Siphon Drainage System

Abstract

To provide an elbow for flowing rain water down smoothly.SOLUTION: An elbow 114 is installed at a downstream side of a siphon rain gutter system having an eaves gutter, a cylindrical part penetrating a water collection port formed on a bottom surface of the eaves gutter, and a siphone generation part for generating a siphon phenomenon. The elbow comprises a bent pipe part, and receptacles provided at both ends of the bent pipe part, wherein a radius of curvature of an inner wall surface of an inner peripheral side is greater than 64 mm and smaller than 100 mm in the bent pipe part seen in a cross section in a plane including a tube axis of the bent pipe part.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] Generally, gutters are installed on buildings to catch rainwater that runs off the roof and channel it to the ground. A gutter is made up of multiple components, such as an eaves gutter, a water collector, a downspout, a downspout, a connecting pipe, an elbow joint, and a tee joint (hereinafter, each joint will be simply called an elbow or a tee). In recent years, in order to increase the drainage capacity of gutters, a siphon gutter system has been proposed that fills the downspout with water, generating a water suction effect (the so-called siphon phenomenon) and dramatically increasing the amount of drainage.

[0003] For example, in the siphon type rainwater drainage device disclosed in Patent Document 1, the upper end of a siphon pipe is connected to the bottom of an eaves gutter attached to the eaves. This siphon pipe is installed vertically along the exterior wall material of the house and is 3 to 13 cm long. 2 The opening area is . [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-308399 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the siphon gutter system, elbows are used as joints to connect various gutters and connecting members in the part where rainwater is changed from vertical to horizontal (or from horizontal to vertical). Conventionally standardized elbows include, for example, 90° bent elbows (so-called DL).

[0006] However, the radius of curvature of the inner wall part on the inner circumference side of the 90° bent elbow is 0 mm, and the inner wall part on the inner circumference side is formed at a right angle. Therefore, when a 90° bent elbow is used in a siphon gutter system, there is a problem that the flow rate of rainwater decreases at the inner wall part on the inner circumference side formed at a right angle. In addition, when rainwater is drawn vertically and horizontally, if the downspout or downspout is too short, there is a problem that the flow rate of rainwater decreases. If the flow rate of rainwater decreases, the drainage capacity of the siphon gutter system decreases, and rainwater may overflow at the siphon generation part that generates the siphon phenomenon in the gutter.

[0007] The present invention has been made in consideration of the above circumstances, and provides an elbow and siphon gutter system that allows rainwater to flow smoothly downward. [Means for solving the problem]

[0008] The elbow of the present invention is an elbow that is installed downstream of a siphon gutter system that has an eaves gutter, a tubular portion that penetrates a water collection port formed on the bottom surface of the eaves gutter, and a siphon generating portion for generating a siphon phenomenon, and is characterized in that it has a curved pipe portion and receiving ports provided on both ends of the curved pipe portion, and when viewed in a cross section on a plane including the pipe axis of the curved pipe portion, the radius of curvature of the inner wall surface on the inner circumference side is greater than 64 mm and smaller than 100 mm.

[0009] By using the above-mentioned elbow, rainwater flowing in from one of the receiving ports of the elbow does not stagnate on the inner wall surface on the inner periphery side, and the flow rate of the rainwater does not decrease on the inner wall portion. Therefore, the rainwater flows smoothly toward the other receiving port of the elbow.

[0010] The elbow of the present invention has an opening area of ​​50 cm 2 It may be more than that.

[0011] The above-mentioned elbow has a hollow portion of the curved pipe through which rainwater flows down that has a large opening area, and even when applied to a non-residential building with a large roof area, rainwater flowing in from one receiving port of the elbow does not stagnate on the inner wall surface on the inner circumferential side, and the flow rate of the rainwater does not decrease at the inner wall.

[0012] The siphon gutter system of the present invention is a siphon gutter system having the above-mentioned elbows as a first elbow and a second elbow, wherein one end of the first elbow is connected to the downstream side of the upstream part of the gutter having the siphon generation part, one end of a call gutter that draws rainwater that has flowed down the first elbow horizontally is connected to the other end of the first elbow, one end of the second elbow is connected to the other end of the call gutter, one end of a downspout that draws rainwater that has flowed down the second elbow vertically is connected to the other end of the second elbow, the other end of the downspout is connected to a drainage mechanism having a width larger than the downspout, the length of the call gutter is greater than 0 m and within 2.0 m, and the length of the downspout is 2.0 m or more.

[0013] According to the above-mentioned siphon gutter system, when rainwater flows into the curved pipe section from one end of the first elbow connected to the upstream part of the gutter in a full-water state due to the siphon phenomenon generated in the siphon generating section, the rainwater does not stagnate on the inner peripheral surface side of the inner wall surface, but flows smoothly toward the eaves gutter and the part downstream of the eaves gutter. In addition, by setting the curvature radius of the curved pipe section of the first elbow and the second elbow, and the flow distance of the rainwater drawn horizontally and the flow distance of the rainwater drawn vertically within the above-mentioned ranges, the siphon action from the siphon generating section to the downstream end of the downspout is not easily interrupted and is well maintained. As a result, the rainwater flowing into the first elbow from the siphon generating section does not stagnate on the inner wall surface of the joint or the gutter member, and the flow rate of the rainwater does not decrease on the inner wall part.

[0014] The siphon gutter system of the present invention is a siphon gutter system having the above-mentioned elbows as a first elbow and a second elbow, wherein one end of the first elbow is connected to the downstream side of the upstream part of the gutter having the siphon generation part, one end of a call gutter that draws rainwater flowing down the first elbow horizontally is connected to the other end of the first elbow, one end of the second elbow is connected to the other end of the call gutter, one end of a downspout that draws rainwater flowing down the second elbow vertically is connected to the other end of the second elbow, the other end of the downspout is connected to a drainage mechanism, a junction pipe intersects the downspout at one or more junction positions between one end and the other end of the downspout, the length of the call gutter is greater than 0 m and less than 1.0 m, and the distance between one end of the downspout and the most upstream junction position is 2.0 m or more.

[0015] According to the above-mentioned siphon gutter system, when rainwater flows into the curved pipe section from one end of the first elbow connected to the upstream part of the gutter in a full-water state due to the siphon phenomenon generated in the siphon generating section, the rainwater does not stagnate on the inner peripheral surface side of the inner wall surface, but flows smoothly toward the eaves gutter and the part downstream of the eaves gutter. In addition, by setting the curvature radius of the curved pipe section of the first elbow and the second elbow, the flow distance of the rainwater drawn horizontally, and the flow distance from the upstream end of the downspout to the most upstream joining position within the above-mentioned ranges, the siphon action from the siphon generating section to the downstream end of the downspout is not easily interrupted and is well maintained. As a result, the rainwater flowing into the first elbow from the siphon generating section does not stagnate on the inner wall surface of the joint or the gutter member, and the flow rate of the rainwater does not decrease on the inner wall part.

[0016] In the siphon gutter system of the present invention, the siphon generating section is a cover member arranged above the bottom surface of the eaves gutter so as to cover the opening of a water collection outlet formed on the bottom surface of the eaves gutter when viewed from above, and the first elbow may be connected to the water collection outlet.

[0017] According to the above-mentioned configuration, rainwater collected at the water collection outlet by the eaves gutter is guided between the bottom surface of the eaves gutter and the upper surface of the cover member, and flows into the water collection outlet and the first elbow in a full-water state, thereby ensuring good siphoning. Effect of the Invention

[0018] The elbow and siphon gutter system of the present invention allows rainwater to flow smoothly downward. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional view of a siphon gutter system according to a first embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view showing an example of a siphon drain member that can be installed at the water collection outlet of the siphon gutter system shown in FIG. 1. FIG. [Diagram 3] 2 is another cross-sectional view showing an example of a siphon drain member that can be installed at the water collection outlet of the siphon gutter system shown in FIG. 1. [Figure 4] FIG. 2 is a cross-sectional view of an elbow of the siphon gutter system shown in FIG. [Diagram 5] 2 is a cross-sectional view of the other end of the downspout of the siphon gutter system shown in FIG. 1, a drainage mechanism, and the configuration therebetween. [Figure 6] FIG. 2 is a cross-sectional view of another elbow of the siphon gutter system shown in FIG. [Figure 7] 2 is a cross-sectional view of a modified example of the other end of the downpipe, the drainage mechanism, and the configuration between them of the siphon gutter system shown in FIG. 1. FIG. [Figure 8] 8 is a cross-sectional view of a part of the configuration shown in FIG. 7, taken along the direction D2 and from the downstream side to the upstream side. [Figure 9] FIG. 8 is a plan view of a portion of the configuration shown in FIG. [Figure 10] FIG. 2 is a cross-sectional view showing the flow of rainwater in the siphon gutter system shown in FIG. 1. [Figure 11] FIG. 2 is a cross-sectional view showing the flow of rainwater in the siphon gutter system shown in FIG. 1. [Figure 12] FIG. 2 is a cross-sectional view showing the flow of rainwater in the siphon gutter system shown in FIG. 1. [Figure 13] FIG. 2 is a cross-sectional view showing the flow of rainwater in the siphon gutter system shown in FIG. 1. [Figure 14] FIG. 2 is a cross-sectional view showing the flow of rainwater in the siphon gutter system shown in FIG. 1. [Figure 15] FIG. 4 is a cross-sectional view of a siphon gutter system according to a second embodiment of the present invention. [Figure 16] FIG. 1 is a perspective view of a siphon gutter system according to a first embodiment. [Figure 17] 17 is a graph showing the change in water level in the eaves gutter depending on the measurement position and the length of the call gutter when the amount of drainage into the eaves gutter is changed in five ways in the siphon gutter system of FIG. 16. [Figure 18] FIG. 17 is a diagram showing the results of observing the initial stability and drainage capacity when the siphon generating part is changed among seven types in the siphon gutter system of FIG. 16. [Figure 19] FIG. 11 is a perspective view of a siphon gutter system according to a second embodiment. [Figure 20] This is a graph showing the change in water level in the eaves gutter depending on the amount of water drained to the connecting pipe (branch pipe) and the length of the upstream downpipe when the amount of water drained to the eaves gutter (10A, main pipe) is changed in seven different ways in the siphon gutter system of Figure 19. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the elbow and siphon gutter system of the present invention will be described with reference to the drawings. Note that the drawings used in the following description are schematic.

[0021] First embodiment As shown in Figure 1, a first embodiment of a siphon gutter system 101 to which the present invention is applied comprises an eaves gutter 10 fixed to the eaves edge so as to be approximately horizontal, an elbow (first elbow) 114 connected to the downstream side of the eaves gutter 10, a lower gutter 16 connected to the downstream end of the elbow 114, an elbow (second elbow) 118 connected to the downstream end 16a of the lower gutter 16, and a downspout 20 connected to the downstream end 18b of the elbow 118.

[0022] The eaves gutter 10 is provided under the eaves of a building (not shown). The eaves gutter 10 opens upward and extends in the D1 direction. In a cross-sectional view perpendicular to the D1 direction, the eaves gutter 10 has a bottom 10b and side walls 10s, 10s rising upward from both sides in the width direction of the bottom 10b (D2 direction in FIG. 1). The siphon gutter system 101 is assumed to be used in non-residential buildings having a large roof area, such as factories and train stations. In such an assumption, in order to ensure a sufficient flow rate to drain rainwater flowing in from a large-area roof, the width (length in the D2 direction) of the bottom 10b is preferably at least 100 mm or more, more preferably 120 mm or more, and even more preferably 150 mm or more. The upper limit of the width of the bottom 10b is not particularly limited, but the width of the bottom 10b is preferably 300 mm or less.

[0023] A water collection port 12 penetrating the bottom 10b is formed at a predetermined position in the D1 direction (longitudinal direction) of the bottom 10b. In the D1 direction, the upper surface of the bottom 10b (i.e., the inner surface of the eaves gutter 10) descends slightly toward the water collection port 12. The lower surface of the bottom 10b may be formed approximately horizontally and only the upper surface of the bottom 10b may descend toward the water collection port 12, or the thickness of the bottom 10b may be approximately constant and the bottom 10b itself may descend toward the water collection port 12.

[0024] A siphon generating unit 50 for generating a siphon phenomenon in the siphon gutter system 101 is provided at the water collection port 12. Specific configuration examples of the siphon generating unit 50 include a siphon drain member 51 shown in Fig. 2 and a siphon drain member 52 shown in Fig. 3. The siphon generating unit 50 preferably includes a cover member that covers the opening of the water collection port 12.

[0025] As shown in FIG. 2, the siphon drain member 51 includes a net (cover member) 61 disposed above the water collection port 12, a mounting tube 62 having a drop port 70 and extending downward from the water collection port 12, a plurality of vertical ribs (cover member) 63 that connect the net 61 and the mounting tube 62 in the D3 direction and are arranged at intervals in the circumferential direction at positions that do not overlap the drop port 70 in a top view, and a flange upper portion 64 that expands in diameter radially outward from the connection portion between the net 61 and the mounting tube 62. The net 61 and the vertical ribs 63 are dust guards to prevent dust and the like from flowing into the water collection port 12. The outer diameter of the mounting tube 62 is set to a size that can be fitted into the water collection port 12. A male thread is formed on the outer peripheral surface of the mounting tube 62. The flange upper portion 64 engages with the upper surface of the bottom portion 10b around the water collection port 12 from above.

[0026] The siphon drain member 51 is connected to the socket 30A of the elbow 14 via a connecting member 95. The connecting member 95 includes a flange lower portion 44 that expands radially outward from the upper end, and a rib 46 that protrudes radially inward from the inner wall surface at a position that is a predetermined height lowered from the upper end along the D3 direction. The flange lower portion 44 engages with the lower surface of the bottom portion 10b around the water collection port 12 from below. The rib 46 is provided to temporarily reduce the inner diameter of the connecting member 95. By reducing the inner diameter of the connecting member 95, an effect similar to the Venturi effect is exerted, making it easier for a full-flow state to occur, and the siphon phenomenon occurs well. A female thread that can be screwed into the outer circumferential surface of the mounting tube 62 is formed on the inner wall surface of the connecting member 95 from the upper end of the connecting member 95 to the rib 46.

[0027] The siphon drain member 51 is attached to the water collection port 12 by sandwiching the bottom portion 10b around the water collection port 12 between the flange upper portion 64 and the flange lower portion 44 while screwing the male thread of the mounting tube 62 into the female thread of the connecting member 95. A socket 30A of an elbow 114, which will be described later, is fitted onto the lower portion of the connecting member 95. The lower portion of the connecting member 95 and the socket 30A may be bonded with an adhesive or the like, or may be fused.

[0028] As shown in Fig. 3, the siphon drain member 52 includes a plate-shaped lid 71, a plurality of vertical ribs 73 that form a drop opening 80, are spaced apart along the outer periphery of the lid 71 at positions that do not overlap the drop opening 80 in a top view, and extend downward from the bottom surface of the lid 71 to support the lid 71, a guide portion 78 that hangs down from the bottom surface of the lid 71 and is formed radially along the radial direction in a top view, and a positioning rib 77 that is spaced apart along the outer periphery of the lid 71 and is provided to protrude upward from the upper surface of the lid 71. The lower end of the guide portion 78 is formed so as to gradually approach the lid 71 as it moves outward from the radial center of the lid 71 in a side view, and has a tapered or bell-mouth shape. The lid 71 reduces the amount of air entrained in the elbow 114 and thus the downpipe 20, making it easier for a full-flow state to occur and more effectively generating the siphon phenomenon.

[0029] The siphon drain member 52 is connected to the socket 30A of the elbow 14 via a connecting member 90. The connecting member 90 includes a cylindrical portion 92 that can be fitted into the socket 30A, and a flange 94 that expands in diameter from the upper end of the cylindrical portion 92. The connecting member 90 is engaged with the bottom portion 10b with the cylindrical portion 92 inserted into the water collection port 12 and the bottom surface of the flange 94 placed on the bottom portion 10b around the water collection port 12. The bottom surfaces of the multiple vertical ribs 73 are machined into a shape that conforms to the upper surface of the flange 94. The multiple vertical ribs 73 and the flange 94, and the cylindrical portion 92 and the socket 30A may each be bonded by an adhesive or the like, or may be fused.

[0030] The elbow 114 is a joint installed on the downstream side of the siphon generation unit 50. As shown in Fig. 1, one receiving port (one end) 30A of the elbow 14 is connected to the water collection port 12 on the downstream side (i.e., the side where rainwater collects) of the eaves gutter 10 where the siphon generation unit 50 is provided.

[0031] 4, the elbow 114 includes a curved pipe portion 132 and sockets 30A, 30B provided at both ends of the curved pipe portion 132. The curved pipe portion 132 is bent at approximately 90° in a side view.

[0032] When viewed in a cross section (plan, the paper surface of FIG. 4) including the pipe axis A of the curved pipe section 132, the radius of curvature R1 of the inner wall surface 133 on the inner periphery side of the curved pipe section 132 and the radius of curvature R2 of the outer wall surface 134 are at least greater than 64 mm and smaller than 125 mm. In order to allow the rainwater W flowing in from the receiving port 30A to flow more smoothly without reducing the flow rate of the rainwater W, the radii of curvature R1 and R2 are preferably greater than 64 mm and smaller than 90 mm in terms of storage and transportation, and are preferably greater than 80 mm and smaller than 100 mm in terms of drainage performance.

[0033] An axis J2 passing through the center C1 of the socket 30A and an axis J3 passing through the center C2 of the socket 30B intersect at a predetermined angle θ in a side view. The angle θ is preferably 90° or more and 135° or less, and is set to 91.1°, for example. Setting the angle θ as described above allows the rainwater W to flow smoothly.

[0034] The linear distance between the centers C1, C2 is H, the diameter of the hollow portion of the sockets 30A, 30B is D, and the diameter of the hollow portion of the curved pipe portion 132 is E. The distance H is, for example, 99 mm or more and 263 mm or less, and preferably 130 mm or more and 190 mm or less. The diameter D is, for example, 88.65 mm, preferably 52 mm or more and 155 mm or less, and more preferably 75 mm or more and 110 mm or less. The diameter E is appropriately set, for example, to 77.55 mm, so that the cross-sectional area of ​​the curved pipe portion 132 caused by the diameter E does not exceed the cross-sectional area of ​​the hollow portion of the nominal gutter 16.

[0035] The elbow 114 is part of a siphon gutter system 101 used in non-residential buildings with large roof areas such as factories and train stations. The opening area of ​​the bent pipe section 132 is 50 cm 2 More than 150cm 2 Less than 65cm is preferable 2 Over 125cm 2 Less than 75cm is preferable. 2 More than 100cm 2The following is even more preferable: By setting the distance H and the diameters D and E within the above-mentioned ranges, the above-mentioned radius of curvature of the inner wall surface 133 can be achieved, while ensuring the minimum flow rate required for drainage and the dimensions of the elbow 114, and the siphon gutter system 101 can be fitted snugly.

[0036] The radius of curvature R3 of the inner wall surface 135 on the outer periphery side of the curved pipe portion 132 and the radius of curvature R4 of the outer wall surface 136 are appropriately set according to the radii of curvature R1, R2, the distance H, and the diameters D, E, etc. For example, when the diameter D is 88.65 mm, the diameter E is 77.55 mm, the radius of curvature R2 is 83.7 mm, and the diameter of the outer periphery of the sockets 30A, 30B is 96.25 mm, the radius of curvature R4 can be set to 163.3 mm. The length of the socket 30A along the axis J1 and the length of the socket 30B along the axis J2 are defined as T. The length T is preferably 25 mm or more and 80 mm or less, and more preferably 35 mm or more and 55 mm or less, with 40 mm as an example. By setting the length T to the above-mentioned upper limit value or less, when the elbow 114 is molded by injection molding, the core is easily removed, and the elbow 114 can be manufactured well. Furthermore, by having the length T be equal to or less than the lower limit value described above, it is possible to prevent the lead pipe 16 from coming loose due to high pressure or vibration when a siphon action occurs, or to prevent water from leaking from the gap between the socket 30B and the lead pipe 16. Note that the parameters of the elbow 114 are not limited to the exemplified values, and it is important that they are appropriately set within the preferred ranges as described above.

[0037] Here, the plane passing through the center of curvature Q of the inner wall surfaces 133 and 135 and along the horizontal direction is defined as the reference plane S1. The plane passing through the center of curvature Q and along the vertical direction is defined as the reference plane S1. In a side view, the plane that forms an angle of 45° with each of the planes along the horizontal direction and the vertical direction and passes through the center of curvature Q is defined as the reference plane S3. The position where the reference plane S3 intersects with the inner wall surface 133 is defined as the reference position P1. In a side view, the angle between the virtual line L1 connecting the center of curvature Q and the reference position P1 and the virtual line L2 connecting the center of curvature Q and the position P2 of the upstream end of the inner wall surface 133 is defined as α1. The angle between the virtual line L1 and the virtual line L3 connecting the center of curvature Q and the position P3 of the downstream end of the inner wall surface 133 is defined as α2. The angles α1 and α2 are preferably 10° or more and 30° or less. It is preferable that the angles α1 and α2 are equal.

[0038] The position where the reference plane S3 and the inner wall surface 135 intersect is defined as the reference position P4. In a side view, the angle between a virtual line L4 connecting the center of curvature Q and the reference position P4 and a virtual line L5 connecting the center of curvature Q and a position P5 of the upstream end of the inner wall surface 135 is defined as β1. The angle between the virtual line L1 and a virtual line L6 connecting the center of curvature Q and a position P6 of the downstream end of the inner wall surface 135 is defined as β2. Each of the angles β1 and β2 is preferably 10° or more and 45° or less, with 44.25° as an example. The angles β1 and β2 are preferably equal to each other.

[0039] In cross-sectional view, the angle between the reference plane S3 and the opening surface 141 of the upstream socket 30A about the center of curvature Q is defined as φ1. The angle between the reference plane S3 and the opening surface 142 of the downstream socket 30B about the center of curvature Q is defined as φ2. The angles φ1 and φ2 are preferably 10° or more and 45° or less, respectively.

[0040] By providing the above-mentioned configuration, the elbow 114 realizes sufficient drainage volume and smooth drainage flow, while at the same time keeping the overall dimensions of the joint moderate. Even if an external force is applied to the nominal gutter 16 due to vibrations caused by the siphoning phenomenon or strong winds, the stress applied to the joint between the eaves gutter 10 and the elbow 114 and the elbow 114 itself can be reduced, preventing damage to the eaves gutter 10 and the elbow 114. Specifically, the distance (shortest distance) between the bottom 10b and the central axis of the nominal gutter 16 is preferably less than 140 mm, and more preferably less than 130 mm.

[0041] As shown in FIG. 1, the upstream end 16a of the call pipe 16 is connected to the receiving port 30B of the elbow 114. The call pipe 16 is a member that horizontally draws rainwater W that has flowed down the elbow 114, and is a straight pipe that extends along the direction D2 or that moves slightly away from the direction D2 as it advances downstream. The length F1 from the end 16a to the downstream end 16b of the call pipe 16 is greater than 0 m and less than 2.0 m, preferably greater than 0.6 m and less than 1.5 m, and more preferably greater than 0.6 m and less than 1.0 m. By having the length G1 within the above-mentioned range, rainwater that flows down from the elbow 114 flows smoothly when the water is full.

[0042] A socket 30A of an elbow 118 is connected to a downstream end (other end) 16b of the outlet pipe 16. The elbow 118 has the same configuration as the elbow 114.

[0043] The upstream end 20a of the downspout 20 is connected to the receiving port 30B of the elbow 118. The downspout 20 is a member that vertically draws rainwater W that has flowed down the elbow 118, and is a straight pipe that extends along the D3 direction (vertical direction and the opposite direction). The downstream end 20b of the downspout 20 is connected to the ground G and is connected to a known water collection basin (drainage mechanism) 180 buried in the ground. The water collection basin 180 is connected to a drainage structure such as a sewer pipe 184 via a connecting pipe 182. The water collection basin 180 has a width larger than that of the downspout 20. The length F2 from the end 20a to the end 20b is 2.0 m or more, preferably 3.0 m or more, and more preferably 4.0 m or more. By having the length F2 within the above-mentioned range, the siphon phenomenon in the downspout 20 is generated and maintained well.

[0044] When the length F2 of the downspout 20 is longer, the amount of rainwater W flowing down to the downstream end 20b increases, and the rainwater W flows forcefully into the water collection basin 180. In consideration of this, as shown in Fig. 5, it is preferable that an elbow 141, a straight pipe 142 extending along the D2 direction, an expansion joint 144, a straight pipe 146, and an elbow 120 are connected to the downstream end 20b in this order.

[0045] One socket 30A of an elbow 141 (elbow 140A) is connected to the downstream end 20b of the downspout 20. The elbow 141 is a combination elbow and includes two elbows 140A and 140B. As shown in FIG. 6, the curved pipe portion 32 of each of the elbows 140A and 140B is bent at approximately 45° in side view. That is, the axes J3 and J4 passing through the sockets 30A and 30B, respectively, intersect at an included angle of 45° in side view. As shown in FIG. 5, by combining the two elbows 140A and 140B, the axis J3 passing through the socket 30A of the elbow 140A and the axis J4 passing through the socket 30B of the elbow 140B intersect at 90° in side view, forming an elbow 141 that is bent at 90° as a whole.

[0046] The upstream end of the straight pipe 142 is connected to the other socket 30B of the elbow 141 (elbow 140B). The downstream end of the straight pipe 142 is connected to the upstream socket of the expansion joint 144. The upstream end of the straight pipe 146 is connected to the downstream socket of the expansion joint 144. The diameter of the hollow part of the straight pipe 146 is larger than the diameter of the hollow part of the straight pipe 142. The straight pipe 146 penetrates the water collection basin 180 midway in the longitudinal direction along the D2 direction. The downstream end of the straight pipe 146 is disposed inside the water collection basin 180. The downstream end of the straight pipe 146 is connected to the socket 30A of the elbow 120. The elbow 120 has the same configuration as the elbow 114. The socket 30B of the elbow 120 opens downward.

[0047] In the configuration shown in Fig. 5, rainwater W (omitted in Fig. 5) that flows down the downspout 20 toward the downstream side in the D3 direction flows down while bending toward the downstream side in the D2 direction by the elbow 141, and flows down approximately horizontally toward the downstream side in the D2 direction through the straight pipe 142, the expansion joint 144, and the straight pipe 146. Furthermore, the rainwater W is discharged from the elbow 120 toward the downstream side in the D3 direction, i.e., downward, and is stored in the water collection basin 180. According to the configuration shown in Fig. 5, by providing the elbow 141, the straight pipe 142, the expansion joint 144, and the straight pipe 146, the flow velocity and drainage amount of the rainwater W that flows down the downspout 20 at high speed can be appropriately suppressed. In addition, according to the configuration shown in Figure 5, an elbow 120 is provided at the downstream end, and the receiving port 30B of the elbow 120 opens downward, thereby preventing the rainwater W from colliding with the side wall of the water collection tank 180, and thereby preventing the rainwater W from being splashed upward by the side wall of the water collection tank 180 and spraying onto the ground.

[0048] For example, when the siphon gutter system 101 is installed in an eight-story building, the amount of drainage to the downspout 20 may reach approximately 20 L / sec. In the configuration shown in Fig. 5, even when the diameter of the hollow part of the downspout 20 is 75 mm, the diameter of the hollow part of the straight pipe 146 is 100 mm, the diameter of the hollow part of the connecting pipe 182 is 150 mm, and the length of the connecting pipe 182 in the D2 direction is 8 m, it has been confirmed that the rainwater W discharged from the receiving port 30B of the elbow 120 into the water collection basin 180 does not gush out above the water collection basin 180, and is drained well from the connecting pipe 182.

[0049] Moreover, among the configurations shown in Fig. 5, it is more preferable that the elbow 120 is an elbow 140C as shown in Fig. 7. The elbow 140C has the same configuration as the elbows 140A and 140B. The receiving port 30B of the elbow 140 opens obliquely downward according to the direction of the axis J4 (see Fig. 6). Because the receiving port 30B of the elbow 140 opens obliquely downward, the straight pipe 142, the expansion joint 144, and the straight pipe 146 are prevented from floating upward in the D3 direction due to the force of the rainwater W discharged from the elbow 140C, and the load on the elbow 141 can be reduced.

[0050] 7, the receiving port 30B of the elbow 140C may open obliquely downward as viewed from the D2 direction (i.e., the direction along the axis J3 (see FIG. 6) of the receiving port 30A) as shown in FIG. 8. By opening obliquely downward in this manner, the rainwater W discharged from the receiving port 30B of the elbow 120 into the water collection basin 180 swirls inside the water collection basin 180, and the swirling rainwater W stirs up the dirt and mud accumulated at the bottom of the water collection basin 180, and the dirt and mud are efficiently discharged to the outside of the water collection basin 180 together with the rainwater W through the connecting pipe 182. Note that, due to the same effect, the receiving port 30B of the elbow 120 may also open obliquely downward as viewed from the D2 direction in the configuration shown in FIG. 5.

[0051] In the configuration shown in Fig. 7, as shown in Fig. 9, it is preferable that the elbow 140C (particularly, the receiving port 30B) is disposed radially outward from the center of the water collection tank 180 in a plan view. By disposing the elbow 140C in this manner, a swirling flow is easily generated inside the water collection tank 180 by the rainwater W discharged from the receiving port 30B of the elbow 120 into the water collection tank 180, and the garbage and mud accumulated inside the water collection tank 180 together with the rainwater W are efficiently discharged to the outside of the water collection tank 180 through the connecting pipe 182. From the same effect, in the configuration shown in Fig. 5, when the receiving port 30B of the elbow 120 opens obliquely downward when viewed from the D2 direction, it is preferable that the elbow 120 (particularly, the receiving port 30B) is disposed radially outward from the center of the water collection tank 180.

[0052] The material of each component of the siphon gutter system 101, including the elbows 114, 118, is, for example, polyvinyl chloride, and rigid polyvinyl chloride is particularly preferred.

[0053] According to the elbows 14, 18 and siphon gutter system 101 of the first embodiment described above, the radius of curvature of the inner wall surface 133 and the outer wall surface 134 is greater than 64 mm and less than 100 mm. This allows the rainwater W that flows from the water collection port 12 into the receiving ports 30A of the elbows 114, 118 to flow smoothly toward the receiving ports 30B without being stagnated by the inner wall surface 133.

[0054] Furthermore, in the siphon gutter system 101 of the first embodiment, by appropriately setting the angles α1, α2, β1, β2, φ1, and φ2 within the aforementioned ranges, the flow direction of the rainwater W from the siphon generating part 50 is changed from direction D3 to direction D2 at approximately the same rate with respect to the imaginary line L1, thereby making it possible to increase the symmetry of the flow distribution in a cross section perpendicular to the pipe axis A and reliably suppress a decrease in the flow speed of the rainwater W flowing down. Also, the size of the elbows 114, 118 can be appropriately suppressed, allowing the siphon gutter system 1 to be fitted snugly.

[0055] In the siphon gutter system 101 of the first embodiment, the receiving port 30A of the elbow 114 is connected to the water collection port 12, the length of the nominal gutter 16 is greater than 0 m and is within 2.0 m, and the length of the downpipe 20 is 2.0 m or more. With this configuration, the rainwater W collected in the water collection port 12 by the eaves gutter 10 can be guided to the drop outlets 70, 80 from between the bottom 10b and the net 61 or the lid 71 and between the vertical ribs 63, 73, and can flow into the water collection port 12 and the elbow 114 in a full water state. When the water level of the rainwater W in the eaves gutter 10 changes from a state in which the water level of the rainwater W in the eaves gutter 10 is lower than the lid 71 of the siphon generating unit 50 (hereinafter referred to as a natural flow state, see FIG. 10) to a state in which the water level of the rainwater W in the eaves gutter 10 is equal to or higher than the lid 71 (hereinafter referred to as a siphon generating state), the rainwater W from the siphon generating unit 50 flows directly into the elbow 114. In the initial siphoning state where the water level of the rainwater W in the eaves gutter 10 is almost the same as that of the lid 71, as shown in Fig. 11, the siphoning phenomenon occurs in the siphoning section 50, and the elbow 114 becomes full downstream of the water collection port 12, so that no air remains at the top of the elbow 114. After this, as shown in Fig. 12, when the amount of drainage from the siphoning section 50 reaches a maximum (i.e., the water level of the rainwater W in the eaves gutter 10 reaches near the highest water level allowed by the eaves gutter 10), the full-water rainwater W causes self-siphoning inside the elbows 114, 118. In addition, the tensile force of the rainwater W on the downstream side pulls the rainwater W on the upstream side downstream, and the rainwater W flows down the inside of the call gutter 16, elbow 118, and downspout 20 in a full-water state, as shown in Fig. 12.

[0056] In the siphon gutter system 101 of the first embodiment, the siphon generating section 50 and the elbow 114 are close to each other, so even if the siphon generating state shown in Fig. 12 changes to the gravity flow state shown in Fig. 13, the siphon action is not interrupted and is maintained because the entrained portion of the air that falls from the outer periphery of the siphon generating section 50 toward the center is shallow. Therefore, even if there is a transition between the gravity flow state shown in Fig. 13 and the siphon generating state shown in Fig. 14, the siphon action at the elbow 114 can be maintained well without interruption. Therefore, the elbows 114, 118 and the siphon gutter system 101 of the first embodiment allow the rainwater W to flow down smoothly.

[0057] The siphon gutter system 101 of the first embodiment includes two elbows 114, 118 between the eaves gutter 10 and the downpipe 20, and one nominal gutter 16 between the elbows 114, 118. However, the siphon gutter system 101 is not limited to a gutter system having such a configuration, and may include at least two elbows and at least one or more nominal gutter 16 between the two or more elbows. The siphon gutter system 101 may include three or more elbows between the eaves gutter 10 and the downpipe 20, and two or more nominal gutter 16 connected by the three or more elbows.

[0058] Second Embodiment Next, a siphon gutter system according to a second embodiment of the present invention will be described. Among the components of the siphon gutter system 102 shown in Fig. 15, the same components as those of the siphon gutter system 101 are given the same reference numerals and their description will be omitted.

[0059] As shown in Fig. 15, the siphon gutter system 102 of the second embodiment includes, in addition to the configuration of the siphon gutter system 101, a downpipe 21 and a junction pipe 28 connected to the downstream side of the downpipe 20, and a tee pipe 140 connecting the downpipes 20, 21 and the junction pipe 28. In the siphon gutter system 102, two downpipes 20, 21 are provided as downpipes downstream of the elbow 118. That is, if the downpipes 20, 21 are combined into one downpipe, in the siphon gutter system 102, the junction pipe 28 intersects the downpipes 20, 21 at a junction position X1 between an end (one end) 20a of the uppipe 20 on the upstream side and an end (the other end) 21b on the downstream side of the downpipe 21 on the downstream side. A distance F3 from the end 20a to the joining position X1 is 2.0 m or more.

[0060] The tee 140 is a joint installed to allow the rainwater W that has flowed down the downspout 20 toward the lower side in the D3 direction and the rainwater W that has flowed down the junction pipe 28 to flow down to the downspout 21. The tee 140 includes a main pipe 145 extending linearly along the D3 direction, sockets 130A and 130B provided at both ends of the main pipe 145, a branch pipe 143 that branches off from the middle of the main pipe 145 in the D3 direction and protrudes along the D2 direction, and a socket 130C provided at the tip of the branch pipe 143. The downstream end 20b of the downspout 20 is connected to the socket 130A. The upstream end 21a of the downspout 21 is connected to the socket 130B. The downstream end 21b of the downspout 21 is connected to the ground G and to a known water collection sump 180 buried in the ground.

[0061] Junction pipe 28 is a member that horizontally draws rainwater W that has flowed down the upstream part of the gutter (not shown), and extends along the direction D2. Downstream end 28b of junction pipe 28 is connected to receiver 130C. Although not shown, the configuration upstream of junction pipe 28 is not particularly limited. For example, the upstream side of junction pipe 28 may be provided with a configuration similar to eaves gutter 10, elbow 114, call gutter 16, elbow 118, and downspout 20.

[0062] The elbows 114, 118 of the second embodiment have the same configuration as the elbows 114, 118 of the first embodiment, and therefore the same action and effect can be obtained. In addition, in the siphon gutter system 102 of the second embodiment, the receiving port 30A of the elbow 114 is connected to the water collection port 12, the length of the nominal gutter 16 is greater than 0 m and is within 1.0 m, and the distance from the upstream end 20a of the downpipe 20 to the joining position X1 (i.e., the length of the downpipe 20) is 2.0 m or more. With this configuration, even if there is a transition between the natural flow state shown in FIG. 13 and the siphon generation state shown in FIG. 14, the siphon action at the elbow 114 can be maintained well without interruption (FIGS. 13 and 14). Therefore, the elbows 114, 118 and the siphon gutter system 102 of the second embodiment can smoothly flow down the rainwater.

[0063] As in the second embodiment, the siphon gutter system 101 of the second embodiment also has a lower pipe 16 with elbows 110 connected to both ends between the eaves gutter 10 and the downpipe 20, with the upstream elbow 110 connected to the bottom 10b of the eaves gutter 10 and the downstream elbow 110 connected to the downpipe 20, but is not limited to this and it is sufficient to have at least two elbows 110 and at least one or more lower pipes 16 between the two or more elbows 110, and it may also be possible to have three or more elbows 110 between the eaves gutter 10 and the downpipe 20 and two or more lower pipes 16 between the three or more elbows 110.

[0064] In the above-described siphon gutter system 102, there is only one junction position X1, but multiple junction positions X may be provided. When multiple junction positions X are provided, the distance is from the upstream end 20a of the downpipe 20 to the most upstream junction position X1 among the multiple junction positions X. In the siphon gutter system of the present invention, such as the siphon gutter system 101 of the first embodiment and the siphon gutter system 102 of the second embodiment, the distance from the upstream end 20a of the downpipe 20 to the position where some change occurs in the downstream direction of the rainwater W (i.e., the length of the downpipe 20) is 2.0 m or more. Examples of cases in which the flow direction of rainwater W is changed include, in the first embodiment, "being discharged into a catchment basin 180 having a width greater than the downspout 20," in the second embodiment, "merging with the junction pipe 28," and "connecting an elbow having a configuration similar to elbow 114 or elbow 141 to the downstream end 20b of the downspout 20 (see Figures 5 and 7)," among others.

[0065] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims.

[0066] For example, the upstream part of the gutter in the present invention is not limited to the eaves gutter 10, but may be any gutter member or water collector as long as it can form a water collection port and can be provided with a siphon generation part. For example, the upstream part of the gutter may include a drain formed in the roof slab of a concrete building, and an elbow 114, a nominal gutter 16, an elbow 118, and a downspout 20 buried so as to penetrate the roof slab of the building. In such a siphon drainage system, the siphon generation part 50 may be provided on the bottom surface of the drain and above the elbow 114.

[0067] The configuration of the siphon generating unit 50 is not limited to the above-mentioned siphon drain members 51 and 52, and may be any configuration that allows rainwater to flow into the water collection port 12 in a full-water state, such as a member that generates a siphon using a water storage container that stores water, as described in JP 2012-132192 A. The elbow of the present invention may be installed downstream of such a member. If rainwater can flow into the water collection port 12 in a full-water state without the need for any member, the water collection port 12 can function as a siphon generating unit.

[0068] In addition, the siphon gutter system of the present invention does not necessarily have to have elbows 114, 118 between the eaves gutter 10 and the nominal gutter 16, and between the nominal gutter 16 and the downspout 20, and other elbows or right-angle joints may be provided as long as they do not reduce the flow rate of rainwater. EXAMPLES

[0069] Next, examples of the elbow according to the present invention will be described. Note that the configuration and the effects of the elbow according to the present invention are not limited to the following examples.

[0070] Example 1 As shown in FIG. 16, an experimental model of the siphon gutter system 101 of the first embodiment was prepared, and a predetermined amount of water was allowed to flow into the eaves gutter 10 to observe the siphon generation and to measure the water level in the eaves gutter 10. The eaves gutter 10 has a length of 15 m along the D1 direction. The siphon generation section 50 was provided near one end of the eaves gutter 10 in the D1 direction (the end on the near side in the D1 direction in FIG. 16). The critical water level of the eaves gutter 10 was set to 150 mm. The water level of the eaves gutter 10 was measured using a water level gauge at a position a distance Y away from the siphon generation section 50 along the D1 direction, and the distance Y was changed to three values: 0.4 m, 5 m, and 14 m. The radius of curvature of the inner wall surface 133 in the cross-sectional view of the elbows 114 and 118 was set to 83.7 mm, and the opening area of ​​the curved pipe section 132 was set to 5410 mm. 2The materials of the eaves gutter 10, siphon generating part 50, and elbow 114 of the siphon gutter system 1 were hard polyvinyl chloride. The amount of drainage to the eaves gutter 10 was changed to five levels: 4 L / sec, 8 L / sec, 12 L / sec, 16 L / sec, and 20 L / sec. The length F1 of the nominal gutter 16 was changed to four levels: 0.6 m shown by the solid line in Fig. 16, 1.0 m, 1.5 m, and 2.0 m. The length F2 of the downpipe 20 was fixed at 2.4 m. The water discharged from the downpipe 20 was scooped up in a container.

[0071] FIG. 17 is a graph showing the change in the water level of the eaves gutter 10 depending on the distance Y and the length F1 when the amount of drainage to the eaves gutter 10 is changed in five different ways. As shown in FIG. 17, even if the length of the eaves gutter 10 is secured to 15 m, it becomes difficult to draw water downstream when the nominal gutter 16 is longer. Specifically, in the cases where the nominal gutter 16 length F1 = 0.6 m and 1.0 m, the water level in the eaves gutter 10 rises as the amount of drainage to the eaves gutter 10 and the distance Y increase, but it remains within the range of less than 150 mm, which is the limit water level of the eaves gutter 10. The drainage performance slightly deteriorates when the length F1 exceeds 1 m. In the case of the length F1 = 1.5 m, if the amount of drainage to the eaves gutter 10 is up to 16 L / sec, the water level in the eaves gutter 10 remains within the range of less than 150 mm, but when it reaches 20 L / sec, the water overflows from the eaves gutter 10 and becomes impossible to measure. When the length F1 is 2.0 m, if the drainage rate into the eaves gutter 10 is up to 12 L / sec, the water level in the eaves gutter 10 will be within a range of less than 150 mm, but when the drainage rate into the eaves gutter 10 reaches 16 L / sec, the water overflows from the eaves gutter 10 and measurement becomes impossible.

[0072] That is, from the results of Example 1, it was confirmed that the length F1 to the downstream end 16b of the call downpipe 16 is at least greater than 0 m and not greater than 2.0 m, preferably greater than 0.6 m and not greater than 1.5 m, and more preferably greater than 0.6 m and not greater than 1.0 m.

[0073] FIG. 18 shows the results of observing the initial stability and drainage capacity when the siphon generating part 50 is changed to seven types from No. 1 to No. 7. In this observation, the distance Y was 1.0 m and the length F1 was 3.0 m. Regarding the evaluation of the initial stability, if the water level at the time of siphon action occurrence is 90 mm or less when the drainage amount to the eaves gutter 10 is 12 L / sec, it is evaluated as "Good", if it is more than 90 mm and less than 120 mm, it is evaluated as "Good", if it is more than 120 mm and less than 120 mm, it is evaluated as "Good", if it is more than 120 mm and less than 150 mm, it is evaluated as "Good", if it is more than 150 mm and less than 150 mm, it is evaluated as "Good", if it is more than 150 mm and more than 150 mm, it is evaluated as "Good". As shown in FIG. 18, the configuration of the seven types of siphon generating parts varies from a simple "funnel-shaped" configuration to a relatively complex "lid mesh", but for example, the initial stability of the "support + vortex suppression rib" was evaluated as "Good". On the other hand, with regard to the drainage capacity, for example, the "support + vortex suppression rib" was rated "△", but the other six types of siphon generation unit 50 configurations were rated "◯". Thus, it was confirmed that with the siphon gutter system 101, good drainage characteristics can be obtained even when using a relatively simple configuration or any type of siphon generation unit 50 configuration.

[0074] Example 2 As shown in Fig. 19, an experimental model of the siphon gutter system 102 of the second embodiment was prepared, and a predetermined amount of water was allowed to flow into the eaves gutters 10A and 10B to observe the state of siphoning and to measure the water level in the eaves gutter 10. To the upstream side of the junction pipe 28, from the nearest side, an elbow 119, a downspout 20B, an elbow 118B, a nominal gutter 16B, an elbow 114B, a connecting member 90, a siphon generation unit 52B, and an eaves gutter 10B were connected. The elbow 119 has the same configuration as the elbow 114 described in the first embodiment.

[0075] The water level of the eaves gutters 10A and 10B was measured at a position 0.4 m away from the siphon generation part 50 along the direction D1 using the above-mentioned water level measuring instrument (omitted in FIG. 19). The radius of curvature of the inner wall surface 133 in the cross-sectional view of the elbows 114A, 114B, 118A, 118B, and 119 was 83.7 mm, and the opening area of ​​the curved pipe part 132 was 5410 mm. 2 The drainage amount to the eaves gutter 10A was changed to seven types, 2L / sec, 4L / sec, 6L / sec, 8L / sec, 10L / sec, 12L / sec, and 14L / sec. The drainage amount to the eaves gutter 10B (i.e., the drainage amount to the junction pipe 28) was changed to three types, 4L / sec, 2L / sec, and 0L / sec (i.e., a state in which no water flows in from the junction pipe 28). The length F1 of the nominal gutters 16A and 16B was fixed to 0.6m. The distance F3 from the upstream end of the downspout 20 to the junction position X1 was changed to three types, 0m (i.e., a state in which a short pipe is fitted into the downstream receptacle of the elbow 118A and the upstream receptacle of the tee 140 is in contact with the downstream receptacle of the elbow 118A), 3.0m, and 15m, by changing the position of the downspout in the longitudinal direction. The water discharged from the downspout 21 was collected in a container.

[0076] FIG. 20 is a graph showing the change in the water level of the eaves gutter 10A depending on the amount of water discharged to the junction pipe 28 (branch pipe) and the distance F3 when the amount of water discharged to the eaves gutter 10A (main pipe) is changed to seven different levels. As shown in FIG. 20, if the amount of water flowing into the junction pipe 28 is small, air gets into the water in the hollow parts of various joints and gutter members, and the siphon effect on the main pipe side does not occur. Specifically, the water level in the eaves gutter 10A increases as the amount of water discharged to the junction pipe 28 decreases or the distance Y increases. When the amount of water discharged to the junction pipe 28 is 4 L / sec, the water level in the eaves gutter 10A remains within a range of less than 150 mm regardless of whether the distance F3 is 0 m, 3.0 m, or 15 m, or the amount of water discharged to the eaves gutter 10A is any of the seven different levels. On the other hand, when the amount of drainage to the junction pipe 28 was reduced to 2 L / sec, the water level in the eaves gutter 10A was within a range of less than 150 mm if the amount of drainage to the eaves gutter 10A was 12 L / sec or less, but when the amount of drainage to the eaves gutter 10A was 14 L / sec, the water overflowed from the eaves gutter 10A and measurement was impossible. Also, when the amount of drainage to the junction pipe 28 was reduced to 0 L / sec, the water level in the eaves gutter 10A was within a range of less than 150 mm if the amount of drainage to the eaves gutter 10A was 8 L / sec or less, but when the amount of drainage to the eaves gutter 10A was 10 L / sec, the water overflowed from the eaves gutter 10A and measurement was impossible.

[0077] That is, it was confirmed from the results of Example 2 that the distance F3 is preferably 2.0 m or more. It was also confirmed that the amount of drainage to the connecting pipe 28 is preferably at least 4 L / sec. [Explanation of symbols]

[0078] 101,102...Siphon gutter system 114,118…Elbow 30A, 30B…receptacle 32...Bent pipe 133…Inner wall surface 134…Inner wall surface 50…Siphon generating section

Claims

1. A siphon drainage system provided with a siphon generating unit, A first elbow having one end connected to the downstream side of the upstream portion having the siphon generating portion; a second elbow having one end connected to the upstream side of the first pipe; a second pipe provided between the first elbow and the second elbow; a water collection basin connected to the downstream side of the first pipe, the downstream end of the first pipe being disposed therein and opening therein; The water collection tank is provided with an opening surface at a downstream end of the first pipe that opens downward within the water collection tank and discharges the rainwater that has flowed down the second elbow into the water collection tank, and a connecting pipe that drains the rainwater from the water collection tank, The opening surface is located above the connecting pipe, the first elbow and the second elbow each include a curved pipe portion having an inner wall surface on an inner periphery side thereof, the inner wall surface having a radius of curvature greater than 64 mm and smaller than 125 mm when viewed in a cross section on a plane including a pipe axis; Furthermore, the first elbow and the second elbow each have a bent pipe portion having an opening area of ​​50 cm 2 or more. Siphon drainage system.

2. a downstream end of the first pipe includes a third elbow, an expansion joint, and a fourth elbow, in this order; the fourth elbow is disposed in the water collection basin; The fourth elbow has an opening surface that opens downward or obliquely downward in the water collection basin.

2. The siphon drainage system of claim 1.

3. The first pipe is provided with a joint that allows the rainwater that has flowed down the junction pipe to flow down to the first pipe.

2. The siphon drainage system of claim 1.

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