Drainage structure

Abstract

To provide a drainage structure capable of reliably inducing a siphon phenomenon and improving drainage capacity.SOLUTION: This drainage structure includes a catch basin that takes in rainwater, and a finned joint 70 arranged below a bottom wall 53e of the catch basin. The finned joint 70 includes a joint body 80 having an inner wall surface 83a that defines an internal flow path that communicates with a circular opening 53e1 of the bottom wall 53e, and a plurality of fins 90 that have an upper end relatively on the upstream side and a lower end relatively on the downstream side and are arranged in the flow path along the periphery of the pipe axis of the joint body 80.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a drainage structure. [Background technology]

[0002] Conventionally, for example, in bridges, a concrete deck is provided under the asphalt pavement that forms the road surface. A catchment basin is buried in the basin to drain water from the road surface. The structure described in the following Patent Document 1 is known as an example of this type of catchment basin. This catchment basin has a basin body that is buried in the slab while connected to the upper end of a formwork pipe, and a metal lid that is placed above the basin body at approximately the same height as the road surface. According to the drainage structure with this catchment basin, rainwater on the road surface flows into the basin body through the mesh of the metal lid and is then drained through the formwork pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-001493 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above conventional drainage structure, it is desirable to be able to discharge rainwater at a high flow rate, but air that enters the catch basin together with the rainwater generates a vortex, which inhibits the induction of the siphon phenomenon and limits the drainage performance. Therefore, measures to improve the drainage performance can be considered to increase the diameter of the pipe through which the rainwater flows or to increase the number of catch basins installed. However, in either case, it becomes necessary to form a large opening in the deck. In other words, if the diameter of the pipe is increased, it is necessary to increase the diameter of the hole in the deck through which the pipe passes. In addition, if the number of catch basins installed is increased, it is necessary to increase the number of openings formed in the deck by the number of additional catch basins.

[0005] Here, when openings are formed in the deck, rebar cannot be passed through the openings, so the area around the openings must be reinforced with more rebar than in areas without openings. Therefore, in both cases where the dimensions of the openings are enlarged or the number of openings is increased, it becomes necessary to carry out a strength design that takes into account the reduction in strength and increase the amount of reinforcing rebar. However, such an increase in the amount of rebar is not desirable, as it increases the burden on the bridge piers and affects construction costs. Therefore, a drainage structure that can reliably induce the siphon phenomenon and improve drainage capacity was required.

[0006] The present invention has been made in consideration of the above circumstances, and has an object to provide a drainage structure that can improve drainage capacity. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following means. (1) A drainage structure according to one aspect of the present invention includes: A catchment section that captures rainwater; A first joint disposed below a bottom wall of the water collecting portion; Equipped with The first joint is a joint body having an inner wall surface forming a flow passage therein that communicates with the opening of the bottom wall; a plurality of fins disposed in the flow passage around a pipe axis of the fitting body, the fins having a relatively upstream upper end and a relatively downstream lower end; has. (2) In the drainage structure described in (1) above, The fins may be provided on the inner wall surface such that the upper ends of the fins are located within 1000 mm vertically downward from the opening in the bottom wall. (3) In the drainage structure according to (1) or (2) above, The joint body is an inlet connection port provided at an upstream end of the joint body; and an outlet side connection port provided at a downstream end of the joint body, The joint body may not have any other connection port between the inlet side connection port and the outlet side connection port.

[0008] According to the drainage structure described in (1) above, rainwater that flows into the water collection section is drained to the first joint through the opening formed in the bottom wall thereof. The rainwater that passes through the flow path of the first joint is subjected to flow path resistance by the fins (for example, fins whose upper ends are located within 1000 mm vertically downward from the opening), so that the rainwater tends to temporarily accumulate in the space upstream (above) the fins. This temporary accumulation of rainwater can suppress the intake of air at the opening and suppress the generation of vortexes, so that it is possible to effectively induce the siphon phenomenon at the opening in the bottom wall of the water collection section and improve the drainage performance. In addition, the rainwater that passes through the flow path of the first joint tries to pass while swirling, but since the fins extending along the pipe axis rectify the flow, it is smoothly drained after passing the position of the fins. In addition, when the fins are located at a depth position that is not too far back as viewed from the opening, the garbage in the first joint can be easily removed by accessing it from the opening of the water collection section. This makes it possible to achieve a drainage structure that is highly maintainable while maintaining a configuration that enhances drainage performance.

[0009] (4) In the drainage structure according to any one of (1) to (3) above, The flow path is an inlet opening located at the top end thereof and having an opening area equal to that of the opening in the bottom wall; The inlet opening may have a throttle opening located below the inlet opening and communicating with the inlet opening via a contraction inclined surface. In the case of the drainage structure described in (4) above, rainwater that flows into the inlet opening of the flow path contracts along the contraction slope and flows into the throttle opening. By contracting the rainwater in this way, it is possible to impart flow path resistance due to contraction in addition to the flow path resistance provided by the fins. This makes it possible to more effectively form a temporary pool of rainwater on the upstream side of the first joint, making it possible to more reliably induce the siphon phenomenon.

[0010] (5) In the drainage structure described in (4) above, The fin may be disposed at an outer position avoiding overlap with the throttle opening when the flow passage is viewed along the tube axis. In the case of the drainage structure described in (5) above, it is possible to prevent the fins from excessively interfering with and disrupting the flow of rainwater that is about to pass through the throttle opening having the smallest opening area in the flow path of the first joint.

[0011] (6) In the drainage structure described in any one of (1) to (5) above, the following configuration may be adopted: a second joint connecting the opening of the water collecting portion and an inlet opening of the first joint; a first pipe connected to the outlet opening of the first joint and extending downward; Further equipped with The fin is separate from the joint body and is connected between the joint body and the first pipe. In the case of the drainage structure described in (4) above, rainwater that flows into the catchment section is drained through an opening formed in the bottom wall thereof to the second joint. After passing through the second joint, the rainwater flows into the inlet opening of the subsequent first joint. As the rainwater passes through the flow path of the first joint, it encounters flow path resistance from a fin (for example, a fin whose upper end is located within 1000 mm vertically downward from the opening), and the rainwater tends to temporarily accumulate upstream (above) this fin. Therefore, in the case of this configuration as well, the induction of the siphon phenomenon can be more reliably achieved.

[0012] (7) The drainage structure according to any one of (1) to (5) above may be configured as follows: A second pipe connected to the opening of the water collecting portion and extending laterally; A third pipe having a cleaning port formed at an upper end, a pipe end of the second pipe connected to a side portion, and extending downward; Further equipped with The upper end of the first joint is connected to the lower end of the third pipe. In the case of the drainage structure described in (7) above, the rainwater that flows into the water collection section is drained into the second pipe through an opening formed in the bottom wall. After passing through the second pipe, the rainwater flows into the third pipe. The rainwater that flows down the third pipe then flows into the first joint. Then, the rainwater that passes through the flow path of the first joint is subjected to flow path resistance by a fin (for example, a fin whose upper end is located within 1000 mm vertically downward from the opening), so that the rainwater tends to temporarily accumulate upstream (above) the fin. Therefore, the rainwater tends to temporarily accumulate in the second pipe as well, so that the intake of air into the opening can be suppressed and the induction of the siphon phenomenon can be more reliably induced. In addition, since the fin is located directly below the cleaning port and at a depth that is not too far back, the garbage in the first joint can be easily removed by accessing it from the cleaning port. Effect of the Invention

[0013] According to the drainage structure of each of the above aspects, it is possible to improve the drainage capacity. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram showing a first embodiment of the present invention, and is a perspective view showing a drainage structure installed on the road surface of a road structure (bridge). [Diagram 2] FIG. 2 is a diagram showing the configuration of the drainage structure, and is a vertical cross-sectional view taken along the line AA in FIG. [Diagram 3] FIG. 2 is a vertical cross-sectional view showing the lower manhole of the drainage manhole provided in the drainage structure. [Figure 4] 4 is a view showing a lower basin of a drainage basin provided in the drainage structure, taken along the arrow BB in FIG. 3. FIG. [Diagram 5] 3 is a diagram showing a main part of the drainage structure, and is an enlarged view of part C in FIG. 2. [Figure 6] FIG. 11 is a longitudinal cross-sectional view showing a modified example of a finned joint of the drainage structure, taken along a cross section including the central axis. [Figure 7]FIG. 11 is a longitudinal cross-sectional view showing another modified example of the finned joint of the drainage structure, taken along a cross section including the central axis. [Figure 8] FIG. 11 is a longitudinal cross-sectional view showing yet another modified example of the finned joint of the drainage structure, taken along a cross section including the central axis thereof. [Figure 9] FIG. 13 is a perspective view showing yet another modified example of the finned joint of the drainage structure, with its internal structure seen through. [Figure 10] FIG. 2 is a perspective view of a drain provided in the drainage structure. [Figure 11] FIG. 11 is a perspective view showing a modified example of a drain provided in the drainage structure. [Figure 12] FIG. 11 is a perspective view showing another modified example of the drainage structure. [Figure 13] FIG. 11 is a vertical cross-sectional view of a drainage structure for an eaves gutter according to a second embodiment of the present invention. [Figure 14] 14 is a diagram showing a main part of the drainage structure, and is an enlarged view of part D in FIG. 13. FIG. [Figure 15] FIG. 11 is a diagram showing a third embodiment of the present invention, being a side view in vertical section of a portion of a drainage structure having a cleaning port. [Figure 16] FIG. 13 is a diagram showing a fourth embodiment of the present invention, and is an oblique view showing a drainage structure in which a second joint and a first joint are connected in this order directly below a square box. [Figure 17] FIG. 13 is a perspective view showing a modification of the first embodiment, taken along a vertical cross section including the tube axis. [Figure 18] FIG. 13 is a diagram showing a modified example of the fourth embodiment, and is a perspective view showing a drainage structure in which a drain pipe cover is provided on the downstream side of a downpipe. [Figure 19] 4 is a vertical cross-sectional view showing an example of a drain pipe cover provided in the drainage structure. FIG. [Figure 20] FIG. 10 is a vertical cross-sectional view including a partial side view showing a drainage structure applied to a flat roof according to a fifth embodiment of the present invention. [Figure 21] FIG. 2 is a vertical cross-sectional view partially including a side view, showing a first example of a connection form with a water collection basin in the drainage structure of each embodiment of the present invention. [Figure 22] FIG. 11 is a vertical cross-sectional view partially including a side view showing a second example of a connection form with a water collection basin in the drainage structure of each embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, drainage structures according to embodiments of the present invention will be described with reference to the drawings.

[0016] [First embodiment] <Configuration> Fig. 1 is a perspective view showing a drainage structure 1 (stormwater drainage system 1) according to a first embodiment of the present invention installed on an viaduct (road structure). As shown in Fig. 1, a plurality of drainage structures 1 are arranged along the side gutters of an viaduct H. Rainwater (water) that falls on the viaduct H flows into the drainage structure 1 and is then drained outside the viaduct H.

[0017] Fig. 2 is a diagram showing the configuration of the drainage structure 1, and is a vertical cross-sectional view taken along the line AA in Fig. 1. As shown in Fig. 2, the drainage structure 1 includes a metal cover 10, a catch basin (water collecting portion) 20, a drain 30, a finned joint (first joint) 70, and a pipe 100. Note that, although a configuration including the drain 30 is illustrated in the present embodiment, a configuration not including the drain 30 but requiring the finned joint 70 may be adopted. Specifically, the drainage structure 1 may include the metal cover 10, the catch basin 20, the finned joint 70, and a pipe 100.

[0018] (metal lid) The metal cover 10 is a metal cover having a plurality of holes. The plurality of holes may be of any shape as long as they do not prevent the inflow of rainwater. For example, a configuration in which a plurality of rectangular holes are arranged in a mesh pattern like a grating may be adopted. The metal cover 10 is supported by a catch basin 20, and rainwater flows into the catch basin 20 through the holes in the metal cover 10. In this embodiment, the outer shape of the metal cover 10 is rectangular in plan view, but is not limited to a rectangle, and may be a square, a polygon other than a square, a circle, or an ellipse.

[0019] (Drainage basin) As shown in FIG. 2, the catchment area 20 has an upper area 21, a lower area 22, and a height adjustment portion 23. The upper manhole 21 is a metal frame that supports the metal cover 10. The inside of the upper manhole 21 corresponds to the opening 20a of the drainage manhole 20, and the metal cover 10 is housed and disposed within this opening 20a. The upper box 21 has a side wall 41 and a lid mounting portion 42. The side wall 41 is a rectangular frame that surrounds the metal lid 10 on all four sides in a plan view. The lid mounting portion 42 is formed approximately perpendicular to the side wall 41 so as to extend from the lower edge of the side wall 41 toward the inside of the rectangular frame in a vertical cross-sectional view. The lid mounting portion 42 is a frame-shaped plate portion that forms a rectangular frame in a plan view. The metal lid 10 is supported on the upper surface of the lid mounting portion 42. In addition, the side wall 41 restricts the horizontal movement of the metal lid 10.

[0020] 3 and 4 show the lower manhole 22. Here, Fig. 3 is a vertical cross-sectional view of the lower manhole 22, and Fig. 4 is a cross-sectional view of the lower manhole 22 as viewed in the direction of the arrow BB in Fig. 3. The lower manhole 22 is a resin molded product made of, for example, FRP, and has a side wall 51, an upper manhole support portion 52, a tapered portion 53, and a pipe portion 54. The lower manhole 22 is not limited to being made of resin, and may be made of cast iron manufactured using a mold. The side walls 51 are rectangular frames that surround the upper section 21 on all four sides in a plan view. The upper manhole support portion 52 is a plate portion forming a rectangular frame in a plan view, and is arranged so as to overlap directly below the lid mounting portion 42 as shown in Fig. 2. As shown in Figs. 3 and 4, the upper manhole support portion 52 is formed approximately perpendicular to the side wall 51 so as to extend from the lower edge of the side wall 51 toward the inside of the rectangular frame in a vertical cross-sectional view. The upper manhole 21 is supported above this upper manhole support portion 52. As shown in Fig. 2, a height adjustment portion 23 is provided between the upper manhole support portion 52 and the lid mounting portion 42 to adjust the height position of the upper manhole 21 relative to the lower manhole 22.

[0021] As shown in FIGS. 3 and 4, the internal space of the narrowed portion 53 tapers downward, and the narrowed portion 53 is disposed directly below the upper manhole support portion 52 in a continuous manner. The narrowed portion 53 has four side walls 53a to 53d and a bottom wall 53e. Of these, the pair of side walls 53a, 53b facing each other have a constant width at the upper part, and the width at the lower part narrows toward the lower part, as shown in FIG. 3. Here, one side edge of each of the side walls 53a, 53b is aligned along the vertical direction, while the other side edge is bent at a midpoint in the height direction. That is, the other side edge is aligned along the vertical direction above the bent position, and is inclined so as to approach the pipe part 54 gradually below the bent position. Also, the pair of side walls 53a, 53b are inclined so that the distance between them narrows from their upper end edge toward their lower end edge, as shown in FIG. 4. Therefore, each inner wall surface of the pair of side walls 53a, 53b is inclined so as to approach the pipe part 54 from its upper end edge toward its lower end edge.

[0022] As shown in Fig. 4, the side wall 53c has an inverted trapezoid shape tapered from its upper edge toward its lower edge. As shown in Fig. 3, the side wall 53c is disposed along the vertical direction. Therefore, the inner wall surface of the side wall 53c is formed along the vertical direction. In a side view, the side wall 53d has an inverted trapezoidal shape tapered from its upper edge toward its lower edge. The side wall 53d is disposed opposite the side wall 53c. As shown in FIG. 3, the side wall 53d is bent at a midpoint in the vertical direction. That is, the upper portion of the side wall 53d is formed along the vertical direction, while the lower portion of the side wall 53d is gently inclined downward to approach the side wall 53c. That is, the inner wall surface of the side wall 53c is formed along the vertical direction at its upper portion, and is inclined downward to gradually approach the pipe portion 54 at its lower portion.

[0023] The bottom wall 53e is a plate portion having a rectangular shape in a plan view, to which the lower edges of the four side walls 53a to 53d are connected. The upper surface of the bottom wall 53e is connected to the lowest end positions of the inner wall surfaces of the side walls 53a to 53d. A circular opening (opening in the bottom wall) 53e1 having a drain axis O, which is a central axis line along the up-down direction, is formed at the center position of the bottom wall 53e in a plan view. The opening diameter d1 of the circular opening 53e1 is appropriately selected according to the amount of drainage, but since the use of the finned joint 70 improves the drainage performance, an opening diameter d1 of 100 mm or less can be adopted. When such a small diameter is adopted, construction can be performed in a small space, and the drainage structure 1 having excellent aesthetics can be obtained. The opening diameter d1 of the circular opening 53e1 may be, for example, 75 mm instead of 100 mm. On the other hand, the lower limit value of the opening diameter d1 can be, for example, 72 mm. In the following description, a case where the opening diameter of the circular opening 53e1 is 100 mm will be described as an example.

[0024] As shown in Figs. 3 and 4, the pipe section 54 is a circular pipe having a central axis in the vertical direction. The pipe section 54 is connected and arranged directly below the bottom wall 53e so as to be coaxial with the circular opening 53e1. The opening diameter d2 of the drainage port 54a of the pipe section 54 is equal to the opening diameter d1 of the circular opening 53e1 and is constant at each position from the upper end to the lower end. The opening diameter d2 of the pipe section 54 can be 100 mm, for example, in accordance with the opening diameter d1. The opening diameter of the pipe section 54 may be, for example, 75 mm (nominal diameter 75 A) instead of 100 mm (nominal diameter 100 A). On the other hand, the lower limit value of the opening diameter d2 can be, for example, 72 mm in accordance with the opening diameter d1. The pipe section 54 can be a resin pipe or a metal pipe, and is not particularly limited in terms of material. When a resin pipe is used as the pipe section 54, a VP pipe, a VU pipe, or the like can be used. On the other hand, when a metal pipe is used as the pipe section 54, a steel pipe, a stainless steel pipe, or the like can be used. The outer diameter of the pipe portion 54 can be, for example, 76 mm or more and 115 mm or less. The length of the pipe portion 54 may be less than 1000 mm, preferably less than 600 mm, and more preferably less than 500 mm, less than 400 mm, or less than 300 mm. 3 and 4, an example of the dimensions of each part of the lower box 22 can be exemplified as follows: L1 = 420 mm, L2 = 450 mm, L3 = 155 mm, L4 = 250 mm, and L5 = 300 mm. However, the dimensions of each part are not limited to these dimensions and may be appropriately changed as necessary.

[0025] The lower manhole 22 having the configuration described above is buried in the deck a, except for its upper end opening and the lower part of the pipe section 54, as shown in Fig. 2. The opening of the side wall 51 is not covered by the deck a and the pavement b, but is covered by a metal lid 10 fitted into the upper manhole 21. In addition, the lower part of the pipe section 54 is exposed to the outside from the underside of the deck a. As shown in Fig. 1, a slope i is formed on the side edge of the pavement b that is connected to the upper box 21, the slope i decreasing toward the upper end of the upper box 21. The height difference h due to this slope can be, for example, 5 mm to 20 mm. The deck a is a foundation structure formed by pouring concrete, and the pavement b is asphalt that forms a road surface laid on the top surface of the deck a. Although not shown in the figure, reinforcing steel bars that reinforce the periphery of the lower box 22 are buried in the deck a.

[0026] The height adjustment unit 23 shown in FIG. 2 adjusts the height position of the upper box 21 relative to the lower box 22. The height adjustment unit 23 has a bolt 61 and a nut 62. The bolt 61 is inserted into a through hole formed in the upper box support unit 52. The bolt 61 is disposed substantially perpendicular to the upper box support unit 52. The upper end of the bolt 61 abuts against the lower surface of the lid placement unit 42 of the upper box 21. The nut 62 is fixed on the upper box support unit 52 so as to be coaxial with the through hole. The bolt 61 is inserted into the nut 62. The height of the upper box 21 relative to the lower box 22 can be adjusted by adjusting the amount of threading of the bolt 61 into the nut 62. The height adjustment unit 23 may be provided on both the opposing long sides and the opposing short sides of the upper box support unit 52, or only on one of them.

[0027] (Finned joint / first joint) As shown in FIG. 5, a finned joint (first joint) 70 has a joint body 80 and a plurality of fins 90. The fitting body 80 is a cylindrical pipe having a central axis along the vertical direction, and has an inlet side joint portion 81 formed at the upper end, an outlet side joint portion 82 formed at the lower end, and a straight pipe portion 83 formed between them. The inlet side fitting portion 81 has a ring shape and is fixed by coaxially fitting onto the lower end of the pipe portion 54. The inner peripheral surface of the inlet side fitting portion 81 is slightly larger than the outer diameter of the lower end of the pipe portion 54, and is watertightly connected to the lower end of the pipe portion 54 via a sealing material (not shown). The outlet side fitting portion 82 also has a ring shape, and is fixed by fitting coaxially with the upper end of the pipe 100. The inner peripheral surface of the outlet side fitting portion 82 is slightly larger than the outer diameter of the upper end of the pipe 100, and is watertightly connected to the upper end of the pipe 100 via a seal material (not shown). Although the case of fitting from the outside is illustrated in this embodiment, it is not limited to fitting from the outside, and fitting from the inside may be used. In the case of fitting from the inside, it is possible to obtain an external shape in which the outer diameter at this connection position does not change in the pipe axis direction (no step), so that a piping structure 1 with excellent aesthetics can be obtained. The fact that fitting from the inside may be used is the same for each embodiment and each modified example described later.

[0028] The straight pipe section 83 is a cylindrical pipe arranged between the inlet side joint section 81 and the outlet side joint section 82 and coaxial with the inlet side joint section 81 and the outlet side joint section 82. The nominal diameters of the pipe section 54, the finned joint 70, and the piping 100 may be unified. In this case, the appearance when viewed from the outside is unified, so that the drainage structure 1 has excellent aesthetics. The inner diameter dimension of the straight pipe section 83 is also equal to the inner diameter dimension of the pipe section 54 and the inner diameter dimension of the piping 100. Therefore, the flow path extending vertically through the inside of each of the pipe section 54, the finned joint 70, and the piping 100 forms a cylindrical internal space having the same inner diameter at each position in the vertical direction, except for the portion where the fin 90 is arranged. That is, the flow path from the pipe section 54 through the finned joint 70 to the piping 100 is connected smoothly without any steps at the connection between the pipe section 54 and the finned joint 70 and at the connection between the finned joint 70 and the piping 100. The finned joint 70 may be integrated with the catch basin 20 by integrating the inlet side joint 81 with the pipe section 54.

[0029] In the present embodiment, in the joint body 80, the inlet side fitting 81 functions as an inlet side connection port provided at the end on the upstream side of the joint body 80. The outlet side fitting 82 functions as an outlet side connection port provided at the end on the downstream side of the joint body 80. In the illustrated example, the inlet side fitting 81 and the outlet side fitting 82 are both so-called sockets, but at least one of the inlet side fitting 81 and the outlet side fitting 82 may be a spigot. For example, both the inlet side fitting 81 and the outlet side fitting 82 may be spigots, or one of the inlet side fitting 81 and the outlet side fitting 82 may be a spigot and the other may be a spigot. When the inlet side connection port or the outlet side connection port is a socket, the outer diameter becomes locally large in the drainage structure 1. However, in this case, the outer diameter of the pipe itself connected to each connection port can be kept small. This can improve the overall appearance of the piping structure 1. This also applies to each of the embodiments and modified examples described below. In this embodiment, no other connection ports are provided in the joint body 80 between the inlet side joint portion 81 and the outlet side joint portion 82. In other words, the joint body 80 is not branched between the inlet side joint portion 81 and the outlet side joint portion 82, and no other pipes or joints (piping components) are connected between the inlet side joint portion 81 and the outlet side joint portion 82. As a result, drainage water from sources other than the catch basin 20 does not merge into the joint body 80. The joint body 80 may be, for example, a so-called socket.

[0030] The fins 90 are a number of blades formed integrally with the inner wall surface 83a of the straight pipe section 83 of the finned joint 70. In the case of this embodiment, four fins 90 are arranged at equal angular intervals (90° intervals) in the circumferential direction centered on the central axis of the straight pipe section 83. The number of fins 90 is not limited to four, and may be two, three, five or more, or even ten or more. Each fin 90 has the same shape and dimensions, and is also located at the same position along the pipe axis direction. That is, as shown in FIG. 5, all the fins 90 are isosceles triangles in a vertical cross section or a side view, and the bases are connected to the inner wall surface 83a of the straight pipe section 83 so as to be integral with each other. Thus, each fin 90 is formed so as to protrude from the inner wall surface 83a toward the pipe axis (central axis). A straight upper side 91, which is one of the equal sides of the isosceles triangle forming these fins 90, is disposed on the upstream side (vertical upper side) in the flow path, and a straight lower side 92, which is the other, is disposed on the downstream side (vertical lower side) in the flow path. These upper side 91 and lower side 92 are connected at a connection point 93. As another embodiment, for example, a shape and arrangement of a fin 90E described later with reference to FIG. 17 may be adopted.

[0031] Each fin 90 is arranged so as to face the other fin 90 at a circumferential position on the opposite side with the tube axis therebetween. In the case of this embodiment, as described above, when viewed along the tube axis, the four fins 90 are arranged at equal angular intervals, so that two pairs of fins 90 facing each other with the tube axis therebetween are arranged. Each upper edge 91 of the fins 90 forms a thin inclined surface that protrudes into the flow path. These inclined surfaces are connected to the inner wall surface 83a at the uppermost end position of the upper edge 91, and the protruding height from the inner wall surface 83a gradually increases from this uppermost end position toward the downstream side, and the protruding height from the inner wall surface 83a is greatest at the connection point 93. The thin inclined surface formed by the upper edges 91 arranged in this manner faces rainwater flowing down from the upstream side, and as this rainwater hits the inclined surface, it provides flow path resistance.

[0032] Each bottom side 92 of each fin 90 also forms a thin inclined surface that protrudes into the flow passage. These inclined surfaces are connected to the inner wall surface 83a at the lowest end position of the bottom side 92, and the protruding height from the inner wall surface 83a gradually increases from this lowest end position toward the upstream side, and the protruding height from the inner wall surface 83a is highest at the connection point 93. In other words, the inclined surfaces formed on each top side 91 and the inclined surfaces formed on each bottom side 92 have the same shape and dimensions, and the inclination directions are opposite at each side of the connection point 93 in the vertical direction.

[0033] The left side surface 94 and the right side surface 95 of each fin 90 are flat surfaces each having an isosceles triangle shape, and are parallel to each other. Therefore, each fin 90 has a constant plate thickness at each position from its upper end position to its lower end position. Since the left side surface 94 and the right side surface 95 enter the flow path, when rainwater passes through each fin 90, viscous resistance is applied to the rainwater by contacting the left side surface 94 and the right side surface 95. Therefore, both resistance caused by contact with the inclined surface formed by the upper side 91 and viscous resistance caused by contact with the left side surface 94 and the right side surface 95 are applied to the rainwater. Hereinafter, these two resistances may be collectively referred to as flow path resistance by the fin 90.

[0034] As shown in FIG. 5, all the fins 90 are fixed to the inner wall surface 83a so that their upper ends are located within 1000 mm vertically downward from the circular opening (opening in the bottom wall) 53e1 formed in the bottom wall 53e of the lower manhole 22. As a result, rainwater flowing into the finned joint 70 from the circular opening 53e1 through the pipe portion 54 begins to receive flow resistance when it hits each fin 90 located within 1000 mm vertically downward from the circular opening 53e1. This flow resistance creates a braking effect that reduces the flow rate of the rainwater that has flowed in. On the other hand, at a position downstream of the connection point 93, the direction of the inclined surface due to the lower side 92 is opposite to that of the upper side 91, and the protruding height from the inner wall surface 83a gradually decreases, so that excessive flow resistance is not continuously applied to the rainwater. In addition, the left side surface 94 and the right side surface 95 of each fin 90 can straighten the rainwater that tries to pass through while swirling. Therefore, each fin 90 provides an appropriate flow resistance to the rainwater to reduce the flow rate, and simultaneously rectifies the flow of the rainwater.

[0035] According to the above configuration, rainwater with a reduced flow rate temporarily accumulates in the flow path between the upper side 91 of each fin 90 and the circular opening 53e1, making it difficult for air to enter the rainwater flowing from the drain 30 into the circular opening 53e1, and it is possible to reliably induce the siphon effect. Moreover, since the rainwater after passing through each fin 90 has already been straightened by the left side surface 94 and the right side surface 95, it is drained smoothly without swirling.

[0036] However, the upper end of the fin 90 does not have to be located within 1000 mm vertically downward from the circular opening (opening in the bottom wall) 53e1 formed in the bottom wall 53e of the lower manhole 22, and the vertical distance between the upper end of the fin 90 and the opening 53e1 in the bottom wall may exceed 1000 mm. This distance may be 200 mm or more. If this distance is 200 mm or more, a certain water head difference is ensured, and the suction force due to the siphon phenomenon can be increased to allow rainwater to flow smoothly. These points are the same in each of the embodiments and modified examples shown below.

[0037] Furthermore, the length of the downspout continuing downstream of the finned joint 70 (the length of the vertical flow path including the piping 100), in other words, the length of the downspout below the lower end of the finned joint 70, may be 2000 mm or more. If the downspout length is less than 2000 mm, it may be difficult for the rainwater to be rectified, and the siphon phenomenon may be difficult to occur. This point is the same in each of the embodiments and modified examples shown below.

[0038] The shape of the fin 90 is not limited to the isosceles triangle shape illustrated in FIG. 5, but may be, for example, a right triangle shape as illustrated in FIG. 6, or a trapezoid shape as illustrated in FIG. 7. That is, in the case of the finned joint (first joint) 70A shown in FIG. 6, the fin 90A has a shape in which the lower half of the vertical direction from the connection point 93 in the fin 90 shown in FIG. 5 is removed. In this modification, instead of the lower side 92, a lower side 92A perpendicular to the inner wall surface 83a in a side view is provided. Therefore, in this modification, both the left side 94 and the right side 95 of each fin 90A are planes having a right-angled triangular shape connected to the inner wall surface 83a at one side, and are parallel to each other. Therefore, each fin 90A has a constant plate thickness at each position from its upper end position to its lower end position. Since the left side 94A and the right side 95A enter the flow path, when rainwater passes through each fin 90A, viscous resistance is applied to the rainwater by contacting the left side 94A and the right side 95A. Therefore, rainwater is subjected to both resistance caused by the inclined surface formed by the upper side 91 and viscous resistance caused by contact with the left side surface 94A and the right side surface 95A. Hereinafter, these two resistances may be collectively referred to as flow path resistance caused by the fins 90A. Other configurations are the same as those of the finned joint 70 described above, so the same components are denoted by the same reference numerals and their description will be omitted. Note that, in this modified example, the finned joint 70A may also be integrated with the catch basin 20 by integrating the inlet side joint portion 81 with the pipe portion 54.

[0039] In this modified example, all the fins 90A are fixed to the inner wall surface 83a so that their upper ends are located within 1000 mm vertically downward from the circular opening (opening in the bottom wall) 53e1 formed in the bottom wall 53e of the lower manhole 22. As a result, rainwater flowing into the finned joint 70 from the circular opening 53e1 through the pipe portion 54 begins to receive flow resistance by hitting each fin 90A located within 1000 mm vertically downward from the circular opening 53e1. This flow resistance creates a braking effect that reduces the flow rate of the rainwater that has flowed in. On the other hand, since there is no part protruding from the inner wall surface 83a at a position downstream of the lower side 92A, excessive flow resistance is not continuously applied to the rainwater. In addition, the rainwater that tries to pass through while swirling can be rectified by the left side surface 94A and the right side surface 95A of each fin 90A. Therefore, like the above-described fins 90, the fins 90A impart an appropriate flow resistance to the rainwater to reduce the flow rate, and simultaneously rectify the flow of the rainwater.

[0040] Therefore, according to the configuration of this modification, as in the first embodiment, rainwater with a reduced flow rate temporarily accumulates in the flow path between the upper side 91 of each fin 90A and the circular opening 53e1, making it difficult for air to enter the rainwater flowing from the drain 30 into the circular opening 53e1, and it is possible to reliably induce the siphon effect. Moreover, since the rainwater after passing through each fin 90A has already been straightened by the left side surface 94A and the right side surface 95A, it is drained smoothly without swirling.

[0041] Similarly, in the case of the finned joint (first joint) 70B shown in FIG. 7, the fin 90B has a rectangular shape that is long along the tube axis direction in the lower half of the vertical direction from the connection point 93 in the fin 90 shown in FIG. 5 in a side view or a vertical cross-sectional view. Therefore, in this modification, instead of the lower side 92, there is a side side 92B that is connected to the lower end of the upper side 91 and parallel to the tube axis, and a lower side 93B that is connected to the lower end of the side side 92B and connected perpendicularly to the inner wall surface 83a. Therefore, in this modification, both the left side surface 94B and the right side surface 95B of each fin 90B are flat surfaces having a trapezoid shape connected to the inner wall surface 83a at one side, and are parallel to each other. Therefore, the plate thickness of each fin 90B is constant at each position from its upper end position to its lower end position. Since the left side surface 94B and the right side surface 95B extend into the flow path, when the rainwater passes through each fin 90B, the rainwater is subjected to viscous resistance due to contact with the left side surface 94B and the right side surface 95B. Therefore, the rainwater is subjected to both resistance due to contact with the inclined surface formed by the upper side 91 and viscous resistance due to contact with the left side surface 94B and the right side surface 95B. Hereinafter, these two resistances may be collectively referred to as flow path resistance due to the fin 90B. Other configurations are the same as those of the finned joint 70, and therefore the same configurations are denoted by the same reference numerals and their description is omitted. In this modified example, the finned joint 70B may be integrated with the catch basin 20 by integrating the inlet side fitting portion 81 with the pipe portion 54.

[0042] In this modified example, all the fins 90B are fixed to the inner wall surface 83a so that their upper ends are located within 1000 mm vertically downward from the circular opening (opening in the bottom wall) 53e1 formed in the bottom wall 53e of the lower manhole 22. As a result, rainwater flowing into the finned joint 70 from the circular opening 53e1 through the pipe portion 54 begins to receive flow resistance by hitting each fin 90B located within 1000 mm vertically downward from the circular opening 53e1. This flow resistance creates a braking effect that reduces the flow rate of the rainwater that has flowed in. On the other hand, since there is no part protruding from the inner wall surface 83a at a position downstream of the lower side 93B, excessive flow resistance is not continuously applied to the rainwater. In addition, the rainwater that tries to pass through while swirling can be rectified by the left side surface 94B and the right side surface 95B of each fin 90B. Therefore, each fin 90B can provide an appropriate flow resistance to rainwater to reduce the flow rate and simultaneously rectify the rainwater, similar to each fin 90. In the present modification, each fin 90B is larger than each fin 90, and therefore can provide a higher flow resistance and rectification effect than each fin 90.

[0043] Therefore, according to the configuration of this modification, as in the first embodiment, rainwater with a reduced flow rate temporarily accumulates in the flow path between the upper side 91 of each fin 90B and the circular opening 53e1, making it difficult for air to enter the rainwater flowing from the drain 30 into the circular opening 53e1, and it is possible to reliably induce the siphon effect. Moreover, since the rainwater after passing through each fin 90B has already been straightened by the left side surface 94B and the right side surface 95B, it is drained smoothly without swirling.

[0044] As yet another modified example, the configuration shown in FIG. 8 can also be adopted. That is, in the first embodiment, the inner wall surface 83a is a straight pipe that is equidistant from the tube axis at each position in the tube axis direction, as shown in Fig. 5. In contrast, in this modification, a finned joint (first joint) 70C having a throttle opening 83p is used, as shown in Fig. 8. The finned joint 70C of this modification is provided with a throttle pipe section 83C instead of the straight pipe section 83. The throttle pipe section 83C is disposed at a position sandwiched between the inlet side joint section 81 and the outlet side joint section 82, and is a substantially cylindrical pipe coaxial with the inlet side joint section 81 and the outlet side joint section 82. The outer diameter of the throttle pipe section 83C is equal to the outer diameter of the pipe section 54 and the outer diameter of the piping 100. Therefore, when the pipe section 54, the finned joint 70C, and the piping 100 are viewed from the outside, the outer diameters of all of these are equal to one another, and therefore they have a uniform appearance.

[0045] The inner diameter of the throttle pipe section 83C is equal to the inner diameter of the pipe section 54 and the inner diameter of the pipe 100 at the upper and lower parts in the tube axis direction. On the other hand, at the center part in the tube axis direction, the part from the upper end to the throttle opening 83p is an inclined surface in which the inner diameter gradually narrows. In addition, at the center part in the tube axis direction, the part from the throttle opening 83p to the lower end is an inclined surface in which the inner diameter gradually widens. Therefore, inside the throttle pipe section 83C, when viewed from the upper end to the lower end, there is first a cylindrical internal flow path 83q, then an inverted truncated cone-shaped internal flow path 83r continuing from the lower end of the internal flow path 83q, then a truncated cone-shaped internal flow path 83s continuing from the lower end of the internal flow path 83r, and finally a cylindrical internal flow path 83t continuing from the lower end of the internal flow path 83s. In this way, when viewed from the upstream side to the downstream side along the pipe axial direction, the flow path is narrowed in the internal flow path 83r, narrowed to a minimum area at the position of the throttling opening 83p, and then expanded in the internal flow path 83s.

[0046] When the inner wall surface of the internal flow path 83r is viewed in a cross section including the tube axis as shown in FIG. 8, the inclination angle of the inner wall surface with respect to the tube axis is preferably greater than 0° and less than 80°, and more preferably greater than 5° and less than 45°. In addition, when comparing the lengths of the internal flow passages 83r and 83s along the pipe axis direction, it is preferable to make the length of the internal flow passage 83r longer than the length of the internal flow passage 83s. In this way, by avoiding a shape in which the internal flow passage 83r is suddenly narrowed, it is possible to reduce the possibility that the pressure loss when rainwater passes through it becomes too large, resulting in a decrease in drainage performance. In addition, when the flow passage cross-sectional area perpendicular to the pipe axis at the position of the inlet opening 83u is S1, and the flow passage cross-sectional area perpendicular to the pipe axis at the position of the throttle opening 83p is S2, it is preferable to satisfy the formula 0.7×S1≦S2≦0.9×S1. When the flow passage cross-sectional area S2 satisfies the lower limit of this formula, it is possible to avoid the possibility that too much rainwater accumulates and becomes difficult to drain. When the flow passage cross-sectional area S2 satisfies the upper limit of this formula, it is possible to avoid the possibility that the time until the siphoning phenomenon occurs becomes longer, or the possibility that the siphoning phenomenon occurs and does not occur repeatedly under normal rainfall intensity.

[0047] As described above, in the finned fitting 70C of this modified example, the flow path has an inlet opening 83u located at its uppermost end and having an opening area equal to the circular opening 53e1 of the bottom wall 53e, a throttle opening 83p located below the inlet opening 83u and communicating with the inlet opening 83u via an internal flow path (constriction inclined surface) 83r, and an outlet opening 83v located below the throttle opening 83p and communicating with the throttle opening 83p via an internal flow path 83s. In the internal flow passage 83r, the flow passage cross-sectional area is narrowed from the upstream to the downstream, so that flow passage resistance is imparted to the rainwater flowing therethrough, thereby making it possible to reduce the flow rate.

[0048] The finned joint 70C of this modification includes a plurality of fins 90C instead of the individual fins 90 described above. Each fin 90C is formed to protrude from the internal flow passages 83q, 83r toward the tube axis (center axis). In a side view or cross-sectional view, each fin 90C has an upper edge 91C located at the most upstream side, and a side edge 92C that is connected to the upper edge 91C and extends downward along the tube axis direction. In each fin 90C, in a side view or cross-sectional view, the side opposite the upper edge 91C is integrally connected to the internal flow passage 83r, and the side opposite the side edge 92C is integrally connected to the internal flow passage 83q.

[0049] Each fin 90C is arranged so as to face the other fins 90C at a circumferential position on the opposite side with the tube axis therebetween. In the case of this modification, four fins 90C are arranged at equal angular intervals when viewed along the tube axis, so that two pairs of fins 90C facing each other with the tube axis therebetween are arranged. Each top edge 91C of the fins 90C forms a thin inclined surface that protrudes into the flow path. The top end of each top edge 91C of the fins 90C is connected to the internal flow path 83q, and the protruding height from the internal flow path 83q gradually increases from the top end position toward the downstream side, and the protruding height from the internal flow path 83q is the highest at the connection position with the side edge 92C. The thin inclined surface of the top edge 91C arranged in this manner faces rainwater flowing down from the upstream side, and the rainwater hits the inclined surface, providing flow path resistance.

[0050] The left side surface 94C and the right side surface 95C of each fin 90C are flat surfaces having a rectangular shape and are parallel to each other. Therefore, the plate thickness of each fin 90C is constant at each position from its upper end position to its lower end position. Since the left side surface 94C and the right side surface 95C enter the flow path, when the rainwater passes through each fin 90C, viscous resistance is applied to the rainwater by contacting the left side surface 94C and the right side surface 95C. Therefore, both resistance caused by the inclined surface formed by the upper side 91C and viscous resistance caused by contact with the left side surface 94C and the right side surface 95C are applied to the rainwater. Hereinafter, these two resistances may be collectively referred to as flow path resistance by the fin 90C. Other configurations are the same as those of the finned joint 70, and therefore the same configurations are denoted by the same reference numerals and their description is omitted. In this modification, the finned joint 70C may be integrated with the catch basin 20 by integrating the inlet side joint portion 81 with the pipe portion 54.

[0051] In this modified example, all the fins 90C are fixed in the finned joint 70C so that their upper ends are located within 1000 mm vertically downward from the circular opening (opening in the bottom wall) 53e1 formed in the bottom wall 53e of the lower manhole 22. As a result, rainwater flowing into the finned joint 70C from the circular opening 53e1 through the pipe portion 54 begins to receive flow resistance by hitting each fin 90C located within 1000 mm vertically downward from the circular opening 53e1. This flow resistance creates a braking effect that reduces the flow rate of the rainwater that has flowed in. In addition, since the internal flow path 83r is narrowed so as to taper along the flow direction, the braking effect associated with this reduction in flow area is also applied to the rainwater.

[0052] Furthermore, the left side surface 94C and the right side surface 95C of each fin 90C can straighten the rainwater that tries to pass through while swirling. Thus, like each fin 90, each fin 90C can provide an appropriate flow resistance to the rainwater to reduce the flow rate and simultaneously straighten the rainwater. In the case of this modification, in addition to the flow resistance of each fin 90C, flow resistance due to the reduction in the flow area is also provided to the rainwater, so that it is possible to provide a higher flow resistance than in the first embodiment.

[0053] Therefore, according to the configuration of this modification, as in the first embodiment, rainwater with a reduced flow rate temporarily accumulates in the flow path between the upper side 91C of each fin 90C and the circular opening 53e1, making it difficult for air to enter the rainwater flowing from the drain 30 into the circular opening 53e1, and it is possible to reliably induce the siphon effect. Moreover, since the rainwater after passing through each fin 90C has already been straightened by the left side surface 94C and the right side surface 95C, it is drained smoothly without swirling.

[0054] 8 are arranged at outer positions to avoid overlapping with the throttle opening 83p when viewed from the upstream side to the downstream side along the tube axis. In other words, when the throttle opening 83p is viewed along the tube axis direction, the protruding height of each fin 90C is restricted so that the side edge 92C of each fin 90C does not enter the throttle opening 83p. This makes it possible to prevent the fin 90C from excessively interfering with rainwater about to pass through the throttle opening 83p and disrupting the flow.

[0055] As yet another modification, a finned joint (first joint) 70D shown in FIG. This modified example has a configuration similar to that of the modified example of FIG. 6, and further includes an inner tube 96D having an inverted truncated cone shape that tapers from the upstream side to the downstream side along the tube axis. The inner pipe 96D has an inner wall surface 96D1 and an outer wall surface 96D2 that taper downward. A circular inlet opening is formed at the upper end of the inner pipe 96D, and a circular outlet opening with a smaller diameter than the upper end is formed at the lower end of the inner pipe 96D. The outer wall surface 96D2 of the inner pipe 96D is fixed in a spaced state with respect to the inner wall surface 83a by a pair of fins 90A. As a result, two flow paths are formed in the finned joint 70D: a first flow path formed between the inner wall surface 83a and the outer wall surface 96D2, and a second flow path formed in the inner wall surface 96D1. Therefore, the rainwater that flows into the finned joint 70D branches into two, one that flows through the first flow path and one that flows through the second flow path. Of these, the rainwater flowing through the first flow path is decelerated due to flow path resistance caused by the reduction in the flow path area. In addition, the rainwater flowing through the second flow path is decelerated due to flow path resistance caused by hitting the pair of fins 90A.

[0056] In this modified example, all of the fins 90A are fixed in the finned joint 70D so that their upper ends are located within 1000 mm vertically downward from the circular opening (bottom wall opening) 53e1 formed in the bottom wall 53e of the lower manstool 22. Similarly, the upper end of the inner pipe 96D is fixed in the finned joint 70D so that it is located within 1000 mm vertically downward from the circular opening 53e1. As a result, rainwater flowing into the finned fitting 70D from the circular opening 53e1 through the pipe section 54 is slowed down by encountering the flow path resistance as described above as it passes through each fin 90A and the inner pipe 96D, which are located within 1000 mm vertically downward from the circular opening 53e1. In addition, the fins 90A can also straighten the rainwater that tries to pass through while swirling. Therefore, the finned joint 70D of this modification can provide an appropriate flow resistance to the rainwater to reduce the flow rate, and can simultaneously straighten the rainwater.

[0057] Therefore, according to the configuration of this modification, rainwater with a reduced flow rate temporarily accumulates in the flow paths between the first flow path and the second flow path and the circular opening 53e1, making it difficult for air to enter the rainwater flowing from the drain 30 into the circular opening 53e1, and it is possible to reliably induce the siphon effect. Note that, in this modification as well, the finned joint 70D may be integrated with the catch basin 20 by integrating the inlet side joint 81 with the pipe portion 54. Having now finished the explanation of the various modified examples of the finned joint 70, we will return to the explanation of the drainage structure 1 of the first embodiment.

[0058] (Drain) As shown in Fig. 10, the drain 30 is arranged coaxially so as to cover the circular opening 53e1 formed in the bottom wall 53e of the lower manhole 22. The drain 30 induces the occurrence of a siphon effect in rainwater drained from the lower manhole 22 to the pipe section 54. The drain 30 is a drainage member having a high drainage function for improving the drainage capacity of rainwater that has flowed into the drainage manhole 20. Note that the drain 30 according to this embodiment is only one example, and other types described later may be adopted as long as they are capable of rectifying the water flowing into the pipe section 54. The drain 30 is made of resin produced by injection molding using synthetic resin such as hard polyvinyl chloride resin, polycarbonate, ABS, AES, etc. Note that the drain 30 is not limited to being made of resin, and may be made of cast iron using a mold or SUS.

[0059] The drain 30 has a cover member 31 , a plurality of vertical ribs 33 , and a fitting portion 32 . The cover member 31 is a disk with the drain axis O along the vertical direction as its center line. Here, a disk is exemplified as the shape of the cover member 31, but the shape is not limited to this, and a funnel shape such as a funnel portion 33A in FIG. 11 described later may be used instead. In either case, any shape that covers a part or all of the circular opening 53e1 (drop hole) that is the drain port from above can be appropriately used. Although the cover member 31 can be omitted, it is easier to seal the water when draining and more likely to induce the siphon phenomenon, thereby improving the drainage performance. The vertical ribs 33 are fixed to the lower surface of the cover member 31 at equal angular intervals around the drain axis O. Although the vertical ribs 33 are exemplified as plate materials here, the present invention is not limited to this, and may be a rod (support leg) having a rectangular or circular cross section perpendicular to the longitudinal direction, as in the support part 32B in FIG. 12 described later. In any case, by providing the vertical ribs 33, foreign matter larger than the interval between the adjacent vertical ribs 33 can be removed from the rainwater. In addition, the flow of water that tends to swirl during drainage can be rectified. In the illustrated example, six vertical ribs 33 are provided, and these six vertical ribs 33 are provided at intervals of about 60 degrees around the drain axis O. However, the number and arrangement intervals of the vertical ribs 33 are not limited to this example.

[0060] Each of the vertical ribs 33 has the same shape as the others. Each of the vertical ribs 33 has an upper side 31a connected to the lower surface of the cover member 31, a lower side 31b disposed directly below the upper side 31a, and an inner side 31c and an outer side 31d connecting the upper side 31a and the lower side 31b. When the lower surface of the cover member 31 is viewed from the bottom, each of the upper sides 31a is disposed in a radial direction centered on the drain axis O. The inner sides 31c are connected to the ends of the upper sides 31a that are closest to the drain axis O. Conversely, the outer sides 31d are connected to the ends of the upper sides 31a that are farthest from the drain axis O. The inner sides 31c and the outer sides 31d are parallel to the drain axis O. Each of the inner sides 31c is longer than each of the outer sides 31d.

[0061] The upper side 31a, the inner side 31c, and the outer side 31d are all straight lines, but the lower side 31b is concavely curved. Therefore, when considering a surface circumscribing the lower sides 31b of each of the vertical ribs 33 arranged at equal angular intervals on a circumference, this surface forms a substantially inverted truncated cone shape tapering from top to bottom along the drain axis O. In this way, when each of the vertical ribs 33 is viewed collectively, each of the lower sides 31b tapers downward as a whole, so that it can be fitted into the circular opening 53e1 as shown in FIG. 2. Moreover, each of the lower sides 31b has the same shape and is arranged at equal distances from the drain axis O, so that it is possible to position each of the vertical ribs 33 so that the drain axis O and the central axis of the pipe portion 54 naturally coincide with each other by simply fitting the lower sides 31b of each of the vertical ribs 33 into the circular opening 53e1. In addition, when the drain 30 is attached in the lower manhole 22, the lower surface of the lid member 31 can be positioned at a predetermined height position above the bottom wall 53e of the lower manhole 22. In other words, the lid member 31 can be supported and fixed on the bottom wall 53e by each of the vertical ribs 33.

[0062] When the drain 30 is attached to the bottom wall 53e of the lower manhole 22, the cover member 31 is disposed so as to cover a part or the whole of the circular opening 53e1 in a plan view. Also, the area of ​​the cover member 31 in a plan view is larger than the opening area of ​​the circular opening 53e1. In this embodiment, the center of the cover member 31 and the center of the circular opening 53e1 coincide in the vertical direction, but when the cover member 31 and the circular opening 53e1 are both arranged at an angle, if the cover area of ​​the cover member 31 is the same as the opening area of ​​the circular opening 53e1, the circular opening 53e1 cannot be blocked when viewed from the vertical direction, and a gap through which air enters (an air core due to a vortex) is generated between the cover member 31 and the circular opening 53e1. Therefore, it is preferable to set the projected area of ​​the cover member 31 on a plane perpendicular to the vertical direction to be larger than the projected area of ​​the circular opening 53e1.

[0063] By fitting the drain 30 having the above-mentioned configuration into the circular opening 53e1 of the bottom wall 53e, six inflow openings 30a defined by the upper surface of the bottom wall 53e, the side surfaces of each vertical rib 33, and the lower surface of the cover member 31 are formed on the pipe portion 54. Each vertical rib 33 has a function of straightening the rainwater flowing into the pipe portion 54 from the inflow opening 30a. As described above, the cover member 31 suppresses air from mixing with the rainwater flowing into the pipe portion 54 from the inflow opening 30a. In addition, by combining with the provision of flow resistance by any of the finned joints 70 to 70D described above, the intake of air can be more reliably suppressed. In this way, by combining the drain 30 with the finned joints 70 to 70D, the rainwater can be straightened while suppressing the intake of air and then flowed into the pipe portion 54, thereby improving the drainage performance.

[0064] It is preferable to set the size of the cover member 31 and the height of each vertical rib 33 so that the total area of ​​all the inflow openings 30a is equal to or larger than the area of ​​the circular opening 53e1. In other words, when the diameter of the circular opening 53e1 is 100 mm, the total area of ​​all the inflow openings 30a is 7850 mm. 2 In addition, when the diameter of the circular opening 53e1 is 75 mm, the total area of ​​all the inflow openings 30a is 4416 mm or more. 2 More preferably, it is equal to or greater than this.

[0065] 10, a plurality of gripping ribs 35 protruding upward and arranged at equal angular intervals in the circumferential direction are fixed to the upper surface of the cover member 31. These gripping ribs 35 are portions that are gripped by an operator when fitting the drain 30 into the circular opening 53e1.

[0066] The fitting parts 32 are rod-shaped resin parts fixed to each of the vertical ribs 33, and have elasticity. The fitting parts 32 extend further directly downward from the lowest end position of each of the vertical ribs 33. When the drain 30 is attached, the side of the fitting parts 32 abuts on the inner peripheral surface of the pipe part 54. The fitting parts 32 are arranged in an annular shape when the cover member 31 is viewed from the bottom, and the diameter of the circumscribing surface that contacts the outer surface of these fitting parts 32 is slightly larger than the inner diameter dimension of the circular opening 53e1. Therefore, when the fitting parts 32 are fitted into the circular opening 53e1, the outer surface of the elastically deformed fitting parts 32 is pressed against the inner wall surface of the circular opening 53e1, so that a frictional force is generated between them, and the drain 30 can be reliably and easily fixed to the pipe part 54. Therefore, it does not easily come off even if it is subjected to an external force by rainwater. Conversely, the worker can remove the drain 30 from the bottom wall 53e of the lower manhole 22 by holding the gripping rib 35 and lifting the drain 30 upward against the frictional force. In this manner, the drain 30 of the present embodiment is separate from the catch basin 20 and can be attached to and detached from the catch basin 20.

[0067] The fitting portion 32 is one of the means for removably fixing the drain 30, and other configurations may be used. For example, although not shown, a configuration may be adopted in which the metal lid 10 and the drain 30 are connected by a hanging device such as a chain or a string. In this case, the drain 30 can be suspended and supported below the metal lid 10 by the hanging device. Therefore, simply removing the metal lid 10 allows the drain 30 to be removed at the same time, reducing the effort required for cleaning the drain 30 and improving maintainability. Alternatively, although not shown, a support may be further provided that is fixed inside the catch basin 20 and detachably supports the drain 30. In this case, the support can position and support the drain 30 at the upper end position of the pipe portion 54. At that time, since the support is fixed to the catch basin 20, the drain 30 can be fixed more reliably to prevent misalignment.

[0068] In this embodiment, the drain 30 is detachable from the catch basin 20, but the present invention is not limited to this configuration, and the drain 30 may be integrated with the catch basin 20. In this case, the installation of the drain 30 can be completed at the same time as simply installing the catch basin 20 during construction, thereby reducing construction costs. In addition, the relative position of the drain 30 with respect to the pipe section 54 does not shift, so the drainage capacity of the drain 30 can be more stably demonstrated.

[0069] The drain installed in the catch basin 20 may have a configuration other than the above-mentioned drain 30. For example, instead of the above-mentioned drain 30, the drain 30A in FIG. The drain 30A according to this modification is made of, for example, resin and has vanes 31A arranged at a plurality of positions in the circumferential direction around the drain axis O, and an inner cylindrical portion 32A and a funnel portion 33A connected to the radially inner ends of the vanes 31A. The inner cylindrical portion 32A has a vertically long cylindrical shape. The funnel portion 33A is an inverted truncated cone-shaped pipe material connected to and fixed integrally to the upper end of the inner cylindrical portion 32A, and the diameter of the pipe expands from the lower end to the upper end. When the drain 30 is attached to the bottom wall 53e of the lower manhole 22, the inner cylindrical portion 32A and the funnel portion 33A function as a lid member that partially or entirely covers the circular opening 53e1 in a plan view.

[0070] Each of the blades 31A is a flat plate having the same shape. Each blade 31A has an upper side 31Aa extending horizontally at equal angular intervals from the outer periphery of the upper end of the funnel portion 33A, an outer side 31Ab extending downward from the outermost end of the upper side 31Aa, and a lower side 31Ac extending from the lower end of the outer side 31Ab toward the drain axis O. Each lower side 31Ac has a curved shape concave upward in side view.

[0071] The fitting parts 32 are fixed to the lower sides 31Ac of the blades 31A. That is, the fitting parts 32 are fixed to the blades 31A so as to extend further downward from the lowest end position of each blade 31A and to abut the inner peripheral surface of the pipe part 54. Therefore, in this modification, when the funnel part 33A is viewed from the bottom, the fitting parts 32 are arranged in a ring shape, and the diameter of the circumscribing surface that contacts the outer surface of these fitting parts 32 is slightly larger than the opening diameter d2 of the pipe part 54. Therefore, by fitting the fitting parts 32 into the circular opening 53e1 of the bottom wall 53e, the drain 30A can be detachably fixed to the pipe part 54. Like the drain 30 of the above embodiment, the drain 30A may be supported by being suspended from the metal cover 10 by the hanging tool, or may be detachably fixed to the inside of the catch basin 20 by the supporting tool. Alternatively, the drain 30A may be integrated with the catch basin 20.

[0072] By attaching the drain 30A described above to the bottom wall 53e in the lower manhole 22, a plurality of openings are formed that communicate with the circular opening 53e1. That is, a plurality of openings are formed that are defined by the outer peripheral surface of the funnel portion 33A, the side surfaces of the blades 31A, and the upper surface of the bottom wall 53e. In addition, an opening is also formed that passes through the inner tube portion 32A and the funnel portion 33A in the vertical direction. In this drain 30A as well, rainwater is straightened by passing through the openings formed between the side surfaces of the blades 31A before flowing into the pipe section 54. In addition, by combining the provision of flow path resistance by any of the finned joints 70 to 70D described above, air intake can be more reliably suppressed. In this way, by combining the drain 30A with the finned joints 70 to 70D, rainwater can be straightened while suppressing air intake before flowing into the pipe section 54, improving drainage performance.

[0073] As another example of the drain to be installed in the catch basin 20, for example, a drain 30B shown in FIG. The drain 30B of this modified example is formed, for example, from resin, and has a stepped cylindrical main body 31B, four support portions 32B fixed onto the main body 31B, and a funnel portion 33B fixedly positioned on the main body 31B by these support portions 32B.

[0074] An annular plate portion 31B1 is formed on the upper part of the main body 31B. Rainwater flows into an opening formed in the center of this plate portion 31B1. The upper end opening of the main body 31B is connected to the opening of the plate portion 31B1. The main body 31B is a cylinder with a central axis (pipe axis) along the vertical direction, and has a stepped structure in which the inner diameter of the upper part is relatively larger than the inner diameter of the lower part. The drain 30B can be installed in the catch basin 20 by fitting the main body 31B into the circular opening 53e1 shown in FIG. 2 until the lower surface of the plate portion 31B1 abuts against the upper surface of the bottom wall 53e. Each support portion 32B stands upward from the opening of the plate portion 31B1, and a funnel portion 33B is fixed to each upper end of each support portion 32B. The support portions 32B are arranged at 90° intervals in the circumferential direction around the tube axis. The funnel portion 33B has an inverted truncated cone shape. Just below the opening formed at the upper end of the funnel portion 33B, another opening is formed coaxially.

[0075] In the drain 30B having the above-described configuration, surrounding rainwater is taken in mainly through four trapezoidal openings defined by the edge of the opening of the plate portion 31B1, the side edges of the support portions 32B, and the outer periphery of the funnel portion 33B, and then flows into the pipe portion 54. At that time, by combining the provision of flow resistance by any of the above-described finned joints 70 to 70D, the intake of air can be more reliably suppressed. In this way, by combining the drain 30B with the finned joints 70 to 70D, the rainwater can be straightened while suppressing the intake of air and then flowed into the pipe portion 54, thereby improving the drainage performance.

[0076] (Plumbing) The piping 100 shown in Fig. 2 is a drain pipe extending in the vertical direction, and its upper end is watertightly connected to the outlet side fitting portion 82 of the finned joint 70 via a seal material (not shown). The opening diameter of the piping 100 is the same as the opening diameter d2 of the pipe portion 54. Therefore, the opening diameter of the piping 100 can be 100 mm, for example. However, the opening diameter of the piping 100 is not limited to 100 mm, and 72 mm, 75 mm, 125 mm, 150 mm, or the like may be adopted. A resin pipe or a metal pipe can be used as the piping 100, and there is no particular limitation on the material. When a resin pipe is used as the piping 100, a VP pipe, a VU pipe, or the like can be used. On the other hand, when a metal pipe is used as the piping 100, a steel pipe, a stainless steel pipe, or the like can be used. The outer diameter of the piping 100 can be, for example, 76 mm or more and 165 mm or less. When a steel pipe is used instead of the VP pipe as the piping 100, 80 mm (nominal diameter 80A) may be used instead of the above 75 mm. In this case, the inner diameters of the circular opening 53e1 and the pipe portion 54 are also set to the same 80 mm in accordance with the diameter of the piping 100. Although not shown in the figure, the downstream side of the pipe 100 is connected to other pipes (horizontal pipes and vertical pipes) via joints. The water that flows down through the pipe 100 flows through the joints and other pipes, and then is drained into a public sump or the like.

[0077] (skeleton 1) The main points 1 of the first embodiment and the various modifications described above will be summarized below. (1) As illustrated in FIG. 2, the drainage structure 1 according to this embodiment includes a catchment basin (water collection section) 20 that takes in rainwater, and a finned joint (first joint) 70 that is disposed below the bottom wall 53e of the catchment basin 20. As illustrated in FIG. 5, the finned joint 70 includes a joint body 80 having an inner wall surface 83a that forms a flow path therein that leads to the circular opening 53e1 of the bottom wall 53e, and a plurality of fins 90 that have an upper end relatively upstream and a lower end relatively downstream and are disposed in the flow path along the periphery of the pipe axis of the joint body 80. As illustrated in FIG. 5, each fin 90 is provided on the inner wall surface 83a so that the upper end of each fin 90 is located within 1000 mm vertically downward from the circular opening 53e1 of the bottom wall 53e.

[0078] According to the drainage structure 1 described in (1) above, rainwater flowing into the catch basin 20 is drained to the finned joint 70 through the circular opening 53e1 formed in the bottom wall 53e. The rainwater passing through the flow path of the finned joint 70 is subjected to flow path resistance by the fins 90 whose upper ends are located within 1000 mm vertically downward from the circular opening 53e1, so that the rainwater tends to temporarily accumulate in the space upstream (above) the fins 90. This temporary accumulation of rainwater can suppress the intake of air at the circular opening 53e1 and suppress the generation of vortexes, so that it is possible to effectively induce the siphon phenomenon at the circular opening 53e1 of the bottom wall 53e of the catch basin 20 and improve the drainage performance. In addition, the rainwater passing through the flow path of the finned joint 70 tries to pass while swirling, but since it is rectified by the fins 90 extending along the pipe axis, it is smoothly drained after passing the position of the fins 90. In addition, since the fins 90 are positioned at a depth that is not too far back when viewed from the circular opening 53e1, debris in the finned joint 70 can be easily accessed and removed from the circular opening 53e1 of the catch basin 20. This makes it possible to provide the drainage structure 1 with high maintainability while maintaining a configuration that enhances drainage performance.

[0079] (2) As illustrated in Figure 8, in the drainage structure 1 described in (1) above, the flow path may have an inlet opening 83u located at its uppermost end and having an opening area equal to that of the circular opening 53e1 of the bottom wall 53e, and a throttling opening 83p located below the inlet opening 83u and communicating with the inlet opening 83u via an internal flow path (constriction inclined surface) 83r. In the case of the drainage structure 1 described in (2) above, rainwater that has flowed into the inlet opening 83u of the flow path flows into the throttle opening 83p while contracting along the internal flow path 83r. By contracting the rainwater in this way, it is possible to impart flow path resistance associated with the contraction to the rainwater in addition to the flow path resistance due to the fin 90C. This makes it possible to more effectively form a temporary pool of rainwater on the upstream side of the finned joint 70C, thereby more reliably inducing the siphon phenomenon.

[0080] (3) As also shown in FIG. 8, in the drainage structure 1 described in (2) above, when the flow path in the finned fitting 70C is viewed along the pipe axis, the fin 90C may be arranged at an outer position that avoids overlap with the throttling opening 83p. In the case of the drainage structure 1 described in (3) above, the fins 90C can be prevented from excessively interfering with and disrupting the flow of rainwater that is about to pass through the throttling opening 83p, which has the smallest opening area in the flow path within the finned joint 70.

[0081] [Second embodiment] Hereinafter, a second embodiment of the present invention will be described with reference to Fig. 13 and Fig. 14. Fig. 13 is a view showing the second embodiment, and is a vertical cross-sectional view of a drainage structure 2 for an eaves gutter. Fig. 14 is a view showing a main part of the drainage structure 2, and is an enlarged view of part D in Fig. 13. In this embodiment, a case will be described in which the finned joint (first joint) 70 described in the first embodiment with reference to Fig. 5 is applied to a gutter drainage structure 2 (rainwater drainage system 2) attached to the eaves of a building. Also, in this embodiment, the drain 30 described in the first embodiment with reference to Fig. 10 is used as a drain member. Details of the finned joint 70 and the drain 30 have already been described in the first embodiment, so duplicated explanations will be omitted below. In this embodiment, a configuration including the drain 30 is illustrated as an example, but a configuration not including the drain 30 and instead requiring the finned joint 70 may be adopted.

[0082] As shown in Fig. 13, the folded plate roof 101 has a configuration in which peaks 103 and valleys 104 made of metal plates are formed on the upper end of a building wall 102 and are formed in a continuous, alternating corrugated shape. Fig. 13 is a partial cross-sectional view of the eaves end portion and wall 102 of the folded plate roof 101, in which a rectangular frame-shaped eaves gutter support 106 is fixed by a plurality of mounting bolts 105 that vertically penetrate the metal plate that constitutes the peaks 103 of the eaves end. The eaves gutter 107 is suspended and supported by the eaves gutter support 106. The tip of the eaves gutter 107 is capped, and the gutter is formed using members such as joints and supports that connect the eaves gutter 107 together. The eaves gutter support 106 is structured to support the bottom surface of the eaves gutter 107, but it may also be structured to suspend the side plate 107B of the eaves gutter 107. The drain 30 is attached to the bottom of the eaves gutter 107. The downspout 112 is connected to the lower part of the drain 30 via the outer tube 142, the finned joint 70, and two elbow pipes 110 and 111. The downspout 107 is supported below the eaves of the folded plate roof 101, so it can receive rainwater flowing down from the eaves. The downspout 107 also includes a valley gutter. The downspout 112 is supported vertically by a plurality of mounting brackets (not shown) attached at several points above and below along the wall 102, and is connected to a drainage channel (not shown) buried in the ground near the building so that rainwater can be drained. The downspout 112 is constructed using members such as joints and supports that connect the downspouts 112 to each other.

[0083] The folded plate roof 101 shown in Figure 13 has a slight downward roof slope from the right side of the page to the left side of the page, and the end of the folded plate roof 101 on the left side of the page is the eaves edge. The eaves edge extends from the front to the back of the page in Figure 13, and multiple eaves gutter supports 106 are fixed at predetermined intervals along the extended eaves edge, and these multiple eaves gutter supports 106 support eaves gutters 107. Figure 13 is a partial cross-sectional view showing only a portion of the eaves edge, so only one eaves gutter support 106 and one eaves gutter 107 are shown. The eaves gutter 107 is supported by the eaves gutter support 106 and is suspended almost horizontally. The eaves gutter 107 comprises a bottom plate 107A and side plates 107B, 107B formed to rise upward from the left and right ends of the bottom plate 107A. The front-to-back direction of the paper in FIG. 13 is the length direction of the eaves gutter 107, and the left-to-right direction of the paper in FIG. 13 is the width direction of the eaves gutter 107. As shown in FIG. 14, a circular opening 107A1 is formed in the center of the width of the bottom plate 107A, which serves as an inlet for rainwater flowing in through the drain 30. An outer cylinder portion 142 is fixed to the underside of the bottom plate 107A so as to be coaxial with the circular opening 107A1.

[0084] The eaves gutter 107 is an extrusion molded product made of synthetic resin such as rigid polyvinyl chloride resin, ABS, or AES. The material for forming the eaves gutter 107 can be set arbitrarily and is not limited to synthetic resin, and may be, for example, a metal molded product. More specifically, the eaves gutter 107 may be made of, for example, an olefin resin such as a polyethylene resin or a polypropylene resin, or a thermoplastic polyester resin having excellent heat durability. The eaves gutter 107 may also be made of a metal plate, and may be made of, for example, a hot-dip galvanized steel plate, a painted hot-dip galvanized steel plate, a hot-dip zinc or aluminum alloy plated steel plate, a painted hot-dip zinc or aluminum alloy plated steel plate, a hot-dip aluminum plated steel plate, a polyvinyl chloride coated metal plate, a cold-rolled stainless steel plate, a painted stainless steel plate, a titanium plate or titanium alloy plate, a highly weather-resistant rolled steel plate, an asphalt or resin coated steel plate, an aluminum alloy plate, or the like. The eaves gutter 107 has a bottom width of 100 mm or more and 300 mm or less, and a height of 90 mm or more and 400 mm or less, and may be applied to a large-diameter eaves gutter that can carry rainwater at a flow rate of, for example, 4 liters / sec or more and 20 liters / sec or less.

[0085] The outer tube 142 has a circular internal flow passage in its upper part that expands in diameter toward the top, and a circular internal flow passage in its lower part whose inside diameter is constant at each position in the pipe axial direction. These internal flow passages communicate with a circular opening 107A1 (opening) formed in the bottom plate (bottom wall) 107A of the eaves gutter 107. 14, the inlet side mating portion 81 of the finned joint 70 is watertightly and coaxially connected to the lower end of the outer tube portion 142 via a sealing material (not shown). Furthermore, the upper end of the elbow pipe 110 is watertightly and coaxially connected to the outlet side mating portion 82 of the finned joint 70 via a sealing material (not shown). Therefore, rainwater that flows into the eaves gutter 107 flows into the outer cylinder 142 through the circular opening 107A1 formed in the bottom plate 107A of the eaves gutter 107. Furthermore, the rainwater that flows down inside the outer cylinder 142 flows downward inside the finned joint 70, and at that time, the flow resistance is imparted and the flow is rectified by each fin 90. Then, the rainwater rectified by the finned joint 70 flows into the elbow pipe 110, and is further drained through the elbow pipe 111 and downspout 112 connected downstream.

[0086] 14, the fins 90 are provided on the inner wall surface 83a so that the upper end of each fin 90 is located within 1000 mm vertically downward from a circular opening 107A1 formed in the bottom plate (bottom wall) 107A of the eaves gutter 107. In other words, the vertical position of the finned joint 70 is determined so that the upper end of each fin 90 is located within 1000 mm vertically downward from the circular opening 107A1. As a result, rainwater that flows into the finned joint 70 begins to experience flow resistance as it hits each fin 90 located within 1000 mm vertically downward from the circular opening 107A1. This flow resistance creates a braking effect that reduces the flow rate of the rainwater that flows in. In addition, the rainwater that tries to pass through while swirling can be straightened by the left side surface 94 and the right side surface 95 of each fin 90. Therefore, each fin 90 provides an appropriate flow resistance to the rainwater to reduce the flow speed, and at the same time, straightens the rainwater.

[0087] Therefore, according to the configuration of this embodiment, as in the first embodiment, rainwater with a reduced flow rate temporarily accumulates in the flow path between the upper side 91 of each fin 90 and the circular opening 107A1, making it difficult for air to enter the rainwater flowing from the drain 30 into the circular opening 107A1, and it is possible to reliably induce the siphon effect. Moreover, since the rainwater after passing through each fin 90 has already been straightened by the left side surface 94 and the right side surface 95, it is drained smoothly without swirling.

[0088] (Gist 2) The main feature 2 of the second embodiment described above will be summarized below. (1) As illustrated in FIG. 13, the drainage structure 2 according to this embodiment includes an eaves gutter (water collection section) 107 that takes in rainwater, and a finned joint (first joint) 70 arranged below the bottom plate 107A of the eaves gutter 107. As illustrated in FIG. 14, the finned joint 70 includes a joint body 80 having an inner wall surface 83a that forms a flow path therein leading to a circular opening 107A1 of the bottom plate 107A, and a plurality of fins 90 that have an upper end relatively upstream and a lower end relatively downstream and are arranged in the flow path along the periphery of the pipe axis of the joint body 80. As illustrated in FIG. 14, each fin 90 is provided on the inner wall surface 83a so that the upper end of each fin 90 is located within 1000 mm vertically downward from the circular opening 107A1 of the bottom plate 107A.

[0089] According to the drainage structure 2 described in (1) above, rainwater flowing into the eaves gutter 107 is drained to the finned joint 70 through the circular opening 107A1 formed in the bottom plate 107A. The rainwater passing through the flow path of the finned joint 70 is subjected to flow path resistance by the fins 90 whose upper ends are located within 1000 mm vertically downward from the circular opening 107A1, so that the rainwater tends to temporarily accumulate in the space upstream (above) the fins 90. This temporary accumulation of rainwater can suppress the intake of air at the circular opening 107A1 and suppress the generation of vortexes, so that the siphon phenomenon at the circular opening 107A1 can be effectively induced to improve the drainage performance. In addition, the rainwater passing through the flow path of the finned joint 70 tries to pass while swirling, but since the flow is rectified by the fins 90 extending along the pipe axis, it is smoothly drained after passing the position of the fins 90. In addition, since the fins 90 are positioned at a depth that is not too far back when viewed from the circular opening 107A1, debris inside the finned joint 70 can be easily removed by accessing it from the circular opening 107A1. This makes it possible to provide a drainage structure 2 that is easy to maintain while maintaining a configuration that enhances drainage performance.

[0090] (2) The finned joint 70 of the second embodiment is an example, and the finned joints 70A to 70D according to the modified examples described in the first embodiment may be used instead of this finned joint 70. For example, as in the finned joint 70C illustrated in Fig. 8, the internal flow path may have an inlet opening 83u located at the uppermost end thereof and having an opening area equal to that of the circular opening 53e1 of the bottom wall 53e, and a throttle opening 83p located below the inlet opening 83u and communicating with the inlet opening 83u via an internal flow path (constricted flow inclined surface) 83r.

[0091] (3) In this second embodiment, when the finned joint 70C illustrated in Figure 8 is adopted, the fins 90 may be arranged in an outer position that avoids overlap with the throttling opening 83p when the flow path in the finned joint 70C is viewed along the pipe axis. In this case, it is possible to prevent the fins 90 from excessively interfering with the rainwater that is about to pass through the throttle opening 83p having the smallest opening area in the flow path inside the finned joint 70C, thereby preventing the flow from being disturbed.

[0092] [Third embodiment] Hereinafter, a third embodiment of the present invention will be described with reference to Fig. 15. Fig. 15 is a side view showing a vertical cross section of a part of a drainage structure 3 having a cleaning port. In this embodiment, rather than placing the finned joint (first joint) directly below the catch basin, the finned joint 70 is placed below a cleaning port 241 provided midway through the drainage pipeline, as shown in FIG. 15. In this embodiment, a configuration including the drain 30 is illustrated as an example, but a configuration not including the drain 30 and instead requiring the finned joint 70 may be adopted.

[0093] The drainage structure 3 has a drainage basin (water collection section) 210, the drain 30, an elbow pipe 220, a first drainage pipe (second piping) 230, a second drainage pipe (third piping) 240, the finned fitting 70, and a third drainage pipe 250. The catch basin 210 is a square basin having a square bottom wall 211 with a circular opening 211a formed in the center, four side walls 212 formed upward from the four sides of the bottom wall 211, and a metal wire mesh lid 213 that closes the rectangular opening defined by the upper sides of these side walls 212. The bottom wall 211 and the four side walls 212 form a container, the upper opening of which is closed by the wire mesh lid 213. However, since the wire mesh lid 213 has a mesh-like opening, rainwater can be taken into the catch basin 210 through this opening. Before flowing into the circular opening 211a, the taken-in rainwater is rectified by a drain 30 fitted coaxially into the circular opening 211a.

[0094] The elbow pipe 220 is a pipe material having one end watertightly connected to the circular opening 211a of the bottom wall 211, and changes the flow direction of rainwater from vertically downward to horizontally. That is, it takes in rainwater that has flowed downward on the page in FIG. 15 and changes the flow direction to the right side on the page. The first drain pipe 230 is a straight pipe having a pipe axis along the horizontal direction, one end of which is watertightly connected to the elbow pipe 220, and the other end of which is watertightly connected to the side of the second drain pipe 240. Therefore, rainwater flowing in from the elbow pipe 220 flows horizontally through the first drain pipe 230 and then into the second drain pipe 240.

[0095] The second drain pipe 240 is a straight pipe having a pipe axis along the vertical direction, and the tip of the first drain pipe 230 is watertightly connected to an opening formed on the side of the second drain pipe 240. A cleaning port 241 is provided at the upper end of the second drain pipe 240. This cleaning port 241 is closed by an openable lid 242, but when removing garbage accumulated in the flow path, it is possible to open the lid 242 and access the inside. The lower end of the second drain pipe 240 is watertightly and coaxially connected to the inlet side fitting portion 81 of the finned joint 70. The cleaning port 241 and the lid 242 similar to those of this embodiment may be applied to the drainage structure 2 described in FIG. 13. The third drain pipe 250 is a straight pipe having a pipe axis along the vertical direction, and its upper end is watertightly and coaxially connected to the outlet side joint 82. The lower end of the third drain pipe 250 is connected to a piping (not shown), and drains rainwater that flows through the drain box 210, elbow pipe 220, first drain pipe 230, second drain pipe 240, finned joint 70, and third drain pipe 250 in this order.

[0096] 15, the fins 90 are provided on the inner wall surface 83a so that the upper ends of the fins 90 are located within 1000 mm vertically downward from the circular opening 211a formed in the bottom wall 211. In other words, the vertical position of the finned joint 70 is determined so that, in terms of height relative to the circular opening 211a in the vertical direction, the fins 90 are below the circular opening 211a and the upper ends of the fins 90 are located within 1000 mm. As a result, rainwater that has flowed into the finned joint 70 begins to experience flow resistance as it hits each of the fins 90. This flow resistance creates a braking effect that reduces the flow rate of the rainwater that has flowed in. In addition, the rainwater that tries to pass through while swirling can be straightened by the left side surface 94 and the right side surface 95 of each fin 90. Therefore, each fin 90 provides an appropriate flow resistance to the rainwater to reduce the flow speed, and at the same time, straightens the rainwater.

[0097] Therefore, according to the configuration of this embodiment, as in the first embodiment, rainwater with a reduced flow rate temporarily accumulates in the flow path between the upper side 91 of each fin 90 and the circular opening 211a, making it difficult for air to enter the rainwater flowing from the drain 30 into the circular opening 211a, and it is possible to reliably induce the siphon effect. Moreover, since the rainwater after passing through each fin 90 has already been straightened by the left side surface 94 and the right side surface 95, it is drained smoothly without swirling.

[0098] In FIG. 15, if the length of the downspout continuing downstream of the finned joint 70 (the length of the vertical flow path including the third drain pipe 250) is 2000 mm or more, preferably 3000 mm or more, it is easier to induce the siphon phenomenon in the drain 30, which is preferable from the viewpoint of improving drainage performance. Therefore, the length from the outlet of the drain 30 to the elbow pipe 220 may be kept within 1000 mm. In this case, the height position of the finned joint 70 can be increased, and therefore it is easier to ensure that the length of the downspout connecting to its lower end is 3000 mm. This configuration allows smooth drainage without excessive pressure loss.

[0099] (skeleton 3) The main feature 3 of the third embodiment described above will be summarized below. (1) The drainage structure 3 (rainwater drainage system 3) according to this embodiment includes a catch basin 210 that takes in rainwater, and a finned joint 70 that is disposed below a bottom wall 211 of the catch basin 210. The finned joint 70 includes a joint body 80 having an inner wall surface 83a that forms a flow path therein that leads to a circular opening 211a in the bottom wall 211, and a plurality of fins 90 that have an upper end relatively on the upstream side and a lower end relatively on the downstream side and are disposed in the flow path along the periphery of the pipe axis of the joint body 80. Each fin 90 is provided on the inner wall surface 83a so that the upper end of each fin 90 is located at a position shifted horizontally from the circular opening 211a in the bottom wall 211 and within 1000 mm vertically downward.

[0100] According to the drainage structure 3 described in (1) above, rainwater that flows into the catch basin 210 passes through the circular opening 211a formed in the bottom wall 211, and then flows into the finned joint 70 via the elbow pipe 220, the first drain pipe 230, and the second drain pipe 240. The rainwater passing through the flow path of the finned joint 70 is subjected to flow path resistance by the fins 90 whose upper ends are located within 1000 mm vertically downward from the circular opening 211a, so that the rainwater tends to temporarily accumulate in the space from the circular opening 211a to the upstream side of each fin 90. This temporary accumulation of rainwater suppresses the intake of air at the circular opening 211a and suppresses the generation of vortexes, so that it is possible to effectively induce the siphon phenomenon at the circular opening 211a and improve the drainage performance. Furthermore, rainwater passing through the flow path of the finned joint 70 tends to swirl as it passes through, but because the fins 90 extending along the pipe axis rectify the flow, it is smoothly drained after passing the position of the fins 90. In addition, because the fins 90 are located at a depth position close to the cleaning port 241, debris inside the finned joint 70 can be easily accessed and removed from the cleaning port 241. This makes it possible to provide a drainage structure 3 that is easy to maintain while maintaining a configuration that enhances drainage performance.

[0101] (2) The finned joint 70 of the third embodiment is one example, and the finned joints 70A to 70D according to the modified examples described in the first embodiment may be used instead of this finned joint 70. For example, as in the finned joint 70C illustrated in Fig. 8, the internal flow path may have an inlet opening 83u located at the uppermost end thereof and having an opening area equal to that of the circular opening 211a of the bottom wall 211, and a throttling opening 83p located below the inlet opening 83u and communicating with the inlet opening 83u via an internal flow path (constricted flow inclined surface) 83r.

[0102] (3) In this third embodiment, when the finned joint 70C illustrated in Figure 8 is adopted, the fins 90 may be arranged in an outer position that avoids overlap with the throttling opening 83p when the flow path in the finned joint 70C is viewed along the pipe axis.

[0103] (4) The drainage structure 3 of the third embodiment further includes a first drainage pipe 230 connected to the circular opening 211a of the drainage basin 210 and extending laterally, and a second drainage pipe 240 having a cleaning port 241 formed at its upper end, a pipe end of the first drainage pipe 230 connected to its side, and extending downward. The upper end of the finned joint 70 is connected to the lower end of the second drainage pipe 240. This makes it possible to provide a drainage structure 3 that is easy to maintain while maintaining a configuration that enhances drainage performance as described above.

[0104] [Fourth embodiment] Hereinafter, a fourth embodiment of the present invention will be described with reference to Fig. 16. Fig. 16 is a perspective view showing a drainage structure 4 (rainwater drainage system 4) in which a vertical joint (second joint) and the above-mentioned finned joint (first joint) 70 are connected in this order directly below a square box. In this embodiment, a configuration including the drain 30 is illustrated as an example, but a configuration not including the drain 30 and instead requiring the finned joint 70 may be adopted.

[0105] The drainage structure 4 of this embodiment has a drainage basin (water collection portion) 310, the drain 30, a vertical joint 320, the finned joint 70, and a vertical gutter 330. The catch basin 310 is a square basin having a square bottom wall 311 with a circular opening 311a formed in the center, four side walls 312 formed upward from the four sides of the bottom wall 311, and a metal wire mesh lid 313 that closes the rectangular opening defined by the upper sides of these side walls 312. The bottom wall 311 and the four side walls 312 form a container, the upper opening of which is closed by the wire mesh lid 313. However, since the wire mesh lid 313 has a mesh-like opening, rainwater can be taken into the catch basin 310 through this opening. Before flowing into the circular opening 311a, the taken-in rainwater is rectified by a drain 30 fitted coaxially into the circular opening 311a.

[0106] 16, the fins 90 are provided on the inner wall surface 83a so that the upper ends of the fins 90 are located within 1000 mm vertically downward from the circular opening 311a formed in the bottom wall 311. In other words, the vertical position of the finned joint 70 is determined so that, in terms of height relative to the circular opening 311a in the vertical direction, the fins 90 are below the circular opening 311a and the upper ends of the fins 90 are located within 1000 mm. As a result, rainwater that has flowed into the finned joint 70 begins to encounter flow resistance as it hits each fin 90. This flow resistance creates a braking effect that reduces the flow rate of the rainwater that has flowed in, just like in the first embodiment. Also, each fin 90 similarly provides a flow straightening effect.

[0107] Therefore, according to the configuration of this embodiment, as in the first embodiment, rainwater with a reduced flow rate temporarily accumulates in the flow path between the upper side 91 of each fin 90 and the circular opening 311a, making it difficult for air to enter the rainwater flowing from the drain 30 into the circular opening 311a, and it is possible to reliably induce the siphon effect. Moreover, since the rainwater has already been rectified after passing through each fin 90, it is drained smoothly without swirling.

[0108] The configuration of the downstream side of the downpipe 330 is not particularly limited. For example, a junction 340 may be provided on the downstream side of the downpipe 330, as in a drainage structure 4A according to a modification shown in Figs. 18 and 19. Fig. 18 is a perspective view showing a modification of the fourth embodiment, showing a drainage structure 4A in which a drain pipe cover 360 is provided on the downstream side of the downpipe 330. Fig. 14 is a vertical cross-sectional view showing an example of a drain pipe cover 360 provided in the drainage structure 4A.

[0109] As shown in FIG. 18, the junction 340 is, for example, a so-called Tee. The junction 340 may be, for example, a DV joint defined in JIS K 6739:2016, such as DT (90° Y, 90° Y with different diameters), LT (90° large bend Y, 90° large bend Y with different diameters), WLT (90° large bend both Y, 90° large bend both Y with different diameters), Y (45° Y, 45° Y with different diameters), etc. A first end of a horizontal branch pipe 340A is connected to the junction 340. A second end of the horizontal branch pipe 340A is connected to, for example, another catchment basin (not shown) different from the catchment basin 310. Drainage water (rainwater) from the other catchment basin (horizontal branch pipe 340A) is joined to the junction 340. In this case, the ratio of the drainage from the vertical gutter 330 to the drainage from the horizontal branch pipe 340A may be, for example, (2:1 or less). In this case, the length of the downspout below the lower end of the finned joint 70 may be 2000 mm or more. In this case, the length of the downspout below the lower end of the finned joint 70 may mean, for example, the length from the lower end of the finned joint 70 to the upper end of the branch pipe at the junction 340. In other words, the length from the lower end of the finned joint 70 to the upper end of the branch pipe at the junction 340 may be 2000 mm or more. If this length is less than 2000 mm, rainwater may not be rectified easily, and the siphon phenomenon may not occur easily.

[0110] A downspout 350 is further provided downstream of the junction 340. As shown in FIG.

[0111] The drain pipe cover 360 is provided between the vertical gutter 350 and the underground buried piping 365 in the drainage structure 4A. As shown in Fig. 19, the drain pipe cover 360 is provided with a first connection port (receiving port) 361 for inserting the vertical gutter 350, a second connection port (insertion port) 362 for inserting the underground buried piping 365, an overflow hole 363 provided on the side of the second connection port 362, and a cover part 364 for covering the underground buried piping 365. Note that the structure of the drain pipe cover 360 is an example and is not limited to this form.

[0112] The first connection port 361 is connected to the downpipe 350. The downpipe 350 is inserted into the first connection port 361. The downpipe 350 may expand or contract depending on the temperature of the installation location. In order to absorb this deformation, the downpipe 350 and the first connection port 361 are not fixed by adhesive or the like, but are connected by, for example, only insertion, with a margin in the inner diameter of the first connection port 361 relative to the outer diameter of the downpipe 350. The insertion margin of the downpipe 350 into the first connection port 361 may be 150 mm or more. The first connection port 361 may be, for example, cylindrical or square tubular.

[0113] The second connection port 362 is connected to the underground buried pipe 365. The second connection port 362 is inserted into the underground buried pipe 365. Rainwater flowing down from the downspout 350 flows down through the inner space of the drain pipe cover 360 and flows down into the underground buried pipe 365 through the second connection port 362. The second connection port 362 may be cylindrical or square tubular. An overflow hole 363, which will be described later, may be provided on a side surface of the second connection port 362. In this case, it is preferable to set an insertion margin so that the inner wall of the underground buried pipe 365 and the overflow hole 363, which will be described later, do not interfere with each other.

[0114] The overflow hole 363 is a hole provided in a side surface of the columnar portion of the second connection port 362. For example, the overflow hole 363 may be provided in a rectangular shape and in a circumferential direction along the side surface of the columnar portion of the second connection port 362, as shown in FIG. Moreover, the overflow hole 363 may be located closer to the first connection port 361 than the axial center of the second connection port 362 so as not to interfere with the underground buried piping 365. Moreover, the lower end of the overflow hole 363 in the axial direction may be located above the upper end of the underground buried piping 365. The overflow hole 363 has the function of allowing drainage water that does not completely flow into the underground buried pipe 365 during heavy rain or the like to escape from the inner space of the drain pipe cover 360 to the outside as escape drainage water.

[0115] The cover portion 364 is provided so as to cover the second connection port 362 and the overflow hole 363 on the ground side. The upper end of the cover portion 364 is located between the first connection port 361 and the second connection port 362, and extends horizontally from the outer circumferential surfaces of the first connection port 361 and the second connection port 362 outward in the direction perpendicular to the axis. The lower end of cover portion 364 spreads in the axial direction from the edge of the upper end toward the lower end of second connection port 362, and covers second connection port 362. In addition, the lower end of cover portion 364 may be located axially above or below the lower end of second connection port 362, and may be located above or below the ground. By using such a shape, the drainage water flowing out from the overflow hole 363 is prevented from spreading onto the ground.

[0116] The underground buried pipe 365 is connected to the lower end (second connection port 362) of the drain pipe cover 360. The underground buried pipe 365 is a pipe buried in the ground. In the illustrated example, the underground buried pipe 365 includes a first elbow 366, a connection pipe 367, and a short pipe 368. The connecting pipe 367 is disposed underground along a horizontal plane, for example, with a drainage gradient. The first elbow 366 connects the lower end of the drain pipe cover 360 and a first end of the connecting pipe 367. In the illustrated example, a short pipe 368 is provided between the drain pipe cover 360 and the first elbow 366, but the short pipe 368 may be omitted. Note that this underground buried pipe 365 is just one example, and other specific examples of the underground buried pipe 365 will be described later.

[0117] As described above, the drain pipe cover 360 of this modified example is provided with the overflow hole 363, so that when rainwater attempts to overflow from between the downpipe 350 and the drain pipe cover 360, it flows out from the overflow hole 363. This prevents rainwater from overflowing between the downpipe 350 and the drain pipe cover 360, allowing efficient drainage.

[0118] In addition, when the drainage capacity of the underground buried pipe 365 is insufficient and wastewater backs up during heavy rain, etc., water can be drained through the overflow hole 363 provided in the second connection port 362, thereby preventing water from overflowing between the vertical gutter 350 and the first connection port 361 of the drain pipe cover 360, or from overflowing from the confluence 340, for example. Moreover, by preventing water from overflowing as described above, it is possible to prevent flooding as well as the damage to the scenery caused by overflowing water. However, the hole 363 does not have to be provided.

[0119] In addition, the drain pipe cover 360 connects the vertical pipe 350, which expands and contracts depending on temperature and the like, to the underground buried pipe 365 in a manner that does not affect the expansion and contraction of the vertical pipe 350. By connecting in this manner, rainwater can be efficiently transported to the underground drain pipe.

[0120] (skeleton 4) The main feature 4 of the fourth embodiment described above will be summarized below. (1) The drainage structure 4 according to this embodiment includes a catch basin 310 that takes in rainwater, a vertical joint 320 that is arranged below a bottom wall 311 of the catch basin 310, and a finned joint 70. The finned joint 70 includes a joint body 80 having an inner wall surface 83a that forms an internal flow path that leads to a circular opening 311a in the bottom wall 311, and a plurality of fins 90 that have an upper end relatively on the upstream side and a lower end relatively on the downstream side and are arranged in the flow path along the periphery of the pipe axis of the joint body 80. Each fin 90 is provided on the inner wall surface 83a so that the upper end of each fin 90 is located within 1000 mm vertically downward from the circular opening 311a in the bottom wall 311.

[0121] (2) The finned joint 70 of the fourth embodiment is one example, and the finned joints 70A to 70D according to the modified examples described in the first embodiment may be used instead of this finned joint 70. For example, as in the finned joint 70C illustrated in Fig. 8, the internal flow path may have an inlet opening 83u located at the uppermost end and having an opening area equal to that of the circular opening 311a of the bottom wall 311, and a throttle opening 83p located below the inlet opening 83u and communicating with the inlet opening 83u via an internal flow path (constricted flow inclined surface) 83r.

[0122] (3) In this fourth embodiment, when the finned joint 70C illustrated in Figure 8 is adopted, the fins 90 may be arranged in an outer position that avoids overlap with the throttling opening 83p when the flow path in the finned joint 70C is viewed along the pipe axis.

[0123] (4) As described above, the drainage structure 4 of the fourth embodiment includes the vertical joint 320 as a second joint that connects between the circular opening 311a of the catch basin 310 and the inlet opening of the finned joint 70. Furthermore, the drainage structure 4 has a vertical gutter 330 as a first pipe that is connected to the outlet opening of the finned joint 70 and extends downward. In this embodiment, the rainwater passing through the flow path of the finned joint 70 is subjected to flow path resistance by the fins 90 whose upper ends are located within 1000 mm vertically downward from the circular opening 311a, so that the rainwater tends to temporarily accumulate in the space from the circular opening 311a to the upstream side of each fin 90. This temporary accumulation of rainwater suppresses the intake of air at the circular opening 311a and suppresses the generation of vortexes, so that it is possible to effectively induce the siphon phenomenon at the circular opening 311a and improve the drainage performance. Furthermore, rainwater passing through the flow path of the finned joint 70 tends to swirl as it passes through, but because the fins 90 extending along the pipe axis rectify the flow, the water is smoothly drained after passing the position of the fins 90. In addition, each fin 90 is located within 1000 mm vertically downward from the circular opening 311a, so that debris inside the finned joint 70 can be easily removed. This makes it possible to provide a drainage structure 4 that is easy to maintain while maintaining a configuration that enhances drainage performance.

[0124] [Fifth embodiment] Hereinafter, a fifth embodiment of the present invention will be described with reference to Fig. 20. Fig. 20 is a diagram showing the fifth embodiment, and is a vertical cross-sectional view including a partial side view showing a drainage structure 5 applied to a flat roof.

[0125] As shown in Fig. 20, the drainage structure 5 is installed in a building with a flat roof. A flat roof is a planar roof having a wall (for example, a parapet P) standing on the outer periphery of the roof. The drainage structure 5 is disposed outside the building.

[0126] The drainage structure 5 moves rainwater that falls on the roof R of the building to the vicinity of the ground and drains it, for example, into a sewer pipe. The number of drainage structures 5 installed on a building may be one, or two or more. When a building has, for example, two drainage structures 5, the two drainage structures 5 may be disposed near opposing sides of the building.

[0127] The drainage structure 5 includes a water collection section 410, a horizontal draw pipe 420, a joint 430, a vertical pipe 440, and a finned joint 70. Specifically, the drainage structure 5 includes a water collection section 410 arranged on the roof R, a horizontal draw pipe 420 connected to the water collection section 410, a vertical pipe 440 arranged downstream of the horizontal draw pipe 420, a joint 430 connecting the horizontal draw pipe 420 and the vertical pipe 440, and a finned joint 70 connected to the vertical pipe 440.

[0128] The water collection section 410 may be, for example, a horizontal drain. When the water collection section 410 is a horizontal drain, a recess may be provided in the portion of the roof R where the water collection section 410 is provided. By providing the water collection section 410 (horizontal drain) in such a recess, water collection becomes easier. In the drainage structure 5 shown in FIG. 20, the water collection section 410 opens horizontally from the parapet P toward the roof R, the bottom wall of the water collection section 410 faces horizontally, and the opening 410a formed in the bottom wall opens horizontally. However, the water collection section 410 (the opening 410a formed in the bottom wall of the water collection section 410) may open upward from the slab of the roof R.

[0129] The horizontal draw pipe 420 is connected to the water collecting section 410 arranged on the roof R. The horizontal draw pipe 420 connected to the water collecting section 410 is arranged along the horizontal direction and is connected to a joint 430 described later. The horizontal draw pipe 420 may have a water gradient from the upstream side to the downstream side. If the horizontal draw pipe 420 has a water gradient from the upstream side to the downstream side, it is possible to prevent water from accumulating inside the horizontal draw pipe 420.

[0130] The joint 430 has a main body 431, an upstream connection part 432, a downstream connection part 433, a cleaning port 434, and a lid 435. The joint 430 may be a so-called Tee. The cleaning port 434 and the lid 435 may not be included.

[0131] The main body 431 is a cylinder extending in the vertical direction. The upstream connection part 432 protrudes from a side surface of the main body 431. The cleaning port 434 is the upper end of the main body 431. The cover 435 is detachably attached to the cleaning port 434. When the cleaning port 434 and the main body 431 are not provided, the upper end of the main body 431 may be closed. The downstream connection part 433 is provided at the lower end of the main body 431.

[0132] The upright pipe 440 is connected to the downstream connection portion 433 of the joint 430. The upright pipe 440 connected to the downstream connection portion 433 of the joint 430 is disposed along the vertical direction. The finned joint 70 is connected to the lower end of the upright pipe 440. In this embodiment as well, the upper ends of all of the fins 90 are located within 1000 mm vertically downward from the opening 410a formed in the bottom wall of the water collecting section 410. With regard to the distance between the upper ends of the fins 90 and the opening 410a, the starting point (upper end position) on the opening 410a side of this distance can be, for example, the portion of the opening 410a that is located at the lowest position.

[0133] The drainage structure 5 may be provided with a band (not shown). The band is fixed to the wall of the building. The band may be attached to, for example, the joint 430, the upright pipe 440, or the finned joint 70. The band can, for example, suppress vibration of the attached piping component during drainage. Furthermore, when the band loosely supports the upright pipe 440, etc., it can also suppress stress concentration by allowing expansion and contraction (for example, thermal expansion and contraction) of the upright pipe 440, etc. When the band is provided to the joint 430 or the upright pipe 440, it is preferable that the band is attached within 300 mm above the upper end of the finned joint 70. Furthermore, the upright pipe 440 may be omitted, and the joint 430 and the finned joint 70 may be directly connected.

[0134] While the embodiments and various modifications of the drainage structure of the present invention have been described above, these may be combined as appropriate. Furthermore, the drainage structure of the present invention may be one that is provided in a building that is installed outdoors, and may be applied not only to bridges and civil engineering structures, but also to houses, buildings, etc.

[0135] In the finned joint 70 shown in FIG. 5, the fins 90 are integrated with the straight pipe section 83, but the present invention is not limited to this configuration, and each fin 90 may be detachable from the straight pipe section 83. Similarly, in the finned joint 70A shown in FIG. 6, the fins 90A are integrated with the straight pipe section 83, but the present invention is not limited to this configuration, and each fin 90A may be detachable from the straight pipe section 83. Similarly, in the finned joint 70B shown in FIG. 7, the fins 90B are integrated with the straight pipe section 83, but the present invention is not limited to this configuration, and each fin 90B may be detachable from the straight pipe section 83. Similarly, in the finned joint 70C shown in FIG. 8, the fins 90C are integrated with the straight pipe section 83, but the present invention is not limited to this configuration, and each fin 90C may be detachable from the choke pipe section 83C. Similarly, in the finned joint 70D shown in Figure 9, the fins 90A and the inner pipe 96D are integrated with the straight pipe section 83, but this configuration is not limited to this, and the fins 90A and the inner pipe 96D may be freely attached and detached to the straight pipe section 83.

[0136] As described above, by making each of the fins 90-90D detachable, it is possible to further improve the ease of maintenance, such as cleaning. A specific example of a detachable fin will be described with reference to FIG. 17. FIG. 17 is a perspective view showing a modification of the first embodiment, as viewed from a vertical section including the tube axis. In this modification, the fins are attached in a socket type, and are detachable from the lower end of the joint body. The shape of the fins and the arrangement angle of the fins with respect to the tube axis direction are also changed.

[0137] A finned joint (first joint) 70E according to this modified example has a joint body 80E and a plurality of fins 90E. The fitting body 80E has a straight pipe section 83 which is a cylindrical pipe having a pipe axis along the vertical direction, the inlet side joint section 81 formed integrally with the upper end of the straight pipe section 83, and an outlet side joint section 82E which is coaxially connected to the lower end of the straight pipe section 83.

[0138] A finned ring 90E1 having fins 90E formed on its inner circumferential surface is integrally connected to the outlet-side mating portion 82E of this modified example via a connecting portion 90E2. The finned ring 90E1 has an upstream edge 90E1a located relatively upstream, a downstream edge 90E1b located relatively downstream, a contraction section 90E1c connecting the upstream edge 90E1a and the downstream edge 90E1b, and a plurality of the fins 90E arranged at equal angular intervals in the circumferential direction around the pipe axis on the inner surface of the contraction section 90E1c.

[0139] Both the upstream edge 90E1a and the downstream edge 90E1b are annular flange portions, and have an outer diameter close to the inner diameter of the inner peripheral surface of the straight pipe section 83. Therefore, the upstream edge 90E1a and the downstream edge 90E1b can contact the inner wall surface 83a of the straight pipe section 83 without any gap. When viewed in a cross section including the pipe axis, the inner peripheral surface of the upstream edge 90E1a is gradually thicker from the upstream side toward the downstream side. Therefore, although the upstream edge 90E1a is inserted into the inner wall surface 83a, it does not create an excessively large step with respect to the inner peripheral surface of the straight pipe section 83, and allows the flow of rainwater passing through here to pass smoothly without being disturbed. The downstream edge 90E1b is smoothly connected to the upper end of the connection portion 90E2 without creating an excessively large step. Therefore, the downstream edge 90E1b allows the rainwater passing through it to pass smoothly without disturbing the flow. In addition, the downstream edge 90E1b forms an annular gap between itself and the inner peripheral surface of the outlet side fitting portion 82E, and the lower end of the straight pipe portion 83 is fitted watertightly into this annular gap.

[0140] The contraction section 90E1c has an arch-like shape in a cross section including the tube axis, with the upper half from the upstream side to a midway point in the tube axis direction forming a contraction flow path, and the lower half from the midway point toward the downstream side in the tube axis direction forming an expansion flow path. That is, in the upper half, the inner diameter of the circular opening as viewed in the direction along the tube axis gradually decreases from the upstream side to the downstream side, and reaches a minimum inner diameter at the boundary with the lower half. Then, in the subsequent lower half, the inner diameter of the circular opening as viewed in the direction along the tube axis gradually increases from the minimum inner diameter as viewed from the upstream side to the downstream side, and becomes equal to the inner diameter of the connecting section 90E2 at the boundary with the connecting section 90E2.

[0141] Each fin 90E is a linear projection having an upper end 90Ea located at the most upstream side in the tube axis direction and a lower end 90Eb located at the most downstream side in the tube axis direction. In this modification, when viewed along the tube axis direction, the lower end 90Eb is located at a position slightly shifted laterally from directly below the upper end 90Ea. Therefore, each fin 90E is arranged at an incline so that a straight line connecting the upper end 90Ea and the lower end 90Eb intersects with the tube axis when it is superimposed. Then, between adjacent fins 90E, an inclined flow path is formed along a direction that intersects with the tube axis when it is superimposed.

[0142] When viewed in a cross section perpendicular to a straight line connecting the upper end 90Ea and the lower end 90Eb, each fin 90E has a substantially triangular cross-sectional shape at each position on the straight line. The height of the triangular cross section gradually increases from the upper end 90Ea to the center of the straight line, and then gradually decreases from the center of the straight line to the lower end 90Eb. In addition, the width dimension when these fins 90E are viewed opposite each other gradually increases from the upper end 90Ea to the center of the straight line, and then gradually narrows from the center of the straight line to the lower end 90Eb. In other words, each fin 90E is thickest at the center in the tube axis direction, and gradually becomes thinner from this center toward the upper end 90Ea. Similarly, each fin 90E gradually becomes thinner from the center toward the lower end 90Eb. Furthermore, when each fin 90E is viewed in a cross section including a straight line connecting the upper end 90Ea and the lower end 90Eb and along the thickness direction of the wall portion of the contraction portion 90E1c, it forms a convex arch shape that conforms to the inner surface of the contraction portion 90E1c. Since each of the fins 90E has the above-mentioned shape, it is possible to gradually increase the flow resistance applied to rainwater along the pipe axis direction.

[0143] According to the configuration described above, when rainwater passes through each of the fins 90E and the finned ring 90E1, both flow contraction and flow straightening occur simultaneously, allowing the rainwater to be drained smoothly. In addition, each fin 90E is arranged so that the upper end 90Ea of each fin 90E is located within 1000 mm vertically downward from the circular opening 53e1 (FIG. 2) of the bottom wall 53e. As a result, rainwater flowing into the finned joint 70E begins to encounter flow resistance caused by hitting each fin 90E and resistance caused by the contraction formed by the inner circumferential surface of the contraction portion 90E1c. This flow resistance creates a braking effect that reduces the flow speed of the rainwater that has flowed in, as in the first embodiment. Also, each fin 90E similarly provides a rectifying effect.

[0144] Therefore, according to the configuration of this modification, as in the first embodiment, rainwater with a reduced flow rate temporarily accumulates in the flow path between the upper side of each fin 90E and the circular opening 53e1, making it difficult for air to enter the rainwater flowing from the drain 30 into the circular opening 53e1, and it is possible to reliably induce the siphon effect. Moreover, since the rainwater has already been rectified after passing through each fin 90E, it is drained smoothly without swirling. In addition, the finned ring 90E1 on which each fin 90E is formed is integrated with the outlet side fitting portion 82E and a socket-type structure is adopted in which it is coaxially fitted into the lower end of the straight pipe portion 83, making it possible to easily install and replace each fin 90E, as well as to perform maintenance such as cleaning. The socket-type configuration including the fins 90E and the finned ring 90E1 according to this modified example may be applied to each of the above embodiments.

[0145] Returning to the description of the other modified example of the first embodiment shown in FIG. 2 is separate from the catch basin 20, the present invention is not limited to this configuration, and the finned joint 70 may be integrated with the catch basin 20. The same applies to the other finned joints 70A, 70B, 70C, and 70D, and they may be integrated with the catch basin 20. 2 is configured to be directly connected to the pipe portion 54 of the catch basin 20, the configuration is not limited thereto, and the finned joint 70 and the pipe portion 54 of the catch basin 20 may be coaxially connected with a short pipe (not shown) interposed between them. The same is true for the other finned joints 70A, 70B, 70C, and 70D, which may be connected to the pipe portion 54 of the catch basin 20 with a short pipe (not shown) interposed between them.

[0146] Furthermore, as a joint to be combined with each of the finned joints 70, 70A, 70B, 70C, and 70D of each embodiment, a joint described in JIS K6739 can be suitably used. For example, large bent elbows with bending angles of 90°, 60°, and 45° may be used as the elbows 110, 111, and 220 shown in Figs. 13 and 15. Alternatively, VUS sockets may be used instead of the elbows 110, 111, and 220. Alternatively, elbows with different diameters, each having a different diameter at the receiving port at each end, may be combined. Furthermore, fittings such as Tee, DT, and LT may be combined. Alternatively, the elbow may be combined with an increaser that expands the diameter of the flow path upstream.

[0147] Furthermore, the drainage structures 1, 2, 3, 4, 4A, and 5 according to each embodiment and each modified example may be connected to a water collection basin 580 on the downstream side as shown in Fig. 21 and Fig. 22. Fig. 21 is a vertical cross-sectional view including a side view showing a first example of a connection form between the drainage structures 1, 2, 3, 4, 4A, and 5 according to each embodiment of the present invention and the water collection basin 580. Fig. 22 is a vertical cross-sectional view including a side view showing a second example of a connection form between the drainage structures 1, 2, 3, 4, 4A, and 5 according to each embodiment of the present invention and the water collection basin 580. In the following description, in each of the drainage structures 1, 2, 3, 4, 4A, and 5, a portion connected to a water collection basin 580 (FIG. 21) or an underground buried piping 590 (FIG. 22) is referred to as a pipe 520. The pipe 520 is a so-called downspout, and can be said to be the portion located most downstream in the downspout. In the illustrated example, a lower end 520b of the pipe 520 is connected to the water collection basin 580 (FIG. 21) or the underground buried piping 590 (FIG. 22). The lower end 520b of the pipe 520 may be located below the ground G.

[0148] 21 , a downstream lower end 520b of pipe 520 is connected to the ground G, and is connected to a known water collection basin (drainage mechanism) 580 buried in the ground. Water collection basin 580 is connected to a drainage structure such as a sewer pipe 584 via a connecting pipe 582. Water collection basin 580 has a larger width (inner diameter) than pipe 520. Lower end 520b of pipe 520 is located above connecting pipe 582 within water collection basin 580. In this first example, an elbow (not shown) may be provided at the lower end 520b of the pipe 520. Examples of this elbow include a so-called 45° elbow and a 90° elbow (a 90° large bend elbow). By connecting an elbow to the lower end 520b, the direction in which the wastewater flows changes. This reduces the force of the wastewater flowing down into the water collection basin 580, making it less likely for water to splash in the water collection basin 580.

[0149] 22, an underground buried pipe 590 is connected to a downstream lower end 520b of a pipe 520. In the illustrated example, the underground buried pipe 590 includes an elbow 541, a straight pipe 542, an expansion joint 544, a straight pipe 546, and an elbow 547. In the underground buried pipe 590, it is preferable that each of these components (piping components) is connected in this order.

[0150] One of the sockets of an elbow 541 is connected to the lower end 520b on the downstream side of the pipe 520. The elbow 541 changes the direction of the flow of wastewater by approximately 90°. The elbow 541 may be one elbow (90° elbow) as in the illustrated example, or may be a combination of two or more elbows. When the elbow 541 is a combination elbow, the elbow 541 may include two elbows (45° elbows). In this case, the curved pipe portions of each of the two elbows are bent at approximately 45° in side view. By combining two elbows, for example, an axis passing through the socket of one elbow and an axis passing through the socket of the other elbow intersect at 90° in side view, forming an elbow 541 that is bent at 90° as a whole.

[0151] The other socket of the elbow 541 is connected to the upstream end of the straight pipe 542. The downstream end of the straight pipe 542 is connected to the upstream socket of the expansion joint 544. The upstream end of the straight pipe 546 is connected to the downstream socket of the expansion joint 544. The diameter of the hollow part of the straight pipe 546 is larger than the diameter of the hollow part of the straight pipe 542. The straight pipe 546 penetrates the water collection basin 580 in the middle of the longitudinal direction. The downstream end of the straight pipe 546 is disposed inside the water collection basin 580. The upstream socket of the elbow 547 is connected to the downstream end of the straight pipe 546. In the illustrated example, the elbow 547 is a so-called 45° elbow, but may be a 90° elbow. In the illustrated example, the downstream socket of the elbow 547 opens diagonally downward, but may open directly downward.

[0152] 22, rainwater that flows down pipe 520 toward the downstream side flows down while bending at elbow 541, and flows downstream approximately horizontally through straight pipe 542, expansion joint 544, and straight pipe 546. Furthermore, the rainwater is discharged downstream, i.e., downward, from elbow 547 and stored in catchment basin 580. 22, the underground buried pipe 590 includes an elbow 541, a straight pipe 542, an expansion joint 544, and a straight pipe 546, thereby appropriately suppressing the flow rate and drainage amount of rainwater that flows down the pipe 520 at high speed. Note that the presence of the expansion joint 544 makes it difficult for the flow of rainwater to be obstructed, but the expansion joint 544 is not necessary. 22, an elbow 547 is provided at the downstream end, and the receiving port of the elbow 547 opens downward, thereby preventing the rainwater W from colliding with the side wall of the water collection basin 580, thereby preventing the rainwater from being splashed upward by the side wall of the water collection basin 580 and spouting onto the ground. When the receiving port opens obliquely downward as in the elbow 547 shown in FIG. 22, for example, the straight pipe 542, the expansion joint 544, and the straight pipe 546 are prevented from floating upward by the force of the rainwater discharged from the elbow 547, and the load on the elbow 541 can be reduced.

[0153] (Additional notes) (a) a catchment area for collecting rainwater; A joint disposed below a bottom wall of the water collecting portion; Equipped with The joint is a joint body having an inner wall surface forming a flow passage therein that communicates with the opening of the bottom wall; a plurality of fins disposed within the flow passage around a pipe axis of the fitting body, the fins having upper ends relatively upstream and lower ends relatively downstream; having Drainage structure.

[0154] (b) the fin is detachable from the joint body; A drainage structure as described in (a) above. (c) further comprising a drain pipe connected to the downstream side of the coupling body; The outer diameter of the joint body is the same as the outer diameter of the drain pipe. A drainage structure as described in (a) above. (d) the joint is integral with the water collection portion; A drainage structure as described in (a) above. (e) the flow path an inlet opening located at the top end thereof and having an opening area equal to that of the opening in the bottom wall; a throttle opening located below the inlet opening and communicating with the inlet opening via a contraction inclined surface; The drainage structure according to any one of the above items (a) to (d). (f) when the flow passage is viewed along the tube axis, the fin is disposed at an outer position avoiding overlap with the throttle opening, A drainage structure as described in (e) above. (g) When the inner wall surface is viewed in a cross section including the tube axis, the inclination angle of the inner wall surface with respect to the tube axis is greater than 0° and is equal to or less than 80°. A drainage structure as described in (e) above.

[0155] (h) a catchment area for capturing storm water; A first pipe extending downward from the water collecting portion; a second pipe extending laterally from a lower end of the first pipe; A third pipe having a cleaning port formed at an upper end, a pipe end of the second pipe connected to a side portion, and extending downward; A joint provided at a vertical intermediate position of the third pipe; Equipped with The joint is a coupling body having an inner wall surface forming a flow passage therein that communicates with an opening in the bottom wall of the water collecting portion; and a plurality of fins having an upper end relatively on the upstream side and a lower end relatively on the downstream side and disposed in the flow passage along the periphery of the pipe axis of the coupling body. having Drainage structure.

[0156] (i) the fin is detachable from the joint body; Drainage structure as described in (h) above. (j) the outer diameter of the joint body is the same as the outer diameter of the third pipe; Drainage structure as described in (h) above. (k) the joint body is integral with the third pipe; Drainage structure as described in (h) above. (l) the flow path an inlet opening located at the top end thereof and having an opening area equal to that of the cleaning port; a throttle opening located below the inlet opening and communicating with the inlet opening via a contraction inclined surface; The drainage structure according to any one of the above items (h) to (k). (m) when the flow path is viewed along the tube axis, the fin is disposed at an outer position avoiding overlap with the throttle opening. A drainage structure as described in (l) above. (n) When the inner wall surface is viewed in a cross section including the tube axis, the inclination angle of the inner wall surface with respect to the tube axis is greater than 0° and less than or equal to 80°. A drainage structure as described in (l) above.

[0157] (o) the fin is provided on the inner wall surface such that the upper end of the fin is located within 1000 mm vertically downward from the opening in the bottom wall; The drainage structure according to any one of the above items (a) to (n). (p) the joint body, an inlet connection port provided at an upstream end of the joint body; and an outlet side connection port provided at a downstream end of the joint body, No other connection port is provided between the inlet side connection port and the outlet side connection port in the joint body. The drainage structure according to any one of the above items (a) to (o). [Explanation of symbols]

[0158] 1 to 4: drainage structure, 20: drainage basin (water collection section), 53e: bottom wall, 53e1: circular opening (bottom wall opening), 70, 70A, 70B, 70C, 70D: finned joint (first joint), 80: joint body, 83a: inner wall surface, 83p: throttle opening, 83r: internal flow path (constricted flow inclined surface), 83u: inlet opening, 90: fin, 107: eaves gutter (water collection section), 210: drainage basin (water collection section), 230: first drain pipe (second piping), 240: second drain pipe (third piping), 241: cleaning port, 320: vertical joint (second joint), 330: vertical gutter (first piping)

Claims

1. A catchment section that captures rainwater; A first joint disposed below a bottom wall of the water collecting portion; Equipped with The first joint is a joint body having an inner wall surface forming a flow passage therein that communicates with the opening of the bottom wall; a plurality of fins disposed in the flow passage around a pipe axis of the fitting body, the fins having a relatively upstream upper end and a relatively downstream lower end; having Drainage structure.

2. The fin is provided on the inner wall surface such that the upper end of the fin is located within 1000 mm vertically downward from the opening of the bottom wall. The drainage structure according to claim 1 .

3. The joint body is an inlet connection port provided at an upstream end of the joint body; and an outlet side connection port provided at a downstream end of the joint body, No other connection port is provided between the inlet side connection port and the outlet side connection port in the joint body. The drainage structure according to claim 1 .

4. The flow path is an inlet opening located at the top end thereof and having an opening area equal to that of the opening in the bottom wall; The drainage structure according to any one of claims 1 to 3, further comprising a throttle opening located below the inlet opening and communicating with the inlet opening via a contraction inclined surface.

5. When the flow path is viewed along the tube axis, the fin is disposed at an outer position avoiding overlap with the throttle opening. The drainage structure according to claim 4.

6. a second joint connecting the opening of the water collecting portion and an inlet opening of the first joint; a first pipe connected to the outlet opening of the first joint and extending downward; Further equipped with The fin is separate from the joint body and is connected between the joint body and the first pipe. The drainage structure according to any one of claims 1 to 3.

7. A second pipe connected to the opening of the water collecting portion and extending laterally; a third pipe having a cleaning port formed at an upper end, a pipe end of the second pipe connected to a side portion of the third pipe, and extending downward; Further equipped with The upper end of the first joint is connected to the lower end of the third pipe. The drainage structure according to any one of claims 1 to 3.

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