection part 93. The connection part 93 is a part with a reduced outer diameter and is housed inside the main body 41. The connection parts 93 of the pipe 2 and the rainwater drainage joint 1 are fitted into the main body 41. The heating wire 42 is embedded in the main body 41. The heating wire 42 forms a spiral in the circumferential direction of the main body 41. The terminal 43 applies a voltage to the heating wire 42. Two terminals 43 are provided on the main body 41. The two terminals 43 are connected to the positive and negative poles of a power supply (not shown). The power supply connected to the terminal 43 applies a voltage to the heating wire 42. The heating wire 42 generates heat, and the main body 41 melts together with the pipe 2 and the rainwater drainage joint 1, thereby achieving electric fusion joining.

[0085] When the rainwater drainage joint 1 and the pipe 2 (upper pipe or lower pipe) are fixed by electric fusion, the terminal 43 may be configured to be removable from the fixed part after the fixing is completed.

[0086] As described above, the rainwater drainage joint 1 of this embodiment has a first end 11 through which rainwater flows in, a second end 12 through which rainwater flows out, and a reduced section 28 between the first end 11 and the second end 12, which has a water flow area smaller than the water flow area of ​​the first end 11, and the first end 11 and the second end 12 are fixed to other components with bolts. In a large-scale stormwater drainage system 100 with a large discharge volume, the increase in flow velocity at the contraction section 28 becomes significant, causing the vibration of the drain pipe to increase. In this case, if the first end 11 and the second end 12 are fixed to the piping 2 with bolts as described above, water leakage can be prevented even if stress is concentrated at the connection between the drain pipe and the contraction section 28. Therefore, the strength of the connection can be maintained while maintaining a high discharge volume.

[0087] In addition, the rainwater drainage joint 1 in this embodiment has a first end 11 through which rainwater flows in, a second end 12 through which rainwater flows out, and a reduced section 28 between the first end 11 and the second end 12, which has a water flow area smaller than the water flow area of ​​the first end 11, and the first end 11 and the second end 12 may be joined to other members by electrical fusion. If the first end 11 and the second end 12 are electrically fused to the pipe 2, water leakage can be prevented even if stress is concentrated at the connection between the pipe and the contracted section 28. This makes it possible to maintain the strength of the connection while maintaining a high discharge rate. Furthermore, if the first end 11 and the second end 12 are electrically fused to the pipe 2, the space required for installation is small. This makes it easier to secure installation space, especially for indoor piping where installation space is limited.

[0088] The reduced portion 28 may also have a protrusion 20 extending toward the center of the tube axis. With this configuration, rainwater with its flow rate reduced temporarily accumulates in the flow path between the pipe 2 and the upper edge 21 of each protrusion 20, making it difficult for air to enter the rainwater flowing into the rainwater drainage fitting 1, and making it possible to reliably induce the siphon effect. Moreover, because the rainwater has already been rectified after passing through each protrusion 20, it is drained smoothly without swirling. This makes it possible to maintain a higher drainage volume.

[0089] Furthermore, in the rainwater drainage system 100 of this embodiment, the rainwater drainage joint 1 is connected at a distance of 1000 mm or more from the bent portion 6. With this structure, a siphon can be induced when a certain amount of water has accumulated upstream of the rainwater drainage joint 1. As a result, when rainwater passes through the contracted section 28 of the rainwater drainage joint 1, a large negative pressure is applied, causing the rainwater to flow downstream in one go. This makes it possible to maintain a higher drainage volume.

[0090] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and configuration changes, combinations, deletions, etc. are also included within the scope that does not deviate from the gist of the present invention.

[0091] For example, a fixing device may be used to fix a part of the rainwater drainage system 1 to a wall surface. In such a case, it is preferable to arrange the fixing device within 300 mm from the rainwater drainage joint 1 of the rainwater drainage system 1. [Explanation of symbols]

[0092] 100 Stormwater drainage system 1. Rainwater drainage joint 11 First end 12 Second end 20, 51 protrusion 28 Reduction section 6 Bend

Claims

1. a first end into which rainwater flows; a second end from which rainwater flows out; a reduced portion between the first end and the second end, the reduced portion having a water passage area smaller than the water passage area of ​​the first end, The first end and the second end are fixed to another member by bolts. Rainwater drainage fittings.

2. a first end into which rainwater flows; a second end from which rainwater flows out; a reduced portion between the first end and the second end, the reduced portion having a water passage area smaller than the water passage area of ​​the first end, The first end and the second end are joined to another member by electrofusion. Rainwater drainage fittings.

3. The reduced portion has a protrusion extending toward the center of the tube axis. A rainwater drainage joint according to claim 1 or 2.

4. Fire-resistant, A rainwater drainage joint according to claim 1 or 2.

5. a pipe connected to the inlet; The rainwater drainage joint according to claim 1 or 2, which is connected to the pipe. Stormwater drainage system.

6. Branch pipes and a junction where the branch pipe and the pipe join together, The confluence is provided downstream of the rainwater drainage joint, The vertical length from the lower end of the rainwater drainage joint to the confluence is 1000 mm or more, The stormwater drainage system according to claim 5.

7. A building comprising the storm water drainage system according to claim 5.

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